chore: prepare Tokio v1.37.0 (#6435)

Fixes: #4638

.cargo/audit.toml

@@ -1,8 +0,0 @@
-# See https://github.com/rustsec/rustsec/blob/59e1d2ad0b9cbc6892c26de233d4925074b4b97b/cargo-audit/audit.toml.example for example.
-
-[advisories]
-ignore = [
-    # We depend on nix 0.22 only via mio-aio, a dev-dependency.
-    # https://github.com/tokio-rs/tokio/pull/4255#issuecomment-974786349
-    "RUSTSEC-2021-0119",
-]

.circleci/config.yml

@@ -2,7 +2,7 @@ version: 2.1
 jobs:
   test-arm:
     machine:
-      image: ubuntu-2004:202101-01
+      image: default
     resource_class: arm.medium
     environment:
       # Change to pin rust version

.cirrus.yml

@@ -1,10 +1,10 @@
 only_if: $CIRRUS_TAG == '' && ($CIRRUS_PR != '' || $CIRRUS_BRANCH == 'master' || $CIRRUS_BRANCH =~ 'tokio-.*')
 auto_cancellation: $CIRRUS_BRANCH != 'master' && $CIRRUS_BRANCH !=~ 'tokio-.*'
 freebsd_instance:
-  image_family: freebsd-13-1
+  image_family: freebsd-14-0
 env:
   RUST_STABLE: stable
-  RUST_NIGHTLY: nightly-2022-10-25
+  RUST_NIGHTLY: nightly-2023-10-21
   RUSTFLAGS: -D warnings
 
 # Test FreeBSD in a full VM on cirrus-ci.com.  Test the i686 target too, in the

.clippy.toml

@@ -1 +0,0 @@
-msrv = "1.56"

.github/labeler.yml

@@ -1,8 +1,28 @@
 
-R-loom:
+R-loom-sync:
 - tokio/src/sync/*
 - tokio/src/sync/**/*
-- tokio-util/src/sync/*
-- tokio-util/src/sync/**/*
-- tokio/src/runtime/*
-- tokio/src/runtime/**/*
+
+R-loom-time-driver:
+- tokio/src/runtime/time/*
+- tokio/src/runtime/time/**/*
+
+R-loom-current-thread:
+- tokio/src/runtime/scheduler/*
+- tokio/src/runtime/scheduler/current_thread/*
+- tokio/src/runtime/task/*
+- tokio/src/runtime/task/**
+
+R-loom-multi-thread:
+- tokio/src/runtime/scheduler/*
+- tokio/src/runtime/scheduler/multi_thread/*
+- tokio/src/runtime/scheduler/multi_thread/**
+- tokio/src/runtime/task/*
+- tokio/src/runtime/task/**
+
+R-loom-multi-thread-alt:
+- tokio/src/runtime/scheduler/*
+- tokio/src/runtime/scheduler/multi_thread_alt/*
+- tokio/src/runtime/scheduler/multi_thread_alt/**
+- tokio/src/runtime/task/*
+- tokio/src/runtime/task/**

.github/workflows/audit.yml

@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     if: "!contains(github.event.head_commit.message, 'ci skip')"
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Audit Check
         # https://github.com/rustsec/audit-check/issues/2

.github/workflows/labeler.yml

@@ -4,6 +4,10 @@ on:
 
 # See .github/labeler.yml file
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
 permissions:
   contents: read
 

.github/workflows/loom.yml

@@ -7,8 +7,14 @@ on:
 
 name: Loom
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
 env:
-  RUSTFLAGS: -Dwarnings
+  RUSTFLAGS: -Dwarnings --cfg loom --cfg tokio_unstable -C debug_assertions
+  LOOM_MAX_PREEMPTIONS: 2
+  LOOM_MAX_BRANCHES: 10000
   RUST_BACKTRACE: 1
   # Change to specific Rust release to pin
   rust_stable: stable
@@ -17,38 +23,100 @@ permissions:
   contents: read
 
 jobs:
-  loom:
-    name: loom
+  loom-sync:
+    name: loom tokio::sync
     # base_ref is null when it's not a pull request
-    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom') || (github.base_ref == null))
+    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom-sync') || (github.base_ref == null))
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: dtolnay/rust-toolchain@master
+        with:
+            toolchain: ${{ env.rust_stable }}
+      - uses: Swatinem/rust-cache@v2
+      - name: run tests
+        run: cargo test --lib --release --features full -- --nocapture sync::tests
+        working-directory: tokio
+
+  loom-time-driver:
+    name: loom time driver
+    # base_ref is null when it's not a pull request
+    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom-time-driver') || (github.base_ref == null))
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: dtolnay/rust-toolchain@master
+        with:
+            toolchain: ${{ env.rust_stable }}
+      - uses: Swatinem/rust-cache@v2
+      - name: run tests
+        run: cargo test --lib --release --features full -- --nocapture runtime::time::tests
+        working-directory: tokio
+
+  loom-current-thread:
+    name: loom current-thread scheduler
+    # base_ref is null when it's not a pull request
+    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom-current-thread') || (github.base_ref == null))
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: dtolnay/rust-toolchain@master
+        with:
+            toolchain: ${{ env.rust_stable }}
+      - uses: Swatinem/rust-cache@v2
+      - name: run tests
+        run: cargo test --lib --release --features full -- --nocapture loom_current_thread
+        working-directory: tokio
+
+  loom-multi-thread:
+    name: loom multi-thread scheduler
+    # base_ref is null when it's not a pull request
+    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom-multi-thread') || (github.base_ref == null))
     runs-on: ubuntu-latest
     strategy:
       matrix:
         include:
-          - scope: --skip loom_pool
-            max_preemptions: 2
-          - scope: loom_pool::group_a
-            max_preemptions: 2
-          - scope: loom_pool::group_b
-            max_preemptions: 2
-          - scope: loom_pool::group_c
-            max_preemptions: 2
-          - scope: loom_pool::group_d
-            max_preemptions: 2
-          - scope: time::driver
-            max_preemptions: 2
+          - scope: loom_multi_thread::group_a
+          - scope: loom_multi_thread::group_b
+          - scope: loom_multi_thread::group_c
+          - scope: loom_multi_thread::group_d
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Install Rust ${{ env.rust_stable }}
         uses: dtolnay/rust-toolchain@master
         with:
             toolchain: ${{ env.rust_stable }}
       - uses: Swatinem/rust-cache@v2
       - name: loom ${{ matrix.scope }}
-        run: cargo test --lib --release --features full -- --nocapture $SCOPE
+        run: cargo test --lib --release --features full -- $SCOPE
+        working-directory: tokio
+        env:
+          SCOPE: ${{ matrix.scope }}
+
+  loom-multi-thread-alt:
+    name: loom ALT multi-thread scheduler
+    # base_ref is null when it's not a pull request
+    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom-multi-thread-alt') || (github.base_ref == null))
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include:
+          - scope: loom_multi_thread_alt::group_a
+          - scope: loom_multi_thread_alt::group_b
+          - scope: loom_multi_thread_alt::group_c
+          - scope: loom_multi_thread_alt::group_d
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: dtolnay/rust-toolchain@master
+        with:
+            toolchain: ${{ env.rust_stable }}
+      - uses: Swatinem/rust-cache@v2
+      - name: loom ${{ matrix.scope }}
+        run: cargo test --lib --release --features full -- $SCOPE
         working-directory: tokio
         env:
-          RUSTFLAGS: --cfg loom --cfg tokio_unstable -Dwarnings -C debug-assertions
-          LOOM_MAX_PREEMPTIONS: ${{ matrix.max_preemptions }}
-          LOOM_MAX_BRANCHES: 10000
           SCOPE: ${{ matrix.scope }}

.github/workflows/pr-audit.yml

@@ -8,6 +8,10 @@ on:
     paths:
       - '**/Cargo.toml'
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
 permissions:
   contents: read
 
@@ -16,7 +20,7 @@ jobs:
     runs-on: ubuntu-latest
     if: "!contains(github.event.head_commit.message, 'ci skip')"
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Install cargo-audit
         run: cargo install cargo-audit

.github/workflows/stress-test.yml

@@ -5,6 +5,10 @@ on:
     branches:
       - master
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
 env:
   RUSTFLAGS: -Dwarnings
   RUST_BACKTRACE: 1
@@ -23,19 +27,19 @@ jobs:
         stress-test:
           - simple_echo_tcp
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Install Rust ${{ env.rust_stable }}
         uses: dtolnay/rust-toolchain@master
         with:
             toolchain: ${{ env.rust_stable }}
-      - uses: Swatinem/rust-cache@v2
       - name: Install Valgrind
         uses: taiki-e/install-action@valgrind
 
+      - uses: Swatinem/rust-cache@v2
       # Compiles each of the stress test examples.
       - name: Compile stress test examples
         run: cargo build -p stress-test --release --example ${{ matrix.stress-test }}
 
       # Runs each of the examples using Valgrind. Detects leaks and displays them.
       - name: Run valgrind
-        run: valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all ./target/release/examples/${{ matrix.stress-test }}
+        run: valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all --fair-sched=yes ./target/release/examples/${{ matrix.stress-test }}

CONTRIBUTING.md

@@ -149,7 +149,7 @@ When updating this, also update:
 -->
 
 ```
-cargo +1.65.0 clippy --all --tests --all-features
+cargo +1.76 clippy --all --tests --all-features
 ```
 
 When building documentation normally, the markers that list the features
@@ -173,10 +173,10 @@ command below instead:
 
 ```
 # Mac or Linux
-rustfmt --check --edition 2018 $(git ls-files '*.rs')
+rustfmt --check --edition 2021 $(git ls-files '*.rs')
 
 # Powershell
-Get-ChildItem . -Filter "*.rs" -Recurse | foreach { rustfmt --check --edition 2018 $_.FullName }
+Get-ChildItem . -Filter "*.rs" -Recurse | foreach { rustfmt --check --edition 2021 $_.FullName }
 ```
 The `--check` argument prints the things that need to be fixed. If you remove
 it, `rustfmt` will update your files locally instead.
@@ -184,9 +184,11 @@ it, `rustfmt` will update your files locally instead.
 You can run loom tests with
 ```
 cd tokio # tokio crate in workspace
-LOOM_MAX_PREEMPTIONS=1 RUSTFLAGS="--cfg loom" \
+LOOM_MAX_PREEMPTIONS=1 LOOM_MAX_BRANCHES=10000 RUSTFLAGS="--cfg loom -C debug_assertions" \
     cargo test --lib --release --features full -- --test-threads=1 --nocapture
 ```
+Additionally, you can also add `--cfg tokio_unstable` to the `RUSTFLAGS` environment variable to
+run loom tests that test unstable features. 
 
 You can run miri tests with
 ```
@@ -194,6 +196,24 @@ MIRIFLAGS="-Zmiri-disable-isolation -Zmiri-tag-raw-pointers" \
     cargo +nightly miri test --features full --lib
 ```
 
+### Performing spellcheck on tokio codebase
+
+You can perform spell-check on tokio codebase. For details of how to use the spellcheck tool, feel free to visit
+https://github.com/drahnr/cargo-spellcheck
+```
+# First install the spell-check plugin
+cargo install --locked cargo-spellcheck
+
+# Then run the cargo spell check command
+cargo spellcheck check
+```
+
+if the command rejects a word, you should backtick the rejected word if it's code related. If not, the 
+rejected word should be put into `spellcheck.dic` file. 
+
+Note that when you add a word into the file, you should also update the first line which tells the spellcheck tool
+the total number of words included in the file
+
 ### Tests
 
 If the change being proposed alters code (as opposed to only documentation for
@@ -230,7 +250,7 @@ integration tests in the crate and follow the style.
 
