Bump version to v0.1.13 (#771)

This also bumps the following sub crate versions:

* tokio-current-thread (0.1.4)
* tokio-reactor (0.1.7)
* tokio-signal (0.2.7)
* tokio-threadpool (0.1.9)
* tokio-timer (0.2.8)
* tokio-udp (0.1.3)
* tokio-uds (0.2.4)

.appveyor.yml

@@ -1,3 +1,4 @@
+image: Visual Studio 2017
 environment:
   matrix:
   - TARGET: x86_64-pc-windows-msvc
@@ -9,6 +10,7 @@ install:
   - appveyor-retry appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe
   - rustup-init.exe -y --default-host %TARGET%
   - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
+  - set RUST_BACKTRACE=1
 
   - rustc -V
   - cargo -V
@@ -16,4 +18,4 @@ install:
 build: false
 
 test_script:
-  - cargo test --all --target %TARGET%
+  - cargo test --all --no-fail-fast --target %TARGET%

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,51 @@
+<!--
+Thank you for reporting an issue.
+
+Please fill in as much of the template below as you're able.
+-->
+
+## Version
+
+<!--
+List the versions of all `tokio` crates you are using. The easiest way to get
+this information is using `cargo-tree`.
+
+`cargo install cargo-tree`
+(see install here: https://github.com/sfackler/cargo-tree)
+
+Then:
+
+`cargo tree | grep tokio`
+-->
+
+## Platform
+
+<!---
+Output of `uname -a` (UNIX), or version and 32 or 64-bit (Windows)
+-->
+
+## Subcrates
+
+<!--
+If known, please specify the affected Tokio sub crates. Otherwise, delete this
+section.
+-->
+
+## Description
+
+<!--
+
+Enter your issue details below this comment.
+
+One way to structure the description:
+
+<short summary of the bug>
+
+I tried this code:
+
+<code sample that causes the bug>
+
+I expected to see this happen: <explanation>
+
+Instead, this happened: <explanation>
+-->

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,23 @@
+<!--
+Thank you for your Pull Request. Please provide a description above and review
+the requirements below.
+
+Bug fixes and new features should include tests.
+
+Contributors guide: https://github.com/tokio-rs/tokio/blob/master/CONTRIBUTING.md
+-->
+
+## Motivation
+
+<!--
+Explain the context and why you're making that change. What is the problem
+you're trying to solve? In some cases there is not a problem and this can be
+thought of as being the motivation for your change.
+-->
+
+## Solution
+
+<!--
+Summarize the solution and provide any necessary context needed to understand
+the code change.
+-->

.travis.yml

@@ -15,19 +15,36 @@ matrix:
   # This represents the minimum Rust version supported by Tokio. Updating this
   # should be done in a dedicated PR and cannot be greater than two 0.x
   # releases prior to the current stable.
-  - rust: 1.25.0
+  - rust: 1.26.0
   - rust: stable
   - rust: beta
   - rust: nightly
+    env: ALLOW_FAILURES=true
   - os: osx
   - env: TARGET=x86_64-unknown-freebsd
   - env: TARGET=i686-unknown-freebsd
   - env: TARGET=i686-unknown-linux-gnu
 
+  # Test the async / await preview. We don't want to block PRs on this failing
+  # though.
+  - rust: nightly
+    env: ALLOW_FAILURES=true
+    script: |
+      cd tokio-async-await
+      cargo check --all
+
+  # This runs TSAN against nightly and allows failures to propagate up.
+  - rust: nightly-2018-11-18
+    env: TSAN=yes
+
+  allow_failures:
+    - rust: nightly
+      env: ALLOW_FAILURES=true
+
 script:
   - |
     set -e
-    if [[ "$TRAVIS_RUST_VERSION" == nightly ]]
+    if [[ "$TRAVIS_RUST_VERSION" == nightly && "$TSAN" == yes ]]
     then
         # Make sure the benchmarks compile
         cargo build --benches --all
@@ -64,7 +81,7 @@ script:
         cargo check --all --exclude tokio-tls --target $TARGET
         cargo check --tests --all --exclude tokio-tls --target $TARGET
     else
-        cargo test --all
+        cargo test --all --no-fail-fast
         # Disable these tests for now as they are buggy
         #
         # cargo test --features unstable-futures
@@ -85,7 +102,7 @@ deploy:
     branch: master
     repo: tokio-rs/tokio
     rust: stable
-    condition: $TRAVIS_OS_NAME = linux
+    condition: $TRAVIS_OS_NAME = "linux" && $TARGET = ""
 
 env:
   global:

CHANGELOG.md

@@ -1,6 +1,43 @@
 This changelog only applies to the `tokio` crate proper. Each sub crate
 maintains its own changelog tracking changes made in each respective sub crate.
 
+# 0.1.13 (November 21, 2018)
+
+* Fix `Runtime::reactor()` when no tasks are spawned (#721).
+* `runtime::Builder` no longer uses deprecated methods (#749).
+* Provide `after_start` and `before_stop` configuration settings for
+  `Runtime` (#756).
+* Implement throttle stream combinator (#736).
+
+# 0.1.12 (October 23, 2018)
+
+* runtime: expose `keep_alive` on runtime builder (#676).
+* runtime: create a reactor per worker thread (#660).
+* codec: fix panic in `LengthDelimitedCodec` (#682).
+* io: re-export `tokio_io::io::read` function (#689).
+* runtime: check for executor re-entry in more places (#708).
+
+# 0.1.11 (September 28, 2018)
+
+* Fix `tokio-async-await` dependency (#675).
+
+# 0.1.10 (September 27, 2018)
+
+* Fix minimal versions
+
+# 0.1.9 (September 27, 2018)
+
+* Experimental async/await improvements (#661).
+* Re-export `TaskExecutor` from `tokio-current-thread` (#652).
+* Improve `Runtime` builder API (#645).
+* `tokio::run` panics when called from the context of an executor
+  (#646).
+* Introduce `StreamExt` with a `timeout` helper (#573).
+* Move `length_delimited` into `tokio` (#575).
+* Re-organize `tokio::net` module (#548).
+* Re-export `tokio-current-thread::spawn` in current_thread runtime
+  (#579).
+
 # 0.1.8 (August 23, 2018)
 
 * Extract tokio::executor::current_thread to a sub crate (#370)

CONTRIBUTING.md

@@ -0,0 +1,387 @@
+# Contributing to Tokio
+
+:balloon: Thanks for your help improving the project! We are so happy to have
+you!
+
+There are opportunities to contribute to Tokio at any level. It doesn't matter if
+you are just getting started with Rust or are the most weathered expert, we can
+use your help.
+
+**No contribution is too small and all contributions are valued.**
+
+This guide will help you get started. **Do not let this guide intimidate you**.
+It should be considered a map to help you navigate the process.
+
+You may also get help with contributing in the [dev channel][dev], please join
+us!
+
+[dev]: https://gitter.im/tokio-rs/dev
+
+## Conduct
+
+The Tokio project adheres to the [Rust Code of Conduct][coc]. This describes
+the _minimum_ behavior expected from all contributors.
+
+[coc]: https://github.com/rust-lang/rust/blob/master/CODE_OF_CONDUCT.md
+
+## Contributing in Issues
+
+For any issue, there are fundamentally three ways an individual can contribute:
+
+1. By opening the issue for discussion: For instance, if you believe that you
+   have uncovered a bug in Tokio, creating a new issue in the tokio-rs/tokio
+   issue tracker is the way to report it.
+
+2. By helping to triage the issue: This can be done by providing
+   supporting details (a test case that demonstrates a bug), providing
+   suggestions on how to address the issue, or ensuring that the issue is tagged
+   correctly.
+
+3. By helping to resolve the issue: Typically this is done either in the form of
+   demonstrating that the issue reported is not a problem after all, or more
+   often, by opening a Pull Request that changes some bit of something in
+   Tokio in a concrete and reviewable manner.
+
+**Anybody can participate in any stage of contribution**. We urge you to
+participate in the discussion around bugs and participate in reviewing PRs.
+
+### Asking for General Help
+
+If you have reviewed existing documentation and still have questions or are
+having problems, you can open an issue asking for help.
+
+In exchange for receiving help, we ask that you contribute back a documentation
+PR that helps others avoid the problems that you encountered.
+
+### Submitting a Bug Report
+
+When opening a new issue in the Tokio issue tracker, users will be presented
+with a [basic template][template] that should be filled in. If you believe that you have
+uncovered a bug, please fill out this form, following the template to the best
+of your ability. Do not worry if you cannot answer every detail, just fill in
+what you can.
+
+The two most important pieces of information we need in order to properly
+evaluate the report is a description of the behavior you are seeing and a simple
+test case we can use to recreate the problem on our own. If we cannot recreate
+the issue, it becomes impossible for us to fix.
+
+In order to rule out the possibility of bugs introduced by userland code, test
+cases should be limited, as much as possible, to using only Tokio APIs.
+
+See [How to create a Minimal, Complete, and Verifiable example][mcve].
+
+[mcve]: https://stackoverflow.com/help/mcve
+[template]: .github/PULL_REQUEST_TEMPLATE.md
+
+### Triaging a Bug Report
+
+Once an issue has been opened, it is not uncommon for there to be discussion
+around it. Some contributors may have differing opinions about the issue,
+including whether the behavior being seen is a bug or a feature. This discussion
+is part of the process and should be kept focused, helpful, and professional.
+
+Short, clipped responses—that provide neither additional context nor supporting
+detail—are not helpful or professional. To many, such responses are simply
+annoying and unfriendly.
+
+Contributors are encouraged to help one another make forward progress as much as
+possible, empowering one another to solve issues collaboratively. If you choose
+to comment on an issue that you feel either is not a problem that needs to be
+fixed, or if you encounter information in an issue that you feel is incorrect,
+explain why you feel that way with additional supporting context, and be willing
+to be convinced that you may be wrong. By doing so, we can often reach the
+correct outcome much faster.
+
+### Resolving a Bug Report
+
+In the majority of cases, issues are resolved by opening a Pull Request. The
+process for opening and reviewing a Pull Request is similar to that of opening
+and triaging issues, but carries with it a necessary review and approval
+workflow that ensures that the proposed changes meet the minimal quality and
+functional guidelines of the Tokio project.
+
+## Pull Requests
+
+Pull Requests are the way concrete changes are made to the code, documentation,
+and dependencies in the Tokio repository.
+
+Even tiny pull requests (e.g., one character pull request fixing a typo in API
+documentation) are greatly appreciated. Before making a large change, it is
+usually a good idea to first open an issue describing the change to solicit
+feedback and guidance. This will increase the likelihood of the PR getting
+merged.
+
+### Tests
+
+If the change being proposed alters code (as opposed to only documentation for
+example), it is either adding new functionality to Tokio or it is fixing
+existing, broken functionality. In both of these cases, the pull request should
+include one or more tests to ensure that Tokio does not regress in the future.
+There are two ways to write tests: integration tests and documentation tests
+(Tokio avoids unit tests as much as possible).
+
+#### Integration tests
+
+Integration tests go in the same crate as the code they are testing. Each sub
+crate should have a `dev-dependency` on `tokio` itself. This makes all Tokio
+utilities available to use in tests, no matter the crate being tested.
+
+The best strategy for writing a new integration test is to look at existing
+integration tests in the crate and follow the style.
+
+#### Documentation tests
+
+Ideally, every API has at least one [documentation test] that demonstrates how to
+use the API. Documentation tests are run with `cargo test --doc`. This ensures
+that the example is correct and provides additional test coverage.
+
+The trick to documentation tests is striking a balance between being succinct
+for a reader to understand and actually testing the API.
+
+Same as with integration tests, when writing a documentation test, the full
+`tokio` crate is available. This is especially useful for getting access to the
+runtime to run the example.
+
+The documentation tests will be visible from both the crate specific
+documentation **and** the `tokio` facade documentation via the re-export. The
+example should be written from the point of view of a user that is using the
+`tokio` crate. As such, the example should use the API via the facade and not by
+directly referencing the crate.
+
+The type level example for `tokio_timer::Timeout` provides a good example of a
+documentation test:
+
+```
+/// # extern crate futures;
+/// # extern crate tokio;
+/// // import the `timeout` function, usually this is done
+/// // with `use tokio::prelude::*`
+/// use tokio::prelude::FutureExt;
+/// use futures::Stream;
+/// use futures::sync::mpsc;
+/// use std::time::Duration;
+///
+/// # fn main() {
+/// let (tx, rx) = mpsc::unbounded();
+/// # tx.unbounded_send(()).unwrap();
+/// # drop(tx);
+///
+/// let process = rx.for_each(|item| {
+///     // do something with `item`
+/// # drop(item);
+/// # Ok(())
+/// });
+///
+/// # tokio::runtime::current_thread::block_on_all(
+/// // Wrap the future with a `Timeout` set to expire in 10 milliseconds.
+/// process.timeout(Duration::from_millis(10))
+/// # ).unwrap();
+/// # }
+```
+
+Given that this is a *type* level documentation test and the primary way users
+of `tokio` will create an instance of `Timeout` is by using
+`FutureExt::timeout`, this is how the documentation test is structured.
+
+Lines that start with `/// #` are removed when the documentation is generated.
+They are only there to get the test to run. The `block_on_all` function is the
+easiest way to execute a future from a test.
+
+If this were a documentation test for the `Timeout::new` function, then the
+example would explicitly use `Timeout::new`. For example:
+
+```
+/// # extern crate futures;
+/// # extern crate tokio;
+/// use tokio::timer::Timeout;
+/// use futures::Future;
+/// use futures::sync::oneshot;
+/// use std::time::Duration;
+///
+/// # fn main() {
+/// let (tx, rx) = oneshot::channel();
+/// # tx.send(()).unwrap();
+///
+/// # tokio::runtime::current_thread::block_on_all(
+/// // Wrap the future with a `Timeout` set to expire in 10 milliseconds.
+/// Timeout::new(rx, Duration::from_millis(10))
+/// # ).unwrap();
+/// # }
+```
+
+### Commits
+
+It is a recommended best practice to keep your changes as logically grouped as
+possible within individual commits. There is no limit to the number of commits
+any single Pull Request may have, and many contributors find it easier to review
+changes that are split across multiple commits.
+
+That said, if you have a number of commits that are "checkpoints" and don't
+represent a single logical change, please squash those together.
+
+Note that multiple commits often get squashed when they are landed (see the
+notes about [commit squashing]).
+
+#### Commit message guidelines
+
+A good commit message should describe what changed and why.
+
+1. The first line should:
+
+  * contain a short description of the change (preferably 50 characters or less,
+    and no more than 72 characters)
+  * be entirely in lowercase with the exception of proper nouns, acronyms, and
+    the words that refer to code, like function/variable names
+  * be prefixed with the name of the sub crate being changed (without the `tokio-`
+    prefix) and start with an imperative verb. If modifying `tokio` proper,
+    omit the crate prefix.
+
+  Examples:
+
+  * timer: introduce `Timeout` and deprecate `Deadline`
+  * export `Encoder`, `Decoder`, `Framed*` from tokio_codec
+
+2. Keep the second line blank.
+3. Wrap all other lines at 72 columns (except for long URLs).
+4. If your patch fixes an open issue, you can add a reference to it at the end
+   of the log. Use the `Fixes: #` prefix and the issue number. For other
+   references use `Refs: #`. `Refs` may include multiple issues, separated by a
+   comma.
+
+   Examples:
+
+   - `Fixes: #1337`
+   - `Refs: #1234`
+
+Sample complete commit message:
+
+```txt
+subcrate: explain the commit in one line
+
+Body of commit message is a few lines of text, explaining things
+in more detail, possibly giving some background about the issue
+being fixed, etc.
+
+The body of the commit message can be several paragraphs, and
+please do proper word-wrap and keep columns shorter than about
+72 characters or so. That way, `git log` will show things
+nicely even when it is indented.
+
+Fixes: #1337
+Refs: #453, #154
+```
+
+### Opening the Pull Request
+
+From within GitHub, opening a new Pull Request will present you with a
+[template] that should be filled out. Please try to do your best at filling out
+the details, but feel free to skip parts if you're not sure what to put.
+
+[template]: .github/PULL_REQUEST_TEMPLATE.md
+
+### Discuss and update
+
+You will probably get feedback or requests for changes to your Pull Request.
+This is a big part of the submission process so don't be discouraged! Some
+contributors may sign off on the Pull Request right away, others may have
+more detailed comments or feedback. This is a necessary part of the process
+in order to evaluate whether the changes are correct and necessary.
+
+**Any community member can review a PR and you might get conflicting feedback**.
+Keep an eye out for comments from code owners to provide guidance on conflicting
+feedback.
+
+**Once the PR is open, do not rebase the commits**. See [Commit Squashing] for
+more details.
+
+### Commit Squashing
+
+In most cases, **do not squash commits that you add to your Pull Request during
+the review process**. When the commits in your Pull Request land, they may be
+squashed into one commit per logical change. Metadata will be added to the
+commit message (including links to the Pull Request, links to relevant issues,
+and the names of the reviewers). The commit history of your Pull Request,
+however, will stay intact on the Pull Request page.
+
+## Reviewing Pull Requests
+
+**Any Tokio community member is welcome to review any pull request**.
+
+All Tokio contributors who choose to review and provide feedback on Pull
+Requests have a responsibility to both the project and the individual making the
+contribution. Reviews and feedback must be helpful, insightful, and geared
+towards improving the contribution as opposed to simply blocking it. If there
+are reasons why you feel the PR should not land, explain what those are. Do not
+expect to be able to block a Pull Request from advancing simply because you say
+"No" without giving an explanation. Be open to having your mind changed. Be open
+to working with the contributor to make the Pull Request better.
+
+Reviews that are dismissive or disrespectful of the contributor or any other
+reviewers are strictly counter to the Code of Conduct.
+
+When reviewing a Pull Request, the primary goals are for the codebase to improve
+and for the person submitting the request to succeed. **Even if a Pull Request
+does not land, the submitters should come away from the experience feeling like
+their effort was not wasted or unappreciated**. Every Pull Request from a new
+contributor is an opportunity to grow the community.
+
+### Review a bit at a time.
+
+Do not overwhelm new contributors.
+
+It is tempting to micro-optimize and make everything about relative performance,
+perfect grammar, or exact style matches. Do not succumb to that temptation.
+
+Focus first on the most significant aspects of the change:
+
+1. Does this change make sense for Tokio?
+2. Does this change make Tokio better, even if only incrementally?
+3. Are there clear bugs or larger scale issues that need attending to?
+4. Is the commit message readable and correct? If it contains a breaking change
+   is it clear enough?
+
+Note that only **incremental** improvement is needed to land a PR. This means
+that the PR does not need to be perfect, only better than the status quo. Follow
+up PRs may be opened to continue iterating.
+
+When changes are necessary, *request* them, do not *demand* them, and **do not
+assume that the submitter already knows how to add a test or run a benchmark**.
+
+Specific performance optimization techniques, coding styles and conventions
+change over time. The first impression you give to a new contributor never does.
+
+Nits (requests for small changes that are not essential) are fine, but try to
+avoid stalling the Pull Request. Most nits can typically be fixed by the Tokio
+Collaborator landing the Pull Request but they can also be an opportunity for
+the contributor to learn a bit more about the project.
+
+It is always good to clearly indicate nits when you comment: e.g.
+`Nit: change foo() to bar(). But this is not blocking.`
+
+If your comments were addressed but were not folded automatically after new
+commits or if they proved to be mistaken, please, [hide them][hiding-a-comment]
+with the appropriate reason to keep the conversation flow concise and relevant.
+
+### Be aware of the person behind the code
+
+Be aware that *how* you communicate requests and reviews in your feedback can
+have a significant impact on the success of the Pull Request. Yes, we may land
+a particular change that makes Tokio better, but the individual might just not
+want to have anything to do with Tokio ever again. The goal is not just having
+good code.
+
+### Abandoned or Stalled Pull Requests
+
+If a Pull Request appears to be abandoned or stalled, it is polite to first
+check with the contributor to see if they intend to continue the work before
+checking if they would mind if you took it over (especially if it just has nits
+left). When doing so, it is courteous to give the original contributor credit
+for the work they started (either by preserving their name and email address in
+the commit log, or by using an `Author: ` meta-data tag in the commit.
+
+_Adapted from the [Node.js contributing guide][node]_.
+
+[node]: https://github.com/nodejs/node/blob/master/CONTRIBUTING.md
+[hiding-a-comment]: https://help.github.com/articles/managing-disruptive-comments/#hiding-a-comment
+[documentation test]: https://doc.rust-lang.org/rustdoc/documentation-tests.html

Cargo.toml

@@ -6,11 +6,11 @@ name = "tokio"
 # - Update CHANGELOG.md.
 # - Update doc URL.
 # - Create "v0.1.x" git tag.
-version = "0.1.8"
+version = "0.1.13"
 authors = ["Carl Lerche <[email protected]>"]
 license = "MIT"
 readme = "README.md"
-documentation = "https://docs.rs/tokio/0.1.8/tokio/"
+documentation = "https://docs.rs/tokio/0.1.13/tokio/"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
 description = """
@@ -24,12 +24,16 @@ keywords = ["io", "async", "non-blocking", "futures"]
 
 members = [
   "./",
+  "tokio-async-await",
+  "tokio-buf",
+  "tokio-channel",
   "tokio-codec",
   "tokio-current-thread",
   "tokio-executor",
   "tokio-fs",
   "tokio-io",
   "tokio-reactor",
+  "tokio-signal",
   "tokio-threadpool",
   "tokio-timer",
   "tokio-tcp",
@@ -38,20 +42,29 @@ members = [
   "tokio-uds",
 ]
 
+[features]
+# This feature comes with no promise of stability. Things will
+# break with each patch release. Use at your own risk.
+async-await-preview = [
+  "tokio-async-await/async-await-preview",
+]
+
 [badges]
 travis-ci = { repository = "tokio-rs/tokio" }
 appveyor = { repository = "carllerche/tokio", id = "s83yxhy9qeb58va7" }
 
 [dependencies]
+bytes = "0.4"
+num_cpus = "1.8.0"
 tokio-codec = { version = "0.1.0", path = "tokio-codec" }
-tokio-current-thread = { version = "0.1.1", path = "tokio-current-thread" }
+tokio-current-thread = { version = "0.1.3", path = "tokio-current-thread" }
 tokio-io = { version = "0.1.6", path = "tokio-io" }
-tokio-executor = { version = "0.1.2", path = "tokio-executor" }
+tokio-executor = { version = "0.1.5", path = "tokio-executor" }
 tokio-reactor = { version = "0.1.1", path = "tokio-reactor" }
 tokio-threadpool = { version = "0.1.4", path = "tokio-threadpool" }
 tokio-tcp = { version = "0.1.0", path = "tokio-tcp" }
 tokio-udp = { version = "0.1.0", path = "tokio-udp" }
-tokio-timer = { version = "0.2.6", path = "tokio-timer" }
+tokio-timer = { version = "0.2.8", path = "tokio-timer" }
 tokio-fs = { version = "0.1.3", path = "tokio-fs" }
 
 futures = "0.1.20"
@@ -59,11 +72,13 @@ futures = "0.1.20"
 # Needed until `reactor` is removed from `tokio`.
 mio = "0.6.14"
 
+# Needed for async/await preview support
+tokio-async-await = { version = "0.1.0", path = "tokio-async-await", optional = true }
+
 [target.'cfg(unix)'.dependencies]
-tokio-uds = { version = "0.2.0", path = "tokio-uds" }
+tokio-uds = { version = "0.2.1", path = "tokio-uds" }
 
 [dev-dependencies]
-bytes = "0.4"
 env_logger = { version = "0.5", default-features = false }
 flate2 = { version = "1", features = ["tokio"] }
 futures-cpupool = "0.1"
@@ -75,3 +90,20 @@ serde = "1.0"
 serde_derive = "1.0"
 serde_json = "1.0"
 time = "0.1"
+
+[patch.crates-io]
+tokio = { path = "." }
+tokio-async-await  = { path = "./tokio-async-await" }
+tokio-codec = { path = "./tokio-codec" }
+tokio-current-thread = { path = "./tokio-current-thread" }
+tokio-executor = { path = "./tokio-executor" }
+tokio-fs = { path = "./tokio-fs" }
+tokio-io = { path = "./tokio-io" }
+tokio-reactor = { path = "./tokio-reactor" }
+tokio-signal = { path = "./tokio-signal" }
+tokio-tcp = { path = "./tokio-tcp" }
+tokio-threadpool = { path = "./tokio-threadpool" }
+tokio-timer = { path = "./tokio-timer" }
+tokio-tls = { path = "./tokio-tls" }
+tokio-udp = { path = "./tokio-udp" }
+tokio-uds = { path = "./tokio-uds" }

README.md

@@ -103,6 +103,24 @@ fn main() {
 
 More examples can be found [here](examples).
 
+## Getting Help
+
+First, see if the answer to your question can be found in the [Guides] or the
+[API documentation]. If the answer is not there, there is an active community in
+the [Tokio Gitter channel][chat]. We would be happy to try to answer your
+question.  Last, if that doesn't work, try opening an [issue] with the question.
+
+[chat]: https://gitter.im/tokio-rs/tokio
+[issue]: https://github.com/tokio-rs/tokio/issues/new
+
+## Contributing
+
+:balloon: Thanks for your help improving the project! We are so happy to have
+you! We have a [contributing guide][guide] to help you get involved in the Tokio
+project.
+
+[guide]: CONTRIBUTING.md
+
 ## Project layout
 
 The `tokio` crate, found at the root, is primarily intended for use by
@@ -111,6 +129,8 @@ have greater guarantees of stability.
 
 The crates included as part of Tokio are:
 
+* [`tokio-async-await`]: Experimental `async` / `await` support.
+
 * [`tokio-codec`]: Utilities for encoding and decoding protocol frames.
 
 * [`tokio-current-thread`]: Schedule the execution of futures on the current
@@ -137,6 +157,7 @@ The crates included as part of Tokio are:
 * [`tokio-uds`]: Unix Domain Socket bindings for use with `tokio-io` and
   `tokio-reactor`.
 
+[`tokio-async-await`]: tokio-async-await
 [`tokio-codec`]: tokio-codec
 [`tokio-current-thread`]: tokio-current-thread
 [`tokio-executor`]: tokio-executor
@@ -149,6 +170,14 @@ The crates included as part of Tokio are:
 [`tokio-udp`]: tokio-udp
 [`tokio-uds`]: tokio-uds
 
+## Supported Rust Versions
+
+Tokio is built against the latest stable, nightly, and beta Rust releases. The
+minimum version supported is the stable release from three months before the
+current stable release version. For example, if the latest stable Rust is 1.29,
+the minimum version supported is 1.26. The current Tokio version is not
+guaranteed to build on Rust versions earlier than the minimum supported version.
+
 ## License
 
 This project is licensed under the [MIT license](LICENSE).

ci/tsan

@@ -21,7 +21,7 @@ race:crossbeam_epoch
 race:crossbeam_deque*push
 race:crossbeam_deque*steal
 
-# This filters out expected data race in the treiber stack implementations.
+# This filters out expected data race in the Treiber stack implementations.
 # Treiber stacks are inherently racy. The pop operation will attempt to access
 # the "next" pointer on the node it is attempting to pop. However, at this
 # point it has not gained ownership of the node and another thread might beat
@@ -29,4 +29,9 @@ race:crossbeam_deque*steal
 # original pop operation will fail due to the ABA guard, but tsan still picks
 # up the access on the next pointer.
 race:Backup::next_sleeper
+race:Backup::set_next_sleeper
 race:WorkerEntry::set_next_sleeper
+
+# This ignores a false positive caused by `thread::park()`/`thread::unpark()`.
+# See: https://github.com/rust-lang/rust/pull/54806#issuecomment-436193353
+race:pthread_cond_destroy

examples/chat-combinator.rs

@@ -34,12 +34,12 @@ use std::env;
 use std::io::{BufReader};
 use std::sync::{Arc, Mutex};
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     // Create the TCP listener we'll accept connections on.
     let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
-    let addr = addr.parse().unwrap();
+    let addr = addr.parse()?;
 
-    let socket = TcpListener::bind(&addr).unwrap();
+    let socket = TcpListener::bind(&addr)?;
     println!("Listening on: {}", addr);
 
     // This is running on the Tokio runtime, so it will be multi-threaded. The
@@ -49,10 +49,10 @@ fn main() {
     // The server task asynchronously iterates over and processes each incoming
     // connection.
     let srv = socket.incoming()
-        .map_err(|e| println!("failed to accept socket; error = {:?}", e))
+        .map_err(|e| {println!("failed to accept socket; error = {:?}", e); e})
         .for_each(move |stream| {
             // The client's socket address
-            let addr = stream.peer_addr().unwrap();
+            let addr = stream.peer_addr()?;
 
             println!("New Connection: {}", addr);
 
@@ -143,8 +143,10 @@ fn main() {
             }));
 
             Ok(())
-        });
+        })
+        .map_err(|err| println!("error occurred: {:?}", err));
 
     // execute server
     tokio::run(srv);
+    Ok(())
 }

examples/chat.rs

@@ -426,7 +426,7 @@ fn process(socket: TcpStream, state: Arc<Mutex<Shared>>) {
     tokio::spawn(connection);
 }
 
-pub fn main() {
+pub fn main() -> Result<(), Box<std::error::Error>> {
     // Create the shared state. This is how all the peers communicate.
     //
     // The server task will hold a handle to this. For every new client, the
@@ -434,12 +434,12 @@ pub fn main() {
     // client connection.
     let state = Arc::new(Mutex::new(Shared::new()));
 
-    let addr = "127.0.0.1:6142".parse().unwrap();
+    let addr = "127.0.0.1:6142".parse()?;
 
     // Bind a TCP listener to the socket address.
     //
     // Note that this is the Tokio TcpListener, which is fully async.
-    let listener = TcpListener::bind(&addr).unwrap();
+    let listener = TcpListener::bind(&addr)?;
 
     // The server task asynchronously iterates over and processes each
     // incoming connection.
@@ -471,4 +471,5 @@ pub fn main() {
     // In our example, we have not defined a shutdown strategy, so this will
     // block until `ctrl-c` is pressed at the terminal.
     tokio::run(server);
+    Ok(())
 }

examples/connect.rs

@@ -29,7 +29,7 @@ use std::thread;
 use tokio::prelude::*;
 use futures::sync::mpsc;
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     // Determine if we're going to run in TCP or UDP mode
     let mut args = env::args().skip(1).collect::<Vec<_>>();
     let tcp = match args.iter().position(|a| a == "--udp") {
@@ -41,10 +41,11 @@ fn main() {
     };
 
     // Parse what address we're going to connect to
-    let addr = args.first().unwrap_or_else(|| {
-        panic!("this program requires at least one argument")
-    });
-    let addr = addr.parse::<SocketAddr>().unwrap();
+    let addr = match args.first() {
+        Some(addr) => addr,
+        None => Err("this program requires at least one argument")?,
+    };
+    let addr = addr.parse::<SocketAddr>()?;
 
     // Right now Tokio doesn't support a handle to stdin running on the event
     // loop, so we farm out that work to a separate thread. This thread will
@@ -52,15 +53,15 @@ fn main() {
     // loop over a standard futures channel.
     let (stdin_tx, stdin_rx) = mpsc::channel(0);
     thread::spawn(|| read_stdin(stdin_tx));
-    let stdin_rx = stdin_rx.map_err(|_| panic!()); // errors not possible on rx
+    let stdin_rx = stdin_rx.map_err(|_| panic!("errors not possible on rx"));
 
     // Now that we've got our stdin read we either set up our TCP connection or
     // our UDP connection to get a stream of bytes we're going to emit to
     // stdout.
     let stdout = if tcp {
-        tcp::connect(&addr, Box::new(stdin_rx))
+        tcp::connect(&addr, Box::new(stdin_rx))?
     } else {
-        udp::connect(&addr, Box::new(stdin_rx))
+        udp::connect(&addr, Box::new(stdin_rx))?
     };
 
     // And now with our stream of bytes to write to stdout, we execute that in
@@ -77,6 +78,7 @@ fn main() {
             })
             .map_err(|e| println!("error reading stdout; error = {:?}", e))
     });
+    Ok(())
 }
 
 mod codec {
@@ -127,12 +129,13 @@ mod tcp {
     use bytes::BytesMut;
     use codec::Bytes;
 
+    use std::error::Error;
     use std::io;
     use std::net::SocketAddr;
 
     pub fn connect(addr: &SocketAddr,
                    stdin: Box<Stream<Item = Vec<u8>, Error = io::Error> + Send>)
-        -> Box<Stream<Item = BytesMut, Error = io::Error> + Send>
+        -> Result<Box<Stream<Item = BytesMut, Error = io::Error> + Send>, Box<Error>>
     {
         let tcp = TcpStream::connect(addr);
 
@@ -151,22 +154,24 @@ mod tcp {
         // You'll also note that we *spawn* the work to read stdin and write it
         // to the TCP stream. This is done to ensure that happens concurrently
         // with us reading data from the stream.
-        Box::new(tcp.map(move |stream| {
+        let stream = Box::new(tcp.map(move |stream| {
             let (sink, stream) = Bytes.framed(stream).split();
 
             tokio::spawn(stdin.forward(sink).then(|result| {
                 if let Err(e) = result {
-                    panic!("failed to write to socket: {}", e)
+                    println!("failed to write to socket: {}", e)
                 }
                 Ok(())
             }));
 
             stream
-        }).flatten_stream())
+        }).flatten_stream());
+        Ok(stream)
     }
 }
 
 mod udp {
+    use std::error::Error;
     use std::io;
     use std::net::SocketAddr;
 
@@ -179,17 +184,19 @@ mod udp {
 
     pub fn connect(&addr: &SocketAddr,
                    stdin: Box<Stream<Item = Vec<u8>, Error = io::Error> + Send>)
-        -> Box<Stream<Item = BytesMut, Error = io::Error> + Send>
+        -> Result<Box<Stream<Item = BytesMut, Error = io::Error> + Send>, Box<Error>>
     {
         // We'll bind our UDP socket to a local IP/port, but for now we
         // basically let the OS pick both of those.
         let addr_to_bind = if addr.ip().is_ipv4() {
-            "0.0.0.0:0".parse().unwrap()
+            "0.0.0.0:0".parse()?
         } else {
-            "[::]:0".parse().unwrap()
+            "[::]:0".parse()?
+        };
+        let udp = match UdpSocket::bind(&addr_to_bind) {
+            Ok(udp) => udp,
+            Err(_) => Err("failed to bind socket")?,
         };
-        let udp = UdpSocket::bind(&addr_to_bind)
-            .expect("failed to bind socket");
 
         // Like above with TCP we use an instance of `Bytes` codec to transform
         // this UDP socket into a framed sink/stream which operates over
@@ -203,7 +210,7 @@ mod udp {
             (chunk, addr)
         }).forward(sink).then(|result| {
             if let Err(e) = result {
-                panic!("failed to write to socket: {}", e)
+                println!("failed to write to socket: {}", e)
             }
             Ok(())
         });
@@ -218,10 +225,11 @@ mod udp {
             }
         });
 
-        Box::new(future::lazy(|| {
+        let stream = Box::new(future::lazy(|| {
             tokio::spawn(forward_stdin);
             future::ok(receive)
-        }).flatten_stream())
+        }).flatten_stream());
+        Ok(stream)
     }
 }
 

examples/echo-udp.rs

@@ -1,6 +1,6 @@
 //! An UDP echo server that just sends back everything that it receives.
 //!
-//! If you're on unix you can test this out by in one terminal executing:
+//! If you're on Unix you can test this out by in one terminal executing:
 //!
 //!     cargo run --example echo-udp
 //!
@@ -50,12 +50,12 @@ impl Future for Server {
     }
 }
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
-    let addr = addr.parse::<SocketAddr>().unwrap();
+    let addr = addr.parse::<SocketAddr>()?;
 
-    let socket = UdpSocket::bind(&addr).unwrap();
-    println!("Listening on: {}", socket.local_addr().unwrap());
+    let socket = UdpSocket::bind(&addr)?;
+    println!("Listening on: {}", socket.local_addr()?);
 
     let server = Server {
         socket: socket,
@@ -70,4 +70,5 @@ fn main() {
     //
     // `tokio::run` spawns the task on the Tokio runtime and starts running.
     tokio::run(server.map_err(|e| println!("server error = {:?}", e)));
+    Ok(())
 }

examples/echo.rs

@@ -30,19 +30,19 @@ use tokio::prelude::*;
 use std::env;
 use std::net::SocketAddr;
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     // Allow passing an address to listen on as the first argument of this
     // program, but otherwise we'll just set up our TCP listener on
     // 127.0.0.1:8080 for connections.
     let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
-    let addr = addr.parse::<SocketAddr>().unwrap();
+    let addr = addr.parse::<SocketAddr>()?;
 
     // Next up we create a TCP listener which will listen for incoming
     // connections. This TCP listener is bound to the address we determined
     // above and must be associated with an event loop, so we pass in a handle
     // to our event loop. After the socket's created we inform that we're ready
     // to go and start accepting connections.
-    let socket = TcpListener::bind(&addr).unwrap();
+    let socket = TcpListener::bind(&addr)?;
     println!("Listening on: {}", addr);
 
     // Here we convert the `TcpListener` to a stream of incoming connections
@@ -111,4 +111,5 @@ fn main() {
     // never completes (it just keeps accepting sockets), `tokio::run` blocks
     // forever (until ctrl-c is pressed).
     tokio::run(done);
+    Ok(())
 }

examples/hello_world.rs

@@ -1,59 +1,45 @@
 //! Hello world server.
 //!
-//! A simple server that accepts connections, writes "hello world\n", and closes
+//! A simple client that opens a TCP stream, writes "hello world\n", and closes
 //! the connection.
 //!
 //! You can test this out by running:
 //!
-//!     cargo run --example hello_world
+//!     ncat -l 6142
 //!
 //! And then in another terminal run:
 //!
-//!     telnet localhost 6142
-//!
+//!     cargo run --example hello_world
 
 #![deny(warnings)]
 
 extern crate tokio;
 
 use tokio::io;
-use tokio::net::TcpListener;
+use tokio::net::TcpStream;
 use tokio::prelude::*;
 
-pub fn main() {
-    let addr = "127.0.0.1:6142".parse().unwrap();
+pub fn main() -> Result<(), Box<std::error::Error>> {
+    let addr = "127.0.0.1:6142".parse()?;
 