 Some of our crates include a set of fuzz tests, this will be marked by a
 directory `fuzz`. It is a good idea to run fuzz tests after each change.
-To get started with fuzz testing you'll need to install 
+To get started with fuzz testing you'll need to install
 [cargo-fuzz](https://github.com/rust-fuzz/cargo-fuzz).
 
 `cargo install cargo-fuzz`
@@ -327,6 +347,29 @@ example would explicitly use `Timeout::new`. For example:
 /// # }
 ```
 
+### Benchmarks
+
+You can run benchmarks locally for the changes you've made to the tokio codebase.
+Tokio currently uses [Criterion](https://github.com/bheisler/criterion.rs) as its benchmarking tool. To run a benchmark
+against the changes you have made, for example, you can run;
+
+```bash
+cd benches
+
+# Run all benchmarks.
+cargo bench
+
+# Run all tests in the `benches/fs.rs` file
+cargo bench --bench fs
+
+# Run the `async_read_buf` benchmark in `benches/fs.rs` specifically.
+cargo bench async_read_buf
+
+# After running benches, you can check the statistics under `tokio/target/criterion/`
+```
+
+You can also refer to Criterion docs for additional options and details.
+
 ### Commits
 
 It is a recommended best practice to keep your changes as logically grouped as
@@ -350,14 +393,16 @@ A good commit message should describe what changed and why.
     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.
+  * start with an imperative verb
+  * not have a period at the end
+  * be prefixed with the name of the module being changed; usually this is the
+    same as the M-* label on the PR
 
   Examples:
 
-  * timer: introduce `Timeout` and deprecate `Deadline`
-  * export `Encoder`, `Decoder`, `Framed*` from tokio_codec
+  * time: introduce `Timeout` and deprecate `Deadline`
+  * codec: export `Encoder`, `Decoder`, `Framed*`
+  * ci: fix the FreeBSD ci configuration
 
 2. Keep the second line blank.
 3. Wrap all other lines at 72 columns (except for long URLs).
@@ -374,7 +419,7 @@ A good commit message should describe what changed and why.
 Sample complete commit message:
 
 ```txt
-subcrate: explain the commit in one line
+module: 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
@@ -678,4 +723,4 @@ When releasing a new version of a crate, follow these steps:
 [unit-tests]: https://doc.rust-lang.org/rust-by-example/testing/unit_testing.html
 [integration-tests]: https://doc.rust-lang.org/rust-by-example/testing/integration_testing.html
 [documentation-tests]: https://doc.rust-lang.org/rust-by-example/testing/doc_testing.html
-[conditional-compilation]: https://doc.rust-lang.org/reference/conditional-compilation.html
+[conditional-compilation]: https://doc.rust-lang.org/reference/conditional-compilation.html

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-
+resolver = "2"
 members = [
   "tokio",
   "tokio-macros",
@@ -14,3 +14,7 @@ members = [
   "tests-build",
   "tests-integration",
 ]
+
+[workspace.metadata.spellcheck]
+config = "spellcheck.toml"
+

README.md

@@ -56,7 +56,7 @@ Make sure you activated the full features of the tokio crate on Cargo.toml:
 
 ```toml
 [dependencies]
-tokio = { version = "1.28.2", features = ["full"] }
+tokio = { version = "1.37.0", features = ["full"] }
 ```
 Then, on your main.rs:
 
@@ -132,6 +132,8 @@ project.
 In addition to the crates in this repository, the Tokio project also maintains
 several other libraries, including:
 
+* [`axum`]: A web application framework that focuses on ergonomics and modularity.
+
 * [`hyper`]: A fast and correct HTTP/1.1 and HTTP/2 implementation for Rust.
 
 * [`tonic`]: A gRPC over HTTP/2 implementation focused on high performance, interoperability, and flexibility.
@@ -142,21 +144,18 @@ several other libraries, including:
 
 * [`tracing`] (formerly `tokio-trace`): A framework for application-level tracing and async-aware diagnostics.
 
-* [`rdbc`]: A Rust database connectivity library for MySQL, Postgres and SQLite.
-
-* [`mio`]: A low-level, cross-platform abstraction over OS I/O APIs that powers
-  `tokio`.
+* [`mio`]: A low-level, cross-platform abstraction over OS I/O APIs that powers `tokio`.
 
 * [`bytes`]: Utilities for working with bytes, including efficient byte buffers.
 
-* [`loom`]: A testing tool for concurrent Rust code
+* [`loom`]: A testing tool for concurrent Rust code.
 
+[`axum`]: https://github.com/tokio-rs/axum
 [`warp`]: https://github.com/seanmonstar/warp
 [`hyper`]: https://github.com/hyperium/hyper
 [`tonic`]: https://github.com/hyperium/tonic
 [`tower`]: https://github.com/tower-rs/tower
 [`loom`]: https://github.com/tokio-rs/loom
-[`rdbc`]: https://github.com/tokio-rs/rdbc
 [`tracing`]: https://github.com/tokio-rs/tracing
 [`mio`]: https://github.com/tokio-rs/mio
 [`bytes`]: https://github.com/tokio-rs/bytes
@@ -187,12 +186,13 @@ When updating this, also update:
 
 Tokio will keep a rolling MSRV (minimum supported rust version) policy of **at
 least** 6 months. When increasing the MSRV, the new Rust version must have been
-released at least six months ago. The current MSRV is 1.56.0.
+released at least six months ago. The current MSRV is 1.63.
 
 Note that the MSRV is not increased automatically, and only as part of a minor
 release. The MSRV history for past minor releases can be found below:
 
- * 1.27 to now - Rust 1.56
+ * 1.30 to now - Rust 1.63
+ * 1.27 to 1.29 - Rust 1.56
  * 1.17 to 1.26 - Rust 1.49
  * 1.15 to 1.16 - Rust 1.46
  * 1.0 to 1.14 - Rust 1.45
@@ -215,21 +215,28 @@ warrants a patch release with a fix for the bug, it will be backported and
 released as a new patch release for each LTS minor version. Our current LTS
 releases are:
 
- * `1.18.x` - LTS release until June 2023. (MSRV 1.49)
- * `1.20.x` - LTS release until September 2023. (MSRV 1.49)
- * `1.25.x` - LTS release until March 2024. (MSRV 1.49)
+ * `1.32.x` - LTS release until September 2024. (MSRV 1.63)
+ * `1.36.x` - LTS release until March 2025. (MSRV 1.63)
 
 Each LTS release will continue to receive backported fixes for at least a year.
 If you wish to use a fixed minor release in your project, we recommend that you
 use an LTS release.
 
 To use a fixed minor version, you can specify the version with a tilde. For
-example, to specify that you wish to use the newest `1.18.x` patch release, you
+example, to specify that you wish to use the newest `1.32.x` patch release, you
 can use the following dependency specification:
 ```text
-tokio = { version = "~1.18", features = [...] }
+tokio = { version = "~1.32", features = [...] }
 ```
 
+### Previous LTS releases
+
+ * `1.8.x` - LTS release until February 2022.
+ * `1.14.x` - LTS release until June 2022.
+ * `1.18.x` - LTS release until June 2023.
+ * `1.20.x` - LTS release until September 2023.
+ * `1.25.x` - LTS release until March 2024.
+
 ## License
 
 This project is licensed under the [MIT license].

benches/Cargo.toml

@@ -2,16 +2,17 @@
 name = "benches"
 version = "0.0.0"
 publish = false
-edition = "2018"
+edition = "2021"
 
 [features]
 test-util = ["tokio/test-util"]
 
 [dependencies]
 tokio = { version = "1.5.0", path = "../tokio", features = ["full"] }
-bencher = "0.1.5"
+criterion = "0.5.1"
 rand = "0.8"
 rand_chacha = "0.3"
+num_cpus = "1.16.0"
 
 [dev-dependencies]
 tokio-util = { version = "0.7.0", path = "../tokio-util", features = ["full"] }
@@ -25,6 +26,11 @@ name = "spawn"
 path = "spawn.rs"
 harness = false
 
+[[bench]]
+name = "sync_broadcast"
+path = "sync_broadcast.rs"
+harness = false
+
 [[bench]]
 name = "sync_mpsc"
 path = "sync_mpsc.rs"

benches/copy.rs

@@ -1,4 +1,4 @@
-use bencher::{benchmark_group, benchmark_main, Bencher};
+use criterion::{criterion_group, criterion_main, Criterion};
 
 use rand::{Rng, SeedableRng};
 use rand_chacha::ChaCha20Rng;
@@ -29,7 +29,7 @@ const WRITE_SERVICE_PERIOD: Duration = Duration::from_millis(20);
 // because another writer claimed the buffer space
 const PROBABILITY_FLUSH_WAIT: f64 = 0.1;
 
-/// A slow writer that aims to simulate HDD behaviour under heavy load.
+/// A slow writer that aims to simulate HDD behavior under heavy load.
 ///
 /// There is a limited buffer, which is fully drained on the next write after
 /// a time limit is reached. Flush waits for the time limit to be reached
@@ -64,7 +64,7 @@ impl SlowHddWriter {
     ) -> std::task::Poll<Result<(), std::io::Error>> {
         // If we hit a service interval, the buffer can be cleared
         let res = self.service_intervals.poll_tick(cx).map(|_| Ok(()));
-        if let Poll::Ready(_) = res {
+        if res.is_ready() {
             self.buffer_used = 0;
         }
         res
@@ -123,7 +123,7 @@ impl AsyncWrite for SlowHddWriter {
         cx: &mut std::task::Context<'_>,
         bufs: &[std::io::IoSlice<'_>],
     ) -> std::task::Poll<Result<usize, std::io::Error>> {
-        let writeable = bufs.into_iter().fold(0, |acc, buf| acc + buf.len());
+        let writeable = bufs.iter().fold(0, |acc, buf| acc + buf.len());
         self.write_bytes(cx, writeable)
     }
 
@@ -174,65 +174,77 @@ fn rt() -> tokio::runtime::Runtime {
         .unwrap()
 }
 
-fn copy_mem_to_mem(b: &mut Bencher) {
+fn copy_mem_to_mem(c: &mut Criterion) {
     let rt = rt();
 
-    b.iter(|| {
-        let task = || async {
-            let mut source = repeat(0).take(SOURCE_SIZE);
-            let mut dest = Vec::new();
-            copy(&mut source, &mut dest).await.unwrap();
-        };
+    c.bench_function("copy_mem_to_mem", |b| {
+        b.iter(|| {
+            let task = || async {
+                let mut source = repeat(0).take(SOURCE_SIZE);
+                let mut dest = Vec::new();
+                copy(&mut source, &mut dest).await.unwrap();
+            };
 
-        rt.block_on(task());
-    })
+            rt.block_on(task());
+        })
+    });
 }
 
-fn copy_mem_to_slow_hdd(b: &mut Bencher) {
+fn copy_mem_to_slow_hdd(c: &mut Criterion) {
     let rt = rt();
 
-    b.iter(|| {
-        let task = || async {
-            let mut source = repeat(0).take(SOURCE_SIZE);
-            let mut dest = SlowHddWriter::new(WRITE_SERVICE_PERIOD, WRITE_BUFFER);
-            copy(&mut source, &mut dest).await.unwrap();
-        };
+    c.bench_function("copy_mem_to_slow_hdd", |b| {
+        b.iter(|| {
+            let task = || async {
+                let mut source = repeat(0).take(SOURCE_SIZE);
+                let mut dest = SlowHddWriter::new(WRITE_SERVICE_PERIOD, WRITE_BUFFER);
+                copy(&mut source, &mut dest).await.unwrap();
+            };
 
-        rt.block_on(task());
-    })
+            rt.block_on(task());
+        })
+    });
 }
 
-fn copy_chunk_to_mem(b: &mut Bencher) {
+fn copy_chunk_to_mem(c: &mut Criterion) {
     let rt = rt();
-    b.iter(|| {
-        let task = || async {
-            let mut source = ChunkReader::new(CHUNK_SIZE, READ_SERVICE_PERIOD).take(SOURCE_SIZE);
-            let mut dest = Vec::new();
-            copy(&mut source, &mut dest).await.unwrap();
-        };
 
-        rt.block_on(task());
-    })
+    c.bench_function("copy_chunk_to_mem", |b| {
+        b.iter(|| {
+            let task = || async {
+                let mut source =
+                    ChunkReader::new(CHUNK_SIZE, READ_SERVICE_PERIOD).take(SOURCE_SIZE);
+                let mut dest = Vec::new();
+                copy(&mut source, &mut dest).await.unwrap();
+            };
+
+            rt.block_on(task());
+        })
+    });
 }
 
-fn copy_chunk_to_slow_hdd(b: &mut Bencher) {
+fn copy_chunk_to_slow_hdd(c: &mut Criterion) {
     let rt = rt();
-    b.iter(|| {
-        let task = || async {
-            let mut source = ChunkReader::new(CHUNK_SIZE, READ_SERVICE_PERIOD).take(SOURCE_SIZE);
-            let mut dest = SlowHddWriter::new(WRITE_SERVICE_PERIOD, WRITE_BUFFER);
-            copy(&mut source, &mut dest).await.unwrap();
-        };
 
-        rt.block_on(task());
-    })
+    c.bench_function("copy_chunk_to_slow_hdd", |b| {
+        b.iter(|| {
+            let task = || async {
+                let mut source =
+                    ChunkReader::new(CHUNK_SIZE, READ_SERVICE_PERIOD).take(SOURCE_SIZE);
+                let mut dest = SlowHddWriter::new(WRITE_SERVICE_PERIOD, WRITE_BUFFER);
+                copy(&mut source, &mut dest).await.unwrap();
+            };
+
+            rt.block_on(task());
+        })
+    });
 }
 
-benchmark_group!(
+criterion_group!(
     copy_bench,
     copy_mem_to_mem,
     copy_mem_to_slow_hdd,
     copy_chunk_to_mem,
     copy_chunk_to_slow_hdd,
 );
-benchmark_main!(copy_bench);
+criterion_main!(copy_bench);

benches/fs.rs

@@ -6,7 +6,7 @@ use tokio::fs::File;
 use tokio::io::AsyncReadExt;
 use tokio_util::codec::{BytesCodec, FramedRead /*FramedWrite*/};
 
-use bencher::{benchmark_group, benchmark_main, Bencher};
+use criterion::{criterion_group, criterion_main, Criterion};
 
 use std::fs::File as StdFile;
 use std::io::Read as StdRead;
@@ -23,81 +23,90 @@ const BLOCK_COUNT: usize = 1_000;
 const BUFFER_SIZE: usize = 4096;
 const DEV_ZERO: &str = "/dev/zero";
 
-fn async_read_codec(b: &mut Bencher) {
+fn async_read_codec(c: &mut Criterion) {
     let rt = rt();
 
-    b.iter(|| {
-        let task = || async {
-            let file = File::open(DEV_ZERO).await.unwrap();
-            let mut input_stream = FramedRead::with_capacity(file, BytesCodec::new(), BUFFER_SIZE);
+    c.bench_function("async_read_codec", |b| {
+        b.iter(|| {
+            let task = || async {
+                let file = File::open(DEV_ZERO).await.unwrap();
+                let mut input_stream =
+                    FramedRead::with_capacity(file, BytesCodec::new(), BUFFER_SIZE);
 
-            for _i in 0..BLOCK_COUNT {
-                let _bytes = input_stream.next().await.unwrap();
-            }
-        };
-
-        rt.block_on(task());
-    });
-}
-
-fn async_read_buf(b: &mut Bencher) {
-    let rt = rt();
-
-    b.iter(|| {
-        let task = || async {
-            let mut file = File::open(DEV_ZERO).await.unwrap();
-            let mut buffer = [0u8; BUFFER_SIZE];
-
-            for _i in 0..BLOCK_COUNT {
-                let count = file.read(&mut buffer).await.unwrap();
-                if count == 0 {
-                    break;
+                for _i in 0..BLOCK_COUNT {
+                    let _bytes = input_stream.next().await.unwrap();
                 }
-            }
-        };
+            };
 
-        rt.block_on(task());
+            rt.block_on(task());
+        })
     });
 }
 
-fn async_read_std_file(b: &mut Bencher) {
+fn async_read_buf(c: &mut Criterion) {
     let rt = rt();
 
-    let task = || async {
-        let mut file = tokio::task::block_in_place(|| Box::pin(StdFile::open(DEV_ZERO).unwrap()));
+    c.bench_function("async_read_buf", |b| {
+        b.iter(|| {
+            let task = || async {
+                let mut file = File::open(DEV_ZERO).await.unwrap();
+                let mut buffer = [0u8; BUFFER_SIZE];
 
-        for _i in 0..BLOCK_COUNT {
+                for _i in 0..BLOCK_COUNT {
+                    let count = file.read(&mut buffer).await.unwrap();
+                    if count == 0 {
+                        break;
+                    }
+                }
+            };
+
+            rt.block_on(task());
+        });
+    });
+}
+
+fn async_read_std_file(c: &mut Criterion) {
+    let rt = rt();
+
+    c.bench_function("async_read_std_file", |b| {
+        b.iter(|| {
+            let task = || async {
+                let mut file =
+                    tokio::task::block_in_place(|| Box::pin(StdFile::open(DEV_ZERO).unwrap()));
+
+                for _i in 0..BLOCK_COUNT {
+                    let mut buffer = [0u8; BUFFER_SIZE];
+                    let mut file_ref = file.as_mut();
+
+                    tokio::task::block_in_place(move || {
+                        file_ref.read_exact(&mut buffer).unwrap();
+                    });
+                }
+            };
+
+            rt.block_on(task());
+        });
+    });
+}
+
+fn sync_read(c: &mut Criterion) {
+    c.bench_function("sync_read", |b| {
+        b.iter(|| {
+            let mut file = StdFile::open(DEV_ZERO).unwrap();
             let mut buffer = [0u8; BUFFER_SIZE];
-            let mut file_ref = file.as_mut();
 
-            tokio::task::block_in_place(move || {
-                file_ref.read_exact(&mut buffer).unwrap();
-            });
-        }
-    };
-
-    b.iter(|| {
-        rt.block_on(task());
+            for _i in 0..BLOCK_COUNT {
+                file.read_exact(&mut buffer).unwrap();
+            }
+        })
     });
 }
 
-fn sync_read(b: &mut Bencher) {
-    b.iter(|| {
-        let mut file = StdFile::open(DEV_ZERO).unwrap();
-        let mut buffer = [0u8; BUFFER_SIZE];
-
-        for _i in 0..BLOCK_COUNT {
-            file.read_exact(&mut buffer).unwrap();
-        }
-    });
-}
-
-benchmark_group!(
+criterion_group!(
     file,
     async_read_std_file,
     async_read_buf,
     async_read_codec,
     sync_read
 );
-
-benchmark_main!(file);
+criterion_main!(file);

benches/rt_current_thread.rs

@@ -4,46 +4,50 @@
 
 use tokio::runtime::{self, Runtime};
 
-use bencher::{benchmark_group, benchmark_main, Bencher};
+use criterion::{criterion_group, criterion_main, Criterion};
 
 const NUM_SPAWN: usize = 1_000;
 
-fn spawn_many_local(b: &mut Bencher) {
+fn rt_curr_spawn_many_local(c: &mut Criterion) {
     let rt = rt();
     let mut handles = Vec::with_capacity(NUM_SPAWN);
 
-    b.iter(|| {
-        rt.block_on(async {
-            for _ in 0..NUM_SPAWN {
-                handles.push(tokio::spawn(async move {}));
-            }
+    c.bench_function("spawn_many_local", |b| {
+        b.iter(|| {
+            rt.block_on(async {
+                for _ in 0..NUM_SPAWN {
+                    handles.push(tokio::spawn(async move {}));
+                }
 
-            for handle in handles.drain(..) {
-                handle.await.unwrap();
-            }
-        });
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
     });
 }
 
-fn spawn_many_remote_idle(b: &mut Bencher) {
+fn rt_curr_spawn_many_remote_idle(c: &mut Criterion) {
     let rt = rt();
     let rt_handle = rt.handle();
     let mut handles = Vec::with_capacity(NUM_SPAWN);
 
-    b.iter(|| {
-        for _ in 0..NUM_SPAWN {
-            handles.push(rt_handle.spawn(async {}));
-        }
-
-        rt.block_on(async {
-            for handle in handles.drain(..) {
-                handle.await.unwrap();
+    c.bench_function("spawn_many_remote_idle", |b| {
+        b.iter(|| {
+            for _ in 0..NUM_SPAWN {
+                handles.push(rt_handle.spawn(async {}));
             }
-        });
+
+            rt.block_on(async {
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
     });
 }
 
-fn spawn_many_remote_busy(b: &mut Bencher) {
+fn rt_curr_spawn_many_remote_busy(c: &mut Criterion) {
     let rt = rt();
     let rt_handle = rt.handle();
     let mut handles = Vec::with_capacity(NUM_SPAWN);
@@ -56,16 +60,18 @@ fn spawn_many_remote_busy(b: &mut Bencher) {
         iter()
     });
 
-    b.iter(|| {
-        for _ in 0..NUM_SPAWN {
-            handles.push(rt_handle.spawn(async {}));
-        }
-
-        rt.block_on(async {
-            for handle in handles.drain(..) {
-                handle.await.unwrap();
+    c.bench_function("spawn_many_remote_busy", |b| {
+        b.iter(|| {
+            for _ in 0..NUM_SPAWN {
+                handles.push(rt_handle.spawn(async {}));
             }
-        });
+
+            rt.block_on(async {
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
     });
 }
 
@@ -73,11 +79,11 @@ fn rt() -> Runtime {
     runtime::Builder::new_current_thread().build().unwrap()
 }
 
-benchmark_group!(
-    scheduler,
-    spawn_many_local,
-    spawn_many_remote_idle,
-    spawn_many_remote_busy
+criterion_group!(
+    rt_curr_scheduler,
+    rt_curr_spawn_many_local,
+    rt_curr_spawn_many_remote_idle,
+    rt_curr_spawn_many_remote_busy
 );
 
-benchmark_main!(scheduler);
+criterion_main!(rt_curr_scheduler);

benches/rt_multi_threaded.rs

@@ -5,63 +5,68 @@
 use tokio::runtime::{self, Runtime};
 use tokio::sync::oneshot;
 
-use bencher::{benchmark_group, benchmark_main, Bencher};
 use std::sync::atomic::Ordering::Relaxed;
 use std::sync::atomic::{AtomicBool, AtomicUsize};
 use std::sync::{mpsc, Arc};
 use std::time::{Duration, Instant};
 
+use criterion::{criterion_group, criterion_main, Criterion};
+
 const NUM_WORKERS: usize = 4;
 const NUM_SPAWN: usize = 10_000;
 const STALL_DUR: Duration = Duration::from_micros(10);
 
-fn spawn_many_local(b: &mut Bencher) {
+fn rt_multi_spawn_many_local(c: &mut Criterion) {
     let rt = rt();
 
     let (tx, rx) = mpsc::sync_channel(1000);
     let rem = Arc::new(AtomicUsize::new(0));
 