-    // Bind a TCP listener to the socket address.
+    // Open a TCP stream to the socket address.
     //
-    // Note that this is the Tokio TcpListener, which is fully async.
-    let listener = TcpListener::bind(&addr).unwrap();
-
-    // The server task asynchronously iterates over and processes each
-    // incoming connection.
-    let server = listener.incoming().for_each(|socket| {
-        println!("accepted socket; addr={:?}", socket.peer_addr().unwrap());
-
-        let connection = io::write_all(socket, "hello world\n")
-            .then(|res| {
-                println!("wrote message; success={:?}", res.is_ok());
-                Ok(())
-            });
-
-        // Spawn a new task that processes the socket:
-        tokio::spawn(connection);
-
-        Ok(())
+    // Note that this is the Tokio TcpStream, which is fully async.
+    let client = TcpStream::connect(&addr).and_then(|stream| {
+        println!("created stream");
+        io::write_all(stream, "hello world\n").then(|result| {
+            println!("wrote to stream; success={:?}", result.is_ok());
+            Ok(())
+        })
     })
     .map_err(|err| {
         // All tasks must have an `Error` type of `()`. This forces error
         // handling and helps avoid silencing failures.
         //
         // In our example, we are only going to log the error to STDOUT.
-        println!("accept error = {:?}", err);
+        println!("connection error = {:?}", err);
     });
 
-    println!("server running on localhost:6142");
-
     // Start the Tokio runtime.
     //
     // The Tokio is a pre-configured "out of the box" runtime for building
@@ -63,8 +49,9 @@ pub fn main() {
     // This function blocks until the runtime reaches an idle state. Idle is
     // defined as all spawned tasks have completed and all I/O resources (TCP
     // sockets in our case) have been dropped.
-    //
-    // In our example, we have not defined a shutdown strategy, so this will
-    // block until `ctrl-c` is pressed at the terminal.
-    tokio::run(server);
+    println!("About to create the stream and write to it...");
+    tokio::run(client);
+    println!("Stream has been created and written to.");
+
+    Ok(())
 }

examples/manual-runtime.rs

@@ -60,7 +60,7 @@ fn run<F: Future<Item = (), Error = ()>>(f: F) -> Result<(), IoError> {
     Ok(())
 }
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     run(future::lazy(|| {
         // Here comes the application logic. It can spawn further tasks by tokio_current_thread::spawn().
         // It also can use the default reactor and create timeouts.
@@ -82,5 +82,6 @@ fn main() {
         // We can spawn on the default executor, which is also the local one.
         tokio::executor::spawn(deadline);
         Ok(())
-    })).unwrap();
+    }))?;
+    Ok(())
 }

examples/print_each_packet.rs

@@ -65,19 +65,19 @@ use tokio::codec::Decoder;
 use std::env;
 use std::net::SocketAddr;
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     // Allow passing an address to listen on as the first argument of this
     // program, but otherwise we'll just set up our TCP listener on
     // 127.0.0.1:8080 for connections.
     let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
-    let addr = addr.parse::<SocketAddr>().unwrap();
+    let addr = addr.parse::<SocketAddr>()?;
 
     // Next up we create a TCP listener which will listen for incoming
     // connections. This TCP listener is bound to the address we determined
     // above and must be associated with an event loop, so we pass in a handle
     // to our event loop. After the socket's created we inform that we're ready
     // to go and start accepting connections.
-    let socket = TcpListener::bind(&addr).unwrap();
+    let socket = TcpListener::bind(&addr)?;
     println!("Listening on: {}", addr);
 
     // Here we convert the `TcpListener` to a stream of incoming connections
@@ -146,4 +146,5 @@ fn main() {
     // never completes (it just keeps accepting sockets), `tokio::run` blocks
     // forever (until ctrl-c is pressed).
     tokio::run(done);
+    Ok(())
 }

examples/proxy.rs

@@ -33,15 +33,15 @@ use tokio::io::{copy, shutdown};
 use tokio::net::{TcpListener, TcpStream};
 use tokio::prelude::*;
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     let listen_addr = env::args().nth(1).unwrap_or("127.0.0.1:8081".to_string());
-    let listen_addr = listen_addr.parse::<SocketAddr>().unwrap();
+    let listen_addr = listen_addr.parse::<SocketAddr>()?;
 
     let server_addr = env::args().nth(2).unwrap_or("127.0.0.1:8080".to_string());
-    let server_addr = server_addr.parse::<SocketAddr>().unwrap();
+    let server_addr = server_addr.parse::<SocketAddr>()?;
 
     // Create a TCP listener which will listen for incoming connections.
-    let socket = TcpListener::bind(&listen_addr).unwrap();
+    let socket = TcpListener::bind(&listen_addr)?;
     println!("Listening on: {}", listen_addr);
     println!("Proxying to: {}", server_addr);
 
@@ -94,6 +94,7 @@ fn main() {
         });
 
     tokio::run(done);
+    Ok(())
 }
 
 // This is a custom type used to have a custom implementation of the

examples/tinydb.rs

@@ -56,7 +56,7 @@ use tokio::prelude::*;
 /// The in-memory database shared amongst all clients.
 ///
 /// This database will be shared via `Arc`, so to mutate the internal map we're
-/// also going to use a `RefCell` for interior mutability.
+/// going to use a `Mutex` for interior mutability.
 struct Database {
     map: Mutex<HashMap<String, String>>,
 }
@@ -74,12 +74,12 @@ enum Response {
     Error { msg: String },
 }
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     // Parse the address we're going to run this server on
     // and set up our TCP listener to accept connections.
     let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
-    let addr = addr.parse::<SocketAddr>().unwrap();
-    let listener = TcpListener::bind(&addr).expect("failed to bind");
+    let addr = addr.parse::<SocketAddr>()?;
+    let listener = TcpListener::bind(&addr).map_err(|_| "failed to bind")?;
     println!("Listening on: {}", addr);
 
     // Create the shared state of this server that will be shared amongst all
@@ -156,6 +156,7 @@ fn main() {
         });
 
     tokio::run(done);
+    Ok(())
 }
 
 impl Request {

examples/tinyhttp.rs

@@ -34,13 +34,13 @@ use bytes::BytesMut;
 use http::header::HeaderValue;
 use http::{Request, Response, StatusCode};
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     // Parse the arguments, bind the TCP socket we'll be listening to, spin up
     // our worker threads, and start shipping sockets to those worker threads.
     let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
-    let addr = addr.parse::<SocketAddr>().unwrap();
+    let addr = addr.parse::<SocketAddr>()?;
 
-    let listener = TcpListener::bind(&addr).expect("failed to bind");
+    let listener = TcpListener::bind(&addr)?;
     println!("Listening on: {}", addr);
 
     tokio::run({
@@ -51,6 +51,7 @@ fn main() {
                 Ok(())
             })
     });
+    Ok(())
 }
 
 fn process(socket: TcpStream) {
@@ -84,28 +85,32 @@ fn process(socket: TcpStream) {
 fn respond(req: Request<()>)
     -> Box<Future<Item = Response<String>, Error = io::Error> + Send>
 {
-    let mut ret = Response::builder();
-    let body = match req.uri().path() {
-        "/plaintext" => {
-            ret.header("Content-Type", "text/plain");
-            "Hello, World!".to_string()
-        }
-        "/json" => {
-            ret.header("Content-Type", "application/json");
-
-            #[derive(Serialize)]
-            struct Message {
-                message: &'static str,
+    let f = future::lazy(move || {
+        let mut response = Response::builder();
+        let body = match req.uri().path() {
+            "/plaintext" => {
+                response.header("Content-Type", "text/plain");
+                "Hello, World!".to_string()
             }
-            serde_json::to_string(&Message { message: "Hello, World!" })
-                .unwrap()
-        }
-        _ => {
-            ret.status(StatusCode::NOT_FOUND);
-            String::new()
-        }
-    };
-    Box::new(future::ok(ret.body(body).unwrap()))
+            "/json" => {
+                response.header("Content-Type", "application/json");
+
+                #[derive(Serialize)]
+                struct Message {
+                    message: &'static str,
+                }
+                serde_json::to_string(&Message { message: "Hello, World!" })?
+            }
+            _ => {
+                response.status(StatusCode::NOT_FOUND);
+                String::new()
+            }
+        };
+        let response = response.body(body).map_err(|err| io::Error::new(io::ErrorKind::Other, err))?;
+        Ok(response)
+    });
+
+    Box::new(f)
 }
 
 struct Http;

examples/udp-client.rs

@@ -35,29 +35,27 @@ use std::net::SocketAddr;
 use tokio::net::UdpSocket;
 use tokio::prelude::*;
 
-fn get_stdin_data() -> Vec<u8> {
+fn get_stdin_data() -> Result<Vec<u8>, Box<std::error::Error>> {
     let mut buf = Vec::new();
-    stdin().read_to_end(&mut buf).unwrap();
-    buf
+    stdin().read_to_end(&mut buf)?;
+    Ok(buf)
 }
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     let remote_addr: SocketAddr = env::args()
         .nth(1)
         .unwrap_or("127.0.0.1:8080".into())
-        .parse()
-        .unwrap();
+        .parse()?;
     // We use port 0 to let the operating system allocate an available port for us.
     let local_addr: SocketAddr = if remote_addr.is_ipv4() {
         "0.0.0.0:0"
     } else {
         "[::]:0"
-    }.parse()
-        .unwrap();
-    let socket = UdpSocket::bind(&local_addr).unwrap();
+    }.parse()?;
+    let socket = UdpSocket::bind(&local_addr)?;
     const MAX_DATAGRAM_SIZE: usize = 65_507;
-    let processing = socket
-        .send_dgram(get_stdin_data(), &remote_addr)
+    socket
+        .send_dgram(get_stdin_data()?, &remote_addr)
         .and_then(|(socket, _)| socket.recv_dgram(vec![0u8; MAX_DATAGRAM_SIZE]))
         .map(|(_, data, len, _)| {
             println!(
@@ -66,9 +64,6 @@ fn main() {
                 String::from_utf8_lossy(&data[..len])
             )
         })
-        .wait();
-    match processing {
-        Ok(_) => {}
-        Err(e) => eprintln!("Encountered an error: {}", e),
-    }
+        .wait()?;
+    Ok(())
 }

examples/udp-codec.rs

@@ -19,15 +19,15 @@ use tokio::prelude::*;
 use tokio::net::{UdpSocket, UdpFramed};
 use tokio_codec::BytesCodec;
 
-fn main() {
+fn main() -> Result<(), Box<std::error::Error>> {
     let _ = env_logger::init();
 
-    let addr: SocketAddr = "127.0.0.1:0".parse().unwrap();
+    let addr: SocketAddr = "127.0.0.1:0".parse()?;
 
     // Bind both our sockets and then figure out what ports we got.
-    let a = UdpSocket::bind(&addr).unwrap();
-    let b = UdpSocket::bind(&addr).unwrap();
-    let b_addr = b.local_addr().unwrap();
+    let a = UdpSocket::bind(&addr)?;
+    let b = UdpSocket::bind(&addr)?;
+    let b_addr = b.local_addr()?;
 
     // We're parsing each socket with the `BytesCodec` included in `tokio_io`, and then we
     // `split` each codec into the sink/stream halves.
@@ -61,4 +61,5 @@ fn main() {
             .map(|_| ())
             .map_err(|e| println!("error = {:?}", e))
     });
+    Ok(())
 }

src/async_await.rs

@@ -0,0 +1,26 @@
+use std::future::{Future as StdFuture};
+
+async fn map_ok<T: StdFuture>(future: T) -> Result<(), ()> {
+    let _ = await!(future);
+    Ok(())
+}
+
+/// Like `tokio::run`, but takes an `async` block
+pub fn run_async<F>(future: F)
+where F: StdFuture<Output = ()> + Send + 'static,
+{
+    use tokio_async_await::compat::backward;
+    let future = backward::Compat::new(map_ok(future));
+
+    ::run(future);
+}
+
+/// Like `tokio::spawn`, but takes an `async` block
+pub fn spawn_async<F>(future: F)
+where F: StdFuture<Output = ()> + Send + 'static,
+{
+    use tokio_async_await::compat::backward;
+    let future = backward::Compat::new(map_ok(future));
+
+    ::spawn(future);
+}

src/codec/length_delimited.rs

@@ -0,0 +1,975 @@
+//! Frame a stream of bytes based on a length prefix
+//!
+//! Many protocols delimit their frames by prefacing frame data with a
+//! frame head that specifies the length of the frame. The
+//! `length_delimited` module provides utilities for handling the length
+//! based framing. This allows the consumer to work with entire frames
+//! without having to worry about buffering or other framing logic.
+//!
+//! # Getting started
+//!
+//! If implementing a protocol from scratch, using length delimited framing
+//! is an easy way to get started. [`Codec::new()`] will return a length
+//! delimited codec using default configuration values. This can then be
+//! used to construct a framer to adapt a full-duplex byte stream into a
+//! stream of frames.
+//!
+//! ```
+//! # extern crate tokio;
+//! use tokio::io::{AsyncRead, AsyncWrite};
+//! use tokio::codec::*;
+//!
+//! fn bind_transport<T: AsyncRead + AsyncWrite>(io: T)
+//!     -> Framed<T, LengthDelimitedCodec>
+//! {
+//!     Framed::new(io, LengthDelimitedCodec::new())
+//! }
+//! # pub fn main() {}
+//! ```
+//!
+//! The returned transport implements `Sink + Stream` for `BytesMut`. It
+//! encodes the frame with a big-endian `u32` header denoting the frame
+//! payload length:
+//!
+//! ```text
+//! +----------+--------------------------------+
+//! | len: u32 |          frame payload         |
+//! +----------+--------------------------------+
+//! ```
+//!
+//! Specifically, given the following:
+//!
+//! ```
+//! # extern crate tokio;
+//! # extern crate bytes;
+//! # extern crate futures;
+//! #
+//! use tokio::io::{AsyncRead, AsyncWrite};
+//! use tokio::codec::*;
+//! use bytes::Bytes;
+//! use futures::{Sink, Future};
+//!
+//! fn write_frame<T: AsyncRead + AsyncWrite>(io: T) {
+//!     let mut transport = Framed::new(io, LengthDelimitedCodec::new());
+//!     let frame = Bytes::from("hello world");
+//!
+//!     transport.send(frame).wait().unwrap();
+//! }
+//! #
+//! # pub fn main() {}
+//! ```
+//!
+//! The encoded frame will look like this:
+//!
+//! ```text
+//! +---- len: u32 ----+---- data ----+
+//! | \x00\x00\x00\x0b |  hello world |
+//! +------------------+--------------+
+//! ```
+//!
+//! # Decoding
+//!
+//! [`FramedRead`] adapts an [`AsyncRead`] into a `Stream` of [`BytesMut`],
+//! such that each yielded [`BytesMut`] value contains the contents of an
+//! entire frame. There are many configuration parameters enabling
+//! [`FramedRead`] to handle a wide range of protocols. Here are some
+//! examples that will cover the various options at a high level.
+//!
+//! ## Example 1
+//!
+//! The following will parse a `u16` length field at offset 0, including the
+//! frame head in the yielded `BytesMut`.
+//!
+//! ```
+//! # extern crate tokio;
+//! # use tokio::io::AsyncRead;
+//! # use tokio::codec::length_delimited;
+//! # fn bind_read<T: AsyncRead>(io: T) {
+//! length_delimited::Builder::new()
+//!     .length_field_offset(0) // default value
+//!     .length_field_length(2)
+//!     .length_adjustment(0)   // default value
+//!     .num_skip(0) // Do not strip frame header
+//!     .new_read(io);
+//! # }
+//! # pub fn main() {}
+//! ```
+//!
+//! The following frame will be decoded as such:
+//!
+//! ```text
+//!          INPUT                           DECODED
+//! +-- len ---+--- Payload ---+     +-- len ---+--- Payload ---+
+//! | \x00\x0B |  Hello world  | --> | \x00\x0B |  Hello world  |
+//! +----------+---------------+     +----------+---------------+
+//! ```
+//!
+//! The value of the length field is 11 (`\x0B`) which represents the length
+//! of the payload, `hello world`. By default, [`FramedRead`] assumes that
+//! the length field represents the number of bytes that **follows** the
+//! length field. Thus, the entire frame has a length of 13: 2 bytes for the
+//! frame head + 11 bytes for the payload.
+//!
+//! ## Example 2
+//!
+//! The following will parse a `u16` length field at offset 0, omitting the
+//! frame head in the yielded `BytesMut`.
+//!
+//! ```
+//! # extern crate tokio;
+//! # use tokio::io::AsyncRead;
+//! # use tokio::codec::length_delimited;
+//! # fn bind_read<T: AsyncRead>(io: T) {
+//! length_delimited::Builder::new()
+//!     .length_field_offset(0) // default value
+//!     .length_field_length(2)
+//!     .length_adjustment(0)   // default value
+//!     // `num_skip` is not needed, the default is to skip
+//!     .new_read(io);
+//! # }
+//! # pub fn main() {}
+//! ```
+//!
+//! The following frame will be decoded as such:
+//!
+//! ```text
+//!          INPUT                        DECODED
+//! +-- len ---+--- Payload ---+     +--- Payload ---+
+//! | \x00\x0B |  Hello world  | --> |  Hello world  |
+//! +----------+---------------+     +---------------+
+//! ```
+//!
+//! This is similar to the first example, the only difference is that the
+//! frame head is **not** included in the yielded `BytesMut` value.
+//!
+//! ## Example 3
+//!
+//! The following will parse a `u16` length field at offset 0, including the
+//! frame head in the yielded `BytesMut`. In this case, the length field
+//! **includes** the frame head length.
+//!
+//! ```
+//! # extern crate tokio;
+//! # use tokio::io::AsyncRead;
+//! # use tokio::codec::length_delimited;
+//! # fn bind_read<T: AsyncRead>(io: T) {
+//! length_delimited::Builder::new()
+//!     .length_field_offset(0) // default value
+//!     .length_field_length(2)
+//!     .length_adjustment(-2)  // size of head
+//!     .num_skip(0)
+//!     .new_read(io);
+//! # }
+//! # pub fn main() {}
+//! ```
+//!
+//! The following frame will be decoded as such:
+//!
+//! ```text
+//!          INPUT                           DECODED
+//! +-- len ---+--- Payload ---+     +-- len ---+--- Payload ---+
+//! | \x00\x0D |  Hello world  | --> | \x00\x0D |  Hello world  |
+//! +----------+---------------+     +----------+---------------+
+//! ```
+//!
+//! In most cases, the length field represents the length of the payload
+//! only, as shown in the previous examples. However, in some protocols the
+//! length field represents the length of the whole frame, including the
+//! head. In such cases, we specify a negative `length_adjustment` to adjust
+//! the value provided in the frame head to represent the payload length.
+//!
+//! ## Example 4
+//!
+//! The following will parse a 3 byte length field at offset 0 in a 5 byte
+//! frame head, including the frame head in the yielded `BytesMut`.
+//!
+//! ```
+//! # extern crate tokio;
+//! # use tokio::io::AsyncRead;
+//! # use tokio::codec::length_delimited;
+//! # fn bind_read<T: AsyncRead>(io: T) {
+//! length_delimited::Builder::new()
+//!     .length_field_offset(0) // default value
+//!     .length_field_length(3)
+//!     .length_adjustment(2)  // remaining head
+//!     .num_skip(0)
+//!     .new_read(io);
+//! # }
+//! # pub fn main() {}
+//! ```
+//!
+//! The following frame will be decoded as such:
+//!
+//! ```text
+//!                  INPUT
+//! +---- len -----+- head -+--- Payload ---+
+//! | \x00\x00\x0B | \xCAFE |  Hello world  |
+//! +--------------+--------+---------------+
+//!
+//!                  DECODED
+//! +---- len -----+- head -+--- Payload ---+
+//! | \x00\x00\x0B | \xCAFE |  Hello world  |
+//! +--------------+--------+---------------+
+//! ```
+//!
+//! A more advanced example that shows a case where there is extra frame
+//! head data between the length field and the payload. In such cases, it is
+//! usually desirable to include the frame head as part of the yielded
+//! `BytesMut`. This lets consumers of the length delimited framer to
+//! process the frame head as needed.
+//!
+//! The positive `length_adjustment` value lets `FramedRead` factor in the
+//! additional head into the frame length calculation.
+//!
+//! ## Example 5
+//!
+//! The following will parse a `u16` length field at offset 1 of a 4 byte
+//! frame head. The first byte and the length field will be omitted from the
+//! yielded `BytesMut`, but the trailing 2 bytes of the frame head will be
+//! included.
+//!
+//! ```
+//! # extern crate tokio;
+//! # use tokio::io::AsyncRead;
+//! # use tokio::codec::length_delimited;
+//! # fn bind_read<T: AsyncRead>(io: T) {
+//! length_delimited::Builder::new()
+//!     .length_field_offset(1) // length of hdr1
+//!     .length_field_length(2)
+//!     .length_adjustment(1)  // length of hdr2
+//!     .num_skip(3) // length of hdr1 + LEN
+//!     .new_read(io);
+//! # }
+//! # pub fn main() {}
+//! ```
+//!
+//! The following frame will be decoded as such:
+//!
+//! ```text
+//!                  INPUT
+//! +- hdr1 -+-- len ---+- hdr2 -+--- Payload ---+
+//! |  \xCA  | \x00\x0B |  \xFE  |  Hello world  |
+//! +--------+----------+--------+---------------+
+//!
+//!          DECODED
+//! +- hdr2 -+--- Payload ---+
+//! |  \xFE  |  Hello world  |
+//! +--------+---------------+
+//! ```
+//!
+//! The length field is situated in the middle of the frame head. In this
+//! case, the first byte in the frame head could be a version or some other
+//! identifier that is not needed for processing. On the other hand, the
+//! second half of the head is needed.
+//!
+//! `length_field_offset` indicates how many bytes to skip before starting
+//! to read the length field.  `length_adjustment` is the number of bytes to
+//! skip starting at the end of the length field. In this case, it is the
+//! second half of the head.
+//!
+//! ## Example 6
+//!
+//! The following will parse a `u16` length field at offset 1 of a 4 byte
+//! frame head. The first byte and the length field will be omitted from the
+//! yielded `BytesMut`, but the trailing 2 bytes of the frame head will be
+//! included. In this case, the length field **includes** the frame head
+//! length.
+//!
+//! ```
+//! # extern crate tokio;
+//! # use tokio::io::AsyncRead;
+//! # use tokio::codec::length_delimited;
+//! # fn bind_read<T: AsyncRead>(io: T) {
+//! length_delimited::Builder::new()
+//!     .length_field_offset(1) // length of hdr1
+//!     .length_field_length(2)
+//!     .length_adjustment(-3)  // length of hdr1 + LEN, negative
+//!     .num_skip(3)
+//!     .new_read(io);
+//! # }
+//! # pub fn main() {}
+//! ```
+//!
+//! The following frame will be decoded as such:
+//!
+//! ```text
+//!                  INPUT
+//! +- hdr1 -+-- len ---+- hdr2 -+--- Payload ---+
+//! |  \xCA  | \x00\x0F |  \xFE  |  Hello world  |
+//! +--------+----------+--------+---------------+
+//!
+//!          DECODED
+//! +- hdr2 -+--- Payload ---+
+//! |  \xFE  |  Hello world  |
+//! +--------+---------------+
+//! ```
+//!
+//! Similar to the example above, the difference is that the length field
+//! represents the length of the entire frame instead of just the payload.
+//! The length of `hdr1` and `len` must be counted in `length_adjustment`.
+//! Note that the length of `hdr2` does **not** need to be explicitly set
+//! anywhere because it already is factored into the total frame length that
+//! is read from the byte stream.
+//!
+//! # Encoding
+//!
+//! [`FramedWrite`] adapts an [`AsyncWrite`] into a `Sink` of [`BytesMut`],
+//! such that each submitted [`BytesMut`] is prefaced by a length field.
+//! There are fewer configuration options than [`FramedRead`]. Given
+//! protocols that have more complex frame heads, an encoder should probably
+//! be written by hand using [`Encoder`].
+//!
+//! Here is a simple example, given a `FramedWrite` with the following
+//! configuration:
+//!
+//! ```
+//! # extern crate tokio;
+//! # extern crate bytes;
+//! # use tokio::io::AsyncWrite;
+//! # use tokio::codec::length_delimited;
+//! # use bytes::BytesMut;
+//! # fn write_frame<T: AsyncWrite>(io: T) {
+//! # let _ =
+//! length_delimited::Builder::new()
+//!     .length_field_length(2)
+//!     .new_write(io);
+//! # }
+//! # pub fn main() {}
+//! ```
+//!
+//! A payload of `hello world` will be encoded as:
+//!
+//! ```text
+//! +- len: u16 -+---- data ----+
+//! |  \x00\x0b  |  hello world |
+//! +------------+--------------+
+//! ```
+//!
+//! [`FramedRead`]: struct.FramedRead.html
+//! [`FramedWrite`]: struct.FramedWrite.html
+//! [`AsyncRead`]: ../../trait.AsyncRead.html
+//! [`AsyncWrite`]: ../../trait.AsyncWrite.html
+//! [`Encoder`]: ../trait.Encoder.html
+//! [`BytesMut`]: https://docs.rs/bytes/0.4/bytes/struct.BytesMut.html
+
+use {
+    codec::{
+        Decoder, Encoder, FramedRead, FramedWrite, Framed
+    },
+    io::{
+        AsyncRead, AsyncWrite
+    },
+};
+
+use bytes::{Buf, BufMut, Bytes, BytesMut, IntoBuf};
+
+use std::{cmp, fmt};
+use std::error::Error as StdError;
+use std::io::{self, Cursor};
+
+/// Configure length delimited `LengthDelimitedCodec`s.
+///
+/// `Builder` enables constructing configured length delimited codecs. Note
+/// that not all configuration settings apply to both encoding and decoding. See
+/// the documentation for specific methods for more detail.
+#[derive(Debug, Clone, Copy)]
+pub struct Builder {
+    // Maximum frame length
+    max_frame_len: usize,
+
+    // Number of bytes representing the field length
+    length_field_len: usize,
+
+    // Number of bytes in the header before the length field
+    length_field_offset: usize,
+
+    // Adjust the length specified in the header field by this amount
+    length_adjustment: isize,
+
+    // Total number of bytes to skip before reading the payload, if not set,
+    // `length_field_len + length_field_offset`
+    num_skip: Option<usize>,
+
+    // Length field byte order (little or big endian)
+    length_field_is_big_endian: bool,
+}
+
+/// An error when the number of bytes read is more than max frame length.
+pub struct FrameTooBig {
+    _priv: (),
+}
+
+/// A codec for frames delimited by a frame head specifying their lengths.
+///
+/// This allows the consumer to work with entire frames without having to worry
+/// about buffering or other framing logic.
+///
+/// See [module level] documentation for more detail.
+///
+/// [module level]: index.html
+#[derive(Debug)]
+pub struct LengthDelimitedCodec {
+    // Configuration values
+    builder: Builder,
+
+    // Read state
+    state: DecodeState,
+}
+
+#[derive(Debug, Clone, Copy)]
+enum DecodeState {
+    Head,
+    Data(usize),
+}
+
+// ===== impl LengthDelimitedCodec ======
+
+impl LengthDelimitedCodec {
+    /// Creates a new `LengthDelimitedCodec` with the default configuration values.
+    pub fn new() -> Self {
+        Self {
+            builder: Builder::new(),
+            state: DecodeState::Head,
+        }
+    }
+
+    /// Returns the current max frame setting
+    ///
+    /// This is the largest size this codec will accept from the wire. Larger
+    /// frames will be rejected.
+    pub fn max_frame_length(&self) -> usize {
+        self.builder.max_frame_len
+    }
+
+    /// Updates the max frame setting.
+    ///
+    /// The change takes effect the next time a frame is decoded. In other
+    /// words, if a frame is currently in process of being decoded with a frame
+    /// size greater than `val` but less than the max frame length in effect
+    /// before calling this function, then the frame will be allowed.
+    pub fn set_max_frame_length(&mut self, val: usize) {
+        self.builder.max_frame_length(val);
+    }
+
+    fn decode_head(&mut self, src: &mut BytesMut) -> io::Result<Option<usize>> {
+        let head_len = self.builder.num_head_bytes();
+        let field_len = self.builder.length_field_len;
+
+        if src.len() < head_len {
+            // Not enough data
+            return Ok(None);
+        }
+
+        let n = {
+            let mut src = Cursor::new(&mut *src);
+
+            // Skip the required bytes
+            src.advance(self.builder.length_field_offset);
+
+            // match endianess
+            let n = if self.builder.length_field_is_big_endian {
+                src.get_uint_be(field_len)
+            } else {
+                src.get_uint_le(field_len)
+            };
+
+            if n > self.builder.max_frame_len as u64 {
+                return Err(io::Error::new(io::ErrorKind::InvalidData, FrameTooBig {
+                    _priv: (),
+                }));
+            }
+
+            // The check above ensures there is no overflow
+            let n = n as usize;
+
+            // Adjust `n` with bounds checking
+            let n = if self.builder.length_adjustment < 0 {
+                n.checked_sub(-self.builder.length_adjustment as usize)
+            } else {
+                n.checked_add(self.builder.length_adjustment as usize)
+            };
+
+            // Error handling
+            match n {
+                Some(n) => n,
+                None => return Err(io::Error::new(io::ErrorKind::InvalidInput, "provided length would overflow after adjustment")),
+            }
+        };
+
+        let num_skip = self.builder.get_num_skip();
+
+        if num_skip > 0 {
+            let _ = src.split_to(num_skip);
+        }
+
+        // Ensure that the buffer has enough space to read the incoming
+        // payload
+        src.reserve(n);
+
+        return Ok(Some(n));
+    }
+
+    fn decode_data(&self, n: usize, src: &mut BytesMut) -> io::Result<Option<BytesMut>> {
+        // At this point, the buffer has already had the required capacity
+        // reserved. All there is to do is read.
+        if src.len() < n {
+            return Ok(None);
+        }
+
+        Ok(Some(src.split_to(n)))
+    }
+}
+
+impl Decoder for LengthDelimitedCodec {
+    type Item = BytesMut;
+    type Error = io::Error;
+
+    fn decode(&mut self, src: &mut BytesMut) -> io::Result<Option<BytesMut>> {
+        let n = match self.state {
+            DecodeState::Head => {
+                match try!(self.decode_head(src)) {
+                    Some(n) => {
+                        self.state = DecodeState::Data(n);
+                        n
+                    }
+                    None => return Ok(None),
+                }
+            }
+            DecodeState::Data(n) => n,
+        };
+
+        match try!(self.decode_data(n, src)) {
+            Some(data) => {
+                // Update the decode state
+                self.state = DecodeState::Head;
+
+                // Make sure the buffer has enough space to read the next head
+                src.reserve(self.builder.num_head_bytes());
+
+                Ok(Some(data))
+            }
+            None => Ok(None),
+        }
+    }
+}
+
+impl Encoder for LengthDelimitedCodec {
+    type Item = Bytes;
+    type Error = io::Error;
+
+    fn encode(&mut self, data: Bytes, dst: &mut BytesMut) -> Result<(), io::Error> {
+        let n = (&data).into_buf().remaining();
+
+        if n > self.builder.max_frame_len {
+            return Err(io::Error::new(io::ErrorKind::InvalidInput, FrameTooBig {
+                _priv: (),
+            }));
+        }
+
+        // Adjust `n` with bounds checking
+        let n = if self.builder.length_adjustment < 0 {
+            n.checked_add(-self.builder.length_adjustment as usize)
+        } else {
+            n.checked_sub(self.builder.length_adjustment as usize)
+        };
+
+        let n = n.ok_or_else(|| io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "provided length would overflow after adjustment",
+        ))?;
+
+        // Reserve capacity in the destination buffer to fit the frame and
+        // length field (plus adjustment).
+        dst.reserve(self.builder.length_field_len + n);
+
+        if self.builder.length_field_is_big_endian {
+            dst.put_uint_be(n as u64, self.builder.length_field_len);
+        } else {
+            dst.put_uint_le(n as u64, self.builder.length_field_len);
+        }
+
+        // Write the frame to the buffer
+        dst.extend_from_slice(&data[..]);
+
+        Ok(())
+    }
+}
+
+// ===== impl Builder =====
+
+impl Builder {
+    /// Creates a new length delimited codec builder with default configuration
+    /// values.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    ///
+    /// # fn bind_read<T: AsyncRead>(io: T) {
+    /// Builder::new()
+    ///     .length_field_offset(0)
+    ///     .length_field_length(2)
+    ///     .length_adjustment(0)
+    ///     .num_skip(0)
+    ///     .new_read(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn new() -> Builder {
+        Builder {
+            // Default max frame length of 8MB
+            max_frame_len: 8 * 1_024 * 1_024,
+
+            // Default byte length of 4
+            length_field_len: 4,
+
+            // Default to the header field being at the start of the header.
+            length_field_offset: 0,
+
+            length_adjustment: 0,
+
+            // Total number of bytes to skip before reading the payload, if not set,
+            // `length_field_len + length_field_offset`
+            num_skip: None,
+
+            // Default to reading the length field in network (big) endian.
+            length_field_is_big_endian: true,
+        }
+    }
+
+    /// Read the length field as a big endian integer
+    ///
+    /// This is the default setting.
+    ///
+    /// This configuration option applies to both encoding and decoding.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    ///
+    /// # fn bind_read<T: AsyncRead>(io: T) {
+    /// Builder::new()
+    ///     .big_endian()
+    ///     .new_read(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn big_endian(&mut self) -> &mut Self {
+        self.length_field_is_big_endian = true;
+        self
+    }
+
+    /// Read the length field as a little endian integer
+    ///
+    /// The default setting is big endian.
+    ///
+    /// This configuration option applies to both encoding and decoding.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    ///
+    /// # fn bind_read<T: AsyncRead>(io: T) {
+    /// Builder::new()
+    ///     .little_endian()
+    ///     .new_read(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn little_endian(&mut self) -> &mut Self {
+        self.length_field_is_big_endian = false;
+        self
+    }
+
+    /// Read the length field as a native endian integer
+    ///
+    /// The default setting is big endian.
+    ///
+    /// This configuration option applies to both encoding and decoding.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    ///
+    /// # fn bind_read<T: AsyncRead>(io: T) {
+    /// Builder::new()
+    ///     .native_endian()
+    ///     .new_read(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn native_endian(&mut self) -> &mut Self {
+        if cfg!(target_endian = "big") {
+            self.big_endian()
+        } else {
+            self.little_endian()
+        }
+    }
+
+    /// Sets the max frame length
+    ///
+    /// This configuration option applies to both encoding and decoding. The
+    /// default value is 8MB.
+    ///
+    /// When decoding, the length field read from the byte stream is checked
+    /// against this setting **before** any adjustments are applied. When
+    /// encoding, the length of the submitted payload is checked against this
+    /// setting.
+    ///
+    /// When frames exceed the max length, an `io::Error` with the custom value
+    /// of the `FrameTooBig` type will be returned.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    ///
+    /// # fn bind_read<T: AsyncRead>(io: T) {
+    /// Builder::new()
+    ///     .max_frame_length(8 * 1024)
+    ///     .new_read(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn max_frame_length(&mut self, val: usize) -> &mut Self {
+        self.max_frame_len = val;
+        self
+    }
+
+    /// Sets the number of bytes used to represent the length field
+    ///
+    /// The default value is `4`. The max value is `8`.
+    ///
+    /// This configuration option applies to both encoding and decoding.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    ///
+    /// # fn bind_read<T: AsyncRead>(io: T) {
+    /// Builder::new()
+    ///     .length_field_length(4)
+    ///     .new_read(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn length_field_length(&mut self, val: usize) -> &mut Self {
+        assert!(val > 0 && val <= 8, "invalid length field length");
+        self.length_field_len = val;
+        self
+    }
+
+    /// Sets the number of bytes in the header before the length field
+    ///
+    /// This configuration option only applies to decoding.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    ///
+    /// # fn bind_read<T: AsyncRead>(io: T) {
+    /// Builder::new()
+    ///     .length_field_offset(1)
+    ///     .new_read(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn length_field_offset(&mut self, val: usize) -> &mut Self {
+        self.length_field_offset = val;
+        self
+    }
+
+    /// Delta between the payload length specified in the header and the real
+    /// payload length
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    ///
+    /// # fn bind_read<T: AsyncRead>(io: T) {
+    /// Builder::new()
+    ///     .length_adjustment(-2)
+    ///     .new_read(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn length_adjustment(&mut self, val: isize) -> &mut Self {
+        self.length_adjustment = val;
+        self
+    }
+
+    /// Sets the number of bytes to skip before reading the payload
+    ///
+    /// Default value is `length_field_len + length_field_offset`
+    ///
+    /// This configuration option only applies to decoding
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    ///
+    /// # fn bind_read<T: AsyncRead>(io: T) {
+    /// Builder::new()
+    ///     .num_skip(4)
+    ///     .new_read(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn num_skip(&mut self, val: usize) -> &mut Self {
+        self.num_skip = Some(val);
+        self
+    }
+
+    /// Create a configured length delimited `LengthDelimitedCodec`
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    /// # pub fn main() {
+    /// Builder::new()
+    ///     .length_field_offset(0)
+    ///     .length_field_length(2)
+    ///     .length_adjustment(0)
+    ///     .num_skip(0)
+    ///     .new_codec();
+    /// # }
+    /// ```
+    pub fn new_codec(&self) -> LengthDelimitedCodec {
+        LengthDelimitedCodec {
+            builder: *self,
+            state: DecodeState::Head,
+        }
+    }
+
+    /// Create a configured length delimited `FramedRead`
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # use tokio::io::AsyncRead;
+    /// use tokio::codec::length_delimited::Builder;
+    ///
+    /// # fn bind_read<T: AsyncRead>(io: T) {
+    /// Builder::new()
+    ///     .length_field_offset(0)
+    ///     .length_field_length(2)
+    ///     .length_adjustment(0)
+    ///     .num_skip(0)
+    ///     .new_read(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn new_read<T>(&self, upstream: T) -> FramedRead<T, LengthDelimitedCodec>
+        where T: AsyncRead,
+    {
+        FramedRead::new(upstream, self.new_codec())
+    }
+
+    /// Create a configured length delimited `FramedWrite`
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # extern crate bytes;
+    /// # use tokio::io::AsyncWrite;
+    /// # use tokio::codec::length_delimited;
+    /// # use bytes::BytesMut;
+    /// # fn write_frame<T: AsyncWrite>(io: T) {
+    /// length_delimited::Builder::new()
+    ///     .length_field_length(2)
+    ///     .new_write(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn new_write<T>(&self, inner: T) -> FramedWrite<T, LengthDelimitedCodec>
+        where T: AsyncWrite,
+    {
+        FramedWrite::new(inner, self.new_codec())
+    }
+
+    /// Create a configured length delimited `Framed`
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # extern crate bytes;
+    /// # use tokio::io::{AsyncRead, AsyncWrite};
+    /// # use tokio::codec::length_delimited;
+    /// # use bytes::BytesMut;
+    /// # fn write_frame<T: AsyncRead + AsyncWrite>(io: T) {
+    /// # let _ =
+    /// length_delimited::Builder::new()
+    ///     .length_field_length(2)
+    ///     .new_framed(io);
+    /// # }
+    /// # pub fn main() {}
+    /// ```
+    pub fn new_framed<T>(&self, inner: T) -> Framed<T, LengthDelimitedCodec>
+        where T: AsyncRead + AsyncWrite,
+    {
+        Framed::new(inner, self.new_codec())
+    }
+
+    fn num_head_bytes(&self) -> usize {
+        let num = self.length_field_offset + self.length_field_len;
+        cmp::max(num, self.num_skip.unwrap_or(0))
+    }
+
+    fn get_num_skip(&self) -> usize {
+        self.num_skip.unwrap_or(self.length_field_offset + self.length_field_len)
+    }
+}
+
+
+// ===== impl FrameTooBig =====
+
+impl fmt::Debug for FrameTooBig {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("FrameTooBig")
+            .finish()
+    }
+}
+
+impl fmt::Display for FrameTooBig {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str(self.description())
+    }
+}
+
+impl StdError for FrameTooBig {
+    fn description(&self) -> &str {
+        "frame size too big"
+    }
+}

src/codec/mod.rs

@@ -0,0 +1,26 @@
+//! Utilities for encoding and decoding frames.
+//!
+//! Contains adapters to go from streams of bytes, [`AsyncRead`] and
+//! [`AsyncWrite`], to framed streams implementing [`Sink`] and [`Stream`].
+//! Framed streams are also known as [transports].
+//!
+//! [`AsyncRead`]: ../io/trait.AsyncRead.html
+//! [`AsyncWrite`]: ../io/trait.AsyncWrite.html
+//! [`Sink`]: https://docs.rs/futures/0.1/futures/sink/trait.Sink.html
+//! [`Stream`]: https://docs.rs/futures/0.1/futures/stream/trait.Stream.html
+//! [transports]: https://tokio.rs/docs/going-deeper/frames/
+
+pub use tokio_codec::{
+    Decoder,
+    Encoder,
+    Framed,
+    FramedParts,
+    FramedRead,
+    FramedWrite,
+    BytesCodec,
+    LinesCodec,
+};
+
+pub mod length_delimited;
+
+pub use self::length_delimited::LengthDelimitedCodec;

src/executor/mod.rs

@@ -39,11 +39,15 @@
 //! [`Executor`]: trait.Executor.html
 //! [`spawn`]: fn.spawn.html
 