-    b.iter(|| {
-        rem.store(NUM_SPAWN, Relaxed);
+    c.bench_function("spawn_many_local", |b| {
+        b.iter(|| {
+            rem.store(NUM_SPAWN, Relaxed);
 
-        rt.block_on(async {
-            for _ in 0..NUM_SPAWN {
-                let tx = tx.clone();
-                let rem = rem.clone();
+            rt.block_on(async {
+                for _ in 0..NUM_SPAWN {
+                    let tx = tx.clone();
+                    let rem = rem.clone();
 
-                tokio::spawn(async move {
-                    if 1 == rem.fetch_sub(1, Relaxed) {
-                        tx.send(()).unwrap();
-                    }
-                });
-            }
+                    tokio::spawn(async move {
+                        if 1 == rem.fetch_sub(1, Relaxed) {
+                            tx.send(()).unwrap();
+                        }
+                    });
+                }
 
-            let _ = rx.recv().unwrap();
-        });
+                rx.recv().unwrap();
+            });
+        })
     });
 }
 
-fn spawn_many_remote_idle(b: &mut Bencher) {
+fn rt_multi_spawn_many_remote_idle(c: &mut Criterion) {
     let rt = rt();
 
     let mut handles = Vec::with_capacity(NUM_SPAWN);
 
-    b.iter(|| {
-        for _ in 0..NUM_SPAWN {
-            handles.push(rt.spawn(async {}));
-        }
-
-        rt.block_on(async {
-            for handle in handles.drain(..) {
-                handle.await.unwrap();
+    c.bench_function("spawn_many_remote_idle", |b| {
+        b.iter(|| {
+            for _ in 0..NUM_SPAWN {
+                handles.push(rt.spawn(async {}));
             }
-        });
+
+            rt.block_on(async {
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
     });
 }
 
 // The runtime is busy with tasks that consume CPU time and yield. Yielding is a
 // lower notification priority than spawning / regular notification.
-fn spawn_many_remote_busy1(b: &mut Bencher) {
+fn rt_multi_spawn_many_remote_busy1(c: &mut Criterion) {
     let rt = rt();
     let rt_handle = rt.handle();
     let mut handles = Vec::with_capacity(NUM_SPAWN);
@@ -78,16 +83,18 @@ fn spawn_many_remote_busy1(b: &mut Bencher) {
         });
     }
 
-    b.iter(|| {
-        for _ in 0..NUM_SPAWN {
-            handles.push(rt_handle.spawn(async {}));
-        }
-
-        rt.block_on(async {
-            for handle in handles.drain(..) {
-                handle.await.unwrap();
+    c.bench_function("spawn_many_remote_busy1", |b| {
+        b.iter(|| {
+            for _ in 0..NUM_SPAWN {
+                handles.push(rt_handle.spawn(async {}));
             }
-        });
+
+            rt.block_on(async {
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
     });
 
     flag.store(false, Relaxed);
@@ -95,7 +102,7 @@ fn spawn_many_remote_busy1(b: &mut Bencher) {
 
 // The runtime is busy with tasks that consume CPU time and spawn new high-CPU
 // tasks. Spawning goes via a higher notification priority than yielding.
-fn spawn_many_remote_busy2(b: &mut Bencher) {
+fn rt_multi_spawn_many_remote_busy2(c: &mut Criterion) {
     const NUM_SPAWN: usize = 1_000;
 
     let rt = rt();
@@ -119,49 +126,52 @@ fn spawn_many_remote_busy2(b: &mut Bencher) {
         });
     }
 
-    b.iter(|| {
-        for _ in 0..NUM_SPAWN {
-            handles.push(rt_handle.spawn(async {}));
-        }
-
-        rt.block_on(async {
-            for handle in handles.drain(..) {
-                handle.await.unwrap();
+    c.bench_function("spawn_many_remote_busy2", |b| {
+        b.iter(|| {
+            for _ in 0..NUM_SPAWN {
+                handles.push(rt_handle.spawn(async {}));
             }
-        });
+
+            rt.block_on(async {
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
     });
 
     flag.store(false, Relaxed);
 }
 
-fn yield_many(b: &mut Bencher) {
+fn rt_multi_yield_many(c: &mut Criterion) {
     const NUM_YIELD: usize = 1_000;
     const TASKS: usize = 200;
 
-    let rt = rt();
+    c.bench_function("yield_many", |b| {
+        let rt = rt();
+        let (tx, rx) = mpsc::sync_channel(TASKS);
 
-    let (tx, rx) = mpsc::sync_channel(TASKS);
+        b.iter(move || {
+            for _ in 0..TASKS {
+                let tx = tx.clone();
 
-    b.iter(move || {
-        for _ in 0..TASKS {
-            let tx = tx.clone();
+                rt.spawn(async move {
+                    for _ in 0..NUM_YIELD {
+                        tokio::task::yield_now().await;
+                    }
 
-            rt.spawn(async move {
-                for _ in 0..NUM_YIELD {
-                    tokio::task::yield_now().await;
-                }
+                    tx.send(()).unwrap();
+                });
+            }
 
-                tx.send(()).unwrap();
-            });
-        }
-
-        for _ in 0..TASKS {
-            let _ = rx.recv().unwrap();
-        }
+            for _ in 0..TASKS {
+                rx.recv().unwrap();
+            }
+        })
     });
 }
 
-fn ping_pong(b: &mut Bencher) {
+fn rt_multi_ping_pong(c: &mut Criterion) {
     const NUM_PINGS: usize = 1_000;
 
     let rt = rt();
@@ -169,46 +179,46 @@ fn ping_pong(b: &mut Bencher) {
     let (done_tx, done_rx) = mpsc::sync_channel(1000);
     let rem = Arc::new(AtomicUsize::new(0));
 
-    b.iter(|| {
-        let done_tx = done_tx.clone();
-        let rem = rem.clone();
-        rem.store(NUM_PINGS, Relaxed);
+    c.bench_function("ping_pong", |b| {
+        b.iter(|| {
+            let done_tx = done_tx.clone();
+            let rem = rem.clone();
+            rem.store(NUM_PINGS, Relaxed);
 
-        rt.block_on(async {
-            tokio::spawn(async move {
-                for _ in 0..NUM_PINGS {
-                    let rem = rem.clone();
-                    let done_tx = done_tx.clone();
-
-                    tokio::spawn(async move {
-                        let (tx1, rx1) = oneshot::channel();
-                        let (tx2, rx2) = oneshot::channel();
+            rt.block_on(async {
+                tokio::spawn(async move {
+                    for _ in 0..NUM_PINGS {
+                        let rem = rem.clone();
+                        let done_tx = done_tx.clone();
 
                         tokio::spawn(async move {
-                            rx1.await.unwrap();
-                            tx2.send(()).unwrap();
+                            let (tx1, rx1) = oneshot::channel();
+                            let (tx2, rx2) = oneshot::channel();
+
+                            tokio::spawn(async move {
+                                rx1.await.unwrap();
+                                tx2.send(()).unwrap();
+                            });
+
+                            tx1.send(()).unwrap();
+                            rx2.await.unwrap();
+
+                            if 1 == rem.fetch_sub(1, Relaxed) {
+                                done_tx.send(()).unwrap();
+                            }
                         });
+                    }
+                });
 
-                        tx1.send(()).unwrap();
-                        rx2.await.unwrap();
-
-                        if 1 == rem.fetch_sub(1, Relaxed) {
-                            done_tx.send(()).unwrap();
-                        }
-                    });
-                }
+                done_rx.recv().unwrap();
             });
-
-            done_rx.recv().unwrap();
-        });
+        })
     });
 }
 
-fn chained_spawn(b: &mut Bencher) {
+fn rt_multi_chained_spawn(c: &mut Criterion) {
     const ITER: usize = 1_000;
 
-    let rt = rt();
-
     fn iter(done_tx: mpsc::SyncSender<()>, n: usize) {
         if n == 0 {
             done_tx.send(()).unwrap();
@@ -219,18 +229,21 @@ fn chained_spawn(b: &mut Bencher) {
         }
     }
 
-    let (done_tx, done_rx) = mpsc::sync_channel(1000);
+    c.bench_function("chained_spawn", |b| {
+        let rt = rt();
+        let (done_tx, done_rx) = mpsc::sync_channel(1000);
 
-    b.iter(move || {
-        let done_tx = done_tx.clone();
+        b.iter(move || {
+            let done_tx = done_tx.clone();
 
-        rt.block_on(async {
-            tokio::spawn(async move {
-                iter(done_tx, ITER);
+            rt.block_on(async {
+                tokio::spawn(async move {
+                    iter(done_tx, ITER);
+                });
+
+                done_rx.recv().unwrap();
             });
-
-            done_rx.recv().unwrap();
-        });
+        })
     });
 }
 
@@ -249,15 +262,15 @@ fn stall() {
     }
 }
 
-benchmark_group!(
-    scheduler,
-    spawn_many_local,
-    spawn_many_remote_idle,
-    spawn_many_remote_busy1,
-    spawn_many_remote_busy2,
-    ping_pong,
-    yield_many,
-    chained_spawn,
+criterion_group!(
+    rt_multi_scheduler,
+    rt_multi_spawn_many_local,
+    rt_multi_spawn_many_remote_idle,
+    rt_multi_spawn_many_remote_busy1,
+    rt_multi_spawn_many_remote_busy2,
+    rt_multi_ping_pong,
+    rt_multi_yield_many,
+    rt_multi_chained_spawn,
 );
 
-benchmark_main!(scheduler);
+criterion_main!(rt_multi_scheduler);

benches/signal.rs

@@ -1,7 +1,7 @@
 //! Benchmark the delay in propagating OS signals to any listeners.
 #![cfg(unix)]
 
-use bencher::{benchmark_group, benchmark_main, Bencher};
+use criterion::{criterion_group, criterion_main, Criterion};
 use std::future::Future;
 use std::pin::Pin;
 use std::task::{Context, Poll};
@@ -41,7 +41,7 @@ pub fn send_signal(signal: libc::c_int) {
     }
 }
 
-fn many_signals(bench: &mut Bencher) {
+fn many_signals(c: &mut Criterion) {
     let num_signals = 10;
     let (tx, mut rx) = mpsc::channel(num_signals);
 
@@ -75,21 +75,23 @@ fn many_signals(bench: &mut Bencher) {
     // tasks have been polled at least once
     rt.block_on(Spinner::new());
 
-    bench.iter(|| {
-        rt.block_on(async {
-            send_signal(libc::SIGCHLD);
-            for _ in 0..num_signals {
-                rx.recv().await.expect("channel closed");
-            }
+    c.bench_function("many_signals", |b| {
+        b.iter(|| {
+            rt.block_on(async {
+                send_signal(libc::SIGCHLD);
+                for _ in 0..num_signals {
+                    rx.recv().await.expect("channel closed");
+                }
 
-            send_signal(libc::SIGIO);
-            for _ in 0..num_signals {
-                rx.recv().await.expect("channel closed");
-            }
-        });
+                send_signal(libc::SIGIO);
+                for _ in 0..num_signals {
+                    rx.recv().await.expect("channel closed");
+                }
+            });
+        })
     });
 }
 
-benchmark_group!(signal_group, many_signals,);
+criterion_group!(signal_group, many_signals);
 
-benchmark_main!(signal_group);
+criterion_main!(signal_group);

benches/spawn.rs

@@ -2,10 +2,7 @@
 //! This essentially measure the time to enqueue a task in the local and remote
 //! case.
 
-#[macro_use]
-extern crate bencher;
-
-use bencher::{black_box, Bencher};
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
 
 async fn work() -> usize {
     let val = 1 + 1;
@@ -13,67 +10,77 @@ async fn work() -> usize {
     black_box(val)
 }
 
-fn basic_scheduler_spawn(bench: &mut Bencher) {
+fn basic_scheduler_spawn(c: &mut Criterion) {
     let runtime = tokio::runtime::Builder::new_current_thread()
         .build()
         .unwrap();
-    bench.iter(|| {
-        runtime.block_on(async {
-            let h = tokio::spawn(work());
-            assert_eq!(h.await.unwrap(), 2);
-        });
+
+    c.bench_function("basic_scheduler_spawn", |b| {
+        b.iter(|| {
+            runtime.block_on(async {
+                let h = tokio::spawn(work());
+                assert_eq!(h.await.unwrap(), 2);
+            });
+        })
     });
 }
 
-fn basic_scheduler_spawn10(bench: &mut Bencher) {
+fn basic_scheduler_spawn10(c: &mut Criterion) {
     let runtime = tokio::runtime::Builder::new_current_thread()
         .build()
         .unwrap();
-    bench.iter(|| {
-        runtime.block_on(async {
-            let mut handles = Vec::with_capacity(10);
-            for _ in 0..10 {
-                handles.push(tokio::spawn(work()));
-            }
-            for handle in handles {
-                assert_eq!(handle.await.unwrap(), 2);
-            }
-        });
+
+    c.bench_function("basic_scheduler_spawn10", |b| {
+        b.iter(|| {
+            runtime.block_on(async {
+                let mut handles = Vec::with_capacity(10);
+                for _ in 0..10 {
+                    handles.push(tokio::spawn(work()));
+                }
+                for handle in handles {
+                    assert_eq!(handle.await.unwrap(), 2);
+                }
+            });
+        })
     });
 }
 
-fn threaded_scheduler_spawn(bench: &mut Bencher) {
+fn threaded_scheduler_spawn(c: &mut Criterion) {
     let runtime = tokio::runtime::Builder::new_multi_thread()
         .worker_threads(1)
         .build()
         .unwrap();
-    bench.iter(|| {
-        runtime.block_on(async {
-            let h = tokio::spawn(work());
-            assert_eq!(h.await.unwrap(), 2);
-        });
+    c.bench_function("threaded_scheduler_spawn", |b| {
+        b.iter(|| {
+            runtime.block_on(async {
+                let h = tokio::spawn(work());
+                assert_eq!(h.await.unwrap(), 2);
+            });
+        })
     });
 }
 
-fn threaded_scheduler_spawn10(bench: &mut Bencher) {
+fn threaded_scheduler_spawn10(c: &mut Criterion) {
     let runtime = tokio::runtime::Builder::new_multi_thread()
         .worker_threads(1)
         .build()
         .unwrap();
-    bench.iter(|| {
-        runtime.block_on(async {
-            let mut handles = Vec::with_capacity(10);
-            for _ in 0..10 {
-                handles.push(tokio::spawn(work()));
-            }
-            for handle in handles {
-                assert_eq!(handle.await.unwrap(), 2);
-            }
-        });
+    c.bench_function("threaded_scheduler_spawn10", |b| {
+        b.iter(|| {
+            runtime.block_on(async {
+                let mut handles = Vec::with_capacity(10);
+                for _ in 0..10 {
+                    handles.push(tokio::spawn(work()));
+                }
+                for handle in handles {
+                    assert_eq!(handle.await.unwrap(), 2);
+                }
+            });
+        })
     });
 }
 
-bencher::benchmark_group!(
+criterion_group!(
     spawn,
     basic_scheduler_spawn,
     basic_scheduler_spawn10,
@@ -81,4 +88,4 @@ bencher::benchmark_group!(
     threaded_scheduler_spawn10,
 );
 
-bencher::benchmark_main!(spawn);
+criterion_main!(spawn);

benches/sync_broadcast.rs

@@ -0,0 +1,82 @@
+use rand::{Rng, RngCore, SeedableRng};
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+use tokio::sync::{broadcast, Notify};
+
+use criterion::measurement::WallTime;
+use criterion::{black_box, criterion_group, criterion_main, BenchmarkGroup, Criterion};
+
+fn rt() -> tokio::runtime::Runtime {
+    tokio::runtime::Builder::new_multi_thread()
+        .worker_threads(6)
+        .build()
+        .unwrap()
+}
+
+fn do_work(rng: &mut impl RngCore) -> u32 {
+    use std::fmt::Write;
+    let mut message = String::new();
+    for i in 1..=10 {
+        let _ = write!(&mut message, " {i}={}", rng.gen::<f64>());
+    }
+    message
+        .as_bytes()
+        .iter()
+        .map(|&c| c as u32)
+        .fold(0, u32::wrapping_add)
+}
+
+fn contention_impl<const N_TASKS: usize>(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
+
+    let (tx, _rx) = broadcast::channel::<usize>(1000);
+    let wg = Arc::new((AtomicUsize::new(0), Notify::new()));
+
+    for n in 0..N_TASKS {
+        let wg = wg.clone();
+        let mut rx = tx.subscribe();
+        let mut rng = rand::rngs::StdRng::seed_from_u64(n as u64);
+        rt.spawn(async move {
+            while (rx.recv().await).is_ok() {
+                let r = do_work(&mut rng);
+                let _ = black_box(r);
+                if wg.0.fetch_sub(1, Ordering::Relaxed) == 1 {
+                    wg.1.notify_one();
+                }
+            }
+        });
+    }
+
+    const N_ITERS: usize = 100;
+
+    g.bench_function(N_TASKS.to_string(), |b| {
+        b.iter(|| {
+            rt.block_on({
+                let wg = wg.clone();
+                let tx = tx.clone();
+                async move {
+                    for i in 0..N_ITERS {
+                        assert_eq!(wg.0.fetch_add(N_TASKS, Ordering::Relaxed), 0);
+                        tx.send(i).unwrap();
+                        while wg.0.load(Ordering::Relaxed) > 0 {
+                            wg.1.notified().await;
+                        }
+                    }
+                }
+            })
+        })
+    });
+}
+
+fn bench_contention(c: &mut Criterion) {
+    let mut group = c.benchmark_group("contention");
+    contention_impl::<10>(&mut group);
+    contention_impl::<100>(&mut group);
+    contention_impl::<500>(&mut group);
+    contention_impl::<1000>(&mut group);
+    group.finish();
+}
+
+criterion_group!(contention, bench_contention);
+
+criterion_main!(contention);

benches/sync_mpsc.rs

@@ -1,8 +1,23 @@
-use bencher::{black_box, Bencher};
 use tokio::sync::mpsc;
 
-type Medium = [usize; 64];
-type Large = [Medium; 64];
+use criterion::measurement::WallTime;
+use criterion::{black_box, criterion_group, criterion_main, BenchmarkGroup, Criterion};
+
+#[derive(Debug, Copy, Clone)]
+struct Medium(#[allow(dead_code)] [usize; 64]);
+impl Default for Medium {
+    fn default() -> Self {
+        Medium([0; 64])
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+struct Large(#[allow(dead_code)] [Medium; 64]);
+impl Default for Large {
+    fn default() -> Self {
+        Large([Medium::default(); 64])
+    }
+}
 
 fn rt() -> tokio::runtime::Runtime {
     tokio::runtime::Builder::new_multi_thread()
@@ -11,169 +26,306 @@ fn rt() -> tokio::runtime::Runtime {
         .unwrap()
 }
 
-fn create_1_medium(b: &mut Bencher) {
-    b.iter(|| {
-        black_box(&mpsc::channel::<Medium>(1));
-    });
-}
-
-fn create_100_medium(b: &mut Bencher) {
-    b.iter(|| {
-        black_box(&mpsc::channel::<Medium>(100));
-    });
-}
-
-fn create_100_000_medium(b: &mut Bencher) {
-    b.iter(|| {
-        black_box(&mpsc::channel::<Medium>(100_000));
-    });
-}
-
-fn send_medium(b: &mut Bencher) {
-    let rt = rt();
-
-    b.iter(|| {
-        let (tx, mut rx) = mpsc::channel::<Medium>(1000);
-
-        let _ = rt.block_on(tx.send([0; 64]));
-
-        rt.block_on(rx.recv()).unwrap();
-    });
-}
-
-fn send_large(b: &mut Bencher) {
-    let rt = rt();
-
-    b.iter(|| {
-        let (tx, mut rx) = mpsc::channel::<Large>(1000);
-
-        let _ = rt.block_on(tx.send([[0; 64]; 64]));
-
-        rt.block_on(rx.recv()).unwrap();
-    });
-}
-
-fn contention_bounded(b: &mut Bencher) {
-    let rt = rt();
-
-    b.iter(|| {
-        rt.block_on(async move {
-            let (tx, mut rx) = mpsc::channel::<usize>(1_000_000);
-
-            for _ in 0..5 {
-                let tx = tx.clone();
-                tokio::spawn(async move {
-                    for i in 0..1000 {
-                        tx.send(i).await.unwrap();
-                    }
-                });
-            }
-
-            for _ in 0..1_000 * 5 {
-                let _ = rx.recv().await;
-            }
+fn create_medium<const SIZE: usize>(g: &mut BenchmarkGroup<WallTime>) {
+    g.bench_function(SIZE.to_string(), |b| {
+        b.iter(|| {
+            black_box(&mpsc::channel::<Medium>(SIZE));
         })
     });
 }
 
-fn contention_bounded_full(b: &mut Bencher) {
+fn send_data<T: Default, const SIZE: usize>(g: &mut BenchmarkGroup<WallTime>, prefix: &str) {
     let rt = rt();
 
-    b.iter(|| {
-        rt.block_on(async move {
-            let (tx, mut rx) = mpsc::channel::<usize>(100);
+    g.bench_function(format!("{}_{}", prefix, SIZE), |b| {
+        b.iter(|| {
+            let (tx, mut rx) = mpsc::channel::<T>(SIZE);
 
-            for _ in 0..5 {
-                let tx = tx.clone();
-                tokio::spawn(async move {
-                    for i in 0..1000 {
-                        tx.send(i).await.unwrap();
-                    }
-                });
-            }
+            let _ = rt.block_on(tx.send(T::default()));
 
-            for _ in 0..1_000 * 5 {
-                let _ = rx.recv().await;
-            }
+            rt.block_on(rx.recv()).unwrap();
         })
     });
 }
 
-fn contention_unbounded(b: &mut Bencher) {
+fn contention_bounded(g: &mut BenchmarkGroup<WallTime>) {
     let rt = rt();
 
-    b.iter(|| {
-        rt.block_on(async move {
-            let (tx, mut rx) = mpsc::unbounded_channel::<usize>();
+    g.bench_function("bounded", |b| {
+        b.iter(|| {
+            rt.block_on(async move {
+                let (tx, mut rx) = mpsc::channel::<usize>(1_000_000);
 
-            for _ in 0..5 {
-                let tx = tx.clone();
-                tokio::spawn(async move {
-                    for i in 0..1000 {
-                        tx.send(i).unwrap();
-                    }
-                });
-            }
+                for _ in 0..5 {
+                    let tx = tx.clone();
+                    tokio::spawn(async move {
+                        for i in 0..1000 {
+                            tx.send(i).await.unwrap();
+                        }
+                    });
+                }
 
-            for _ in 0..1_000 * 5 {
-                let _ = rx.recv().await;
-            }
+                for _ in 0..1_000 * 5 {
+                    let _ = rx.recv().await;
+                }
+            })
         })
     });
 }
 
-fn uncontented_bounded(b: &mut Bencher) {
+fn contention_bounded_recv_many(g: &mut BenchmarkGroup<WallTime>) {
     let rt = rt();
 