-#[deprecated(since = "0.1.8", note = "use tokio-current-thread crate instead")]
+#[deprecated(
+    since = "0.1.8",
+    note = "use tokio-current-thread crate or functions in tokio::runtime::current_thread instead",
+)]
 #[doc(hidden)]
 pub mod current_thread;
 
 #[deprecated(since = "0.1.8", note = "use tokio-threadpool crate instead")]
+#[doc(hidden)]
 /// Re-exports of [`tokio-threadpool`], deprecated in favor of the crate.
 ///
 /// [`tokio-threadpool`]: https://docs.rs/tokio-threadpool/0.1

src/io.rs

@@ -0,0 +1,94 @@
+//! Asynchronous I/O.
+//!
+//! This module is the asynchronous version of `std::io`. Primarily, it
+//! defines two traits, [`AsyncRead`] and [`AsyncWrite`], which extend the
+//! `Read` and `Write` traits of the standard library.
+//!
+//! # AsyncRead and AsyncWrite
+//!
+//! [`AsyncRead`] and [`AsyncWrite`] must only be implemented for
+//! non-blocking I/O types that integrate with the futures type system. In
+//! other words, these types must never block the thread, and instead the
+//! current task is notified when the I/O resource is ready.
+//!
+//! # Standard input and output
+//!
+//! Tokio provides asynchronous APIs to standard [input], [output], and [error].
+//! These APIs are very similar to the ones provided by `std`, but they also
+//! implement [`AsyncRead`] and [`AsyncWrite`].
+//!
+//! Unlike *most* other Tokio APIs, the standard input / output APIs
+//! **must** be used from the context of the Tokio runtime as they require
+//! Tokio specific features to function.
+//!
+//! [input]: fn.stdin.html
+//! [output]: fn.stdout.html
+//! [error]: fn.stderr.html
+//!
+//! # Utility functions
+//!
+//! Utilities functions are provided for working with [`AsyncRead`] /
+//! [`AsyncWrite`] types. For example, [`copy`] asynchronously copies all
+//! data from a source to a destination.
+//!
+//! # `std` re-exports
+//!
+//! Additionally, [`Read`], [`Write`], [`Error`], [`ErrorKind`], and
+//! [`Result`] are re-exported from `std::io` for ease of use.
+//!
+//! [`AsyncRead`]: trait.AsyncRead.html
+//! [`AsyncWrite`]: trait.AsyncWrite.html
+//! [`copy`]: fn.copy.html
+//! [`Read`]: trait.Read.html
+//! [`Write`]: trait.Write.html
+//! [`Error`]: struct.Error.html
+//! [`ErrorKind`]: enum.ErrorKind.html
+//! [`Result`]: type.Result.html
+
+pub use tokio_io::{
+    AsyncRead,
+    AsyncWrite,
+};
+
+// standard input, output, and error
+pub use tokio_fs::{
+    stdin,
+    Stdin,
+    stdout,
+    Stdout,
+    stderr,
+    Stderr,
+};
+
+// Utils
+pub use tokio_io::io::{
+    copy,
+    Copy,
+    flush,
+    Flush,
+    lines,
+    Lines,
+    read,
+    read_exact,
+    ReadExact,
+    read_to_end,
+    ReadToEnd,
+    read_until,
+    ReadUntil,
+    ReadHalf,
+    shutdown,
+    Shutdown,
+    write_all,
+    WriteAll,
+    WriteHalf,
+};
+
+// Re-export io::Error so that users don't have to deal
+// with conflicts when `use`ing `futures::io` and `std::io`.
+pub use ::std::io::{
+    Error,
+    ErrorKind,
+    Result,
+    Read,
+    Write,
+};

src/lib.rs

@@ -1,3 +1,11 @@
+#![doc(html_root_url = "https://docs.rs/tokio/0.1.13")]
+#![deny(missing_docs, warnings, missing_debug_implementations)]
+#![cfg_attr(feature = "async-await-preview", feature(
+        async_await,
+        await_macro,
+        futures_api,
+        ))]
+
 //! A runtime for writing reliable, asynchronous, and slim applications.
 //!
 //! Tokio is an event-driven, non-blocking I/O platform for writing asynchronous
@@ -64,12 +72,11 @@
 //! }
 //! ```
 
-#![doc(html_root_url = "https://docs.rs/tokio/0.1.5")]
-#![deny(missing_docs, warnings, missing_debug_implementations)]
-
+extern crate bytes;
 #[macro_use]
 extern crate futures;
 extern crate mio;
+extern crate num_cpus;
 extern crate tokio_current_thread;
 extern crate tokio_io;
 extern crate tokio_executor;
@@ -81,13 +88,19 @@ extern crate tokio_timer;
 extern crate tokio_tcp;
 extern crate tokio_udp;
 
+#[cfg(feature = "async-await-preview")]
+extern crate tokio_async_await;
+
 #[cfg(unix)]
 extern crate tokio_uds;
 
 pub mod clock;
+pub mod codec;
 pub mod executor;
 pub mod fs;
+pub mod io;
 pub mod net;
+pub mod prelude;
 pub mod reactor;
 pub mod runtime;
 pub mod timer;
@@ -96,164 +109,13 @@ pub mod util;
 pub use executor::spawn;
 pub use runtime::run;
 
-pub mod codec {
-    //! Utilities for encoding and decoding frames.
-    //!
-    //! Contains adapters to go from streams of bytes, [`AsyncRead`] and
-    //! [`AsyncWrite`], to framed streams implementing [`Sink`] and [`Stream`].
-    //! Framed streams are also known as [transports].
-    //!
-    //! [`AsyncRead`]: ../io/trait.AsyncRead.html
-    //! [`AsyncWrite`]: ../io/trait.AsyncWrite.html
-    //! [`Sink`]: https://docs.rs/futures/0.1/futures/sink/trait.Sink.html
-    //! [`Stream`]: https://docs.rs/futures/0.1/futures/stream/trait.Stream.html
-    //! [transports]: https://tokio.rs/docs/going-deeper/frames/
+// ===== Experimental async/await support =====
 
-    pub use tokio_codec::{
-        Decoder,
-        Encoder,
-        Framed,
-        FramedParts,
-        FramedRead,
-        FramedWrite,
-        BytesCodec,
-        LinesCodec,
-    };
-}
+#[cfg(feature = "async-await-preview")]
+mod async_await;
 
-pub mod io {
-    //! Asynchronous I/O.
-    //!
-    //! This module is the asynchronous version of `std::io`. Primarily, it
-    //! defines two traits, [`AsyncRead`] and [`AsyncWrite`], which extend the
-    //! `Read` and `Write` traits of the standard library.
-    //!
-    //! # AsyncRead and AsyncWrite
-    //!
-    //! [`AsyncRead`] and [`AsyncWrite`] must only be implemented for
-    //! non-blocking I/O types that integrate with the futures type system. In
-    //! other words, these types must never block the thread, and instead the
-    //! current task is notified when the I/O resource is ready.
-    //!
-    //! # Standard input and output
-    //!
-    //! Tokio provides asynchronous APIs to standard [input], [output], and [error].
-    //! These APIs are very similar to the ones provided by `std`, but they also
-    //! implement [`AsyncRead`] and [`AsyncWrite`].
-    //!
-    //! Unlike *most* other Tokio APIs, the standard input / output APIs
-    //! **must** be used from the context of the Tokio runtime as they require
-    //! Tokio specific features to function.
-    //!
-    //! [input]: fn.stdin.html
-    //! [output]: fn.stdout.html
-    //! [error]: fn.stderr.html
-    //!
-    //! # Utility functions
-    //!
-    //! Utilities functions are provided for working with [`AsyncRead`] /
-    //! [`AsyncWrite`] types. For example, [`copy`] asynchronously copies all
-    //! data from a source to a destination.
-    //!
-    //! # `std` re-exports
-    //!
-    //! Additionally, [`Read`], [`Write`], [`Error`], [`ErrorKind`], and
-    //! [`Result`] are re-exported from `std::io` for ease of use.
-    //!
-    //! [`AsyncRead`]: trait.AsyncRead.html
-    //! [`AsyncWrite`]: trait.AsyncWrite.html
-    //! [`copy`]: fn.copy.html
-    //! [`Read`]: trait.Read.html
-    //! [`Write`]: trait.Write.html
-    //! [`Error`]: struct.Error.html
-    //! [`ErrorKind`]: enum.ErrorKind.html
-    //! [`Result`]: type.Result.html
+#[cfg(feature = "async-await-preview")]
+pub use async_await::{run_async, spawn_async};
 
-    pub use tokio_io::{
-        AsyncRead,
-        AsyncWrite,
-    };
-
-    // standard input, output, and error
-    pub use tokio_fs::{
-        stdin,
-        Stdin,
-        stdout,
-        Stdout,
-        stderr,
-        Stderr,
-    };
-
-    // Utils
-    pub use tokio_io::io::{
-        copy,
-        Copy,
-        flush,
-        Flush,
-        lines,
-        Lines,
-        read_exact,
-        ReadExact,
-        read_to_end,
-        ReadToEnd,
-        read_until,
-        ReadUntil,
-        ReadHalf,
-        shutdown,
-        Shutdown,
-        write_all,
-        WriteAll,
-        WriteHalf,
-    };
-
-    // Re-export io::Error so that users don't have to deal
-    // with conflicts when `use`ing `futures::io` and `std::io`.
-    pub use ::std::io::{
-        Error,
-        ErrorKind,
-        Result,
-        Read,
-        Write,
-    };
-}
-
-pub mod prelude {
-    //! A "prelude" for users of the `tokio` crate.
-    //!
-    //! This prelude is similar to the standard library's prelude in that you'll
-    //! almost always want to import its entire contents, but unlike the standard
-    //! library's prelude you'll have to do so manually:
-    //!
-    //! ```
-    //! use tokio::prelude::*;
-    //! ```
-    //!
-    //! The prelude may grow over time as additional items see ubiquitous use.
-
-    pub use tokio_io::{
-        AsyncRead,
-        AsyncWrite,
-    };
-
-    pub use util::{
-        FutureExt,
-    };
-
-    pub use ::std::io::{
-        Read,
-        Write,
-    };
-
-    pub use futures::{
-        Future,
-        future,
-        Stream,
-        stream,
-        Sink,
-        IntoFuture,
-        Async,
-        AsyncSink,
-        Poll,
-        task,
-    };
-}
+#[cfg(feature = "async-await-preview")]
+pub use tokio_async_await::await;

src/net.rs

@@ -1,54 +1,85 @@
-//! TCP/UDP bindings for `tokio`.
+//! TCP/UDP/Unix bindings for `tokio`.
 //!
-//! This module contains the TCP/UDP networking types, similar to the standard
+//! This module contains the TCP/UDP/Unix networking types, similar to the standard
 //! library, which can be used to implement networking protocols.
 //!
-//! # TCP
+//! # Organization
 //!
-//! Connecting to an address, via TCP, can be done using [`TcpStream`]'s
-//! [`connect`] method, which returns [`ConnectFuture`]. `ConnectFuture`
-//! implements a future which returns a `TcpStream`.
+//! * [`TcpListener`] and [`TcpStream`] provide functionality for communication over TCP
+//! * [`UdpSocket`] and [`UdpFramed`] provide functionality for communication over UDP
+//! * [`UnixListener`] and [`UnixStream`] provide functionality for communication over a
+//! Unix Domain Socket **(available on Unix only)**
 //!
-//! To listen on an address [`TcpListener`] can be used. `TcpListener`'s
-//! [`incoming`][incoming_method] method can be used to accept new connections.
-//! It return the [`Incoming`] struct, which implements a stream which returns
-//! `TcpStream`s.
-//!
-//! [`TcpStream`]: struct.TcpStream.html
-//! [`connect`]: struct.TcpStream.html#method.connect
-//! [`ConnectFuture`]: struct.ConnectFuture.html
 //! [`TcpListener`]: struct.TcpListener.html
-//! [incoming_method]: struct.TcpListener.html#method.incoming
-//! [`Incoming`]: struct.Incoming.html
-//!
-//! # UDP
-//!
-//! The main struct for UDP is the [`UdpSocket`], which represents a UDP socket.
-//! Reading and writing to it can be done using futures, which return the
-//! [`RecvDgram`] and [`SendDgram`] structs respectively.
-//!
-//! For convenience it's also possible to convert raw datagrams into higher-level
-//! frames.
-//!
+//! [`TcpStream`]: struct.TcpStream.html
 //! [`UdpSocket`]: struct.UdpSocket.html
-//! [`RecvDgram`]: struct.RecvDgram.html
-//! [`SendDgram`]: struct.SendDgram.html
 //! [`UdpFramed`]: struct.UdpFramed.html
-//! [`framed`]: struct.UdpSocket.html#method.framed
+//! [`UnixListener`]: struct.UnixListener.html
+//! [`UnixStream`]: struct.UnixStream.html
 
-pub use tokio_tcp::{TcpStream, ConnectFuture};
-pub use tokio_tcp::{TcpListener, Incoming};
-pub use tokio_udp::{UdpSocket, UdpFramed, SendDgram, RecvDgram};
+pub mod tcp {
+    //! TCP bindings for `tokio`.
+    //!
+    //! Connecting to an address, via TCP, can be done using [`TcpStream`]'s
+    //! [`connect`] method, which returns [`ConnectFuture`]. `ConnectFuture`
+    //! implements a future which returns a `TcpStream`.
+    //!
+    //! To listen on an address [`TcpListener`] can be used. `TcpListener`'s
+    //! [`incoming`][incoming_method] method can be used to accept new connections.
+    //! It return the [`Incoming`] struct, which implements a stream which returns
+    //! `TcpStream`s.
+    //!
+    //! [`TcpStream`]: struct.TcpStream.html
+    //! [`connect`]: struct.TcpStream.html#method.connect
+    //! [`ConnectFuture`]: struct.ConnectFuture.html
+    //! [`TcpListener`]: struct.TcpListener.html
+    //! [incoming_method]: struct.TcpListener.html#method.incoming
+    //! [`Incoming`]: struct.Incoming.html
+    pub use tokio_tcp::{ConnectFuture, Incoming, TcpListener, TcpStream};
+}
+pub use self::tcp::{TcpListener, TcpStream};
+
+#[deprecated(note = "use `tokio::net::tcp::ConnectFuture` instead")]
+#[doc(hidden)]
+pub type ConnectFuture = self::tcp::ConnectFuture;
+#[deprecated(note = "use `tokio::net::tcp::Incoming` instead")]
+#[doc(hidden)]
+pub type Incoming = self::tcp::Incoming;
+
+pub mod udp {
+    //! UDP bindings for `tokio`.
+    //!
+    //! The main struct for UDP is the [`UdpSocket`], which represents a UDP socket.
+    //! Reading and writing to it can be done using futures, which return the
+    //! [`RecvDgram`] and [`SendDgram`] structs respectively.
+    //!
+    //! For convenience it's also possible to convert raw datagrams into higher-level
+    //! frames.
+    //!
+    //! [`UdpSocket`]: struct.UdpSocket.html
+    //! [`RecvDgram`]: struct.RecvDgram.html
+    //! [`SendDgram`]: struct.SendDgram.html
+    //! [`UdpFramed`]: struct.UdpFramed.html
+    //! [`framed`]: struct.UdpSocket.html#method.framed
+    pub use tokio_udp::{RecvDgram, SendDgram, UdpFramed, UdpSocket};
+}
+pub use self::udp::{UdpFramed, UdpSocket};
+
+#[deprecated(note = "use `tokio::net::udp::RecvDgram` instead")]
+#[doc(hidden)]
+pub type RecvDgram<T> = self::udp::RecvDgram<T>;
+#[deprecated(note = "use `tokio::net::udp::SendDgram` instead")]
+#[doc(hidden)]
+pub type SendDgram<T> = self::udp::SendDgram<T>;
 
 #[cfg(unix)]
 pub mod unix {
-    //! Unix domain socket bindings for `tokio`.
+    //! Unix domain socket bindings for `tokio` (only available on unix systems).
 
     pub use tokio_uds::{
         ConnectFuture, Incoming, RecvDgram, SendDgram, UCred, UnixDatagram, UnixListener,
         UnixStream,
     };
 }
-
 #[cfg(unix)]
 pub use self::unix::{UnixListener, UnixStream};

src/prelude.rs

@@ -0,0 +1,54 @@
+//! A "prelude" for users of the `tokio` crate.
+//!
+//! This prelude is similar to the standard library's prelude in that you'll
+//! almost always want to import its entire contents, but unlike the standard
+//! library's prelude you'll have to do so manually:
+//!
+//! ```
+//! use tokio::prelude::*;
+//! ```
+//!
+//! The prelude may grow over time as additional items see ubiquitous use.
+
+pub use tokio_io::{
+    AsyncRead,
+    AsyncWrite,
+};
+
+pub use util::{
+    FutureExt,
+    StreamExt,
+};
+
+pub use ::std::io::{
+    Read,
+    Write,
+};
+
+pub use futures::{
+    Future,
+    future,
+    Stream,
+    stream,
+    Sink,
+    IntoFuture,
+    Async,
+    AsyncSink,
+    Poll,
+    task,
+};
+
+#[cfg(feature = "async-await-preview")]
+#[doc(inline)]
+pub use tokio_async_await::{
+    io::{
+        AsyncReadExt,
+        AsyncWriteExt,
+    },
+    sink::{
+        SinkExt,
+    },
+    stream::{
+        StreamExt as StreamAsyncExt,
+    },
+};

src/runtime/builder.rs

@@ -3,10 +3,12 @@ use runtime::{Inner, Runtime};
 use reactor::Reactor;
 
 use std::io;
+use std::sync::Mutex;
+use std::time::Duration;
 
+use num_cpus;
 use tokio_reactor;
 use tokio_threadpool::Builder as ThreadPoolBuilder;
-use tokio_threadpool::park::DefaultPark;
 use tokio_timer::clock::{self, Clock};
 use tokio_timer::timer::{self, Timer};
 
@@ -26,30 +28,37 @@ use tokio_timer::timer::{self, Timer};
 /// # Examples
 ///
 /// ```
-/// # extern crate tokio;
-/// # extern crate tokio_threadpool;
-/// # use tokio::runtime::Builder;
+/// extern crate tokio;
+/// extern crate tokio_timer;
 ///
-/// # pub fn main() {
-/// // create and configure ThreadPool
-/// let mut threadpool_builder = tokio_threadpool::Builder::new();
-/// threadpool_builder
-///     .name_prefix("my-runtime-worker-")
-///     .pool_size(4);
+/// use std::time::Duration;
 ///
-/// // build Runtime
-/// let runtime = Builder::new()
-///     .threadpool_builder(threadpool_builder)
-///     .build();
-/// // ... call runtime.run(...)
-/// # let _ = runtime;
-/// # }
+/// use tokio::runtime::Builder;
+/// use tokio_timer::clock::Clock;
+///
+/// fn main() {
+///     // build Runtime
+///     let mut runtime = Builder::new()
+///         .blocking_threads(4)
+///         .clock(Clock::system())
+///         .core_threads(4)
+///         .keep_alive(Some(Duration::from_secs(60)))
+///         .name_prefix("my-custom-name-")
+///         .stack_size(3 * 1024 * 1024)
+///         .build()
+///         .unwrap();
+///
+///     // use runtime ...
+/// }
 /// ```
 #[derive(Debug)]
 pub struct Builder {
     /// Thread pool specific builder
     threadpool_builder: ThreadPoolBuilder,
 
+    /// The number of worker threads
+    core_threads: usize,
+
     /// The clock to use
     clock: Clock,
 }
@@ -60,11 +69,15 @@ impl Builder {
     ///
     /// Configuration methods can be chained on the return value.
     pub fn new() -> Builder {
+        let core_threads = num_cpus::get().max(1);
+
         let mut threadpool_builder = ThreadPoolBuilder::new();
         threadpool_builder.name_prefix("tokio-runtime-worker-");
+        threadpool_builder.pool_size(core_threads);
 
         Builder {
             threadpool_builder,
+            core_threads,
             clock: Clock::new(),
         }
     }
@@ -76,11 +89,210 @@ impl Builder {
     }
 
     /// Set builder to set up the thread pool instance.
+    #[deprecated(
+        since="0.1.9",
+        note="use the `core_threads`, `blocking_threads`, `name_prefix`, \
+              `keep_alive`, and `stack_size` functions on `runtime::Builder`, \
+              instead")]
+    #[doc(hidden)]
     pub fn threadpool_builder(&mut self, val: ThreadPoolBuilder) -> &mut Self {
         self.threadpool_builder = val;
         self
     }
 
+    /// Set the maximum number of worker threads for the `Runtime`'s thread pool.
+    ///
+    /// This must be a number between 1 and 32,768 though it is advised to keep
+    /// this value on the smaller side.
+    ///
+    /// The default value is the number of cores available to the system.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # extern crate futures;
+    /// # use tokio::runtime;
+    ///
+    /// # pub fn main() {
+    /// let mut rt = runtime::Builder::new()
+    ///     .core_threads(4)
+    ///     .build()
+    ///     .unwrap();
+    /// # }
+    /// ```
+    pub fn core_threads(&mut self, val: usize) -> &mut Self {
+        self.core_threads = val;
+        self.threadpool_builder.pool_size(val);
+        self
+    }
+
+    /// Set the maximum number of concurrent blocking sections in the `Runtime`'s
+    /// thread pool.
+    ///
+    /// When the maximum concurrent `blocking` calls is reached, any further
+    /// calls to `blocking` will return `NotReady` and the task is notified once
+    /// previously in-flight calls to `blocking` return.
+    ///
+    /// This must be a number between 1 and 32,768 though it is advised to keep
+    /// this value on the smaller side.
+    ///
+    /// The default value is 100.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # extern crate futures;
+    /// # use tokio::runtime;
+    ///
+    /// # pub fn main() {
+    /// let mut rt = runtime::Builder::new()
+    ///     .blocking_threads(200)
+    ///     .build();
+    /// # }
+    /// ```
+    pub fn blocking_threads(&mut self, val: usize) -> &mut Self {
+        self.threadpool_builder.max_blocking(val);
+        self
+    }
+
+    /// Set the worker thread keep alive duration for threads in the `Runtime`'s
+    /// thread pool.
+    ///
+    /// If set, a worker thread will wait for up to the specified duration for
+    /// work, at which point the thread will shutdown. When work becomes
+    /// available, a new thread will eventually be spawned to replace the one
+    /// that shut down.
+    ///
+    /// When the value is `None`, the thread will wait for work forever.
+    ///
+    /// The default value is `None`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # extern crate futures;
+    /// # use tokio::runtime;
+    /// use std::time::Duration;
+    ///
+    /// # pub fn main() {
+    /// let mut rt = runtime::Builder::new()
+    ///     .keep_alive(Some(Duration::from_secs(30)))
+    ///     .build();
+    /// # }
+    /// ```
+    pub fn keep_alive(&mut self, val: Option<Duration>) -> &mut Self {
+        self.threadpool_builder.keep_alive(val);
+        self
+    }
+
+    /// Set name prefix of threads spawned by the `Runtime`'s thread pool.
+    ///
+    /// Thread name prefix is used for generating thread names. For example, if
+    /// prefix is `my-pool-`, then threads in the pool will get names like
+    /// `my-pool-1` etc.
+    ///
+    /// The default prefix is "tokio-runtime-worker-".
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # extern crate futures;
+    /// # use tokio::runtime;
+    ///
+    /// # pub fn main() {
+    /// let mut rt = runtime::Builder::new()
+    ///     .name_prefix("my-pool-")
+    ///     .build();
+    /// # }
+    /// ```
+    pub fn name_prefix<S: Into<String>>(&mut self, val: S) -> &mut Self {
+        self.threadpool_builder.name_prefix(val);
+        self
+    }
+
+    /// Set the stack size (in bytes) for worker threads.
+    ///
+    /// The actual stack size may be greater than this value if the platform
+    /// specifies minimal stack size.
+    ///
+    /// The default stack size for spawned threads is 2 MiB, though this
+    /// particular stack size is subject to change in the future.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # extern crate futures;
+    /// # use tokio::runtime;
+    ///
+    /// # pub fn main() {
+    /// let mut rt = runtime::Builder::new()
+    ///     .stack_size(32 * 1024)
+    ///     .build();
+    /// # }
+    /// ```
+    pub fn stack_size(&mut self, val: usize) -> &mut Self {
+        self.threadpool_builder.stack_size(val);
+        self
+    }
+
+    /// Execute function `f` after each thread is started but before it starts
+    /// doing work.
+    ///
+    /// This is intended for bookkeeping and monitoring use cases.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # extern crate futures;
+    /// # use tokio::runtime;
+    ///
+    /// # pub fn main() {
+    /// let thread_pool = runtime::Builder::new()
+    ///     .after_start(|| {
+    ///         println!("thread started");
+    ///     })
+    ///     .build();
+    /// # }
+    /// ```
+    pub fn after_start<F>(&mut self, f: F) -> &mut Self
+        where F: Fn() + Send + Sync + 'static
+    {
+        self.threadpool_builder.after_start(f);
+        self
+    }
+
+    /// Execute function `f` before each thread stops.
+    ///
+    /// This is intended for bookkeeping and monitoring use cases.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # extern crate futures;
+    /// # use tokio::runtime;
+    ///
+    /// # pub fn main() {
+    /// let thread_pool = runtime::Builder::new()
+    ///     .before_stop(|| {
+    ///         println!("thread stopping");
+    ///     })
+    ///     .build();
+    /// # }
+    /// ```
+    pub fn before_stop<F>(&mut self, f: F) -> &mut Self
+        where F: Fn() + Send + Sync + 'static
+    {
+        self.threadpool_builder.before_stop(f);
+        self
+    }
+
     /// Create the configured `Runtime`.
     ///
     /// The returned `ThreadPool` instance is ready to spawn tasks.
@@ -97,50 +309,58 @@ impl Builder {
     /// # }
     /// ```
     pub fn build(&mut self) -> io::Result<Runtime> {
-        use std::collections::HashMap;
-        use std::sync::{Arc, Mutex};
+        // TODO(stjepang): Once we remove the `threadpool_builder` method, remove this line too.
+        self.threadpool_builder.pool_size(self.core_threads);
+
+        let mut reactor_handles = Vec::new();
+        let mut timer_handles = Vec::new();
+        let mut timers = Vec::new();
+
+        for _ in 0..self.core_threads {
+            // Create a new reactor.
+            let reactor = Reactor::new()?;
+            reactor_handles.push(reactor.handle());
+
+            // Create a new timer.
+            let timer = Timer::new_with_now(reactor, self.clock.clone());
+            timer_handles.push(timer.handle());
+            timers.push(Mutex::new(Some(timer)));
+        }
 
         // Get a handle to the clock for the runtime.
-        let clock1 = self.clock.clone();
-        let clock2 = clock1.clone();
-
-        let timers = Arc::new(Mutex::new(HashMap::<_, timer::Handle>::new()));
-        let t1 = timers.clone();
-
-        // Spawn a reactor on a background thread.
-        let reactor = Reactor::new()?.background()?;
-
-        // Get a handle to the reactor.
-        let reactor_handle = reactor.handle().clone();
+        let clock = self.clock.clone();
 
         let pool = self.threadpool_builder
             .around_worker(move |w, enter| {
-                let timer_handle = t1.lock().unwrap()
-                    .get(w.id()).unwrap()
-                    .clone();
+                let index = w.id().to_usize();
 
-                tokio_reactor::with_default(&reactor_handle, enter, |enter| {
-                    clock::with_default(&clock1, enter, |enter| {
-                        timer::with_default(&timer_handle, enter, |_| {
+                tokio_reactor::with_default(&reactor_handles[index], enter, |enter| {
+                    clock::with_default(&clock, enter, |enter| {
+                        timer::with_default(&timer_handles[index], enter, |_| {
                             w.run();
                         });
                     })
                 });
             })
             .custom_park(move |worker_id| {
-                // Create a new timer
-                let timer = Timer::new_with_now(DefaultPark::new(), clock2.clone());
+                let index = worker_id.to_usize();
 
-                timers.lock().unwrap()
-                    .insert(worker_id.clone(), timer.handle());
-
-                timer
+                timers[index]
+                    .lock()
+                    .unwrap()
+                    .take()
+                    .unwrap()
             })
             .build();
 
+        // To support deprecated `reactor()` function
+        let reactor = Reactor::new()?;
+        let reactor_handle = reactor.handle();
+
         Ok(Runtime {
             inner: Some(Inner {
-                reactor,
+                reactor_handle,
+                reactor: Mutex::new(Some(reactor)),
                 pool,
             }),
         })

src/runtime/current_thread/mod.rs

@@ -71,6 +71,8 @@ mod runtime;
 
 pub use self::builder::Builder;
 pub use self::runtime::{Runtime, Handle};
+pub use tokio_current_thread::spawn;
+pub use tokio_current_thread::TaskExecutor;
 
 use futures::Future;
 

src/runtime/current_thread/runtime.rs

@@ -7,7 +7,7 @@ use tokio_timer::clock::{self, Clock};
 use tokio_timer::timer::{self, Timer};
 use tokio_executor;
 
-use futures::Future;
+use futures::{future, Future};
 
 use std::fmt;
 use std::error::Error;
@@ -42,6 +42,38 @@ impl Handle {
     where F: Future<Item = (), Error = ()> + Send + 'static {
         self.0.spawn(future)
     }
+
+    /// Provides a best effort **hint** to whether or not `spawn` will succeed.
+    ///
+    /// This function may return both false positives **and** false negatives.
+    /// If `status` returns `Ok`, then a call to `spawn` will *probably*
+    /// succeed, but may fail. If `status` returns `Err`, a call to `spawn` will
+    /// *probably* fail, but may succeed.
+    ///
+    /// This allows a caller to avoid creating the task if the call to `spawn`
+    /// has a high likelihood of failing.
+    pub fn status(&self) -> Result<(), tokio_executor::SpawnError> {
+        self.0.status()
+    }
+}
+
+impl<T> future::Executor<T> for Handle
+where T: Future<Item = (), Error = ()> + Send + 'static,
+{
+    fn execute(&self, future: T) -> Result<(), future::ExecuteError<T>> {
+        if let Err(e) = self.status() {
+            let kind = if e.is_at_capacity() {
+                future::ExecuteErrorKind::NoCapacity
+            } else {
+                future::ExecuteErrorKind::Shutdown
+            };
+
+            return Err(future::ExecuteError::new(kind, future));
+        }
+
+        let _ = self.spawn(future);
+        Ok(())
+    }
 }
 
 /// Error returned by the `run` function.

src/runtime/mod.rs

@@ -121,10 +121,12 @@ pub use self::builder::Builder;
 pub use self::shutdown::Shutdown;
 pub use self::task_executor::TaskExecutor;
 
-use reactor::{Background, Handle};
+use reactor::{Handle, Reactor};
 
 use std::io;
+use std::sync::Mutex;
 
+use tokio_executor::enter;
 use tokio_threadpool as threadpool;
 
 use futures;
@@ -151,8 +153,11 @@ pub struct Runtime {
 
 #[derive(Debug)]
 struct Inner {
-    /// Reactor running on a background thread.
-    reactor: Background,
+    /// A handle to the reactor in the background thread.
+    reactor_handle: Handle,
+
+    // TODO: This should go away in 0.2
+    reactor: Mutex<Option<Reactor>>,
 
     /// Task execution pool.
     pool: threadpool::ThreadPool,
@@ -208,9 +213,13 @@ struct Inner {
 pub fn run<F>(future: F)
 where F: Future<Item = (), Error = ()> + Send + 'static,
 {
-    let mut runtime = Runtime::new().unwrap();
+    // Check enter before creating a new Runtime...
+    let mut entered = enter().expect("nested tokio::run");
+    let mut runtime = Runtime::new().expect("failed to start new Runtime");
     runtime.spawn(future);
-    runtime.shutdown_on_idle().wait().unwrap();
+    entered
+        .block_on(runtime.shutdown_on_idle())
+        .expect("shutdown cannot error")
 }
 
 impl Runtime {
@@ -251,6 +260,7 @@ impl Runtime {
     #[deprecated(since = "0.1.5", note = "use `reactor` instead")]
     #[doc(hidden)]
     pub fn handle(&self) -> &Handle {
+        #[allow(deprecated)]
         self.reactor()
     }
 
@@ -272,8 +282,16 @@ impl Runtime {
     ///
     /// // use `reactor_handle`
     /// ```
+    #[deprecated(since = "0.1.11", note = "there is now a reactor per worker thread")]
     pub fn reactor(&self) -> &Handle {
-        self.inner().reactor.handle()
+        let mut reactor = self.inner().reactor.lock().unwrap();
+        if let Some(reactor) = reactor.take() {
+            if let Ok(background) = reactor.background() {
+                background.forget();
+            }
+        }
+
+        &self.inner().reactor_handle
     }
 
     /// Return a handle to the runtime's executor.
@@ -345,7 +363,7 @@ impl Runtime {
     /// complete, and yielding its resolved result. Any tasks or timers which
     /// the future spawns internally will be executed on the runtime.
     ///
-    /// This method should not be called from an asynchrounous context.
+    /// This method should not be called from an asynchronous context.
     ///
     /// # Panics
     ///
@@ -357,9 +375,10 @@ impl Runtime {
         R: Send + 'static,
         E: Send + 'static,
     {
+        let mut entered = enter().expect("nested block_on");
         let (tx, rx) = futures::sync::oneshot::channel();
         self.spawn(future.then(move |r| tx.send(r).map_err(|_| unreachable!())));
-        rx.wait().unwrap()
+        entered.block_on(rx).unwrap()
     }
 
     /// Run a future to completion on the Tokio runtime, then wait for all
@@ -370,7 +389,7 @@ impl Runtime {
     /// its resolved result. Any tasks or timers which the future spawns
     /// internally will be executed on the runtime and waited for completion.
     ///
-    /// This method should not be called from an asynchrounous context.
+    /// This method should not be called from an asynchronous context.
     ///
     /// # Panics
     ///
@@ -382,9 +401,16 @@ impl Runtime {
         R: Send + 'static,
         E: Send + 'static,
     {
-        let res = self.block_on(future);
-        self.shutdown_on_idle().wait().unwrap();
-        res
+        let mut entered = enter().expect("nested block_on_all");
+        let (tx, rx) = futures::sync::oneshot::channel();
+        self.spawn(future.then(move |r| tx.send(r).map_err(|_| unreachable!())));
+        let block = rx
+            .map_err(|_| unreachable!())
+            .and_then(move |r| {
+                self.shutdown_on_idle()
+                    .map(move |()| r)
+            });
+        entered.block_on(block).unwrap()
     }
 
     /// Signals the runtime to shutdown once it becomes idle.
@@ -421,16 +447,7 @@ impl Runtime {
     /// [mod]: index.html
     pub fn shutdown_on_idle(mut self) -> Shutdown {
         let inner = self.inner.take().unwrap();
-
-        let inner = Box::new({
-            let pool = inner.pool;
-            let reactor = inner.reactor;
-
-            pool.shutdown_on_idle().and_then(|_| {
-                reactor.shutdown_on_idle()
-            })
-        });
-
+        let inner = inner.pool.shutdown_on_idle();
         Shutdown { inner }
     }
 

src/runtime/shutdown.rs

@@ -1,4 +1,5 @@
 use runtime::Inner;
+use tokio_threadpool as threadpool;
 
 use std::fmt;
 
@@ -6,23 +7,12 @@ use futures::{Future, Poll};
 
 /// A future that resolves when the Tokio `Runtime` is shut down.
 pub struct Shutdown {
-    pub(super) inner: Box<Future<Item = (), Error = ()> + Send>,
+    pub(super) inner: threadpool::Shutdown,
 }
 
 impl Shutdown {
     pub(super) fn shutdown_now(inner: Inner) -> Self {
-        let inner = Box::new({
-            let pool = inner.pool;
-            let reactor = inner.reactor;
-
-            pool.shutdown_now().and_then(|_| {
-                reactor.shutdown_now()
-                    .then(|_| {
-                        Ok(())
-                    })
-            })
-        });
-
+        let inner = inner.pool.shutdown_now();
         Shutdown { inner }
     }
 }

src/timer.rs

@@ -10,9 +10,9 @@
 //!   is initialized with a `Duration` and repeatedly yields each time the
 //!   duration elapses.
 //!
-//! * [`Timeout`][Timeeout]: Wraps a future or stream, setting an upper bound to the
+//! * [`Timeout`][Timeout]: Wraps a future or stream, setting an upper bound to the
 //!   amount of time it is allowed to execute. If the future or stream does not
-//!   completee in time, then it is canceled and an error is returned.
+//!   complete in time, then it is canceled and an error is returned.
 //!
 //! * [`DelayQueue`]: A queue where items are returned once the requested delay
 //!   has expired.