-    b.iter(|| {
-        rt.block_on(async move {
-            let (tx, mut rx) = mpsc::channel::<usize>(1_000_000);
+    g.bench_function("bounded_recv_many", |b| {
+        b.iter(|| {
+            rt.block_on(async move {
+                let (tx, mut rx) = mpsc::channel::<usize>(1_000_000);
 
-            for i in 0..5000 {
-                tx.send(i).await.unwrap();
-            }
+                for _ in 0..5 {
+                    let tx = tx.clone();
+                    tokio::spawn(async move {
+                        for i in 0..1000 {
+                            tx.send(i).await.unwrap();
+                        }
+                    });
+                }
 
-            for _ in 0..5_000 {
-                let _ = rx.recv().await;
-            }
+                let mut buffer = Vec::<usize>::with_capacity(5_000);
+                let mut total = 0;
+                while total < 1_000 * 5 {
+                    total += rx.recv_many(&mut buffer, 5_000).await;
+                }
+            })
         })
     });
 }
 
-fn uncontented_unbounded(b: &mut Bencher) {
+fn contention_bounded_full(g: &mut BenchmarkGroup<WallTime>) {
     let rt = rt();
 
-    b.iter(|| {
-        rt.block_on(async move {
-            let (tx, mut rx) = mpsc::unbounded_channel::<usize>();
+    g.bench_function("bounded_full", |b| {
+        b.iter(|| {
+            rt.block_on(async move {
+                let (tx, mut rx) = mpsc::channel::<usize>(100);
 
-            for i in 0..5000 {
-                tx.send(i).unwrap();
-            }
+                for _ in 0..5 {
+                    let tx = tx.clone();
+                    tokio::spawn(async move {
+                        for i in 0..1000 {
+                            tx.send(i).await.unwrap();
+                        }
+                    });
+                }
 
-            for _ in 0..5_000 {
-                let _ = rx.recv().await;
-            }
+                for _ in 0..1_000 * 5 {
+                    let _ = rx.recv().await;
+                }
+            })
         })
     });
 }
 
-bencher::benchmark_group!(
-    create,
-    create_1_medium,
-    create_100_medium,
-    create_100_000_medium
-);
+fn contention_bounded_full_recv_many(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
 
-bencher::benchmark_group!(send, send_medium, send_large);
+    g.bench_function("bounded_full_recv_many", |b| {
+        b.iter(|| {
+            rt.block_on(async move {
+                let (tx, mut rx) = mpsc::channel::<usize>(100);
 
-bencher::benchmark_group!(
-    contention,
-    contention_bounded,
-    contention_bounded_full,
-    contention_unbounded,
-    uncontented_bounded,
-    uncontented_unbounded
-);
+                for _ in 0..5 {
+                    let tx = tx.clone();
+                    tokio::spawn(async move {
+                        for i in 0..1000 {
+                            tx.send(i).await.unwrap();
+                        }
+                    });
+                }
 
-bencher::benchmark_main!(create, send, contention);
+                let mut buffer = Vec::<usize>::with_capacity(5_000);
+                let mut total = 0;
+                while total < 1_000 * 5 {
+                    total += rx.recv_many(&mut buffer, 5_000).await;
+                }
+            })
+        })
+    });
+}
+
+fn contention_unbounded(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
+
+    g.bench_function("unbounded", |b| {
+        b.iter(|| {
+            rt.block_on(async move {
+                let (tx, mut rx) = mpsc::unbounded_channel::<usize>();
+
+                for _ in 0..5 {
+                    let tx = tx.clone();
+                    tokio::spawn(async move {
+                        for i in 0..1000 {
+                            tx.send(i).unwrap();
+                        }
+                    });
+                }
+
+                for _ in 0..1_000 * 5 {
+                    let _ = rx.recv().await;
+                }
+            })
+        })
+    });
+}
+
+fn contention_unbounded_recv_many(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
+
+    g.bench_function("unbounded_recv_many", |b| {
+        b.iter(|| {
+            rt.block_on(async move {
+                let (tx, mut rx) = mpsc::unbounded_channel::<usize>();
+
+                for _ in 0..5 {
+                    let tx = tx.clone();
+                    tokio::spawn(async move {
+                        for i in 0..1000 {
+                            tx.send(i).unwrap();
+                        }
+                    });
+                }
+
+                let mut buffer = Vec::<usize>::with_capacity(5_000);
+                let mut total = 0;
+                while total < 1_000 * 5 {
+                    total += rx.recv_many(&mut buffer, 5_000).await;
+                }
+            })
+        })
+    });
+}
+
+fn uncontented_bounded(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
+
+    g.bench_function("bounded", |b| {
+        b.iter(|| {
+            rt.block_on(async move {
+                let (tx, mut rx) = mpsc::channel::<usize>(1_000_000);
+
+                for i in 0..5000 {
+                    tx.send(i).await.unwrap();
+                }
+
+                for _ in 0..5_000 {
+                    let _ = rx.recv().await;
+                }
+            })
+        })
+    });
+}
+
+fn uncontented_bounded_recv_many(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
+
+    g.bench_function("bounded_recv_many", |b| {
+        b.iter(|| {
+            rt.block_on(async move {
+                let (tx, mut rx) = mpsc::channel::<usize>(1_000_000);
+
+                for i in 0..5000 {
+                    tx.send(i).await.unwrap();
+                }
+
+                let mut buffer = Vec::<usize>::with_capacity(5_000);
+                let mut total = 0;
+                while total < 1_000 * 5 {
+                    total += rx.recv_many(&mut buffer, 5_000).await;
+                }
+            })
+        })
+    });
+}
+
+fn uncontented_unbounded(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
+
+    g.bench_function("unbounded", |b| {
+        b.iter(|| {
+            rt.block_on(async move {
+                let (tx, mut rx) = mpsc::unbounded_channel::<usize>();
+
+                for i in 0..5000 {
+                    tx.send(i).unwrap();
+                }
+
+                for _ in 0..5_000 {
+                    let _ = rx.recv().await;
+                }
+            })
+        })
+    });
+}
+
+fn uncontented_unbounded_recv_many(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
+
+    g.bench_function("unbounded_recv_many", |b| {
+        b.iter(|| {
+            rt.block_on(async move {
+                let (tx, mut rx) = mpsc::unbounded_channel::<usize>();
+
+                for i in 0..5000 {
+                    tx.send(i).unwrap();
+                }
+
+                let mut buffer = Vec::<usize>::with_capacity(5_000);
+                let mut total = 0;
+                while total < 1_000 * 5 {
+                    total += rx.recv_many(&mut buffer, 5_000).await;
+                }
+            })
+        })
+    });
+}
+
+fn bench_create_medium(c: &mut Criterion) {
+    let mut group = c.benchmark_group("create_medium");
+    create_medium::<1>(&mut group);
+    create_medium::<100>(&mut group);
+    create_medium::<100_000>(&mut group);
+    group.finish();
+}
+
+fn bench_send(c: &mut Criterion) {
+    let mut group = c.benchmark_group("send");
+    send_data::<Medium, 1000>(&mut group, "medium");
+    send_data::<Large, 1000>(&mut group, "large");
+    group.finish();
+}
+
+fn bench_contention(c: &mut Criterion) {
+    let mut group = c.benchmark_group("contention");
+    contention_bounded(&mut group);
+    contention_bounded_recv_many(&mut group);
+    contention_bounded_full(&mut group);
+    contention_bounded_full_recv_many(&mut group);
+    contention_unbounded(&mut group);
+    contention_unbounded_recv_many(&mut group);
+    group.finish();
+}
+
+fn bench_uncontented(c: &mut Criterion) {
+    let mut group = c.benchmark_group("uncontented");
+    uncontented_bounded(&mut group);
+    uncontented_bounded_recv_many(&mut group);
+    uncontented_unbounded(&mut group);
+    uncontented_unbounded_recv_many(&mut group);
+    group.finish();
+}
+
+criterion_group!(create, bench_create_medium);
+criterion_group!(send, bench_send);
+criterion_group!(contention, bench_contention);
+criterion_group!(uncontented, bench_uncontented);
+
+criterion_main!(create, send, contention, uncontented);

benches/sync_mpsc_oneshot.rs

@@ -1,27 +1,28 @@
-use bencher::{benchmark_group, benchmark_main, Bencher};
 use tokio::{
     runtime::Runtime,
     sync::{mpsc, oneshot},
 };
 
-fn request_reply_current_thread(b: &mut Bencher) {
+use criterion::{criterion_group, criterion_main, Criterion};
+
+fn request_reply_current_thread(c: &mut Criterion) {
     let rt = tokio::runtime::Builder::new_current_thread()
         .build()
         .unwrap();
 
-    request_reply(b, rt);
+    request_reply(c, rt);
 }
 
-fn request_reply_multi_threaded(b: &mut Bencher) {
+fn request_reply_multi_threaded(c: &mut Criterion) {
     let rt = tokio::runtime::Builder::new_multi_thread()
         .worker_threads(1)
         .build()
         .unwrap();
 
-    request_reply(b, rt);
+    request_reply(c, rt);
 }
 
-fn request_reply(b: &mut Bencher, rt: Runtime) {
+fn request_reply(b: &mut Criterion, rt: Runtime) {
     let tx = rt.block_on(async move {
         let (tx, mut rx) = mpsc::channel::<oneshot::Sender<()>>(10);
         tokio::spawn(async move {
@@ -32,22 +33,24 @@ fn request_reply(b: &mut Bencher, rt: Runtime) {
         tx
     });
 
-    b.iter(|| {
-        let task_tx = tx.clone();
-        rt.block_on(async move {
-            for _ in 0..1_000 {
-                let (o_tx, o_rx) = oneshot::channel();
-                task_tx.send(o_tx).await.unwrap();
-                let _ = o_rx.await;
-            }
+    b.bench_function("request_reply", |b| {
+        b.iter(|| {
+            let task_tx = tx.clone();
+            rt.block_on(async move {
+                for _ in 0..1_000 {
+                    let (o_tx, o_rx) = oneshot::channel();
+                    task_tx.send(o_tx).await.unwrap();
+                    let _ = o_rx.await;
+                }
+            })
         })
     });
 }
 
-benchmark_group!(
+criterion_group!(
     sync_mpsc_oneshot_group,
     request_reply_current_thread,
     request_reply_multi_threaded,
 );
 
-benchmark_main!(sync_mpsc_oneshot_group);
+criterion_main!(sync_mpsc_oneshot_group);

benches/sync_notify.rs

@@ -1,9 +1,11 @@
-use bencher::Bencher;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Arc;
 
 use tokio::sync::Notify;
 
+use criterion::measurement::WallTime;
+use criterion::{criterion_group, criterion_main, BenchmarkGroup, Criterion};
+
 fn rt() -> tokio::runtime::Runtime {
     tokio::runtime::Builder::new_multi_thread()
         .worker_threads(6)
@@ -11,7 +13,7 @@ fn rt() -> tokio::runtime::Runtime {
         .unwrap()
 }
 
-fn notify_waiters<const N_WAITERS: usize>(b: &mut Bencher) {
+fn notify_waiters<const N_WAITERS: usize>(g: &mut BenchmarkGroup<WallTime>) {
     let rt = rt();
     let notify = Arc::new(Notify::new());
     let counter = Arc::new(AtomicUsize::new(0));
@@ -29,18 +31,20 @@ fn notify_waiters<const N_WAITERS: usize>(b: &mut Bencher) {
     }
 
     const N_ITERS: usize = 500;
-    b.iter(|| {
-        counter.store(0, Ordering::Relaxed);
-        loop {
-            notify.notify_waiters();
-            if counter.load(Ordering::Relaxed) >= N_ITERS {
-                break;
+    g.bench_function(N_WAITERS.to_string(), |b| {
+        b.iter(|| {
+            counter.store(0, Ordering::Relaxed);
+            loop {
+                notify.notify_waiters();
+                if counter.load(Ordering::Relaxed) >= N_ITERS {
+                    break;
+                }
             }
-        }
+        })
     });
 }
 