src/util/future.rs

@@ -31,6 +31,9 @@ pub trait FutureExt: Future {
     /// If the future completes before `timeout` then the future will resolve
     /// with that item. Otherwise the future will resolve to an error.
     ///
+    /// The future is guaranteed to be polled at least once, even if `timeout`
+    /// is set to zero.
+    ///
     /// # Examples
     ///
     /// ```
@@ -69,3 +72,16 @@ pub trait FutureExt: Future {
 }
 
 impl<T: ?Sized> FutureExt for T where T: Future {}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use prelude::future;
+
+    #[test]
+    fn timeout_polls_at_least_once() {
+        let base_future = future::result::<(), ()>(Ok(()));
+        let timeouted_future = base_future.timeout(Duration::new(0, 0));
+        assert!(timeouted_future.wait().is_ok());
+    }
+}

src/util/mod.rs

@@ -1,10 +1,14 @@
 //! Utilities for working with Tokio.
 //!
 //! This module contains utilities that are useful for working with Tokio.
-//! Currently, this only includes [`FutureExt`], but this may grow over time.
+//! Currently, this only includes [`FutureExt`] and [`StreamExt`], but this
+//! may grow over time.
 //!
 //! [`FutureExt`]: trait.FutureExt.html
+//! [`StreamExt`]: trait.StreamExt.html
 
 mod future;
+mod stream;
 
 pub use self::future::FutureExt;
+pub use self::stream::StreamExt;

src/util/stream.rs

@@ -0,0 +1,73 @@
+use tokio_timer::{
+    throttle::Throttle,
+    Timeout,
+};
+
+use futures::Stream;
+
+use std::time::Duration;
+
+
+/// An extension trait for `Stream` that provides a variety of convenient
+/// combinator functions.
+///
+/// Currently, there only is a [`timeout`] function, but this will increase
+/// over time.
+///
+/// Users are not expected to implement this trait. All types that implement
+/// `Stream` already implement `StreamExt`.
+///
+/// This trait can be imported directly or via the Tokio prelude: `use
+/// tokio::prelude::*`.
+///
+/// [`timeout`]: #method.timeout
+pub trait StreamExt: Stream {
+    /// Throttle down the stream by enforcing a fixed delay between items.
+    ///
+    /// Errors are also delayed.
+    fn throttle(self, duration: Duration) -> Throttle<Self>
+    where Self: Sized
+    {
+        Throttle::new(self, duration)
+    }
+
+    /// Creates a new stream which allows `self` until `timeout`.
+    ///
+    /// This combinator creates a new stream which wraps the receiving stream
+    /// with a timeout. For each item, the returned stream is allowed to execute
+    /// until it completes or `timeout` has elapsed, whichever happens first.
+    ///
+    /// If an item completes before `timeout` then the stream will yield
+    /// with that item. Otherwise the stream will yield to an error.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate tokio;
+    /// # extern crate futures;
+    /// use tokio::prelude::*;
+    /// use std::time::Duration;
+    /// # use futures::future::{self, FutureResult};
+    ///
+    /// # fn long_future() -> FutureResult<(), ()> {
+    /// #   future::ok(())
+    /// # }
+    /// #
+    /// # fn main() {
+    /// let stream = long_future()
+    ///     .into_stream()
+    ///     .timeout(Duration::from_secs(1))
+    ///     .for_each(|i| future::ok(println!("item = {:?}", i)))
+    ///     .map_err(|e| println!("error = {:?}", e));
+    ///
+    /// tokio::run(stream);
+    /// # }
+    /// ```
+    fn timeout(self, timeout: Duration) -> Timeout<Self>
+    where Self: Sized,
+    {
+        Timeout::new(self, timeout)
+    }
+}
+
+impl<T: ?Sized> StreamExt for T where T: Stream {}

tests/length_delimited.rs

@@ -0,0 +1,580 @@
+extern crate tokio;
+extern crate futures;
+extern crate bytes;
+
+use tokio::io::{AsyncRead, AsyncWrite};
+use tokio::codec::*;
+
+use bytes::{Bytes, BytesMut, BufMut};
+use futures::{Stream, Sink, Poll};
+use futures::Async::*;
+
+use std::io;
+use std::collections::VecDeque;
+
+macro_rules! mock {
+    ($($x:expr,)*) => {{
+        let mut v = VecDeque::new();
+        v.extend(vec![$($x),*]);
+        Mock { calls: v }
+    }};
+}
+
+
+#[test]
+fn read_empty_io_yields_nothing() {
+    let mut io = FramedRead::new(mock!(), LengthDelimitedCodec::new());
+
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_single_frame_one_packet() {
+    let mut io = FramedRead::new(mock! {
+        Ok(b"\x00\x00\x00\x09abcdefghi"[..].into()),
+    }, LengthDelimitedCodec::new());
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_single_frame_one_packet_little_endian() {
+    let mut io = length_delimited::Builder::new()
+        .little_endian()
+        .new_read(mock! {
+            Ok(b"\x09\x00\x00\x00abcdefghi"[..].into()),
+        });
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_single_frame_one_packet_native_endian() {
+    let data = if cfg!(target_endian = "big") {
+        b"\x00\x00\x00\x09abcdefghi"
+    } else {
+        b"\x09\x00\x00\x00abcdefghi"
+    };
+    let mut io = length_delimited::Builder::new()
+        .native_endian()
+        .new_read(mock! {
+            Ok(data[..].into()),
+        });
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_single_multi_frame_one_packet() {
+    let mut data: Vec<u8> = vec![];
+    data.extend_from_slice(b"\x00\x00\x00\x09abcdefghi");
+    data.extend_from_slice(b"\x00\x00\x00\x03123");
+    data.extend_from_slice(b"\x00\x00\x00\x0bhello world");
+
+    let mut io = FramedRead::new(mock! {
+        Ok(data.into()),
+    }, LengthDelimitedCodec::new());
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"123"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"hello world"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_single_frame_multi_packet() {
+    let mut io = FramedRead::new(mock! {
+        Ok(b"\x00\x00"[..].into()),
+        Ok(b"\x00\x09abc"[..].into()),
+        Ok(b"defghi"[..].into()),
+    }, LengthDelimitedCodec::new());
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_multi_frame_multi_packet() {
+    let mut io = FramedRead::new(mock! {
+        Ok(b"\x00\x00"[..].into()),
+        Ok(b"\x00\x09abc"[..].into()),
+        Ok(b"defghi"[..].into()),
+        Ok(b"\x00\x00\x00\x0312"[..].into()),
+        Ok(b"3\x00\x00\x00\x0bhello world"[..].into()),
+    }, LengthDelimitedCodec::new());
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"123"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"hello world"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_single_frame_multi_packet_wait() {
+    let mut io = FramedRead::new(mock! {
+        Ok(b"\x00\x00"[..].into()),
+        Err(would_block()),
+        Ok(b"\x00\x09abc"[..].into()),
+        Err(would_block()),
+        Ok(b"defghi"[..].into()),
+        Err(would_block()),
+    }, LengthDelimitedCodec::new());
+
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_multi_frame_multi_packet_wait() {
+    let mut io = FramedRead::new(mock! {
+        Ok(b"\x00\x00"[..].into()),
+        Err(would_block()),
+        Ok(b"\x00\x09abc"[..].into()),
+        Err(would_block()),
+        Ok(b"defghi"[..].into()),
+        Err(would_block()),
+        Ok(b"\x00\x00\x00\x0312"[..].into()),
+        Err(would_block()),
+        Ok(b"3\x00\x00\x00\x0bhello world"[..].into()),
+        Err(would_block()),
+    }, LengthDelimitedCodec::new());
+
+
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"123"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"hello world"[..].into())));
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_incomplete_head() {
+    let mut io = FramedRead::new(mock! {
+        Ok(b"\x00\x00"[..].into()),
+    }, LengthDelimitedCodec::new());
+
+    assert!(io.poll().is_err());
+}
+
+#[test]
+fn read_incomplete_head_multi() {
+    let mut io = FramedRead::new(mock! {
+        Err(would_block()),
+        Ok(b"\x00"[..].into()),
+        Err(would_block()),
+    }, LengthDelimitedCodec::new());
+
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert!(io.poll().is_err());
+}
+
+#[test]
+fn read_incomplete_payload() {
+    let mut io = FramedRead::new(mock! {
+        Ok(b"\x00\x00\x00\x09ab"[..].into()),
+        Err(would_block()),
+        Ok(b"cd"[..].into()),
+        Err(would_block()),
+    }, LengthDelimitedCodec::new());
+
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert_eq!(io.poll().unwrap(), NotReady);
+    assert!(io.poll().is_err());
+}
+
+#[test]
+fn read_max_frame_len() {
+    let mut io = length_delimited::Builder::new()
+        .max_frame_length(5)
+        .new_read(mock! {
+            Ok(b"\x00\x00\x00\x09abcdefghi"[..].into()),
+        });
+
+    assert_eq!(io.poll().unwrap_err().kind(), io::ErrorKind::InvalidData);
+}
+
+#[test]
+fn read_update_max_frame_len_at_rest() {
+    let mut io = length_delimited::Builder::new()
+        .new_read(mock! {
+            Ok(b"\x00\x00\x00\x09abcdefghi"[..].into()),
+            Ok(b"\x00\x00\x00\x09abcdefghi"[..].into()),
+        });
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    io.decoder_mut().set_max_frame_length(5);
+    assert_eq!(io.poll().unwrap_err().kind(), io::ErrorKind::InvalidData);
+}
+
+#[test]
+fn read_update_max_frame_len_in_flight() {
+    let mut io = length_delimited::Builder::new()
+        .new_read(mock! {
+            Ok(b"\x00\x00\x00\x09abcd"[..].into()),
+            Err(would_block()),
+            Ok(b"efghi"[..].into()),
+            Ok(b"\x00\x00\x00\x09abcdefghi"[..].into()),
+        });
+
+    assert_eq!(io.poll().unwrap(), NotReady);
+    io.decoder_mut().set_max_frame_length(5);
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap_err().kind(), io::ErrorKind::InvalidData);
+}
+
+#[test]
+fn read_one_byte_length_field() {
+    let mut io = length_delimited::Builder::new()
+        .length_field_length(1)
+        .new_read(mock! {
+            Ok(b"\x09abcdefghi"[..].into()),
+        });
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_header_offset() {
+    let mut io = length_delimited::Builder::new()
+        .length_field_length(2)
+        .length_field_offset(4)
+        .new_read(mock! {
+            Ok(b"zzzz\x00\x09abcdefghi"[..].into()),
+        });
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_single_multi_frame_one_packet_skip_none_adjusted() {
+    let mut data: Vec<u8> = vec![];
+    data.extend_from_slice(b"xx\x00\x09abcdefghi");
+    data.extend_from_slice(b"yy\x00\x03123");
+    data.extend_from_slice(b"zz\x00\x0bhello world");
+
+    let mut io = length_delimited::Builder::new()
+        .length_field_length(2)
+        .length_field_offset(2)
+        .num_skip(0)
+        .length_adjustment(4)
+        .new_read(mock! {
+            Ok(data.into()),
+        });
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"xx\x00\x09abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"yy\x00\x03123"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"zz\x00\x0bhello world"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn read_single_multi_frame_one_packet_length_includes_head() {
+    let mut data: Vec<u8> = vec![];
+    data.extend_from_slice(b"\x00\x0babcdefghi");
+    data.extend_from_slice(b"\x00\x05123");
+    data.extend_from_slice(b"\x00\x0dhello world");
+
+    let mut io = length_delimited::Builder::new()
+        .length_field_length(2)
+        .length_adjustment(-2)
+        .new_read(mock! {
+            Ok(data.into()),
+        });
+
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"abcdefghi"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"123"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(Some(b"hello world"[..].into())));
+    assert_eq!(io.poll().unwrap(), Ready(None));
+}
+
+#[test]
+fn write_single_frame_length_adjusted() {
+    let mut io = length_delimited::Builder::new()
+        .length_adjustment(-2)
+        .new_write(mock! {
+            Ok(b"\x00\x00\x00\x0b"[..].into()),
+            Ok(b"abcdefghi"[..].into()),
+            Ok(Flush),
+        });
+    assert!(io.start_send(Bytes::from("abcdefghi")).unwrap().is_ready());
+    assert!(io.poll_complete().unwrap().is_ready());
+    assert!(io.get_ref().calls.is_empty());
+}
+
+#[test]
+fn write_nothing_yields_nothing() {
+    let mut io = FramedWrite::new(
+        mock!(),
+        LengthDelimitedCodec::new()
+    );
+    assert!(io.poll_complete().unwrap().is_ready());
+}
+
+#[test]
+fn write_single_frame_one_packet() {
+    let mut io = FramedWrite::new(mock! {
+        Ok(b"\x00\x00\x00\x09"[..].into()),
+        Ok(b"abcdefghi"[..].into()),
+        Ok(Flush),
+    }, LengthDelimitedCodec::new());
+
+    assert!(io.start_send(Bytes::from("abcdefghi")).unwrap().is_ready());
+    assert!(io.poll_complete().unwrap().is_ready());
+    assert!(io.get_ref().calls.is_empty());
+}
+
+#[test]
+fn write_single_multi_frame_one_packet() {
+    let mut io = FramedWrite::new(mock! {
+        Ok(b"\x00\x00\x00\x09"[..].into()),
+        Ok(b"abcdefghi"[..].into()),
+        Ok(b"\x00\x00\x00\x03"[..].into()),
+        Ok(b"123"[..].into()),
+        Ok(b"\x00\x00\x00\x0b"[..].into()),
+        Ok(b"hello world"[..].into()),
+        Ok(Flush),
+    }, LengthDelimitedCodec::new());
+
+    assert!(io.start_send(Bytes::from("abcdefghi")).unwrap().is_ready());
+    assert!(io.start_send(Bytes::from("123")).unwrap().is_ready());
+    assert!(io.start_send(Bytes::from("hello world")).unwrap().is_ready());
+    assert!(io.poll_complete().unwrap().is_ready());
+    assert!(io.get_ref().calls.is_empty());
+}
+
+#[test]
+fn write_single_multi_frame_multi_packet() {
+    let mut io = FramedWrite::new(mock! {
+        Ok(b"\x00\x00\x00\x09"[..].into()),
+        Ok(b"abcdefghi"[..].into()),
+        Ok(Flush),
+        Ok(b"\x00\x00\x00\x03"[..].into()),
+        Ok(b"123"[..].into()),
+        Ok(Flush),
+        Ok(b"\x00\x00\x00\x0b"[..].into()),
+        Ok(b"hello world"[..].into()),
+        Ok(Flush),
+    }, LengthDelimitedCodec::new());
+
+    assert!(io.start_send(Bytes::from("abcdefghi")).unwrap().is_ready());
+    assert!(io.poll_complete().unwrap().is_ready());
+    assert!(io.start_send(Bytes::from("123")).unwrap().is_ready());
+    assert!(io.poll_complete().unwrap().is_ready());
+    assert!(io.start_send(Bytes::from("hello world")).unwrap().is_ready());
+    assert!(io.poll_complete().unwrap().is_ready());
+    assert!(io.get_ref().calls.is_empty());
+}
+
+#[test]
+fn write_single_frame_would_block() {
+    let mut io = FramedWrite::new(mock! {
+        Err(would_block()),
+        Ok(b"\x00\x00"[..].into()),
+        Err(would_block()),
+        Ok(b"\x00\x09"[..].into()),
+        Ok(b"abcdefghi"[..].into()),
+        Ok(Flush),
+    }, LengthDelimitedCodec::new());
+
+    assert!(io.start_send(Bytes::from("abcdefghi")).unwrap().is_ready());
+    assert!(!io.poll_complete().unwrap().is_ready());
+    assert!(!io.poll_complete().unwrap().is_ready());
+    assert!(io.poll_complete().unwrap().is_ready());
+
+    assert!(io.get_ref().calls.is_empty());
+}
+
+#[test]
+fn write_single_frame_little_endian() {
+    let mut io = length_delimited::Builder::new()
+        .little_endian()
+        .new_write(mock! {
+            Ok(b"\x09\x00\x00\x00"[..].into()),
+            Ok(b"abcdefghi"[..].into()),
+            Ok(Flush),
+        });
+
+    assert!(io.start_send(Bytes::from("abcdefghi")).unwrap().is_ready());
+    assert!(io.poll_complete().unwrap().is_ready());
+    assert!(io.get_ref().calls.is_empty());
+}
+
+
+#[test]
+fn write_single_frame_with_short_length_field() {
+    let mut io = length_delimited::Builder::new()
+        .length_field_length(1)
+        .new_write(mock! {
+            Ok(b"\x09"[..].into()),
+            Ok(b"abcdefghi"[..].into()),
+            Ok(Flush),
+        });
+
+    assert!(io.start_send(Bytes::from("abcdefghi")).unwrap().is_ready());
+    assert!(io.poll_complete().unwrap().is_ready());
+    assert!(io.get_ref().calls.is_empty());
+}
+
+#[test]
+fn write_max_frame_len() {
+    let mut io = length_delimited::Builder::new()
+        .max_frame_length(5)
+        .new_write(mock! { });
+
+    assert_eq!(io.start_send(Bytes::from("abcdef")).unwrap_err().kind(), io::ErrorKind::InvalidInput);
+    assert!(io.get_ref().calls.is_empty());
+}
+
+#[test]
+fn write_update_max_frame_len_at_rest() {
+    let mut io = length_delimited::Builder::new()
+        .new_write(mock! {
+            Ok(b"\x00\x00\x00\x06"[..].into()),
+            Ok(b"abcdef"[..].into()),
+            Ok(Flush),
+        });
+
+    assert!(io.start_send(Bytes::from("abcdef")).unwrap().is_ready());
+    assert!(io.poll_complete().unwrap().is_ready());
+    io.encoder_mut().set_max_frame_length(5);
+    assert_eq!(io.start_send(Bytes::from("abcdef")).unwrap_err().kind(), io::ErrorKind::InvalidInput);
+    assert!(io.get_ref().calls.is_empty());
+}
+
+#[test]
+fn write_update_max_frame_len_in_flight() {
+    let mut io = length_delimited::Builder::new()
+        .new_write(mock! {
+            Ok(b"\x00\x00\x00\x06"[..].into()),
+            Ok(b"ab"[..].into()),
+            Err(would_block()),
+            Ok(b"cdef"[..].into()),
+            Ok(Flush),
+        });
+
+    assert!(io.start_send(Bytes::from("abcdef")).unwrap().is_ready());
+    assert!(!io.poll_complete().unwrap().is_ready());
+    io.encoder_mut().set_max_frame_length(5);
+    assert!(io.poll_complete().unwrap().is_ready());
+    assert_eq!(io.start_send(Bytes::from("abcdef")).unwrap_err().kind(), io::ErrorKind::InvalidInput);
+    assert!(io.get_ref().calls.is_empty());
+}
+
+#[test]
+fn write_zero() {
+    let mut io = length_delimited::Builder::new()
+        .new_write(mock! { });
+
+    assert!(io.start_send(Bytes::from("abcdef")).unwrap().is_ready());
+    assert_eq!(io.poll_complete().unwrap_err().kind(), io::ErrorKind::WriteZero);
+    assert!(io.get_ref().calls.is_empty());
+}
+
+#[test]
+fn encode_overflow() {
+    // Test reproducing tokio-rs/tokio#681.
+    let mut codec = length_delimited::Builder::new().new_codec();
+    let mut buf = BytesMut::with_capacity(1024);
+
+    // Put some data into the buffer without resizing it to hold more.
+    let some_as = std::iter::repeat(b'a')
+        .take(1024)
+        .collect::<Vec<_>>();
+    buf.put_slice(&some_as[..]);
+
+    // Trying to encode the length header should resize the buffer if it won't fit.
+    codec.encode(Bytes::from("hello"), &mut buf).unwrap();
+}
+
+// ===== Test utils =====
+
+fn would_block() -> io::Error {
+    io::Error::new(io::ErrorKind::WouldBlock, "would block")
+}
+
+struct Mock {
+    calls: VecDeque<io::Result<Op>>,
+}
+
+enum Op {
+    Data(Vec<u8>),
+    Flush,
+}
+
+use self::Op::*;
+
+impl io::Read for Mock {
+    fn read(&mut self, dst: &mut [u8]) -> io::Result<usize> {
+        match self.calls.pop_front() {
+            Some(Ok(Op::Data(data))) => {
+                debug_assert!(dst.len() >= data.len());
+                dst[..data.len()].copy_from_slice(&data[..]);
+                Ok(data.len())
+            }
+            Some(Ok(_)) => panic!(),
+            Some(Err(e)) => Err(e),
+            None => Ok(0),
+        }
+    }
+}
+
+impl AsyncRead for Mock {
+}
+
+impl io::Write for Mock {
+    fn write(&mut self, src: &[u8]) -> io::Result<usize> {
+        match self.calls.pop_front() {
+            Some(Ok(Op::Data(data))) => {
+                let len = data.len();
+                assert!(src.len() >= len, "expect={:?}; actual={:?}", data, src);
+                assert_eq!(&data[..], &src[..len]);
+                Ok(len)
+            }
+            Some(Ok(_)) => panic!(),
+            Some(Err(e)) => Err(e),
+            None => Ok(0),
+        }
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        match self.calls.pop_front() {
+            Some(Ok(Op::Flush)) => {
+                Ok(())
+            }
+            Some(Ok(_)) => panic!(),
+            Some(Err(e)) => Err(e),
+            None => Ok(()),
+        }
+    }
+}
+
+impl AsyncWrite for Mock {
+    fn shutdown(&mut self) -> Poll<(), io::Error> {
+        Ok(Ready(()))
+    }
+}
+
+impl<'a> From<&'a [u8]> for Op {
+    fn from(src: &'a [u8]) -> Op {
+        Op::Data(src.into())
+    }
+}
+
+impl From<Vec<u8>> for Op {
+    fn from(src: Vec<u8>) -> Op {
+        Op::Data(src)
+    }
+}

tests/runtime.rs

@@ -3,7 +3,7 @@ extern crate env_logger;
 extern crate futures;
 
 use futures::sync::oneshot;
-use std::sync::{Arc, Mutex};
+use std::sync::{Arc, Mutex, atomic};
 use std::thread;
 use tokio::io;
 use tokio::net::{TcpStream, TcpListener};
@@ -11,6 +11,11 @@ use tokio::prelude::future::lazy;
 use tokio::prelude::*;
 use tokio::runtime::Runtime;
 
+// this import is used in all child modules that have it in scope
+// from importing super::*, but the compiler doesn't realise that
+// and warns about it.
+pub use futures::future::Executor;
+
 macro_rules! t {
     ($e:expr) => (match $e {
         Ok(e) => e,
@@ -72,78 +77,130 @@ fn runtime_single_threaded_block_on() {
     tokio::runtime::current_thread::block_on_all(create_client_server_future()).unwrap();
 }
 
-#[test]
-fn runtime_single_threaded_block_on_all() {
-    let cnt = Arc::new(Mutex::new(0));
-    let c = cnt.clone();
+mod runtime_single_threaded_block_on_all {
+    use super::*;
 
-    let msg = tokio::runtime::current_thread::block_on_all(lazy(move || {
-        {
-            let mut x = c.lock().unwrap();
-            *x = 1 + *x;
-        }
+    fn test<F>(spawn: F)
+    where
+        F: Fn(Box<Future<Item=(), Error=()> + Send>),
+    {
+        let cnt = Arc::new(Mutex::new(0));
+        let c = cnt.clone();
 
-        // Spawn!
-        tokio::spawn(lazy(move || {
+        let msg = tokio::runtime::current_thread::block_on_all(lazy(move || {
             {
                 let mut x = c.lock().unwrap();
                 *x = 1 + *x;
             }
-            Ok::<(), ()>(())
-        }));
 
-        Ok::<_, ()>("hello")
-    })).unwrap();
+            // Spawn!
+            spawn(Box::new(lazy(move || {
+                {
+                    let mut x = c.lock().unwrap();
+                    *x = 1 + *x;
+                }
+                Ok::<(), ()>(())
+            })));
 
-    assert_eq!(2, *cnt.lock().unwrap());
-    assert_eq!(msg, "hello");
+            Ok::<_, ()>("hello")
+        })).unwrap();
+
+        assert_eq!(2, *cnt.lock().unwrap());
+        assert_eq!(msg, "hello");
+    }
+
+    #[test]
+    fn spawn() {
+       test(|f| { tokio::spawn(f); })
+    }
+
+    #[test]
+    fn execute() {
+        test(|f| {
+            tokio::executor::DefaultExecutor::current()
+                .execute(f)
+                .unwrap();
+        })
+    }
 }
 
-#[test]
-fn runtime_single_threaded_racy_spawn() {
-    let (trigger, exit) = futures::sync::oneshot::channel();
-    let (handle_tx, handle_rx) = ::std::sync::mpsc::channel();
-    let jh = ::std::thread::spawn(move || {
-        let mut rt = tokio::runtime::current_thread::Runtime::new().unwrap();
-        handle_tx.send(rt.handle()).unwrap();
+mod runtime_single_threaded_racy {
+    use super::*;
+    fn test<F>(spawn: F)
+    where
+        F: Fn(
+            tokio::runtime::current_thread::Handle,
+            Box<Future<Item=(), Error=()> + Send>,
+        ),
+    {
+        let (trigger, exit) = futures::sync::oneshot::channel();
+        let (handle_tx, handle_rx) = ::std::sync::mpsc::channel();
+        let jh = ::std::thread::spawn(move || {
+            let mut rt = tokio::runtime::current_thread::Runtime::new().unwrap();
+            handle_tx.send(rt.handle()).unwrap();
 
-        // don't exit until we are told to
-        rt.block_on(exit.map_err(|_| ())).unwrap();
+            // don't exit until we are told to
+            rt.block_on(exit.map_err(|_| ())).unwrap();
 
-        // run until all spawned futures (incl. the "exit" signal future) have completed.
-        rt.run().unwrap();
-    });
+            // run until all spawned futures (incl. the "exit" signal future) have completed.
+            rt.run().unwrap();
+        });
 
-    let (tx, rx) = futures::sync::oneshot::channel();
+        let (tx, rx) = futures::sync::oneshot::channel();
 
-    let handle = handle_rx.recv().unwrap();
-    handle
-        .spawn(futures::future::lazy(move || {
+        let handle = handle_rx.recv().unwrap();
+        spawn(handle, Box::new(futures::future::lazy(move || {
             tx.send(()).unwrap();
             Ok(())
-        }))
-        .unwrap();
+        })));
 
-    // signal runtime thread to exit
-    trigger.send(()).unwrap();
+        // signal runtime thread to exit
+        trigger.send(()).unwrap();
 
-    // wait for runtime thread to exit
-    jh.join().unwrap();
+        // wait for runtime thread to exit
+        jh.join().unwrap();
 
-    assert_eq!(rx.wait().unwrap(), ());
+        assert_eq!(rx.wait().unwrap(), ());
+    }
+
+    #[test]
+    fn spawn() {
+        test(|handle, f| { handle.spawn(f).unwrap(); })
+    }
+
+    #[test]
+    fn execute() {
+        test(|handle, f| { handle.execute(f).unwrap(); })
+    }
 }
 
-#[test]
-fn runtime_multi_threaded() {
-    let _ = env_logger::try_init();
+mod runtime_multi_threaded {
+    use super::*;
+    fn test<F>(spawn: F)
+    where
+        F: Fn(&mut Runtime) + Send + 'static,
+    {
+        let _ = env_logger::try_init();
 
-    let mut runtime = tokio::runtime::Builder::new()
-        .build()
-        .unwrap();
-    runtime.spawn(create_client_server_future());
-    runtime.shutdown_on_idle().wait().unwrap();
+        let mut runtime = tokio::runtime::Builder::new()
+            .build()
+            .unwrap();
+        spawn(&mut runtime);
+        runtime.shutdown_on_idle().wait().unwrap();
+    }
+
+    #[test]
+    fn spawn() {
+        test(|rt| { rt.spawn(create_client_server_future()); });
+    }
+
+    #[test]
+    fn execute() {
+        test(|rt| { rt.executor().execute(create_client_server_future()).unwrap(); });
+    }
 }
 
+
 #[test]
 fn block_on_timer() {
     use std::time::{Duration, Instant};
@@ -161,35 +218,57 @@ fn block_on_timer() {
     runtime.shutdown_on_idle().wait().unwrap();
 }
 
-#[test]
-fn spawn_from_block_on() {
-    let cnt = Arc::new(Mutex::new(0));
-    let c = cnt.clone();
+mod from_block_on {
+    use super::*;
 
-    let mut runtime = Runtime::new().unwrap();
-    let msg = runtime
-        .block_on(lazy(move || {
-            {
-                let mut x = c.lock().unwrap();
-                *x = 1 + *x;
-            }
+    fn test<F>(spawn: F)
+    where
+        F: Fn(Box<Future<Item=(), Error=()> + Send>) + Send + 'static,
+    {
+        let cnt = Arc::new(Mutex::new(0));
+        let c = cnt.clone();
 
-            // Spawn!
-            tokio::spawn(lazy(move || {
+        let mut runtime = Runtime::new().unwrap();
+        let msg = runtime
+            .block_on(lazy(move || {
                 {
                     let mut x = c.lock().unwrap();
                     *x = 1 + *x;
                 }
-                Ok::<(), ()>(())
-            }));
 
-            Ok::<_, ()>("hello")
-        }))
-        .unwrap();
+                // Spawn!
+                spawn(Box::new(lazy(move || {
+                    {
+                        let mut x = c.lock().unwrap();
+                        *x = 1 + *x;
+                    }
+                    Ok::<(), ()>(())
+                })));
 
-    runtime.shutdown_on_idle().wait().unwrap();
-    assert_eq!(2, *cnt.lock().unwrap());
-    assert_eq!(msg, "hello");
+                Ok::<_, ()>("hello")
+            }))
+            .unwrap();
+
+        runtime.shutdown_on_idle().wait().unwrap();
+        assert_eq!(2, *cnt.lock().unwrap());
+        assert_eq!(msg, "hello");
+    }
+
+    #[test]
+    fn execute() {
+        test(|f| {
+            tokio::executor::DefaultExecutor::current()
+                .execute(f)
+                .unwrap();
+        })
+    }
+
+    #[test]
+    fn spawn() {
+        test(|f| {
+            tokio::spawn(f);
+        })
+    }
 }
 
 #[test]
@@ -220,54 +299,218 @@ fn block_waits() {
     runtime.shutdown_on_idle().wait().unwrap();
 }
 
-#[test]
-fn spawn_many() {
+mod many {
+    use super::*;
+
     const ITER: usize = 200;
+    fn test<F>(spawn: F)
+    where
+        F: Fn(&mut Runtime, Box<Future<Item=(), Error=()> + Send>),
+    {
+        let cnt = Arc::new(Mutex::new(0));
+        let mut runtime = Runtime::new().unwrap();
 
-    let cnt = Arc::new(Mutex::new(0));
-    let mut runtime = Runtime::new().unwrap();
-
-    for _ in 0..ITER {
-        let c = cnt.clone();
-        runtime.spawn(lazy(move || {
-            {
-                let mut x = c.lock().unwrap();
-                *x = 1 + *x;
-            }
-            Ok::<(), ()>(())
-        }));
-    }
-
-    runtime.shutdown_on_idle().wait().unwrap();
-    assert_eq!(ITER, *cnt.lock().unwrap());
-}
-
-#[test]
-fn spawn_from_block_on_all() {
-    let cnt = Arc::new(Mutex::new(0));
-    let c = cnt.clone();
-
-    let runtime = Runtime::new().unwrap();
-    let msg = runtime
-        .block_on_all(lazy(move || {
-            {
-                let mut x = c.lock().unwrap();
-                *x = 1 + *x;
-            }
-
-            // Spawn!
-            tokio::spawn(lazy(move || {
+        for _ in 0..ITER {
+            let c = cnt.clone();
+            spawn(&mut runtime, Box::new(lazy(move || {
                 {
                     let mut x = c.lock().unwrap();
                     *x = 1 + *x;
                 }
                 Ok::<(), ()>(())
-            }));
+            })));
+        }
 
-            Ok::<_, ()>("hello")
-        }))
-        .unwrap();
+        runtime.shutdown_on_idle().wait().unwrap();
+        assert_eq!(ITER, *cnt.lock().unwrap());
+    }
 
-    assert_eq!(2, *cnt.lock().unwrap());
-    assert_eq!(msg, "hello");
+    #[test]
+    fn spawn() {
+        test(|rt, f| { rt.spawn(f); })
+    }
+
+    #[test]
+    fn execute() {
+        test(|rt, f| {
+            rt.executor()
+                .execute(f)
+                .unwrap();
+        })
+    }
+}
+
+
+mod from_block_on_all {
+    use super::*;
+
+    fn test<F>(spawn: F)
+    where
+        F: Fn(Box<Future<Item=(), Error=()> + Send>) + Send + 'static,
+    {
+        let cnt = Arc::new(Mutex::new(0));
+        let c = cnt.clone();
+
+        let runtime = Runtime::new().unwrap();
+        let msg = runtime
+            .block_on_all(lazy(move || {
+                {
+                    let mut x = c.lock().unwrap();
+                    *x = 1 + *x;
+                }
+
+                // Spawn!
+                spawn(Box::new(lazy(move || {
+                    {
+                        let mut x = c.lock().unwrap();
+                        *x = 1 + *x;
+                    }
+                    Ok::<(), ()>(())
+                })));
+
+                Ok::<_, ()>("hello")
+            }))
+            .unwrap();
+
+        assert_eq!(2, *cnt.lock().unwrap());
+        assert_eq!(msg, "hello");
+    }
+
+    #[test]
+    fn execute() {
+        test(|f| {
+            tokio::executor::DefaultExecutor::current()
+                .execute(f)
+                .unwrap();
+        })
+    }
+
+    #[test]
+    fn spawn() {
+        test(|f| { tokio::spawn(f); })
+    }
+}
+
+mod nested_enter {
+    use super::*;
+    use tokio::runtime::current_thread;
+    use std::panic;
+
+    fn test<F1, F2>(first: F1, nested: F2)
+    where
+        F1: Fn(Box<Future<Item=(), Error=()> + Send>) + Send + 'static,
+        F2: Fn(Box<Future<Item=(), Error=()> + Send>) + panic::UnwindSafe + Send + 'static,
+    {
+        let panicked = Arc::new(Mutex::new(false));
+        let panicked2 = panicked.clone();
+
+        // Since this is testing panics in other threads, printing about panics
+        // is noisy and can give the impression that the test is ignoring panics.
+        //
+        // It *is* ignoring them, but on purpose.
+        let prev_hook = panic::take_hook();
+        panic::set_hook(Box::new(|info| {
+            let s = info.to_string();
+            if s.starts_with("panicked at 'nested ")
+                || s.starts_with("panicked at 'Multiple executors at once")
+            {
+                // expected, noop
+            } else {
+                println!("{}", s);
+            }
+        }));
+
+        first(Box::new(lazy(move || {
+            panic::catch_unwind(move || {
+                nested(Box::new(lazy(|| { Ok::<(), ()>(()) })))
+            }).expect_err("nested should panic");
+            *panicked2.lock().unwrap() = true;
+            Ok::<(), ()>(())
+        })));
+
+        panic::set_hook(prev_hook);
+
+        assert!(*panicked.lock().unwrap(), "nested call should have panicked");
+    }
+
+    fn threadpool_new() -> Runtime {
+        Runtime::new().expect("rt new")
+    }
+
+    #[test]
+    fn run_in_run() {
+        test(tokio::run, tokio::run);
+    }
+
+    #[test]
+    fn threadpool_block_on_in_run() {
+        test(tokio::run, |fut| {
+            let mut rt = threadpool_new();
+            rt.block_on(fut).unwrap();
+        });
+    }
+
+    #[test]
+    fn threadpool_block_on_all_in_run() {
+        test(tokio::run, |fut| {
+            let rt = threadpool_new();
+            rt.block_on_all(fut).unwrap();
+        });
+    }
+
+    #[test]
+    fn current_thread_block_on_all_in_run() {
+        test(tokio::run, |fut| {
+            current_thread::block_on_all(fut).unwrap();
+        });
+    }
+}
+
+#[test]
+fn runtime_reactor_handle() {
+    #![allow(deprecated)]
+
+    use futures::Stream;
+    use std::net::{
+        TcpListener as StdListener,
+        TcpStream as StdStream,
+    };
+
+    let rt = Runtime::new().unwrap();
+
+    let std_listener = StdListener::bind("127.0.0.1:0").unwrap();
+    let tk_listener = TcpListener::from_std(std_listener, rt.handle()).unwrap();
+
+    let addr = tk_listener.local_addr().unwrap();
+
+    // Spawn a thread since we are avoiding the runtime
+    let th = thread::spawn(|| {
+        for _ in tk_listener.incoming().take(1).wait() {
+        }
+    });
+
+    let _ = StdStream::connect(&addr).unwrap();
+
+    th.join().unwrap();
+}
+
+#[test]
+fn after_start_and_before_stop_is_called() {
+    let _ = env_logger::try_init();
+
+    let after_start = Arc::new(atomic::AtomicUsize::new(0));
+    let before_stop = Arc::new(atomic::AtomicUsize::new(0));
+
+    let after_inner = after_start.clone();
+    let before_inner = before_stop.clone();
+    let runtime = tokio::runtime::Builder::new()
+            .after_start(move || { after_inner.clone().fetch_add(1, atomic::Ordering::Relaxed); })
+            .before_stop(move || { before_inner.clone().fetch_add(1, atomic::Ordering::Relaxed); })
+            .build()
+            .unwrap();
+
+    runtime.block_on_all(create_client_server_future()).unwrap();
+
+    assert!(after_start.load(atomic::Ordering::Relaxed) > 0);
+    assert!(before_stop.load(atomic::Ordering::Relaxed) > 0);
 }

tests/timer.rs

@@ -80,6 +80,7 @@ fn deadline() {
     let when = Instant::now() + Duration::from_millis(20);
     let (tx, rx) = mpsc::channel();
 