-fn notify_one<const N_WAITERS: usize>(b: &mut Bencher) {
+fn notify_one<const N_WAITERS: usize>(g: &mut BenchmarkGroup<WallTime>) {
     let rt = rt();
     let notify = Arc::new(Notify::new());
     let counter = Arc::new(AtomicUsize::new(0));
@@ -58,33 +62,43 @@ fn notify_one<const N_WAITERS: usize>(b: &mut Bencher) {
     }
 
     const N_ITERS: usize = 500;
-    b.iter(|| {
-        counter.store(0, Ordering::Relaxed);
-        loop {
-            notify.notify_one();
-            if counter.load(Ordering::Relaxed) >= N_ITERS {
-                break;
+    g.bench_function(N_WAITERS.to_string(), |b| {
+        b.iter(|| {
+            counter.store(0, Ordering::Relaxed);
+            loop {
+                notify.notify_one();
+                if counter.load(Ordering::Relaxed) >= N_ITERS {
+                    break;
+                }
             }
-        }
+        })
     });
 }
 
-bencher::benchmark_group!(
+fn bench_notify_one(c: &mut Criterion) {
+    let mut group = c.benchmark_group("notify_one");
+    notify_one::<10>(&mut group);
+    notify_one::<50>(&mut group);
+    notify_one::<100>(&mut group);
+    notify_one::<200>(&mut group);
+    notify_one::<500>(&mut group);
+    group.finish();
+}
+
+fn bench_notify_waiters(c: &mut Criterion) {
+    let mut group = c.benchmark_group("notify_waiters");
+    notify_waiters::<10>(&mut group);
+    notify_waiters::<50>(&mut group);
+    notify_waiters::<100>(&mut group);
+    notify_waiters::<200>(&mut group);
+    notify_waiters::<500>(&mut group);
+    group.finish();
+}
+
+criterion_group!(
     notify_waiters_simple,
-    notify_waiters::<10>,
-    notify_waiters::<50>,
-    notify_waiters::<100>,
-    notify_waiters::<200>,
-    notify_waiters::<500>
+    bench_notify_one,
+    bench_notify_waiters
 );
 
-bencher::benchmark_group!(
-    notify_one_simple,
-    notify_one::<10>,
-    notify_one::<50>,
-    notify_one::<100>,
-    notify_one::<200>,
-    notify_one::<500>
-);
-
-bencher::benchmark_main!(notify_waiters_simple, notify_one_simple);
+criterion_main!(notify_waiters_simple);

benches/sync_rwlock.rs

@@ -1,26 +1,30 @@
-use bencher::{black_box, Bencher};
 use std::sync::Arc;
 use tokio::{sync::RwLock, task};
 
-fn read_uncontended(b: &mut Bencher) {
+use criterion::measurement::WallTime;
+use criterion::{black_box, criterion_group, criterion_main, BenchmarkGroup, Criterion};
+
+fn read_uncontended(g: &mut BenchmarkGroup<WallTime>) {
     let rt = tokio::runtime::Builder::new_multi_thread()
         .worker_threads(6)
         .build()
         .unwrap();
 
     let lock = Arc::new(RwLock::new(()));
-    b.iter(|| {
-        let lock = lock.clone();
-        rt.block_on(async move {
-            for _ in 0..6 {
-                let read = lock.read().await;
-                let _read = black_box(read);
-            }
+    g.bench_function("read", |b| {
+        b.iter(|| {
+            let lock = lock.clone();
+            rt.block_on(async move {
+                for _ in 0..6 {
+                    let read = lock.read().await;
+                    let _read = black_box(read);
+                }
+            })
         })
     });
 }
 
-fn read_concurrent_uncontended_multi(b: &mut Bencher) {
+fn read_concurrent_uncontended_multi(g: &mut BenchmarkGroup<WallTime>) {
     let rt = tokio::runtime::Builder::new_multi_thread()
         .worker_threads(6)
         .build()
@@ -32,23 +36,25 @@ fn read_concurrent_uncontended_multi(b: &mut Bencher) {
     }
 
     let lock = Arc::new(RwLock::new(()));
-    b.iter(|| {
-        let lock = lock.clone();
-        rt.block_on(async move {
-            let j = tokio::try_join! {
-                task::spawn(task(lock.clone())),
-                task::spawn(task(lock.clone())),
-                task::spawn(task(lock.clone())),
-                task::spawn(task(lock.clone())),
-                task::spawn(task(lock.clone())),
-                task::spawn(task(lock.clone()))
-            };
-            j.unwrap();
+    g.bench_function("read_concurrent_multi", |b| {
+        b.iter(|| {
+            let lock = lock.clone();
+            rt.block_on(async move {
+                let j = tokio::try_join! {
+                    task::spawn(task(lock.clone())),
+                    task::spawn(task(lock.clone())),
+                    task::spawn(task(lock.clone())),
+                    task::spawn(task(lock.clone())),
+                    task::spawn(task(lock.clone())),
+                    task::spawn(task(lock.clone()))
+                };
+                j.unwrap();
+            })
         })
     });
 }
 
-fn read_concurrent_uncontended(b: &mut Bencher) {
+fn read_concurrent_uncontended(g: &mut BenchmarkGroup<WallTime>) {
     let rt = tokio::runtime::Builder::new_current_thread()
         .build()
         .unwrap();
@@ -59,22 +65,24 @@ fn read_concurrent_uncontended(b: &mut Bencher) {
     }
 
     let lock = Arc::new(RwLock::new(()));
-    b.iter(|| {
-        let lock = lock.clone();
-        rt.block_on(async move {
-            tokio::join! {
-                task(lock.clone()),
-                task(lock.clone()),
-                task(lock.clone()),
-                task(lock.clone()),
-                task(lock.clone()),
-                task(lock.clone())
-            };
+    g.bench_function("read_concurrent", |b| {
+        b.iter(|| {
+            let lock = lock.clone();
+            rt.block_on(async move {
+                tokio::join! {
+                    task(lock.clone()),
+                    task(lock.clone()),
+                    task(lock.clone()),
+                    task(lock.clone()),
+                    task(lock.clone()),
+                    task(lock.clone())
+                };
+            })
         })
     });
 }
 
-fn read_concurrent_contended_multi(b: &mut Bencher) {
+fn read_concurrent_contended_multi(g: &mut BenchmarkGroup<WallTime>) {
     let rt = tokio::runtime::Builder::new_multi_thread()
         .worker_threads(6)
         .build()
@@ -86,24 +94,26 @@ fn read_concurrent_contended_multi(b: &mut Bencher) {
     }
 
     let lock = Arc::new(RwLock::new(()));
-    b.iter(|| {
-        let lock = lock.clone();
-        rt.block_on(async move {
-            let write = lock.write().await;
-            let j = tokio::try_join! {
-                async move { drop(write); Ok(()) },
-                task::spawn(task(lock.clone())),
-                task::spawn(task(lock.clone())),
-                task::spawn(task(lock.clone())),
-                task::spawn(task(lock.clone())),
-                task::spawn(task(lock.clone())),
-            };
-            j.unwrap();
+    g.bench_function("read_concurrent_multi", |b| {
+        b.iter(|| {
+            let lock = lock.clone();
+            rt.block_on(async move {
+                let write = lock.write().await;
+                let j = tokio::try_join! {
+                    async move { drop(write); Ok(()) },
+                    task::spawn(task(lock.clone())),
+                    task::spawn(task(lock.clone())),
+                    task::spawn(task(lock.clone())),
+                    task::spawn(task(lock.clone())),
+                    task::spawn(task(lock.clone())),
+                };
+                j.unwrap();
+            })
         })
     });
 }
 
-fn read_concurrent_contended(b: &mut Bencher) {
+fn read_concurrent_contended(g: &mut BenchmarkGroup<WallTime>) {
     let rt = tokio::runtime::Builder::new_current_thread()
         .build()
         .unwrap();
@@ -114,29 +124,40 @@ fn read_concurrent_contended(b: &mut Bencher) {
     }
 
     let lock = Arc::new(RwLock::new(()));
-    b.iter(|| {
-        let lock = lock.clone();
-        rt.block_on(async move {
-            let write = lock.write().await;
-            tokio::join! {
-                async move { drop(write) },
-                task(lock.clone()),
-                task(lock.clone()),
-                task(lock.clone()),
-                task(lock.clone()),
-                task(lock.clone()),
-            };
+    g.bench_function("read_concurrent", |b| {
+        b.iter(|| {
+            let lock = lock.clone();
+            rt.block_on(async move {
+                let write = lock.write().await;
+                tokio::join! {
+                    async move { drop(write) },
+                    task(lock.clone()),
+                    task(lock.clone()),
+                    task(lock.clone()),
+                    task(lock.clone()),
+                    task(lock.clone()),
+                };
+            })
         })
     });
 }
 
-bencher::benchmark_group!(
-    sync_rwlock,
-    read_uncontended,
-    read_concurrent_uncontended,
-    read_concurrent_uncontended_multi,
-    read_concurrent_contended,
-    read_concurrent_contended_multi
-);
+fn bench_contention(c: &mut Criterion) {
+    let mut group = c.benchmark_group("contention");
+    read_concurrent_contended(&mut group);
+    read_concurrent_contended_multi(&mut group);
+    group.finish();
+}
 
-bencher::benchmark_main!(sync_rwlock);
+fn bench_uncontented(c: &mut Criterion) {
+    let mut group = c.benchmark_group("uncontented");
+    read_uncontended(&mut group);
+    read_concurrent_uncontended(&mut group);
+    read_concurrent_uncontended_multi(&mut group);
+    group.finish();
+}
+
+criterion_group!(contention, bench_contention);
+criterion_group!(uncontented, bench_uncontented);
+
+criterion_main!(contention, uncontented);

benches/sync_semaphore.rs

@@ -1,21 +1,36 @@
-use bencher::Bencher;
 use std::sync::Arc;
+use tokio::runtime::Runtime;
 use tokio::{sync::Semaphore, task};
 
-fn uncontended(b: &mut Bencher) {
-    let rt = tokio::runtime::Builder::new_multi_thread()
+use criterion::measurement::WallTime;
+use criterion::{criterion_group, criterion_main, BenchmarkGroup, Criterion};
+
+fn single_rt() -> Runtime {
+    tokio::runtime::Builder::new_current_thread()
+        .build()
+        .unwrap()
+}
+
+fn multi_rt() -> Runtime {
+    tokio::runtime::Builder::new_multi_thread()
         .worker_threads(6)
         .build()
-        .unwrap();
+        .unwrap()
+}
+
+fn uncontended(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = multi_rt();
 
     let s = Arc::new(Semaphore::new(10));
-    b.iter(|| {
-        let s = s.clone();
-        rt.block_on(async move {
-            for _ in 0..6 {
-                let permit = s.acquire().await;
-                drop(permit);
-            }
+    g.bench_function("multi", |b| {
+        b.iter(|| {
+            let s = s.clone();
+            rt.block_on(async move {
+                for _ in 0..6 {
+                    let permit = s.acquire().await;
+                    drop(permit);
+                }
+            })
         })
     });
 }
@@ -25,101 +40,108 @@ async fn task(s: Arc<Semaphore>) {
     drop(permit);
 }
 