+    #[allow(deprecated)]
     tokio::run({
         future::empty::<(), ()>()
             .deadline(when)
@@ -92,3 +93,24 @@ fn deadline() {
 
     rx.recv().unwrap();
 }
+
+#[test]
+fn timeout() {
+    use futures::future;
+
+    let _ = env_logger::try_init();
+
+    let (tx, rx) = mpsc::channel();
+
+    tokio::run({
+        future::empty::<(), ()>()
+            .timeout(Duration::from_millis(20))
+            .then(move |res| {
+                assert!(res.is_err());
+                tx.send(()).unwrap();
+                Ok(())
+            })
+    });
+
+    rx.recv().unwrap();
+}

tokio-async-await/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "tokio-async-await"
+
+# When releasing to crates.io:
+# - Update html_root_url.
+version = "0.1.4"
+authors = ["Carl Lerche <[email protected]>"]
+license = "MIT"
+repository = "https://github.com/tokio-rs/tokio"
+homepage = "https://tokio.rs"
+documentation = "https://docs.rs/tokio-async-await/0.1.3"
+description = """
+Experimental async/await support for Tokio
+"""
+categories = ["asynchronous"]
+
+[features]
+# This feature comes with no promise of stability. Things will
+# break with each patch release. Use at your own risk.
+async-await-preview = ["futures/nightly"]
+
+[dependencies]
+futures = "0.1.23"
+tokio-io = { version = "0.1.7", path = "../tokio-io" }
+
+[dev-dependencies]
+bytes = "0.4.9"
+tokio = { version = "0.1.8", path = ".." }
+# tokio-codec = { version = "0.1.0", path = "../tokio-codec" }
+hyper = "0.12.8"

tokio-async-await/LICENSE

@@ -0,0 +1,52 @@
+Copyright (c) 2018 Tokio Contributors
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+
+Copyright (c) 2016 futures-rs authors
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+

tokio-async-await/README.md

@@ -0,0 +1,54 @@
+# Tokio async/await preview
+
+This crate provides a preview of Tokio with async / await support. It is a shim
+layer on top of `tokio`.
+
+**This crate requires Rust nightly and does not provide API stability
+guarantees. You are living on the edge here.**
+
+## Usage
+
+To use this crate, you need to start with a Rust 2018 edition crate.
+
+Add this to your `Cargo.toml`:
+
+```toml
+# In the `[packages]` section
+edition = "2018"
+
+# In the `[dependencies]` section
+tokio = {version = "0.1.0", features = ["async-await-preview"]}
+```
+
+Then, get started. In your application, add:
+
+```rust
+// The nightly features that are commonly needed with async / await
+#![feature(await_macro, async_await, futures_api)]
+
+// This pulls in the `tokio-async-await` crate. While Rust 2018 doesn't require
+// `extern crate`, we need to pull in the macros.
+#[macro_use]
+extern crate tokio;
+
+fn main() {
+    // And we are async...
+    tokio::run_async(async {
+        println!("Hello");
+    });
+}
+```
+
+Because nightly is required, run the app with `cargo +nightly run`
+
+Check the [examples](examples) directory for more.
+
+## License
+
+This project is licensed under the [MIT license](LICENSE).
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in Tokio by you, shall be licensed as MIT, without any additional
+terms or conditions.

tokio-async-await/examples/.cargo/config

@@ -0,0 +1,2 @@
+[build]
+target-dir = "../../target"

tokio-async-await/examples/Cargo.toml

@@ -0,0 +1,49 @@
+[package]
+name = "examples"
+edition = "2018"
+version = "0.1.0"
+authors = ["Carl Lerche <[email protected]>"]
+license = "MIT"
+
+# Break out of the parent workspace
+[workspace]
+
+[[bin]]
+name = "chat"
+path = "src/chat.rs"
+
+[[bin]]
+name = "echo_client"
+path = "src/echo_client.rs"
+
+[[bin]]
+name = "echo_server"
+path = "src/echo_server.rs"
+
+[[bin]]
+name = "hyper"
+path = "src/hyper.rs"
+
+[dependencies]
+tokio = { version = "0.1.0", path = "../..", features = ["async-await-preview"] }
+futures = "0.1.23"
+bytes = "0.4.9"
+hyper = "0.12.8"
+
+# Avoid using crates.io for Tokio dependencies
+[patch.crates-io]
+tokio = { path = "../.." }
+tokio-async-await  = { path = "../" }
+tokio-codec = { path = "../../tokio-codec" }
+tokio-current-thread = { path = "../../tokio-current-thread" }
+tokio-executor = { path = "../../tokio-executor" }
+tokio-fs = { path = "../../tokio-fs" }
+tokio-io = { path = "../../tokio-io" }
+tokio-reactor = { path = "../../tokio-reactor" }
+tokio-signal = { path = "../../tokio-signal" }
+tokio-tcp = { path = "../../tokio-tcp" }
+tokio-threadpool = { path = "../../tokio-threadpool" }
+tokio-timer = { path = "../../tokio-timer" }
+tokio-tls = { path = "../../tokio-tls" }
+tokio-udp = { path = "../../tokio-udp" }
+tokio-uds = { path = "../../tokio-uds" }

tokio-async-await/examples/README.md

@@ -0,0 +1,5 @@
+# Tokio async/await examples
+
+These are a separate crate in order to work around some cargo bugs. It also
+allows `[patch]` to be used in `Cargo.toml` to ensure the correct lib versions
+are being pulled in.

tokio-async-await/examples/src/chat.rs

@@ -0,0 +1,135 @@
+#![feature(await_macro, async_await, futures_api)]
+
+#[macro_use]
+extern crate tokio;
+extern crate futures; // v0.1
+
+use tokio::codec::{LinesCodec, Decoder};
+use tokio::net::{TcpListener, TcpStream};
+use tokio::prelude::*;
+
+use futures::sync::mpsc;
+
+use std::collections::HashMap;
+use std::io;
+use std::net::SocketAddr;
+use std::sync::{Arc, Mutex};
+
+/// Shorthand for the transmit half of the message channel.
+type Tx = mpsc::UnboundedSender<String>;
+
+struct Shared {
+    peers: HashMap<SocketAddr, Tx>,
+}
+
+impl Shared {
+    /// Create a new, empty, instance of `Shared`.
+    fn new() -> Self {
+        Shared {
+            peers: HashMap::new(),
+        }
+    }
+}
+
+async fn process(stream: TcpStream, state: Arc<Mutex<Shared>>) -> io::Result<()> {
+    let addr = stream.peer_addr().unwrap();
+    let mut lines = LinesCodec::new().framed(stream);
+
+    // Extract the peer's name
+    let name = match await!(lines.next()) {
+        Some(name) => name?,
+        None => {
+            // Disconnected early
+            return Ok(());
+        }
+    };
+
+    println!("`{}` is joining the chat", name);
+
+    let (tx, mut rx) = mpsc::unbounded();
+
+    // Register the socket
+    state.lock().unwrap()
+        .peers.insert(addr, tx);
+
+    // Split the `lines` handle into send and recv handles. This allows spawning
+    // separate tasks.
+    let (mut lines_tx, mut lines_rx) = lines.split();
+
+    // Spawn a task that receives all lines broadcasted to us from other peers
+    // and writes it to the client.
+    tokio::spawn_async(async move {
+        while let Some(line) = await!(rx.next()) {
+            let line = line.unwrap();
+            await!(lines_tx.send_async(line));
+        }
+    });
+
+    // Use the current task to read lines from the socket and broadcast them to
+    // other peers.
+    while let Some(message) = await!(lines_rx.next()) {
+        // TODO: Error handling
+        let message = message.unwrap();
+
+        let mut line = name.clone();
+        line.push_str(": ");
+        line.push_str(&message);
+        line.push_str("\r\n");
+
+        let state = state.lock().unwrap();
+
+        for (peer_addr, tx) in &state.peers {
+            if *peer_addr != addr {
+                // TODO: Error handling
+                tx.unbounded_send(line.clone()).unwrap();
+            }
+        }
+    }
+
+    // Remove the client from the shared state. Doing so will also result in the
+    // tx task to terminate.
+    state.lock().unwrap()
+        .peers.remove(&addr)
+        .expect("bug");
+
+    Ok(())
+}
+
+fn main() {
+    // Create the shared state. This is how all the peers communicate.
+    //
+    // The server task will hold a handle to this. For every new client, the
+    // `state` handle is cloned and passed into the task that processes the
+    // client connection.
+    let state = Arc::new(Mutex::new(Shared::new()));
+
+    let addr = "127.0.0.1:6142".parse().unwrap();
+
+    // Bind a TCP listener to the socket address.
+    //
+    // Note that this is the Tokio TcpListener, which is fully async.
+    let listener = TcpListener::bind(&addr).unwrap();
+
+    println!("server running on localhost:6142");
+
+    // Start the Tokio runtime.
+    tokio::run_async(async move {
+        let mut incoming = listener.incoming();
+
+        while let Some(stream) = await!(incoming.next()) {
+            let stream = match stream {
+                Ok(stream) => stream,
+                Err(_) => continue,
+            };
+
+            let state = state.clone();
+
+            tokio::spawn_async(async move {
+                if let Err(_) = await!(process(stream, state)) {
+                    eprintln!("failed to process connection");
+                }
+            });
+        }
+    });
+}
+

tokio-async-await/examples/src/echo_client.rs

@@ -0,0 +1,53 @@
+#![feature(await_macro, async_await, futures_api)]
+
+#[macro_use]
+extern crate tokio;
+
+use tokio::net::TcpStream;
+use tokio::prelude::*;
+
+use std::io;
+use std::net::SocketAddr;
+
+const MESSAGES: &[&str] = &[
+    "hello",
+    "world",
+    "one two three",
+];
+
+async fn run_client(addr: &SocketAddr) -> io::Result<()> {
+    let mut stream = await!(TcpStream::connect(addr))?;
+
+    // Buffer to read into
+    let mut buf = [0; 128];
+
+    for msg in MESSAGES {
+        println!(" > write = {:?}", msg);
+
+        // Write the message to the server
+        await!(stream.write_all_async(msg.as_bytes()))?;
+
+        // Read the message back from the server
+        await!(stream.read_exact_async(&mut buf[..msg.len()]))?;
+
+        assert_eq!(&buf[..msg.len()], msg.as_bytes());
+    }
+
+    Ok(())
+}
+
+fn main() {
+    use std::env;
+
+    let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
+    let addr = addr.parse::<SocketAddr>().unwrap();
+
+    // Connect to the echo serveer
+
+    tokio::run_async(async move {
+        match await!(run_client(&addr)) {
+            Ok(_) => println!("done."),
+            Err(e) => eprintln!("echo client failed; error = {:?}", e),
+        }
+    });
+}

tokio-async-await/examples/src/echo_server.rs

@@ -0,0 +1,45 @@
+#![feature(await_macro, async_await)]
+
+#[macro_use]
+extern crate tokio;
+
+use tokio::net::{TcpListener, TcpStream};
+use tokio::prelude::*;
+
+use std::net::SocketAddr;
+
+fn handle(mut stream: TcpStream) {
+    tokio::spawn_async(async move {
+        let mut buf = [0; 1024];
+
+        loop {
+            match await!(stream.read_async(&mut buf)).unwrap() {
+                0 => break, // Socket closed
+                n => {
+                    // Send the data back
+                    await!(stream.write_all_async(&buf[0..n])).unwrap();
+                }
+            }
+        }
+    });
+}
+
+fn main() {
+    use std::env;
+
+    let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
+    let addr = addr.parse::<SocketAddr>().unwrap();
+
+    // Bind the TCP listener
+    let listener = TcpListener::bind(&addr).unwrap();
+    println!("Listening on: {}", addr);
+
+    tokio::run_async(async {
+        let mut incoming = listener.incoming();
+
+        while let Some(stream) = await!(incoming.next()) {
+            let stream = stream.unwrap();
+            handle(stream);
+        }
+    });
+}

tokio-async-await/examples/src/hyper.rs

@@ -0,0 +1,33 @@
+#![feature(await_macro, async_await, futures_api)]
+
+#[macro_use]
+extern crate tokio;
+extern crate hyper;
+
+use tokio::prelude::*;
+use hyper::Client;
+
+use std::time::Duration;
+use std::str;
+
+pub fn main() {
+    tokio::run_async(async {
+        let client = Client::new();
+
+        let uri = "http://httpbin.org/ip".parse().unwrap();
+
+        let response = await!({
+            client.get(uri)
+                .timeout(Duration::from_secs(10))
+        }).unwrap();
+
+        println!("Response: {}", response.status());
+
+        let mut body = response.into_body();
+
+        while let Some(chunk) = await!(body.next()) {
+            let chunk = chunk.unwrap();
+            println!("chunk = {}", str::from_utf8(&chunk[..]).unwrap());
+        }
+    });
+}

tokio-async-await/src/await.rs

@@ -0,0 +1,16 @@
+/// Wait for a future to complete.
+#[macro_export]
+macro_rules! await {
+    ($e:expr) => {{
+        use $crate::std_await;
+        #[allow(unused_imports)]
+        use $crate::compat::forward::IntoAwaitable as IntoAwaitableForward;
+        #[allow(unused_imports)]
+        use $crate::compat::backward::IntoAwaitable as IntoAwaitableBackward;
+
+        #[allow(unused_mut)]
+        let mut e = $e;
+        let e = e.into_awaitable();
+        std_await!(e)
+    }}
+}

tokio-async-await/src/compat/backward.rs

@@ -0,0 +1,89 @@
+use futures::{Future, Poll};
+
+use std::pin::Pin;
+use std::future::{
+    Future as StdFuture,
+};
+use std::ptr::NonNull;
+use std::task::{
+    LocalWaker,
+    Poll as StdPoll,
+    UnsafeWake,
+    Waker,
+};
+
+/// Convert an 0.3 `Future` to an 0.1 `Future`.
+#[derive(Debug)]
+pub struct Compat<T>(Pin<Box<T>>);
+
+impl<T> Compat<T> {
+    /// Create a new `Compat` backed by `future`.
+    pub fn new(future: T) -> Compat<T> {
+        Compat(Box::pinned(future))
+    }
+}
+
+/// Convert a value into one that can be used with `await!`.
+pub trait IntoAwaitable {
+    type Awaitable;
+
+    fn into_awaitable(self) -> Self::Awaitable;
+}
+
+impl<T> IntoAwaitable for T
+where T: StdFuture,
+{
+    type Awaitable = Self;
+
+    fn into_awaitable(self) -> Self {
+        self
+    }
+}
+
+impl<T, Item, Error> Future for Compat<T>
+where T: StdFuture<Output = Result<Item, Error>>,
+{
+    type Item = Item;
+    type Error = Error;
+
+    fn poll(&mut self) -> Poll<Item, Error> {
+        use futures::Async::*;
+
+        let local_waker = noop_local_waker();
+
+        let res = self.0.as_mut().poll(&local_waker);
+
+        match res {
+            StdPoll::Ready(Ok(val)) => Ok(Ready(val)),
+            StdPoll::Ready(Err(err)) => Err(err),
+            StdPoll::Pending => Ok(NotReady),
+        }
+    }
+}
+
+// ===== NoopWaker =====
+
+struct NoopWaker;
+
+fn noop_local_waker() -> LocalWaker {
+    let w: NonNull<NoopWaker> = NonNull::dangling();
+    unsafe { LocalWaker::new(w) }
+}
+
+fn noop_waker() -> Waker {
+    let w: NonNull<NoopWaker> = NonNull::dangling();
+    unsafe { Waker::new(w) }
+}
+
+unsafe impl UnsafeWake for NoopWaker {
+    unsafe fn clone_raw(&self) -> Waker {
+        noop_waker()
+    }
+
+    unsafe fn drop_raw(&self) {
+    }
+
+    unsafe fn wake(&self) {
+        panic!("NoopWake cannot wake");
+    }
+}

tokio-async-await/src/compat/forward.rs

@@ -0,0 +1,68 @@
+
+use futures::{Future, Async};
+
+use std::marker::Unpin;
+use std::future::Future as StdFuture;
+use std::pin::Pin;
+use std::task::{LocalWaker, Poll as StdPoll};
+
+/// Converts an 0.1 `Future` into an 0.3 `Future`.
+#[derive(Debug)]
+pub struct Compat<T>(T);
+
+pub(crate) fn convert_poll<T, E>(poll: Result<Async<T>, E>) -> StdPoll<Result<T, E>> {
+    use futures::Async::{Ready, NotReady};
+
+    match poll {
+        Ok(Ready(val)) => StdPoll::Ready(Ok(val)),
+        Ok(NotReady) => StdPoll::Pending,
+        Err(err) => StdPoll::Ready(Err(err)),
+    }
+}
+
+pub(crate) fn convert_poll_stream<T, E>(
+    poll: Result<Async<Option<T>>, E>) -> StdPoll<Option<Result<T, E>>>
+{
+    use futures::Async::{Ready, NotReady};
+
+    match poll {
+        Ok(Ready(Some(val))) => StdPoll::Ready(Some(Ok(val))),
+        Ok(Ready(None)) => StdPoll::Ready(None),
+        Ok(NotReady) => StdPoll::Pending,
+        Err(err) => StdPoll::Ready(Some(Err(err))),
+    }
+}
+
+/// Convert a value into one that can be used with `await!`.
+pub trait IntoAwaitable {
+    type Awaitable;
+
+    /// Convert `self` into a value that can be used with `await!`.
+    fn into_awaitable(self) -> Self::Awaitable;
+}
+
+impl<T: Future + Unpin> IntoAwaitable for T {
+    type Awaitable = Compat<T>;
+
+    fn into_awaitable(self) -> Self::Awaitable {
+        Compat(self)
+    }
+}
+
+impl<T> StdFuture for Compat<T>
+where T: Future + Unpin
+{
+    type Output = Result<T::Item, T::Error>;
+
+    fn poll(mut self: Pin<&mut Self>, _lw: &LocalWaker) -> StdPoll<Self::Output> {
+        use futures::Async::{Ready, NotReady};
+
+        // TODO: wire in cx
+
+        match self.0.poll() {
+            Ok(Ready(val)) => StdPoll::Ready(Ok(val)),
+            Ok(NotReady) => StdPoll::Pending,
+            Err(e) => StdPoll::Ready(Err(e)),
+        }
+    }
+}

tokio-async-await/src/compat/mod.rs

@@ -0,0 +1,4 @@
+#![doc(hidden)]
+
+pub mod forward;
+pub mod backward;

tokio-async-await/src/io/flush.rs

@@ -0,0 +1,32 @@
+use tokio_io::AsyncWrite;
+
+
+use std::io;
+use std::future::Future;
+use std::marker::Unpin;
+use std::pin::Pin;
+use std::task::{LocalWaker, Poll};
+
+/// A future used to fully flush an I/O object.
+#[derive(Debug)]
+pub struct Flush<'a, T: ?Sized + 'a> {
+    writer: &'a mut T,
+}
+
+// Pin is never projected to fields
+impl<'a, T: ?Sized> Unpin for Flush<'a, T> {}
+
+impl<'a, T: AsyncWrite + ?Sized> Flush<'a, T> {
+    pub(super) fn new(writer: &'a mut T) -> Flush<'a, T> {
+        Flush { writer }
+    }
+}
+
+impl<'a, T: AsyncWrite + ?Sized> Future for Flush<'a, T> {
+    type Output = io::Result<()>;
+
+    fn poll(mut self: Pin<&mut Self>, _wx: &LocalWaker) -> Poll<Self::Output> {
+        use crate::compat::forward::convert_poll;
+        convert_poll(self.writer.poll_flush())
+    }
+}

tokio-async-await/src/io/mod.rs

@@ -0,0 +1,192 @@
+//! Use I/O with `async` / `await`.
+
+mod flush;
+mod read;
+mod read_exact;
+mod write;
+mod write_all;
+
+pub use self::flush::Flush;
+pub use self::read::Read;
+pub use self::read_exact::ReadExact;
+pub use self::write::Write;
+pub use self::write_all::WriteAll;
+
+use tokio_io::{AsyncRead, AsyncWrite};
+
+/// An extension trait which adds utility methods to `AsyncRead` types.
+pub trait AsyncReadExt: AsyncRead {
+    /// Tries to read some bytes directly into the given `buf` in an
+    /// asynchronous manner, returning a future.
+    ///
+    /// The returned future will resolve to the number of bytes read once the read
+    /// operation is completed.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(async_await, await_macro, futures_api)]
+    /// tokio::run_async(async {
+    /// // The extension trait can also be imported with
+    /// // `use tokio::prelude::*`.
+    /// use tokio::prelude::AsyncReadExt;
+    /// use std::io::Cursor;
+    ///
+    /// let mut reader = Cursor::new([1, 2, 3, 4]);
+    /// let mut output = [0u8; 5];
+    ///
+    /// let bytes = await!(reader.read_async(&mut output[..])).unwrap();
+    ///
+    /// // This is only guaranteed to be 4 because `&[u8]` is a synchronous
+    /// // reader. In a real system you could get anywhere from 1 to
+    /// // `output.len()` bytes in a single read.
+    /// assert_eq!(bytes, 4);
+    /// assert_eq!(output, [1, 2, 3, 4, 0]);
+    /// });
+    /// ```
+    fn read_async<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self> {
+        Read::new(self, buf)
+    }
+
+    /// Creates a future which will read exactly enough bytes to fill `buf`,
+    /// returning an error if end of file (EOF) is hit sooner.
+    ///
+    /// The returned future will resolve once the read operation is completed.
+    ///
+    /// In the case of an error the buffer and the object will be discarded, with
+    /// the error yielded.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(async_await, await_macro, futures_api)]
+    /// tokio::run_async(async {
+    /// // The extension trait can also be imported with
+    /// // `use tokio::prelude::*`.
+    /// use tokio::prelude::AsyncReadExt;
+    /// use std::io::Cursor;
+    ///
+    /// let mut reader = Cursor::new([1, 2, 3, 4]);
+    /// let mut output = [0u8; 4];
+    ///
+    /// await!(reader.read_exact_async(&mut output)).unwrap();
+    ///
+    /// assert_eq!(output, [1, 2, 3, 4]);
+    /// });
+    /// ```
+    ///
+    /// ## EOF is hit before `buf` is filled
+    ///
+    /// ```
+    /// #![feature(async_await, await_macro, futures_api)]
+    /// tokio::run_async(async {
+    /// // The extension trait can also be imported with
+    /// // `use tokio::prelude::*`.
+    /// use tokio::prelude::AsyncReadExt;
+    /// use std::io::{self, Cursor};
+    ///
+    /// let mut reader = Cursor::new([1, 2, 3, 4]);
+    /// let mut output = [0u8; 5];
+    ///
+    /// let result = await!(reader.read_exact_async(&mut output));
+    ///
+    /// assert_eq!(result.unwrap_err().kind(), io::ErrorKind::UnexpectedEof);
+    /// });
+    /// ```
+    fn read_exact_async<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExact<'a, Self> {
+        ReadExact::new(self, buf)
+    }
+}
+
+/// An extension trait which adds utility methods to `AsyncWrite` types.
+pub trait AsyncWriteExt: AsyncWrite {
+    /// Write data into this object.
+    ///
+    /// Creates a future that will write the entire contents of the buffer `buf` into
+    /// this `AsyncWrite`.
+    ///
+    /// The returned future will not complete until all the data has been written.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(async_await, await_macro, futures_api)]
+    /// tokio::run_async(async {
+    /// // The extension trait can also be imported with
+    /// // `use tokio::prelude::*`.
+    /// use tokio::prelude::AsyncWriteExt;
+    /// use std::io::Cursor;
+    ///
+    /// let mut buf = [0u8; 5];
+    /// let mut writer = Cursor::new(&mut buf[..]);
+    ///
+    /// let n = await!(writer.write_async(&[1, 2, 3, 4])).unwrap();
+    ///
+    /// assert_eq!(writer.into_inner()[..n], [1, 2, 3, 4, 0][..n]);
+    /// });
+    /// ```
+    fn write_async<'a>(&'a mut self, buf: &'a [u8]) -> Write<'a, Self> {
+        Write::new(self, buf)
+    }
+
+    /// Write an entire buffer into this object.
+    ///
+    /// Creates a future that will write the entire contents of the buffer `buf` into
+    /// this `AsyncWrite`.
+    ///
+    /// The returned future will not complete until all the data has been written.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(async_await, await_macro, futures_api)]
+    /// tokio::run_async(async {
+    /// // The extension trait can also be imported with
+    /// // `use tokio::prelude::*`.
+    /// use tokio::prelude::AsyncWriteExt;
+    /// use std::io::Cursor;
+    ///
+    /// let mut buf = [0u8; 5];
+    /// let mut writer = Cursor::new(&mut buf[..]);
+    ///
+    /// await!(writer.write_all_async(&[1, 2, 3, 4])).unwrap();
+    ///
+    /// assert_eq!(writer.into_inner(), [1, 2, 3, 4, 0]);
+    /// });
+    /// ```
+    fn write_all_async<'a>(&'a mut self, buf: &'a [u8]) -> WriteAll<'a, Self> {
+        WriteAll::new(self, buf)
+    }
+
+    /// Creates a future which will entirely flush this `AsyncWrite`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(async_await, await_macro, futures_api)]
+    /// tokio::run_async(async {
+    /// // The extension trait can also be imported with
+    /// // `use tokio::prelude::*`.
+    /// use tokio::prelude::AsyncWriteExt;
+    /// use std::io::{BufWriter, Cursor};
+    ///
+    /// let mut output = [0u8; 5];
+    ///
+    /// {
+    ///     let mut writer = Cursor::new(&mut output[..]);
+    ///     let mut buffered = BufWriter::new(writer);
+    ///     await!(buffered.write_all_async(&[1, 2])).unwrap();
+    ///     await!(buffered.write_all_async(&[3, 4])).unwrap();
+    ///     await!(buffered.flush_async()).unwrap();
+    /// }
+    ///
+    /// assert_eq!(output, [1, 2, 3, 4, 0]);
+    /// });
+    /// ```
+    fn flush_async<'a>(&mut self) -> Flush<Self> {
+        Flush::new(self)
+    }
+}
+
+impl<T: AsyncRead + ?Sized> AsyncReadExt for T {}
+impl<T: AsyncWrite + ?Sized> AsyncWriteExt for T {}

tokio-async-await/src/io/read.rs

@@ -0,0 +1,38 @@
+use tokio_io::AsyncRead;
+
+use std::future::Future;
+use std::task::{self, Poll};
+
+use std::io;
+use std::marker::Unpin;
+use std::pin::Pin;
+
+/// A future which can be used to read bytes.
+#[derive(Debug)]
+pub struct Read<'a, T: ?Sized + 'a> {
+    reader: &'a mut T,
+    buf: &'a mut [u8],
+}
+
+// Pinning is never projected to fields
+impl<'a, T: ?Sized> Unpin for Read<'a, T> {}
+
+impl<'a, T: AsyncRead + ?Sized> Read<'a, T> {
+    pub(super) fn new(reader: &'a mut T, buf: &'a mut [u8]) -> Read<'a, T> {
+        Read {
+            reader,
+            buf,
+        }
+    }
+}
+
+impl<'a, T: AsyncRead + ?Sized> Future for Read<'a, T> {
+    type Output = io::Result<usize>;
+
+    fn poll(mut self: Pin<&mut Self>, _lw: &task::LocalWaker) -> Poll<Self::Output> {
+        use crate::compat::forward::convert_poll;
+
+        let this = &mut *self;
+        convert_poll(this.reader.poll_read(this.buf))
+    }
+}

tokio-async-await/src/io/read_exact.rs

@@ -0,0 +1,56 @@
+use tokio_io::AsyncRead;
+
+use std::future::Future;
+use std::task::{self, Poll};
+
+use std::io;
+use std::marker::Unpin;
+use std::mem;
+use std::pin::Pin;
+
+/// A future which can be used to read exactly enough bytes to fill a buffer.
+#[derive(Debug)]
+pub struct ReadExact<'a, T: ?Sized + 'a> {
+    reader: &'a mut T,
+    buf: &'a mut [u8],
+}
+
+// Pinning is never projected to fields
+impl<'a, T: ?Sized> Unpin for ReadExact<'a, T> {}
+
+impl<'a, T: AsyncRead + ?Sized> ReadExact<'a, T> {
+    pub(super) fn new(reader: &'a mut T, buf: &'a mut [u8]) -> ReadExact<'a, T> {
+        ReadExact {
+            reader,
+            buf,
+        }
+    }
+}
+
+fn eof() -> io::Error {
+    io::Error::new(io::ErrorKind::UnexpectedEof, "early eof")
+}
+
+impl<'a, T: AsyncRead + ?Sized> Future for ReadExact<'a, T> {
+    type Output = io::Result<()>;
+
+    fn poll(mut self: Pin<&mut Self>, _lw: &task::LocalWaker) -> Poll<Self::Output> {
+        use crate::compat::forward::convert_poll;
+
+        let this = &mut *self;
+
+        while !this.buf.is_empty() {
+            let n = try_ready!(convert_poll(this.reader.poll_read(this.buf)));
+
+            {
+                let (_, rest) = mem::replace(&mut this.buf, &mut []).split_at_mut(n);
+                this.buf = rest;
+            }
+            if n == 0 {
+                return Poll::Ready(Err(eof()))
+            }
+        }
+
+        Poll::Ready(Ok(()))
+    }
+}

tokio-async-await/src/io/write.rs

@@ -0,0 +1,38 @@
+use tokio_io::AsyncWrite;
+
+use std::future::Future;
+use std::task::{self, Poll};
+
+use std::io;
+use std::marker::Unpin;
+use std::pin::Pin;
+
+/// A future used to write data.
+#[derive(Debug)]
+pub struct Write<'a, T: 'a + ?Sized> {
+    writer: &'a mut T,
+    buf: &'a [u8],
+}
+
+// Pinning is never projected to fields
+impl<'a, T: ?Sized> Unpin for Write<'a, T> {}
+
+impl<'a, T: AsyncWrite + ?Sized> Write<'a, T> {
+    pub(super) fn new(writer: &'a mut T, buf: &'a [u8]) -> Write<'a, T> {
+        Write {
+            writer,
+            buf,
+        }
+    }
+}
+
+impl<'a, T: AsyncWrite + ?Sized> Future for Write<'a, T> {
+    type Output = io::Result<usize>;
+
+    fn poll(mut self: Pin<&mut Self>, _lw: &task::LocalWaker) -> Poll<io::Result<usize>> {
+        use crate::compat::forward::convert_poll;
+
+        let this = &mut *self;
+        convert_poll(this.writer.poll_write(this.buf))
+    }
+}

tokio-async-await/src/io/write_all.rs

@@ -0,0 +1,57 @@
+use tokio_io::AsyncWrite;
+
+use std::future::Future;
+use std::task::{self, Poll};
+
+use std::io;
+use std::marker::Unpin;
+use std::mem;
+use std::pin::Pin;
+
+/// A future used to write the entire contents of a buffer.
+#[derive(Debug)]
+pub struct WriteAll<'a, T: ?Sized + 'a> {
+    writer: &'a mut T,
+    buf: &'a [u8],
+}
+
+// Pinning is never projected to fields
+impl<'a, T: ?Sized> Unpin for WriteAll<'a, T> {}
+
+impl<'a, T: AsyncWrite + ?Sized> WriteAll<'a, T> {
+    pub(super) fn new(writer: &'a mut T, buf: &'a [u8]) -> WriteAll<'a, T> {
+        WriteAll {
+            writer,
+            buf,
+        }
+    }
+}
+
+fn zero_write() -> io::Error {
+    io::Error::new(io::ErrorKind::WriteZero, "zero-length write")
+}
+
+impl<'a, T: AsyncWrite + ?Sized> Future for WriteAll<'a, T> {
+    type Output = io::Result<()>;
+
+    fn poll(mut self: Pin<&mut Self>, _lw: &task::LocalWaker) -> Poll<io::Result<()>> {
+        use crate::compat::forward::convert_poll;
+
+        let this = &mut *self;
+
+        while !this.buf.is_empty() {
+            let n = try_ready!(convert_poll(this.writer.poll_write(this.buf)));
+
+            {
+                let (_, rest) = mem::replace(&mut this.buf, &[]).split_at(n);
+                this.buf = rest;
+            }
+
+            if n == 0 {
+                return Poll::Ready(Err(zero_write()))
+            }
+        }
+
+        Poll::Ready(Ok(()))
+    }
+}

tokio-async-await/src/lib.rs

@@ -0,0 +1,115 @@
+#![cfg(feature = "async-await-preview")]
+#![feature(
+    rust_2018_preview,
+    arbitrary_self_types,
+    async_await,
+    await_macro,
+    futures_api,
+    pin,
+    )]
+
+#![doc(html_root_url = "https://docs.rs/tokio-async-await/0.1.4")]
+#![deny(missing_docs, missing_debug_implementations)]
+#![cfg_attr(test, deny(warnings))]
+
+//! A preview of Tokio w/ `async` / `await` support.
+
+extern crate futures;
+extern crate tokio_io;
+
+/// Extracts the successful type of a `Poll<Result<T, E>>`.
+///
+/// This macro bakes in propagation of `Pending` and `Err` signals by returning early.
+macro_rules! try_ready {
+    ($x:expr) => {
+        match $x {
+            std::task::Poll::Ready(Ok(x)) => x,
+            std::task::Poll::Ready(Err(e)) =>
+                return std::task::Poll::Ready(Err(e.into())),
+            std::task::Poll::Pending =>
+                return std::task::Poll::Pending,
+        }
+    }
+}
+
+#[macro_use]
+mod await;
+pub mod compat;
+pub mod io;
+pub mod sink;
+pub mod stream;
+
+/*
+pub mod prelude {
+    //! A "prelude" for users of the `tokio` crate.
+    //!
+    //! This prelude is similar to the standard library's prelude in that you'll
+    //! almost always want to import its entire contents, but unlike the standard
+    //! library's prelude you'll have to do so manually:
+    //!
+    //! ```
+    //! use tokio::prelude::*;
+    //! ```
+    //!
+    //! The prelude may grow over time as additional items see ubiquitous use.
+
+    pub use tokio_main::prelude::*;
+
+    #[doc(inline)]
+    pub use crate::async_await::{
+        io::{
+            AsyncReadExt,
+            AsyncWriteExt,
+        },
+        sink::{
+            SinkExt,
+        },
+        stream::{
+            StreamExt,
+        },
+    };
+}
+*/
+
+// Rename the `await` macro in `std`. This is used by the redefined
+// `await` macro in this crate.
+#[doc(hidden)]
+pub use std::await as std_await;
+
+/*
+use std::future::{Future as StdFuture};
+
+fn run<T: futures::Future<Item = (), Error = ()>>(t: T) {
+    drop(t);
+}
+
+async fn map_ok<T: StdFuture>(future: T) -> Result<(), ()> {
+    let _ = await!(future);
+    Ok(())
+}
+
+/// Like `tokio::run`, but takes an `async` block
+pub fn run_async<F>(future: F)
+where F: StdFuture<Output = ()> + Send + 'static,
+{
+    use async_await::compat::backward;
+    let future = backward::Compat::new(map_ok(future));
+
+    run(future);
+    unimplemented!();
+}
+*/
+
+/*
+/// Like `tokio::spawn`, but takes an `async` block
+pub fn spawn_async<F>(future: F)
+where F: StdFuture<Output = ()> + Send + 'static,
+{
+    use crate::async_await::compat::backward;
+
+    spawn(backward::Compat::new(async || {
+        let _ = await!(future);
+        Ok(())
+    }));
+}
+*/

tokio-async-await/src/sink/mod.rs

@@ -0,0 +1,26 @@
+//! Use sinks with `async` / `await`.
+
+mod send;
+
+pub use self::send::Send;
+
+use futures::Sink;
+
+use std::marker::Unpin;
+
+/// An extension trait which adds utility methods to `Sink` types.
+pub trait SinkExt: Sink {
+    /// Send an item into the sink.
+    ///
+    /// Note that, **because of the flushing requirement, it is usually better
+    /// to batch together items to send via `send_all`, rather than flushing
+    /// between each item.**
+    fn send_async(&mut self, item: Self::SinkItem) -> Send<Self>
+    where
+        Self: Sized + Unpin,
+    {
+        Send::new(self, item)
+    }
+}
+
+impl<T: Sink> SinkExt for T {}

tokio-async-await/src/sink/send.rs

@@ -0,0 +1,54 @@
+use futures::Sink;
+
+use std::future::Future;
+use std::task::{self, Poll};
+
+use std::marker::Unpin;
+use std::pin::Pin;
+
+/// Future for the `SinkExt::send_async` combinator, which sends a value to a
+/// sink and then waits until the sink has fully flushed.
+#[derive(Debug)]
+pub struct Send<'a, T: Sink + 'a + ?Sized> {
+    sink: &'a mut T,
+    item: Option<T::SinkItem>,
+}
+
+impl<T: Sink + Unpin + ?Sized> Unpin for Send<'_, T> {}
+
+impl<'a, T: Sink + Unpin + ?Sized> Send<'a, T> {
+    pub(super) fn new(sink: &'a mut T, item: T::SinkItem) -> Self {
+        Send {
+            sink,
+            item: Some(item),
+        }
+    }
+}
+
+impl<T: Sink + Unpin + ?Sized> Future for Send<'_, T> {
+    type Output = Result<(), T::SinkError>;
+
+    fn poll(mut self: Pin<&mut Self>, _lw: &task::LocalWaker) -> Poll<Self::Output> {
+        use crate::compat::forward::convert_poll;
+        use futures::AsyncSink::{Ready, NotReady};
+
+        if let Some(item) = self.item.take() {
+            match self.sink.start_send(item) {
+                Ok(Ready) => {}
+                Ok(NotReady(val)) => {
+                    self.item = Some(val);
+                    return Poll::Pending;
+                }
+                Err(err) => {
+                    return Poll::Ready(Err(err));
+                }
+            }
+        }
+
+        // we're done sending the item, but want to block on flushing the
+        // sink
+        try_ready!(convert_poll(self.sink.poll_complete()));
+
+        Poll::Ready(Ok(()))
+    }
+}

tokio-async-await/src/stream/mod.rs

@@ -0,0 +1,40 @@
+//! Use streams with `async` / `await`.
+
+mod next;
+
+pub use self::next::Next;
+
+use futures::Stream;
+
+use std::marker::Unpin;
+
+/// An extension trait which adds utility methods to `Stream` types.
+pub trait StreamExt: Stream {
+    /// Creates a future that resolves to the next item in the stream.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(await_macro, async_await)]
+    /// tokio::run_async(async {
+    /// // The extension trait can also be imported with
+    /// // `use tokio::prelude::*`.
+    /// use tokio::prelude::{stream, StreamExt};
+    ///
+    /// let mut stream = stream::iter_ok::<_, ()>(1..3);
+    ///
+    /// assert_eq!(await!(stream.next()), Some(Ok(1)));
+    /// assert_eq!(await!(stream.next()), Some(Ok(2)));
+    /// assert_eq!(await!(stream.next()), Some(Ok(3)));
+    /// assert_eq!(await!(stream.next()), None);
+    /// });
+    /// ```
+    fn next(&mut self) -> Next<Self>
+    where
+        Self: Sized + Unpin,
+    {
+        Next::new(self)
+    }
+}
+
+impl<T: Stream> StreamExt for T {}

tokio-async-await/src/stream/next.rs

@@ -0,0 +1,30 @@
+use futures::Stream;
+
+use std::future::Future;
+use std::marker::Unpin;
+use std::pin::Pin;
+use std::task::{LocalWaker, Poll};
+
+/// A future of the next element of a stream.
+#[derive(Debug)]
+pub struct Next<'a, T: 'a> {
+    stream: &'a mut T,
+}
+
+impl<'a, T: Stream + Unpin> Unpin for Next<'a, T> {}
+
+impl<'a, T: Stream + Unpin> Next<'a, T> {
+    pub(super) fn new(stream: &'a mut T) -> Next<'a, T> {
+        Next { stream }
+    }
+}
+
+impl<'a, T: Stream + Unpin> Future for Next<'a, T> {
+    type Output = Option<Result<T::Item, T::Error>>;
+
+    fn poll(mut self: Pin<&mut Self>, _lw: &LocalWaker) -> Poll<Self::Output> {
+        use crate::compat::forward::convert_poll_stream;
+
+        convert_poll_stream(self.stream.poll())
+    }
+}

tokio-buf/CHANGELOG.md

@@ -0,0 +1,3 @@
+# 0.1.0 (unreleased)
+
+* Initial release

tokio-buf/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "tokio-buf"
+
+# When releasing to crates.io:
+# - Update html_root_url.
+# - Update CHANGELOG.md.
+# - Create "v0.1.x" git tag.
+version = "0.1.0"
+authors = ["Carl Lerche <[email protected]>"]
+license = "MIT"
+repository = "https://github.com/tokio-rs/tokio"
+homepage = "https://tokio.rs"
+documentation = "https://docs.rs/tokio-buf/0.1.0"
+description = """
+Asynchronous stream of byte buffers
+"""
+categories = ["asynchronous"]
+
+[dependencies]
+bytes = { version = "0.4.10", features = [ "either" ] }
+either = "1.5"
+futures = "0.1.23"

tokio-buf/LICENSE

@@ -0,0 +1,25 @@
+Copyright (c) 2018 Tokio Contributors
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

tokio-buf/src/buf_stream/bytes.rs

@@ -0,0 +1,70 @@
+use BufStream;
+use buf_stream::errors::internal::Never;
+
+use bytes::{Bytes, BytesMut};
+use futures::Poll;
+
+use std::io;
+
+impl BufStream for Vec<u8> {
+    type Item = io::Cursor<Vec<u8>>;
+    type Error = Never;
+
+    fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
+        if self.is_empty() {
+            return Ok(None.into());
+        }
+
+        poll_bytes(self)
+    }
+}
+
+impl BufStream for &'static [u8] {
+    type Item = io::Cursor<&'static [u8]>;
+    type Error = Never;
+
+    fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
+        if self.is_empty() {
+            return Ok(None.into());
+        }
+
+        poll_bytes(self)
+    }
+}
+
+impl BufStream for Bytes {
+    type Item = io::Cursor<Bytes>;
+    type Error = Never;
+
+    fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
+        if self.is_empty() {
+            return Ok(None.into());
+        }
+
+        poll_bytes(self)
+    }
+}
+
+impl BufStream for BytesMut {
+    type Item = io::Cursor<BytesMut>;
+    type Error = Never;
+
+    fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
+        if self.is_empty() {
+            return Ok(None.into());
+        }
+
+        poll_bytes(self)
+    }
+}
+
+fn poll_bytes<T: Default>(buf: &mut T)
+    -> Poll<Option<io::Cursor<T>>, Never>
+{
+    use std::mem;
+
+    let bytes = mem::replace(buf, Default::default());
+    let buf = io::Cursor::new(bytes);
+
+    Ok(Some(buf).into())
+}

tokio-buf/src/buf_stream/chain.rs

@@ -0,0 +1,51 @@
+use super::{BufStream, SizeHint};
+
+use either::Either;
+use futures::Poll;
+
+/// A buf stream that sequences two buf streams together.
+///
+/// `Chain` values are produced by the `chain` function on `BufStream`.
+#[derive(Debug)]
+pub struct Chain<T, U> {
+    left: Option<T>,
+    right: U,
+}
+
+impl<T, U> Chain<T, U> {
+    pub(crate) fn new(left: T, right: U) -> Chain<T, U> {
+        Chain {
+            left: Some(left),
+            right,
+        }
+    }
+}
+
+impl<T, U> BufStream for Chain<T, U>
+where
+    T: BufStream,
+    U: BufStream<Error = T::Error>,
+{
+    type Item = Either<T::Item, U::Item>;
+    type Error = T::Error;
+
+    fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
+        if let Some(ref mut stream) = self.left {
+            let res = try_ready!(stream.poll_buf());
+
+            if res.is_some() {
+                return Ok(res.map(Either::Left).into());
+            }
+        }
+
+        self.left = None;
+
+        let res = try_ready!(self.right.poll_buf());
+        Ok(res.map(Either::Right).into())
+    }
+
+    fn size_hint(&self) -> SizeHint {
+        // TODO: Implement
+        SizeHint::default()
+    }
+}

tokio-buf/src/buf_stream/collect.rs

@@ -0,0 +1,103 @@
+use super::{BufStream, FromBufStream};
+
+use futures::{Future, Poll};
+
+/// Consumes a buf stream, collecting the data into a single byte container.
+///
+/// `Collect` values are produced by `BufStream::collect`.
+#[derive(Debug)]
+pub struct Collect<T, U>
+where
+    T: BufStream,
+    U: FromBufStream<T::Item>,
+{
+    stream: T,
+    builder: Option<U::Builder>,
+}
+
+/// Errors returned from `Collect` future.
+#[derive(Debug)]
+pub struct CollectError<T, U> {
+    inner: Error<T, U>,
+}
+
+#[derive(Debug)]
+enum Error<T, U> {
+    Stream(T),
+    Collect(U),
+}
+
+impl<T, U> Collect<T, U>
+where
+    T: BufStream,
+    U: FromBufStream<T::Item>,
+{
+    pub(crate) fn new(stream: T) -> Collect<T, U> {
+        let builder = U::builder(&stream.size_hint());
+
+        Collect {
+            stream,
+            builder: Some(builder),
+        }
+    }
+}
+
+impl<T, U> Future for Collect<T, U>
+where
+    T: BufStream,
+    U: FromBufStream<T::Item>,
+{
+    type Item = U;
+    type Error = CollectError<T::Error, U::Error>;
+
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+        loop {
+            let res = self.stream.poll_buf()
+                .map_err(|err| {
+                    let inner = Error::Stream(err);
+                    CollectError { inner }
+                });
+
+            match try_ready!(res) {
+                Some(mut buf) => {
+                    let builder = self.builder.as_mut().expect("cannot poll after done");
+
+                    U::extend(builder, &mut buf, &self.stream.size_hint())
+                        .map_err(|err| {
+                            let inner = Error::Collect(err);
+                            CollectError { inner }
+                        })?;
+                }
+                None => {
+                    let builder = self.builder.take().expect("cannot poll after done");
+                    let value = U::build(builder)
+                        .map_err(|err| {
+                            let inner = Error::Collect(err);
+                            CollectError { inner }
+                        })?;
+                    return Ok(value.into());
+                }
+            }
+        }
+    }
+}
+
+// ===== impl CollectError =====
+
+impl<T, U> CollectError<T, U> {
+    /// Returns `true` if the error was caused by polling the stream.
+    pub fn is_stream_err(&self) -> bool {
+        match self.inner {
+            Error::Stream(_) => true,
+            _ => false,
+        }
+    }
+
+    /// Returns `true` if the error happened while collecting the data.
+    pub fn is_collect_err(&self) -> bool {
+        match self.inner {
+            Error::Collect(_) => true,
+            _ => false,
+        }
+    }
+}

tokio-buf/src/buf_stream/errors.rs

@@ -0,0 +1,32 @@
+//! Error types
+
+pub use super::collect::CollectError;
+pub use super::from::CollectVecError;
+pub use super::limit::LimitError;
+
+// Being crate-private, we should be able to swap the type out in a
+// backwards compatible way.
+pub(crate) mod internal {
+    use std::{error, fmt};
+
+    /// An error that can never occur
+    pub enum Never {}
+
+    impl fmt::Debug for Never {
+        fn fmt(&self, _f: &mut fmt::Formatter) -> fmt::Result {
+            match *self {}
+        }
+    }
+
+    impl fmt::Display for Never {
+        fn fmt(&self, _f: &mut fmt::Formatter) -> fmt::Result {
+            match *self {}
+        }
+    }
+
+    impl error::Error for Never {
+        fn description(&self) -> &str {
+            match *self {}
+        }
+    }
+}

tokio-buf/src/buf_stream/from.rs

@@ -0,0 +1,110 @@
+use super::SizeHint;
+
+use bytes::{Buf, BufMut};
+
+use std::usize;
+
+/// Conversion from a `BufStream`.
+///
+/// By implementing `FromBufStream` for a type, you define how it will be
+/// created from a buf stream. This is common for types which describe byte
+/// storage of some kind.
+///
+/// `FromBufStream` is rarely called explicitly, and it is instead used through
+/// `BufStream`'s `collect` method.
+pub trait FromBufStream<T: Buf>: Sized {
+    /// Type that is used to build `Self` while the `BufStream` is being
+    /// consumed.
+    type Builder;
+
+    /// Error that might happen on conversion.
+    type Error;
+
+    /// Create a new, empty, builder. The provided `hint` can be used to inform
+    /// reserving capacity.
+    fn builder(hint: &SizeHint) -> Self::Builder;
+
+    /// Extend the builder with the `Buf`.
+    ///
+    /// This method is called whenever a new `Buf` value is obtained from the
+    /// buf stream.
+    ///
+    /// The provided size hint represents the state of the stream **after**
+    /// `buf` has been yielded. The lower bound represents the minimum amount of
+    /// data that will be provided after this call to `extend` returns.
+    fn extend(builder: &mut Self::Builder, buf: &mut T, hint: &SizeHint)
+        -> Result<(), Self::Error>;
+
+    /// Finalize the building of `Self`.
+    ///
+    /// Called once the buf stream is fully consumed.
+    fn build(builder: Self::Builder) -> Result<Self, Self::Error>;
+}
+
+/// Error returned from collecting into a `Vec<u8>`
+#[derive(Debug)]
+pub struct CollectVecError { _p: () }
+
+impl<T: Buf> FromBufStream<T> for Vec<u8> {
+    type Builder = Vec<u8>;
+    type Error = CollectVecError;
+
+    fn builder(_hint: &SizeHint) -> Vec<u8> {
+        Vec::new()
+    }
+
+    fn extend(builder: &mut Self, buf: &mut T, hint: &SizeHint) -> Result<(), Self::Error> {
+        let lower = hint.lower();
+
+        // If the lower bound is greater than `usize::MAX` then we have a
+        // problem
+        if lower > usize::MAX as u64 {
+            return Err(CollectVecError { _p: () });
+        }
+
+        let mut reserve = lower as usize;
+
+        // If `upper` is set, use this value if it is less than or equal to 64.
+        // This only really impacts the first iteration.
+        match hint.upper() {
+            Some(upper) if upper <= 64 => {
+                reserve = upper as usize;
+            }
+            _ => {},
+        }
+
+        // hint.lower() represents the minimum amount of data that will be
+        // received *after* this function call. We reserve this amount on top of
+        // the amount of data in `buf`.
+        reserve = match reserve.checked_add(buf.remaining()) {
+            Some(n) => n,
+            None => return Err(CollectVecError { _p: () }),
+        };
+
+        // Always reserve 64 bytes the first time, unless `upper` is set and is
+        // less than 64.
+        if builder.is_empty() {
+            reserve = reserve.max(match hint.upper() {
+                Some(upper) if upper < 64 => upper as usize,
+                _ => 64,
+            });
+        }
+
+        // Make sure overflow won't happen when reserving
+        if reserve.checked_add(builder.len()).is_none() {
+            return Err(CollectVecError { _p: () });
+        }
+
+        // Reserve space
+        builder.reserve(reserve);
+
+        // Copy the data
+        builder.put(buf);
+
+        Ok(())
+    }
+
+    fn build(builder: Self) -> Result<Self, Self::Error> {
+        Ok(builder)
+    }
+}

tokio-buf/src/buf_stream/limit.rs

@@ -0,0 +1,92 @@
+use super::{BufStream, SizeHint};
+
+use bytes::Buf;
+use futures::Poll;
+
+/// Limits the stream to a maximum amount of data.
+#[derive(Debug)]
+pub struct Limit<T> {
+    stream: T,
+    remaining: u64,
+}
+
+/// Errors returned from `Limit`.
+#[derive(Debug)]
+pub struct LimitError<T> {
+    /// When `None`, limit was reached
+    inner: Option<T>,
+}
+
+impl<T> Limit<T> {
+    pub(crate) fn new(stream: T, amount: u64) -> Limit<T> {
+        Limit {
+            stream,
+            remaining: amount,
+        }
+    }
+}
+
+impl<T> BufStream for Limit<T>
+where
+    T: BufStream,
+{
+    type Item = T::Item;
+    type Error = LimitError<T::Error>;
+
+    fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
+        use futures::Async::Ready;
+
+        if self.stream.size_hint().lower() > self.remaining {
+            return Err(LimitError { inner: None });
+        }
+
+        let res = self.stream.poll_buf()
+            .map_err(|err| {
+                LimitError { inner: Some(err) }
+            });
+
+        match res {
+            Ok(Ready(Some(ref buf))) => {
+                if buf.remaining() as u64 > self.remaining {
+                    self.remaining = 0;
+                    return Err(LimitError { inner: None });
+                }
+
+                self.remaining -= buf.remaining() as u64;
+            }
+            _ => {}
+        }
+
+        res
+    }
+
+    fn size_hint(&self) -> SizeHint {
+        let mut hint = self.stream.size_hint();
+
+        let upper = hint.upper()
+            .map(|upper| upper.min(self.remaining))
+            .unwrap_or(self.remaining);
+
+        hint.set_upper(upper);
+        hint
+    }
+
+    fn consume_hint(&mut self, amount: usize) {
+        // TODO: Should this be capped by `self.remaining`?
+        self.stream.consume_hint(amount)
+    }
+}
+
+// ===== impl LimitError =====
+
+impl<T> LimitError<T> {
+    /// Returns `true` if the error was caused by polling the stream.
+    pub fn is_stream_err(&self) -> bool {
+        self.inner.is_some()
+    }
+
+    /// Returns `true` if the stream reached its limit.
+    pub fn is_limit_err(&self) -> bool {
+        self.inner.is_none()
+    }
+}

tokio-buf/src/buf_stream/mod.rs

@@ -0,0 +1,163 @@
+//! Types and utilities for working with `BufStream`.
+
+mod bytes;
+mod chain;
+mod collect;
+pub mod errors;
+mod from;
+mod limit;
+mod size_hint;
+mod str;
+
+pub use self::chain::Chain;
+pub use self::collect::Collect;
+pub use self::from::FromBufStream;
+pub use self::limit::Limit;
+pub use self::size_hint::SizeHint;
+
+use bytes::Buf;
+use futures::Poll;
+
+/// An asynchronous stream of bytes.
+///
+/// `BufStream` asynchronously yields values implementing `Buf`, i.e. byte
+/// buffers.
+pub trait BufStream {
+    /// Values yielded by the `BufStream`.
+    ///
+    /// Each item is a sequence of bytes representing a chunk of the total
+    /// `ByteStream`.
+    type Item: Buf;
+
+    /// The error type this `BufStream` might generate.
+    type Error;
+
+    /// Attempt to pull out the next buffer of this stream, registering the
+    /// current task for wakeup if the value is not yet available, and returning
+    /// `None` if the stream is exhausted.
+    ///
+    /// # Return value
+    ///
+    /// There are several possible return values, each indicating a distinct
+    /// stream state:
+    ///
+    /// - `Ok(Async::NotReady)` means that this stream's next value is not ready
+    /// yet. Implementations will ensure that the current task will be notified
+    /// when the next value may be ready.
+    ///
+    /// - `Ok(Async::Ready(Some(buf)))` means that the stream has successfully
+    /// produced a value, `buf`, and may produce further values on subsequent
+    /// `poll_buf` calls.
+    ///
+    /// - `Ok(Async::Ready(None))` means that the stream has terminated, and
+    /// `poll_buf` should not be invoked again.
+    ///
+    /// # Panics
+    ///
+    /// Once a stream is finished, i.e. `Ready(None)` has been returned, further
+    /// calls to `poll_buf` may result in a panic or other "bad behavior".
+    fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error>;
+
+    /// Returns the bounds on the remaining length of the stream.
+    ///
+    /// The size hint allows the caller to perform certain optimizations that
+    /// are dependent on the byte stream size. For example, `collect` uses the
+    /// size hint to pre-allocate enough capacity to store the entirety of the
+    /// data received from the byte stream.
+    ///
+    /// When `SizeHint::upper()` returns `Some` with a value equal to
+    /// `SizeHint::lower()`, this represents the exact number of bytes that will
+    /// be yielded by the `BufStream`.
+    ///
+    /// # Implementation notes
+    ///
+    /// While not enforced, implementations are expected to respect the values
+    /// returned from `SizeHint`. Any deviation is considered an implementation
+    /// bug. Consumers may rely on correctness in order to use the value as part
+    /// of protocol impelmentations. For example, an HTTP library may use the
+    /// size hint to set the `content-length` header.
+    ///
+    /// However, `size_hint` must not be trusted to omit bounds checks in unsafe
+    /// code. An incorrect implementation of `size_hint()` must not lead to
+    /// memory safety violations.
+    fn size_hint(&self) -> SizeHint {
+        SizeHint::default()
+    }
+
+    /// Indicates to the `BufStream` how much data the consumer is currently
+    /// able to process.
+    ///
+    /// The consume hint allows the stream to perform certain optimizations that
+    /// are dependent on the consumer's readiness. For example, the consume hint
+    /// may be used to request a remote peer to start sending up to `amount`
+    /// data.
+    ///
+    /// Calling `consume_hint` is not a requirement. If `consume_hint` is never
+    /// called, the stream should assume a default behavior. When `consume_hint`
+    /// is called, the stream should make a best effort to honor by the request.
+    ///
+    /// `amount` represents the number of bytes that the caller would like to
+    /// receive at the time the function is called. For example, if
+    /// `consume_hint` is called with 20, the consumer requests 20 bytes. The
+    /// stream may yield less than that. If the next call to `poll_buf` returns
+    /// 5 bytes, the consumer still has 15 bytes requested. At this point,
+    /// invoking `consume_hint` again with 20 resets the amount requested back
+    /// to 20 bytes.
+    ///
+    /// Calling `consume_hint` with 0 as the argument informs the stream that
+    /// the caller does not intend to call `poll_buf`. If `poll_buf` **is**
+    /// called, the stream may, but is not obligated to, return `NotReady` even
+    /// if it could produce data at that point. If it chooses to return
+    /// `NotReady`, when `consume_hint` is called with a non-zero argument, the
+    /// task must be notified in order to respect the `poll_buf` contract.
+    fn consume_hint(&mut self, amount: usize) {
+        // By default, this function does nothing
+        drop(amount);
+    }
+
+    /// Takes two buf streams and creates a new buf stream over both in
+    /// sequence.
+    ///
+    /// `chain()` returns a new `BufStream` value which will first yield all
+    /// data from `self` then all data from `other`.
+    ///
+    /// In other words, it links two buf streams together, in a chain.
+    fn chain<T>(self, other: T) -> Chain<Self, T>
+    where
+        Self: Sized,
+        T: BufStream<Error = Self::Error>,
+    {
+        Chain::new(self, other)
+    }
+
+    /// Consumes all data from `self`, storing it in byte storage of type `T`.
+    ///
+    /// `collect()` returns a future that buffers all data yielded from `self`
+    /// into storage of type of `T`. The future completes once `self` yield
+    /// `None`, returning the buffered data.
+    ///
+    /// The collect future will yield an error if `self` yields an error or if
+    /// the collect operation errors. The collect error cases are dependent on
+    /// the target storage type.
+    fn collect<T>(self) -> Collect<Self, T>
+    where
+        Self: Sized,
+        T: FromBufStream<Self::Item>,
+    {
+        Collect::new(self)
+    }
+
+    /// Limit the number of bytes that the stream can yield.
+    ///
+    /// `limit()` returns a new `BufStream` value which yields all the data from
+    /// `self` while ensuring that at most `amount` bytes are yielded.
+    ///
+    /// If `self` can yield greater than `amount` bytes, the returned stream
+    /// will yield an error.
+    fn limit(self, amount: u64) -> Limit<Self>
+    where
+        Self: Sized,
+    {
+        Limit::new(self, amount)
+    }
+}

tokio-buf/src/buf_stream/size_hint.rs

@@ -0,0 +1,56 @@
+use std::u64;
+
+/// A `BufStream` size hint
+///
+/// The default implementation returns:
+///
+/// * 0 for `available`
+/// * 0 for `lower`
+/// * `None` for `upper`.
+#[derive(Debug, Default, Clone)]
+pub struct SizeHint {
+    lower: u64,
+    upper: Option<u64>,
+}
+
+impl SizeHint {
+    /// Returns a new `SizeHint` with default values
+    pub fn new() -> SizeHint {
+        SizeHint::default()
+    }
+
+    /// Returns the lower bound of data that the `BufStream` will yield before
+    /// completing.
+    pub fn lower(&self) -> u64 {
+        self.lower
+    }
+
+    /// Set the value of the `lower` hint.
+    ///
+    /// # Panics
+    ///
+    /// The function panics if `value` is less than `upper`.
+    pub fn set_lower(&mut self, value: u64) {
+        assert!(value <= self.upper.unwrap_or(u64::MAX));
+        self.lower = value;
+    }
+
+    /// Returns the upper bound of data the `BufStream` will yield before
+    /// completing, or `None` if the value is unknown.
+    pub fn upper(&self) -> Option<u64> {
+        self.upper
+    }
+
+    /// Set the value of the `upper` hint value.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if `value` is less than `lower`.
+    pub fn set_upper(&mut self, value: u64) {
+        // There is no need to check `available` as that is guaranteed to be
+        // less than or equal to `lower`.
+        assert!(value >= self.lower, "`value` is less than than `lower`");
+
+        self.upper = Some(value);
+    }
+}

tokio-buf/src/buf_stream/str.rs

@@ -0,0 +1,39 @@
+use BufStream;
+use buf_stream::errors::internal::Never;
+
+use futures::Poll;
+
+use std::io;
+use std::mem;
+
+impl BufStream for String {
+    type Item = io::Cursor<Vec<u8>>;
+    type Error = Never;
+
+    fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
+        if self.is_empty() {
+            return Ok(None.into());
+        }
+
+        let bytes = mem::replace(self, Default::default()).into_bytes();
+        let buf = io::Cursor::new(bytes);
+
+        Ok(Some(buf).into())
+    }
+}
+
+impl BufStream for &'static str {
+    type Item = io::Cursor<&'static [u8]>;
+    type Error = Never;
+
+    fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
+        if self.is_empty() {
+            return Ok(None.into());
+        }
+
+        let bytes = mem::replace(self, Default::default()).as_bytes();
+        let buf = io::Cursor::new(bytes);
+
+        Ok(Some(buf).into())
+    }
+}

tokio-buf/src/lib.rs

@@ -0,0 +1,20 @@
+#![doc(html_root_url = "https://docs.rs/tokio-buf/0.1.0")]
+#![deny(missing_docs, missing_debug_implementations)]
+#![cfg_attr(test, deny(warnings))]
+
+//! Asynchronous stream of bytes.
+//!
+//! This crate contains the `BufStream` trait and a number of combinators for
+//! this trait. The trait is similar to `Stream` in the `futures` library, but
+//! instead of yielding arbitrary values, it only yields types that implement
+//! `Buf` (i.e, byte collections).
+
+extern crate bytes;
+extern crate either;
+#[macro_use]
+extern crate futures;
+
+pub mod buf_stream;
+
+#[doc(inline)]
+pub use buf_stream::BufStream;

tokio-buf/tests/buf_stream.rs

@@ -0,0 +1,329 @@
+extern crate tokio_buf;
+extern crate bytes;
+extern crate futures;
+
+use tokio_buf::buf_stream::{BufStream, SizeHint};
+use bytes::Buf;
+use futures::{Future, Poll};
+use futures::Async::*;
+
+use std::collections::VecDeque;
+use std::io::Cursor;
+
+macro_rules! assert_buf_eq {
+    ($actual:expr, $expect:expr) => {{
+        match $actual {
+            Ok(Ready(Some(val))) => {
+                assert_eq!(val.remaining(), val.bytes().len());
+                assert_eq!(val.bytes(), $expect.as_bytes());
+            }
+            Ok(Ready(None)) => panic!("expected value; BufStream yielded None"),
+            Ok(NotReady) => panic!("expected value; BufStream is not ready"),
+            Err(e) => panic!("expected value; got error = {:?}", e),
+        }
+    }};
+}
+
+macro_rules! assert_none {
+    ($actual:expr) => {
+        match $actual {
+            Ok(Ready(None)) => {}
+            actual => panic!("expected None; actual = {:?}", actual),
+        }
+    }
+}
+
+macro_rules! assert_not_ready {
+    ($actual:expr) => {
+        match $actual {
+            Ok(NotReady) => {}
+            actual => panic!("expected NotReady; actual = {:?}", actual),
+        }
+    }
+}
+
+// ===== test `SizeHint` =====
+
+#[test]
+fn size_hint() {
+    let hint = SizeHint::new();
+    assert_eq!(hint.lower(), 0);
+    assert!(hint.upper().is_none());
+
+    let mut hint = SizeHint::new();
+    hint.set_lower(100);
+    assert_eq!(hint.lower(), 100);
+    assert!(hint.upper().is_none());
+
+    let mut hint = SizeHint::new();
+    hint.set_upper(200);
+    assert_eq!(hint.lower(), 0);
+    assert_eq!(hint.upper(), Some(200));
+
+    let mut hint = SizeHint::new();
+    hint.set_lower(100);
+    hint.set_upper(100);
+    assert_eq!(hint.lower(), 100);
+    assert_eq!(hint.upper(), Some(100));
+}
+
+#[test]
+#[should_panic]
+fn size_hint_lower_bigger_than_upper() {
+    let mut hint = SizeHint::new();
+    hint.set_upper(100);
+    hint.set_lower(200);
+}
+
+#[test]
+#[should_panic]
+fn size_hint_upper_less_than_lower() {
+    let mut hint = SizeHint::new();
+    hint.set_lower(200);
+    hint.set_upper(100);
+}
+
+// ===== test `chain()` =====
+
+#[test]
+fn chain() {
+    // Chain one with one
+    //
+    let mut bs = one("hello").chain(one("world"));
+
+    assert_buf_eq!(bs.poll_buf(), "hello");
+    assert_buf_eq!(bs.poll_buf(), "world");
+    assert_none!(bs.poll_buf());
+
+    // Chain multi with multi
+    let mut bs = list(&["foo", "bar"])
+        .chain(list(&["baz", "bok"]));
+
+    assert_buf_eq!(bs.poll_buf(), "foo");
+    assert_buf_eq!(bs.poll_buf(), "bar");
+    assert_buf_eq!(bs.poll_buf(), "baz");
+    assert_buf_eq!(bs.poll_buf(), "bok");
+    assert_none!(bs.poll_buf());
+
+    // Chain includes a not ready call
+    //
+    let mut bs = new_mock(&[
+        Ok(Ready("foo")),
+        Ok(NotReady),
+        Ok(Ready("bar"))
+    ]).chain(one("baz"));
+
+    assert_buf_eq!(bs.poll_buf(), "foo");
+    assert_not_ready!(bs.poll_buf());
+    assert_buf_eq!(bs.poll_buf(), "bar");
+    assert_buf_eq!(bs.poll_buf(), "baz");
+    assert_none!(bs.poll_buf());
+}
+
+// ===== Test `collect()` =====
+
+#[test]
+fn collect_vec() {
+    // While unfortunate, this test makes some assumptions on vec's resizing
+    // behavior.
+    //
+    // Collect one
+    //
+    let bs = one("hello world");
+
+    let vec: Vec<u8> = bs.collect()
+        .wait().unwrap();
+
+    assert_eq!(vec, b"hello world");
+    assert_eq!(vec.capacity(), 64);
+
+    // Collect one, with size hint
+    //
+    let mut bs = one("hello world");
+    bs.size_hint.set_lower(11);
+
+    let vec: Vec<u8> = bs.collect()
+        .wait().unwrap();
+
+    assert_eq!(vec, b"hello world");
+    assert_eq!(vec.capacity(), 64);
+
+    // Collect one, with size hint
+    //
+    let mut bs = one("hello world");
+    bs.size_hint.set_lower(10);
+
+    let vec: Vec<u8> = bs.collect()
+        .wait().unwrap();
+
+    assert_eq!(vec, b"hello world");
+    assert_eq!(vec.capacity(), 64);
+
+    // Collect many
+    //
+    let bs = list(&["hello", " ", "world", ", one two three"]);
+
+    let vec: Vec<u8> = bs.collect()
+        .wait().unwrap();
+
+    assert_eq!(vec, b"hello world, one two three");
+}
+
+// ===== Test limit() =====
+
+#[test]
+fn limit() {
+    // Not limited
+
+    let res = one("hello world")
+        .limit(100)
+        .collect::<Vec<_>>()
+        .wait().unwrap();
+
+    assert_eq!(res, b"hello world");
+
+    let res = list(&["hello", " ", "world"])
+        .limit(100)
+        .collect::<Vec<_>>()
+        .wait().unwrap();
+
+    assert_eq!(res, b"hello world");
+
+    let res = list(&["hello", " ", "world"])
+        .limit(11)
+        .collect::<Vec<_>>()
+        .wait().unwrap();
+
+    assert_eq!(res, b"hello world");
+
+    // Limited
+
+    let res = one("hello world")
+        .limit(5)
+        .collect::<Vec<_>>()
+        .wait();
+
+    assert!(res.is_err());
+
+    let res = one("hello world")
+        .limit(10)
+        .collect::<Vec<_>>()
+        .wait();
+
+    assert!(res.is_err());
+
+    let mut bs = list(&["hello", " ", "world"])
+        .limit(9);
+
+    assert_buf_eq!(bs.poll_buf(), "hello");
+    assert_buf_eq!(bs.poll_buf(), " ");
+    assert!(bs.poll_buf().is_err());
+
+    let mut bs = list(&["hello", " ", "world"]);
+    bs.size_hint.set_lower(11);
+    let mut bs = bs.limit(9);
+
+    assert!(bs.poll_buf().is_err());
+}
+
+// ===== BufStream impelmentations for misc types =====
+
+#[test]
+fn str_buf_stream() {
+    let mut bs = "hello world".to_string();
+    assert_buf_eq!(bs.poll_buf(), "hello world");
+    assert!(bs.is_empty());
+    assert_none!(bs.poll_buf());
+
+    let mut bs = "hello world";
+    assert_buf_eq!(bs.poll_buf(), "hello world");
+    assert!(bs.is_empty());
+    assert_none!(bs.poll_buf());
+}
+
+// ===== Test utils =====
+
+fn one(buf: &'static str) -> Mock {
+    list(&[buf])
+}
+
+fn list(bufs: &[&'static str]) -> Mock {
+    let mut polls = VecDeque::new();
+
+    for &buf in bufs {
+        polls.push_back(Ok(Ready(buf.as_bytes())));
+    }
+
+    Mock {
+        polls,
+        size_hint: SizeHint::default(),
+    }
+}
+
+fn new_mock(values: &[Poll<&'static str, ()>]) -> Mock {
+    let mut polls = VecDeque::new();
+
+    for &v in values {
+        polls.push_back(match v {
+            Ok(Ready(v)) => Ok(Ready(v.as_bytes())),
+            Ok(NotReady) => Ok(NotReady),
+            Err(e) => Err(e),
+        });
+    }
+
+    Mock {
+        polls,
+        size_hint: SizeHint::default(),
+    }
+}
+
+#[derive(Debug)]
+struct Mock {
+    polls: VecDeque<Poll<&'static [u8], ()>>,
+    size_hint: SizeHint,
+}
+
+#[derive(Debug)]
+struct MockBuf {
+    data: Cursor<&'static [u8]>,
+}
+
+impl BufStream for Mock {
+    type Item = MockBuf;
+    type Error = ();
+
+    fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
+        match self.polls.pop_front() {
+            Some(Ok(Ready(value))) => Ok(Ready(Some(MockBuf::new(value)))),
+            Some(Ok(NotReady)) => Ok(NotReady),
+            Some(Err(e)) => Err(e),
+            None => Ok(Ready(None)),
+        }
+    }
+
+    fn size_hint(&self) -> SizeHint {
+        self.size_hint.clone()
+    }
+}
+
+impl MockBuf {
+    fn new(data: &'static [u8]) -> MockBuf {
+        MockBuf {
+            data: Cursor::new(data),
+        }
+    }
+}
+
+impl Buf for MockBuf {
+    fn remaining(&self) -> usize {
+        self.data.remaining()
+    }
+
+    fn bytes(&self) -> &[u8] {
+        self.data.bytes()
+    }
+
+    fn advance(&mut self, cnt: usize) {
+        self.data.advance(cnt)
+    }
+}

tokio-channel/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "tokio-channel"
+
+# When releasing to crates.io:
+# - Update html_root_url.
+# - Update CHANGELOG.md.
+# - Create "v0.1.x" git tag.
+version = "0.1.0"
+authors = ["Carl Lerche <[email protected]>"]
+license = "MIT"
+repository = "https://github.com/tokio-rs/tokio"
+homepage = "https://tokio.rs"
+documentation = "https://docs.rs/tokio-channel/0.1.0"
+description = """
+Channels for asynchronous communication using Tokio.
+"""
+categories = ["asynchronous"]
+
+[dependencies]
+futures = "0.1.23"

tokio-channel/LICENSE

@@ -0,0 +1,51 @@
+Copyright (c) 2018 Tokio Contributors
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+
+Copyright (c) 2016 futures-rs Contributors
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

tokio-channel/src/lib.rs

@@ -0,0 +1,14 @@
+#![doc(html_root_url = "https://docs.rs/tokio-channel/0.1.0")]
+#![deny(missing_docs, warnings, missing_debug_implementations)]
+
+//! Asynchronous channels.
+//!
+//! This crate provides channels that can be used to communicate between
+//! asynchronous tasks.
+
+extern crate futures;
+
+pub mod mpsc;
+pub mod oneshot;
+
+mod lock;

tokio-channel/src/lock.rs

@@ -0,0 +1,105 @@
+//! A "mutex" which only supports `try_lock`
+//!
+//! As a futures library the eventual call to an event loop should be the only
+//! thing that ever blocks, so this is assisted with a fast user-space
+//! implementation of a lock that can only have a `try_lock` operation.
+
+use std::cell::UnsafeCell;
+use std::ops::{Deref, DerefMut};
+use std::sync::atomic::Ordering::SeqCst;
+use std::sync::atomic::AtomicBool;
+
+/// A "mutex" around a value, similar to `std::sync::Mutex<T>`.
+///
+/// This lock only supports the `try_lock` operation, however, and does not
+/// implement poisoning.
+#[derive(Debug)]
+pub struct Lock<T> {
+    locked: AtomicBool,
+    data: UnsafeCell<T>,
+}
+
+/// Sentinel representing an acquired lock through which the data can be
+/// accessed.
+pub struct TryLock<'a, T: 'a> {
+    __ptr: &'a Lock<T>,
+}
+
+// The `Lock` structure is basically just a `Mutex<T>`, and these two impls are
+// intended to mirror the standard library's corresponding impls for `Mutex<T>`.
+//
+// If a `T` is sendable across threads, so is the lock, and `T` must be sendable
+// across threads to be `Sync` because it allows mutable access from multiple
+// threads.
+unsafe impl<T: Send> Send for Lock<T> {}
+unsafe impl<T: Send> Sync for Lock<T> {}
+
+impl<T> Lock<T> {
+    /// Creates a new lock around the given value.
+    pub fn new(t: T) -> Lock<T> {
+        Lock {
+            locked: AtomicBool::new(false),
+            data: UnsafeCell::new(t),
+        }
+    }
+
+    /// Attempts to acquire this lock, returning whether the lock was acquired or
+    /// not.
+    ///
+    /// If `Some` is returned then the data this lock protects can be accessed
+    /// through the sentinel. This sentinel allows both mutable and immutable
+    /// access.
+    ///
+    /// If `None` is returned then the lock is already locked, either elsewhere
+    /// on this thread or on another thread.
+    pub fn try_lock(&self) -> Option<TryLock<T>> {
+        if !self.locked.swap(true, SeqCst) {
+            Some(TryLock { __ptr: self })
+        } else {
+            None
+        }
+    }
+}
+
+impl<'a, T> Deref for TryLock<'a, T> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        // The existence of `TryLock` represents that we own the lock, so we
+        // can safely access the data here.
+        unsafe { &*self.__ptr.data.get() }
+    }
+}
+
+impl<'a, T> DerefMut for TryLock<'a, T> {
+    fn deref_mut(&mut self) -> &mut T {
+        // The existence of `TryLock` represents that we own the lock, so we
+        // can safely access the data here.
+        //
+        // Additionally, we're the *only* `TryLock` in existence so mutable
+        // access should be ok.
+        unsafe { &mut *self.__ptr.data.get() }
+    }
+}
+
+impl<'a, T> Drop for TryLock<'a, T> {
+    fn drop(&mut self) {
+        self.__ptr.locked.store(false, SeqCst);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Lock;
+
+    #[test]
+    fn smoke() {
+        let a = Lock::new(1);
+        let mut a1 = a.try_lock().unwrap();
+        assert!(a.try_lock().is_none());
+        assert_eq!(*a1, 1);
+        *a1 = 2;
+        drop(a1);
+        assert_eq!(*a.try_lock().unwrap(), 2);
+        assert_eq!(*a.try_lock().unwrap(), 2);
+    }
+}

tokio-channel/src/mpsc/mod.rs

@@ -0,0 +1,989 @@
+//! A multi-producer, single-consumer, futures-aware, FIFO queue with back pressure.
+//!
+//! A channel can be used as a communication primitive between tasks running on
+//! `futures-rs` executors. Channel creation provides `Receiver` and `Sender`
+//! handles. `Receiver` implements `Stream` and allows a task to read values
+//! out of the channel. If there is no message to read from the channel, the
+//! current task will be notified when a new value is sent. `Sender` implements
+//! the `Sink` trait and allows a task to send messages into the channel. If
+//! the channel is at capacity, then send will be rejected and the task will be
+//! notified when additional capacity is available.
+//!
+//! # Disconnection
+//!
+//! When all `Sender` handles have been dropped, it is no longer possible to
+//! send values into the channel. This is considered the termination event of
+//! the stream. As such, `Sender::poll` will return `Ok(Ready(None))`.
+//!
+//! If the receiver handle is dropped, then messages can no longer be read out
+//! of the channel. In this case, a `send` will result in an error.
+//!
+//! # Clean Shutdown
+//!
+//! If the `Receiver` is simply dropped, then it is possible for there to be
+//! messages still in the channel that will not be processed. As such, it is
+//! usually desirable to perform a "clean" shutdown. To do this, the receiver
+//! will first call `close`, which will prevent any further messages to be sent
+//! into the channel. Then, the receiver consumes the channel to completion, at
+//! which point the receiver can be dropped.
+
+// At the core, the channel uses an atomic FIFO queue for message passing. This
+// queue is used as the primary coordination primitive. In order to enforce
+// capacity limits and handle back pressure, a secondary FIFO queue is used to
+// send parked task handles.
+//
+// The general idea is that the channel is created with a `buffer` size of `n`.
+// The channel capacity is `n + num-senders`. Each sender gets one "guaranteed"
+// slot to hold a message. This allows `Sender` to know for a fact that a send
+// will succeed *before* starting to do the actual work of sending the value.
+// Since most of this work is lock-free, once the work starts, it is impossible
+// to safely revert.
+//
+// If the sender is unable to process a send operation, then the current
+// task is parked and the handle is sent on the parked task queue.
+//
+// Note that the implementation guarantees that the channel capacity will never
+// exceed the configured limit, however there is no *strict* guarantee that the
+// receiver will wake up a parked task *immediately* when a slot becomes
+// available. However, it will almost always unpark a task when a slot becomes
+// available and it is *guaranteed* that a sender will be unparked when the
+// message that caused the sender to become parked is read out of the channel.
+//
+// The steps for sending a message are roughly:
+//
+// 1) Increment the channel message count
+// 2) If the channel is at capacity, push the task handle onto the wait queue
+// 3) Push the message onto the message queue.
+//
+// The steps for receiving a message are roughly:
+//
+// 1) Pop a message from the message queue
+// 2) Pop a task handle from the wait queue
+// 3) Decrement the channel message count.
+//
+// It's important for the order of operations on lock-free structures to happen
+// in reverse order between the sender and receiver. This makes the message
+// queue the primary coordination structure and establishes the necessary
+// happens-before semantics required for the acquire / release semantics used
+// by the queue structure.
+
+
+
+use mpsc::queue::{Queue, PopResult};
+
+use futures::task::{self, Task};
+use futures::{Async, AsyncSink, Poll, StartSend, Sink, Stream};
+
+use std::fmt;
+use std::error::Error;
+use std::any::Any;
+use std::sync::atomic::AtomicUsize;
+use std::sync::atomic::Ordering::SeqCst;
+use std::sync::{Arc, Mutex};
+use std::thread;
+use std::usize;
+
+mod queue;
+
+/// The transmission end of a channel which is used to send values.
+///
+/// This is created by the `channel` method.
+#[derive(Debug)]
+pub struct Sender<T> {
+    // Channel state shared between the sender and receiver.
+    inner: Arc<Inner<T>>,
+
+    // Handle to the task that is blocked on this sender. This handle is sent
+    // to the receiver half in order to be notified when the sender becomes
+    // unblocked.
+    sender_task: Arc<Mutex<SenderTask>>,
+
+    // True if the sender might be blocked. This is an optimization to avoid
+    // having to lock the mutex most of the time.
+    maybe_parked: bool,
+}
+
+/// The transmission end of a channel which is used to send values.
+///
+/// This is created by the `unbounded` method.
+#[derive(Debug)]
+pub struct UnboundedSender<T>(Sender<T>);
+
+trait AssertKinds: Send + Sync + Clone {}
+impl AssertKinds for UnboundedSender<u32> {}
+
+
+/// The receiving end of a channel which implements the `Stream` trait.
+///
+/// This is a concrete implementation of a stream which can be used to represent
+/// a stream of values being computed elsewhere. This is created by the
+/// `channel` method.
+#[derive(Debug)]
+pub struct Receiver<T> {
+    inner: Arc<Inner<T>>,
+}
+
+/// Error type for sending, used when the receiving end of a channel is
+/// dropped
+#[derive(Clone, PartialEq, Eq)]
+pub struct SendError<T>(T);
+
+/// Error type returned from `try_send`
+#[derive(Clone, PartialEq, Eq)]
+pub struct TrySendError<T> {
+    kind: TrySendErrorKind<T>,
+}
+
+#[derive(Clone, PartialEq, Eq)]
+enum TrySendErrorKind<T> {
+    Full(T),
+    Disconnected(T),
+}
+
+impl<T> fmt::Debug for SendError<T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        fmt.debug_tuple("SendError")
+            .field(&"...")
+            .finish()
+    }
+}
+
+impl<T> fmt::Display for SendError<T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "send failed because receiver is gone")
+    }
+}
+
+impl<T: Any> Error for SendError<T>
+{
+    fn description(&self) -> &str {
+        "send failed because receiver is gone"
+    }
+}
+
+impl<T> SendError<T> {
+    /// Returns the message that was attempted to be sent but failed.
+    pub fn into_inner(self) -> T {
+        self.0
+    }
+}
+
+impl<T> fmt::Debug for TrySendError<T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        fmt.debug_tuple("TrySendError")
+            .field(&"...")
+            .finish()
+    }
+}
+
+impl<T> fmt::Display for TrySendError<T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        if self.is_full() {
+            write!(fmt, "send failed because channel is full")
+        } else {
+            write!(fmt, "send failed because receiver is gone")
+        }
+    }
+}
+
+impl<T: Any> Error for TrySendError<T> {
+    fn description(&self) -> &str {
+        if self.is_full() {
+            "send failed because channel is full"
+        } else {
+            "send failed because receiver is gone"
+        }
+    }
+}
+
+impl<T> TrySendError<T> {
+    /// Returns true if this error is a result of the channel being full
+    pub fn is_full(&self) -> bool {
+        use self::TrySendErrorKind::*;
+
+        match self.kind {
+            Full(_) => true,
+            _ => false,
+        }
+    }
+
+    /// Returns true if this error is a result of the receiver being dropped
+    pub fn is_disconnected(&self) -> bool {
+        use self::TrySendErrorKind::*;
+
+        match self.kind {
+            Disconnected(_) => true,
+            _ => false,
+        }
+    }
+
+    /// Returns the message that was attempted to be sent but failed.
+    pub fn into_inner(self) -> T {
+        use self::TrySendErrorKind::*;
+
+        match self.kind {
+            Full(v) | Disconnected(v) => v,
+        }
+    }
+}
+
+#[derive(Debug)]
+struct Inner<T> {
+    // Max buffer size of the channel. If `None` then the channel is unbounded.
+    buffer: Option<usize>,
+
+    // Internal channel state. Consists of the number of messages stored in the
+    // channel as well as a flag signalling that the channel is closed.
+    state: AtomicUsize,
+
+    // Atomic, FIFO queue used to send messages to the receiver
+    message_queue: Queue<Option<T>>,
+
+    // Atomic, FIFO queue used to send parked task handles to the receiver.
+    parked_queue: Queue<Arc<Mutex<SenderTask>>>,
+
+    // Number of senders in existence
+    num_senders: AtomicUsize,
+
+    // Handle to the receiver's task.
+    recv_task: Mutex<ReceiverTask>,
+}
+
+// Struct representation of `Inner::state`.
+#[derive(Debug, Clone, Copy)]
+struct State {
+    // `true` when the channel is open
+    is_open: bool,
+
+    // Number of messages in the channel
+    num_messages: usize,
+}
+
+#[derive(Debug)]
+struct ReceiverTask {
+    unparked: bool,
+    task: Option<Task>,
+}
+
+// Returned from Receiver::try_park()
+enum TryPark {
+    Parked,
+    Closed,
+    NotEmpty,
+}
+
+// The `is_open` flag is stored in the left-most bit of `Inner::state`
+const OPEN_MASK: usize = usize::MAX - (usize::MAX >> 1);
+
+// When a new channel is created, it is created in the open state with no
+// pending messages.
+const INIT_STATE: usize = OPEN_MASK;
+
+// The maximum number of messages that a channel can track is `usize::MAX >> 1`
+const MAX_CAPACITY: usize = !(OPEN_MASK);
+
+// The maximum requested buffer size must be less than the maximum capacity of
+// a channel. This is because each sender gets a guaranteed slot.
+const MAX_BUFFER: usize = MAX_CAPACITY >> 1;
+
+// Sent to the consumer to wake up blocked producers
+#[derive(Debug)]
+struct SenderTask {
+    task: Option<Task>,
+    is_parked: bool,
+}
+
+impl SenderTask {
+    fn new() -> Self {
+        SenderTask {
+            task: None,
+            is_parked: false,
+        }
+    }
+
+    fn notify(&mut self) {
+        self.is_parked = false;
+
+        if let Some(task) = self.task.take() {
+            task.notify();
+        }
+    }
+}
+
+/// Creates an in-memory channel implementation of the `Stream` trait with
+/// bounded capacity.
+///
+/// This method creates a concrete implementation of the `Stream` trait which
+/// can be used to send values across threads in a streaming fashion. This
+/// channel is unique in that it implements back pressure to ensure that the
+/// sender never outpaces the receiver. The channel capacity is equal to
+/// `buffer + num-senders`. In other words, each sender gets a guaranteed slot
+/// in the channel capacity, and on top of that there are `buffer` "first come,
+/// first serve" slots available to all senders.
+///
+/// The `Receiver` returned implements the `Stream` trait and has access to any
+/// number of the associated combinators for transforming the result.
+pub fn channel<T>(buffer: usize) -> (Sender<T>, Receiver<T>) {
+    // Check that the requested buffer size does not exceed the maximum buffer
+    // size permitted by the system.
+    assert!(buffer < MAX_BUFFER, "requested buffer size too large");
+    channel2(Some(buffer))
+}
+
+/// Creates an in-memory channel implementation of the `Stream` trait with
+/// unbounded capacity.
+///
+/// This method creates a concrete implementation of the `Stream` trait which
+/// can be used to send values across threads in a streaming fashion. A `send`
+/// on this channel will always succeed as long as the receive half has not
+/// been closed. If the receiver falls behind, messages will be buffered
+/// internally.
+///
+/// **Note** that the amount of available system memory is an implicit bound to
+/// the channel. Using an `unbounded` channel has the ability of causing the
+/// process to run out of memory. In this case, the process will be aborted.
+pub fn unbounded<T>() -> (UnboundedSender<T>, Receiver<T>) {
+    let (tx, rx) = channel2(None);
+    (UnboundedSender(tx), rx)
+}
+
+fn channel2<T>(buffer: Option<usize>) -> (Sender<T>, Receiver<T>) {
+    let inner = Arc::new(Inner {
+        buffer: buffer,
+        state: AtomicUsize::new(INIT_STATE),
+        message_queue: Queue::new(),
+        parked_queue: Queue::new(),
+        num_senders: AtomicUsize::new(1),
+        recv_task: Mutex::new(ReceiverTask {
+            unparked: false,
+            task: None,
+        }),
+    });
+
+    let tx = Sender {
+        inner: inner.clone(),
+        sender_task: Arc::new(Mutex::new(SenderTask::new())),
+        maybe_parked: false,
+    };
+
+    let rx = Receiver {
+        inner: inner,
+    };
+
+    (tx, rx)
+}
+
+/*
+ *
+ * ===== impl Sender =====
+ *
+ */
+
+impl<T> Sender<T> {
+    /// Attempts to send a message on this `Sender<T>` without blocking.
+    ///
+    /// This function, unlike `start_send`, is safe to call whether it's being
+    /// called on a task or not. Note that this function, however, will *not*
+    /// attempt to block the current task if the message cannot be sent.
+    ///
+    /// It is not recommended to call this function from inside of a future,
+    /// only from an external thread where you've otherwise arranged to be
+    /// notified when the channel is no longer full.
+    pub fn try_send(&mut self, msg: T) -> Result<(), TrySendError<T>> {
+        // If the sender is currently blocked, reject the message
+        if !self.poll_unparked(false).is_ready() {
+            return Err(TrySendError {
+                kind: TrySendErrorKind::Full(msg),
+            });
+        }
+
+        // The channel has capacity to accept the message, so send it
+        self.do_send(Some(msg), false)
+            .map_err(|SendError(v)| {
+                TrySendError {
+                    kind: TrySendErrorKind::Disconnected(v),
+                }
+            })
+    }
+
+    // Do the send without failing
+    // None means close
+    fn do_send(&mut self, msg: Option<T>, do_park: bool) -> Result<(), SendError<T>> {
+        // First, increment the number of messages contained by the channel.
+        // This operation will also atomically determine if the sender task
+        // should be parked.
+        //
+        // None is returned in the case that the channel has been closed by the
+        // receiver. This happens when `Receiver::close` is called or the
+        // receiver is dropped.
+        let park_self = match self.inc_num_messages(msg.is_none()) {
+            Some(park_self) => park_self,
+            None => {
+                // The receiver has closed the channel. Only abort if actually
+                // sending a message. It is important that the stream
+                // termination (None) is always sent. This technically means
+                // that it is possible for the queue to contain the following
+                // number of messages:
+                //
+                //     num-senders + buffer + 1
+                //
+                if let Some(msg) = msg {
+                    return Err(SendError(msg));
+                } else {
+                    return Ok(());
+                }
+            }
+        };
+
+        // If the channel has reached capacity, then the sender task needs to
+        // be parked. This will send the task handle on the parked task queue.
+        //
+        // However, when `do_send` is called while dropping the `Sender`,
+        // `task::current()` can't be called safely. In this case, in order to
+        // maintain internal consistency, a blank message is pushed onto the
+        // parked task queue.
+        if park_self {
+            self.park(do_park);
+        }
+
+        self.queue_push_and_signal(msg);
+
+        Ok(())
+    }
+
+    // Do the send without parking current task.
+    //
+    // To be called from unbounded sender.
+    fn do_send_nb(&self, msg: T) -> Result<(), SendError<T>> {
+        match self.inc_num_messages(false) {
+            Some(park_self) => assert!(!park_self),
+            None => return Err(SendError(msg)),
+        };
+
+        self.queue_push_and_signal(Some(msg));
+
+        Ok(())
+    }
+
+    // Push message to the queue and signal to the receiver
+    fn queue_push_and_signal(&self, msg: Option<T>) {
+        // Push the message onto the message queue
+        self.inner.message_queue.push(msg);
+
+        // Signal to the receiver that a message has been enqueued. If the
+        // receiver is parked, this will unpark the task.
+        self.signal();
+    }
+
+    // Increment the number of queued messages. Returns if the sender should
+    // block.
+    fn inc_num_messages(&self, close: bool) -> Option<bool> {
+        let mut curr = self.inner.state.load(SeqCst);
+
+        loop {
+            let mut state = decode_state(curr);
+
+            // The receiver end closed the channel.
+            if !state.is_open {
+                return None;
+            }
+
+            // This probably is never hit? Odds are the process will run out of
+            // memory first. It may be worth to return something else in this
+            // case?
+            assert!(state.num_messages < MAX_CAPACITY, "buffer space exhausted; \
+                    sending this messages would overflow the state");
+
+            state.num_messages += 1;
+
+            // The channel is closed by all sender handles being dropped.
+            if close {
+                state.is_open = false;
+            }
+
+            let next = encode_state(&state);
+            match self.inner.state.compare_exchange(curr, next, SeqCst, SeqCst) {
+                Ok(_) => {
+                    // Block if the current number of pending messages has exceeded
+                    // the configured buffer size
+                    let park_self = match self.inner.buffer {
+                        Some(buffer) => state.num_messages > buffer,
+                        None => false,
+                    };
+
+                    return Some(park_self)
+                }
+                Err(actual) => curr = actual,
+            }
+        }
+    }
+
+    // Signal to the receiver task that a message has been enqueued
+    fn signal(&self) {
+        // TODO
+        // This logic can probably be improved by guarding the lock with an
+        // atomic.
+        //
+        // Do this step first so that the lock is dropped when
+        // `unpark` is called
+        let task = {
+            let mut recv_task = self.inner.recv_task.lock().unwrap();
+
+            // If the receiver has already been unparked, then there is nothing
+            // more to do
+            if recv_task.unparked {
+                return;
+            }
+
+            // Setting this flag enables the receiving end to detect that
+            // an unpark event happened in order to avoid unnecessarily
+            // parking.
+            recv_task.unparked = true;
+            recv_task.task.take()
+        };
+
+        if let Some(task) = task {
+            task.notify();
+        }
+    }
+
+    fn park(&mut self, can_park: bool) {
+        // TODO: clean up internal state if the task::current will fail
+
+        let task = if can_park {
+            Some(task::current())
+        } else {
+            None
+        };
+
+        {
+            let mut sender = self.sender_task.lock().unwrap();
+            sender.task = task;
+            sender.is_parked = true;
+        }
+
+        // Send handle over queue
+        let t = self.sender_task.clone();
+        self.inner.parked_queue.push(t);
+
+        // Check to make sure we weren't closed after we sent our task on the
+        // queue
+        let state = decode_state(self.inner.state.load(SeqCst));
+        self.maybe_parked = state.is_open;
+    }
+
+    /// Polls the channel to determine if there is guaranteed to be capacity to send at least one
+    /// item without waiting.
+    ///
+    /// Returns `Ok(Async::Ready(_))` if there is sufficient capacity, or returns
+    /// `Ok(Async::NotReady)` if the channel is not guaranteed to have capacity. Returns
+    /// `Err(SendError(_))` if the receiver has been dropped.
+    ///
+    /// # Panics
+    ///
+    /// This method will panic if called from outside the context of a task or future.
+    pub fn poll_ready(&mut self) -> Poll<(), SendError<()>> {
+        let state = decode_state(self.inner.state.load(SeqCst));
+        if !state.is_open {
+            return Err(SendError(()));
+        }
+
+        Ok(self.poll_unparked(true))
+    }
+
+    fn poll_unparked(&mut self, do_park: bool) -> Async<()> {
+        // First check the `maybe_parked` variable. This avoids acquiring the
+        // lock in most cases
+        if self.maybe_parked {
+            // Get a lock on the task handle
+            let mut task = self.sender_task.lock().unwrap();
+
+            if !task.is_parked {
+                self.maybe_parked = false;
+                return Async::Ready(())
+            }
+
+            // At this point, an unpark request is pending, so there will be an
+            // unpark sometime in the future. We just need to make sure that
+            // the correct task will be notified.
+            //
+            // Update the task in case the `Sender` has been moved to another
+            // task
+            task.task = if do_park {
+                Some(task::current())
+            } else {
+                None
+            };
+
+            Async::NotReady
+        } else {
+            Async::Ready(())
+        }
+    }
+}
+
+impl<T> Sink for Sender<T> {
+    type SinkItem = T;
+    type SinkError = SendError<T>;
+
+    fn start_send(&mut self, msg: T) -> StartSend<T, SendError<T>> {
+        // If the sender is currently blocked, reject the message before doing
+        // any work.
+        if !self.poll_unparked(true).is_ready() {
+            return Ok(AsyncSink::NotReady(msg));
+        }
+
+        // The channel has capacity to accept the message, so send it.
+        self.do_send(Some(msg), true)?;
+
+        Ok(AsyncSink::Ready)
+    }
+
+    fn poll_complete(&mut self) -> Poll<(), SendError<T>> {
+        Ok(Async::Ready(()))
+    }
+
+    fn close(&mut self) -> Poll<(), SendError<T>> {
+        Ok(Async::Ready(()))
+    }
+}
+
+impl<T> UnboundedSender<T> {
+    /// Sends the provided message along this channel.
+    ///
+    /// This is an unbounded sender, so this function differs from `Sink::send`
+    /// by ensuring the return type reflects that the channel is always ready to
+    /// receive messages.
+    #[deprecated(note = "renamed to `unbounded_send`")]
+    #[doc(hidden)]
+    pub fn send(&self, msg: T) -> Result<(), SendError<T>> {
+        self.unbounded_send(msg)
+    }
+
+    /// Sends the provided message along this channel.
+    ///
+    /// This is an unbounded sender, so this function differs from `Sink::send`
+    /// by ensuring the return type reflects that the channel is always ready to
+    /// receive messages.
+    pub fn unbounded_send(&self, msg: T) -> Result<(), SendError<T>> {
+        self.0.do_send_nb(msg)
+    }
+}
+
+impl<T> Sink for UnboundedSender<T> {
+    type SinkItem = T;
+    type SinkError = SendError<T>;
+
+    fn start_send(&mut self, msg: T) -> StartSend<T, SendError<T>> {
+        self.0.start_send(msg)
+    }
+
+    fn poll_complete(&mut self) -> Poll<(), SendError<T>> {
+        self.0.poll_complete()
+    }
+
+    fn close(&mut self) -> Poll<(), SendError<T>> {
+        Ok(Async::Ready(()))
+    }
+}
+
+impl<'a, T> Sink for &'a UnboundedSender<T> {
+    type SinkItem = T;
+    type SinkError = SendError<T>;
+
+    fn start_send(&mut self, msg: T) -> StartSend<T, SendError<T>> {
+        self.0.do_send_nb(msg)?;
+        Ok(AsyncSink::Ready)
+    }
+
+    fn poll_complete(&mut self) -> Poll<(), SendError<T>> {
+        Ok(Async::Ready(()))
+    }
+
+    fn close(&mut self) -> Poll<(), SendError<T>> {
+        Ok(Async::Ready(()))
+    }
+}
+
+impl<T> Clone for UnboundedSender<T> {
+    fn clone(&self) -> UnboundedSender<T> {
+        UnboundedSender(self.0.clone())
+    }
+}
+
+
+impl<T> Clone for Sender<T> {
+    fn clone(&self) -> Sender<T> {
+        // Since this atomic op isn't actually guarding any memory and we don't
+        // care about any orderings besides the ordering on the single atomic
+        // variable, a relaxed ordering is acceptable.
+        let mut curr = self.inner.num_senders.load(SeqCst);
+
+        loop {
+            // If the maximum number of senders has been reached, then fail
+            if curr == self.inner.max_senders() {
+                panic!("cannot clone `Sender` -- too many outstanding senders");
+            }
+
+            debug_assert!(curr < self.inner.max_senders());
+
+            let next = curr + 1;
+            let actual = self.inner.num_senders.compare_and_swap(curr, next, SeqCst);
+
+            // The ABA problem doesn't matter here. We only care that the
+            // number of senders never exceeds the maximum.
+            if actual == curr {
+                return Sender {
+                    inner: self.inner.clone(),
+                    sender_task: Arc::new(Mutex::new(SenderTask::new())),
+                    maybe_parked: false,
+                };
+            }
+
+            curr = actual;
+        }
+    }
+}
+
+impl<T> Drop for Sender<T> {
+    fn drop(&mut self) {
+        // Ordering between variables don't matter here
+        let prev = self.inner.num_senders.fetch_sub(1, SeqCst);
+
+        if prev == 1 {
+            let _ = self.do_send(None, false);
+        }
+    }
+}
+
+/*
+ *
+ * ===== impl Receiver =====
+ *
+ */
+
+impl<T> Receiver<T> {
+    /// Closes the receiving half
+    ///
+    /// This prevents any further messages from being sent on the channel while
+    /// still enabling the receiver to drain messages that are buffered.
+    pub fn close(&mut self) {
+        let mut curr = self.inner.state.load(SeqCst);
+
+        loop {
+            let mut state = decode_state(curr);
+
+            if !state.is_open {
+                break
+            }
+
+            state.is_open = false;
+
+            let next = encode_state(&state);
+            match self.inner.state.compare_exchange(curr, next, SeqCst, SeqCst) {
+                Ok(_) => break,
+                Err(actual) => curr = actual,
+            }
+        }
+
+        // Wake up any threads waiting as they'll see that we've closed the
+        // channel and will continue on their merry way.
+        loop {
+            match unsafe { self.inner.parked_queue.pop() } {
+                PopResult::Data(task) => {
+                    task.lock().unwrap().notify();
+                }
+                PopResult::Empty => break,
+                PopResult::Inconsistent => thread::yield_now(),
+            }
+        }
+    }
+
+    fn next_message(&mut self) -> Async<Option<T>> {
+        // Pop off a message
+        loop {
+            match unsafe { self.inner.message_queue.pop() } {
+                PopResult::Data(msg) => {
+                    return Async::Ready(msg);
+                }
+                PopResult::Empty => {
+                    // The queue is empty, return NotReady
+                    return Async::NotReady;
+                }
+                PopResult::Inconsistent => {
+                    // Inconsistent means that there will be a message to pop
+                    // in a short time. This branch can only be reached if
+                    // values are being produced from another thread, so there
+                    // are a few ways that we can deal with this:
+                    //
+                    // 1) Spin
+                    // 2) thread::yield_now()
+                    // 3) task::current().unwrap() & return NotReady
+                    //
+                    // For now, thread::yield_now() is used, but it would
+                    // probably be better to spin a few times then yield.
+                    thread::yield_now();
+                }
+            }
+        }
+    }
+
+    // Unpark a single task handle if there is one pending in the parked queue
+    fn unpark_one(&mut self) {
+        loop {
+            match unsafe { self.inner.parked_queue.pop() } {
+                PopResult::Data(task) => {
+                    task.lock().unwrap().notify();
+                    return;
+                }
+                PopResult::Empty => {
+                    // Queue empty, no task to wake up.
+                    return;
+                }
+                PopResult::Inconsistent => {
+                    // Same as above
+                    thread::yield_now();
+                }
+            }
+        }
+    }
+
+    // Try to park the receiver task
+    fn try_park(&self) -> TryPark {
+        let curr = self.inner.state.load(SeqCst);
+        let state = decode_state(curr);
+
+        // If the channel is closed, then there is no need to park.
+        if !state.is_open && state.num_messages == 0 {
+            return TryPark::Closed;
+        }
+
+        // First, track the task in the `recv_task` slot
+        let mut recv_task = self.inner.recv_task.lock().unwrap();
+
+        if recv_task.unparked {
+            // Consume the `unpark` signal without actually parking
+            recv_task.unparked = false;
+            return TryPark::NotEmpty;
+        }
+
+        recv_task.task = Some(task::current());
+        TryPark::Parked
+    }
+
+    fn dec_num_messages(&self) {
+        let mut curr = self.inner.state.load(SeqCst);
+
+        loop {
+            let mut state = decode_state(curr);
+
+            state.num_messages -= 1;
+
+            let next = encode_state(&state);
+            match self.inner.state.compare_exchange(curr, next, SeqCst, SeqCst) {
+                Ok(_) => break,
+                Err(actual) => curr = actual,
+            }
+        }
+    }
+}
+
+impl<T> Stream for Receiver<T> {
+    type Item = T;
+    type Error = ();
+
+    fn poll(&mut self) -> Poll<Option<T>, ()> {
+        loop {
+            // Try to read a message off of the message queue.
+            let msg = match self.next_message() {
+                Async::Ready(msg) => msg,
+                Async::NotReady => {
+                    // There are no messages to read, in this case, attempt to
+                    // park. The act of parking will verify that the channel is
+                    // still empty after the park operation has completed.
+                    match self.try_park() {
+                        TryPark::Parked => {
+                            // The task was parked, and the channel is still
+                            // empty, return NotReady.
+                            return Ok(Async::NotReady);
+                        }
+                        TryPark::Closed => {
+                            // The channel is closed, there will be no further
+                            // messages.
+                            return Ok(Async::Ready(None));
+                        }
+                        TryPark::NotEmpty => {
+                            // A message has been sent while attempting to
+                            // park. Loop again, the next iteration is
+                            // guaranteed to get the message.
+                            continue;
+                        }
+                    }
+                }
+            };
+
+            // If there are any parked task handles in the parked queue, pop
+            // one and unpark it.
+            self.unpark_one();
+
+            // Decrement number of messages
+            self.dec_num_messages();
+
+            // Return the message
+            return Ok(Async::Ready(msg));
+        }
+    }
+}
+
+impl<T> Drop for Receiver<T> {
+    fn drop(&mut self) {
+        // Drain the channel of all pending messages
+        self.close();
+        while self.next_message().is_ready() {
+            // ...
+        }
+    }
+}
+
+/*
+ *
+ * ===== impl Inner =====
+ *
+ */
+
+impl<T> Inner<T> {
+    // The return value is such that the total number of messages that can be
+    // enqueued into the channel will never exceed MAX_CAPACITY
+    fn max_senders(&self) -> usize {
+        match self.buffer {
+            Some(buffer) => MAX_CAPACITY - buffer,
+            None => MAX_BUFFER,
+        }
+    }
+}
+
+unsafe impl<T: Send> Send for Inner<T> {}
+unsafe impl<T: Send> Sync for Inner<T> {}
+
+/*
+ *
+ * ===== Helpers =====
+ *
+ */
+
+fn decode_state(num: usize) -> State {
+    State {
+        is_open: num & OPEN_MASK == OPEN_MASK,
+        num_messages: num & MAX_CAPACITY,
+    }
+}
+
+fn encode_state(state: &State) -> usize {
+    let mut num = state.num_messages;
+
+    if state.is_open {
+        num |= OPEN_MASK;
+    }
+
+    num
+}

tokio-channel/src/mpsc/queue.rs

@@ -0,0 +1,151 @@
+/* Copyright (c) 2010-2011 Dmitry Vyukov. All rights reserved.
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *    1. Redistributions of source code must retain the above copyright notice,
+ *       this list of conditions and the following disclaimer.
+ *
+ *    2. Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY DMITRY VYUKOV "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL DMITRY VYUKOV OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * The views and conclusions contained in the software and documentation are
+ * those of the authors and should not be interpreted as representing official
+ * policies, either expressed or implied, of Dmitry Vyukov.
+ */
+
+//! A mostly lock-free multi-producer, single consumer queue.
+//!
+//! This module contains an implementation of a concurrent MPSC queue. This
+//! queue can be used to share data between threads, and is also used as the
+//! building block of channels in rust.
+//!
+//! Note that the current implementation of this queue has a caveat of the `pop`
+//! method, and see the method for more information about it. Due to this
+//! caveat, this queue may not be appropriate for all use-cases.
+
+// http://www.1024cores.net/home/lock-free-algorithms
+//                         /queues/non-intrusive-mpsc-node-based-queue
+
+// NOTE: this implementation is lifted from the standard library and only
+//       slightly modified
+
+pub use self::PopResult::*;
+use std::prelude::v1::*;
+
+use std::cell::UnsafeCell;
+use std::ptr;
+use std::sync::atomic::{AtomicPtr, Ordering};
+
+/// A result of the `pop` function.
+pub enum PopResult<T> {
+    /// Some data has been popped
+    Data(T),
+    /// The queue is empty
+    Empty,
+    /// The queue is in an inconsistent state. Popping data should succeed, but
+    /// some pushers have yet to make enough progress in order allow a pop to
+    /// succeed. It is recommended that a pop() occur "in the near future" in
+    /// order to see if the sender has made progress or not
+    Inconsistent,
+}
+
+#[derive(Debug)]
+struct Node<T> {
+    next: AtomicPtr<Node<T>>,
+    value: Option<T>,
+}
+
+/// The multi-producer single-consumer structure. This is not cloneable, but it
+/// may be safely shared so long as it is guaranteed that there is only one
+/// popper at a time (many pushers are allowed).
+#[derive(Debug)]
+pub struct Queue<T> {
+    head: AtomicPtr<Node<T>>,
+    tail: UnsafeCell<*mut Node<T>>,
+}
+
+unsafe impl<T: Send> Send for Queue<T> { }
+unsafe impl<T: Send> Sync for Queue<T> { }
+
+impl<T> Node<T> {
+    unsafe fn new(v: Option<T>) -> *mut Node<T> {
+        Box::into_raw(Box::new(Node {
+            next: AtomicPtr::new(ptr::null_mut()),
+            value: v,
+        }))
+    }
+}
+
+impl<T> Queue<T> {
+    /// Creates a new queue that is safe to share among multiple producers and
+    /// one consumer.
+    pub fn new() -> Queue<T> {
+        let stub = unsafe { Node::new(None) };
+        Queue {
+            head: AtomicPtr::new(stub),
+            tail: UnsafeCell::new(stub),
+        }
+    }
+
+    /// Pushes a new value onto this queue.
+    pub fn push(&self, t: T) {
+        unsafe {
+            let n = Node::new(Some(t));
+            let prev = self.head.swap(n, Ordering::AcqRel);
+            (*prev).next.store(n, Ordering::Release);
+        }
+    }
+
+    /// Pops some data from this queue.
+    ///
+    /// Note that the current implementation means that this function cannot
+    /// return `Option<T>`. It is possible for this queue to be in an
+    /// inconsistent state where many pushes have succeeded and completely
+    /// finished, but pops cannot return `Some(t)`. This inconsistent state
+    /// happens when a pusher is preempted at an inopportune moment.
+    ///
+    /// This inconsistent state means that this queue does indeed have data, but
+    /// it does not currently have access to it at this time.
+    ///
+    /// This function is unsafe because only one thread can call it at a time.
+    pub unsafe fn pop(&self) -> PopResult<T> {
+        let tail = *self.tail.get();
+        let next = (*tail).next.load(Ordering::Acquire);
+
+        if !next.is_null() {
+            *self.tail.get() = next;
+            assert!((*tail).value.is_none());
+            assert!((*next).value.is_some());
+            let ret = (*next).value.take().unwrap();
+            drop(Box::from_raw(tail));
+            return Data(ret);
+        }
+
+        if self.head.load(Ordering::Acquire) == tail {Empty} else {Inconsistent}
+    }
+}
+
+impl<T> Drop for Queue<T> {
+    fn drop(&mut self) {
+        unsafe {
+            let mut cur = *self.tail.get();
+            while !cur.is_null() {
+                let next = (*cur).next.load(Ordering::Relaxed);
+                drop(Box::from_raw(cur));
+                cur = next;
+            }
+        }
+    }
+}

tokio-channel/src/oneshot.rs

@@ -0,0 +1,426 @@
+//! A one-shot, futures-aware channel
+
+use lock::Lock;
+
+use futures::{Future, Poll, Async};
+use futures::task::{self, Task};
+
+use std::sync::Arc;
+use std::sync::atomic::AtomicBool;
+use std::sync::atomic::Ordering::SeqCst;
+use std::error::Error;
+use std::fmt;
+
+/// A future representing the completion of a computation happening elsewhere in
+/// memory.
+///
+/// This is created by the `oneshot::channel` function.
+#[must_use = "futures do nothing unless polled"]
+#[derive(Debug)]
+pub struct Receiver<T> {
+    inner: Arc<Inner<T>>,
+}
+
+/// Represents the completion half of a oneshot through which the result of a
+/// computation is signaled.
+///
+/// This is created by the `oneshot::channel` function.
+#[derive(Debug)]
+pub struct Sender<T> {
+    inner: Arc<Inner<T>>,
+}
+
+/// Internal state of the `Receiver`/`Sender` pair above. This is all used as
+/// the internal synchronization between the two for send/recv operations.
+#[derive(Debug)]
+struct Inner<T> {
+    /// Indicates whether this oneshot is complete yet. This is filled in both
+    /// by `Sender::drop` and by `Receiver::drop`, and both sides interpret it
+    /// appropriately.
+    ///
+    /// For `Receiver`, if this is `true`, then it's guaranteed that `data` is
+    /// unlocked and ready to be inspected.
+    ///
+    /// For `Sender` if this is `true` then the oneshot has gone away and it
+    /// can return ready from `poll_cancel`.
+    complete: AtomicBool,
+
+    /// The actual data being transferred as part of this `Receiver`. This is
+    /// filled in by `Sender::complete` and read by `Receiver::poll`.
+    ///
+    /// Note that this is protected by `Lock`, but it is in theory safe to
+    /// replace with an `UnsafeCell` as it's actually protected by `complete`
+    /// above. I wouldn't recommend doing this, however, unless someone is
+    /// supremely confident in the various atomic orderings here and there.
+    data: Lock<Option<T>>,
+
+    /// Field to store the task which is blocked in `Receiver::poll`.
+    ///
+    /// This is filled in when a oneshot is polled but not ready yet. Note that
+    /// the `Lock` here, unlike in `data` above, is important to resolve races.
+    /// Both the `Receiver` and the `Sender` halves understand that if they
+    /// can't acquire the lock then some important interference is happening.
+    rx_task: Lock<Option<Task>>,
+
+    /// Like `rx_task` above, except for the task blocked in
+    /// `Sender::poll_cancel`. Additionally, `Lock` cannot be `UnsafeCell`.
+    tx_task: Lock<Option<Task>>,
+}
+
+/// Creates a new futures-aware, one-shot channel.
+///
+/// This function is similar to Rust's channels found in the standard library.
+/// Two halves are returned, the first of which is a `Sender` handle, used to
+/// signal the end of a computation and provide its value. The second half is a
+/// `Receiver` which implements the `Future` trait, resolving to the value that
+/// was given to the `Sender` handle.
+///
+/// Each half can be separately owned and sent across threads/tasks.
+///
+/// # Examples
+///
+/// ```
+/// extern crate tokio_channel;
+/// extern crate futures;
+///
+/// use tokio_channel::oneshot;
+/// use futures::*;
+/// use std::thread;
+///
+/// # fn main() {
+/// let (p, c) = oneshot::channel::<i32>();
+///
+/// thread::spawn(|| {
+///     c.map(|i| {
+///         println!("got: {}", i);
+///     }).wait();
+/// });
+///
+/// p.send(3).unwrap();
+/// # }
+/// ```
+pub fn channel<T>() -> (Sender<T>, Receiver<T>) {
+    let inner = Arc::new(Inner::new());
+    let receiver = Receiver {
+        inner: inner.clone(),
+    };
+    let sender = Sender {
+        inner: inner,
+    };
+    (sender, receiver)
+}
+
+impl<T> Inner<T> {
+    fn new() -> Inner<T> {
+        Inner {
+            complete: AtomicBool::new(false),
+            data: Lock::new(None),
+            rx_task: Lock::new(None),
+            tx_task: Lock::new(None),
+        }
+    }
+
+    fn send(&self, t: T) -> Result<(), T> {
+        if self.complete.load(SeqCst) {
+            return Err(t)
+        }
+
+        // Note that this lock acquisition may fail if the receiver
+        // is closed and sets the `complete` flag to true, whereupon
+        // the receiver may call `poll()`.
+        if let Some(mut slot) = self.data.try_lock() {
+            assert!(slot.is_none());
+            *slot = Some(t);
+            drop(slot);
+
+            // If the receiver called `close()` between the check at the
+            // start of the function, and the lock being released, then
+            // the receiver may not be around to receive it, so try to
+            // pull it back out.
+            if self.complete.load(SeqCst) {
+                // If lock acquisition fails, then receiver is actually
+                // receiving it, so we're good.
+                if let Some(mut slot) = self.data.try_lock() {
+                    if let Some(t) = slot.take() {
+                        return Err(t);
+                    }
+                }
+            }
+            Ok(())
+        } else {
+            // Must have been closed
+            Err(t)
+        }
+    }
+
+    fn poll_cancel(&self) -> Poll<(), ()> {
+        // Fast path up first, just read the flag and see if our other half is
+        // gone. This flag is set both in our destructor and the oneshot
+        // destructor, but our destructor hasn't run yet so if it's set then the
+        // oneshot is gone.
+        if self.complete.load(SeqCst) {
+            return Ok(Async::Ready(()))
+        }
+
+        // If our other half is not gone then we need to park our current task
+        // and move it into the `notify_cancel` slot to get notified when it's
+        // actually gone.
+        //
+        // If `try_lock` fails, then the `Receiver` is in the process of using
+        // it, so we can deduce that it's now in the process of going away and
+        // hence we're canceled. If it succeeds then we just store our handle.
+        //
+        // Crucially we then check `oneshot_gone` *again* before we return.
+        // While we were storing our handle inside `notify_cancel` the `Receiver`
+        // may have been dropped. The first thing it does is set the flag, and
+        // if it fails to acquire the lock it assumes that we'll see the flag
+        // later on. So... we then try to see the flag later on!
+        let handle = task::current();
+        match self.tx_task.try_lock() {
+            Some(mut p) => *p = Some(handle),
+            None => return Ok(Async::Ready(())),
+        }
+        if self.complete.load(SeqCst) {
+            Ok(Async::Ready(()))
+        } else {
+            Ok(Async::NotReady)
+        }
+    }
+
+    fn is_canceled(&self) -> bool {
+        self.complete.load(SeqCst)
+    }
+
+    fn drop_tx(&self) {
+        // Flag that we're a completed `Sender` and try to wake up a receiver.
+        // Whether or not we actually stored any data will get picked up and
+        // translated to either an item or cancellation.
+        //
+        // Note that if we fail to acquire the `rx_task` lock then that means
+        // we're in one of two situations:
+        //
+        // 1. The receiver is trying to block in `poll`
+        // 2. The receiver is being dropped
+        //
+        // In the first case it'll check the `complete` flag after it's done
+        // blocking to see if it succeeded. In the latter case we don't need to
+        // wake up anyone anyway. So in both cases it's ok to ignore the `None`
+        // case of `try_lock` and bail out.
+        //
+        // The first case crucially depends on `Lock` using `SeqCst` ordering
+        // under the hood. If it instead used `Release` / `Acquire` ordering,
+        // then it would not necessarily synchronize with `inner.complete`
+        // and deadlock might be possible, as was observed in
+        // https://github.com/rust-lang-nursery/futures-rs/pull/219.
+        self.complete.store(true, SeqCst);
+        if let Some(mut slot) = self.rx_task.try_lock() {
+            if let Some(task) = slot.take() {
+                drop(slot);
+                task.notify();
+            }
+        }
+    }
+
+    fn close_rx(&self) {
+        // Flag our completion and then attempt to wake up the sender if it's
+        // blocked. See comments in `drop` below for more info
+        self.complete.store(true, SeqCst);
+        if let Some(mut handle) = self.tx_task.try_lock() {
+            if let Some(task) = handle.take() {
+                drop(handle);
+                task.notify()
+            }
+        }
+    }
+
+    fn recv(&self) -> Poll<T, Canceled> {
+        let mut done = false;
+
+        // Check to see if some data has arrived. If it hasn't then we need to
+        // block our task.
+        //
+        // Note that the acquisition of the `rx_task` lock might fail below, but
+        // the only situation where this can happen is during `Sender::drop`
+        // when we are indeed completed already. If that's happening then we
+        // know we're completed so keep going.
+        if self.complete.load(SeqCst) {
+            done = true;
+        } else {
+            let task = task::current();
+            match self.rx_task.try_lock() {
+                Some(mut slot) => *slot = Some(task),
+                None => done = true,
+            }
+        }
+
+        // If we're `done` via one of the paths above, then look at the data and
+        // figure out what the answer is. If, however, we stored `rx_task`
+        // successfully above we need to check again if we're completed in case
+        // a message was sent while `rx_task` was locked and couldn't notify us
+        // otherwise.
+        //
+        // If we're not done, and we're not complete, though, then we've
+        // successfully blocked our task and we return `NotReady`.
+        if done || self.complete.load(SeqCst) {
+            // If taking the lock fails, the sender will realise that the we're
+            // `done` when it checks the `complete` flag on the way out, and will
+            // treat the send as a failure.
+            if let Some(mut slot) = self.data.try_lock() {
+                if let Some(data) = slot.take() {
+                    return Ok(data.into());
+                }
+            }
+            Err(Canceled)
+        } else {
+            Ok(Async::NotReady)
+        }
+    }
+
+    fn drop_rx(&self) {
+        // Indicate to the `Sender` that we're done, so any future calls to
+        // `poll_cancel` are weeded out.
+        self.complete.store(true, SeqCst);
+
+        // If we've blocked a task then there's no need for it to stick around,
+        // so we need to drop it. If this lock acquisition fails, though, then
+        // it's just because our `Sender` is trying to take the task, so we
+        // let them take care of that.
+        if let Some(mut slot) = self.rx_task.try_lock() {
+            let task = slot.take();
+            drop(slot);
+            drop(task);
+        }
+
+        // Finally, if our `Sender` wants to get notified of us going away, it
+        // would have stored something in `tx_task`. Here we try to peel that
+        // out and unpark it.
+        //
+        // Note that the `try_lock` here may fail, but only if the `Sender` is
+        // in the process of filling in the task. If that happens then we
+        // already flagged `complete` and they'll pick that up above.
+        if let Some(mut handle) = self.tx_task.try_lock() {
+            if let Some(task) = handle.take() {
+                drop(handle);
+                task.notify()
+            }
+        }
+    }
+}
+
+impl<T> Sender<T> {
+    #[deprecated(note = "renamed to `send`", since = "0.1.11")]
+    #[doc(hidden)]
+    #[cfg(feature = "with-deprecated")]
+    pub fn complete(self, t: T) {
+        drop(self.send(t));
+    }
+
+    /// Completes this oneshot with a successful result.
+    ///
+    /// This function will consume `self` and indicate to the other end, the
+    /// `Receiver`, that the value provided is the result of the computation this
+    /// represents.
+    ///
+    /// If the value is successfully enqueued for the remote end to receive,
+    /// then `Ok(())` is returned. If the receiving end was deallocated before
+    /// this function was called, however, then `Err` is returned with the value
+    /// provided.
+    pub fn send(self, t: T) -> Result<(), T> {
+        self.inner.send(t)
+    }
+
+    /// Polls this `Sender` half to detect whether the `Receiver` this has
+    /// paired with has gone away.
+    ///
+    /// This function can be used to learn about when the `Receiver` (consumer)
+    /// half has gone away and nothing will be able to receive a message sent
+    /// from `send`.
+    ///
+    /// If `Ready` is returned then it means that the `Receiver` has disappeared
+    /// and the result this `Sender` would otherwise produce should no longer
+    /// be produced.
+    ///
+    /// If `NotReady` is returned then the `Receiver` is still alive and may be
+    /// able to receive a message if sent. The current task, however, is
+    /// scheduled to receive a notification if the corresponding `Receiver` goes
+    /// away.
+    ///
+    /// # Panics
+    ///
+    /// Like `Future::poll`, this function will panic if it's not called from
+    /// within the context of a task. In other words, this should only ever be
+    /// called from inside another future.
+    ///
+    /// If you're calling this function from a context that does not have a
+    /// task, then you can use the `is_canceled` API instead.
+    pub fn poll_cancel(&mut self) -> Poll<(), ()> {
+        self.inner.poll_cancel()
+    }
+
+    /// Tests to see whether this `Sender`'s corresponding `Receiver`
+    /// has gone away.
+    ///
+    /// This function can be used to learn about when the `Receiver` (consumer)
+    /// half has gone away and nothing will be able to receive a message sent
+    /// from `send`.
+    ///
+    /// Note that this function is intended to *not* be used in the context of a
+    /// future. If you're implementing a future you probably want to call the
+    /// `poll_cancel` function which will block the current task if the
+    /// cancellation hasn't happened yet. This can be useful when working on a
+    /// non-futures related thread, though, which would otherwise panic if
+    /// `poll_cancel` were called.
+    pub fn is_canceled(&self) -> bool {
+        self.inner.is_canceled()
+    }
+}
+
+impl<T> Drop for Sender<T> {
+    fn drop(&mut self) {
+        self.inner.drop_tx()
+    }
+}
+
+/// Error returned from a `Receiver<T>` whenever the corresponding `Sender<T>`
+/// is dropped.
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub struct Canceled;
+
+impl fmt::Display for Canceled {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "oneshot canceled")
+    }
+}
+
+impl Error for Canceled {
+    fn description(&self) -> &str {
+        "oneshot canceled"
+    }
+}
+
+impl<T> Receiver<T> {
+    /// Gracefully close this receiver, preventing sending any future messages.
+    ///
+    /// Any `send` operation which happens after this method returns is
+    /// guaranteed to fail. Once this method is called the normal `poll` method
+    /// can be used to determine whether a message was actually sent or not. If
+    /// `Canceled` is returned from `poll` then no message was sent.
+    pub fn close(&mut self) {
+        self.inner.close_rx()
+    }
+}
+
+impl<T> Future for Receiver<T> {
+    type Item = T;
+    type Error = Canceled;
+
+    fn poll(&mut self) -> Poll<T, Canceled> {
+        self.inner.recv()
+    }
+}
+
+impl<T> Drop for Receiver<T> {
+    fn drop(&mut self) {
+        self.inner.drop_rx()
+    }
+}

tokio-channel/tests/mpsc-close.rs

@@ -0,0 +1,22 @@
+extern crate tokio_channel;
+extern crate futures;
+
+
+use tokio_channel::mpsc::*;
+use futures::prelude::*;
+use std::thread;
+
+#[test]
+fn smoke() {
+    let (mut sender, receiver) = channel(1);
+
+    let t = thread::spawn(move ||{
+        while let Ok(s) = sender.send(42).wait() {
+            sender = s;
+        }
+    });
+
+    receiver.take(3).for_each(|_| Ok(())).wait().unwrap();
+
+    t.join().unwrap()
+}

tokio-channel/tests/mpsc.rs

@@ -0,0 +1,481 @@
+extern crate tokio_channel;
+#[macro_use]
+extern crate futures;
+
+mod support;
+use support::*;
+
+use tokio_channel::mpsc;
+use tokio_channel::oneshot;
+
+use futures::prelude::*;
+use futures::future::lazy;
+
+use std::thread;
+use std::sync::{Arc, Mutex};
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+trait AssertSend: Send {}
+impl AssertSend for mpsc::Sender<i32> {}
+impl AssertSend for mpsc::Receiver<i32> {}
+
+#[test]
+fn send_recv() {
+    let (tx, rx) = mpsc::channel::<i32>(16);
+    let mut rx = rx.wait();
+
+    tx.send(1).wait().unwrap();
+
+    assert_eq!(rx.next().unwrap(), Ok(1));
+}
+
+#[test]
+fn send_recv_no_buffer() {
+    let (mut tx, mut rx) = mpsc::channel::<i32>(0);
+
+    // Run on a task context
+    lazy(move || {
+        assert!(tx.poll_complete().unwrap().is_ready());
+        assert!(tx.poll_ready().unwrap().is_ready());
+
+        // Send first message
+        let res = tx.start_send(1).unwrap();
+        assert!(is_ready(&res));
+        assert!(tx.poll_ready().unwrap().is_not_ready());
+
+        // Send second message
+        let res = tx.start_send(2).unwrap();
+        assert!(!is_ready(&res));
+
+        // Take the value
+        assert_eq!(rx.poll().unwrap(), Async::Ready(Some(1)));
+        assert!(tx.poll_ready().unwrap().is_ready());
+
+        let res = tx.start_send(2).unwrap();
+        assert!(is_ready(&res));
+        assert!(tx.poll_ready().unwrap().is_not_ready());
+
+        // Take the value
+        assert_eq!(rx.poll().unwrap(), Async::Ready(Some(2)));
+        assert!(tx.poll_ready().unwrap().is_ready());
+
+        Ok::<(), ()>(())
+    }).wait().unwrap();
+}
+
+#[test]
+fn send_shared_recv() {
+    let (tx1, rx) = mpsc::channel::<i32>(16);
+    let tx2 = tx1.clone();
+    let mut rx = rx.wait();
+
+    tx1.send(1).wait().unwrap();
+    assert_eq!(rx.next().unwrap(), Ok(1));
+
+    tx2.send(2).wait().unwrap();
+    assert_eq!(rx.next().unwrap(), Ok(2));
+}
+
+#[test]
+fn send_recv_threads() {
+    let (tx, rx) = mpsc::channel::<i32>(16);
+    let mut rx = rx.wait();
+
+    thread::spawn(move|| {
+        tx.send(1).wait().unwrap();
+    });
+
+    assert_eq!(rx.next().unwrap(), Ok(1));
+}
+
+#[test]
+fn send_recv_threads_no_capacity() {
+    let (tx, rx) = mpsc::channel::<i32>(0);
+    let mut rx = rx.wait();
+
+    let (readytx, readyrx) = mpsc::channel::<()>(2);
+    let mut readyrx = readyrx.wait();
+    let t = thread::spawn(move|| {
+        let readytx = readytx.sink_map_err(|_| panic!());
+        let (a, b) = tx.send(1).join(readytx.send(())).wait().unwrap();
+        a.send(2).join(b.send(())).wait().unwrap();
+    });
+
+    drop(readyrx.next().unwrap());
+    assert_eq!(rx.next().unwrap(), Ok(1));
+    drop(readyrx.next().unwrap());
+    assert_eq!(rx.next().unwrap(), Ok(2));
+
+    t.join().unwrap();
+}
+
+#[test]
+fn recv_close_gets_none() {
+    let (mut tx, mut rx) = mpsc::channel::<i32>(10);
+
+    // Run on a task context
+    lazy(move || {
+        rx.close();
+
+        assert_eq!(rx.poll(), Ok(Async::Ready(None)));
+        assert!(tx.poll_ready().is_err());
+
+        drop(tx);
+
+        Ok::<(), ()>(())
+    }).wait().unwrap();
+}
+
+
+#[test]
+fn tx_close_gets_none() {
+    let (_, mut rx) = mpsc::channel::<i32>(10);
+
+    // Run on a task context
+    lazy(move || {
+        assert_eq!(rx.poll(), Ok(Async::Ready(None)));
+        assert_eq!(rx.poll(), Ok(Async::Ready(None)));
+
+        Ok::<(), ()>(())
+    }).wait().unwrap();
+}
+
+#[test]
+fn stress_shared_unbounded() {
+    const AMT: u32 = 10000;
+    const NTHREADS: u32 = 8;
+    let (tx, rx) = mpsc::unbounded::<i32>();
+    let mut rx = rx.wait();
+
+    let t = thread::spawn(move|| {
+        for _ in 0..AMT * NTHREADS {
+            assert_eq!(rx.next().unwrap(), Ok(1));
+        }
+
+        if rx.next().is_some() {
+            panic!();
+        }
+    });
+
+    for _ in 0..NTHREADS {
+        let tx = tx.clone();
+
+        thread::spawn(move|| {
+            for _ in 0..AMT {
+                tx.unbounded_send(1).unwrap();
+            }
+        });
+    }
+
+    drop(tx);
+
+    t.join().ok().unwrap();
+}
+
+#[test]
+fn stress_shared_bounded_hard() {
+    const AMT: u32 = 10000;
+    const NTHREADS: u32 = 8;
+    let (tx, rx) = mpsc::channel::<i32>(0);
+    let mut rx = rx.wait();
+
+    let t = thread::spawn(move|| {
+        for _ in 0..AMT * NTHREADS {
+            assert_eq!(rx.next().unwrap(), Ok(1));
+        }
+
+        if rx.next().is_some() {
+            panic!();
+        }
+    });
+
+    for _ in 0..NTHREADS {
+        let mut tx = tx.clone();
+
+        thread::spawn(move|| {
+            for _ in 0..AMT {
+                tx = tx.send(1).wait().unwrap();
+            }
+        });
+    }
+
+    drop(tx);
+
+    t.join().ok().unwrap();
+}
+
+#[test]
+fn stress_receiver_multi_task_bounded_hard() {
+    const AMT: usize = 10_000;
+    const NTHREADS: u32 = 2;
+
+    let (mut tx, rx) = mpsc::channel::<usize>(0);
+    let rx = Arc::new(Mutex::new(Some(rx)));
+    let n = Arc::new(AtomicUsize::new(0));
+
+    let mut th = vec![];
+
+    for _ in 0..NTHREADS {
+        let rx = rx.clone();
+        let n = n.clone();
+
+        let t = thread::spawn(move || {
+            let mut i = 0;
+
+            loop {
+                i += 1;
+                let mut lock = rx.lock().ok().unwrap();
+
+                match lock.take() {
+                    Some(mut rx) => {
+                        if i % 5 == 0 {
+                            let (item, rest) = rx.into_future().wait().ok().unwrap();
+
+                            if item.is_none() {
+                                break;
+                            }
+
+                            n.fetch_add(1, Ordering::Relaxed);
+                            *lock = Some(rest);
+                        } else {
+                            // Just poll
+                            let n = n.clone();
+                            let r = lazy(move || {
+                                let r = match rx.poll().unwrap() {
+                                    Async::Ready(Some(_)) => {
+                                        n.fetch_add(1, Ordering::Relaxed);
+                                        *lock = Some(rx);
+                                        false
+                                    }
+                                    Async::Ready(None) => {
+                                        true
+                                    }
+                                    Async::NotReady => {
+                                        *lock = Some(rx);
+                                        false
+                                    }
+                                };
+
+                                Ok::<bool, ()>(r)
+                            }).wait().unwrap();
+
+                            if r {
+                                break;
+                            }
+                        }
+                    }
+                    None => break,
+                }
+            }
+        });
+
+        th.push(t);
+    }
+
+    for i in 0..AMT {
+        tx = tx.send(i).wait().unwrap();
+    }
+
+    drop(tx);
+
+    for t in th {
+        t.join().unwrap();
+    }
+
+    assert_eq!(AMT, n.load(Ordering::Relaxed));
+}
+
+/// Stress test that receiver properly receives all the messages
+/// after sender dropped.
+#[test]
+fn stress_drop_sender() {
+    fn list() -> Box<Stream<Item=i32, Error=u32>> {
+        let (tx, rx) = mpsc::channel(1);
+        tx.send(Ok(1))
+          .and_then(|tx| tx.send(Ok(2)))
+          .and_then(|tx| tx.send(Ok(3)))
+          .forget();
+        Box::new(rx.then(|r| r.unwrap()))
+    }
+
+    for _ in 0..10000 {
+        assert_eq!(list().wait().collect::<Result<Vec<_>, _>>(),
+        Ok(vec![1, 2, 3]));
+    }
+}
+
+/// Stress test that after receiver dropped,
+/// no messages are lost.
+fn stress_close_receiver_iter() {
+    let (tx, rx) = mpsc::unbounded();
+    let (unwritten_tx, unwritten_rx) = std::sync::mpsc::channel();
+    let th = thread::spawn(move || {
+        for i in 1.. {
+            if let Err(_) = tx.unbounded_send(i) {
+                unwritten_tx.send(i).expect("unwritten_tx");
+                return;
+            }
+        }
+    });
+
+    let mut rx = rx.wait();
+
+    // Read one message to make sure thread effectively started
+    assert_eq!(Some(Ok(1)), rx.next());
+
+    rx.get_mut().close();
+
+    for i in 2.. {
+        match rx.next() {
+            Some(Ok(r)) => assert!(i == r),
+            Some(Err(_)) => unreachable!(),
+            None => {
+                let unwritten = unwritten_rx.recv().expect("unwritten_rx");
+                assert_eq!(unwritten, i);
+                th.join().unwrap();
+                return;
+            }
+        }
+    }
+}
+
+#[test]
+fn stress_close_receiver() {
+    for _ in 0..10000 {
+        stress_close_receiver_iter();
+    }
+}
+
+/// Tests that after `poll_ready` indicates capacity a channel can always send without waiting.
+#[test]
+fn stress_poll_ready() {
+    // A task which checks channel capacity using poll_ready, and pushes items onto the channel when
+    // ready.
+    struct SenderTask {
+        sender: mpsc::Sender<u32>,
+        count: u32,
+    }
+    impl Future for SenderTask {
+        type Item = ();
+        type Error = ();
+        fn poll(&mut self) -> Poll<(), ()> {
+            // In a loop, check if the channel is ready. If so, push an item onto the channel
+            // (asserting that it doesn't attempt to block).
+            while self.count > 0 {
+                try_ready!(self.sender.poll_ready().map_err(|_| ()));
+                assert!(self.sender.start_send(self.count).unwrap().is_ready());
+                self.count -= 1;
+            }
+            Ok(Async::Ready(()))
+        }
+    }
+
+    const AMT: u32 = 1000;
+    const NTHREADS: u32 = 8;
+
+    /// Run a stress test using the specified channel capacity.
+    fn stress(capacity: usize) {
+        let (tx, rx) = mpsc::channel(capacity);
+        let mut threads = Vec::new();
+        for _ in 0..NTHREADS {
+            let sender = tx.clone();
+            threads.push(thread::spawn(move || {
+                SenderTask {
+                    sender: sender,
+                    count: AMT,
+                }.wait()
+            }));
+        }
+        drop(tx);
+
+        let mut rx = rx.wait();
+        for _ in 0..AMT * NTHREADS {
+            assert!(rx.next().is_some());
+        }
+
+        assert!(rx.next().is_none());
+
+        for thread in threads {
+            thread.join().unwrap().unwrap();
+        }
+    }
+
+    stress(0);
+    stress(1);
+    stress(8);
+    stress(16);
+}
+
+fn is_ready<T>(res: &AsyncSink<T>) -> bool {
+    match *res {
+        AsyncSink::Ready => true,
+        _ => false,
+    }
+}
+
+#[test]
+fn try_send_1() {
+    const N: usize = 3000;
+    let (mut tx, rx) = mpsc::channel(0);
+
+    let t = thread::spawn(move || {
+        for i in 0..N {
+            loop {
+                if tx.try_send(i).is_ok() {
+                    break
+                }
+            }
+        }
+    });
+    for (i, j) in rx.wait().enumerate() {
+        assert_eq!(i, j.unwrap());
+    }
+    t.join().unwrap();
+}
+
+#[test]
+fn try_send_2() {
+    let (mut tx, rx) = mpsc::channel(0);
+
+    tx.try_send("hello").unwrap();
+
+    let (readytx, readyrx) = oneshot::channel::<()>();
+
+    let th = thread::spawn(|| {
+        lazy(|| {
+            assert!(tx.start_send("fail").unwrap().is_not_ready());
+            Ok::<_, ()>(())
+        }).wait().unwrap();
+
+        drop(readytx);
+        tx.send("goodbye").wait().unwrap();
+    });
+
+    let mut rx = rx.wait();
+
+    drop(readyrx.wait());
+    assert_eq!(rx.next(), Some(Ok("hello")));
+    assert_eq!(rx.next(), Some(Ok("goodbye")));
+    assert!(rx.next().is_none());
+
+    th.join().unwrap();
+}
+
+#[test]
+fn try_send_fail() {
+    let (mut tx, rx) = mpsc::channel(0);
+    let mut rx = rx.wait();
+
+    tx.try_send("hello").unwrap();
+
+    // This should fail
+    assert!(tx.try_send("fail").is_err());
+
+    assert_eq!(rx.next(), Some(Ok("hello")));
+
+    tx.try_send("goodbye").unwrap();
+    drop(tx);
+
+    assert_eq!(rx.next(), Some(Ok("goodbye")));
+    assert!(rx.next().is_none());
+}

tokio-channel/tests/oneshot.rs

@@ -0,0 +1,124 @@
+extern crate tokio_channel;
+extern crate futures;
+
+mod support;
+use support::*;
+
+use tokio_channel::oneshot::*;
+
+use futures::prelude::*;
+use futures::future::{lazy, ok};
+
+use std::sync::mpsc;
+use std::thread;
+
+#[test]
+fn smoke_poll() {
+    let (mut tx, rx) = channel::<u32>();
+
+    lazy(|| {
+        assert!(tx.poll_cancel().unwrap().is_not_ready());
+        assert!(tx.poll_cancel().unwrap().is_not_ready());
+        drop(rx);
+        assert!(tx.poll_cancel().unwrap().is_ready());
+        assert!(tx.poll_cancel().unwrap().is_ready());
+        ok::<(), ()>(())
+    }).wait().unwrap();
+}
+
+#[test]
+fn cancel_notifies() {
+    let (tx, rx) = channel::<u32>();
+    let (tx2, rx2) = mpsc::channel();
+
+    WaitForCancel { tx: tx }.then(move |v| tx2.send(v)).forget();
+    drop(rx);
+    rx2.recv().unwrap().unwrap();
+}
+
+struct WaitForCancel {
+    tx: Sender<u32>,
+}
+
+impl Future for WaitForCancel {
+    type Item = ();
+    type Error = ();
+
+    fn poll(&mut self) -> Poll<(), ()> {
+        self.tx.poll_cancel()
+    }
+}
+
+#[test]
+fn cancel_lots() {
+    let (tx, rx) = mpsc::channel::<(Sender<_>, mpsc::Sender<_>)>();
+    let t = thread::spawn(move || {
+        for (tx, tx2) in rx {
+            WaitForCancel { tx: tx }.then(move |v| tx2.send(v)).forget();
+        }
+
+    });
+
+    for _ in 0..20000 {
+        let (otx, orx) = channel::<u32>();
+        let (tx2, rx2) = mpsc::channel();
+        tx.send((otx, tx2)).unwrap();
+        drop(orx);
+        rx2.recv().unwrap().unwrap();
+    }
+    drop(tx);
+
+    t.join().unwrap();
+}
+
+#[test]
+fn close() {
+    let (mut tx, mut rx) = channel::<u32>();
+    rx.close();
+    assert!(rx.poll().is_err());
+    assert!(tx.poll_cancel().unwrap().is_ready());
+}
+
+#[test]
+fn close_wakes() {
+    let (tx, mut rx) = channel::<u32>();
+    let (tx2, rx2) = mpsc::channel();
+    let t = thread::spawn(move || {
+        rx.close();
+        rx2.recv().unwrap();
+    });
+    WaitForCancel { tx: tx }.wait().unwrap();
+    tx2.send(()).unwrap();
+    t.join().unwrap();
+}
+
+#[test]
+fn is_canceled() {
+    let (tx, rx) = channel::<u32>();
+    assert!(!tx.is_canceled());
+    drop(rx);
+    assert!(tx.is_canceled());
+}
+
+#[test]
+fn cancel_sends() {
+    let (tx, rx) = mpsc::channel::<Sender<_>>();
+    let t = thread::spawn(move || {
+        for otx in rx {
+            let _ = otx.send(42);
+        }
+    });
+
+    for _ in 0..20000 {
+        let (otx, mut orx) = channel::<u32>();
+        tx.send(otx).unwrap();
+
+        orx.close();
+        // Not necessary to wrap in a task because the implementation of oneshot
+        // never calls `task::current()` if the channel has been closed already.
+        let _ = orx.poll();
+    }
+
+    drop(tx);
+    t.join().unwrap();
+}

tokio-channel/tests/support/mod.rs

@@ -0,0 +1,16 @@
+use futures::Future;
+
+pub trait ForgetExt {
+    fn forget(self);
+}
+
+impl<F> ForgetExt for F
+    where F: Future + Sized + Send + 'static,
+          F::Item: Send,
+          F::Error: Send
+{
+    fn forget(self) {
+        use std::thread;
+        thread::spawn(|| self.wait());
+    }
+}

tokio-codec/CHANGELOG.md

@@ -1,3 +1,7 @@
-# # 0.1.0 (June 13, 2018)
+# 0.1.1 (September 26, 2018)
+
+* Allow setting max line length with `LinesCodec` (#632)
+
+# 0.1.0 (June 13, 2018)
 
 * Initial release (#353)

tokio-codec/Cargo.toml

@@ -3,14 +3,15 @@ name = "tokio-codec"
 
 # When releasing to crates.io:
 # - Update html_root_url.
+# - Update doc URL.
 # - Update CHANGELOG.md.
 # - Create "v0.1.x" git tag.
-version = "0.1.0"
+version = "0.1.1"
 authors = ["Carl Lerche <[email protected]>", "Bryan Burgers <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
-documentation = "https://docs.rs/tokio-codec/0.1"
+documentation = "https://docs.rs/tokio-codec/0.1.1/tokio_codec"
 description = """
 Utilities for encoding and decoding frames.
 """

tokio-codec/src/lib.rs

@@ -1,3 +1,6 @@
+#![deny(missing_docs, missing_debug_implementations, warnings)]
+#![doc(html_root_url = "https://docs.rs/tokio-codec/0.1.1")]
+
 //! Utilities for encoding and decoding frames.
 //!
 //! Contains adapters to go from streams of bytes, [`AsyncRead`] and
@@ -10,9 +13,6 @@
 //! [`Stream`]: #
 //! [transports]: #
 
-#![deny(missing_docs, missing_debug_implementations, warnings)]
-#![doc(html_root_url = "https://docs.rs/tokio-codec/0.1.0")]
-
 extern crate bytes;
 extern crate tokio_io;
 

tokio-codec/src/lines_codec.rs

@@ -1,6 +1,6 @@
 use bytes::{BufMut, BytesMut};
 use tokio_io::_tokio_codec::{Encoder, Decoder};
-use std::{io, str};
+use std::{cmp, io, str, usize};
 
 /// A simple `Codec` implementation that splits up data into lines.
 #[derive(Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
@@ -12,12 +12,93 @@ pub struct LinesCodec {
     // The next time `decode` is called with `abcde\n`, the method will
     // only look at `de\n` before returning.
     next_index: usize,
+
+    /// The maximum length for a given line. If `usize::MAX`, lines will be
+    /// read until a `\n` character is reached.
+    max_length: usize,
+
+    /// Are we currently discarding the remainder of a line which was over
+    /// the length limit?
+    is_discarding: bool,
 }
 
 impl LinesCodec {
     /// Returns a `LinesCodec` for splitting up data into lines.
+    ///
+    /// # Note
+    ///
+    /// The returned `LinesCodec` will not have an upper bound on the length
+    /// of a buffered line. See the documentation for [`new_with_max_length`]
+    /// for information on why this could be a potential security risk.
+    ///
+    /// [`new_with_max_length`]: #method.new_with_max_length
     pub fn new() -> LinesCodec {
-        LinesCodec { next_index: 0 }
+        LinesCodec {
+            next_index: 0,
+            max_length: usize::MAX,
+            is_discarding: false,
+        }
+    }
+
+    /// Returns a `LinesCodec` with a maximum line length limit.
+    ///
+    /// If this is set, calls to `LinesCodec::decode` will return a
+    /// [`LengthError`] when a line exceeds the length limit. Subsequent calls
+    /// will discard up to `limit` bytes from that line until a newline
+    /// character is reached, returning `None` until the line over the limit
+    /// has been fully discarded. After that point, calls to `decode` will
+    /// function as normal.
+    ///
+    /// # Note
+    ///
+    /// Setting a length limit is highly recommended for any `LinesCodec` which
+    /// will be exposed to untrusted input. Otherwise, the size of the buffer
+    /// that holds the line currently being read is unbounded. An attacker could
+    /// exploit this unbounded buffer by sending an unbounded amount of input
+    /// without any `\n` characters, causing unbounded memory consumption.
+    ///
+    /// [`LengthError`]: ../struct.LengthError
+    pub fn new_with_max_length(max_length: usize) -> Self {
+        LinesCodec {
+            max_length,
+            ..LinesCodec::new()
+        }
+    }
+
+    /// Returns the maximum line length when decoding.
+    ///
+    /// ```
+    /// use std::usize;
+    /// use tokio_codec::LinesCodec;
+    ///
+    /// let codec = LinesCodec::new();
+    /// assert_eq!(codec.max_length(), usize::MAX);
+    /// ```
+    /// ```
+    /// use tokio_codec::LinesCodec;
+    ///
+    /// let codec = LinesCodec::new_with_max_length(256);
+    /// assert_eq!(codec.max_length(), 256);
+    /// ```
+    pub fn max_length(&self) -> usize {
+        self.max_length
+    }
+
+    fn discard(&mut self, newline_offset: Option<usize>, read_to: usize, buf: &mut BytesMut) {
+        let discard_to = if let Some(offset) = newline_offset {
+            // If we found a newline, discard up to that offset and
+            // then stop discarding. On the next iteration, we'll try
+            // to read a line normally.
+            self.is_discarding = false;
+            offset + self.next_index + 1
+        } else {
+            // Otherwise, we didn't find a newline, so we'll discard
+            // everything we read. On the next iteration, we'll continue
+            // discarding up to max_len bytes unless we find a newline.
+            read_to
+        };
+        buf.advance(discard_to);
+        self.next_index = 0;
     }
 }
 
@@ -38,22 +119,49 @@ fn without_carriage_return(s: &[u8]) -> &[u8] {
 
 impl Decoder for LinesCodec {
     type Item = String;
+    // TODO: in the next breaking change, this should be changed to a custom
+    // error type that indicates the "max length exceeded" condition better.
     type Error = io::Error;
 
     fn decode(&mut self, buf: &mut BytesMut) -> Result<Option<String>, io::Error> {
-        if let Some(newline_offset) =
-            buf[self.next_index..].iter().position(|b| *b == b'\n')
-        {
-            let newline_index = newline_offset + self.next_index;
-            let line = buf.split_to(newline_index + 1);
-            let line = &line[..line.len()-1];
-            let line = without_carriage_return(line);
-            let line = utf8(line)?;
-            self.next_index = 0;
-            Ok(Some(line.to_string()))
-        } else {
-            self.next_index = buf.len();
-            Ok(None)
+        loop {
+            // Determine how far into the buffer we'll search for a newline. If
+            // there's no max_length set, we'll read to the end of the buffer.
+            let read_to = cmp::min(self.max_length.saturating_add(1), buf.len());
+
+            let newline_offset = buf[self.next_index..read_to]
+                .iter()
+                .position(|b| *b == b'\n');
+
+            if self.is_discarding {
+                self.discard(newline_offset, read_to, buf);
+            } else {
+                return if let Some(offset) = newline_offset {
+                    // Found a line!
+                    let newline_index = offset + self.next_index;
+                    self.next_index = 0;
+                    let line = buf.split_to(newline_index + 1);
+                    let line = &line[..line.len() - 1];
+                    let line = without_carriage_return(line);
+                    let line = utf8(line)?;
+
+                    Ok(Some(line.to_string()))
+                } else if buf.len() > self.max_length {
+                    // Reached the maximum length without finding a
+                    // newline, return an error and start discarding on the
+                    // next call.
+                    self.is_discarding = true;
+                    Err(io::Error::new(
+                        io::ErrorKind::Other,
+                        "line length limit exceeded"
+                    ))
+                } else {
+                    // We didn't find a line or reach the length limit, so the next
+                    // call will resume searching at the current offset.
+                    self.next_index = read_to;
+                    Ok(None)
+                };
+            }
         }
     }
 

tokio-codec/tests/codecs.rs

@@ -55,6 +55,116 @@ fn lines_decoder() {
     assert_eq!(None, codec.decode_eof(buf).unwrap());
 }
 
+#[test]
+fn lines_decoder_max_length() {
+    const MAX_LENGTH: usize = 6;
+
+    let mut codec = LinesCodec::new_with_max_length(MAX_LENGTH);
+    let buf = &mut BytesMut::new();
+
+    buf.reserve(200);
+    buf.put("line 1 is too long\nline 2\nline 3\r\nline 4\n\r\n\r");
+
+    assert!(codec.decode(buf).is_err());
+
+    let line = codec.decode(buf).unwrap().unwrap();
+    assert!(line.len() <= MAX_LENGTH, "{:?}.len() <= {:?}", line, MAX_LENGTH);
+    assert_eq!("line 2", line);
+
+    assert!(codec.decode(buf).is_err());
+
+    let line = codec.decode(buf).unwrap().unwrap();
+    assert!(line.len() <= MAX_LENGTH, "{:?}.len() <= {:?}", line, MAX_LENGTH);
+    assert_eq!("line 4", line);
+
+    let line = codec.decode(buf).unwrap().unwrap();
+    assert!(line.len() <= MAX_LENGTH, "{:?}.len() <= {:?}", line, MAX_LENGTH);
+    assert_eq!("", line);
+
+    assert_eq!(None, codec.decode(buf).unwrap());
+    assert_eq!(None, codec.decode_eof(buf).unwrap());
+    buf.put("k");
+    assert_eq!(None, codec.decode(buf).unwrap());
+
+    let line = codec.decode_eof(buf).unwrap().unwrap();
+    assert!(line.len() <= MAX_LENGTH, "{:?}.len() <= {:?}", line, MAX_LENGTH);
+    assert_eq!("\rk", line);
+
+    assert_eq!(None, codec.decode(buf).unwrap());
+    assert_eq!(None, codec.decode_eof(buf).unwrap());
+
+    // Line that's one character too long. This could cause an out of bounds
+    // error if we peek at the next characters using slice indexing.
+    // buf.put("aaabbbc");
+    // assert!(codec.decode(buf).is_err());
+}
+
+#[test]
+fn lines_decoder_max_length_underrun() {
+    const MAX_LENGTH: usize = 6;
+
+    let mut codec = LinesCodec::new_with_max_length(MAX_LENGTH);
+    let buf = &mut BytesMut::new();
+
+    buf.reserve(200);
+    buf.put("line ");
+    assert_eq!(None, codec.decode(buf).unwrap());
+    buf.put("too l");
+    assert!(codec.decode(buf).is_err());
+    buf.put("ong\n");
+    assert_eq!(None, codec.decode(buf).unwrap());
+
+    buf.put("line 2");
+    assert_eq!(None, codec.decode(buf).unwrap());
+    buf.put("\n");
+    assert_eq!("line 2", codec.decode(buf).unwrap().unwrap());
+}
+
+#[test]
+fn lines_decoder_max_length_bursts() {
+    const MAX_LENGTH: usize = 10;
+
+    let mut codec = LinesCodec::new_with_max_length(MAX_LENGTH);
+    let buf = &mut BytesMut::new();
+
+    buf.reserve(200);
+    buf.put("line ");
+    assert_eq!(None, codec.decode(buf).unwrap());
+    buf.put("too l");
+    assert_eq!(None, codec.decode(buf).unwrap());
+    buf.put("ong\n");
+    assert!(codec.decode(buf).is_err());
+}
+
+#[test]
+fn lines_decoder_max_length_big_burst() {
+    const MAX_LENGTH: usize = 10;
+
+    let mut codec = LinesCodec::new_with_max_length(MAX_LENGTH);
+    let buf = &mut BytesMut::new();
+
+    buf.reserve(200);
+    buf.put("line ");
+    assert_eq!(None, codec.decode(buf).unwrap());
+    buf.put("too long!\n");
+    assert!(codec.decode(buf).is_err());
+}
+
+#[test]
+fn lines_decoder_max_length_newline_between_decodes() {
+    const MAX_LENGTH: usize = 5;
+
+    let mut codec = LinesCodec::new_with_max_length(MAX_LENGTH);
+    let buf = &mut BytesMut::new();
+
+    buf.reserve(200);
+    buf.put("hello");
+    assert_eq!(None, codec.decode(buf).unwrap());
+
+    buf.put("\nworld");
+    assert_eq!("hello", codec.decode(buf).unwrap().unwrap());
+}
+
 #[test]
 fn lines_encoder() {
     let mut codec = LinesCodec::new();