-fn uncontended_concurrent_multi(b: &mut Bencher) {
-    let rt = tokio::runtime::Builder::new_multi_thread()
-        .worker_threads(6)
-        .build()
-        .unwrap();
+fn uncontended_concurrent_multi(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = multi_rt();
 
     let s = Arc::new(Semaphore::new(10));
-    b.iter(|| {
-        let s = s.clone();
-        rt.block_on(async move {
-            let j = tokio::try_join! {
-                task::spawn(task(s.clone())),
-                task::spawn(task(s.clone())),
-                task::spawn(task(s.clone())),
-                task::spawn(task(s.clone())),
-                task::spawn(task(s.clone())),
-                task::spawn(task(s.clone()))
-            };
-            j.unwrap();
+    g.bench_function("concurrent_multi", |b| {
+        b.iter(|| {
+            let s = s.clone();
+            rt.block_on(async move {
+                let j = tokio::try_join! {
+                    task::spawn(task(s.clone())),
+                    task::spawn(task(s.clone())),
+                    task::spawn(task(s.clone())),
+                    task::spawn(task(s.clone())),
+                    task::spawn(task(s.clone())),
+                    task::spawn(task(s.clone()))
+                };
+                j.unwrap();
+            })
         })
     });
 }
 
-fn uncontended_concurrent_single(b: &mut Bencher) {
-    let rt = tokio::runtime::Builder::new_current_thread()
-        .build()
-        .unwrap();
+fn uncontended_concurrent_single(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = single_rt();
 
     let s = Arc::new(Semaphore::new(10));
-    b.iter(|| {
-        let s = s.clone();
-        rt.block_on(async move {
-            tokio::join! {
-                task(s.clone()),
-                task(s.clone()),
-                task(s.clone()),
-                task(s.clone()),
-                task(s.clone()),
-                task(s.clone())
-            };
+    g.bench_function("concurrent_single", |b| {
+        b.iter(|| {
+            let s = s.clone();
+            rt.block_on(async move {
+                tokio::join! {
+                    task(s.clone()),
+                    task(s.clone()),
+                    task(s.clone()),
+                    task(s.clone()),
+                    task(s.clone()),
+                    task(s.clone())
+                };
+            })
         })
     });
 }
 
-fn contended_concurrent_multi(b: &mut Bencher) {
-    let rt = tokio::runtime::Builder::new_multi_thread()
-        .worker_threads(6)
-        .build()
-        .unwrap();
+fn contended_concurrent_multi(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = multi_rt();
 
     let s = Arc::new(Semaphore::new(5));
-    b.iter(|| {
-        let s = s.clone();
-        rt.block_on(async move {
-            let j = tokio::try_join! {
-                task::spawn(task(s.clone())),
-                task::spawn(task(s.clone())),
-                task::spawn(task(s.clone())),
-                task::spawn(task(s.clone())),
-                task::spawn(task(s.clone())),
-                task::spawn(task(s.clone()))
-            };
-            j.unwrap();
+    g.bench_function("concurrent_multi", |b| {
+        b.iter(|| {
+            let s = s.clone();
+            rt.block_on(async move {
+                let j = tokio::try_join! {
+                    task::spawn(task(s.clone())),
+                    task::spawn(task(s.clone())),
+                    task::spawn(task(s.clone())),
+                    task::spawn(task(s.clone())),
+                    task::spawn(task(s.clone())),
+                    task::spawn(task(s.clone()))
+                };
+                j.unwrap();
+            })
         })
     });
 }
 
-fn contended_concurrent_single(b: &mut Bencher) {
-    let rt = tokio::runtime::Builder::new_current_thread()
-        .build()
-        .unwrap();
+fn contended_concurrent_single(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = single_rt();
 
     let s = Arc::new(Semaphore::new(5));
-    b.iter(|| {
-        let s = s.clone();
-        rt.block_on(async move {
-            tokio::join! {
-                task(s.clone()),
-                task(s.clone()),
-                task(s.clone()),
-                task(s.clone()),
-                task(s.clone()),
-                task(s.clone())
-            };
+    g.bench_function("concurrent_single", |b| {
+        b.iter(|| {
+            let s = s.clone();
+            rt.block_on(async move {
+                tokio::join! {
+                    task(s.clone()),
+                    task(s.clone()),
+                    task(s.clone()),
+                    task(s.clone()),
+                    task(s.clone()),
+                    task(s.clone())
+                };
+            })
         })
     });
 }
 
-bencher::benchmark_group!(
-    sync_semaphore,
-    uncontended,
-    uncontended_concurrent_multi,
-    uncontended_concurrent_single,
-    contended_concurrent_multi,
-    contended_concurrent_single
-);
+fn bench_contention(c: &mut Criterion) {
+    let mut group = c.benchmark_group("contention");
+    contended_concurrent_multi(&mut group);
+    contended_concurrent_single(&mut group);
+    group.finish();
+}
 
-bencher::benchmark_main!(sync_semaphore);
+fn bench_uncontented(c: &mut Criterion) {
+    let mut group = c.benchmark_group("uncontented");
+    uncontended(&mut group);
+    uncontended_concurrent_multi(&mut group);
+    uncontended_concurrent_single(&mut group);
+    group.finish();
+}
+
+criterion_group!(contention, bench_contention);
+criterion_group!(uncontented, bench_uncontented);
+
+criterion_main!(contention, uncontented);

benches/sync_watch.rs

@@ -1,9 +1,11 @@
-use bencher::{black_box, Bencher};
 use rand::prelude::*;
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::Arc;
 use tokio::sync::{watch, Notify};
 
+use criterion::measurement::WallTime;
+use criterion::{black_box, criterion_group, criterion_main, BenchmarkGroup, Criterion};
+
 fn rt() -> tokio::runtime::Runtime {
     tokio::runtime::Builder::new_multi_thread()
         .worker_threads(6)
@@ -24,16 +26,15 @@ fn do_work(rng: &mut impl RngCore) -> u32 {
         .fold(0, u32::wrapping_add)
 }
 
-fn contention_resubscribe(b: &mut Bencher) {
-    const NTASK: u64 = 1000;
-
+fn contention_resubscribe<const N_TASKS: usize>(g: &mut BenchmarkGroup<WallTime>) {
     let rt = rt();
-    let (snd, rcv) = watch::channel(0i32);
+    let (snd, _) = watch::channel(0i32);
+    let snd = Arc::new(snd);
     let wg = Arc::new((AtomicU64::new(0), Notify::new()));
-    for n in 0..NTASK {
-        let mut rcv = rcv.clone();
+    for n in 0..N_TASKS {
+        let mut rcv = snd.subscribe();
         let wg = wg.clone();
-        let mut rng = rand::rngs::StdRng::seed_from_u64(n);
+        let mut rng = rand::rngs::StdRng::seed_from_u64(n as u64);
         rt.spawn(async move {
             while rcv.changed().await.is_ok() {
                 let _ = *rcv.borrow(); // contend on rwlock
@@ -46,19 +47,39 @@ fn contention_resubscribe(b: &mut Bencher) {
         });
     }
 
-    b.iter(|| {
-        rt.block_on(async {
-            for _ in 0..100 {
-                assert_eq!(wg.0.fetch_add(NTASK, Ordering::Relaxed), 0);
-                let _ = snd.send(black_box(42));
-                while wg.0.load(Ordering::Acquire) > 0 {
-                    wg.1.notified().await;
+    const N_ITERS: usize = 100;
+    g.bench_function(N_TASKS.to_string(), |b| {
+        b.iter(|| {
+            rt.block_on({
+                let snd = snd.clone();
+                let wg = wg.clone();
+                async move {
+                    tokio::spawn(async move {
+                        for _ in 0..N_ITERS {
+                            assert_eq!(wg.0.fetch_add(N_TASKS as u64, Ordering::Relaxed), 0);
+                            let _ = snd.send(black_box(42));
+                            while wg.0.load(Ordering::Acquire) > 0 {
+                                wg.1.notified().await;
+                            }
+                        }
+                    })
+                    .await
+                    .unwrap();
                 }
-            }
-        });
+            });
+        })
     });
 }
 
-bencher::benchmark_group!(contention, contention_resubscribe);
+fn bench_contention_resubscribe(c: &mut Criterion) {
+    let mut group = c.benchmark_group("contention_resubscribe");
+    contention_resubscribe::<10>(&mut group);
+    contention_resubscribe::<100>(&mut group);
+    contention_resubscribe::<500>(&mut group);
+    contention_resubscribe::<1000>(&mut group);
+    group.finish();
+}
 
-bencher::benchmark_main!(contention);
+criterion_group!(contention, bench_contention_resubscribe);
+
+criterion_main!(contention);

benches/time_now.rs

@@ -2,24 +2,23 @@
 //! This essentially measure the time to enqueue a task in the local and remote
 //! case.
 
-#[macro_use]
-extern crate bencher;
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
 
-use bencher::{black_box, Bencher};
-
-fn time_now_current_thread(bench: &mut Bencher) {
+fn time_now_current_thread(c: &mut Criterion) {
     let rt = tokio::runtime::Builder::new_current_thread()
         .enable_time()
         .build()
         .unwrap();
 
-    bench.iter(|| {
-        rt.block_on(async {
-            black_box(tokio::time::Instant::now());
+    c.bench_function("time_now_current_thread", |b| {
+        b.iter(|| {
+            rt.block_on(async {
+                black_box(tokio::time::Instant::now());
+            })
         })
-    })
+    });
 }
 
-bencher::benchmark_group!(time_now, time_now_current_thread,);
+criterion_group!(time_now, time_now_current_thread);
 
-bencher::benchmark_main!(time_now);
+criterion_main!(time_now);

bin/publish

@@ -1,121 +0,0 @@
-#!/usr/bin/env bash
-set -e
-USAGE="Publish a new release of a tokio crate
-
-USAGE:
-    $(basename "$0") [OPTIONS] [CRATE] [VERSION]
-
-OPTIONS:
-    -v, --verbose   Use verbose Cargo output
-    -d, --dry-run   Perform a dry run (do not publish or tag the release)
-    -h, --help      Show this help text and exit"
-
-DRY_RUN=""
-VERBOSE=""
-
-err() {
-    echo -e "\e[31m\e[1merror:\e[0m $@" 1>&2;
-}
-
-status() {
-    WIDTH=12
-    printf "\e[32m\e[1m%${WIDTH}s\e[0m %s\n" "$1" "$2"
-}
-
-verify() {
-    status "Verifying" "if $CRATE v$VERSION can be released"
-    ACTUAL=$(cargo pkgid | sed -n 's/.*#\(.*\)/\1/p')
-
-    if [ "$ACTUAL" != "$VERSION" ]; then
-        err "expected to release version $VERSION, but Cargo.toml contained $ACTUAL"
-        exit 1
-    fi
-
-    if git tag -l | grep -Fxq "$TAG" ; then
-        err "git tag \`$TAG\` already exists"
-        exit 1
-    fi
-
-    PATH_DEPS=$(grep -F "path = \"" Cargo.toml | sed -e 's/^/  /')
-    if [ -n "$PATH_DEPS" ]; then
-        err "crate \`$CRATE\` contained path dependencies:\n$PATH_DEPS"
-        echo "path dependencies must be removed prior to release"
-        exit 1
-    fi
-}
-
-release() {
-    status "Releasing" "$CRATE v$VERSION"
-    cargo package $VERBOSE
-    cargo publish $VERBOSE $DRY_RUN
-
-    status "Tagging" "$TAG"
-    if [ -n "$DRY_RUN" ]; then
-        echo "# git tag $TAG && git push --tags"
-    else
-        git tag "$TAG" && git push --tags
-    fi
-}
-
-while [[ $# -gt 0 ]]
-do
-
-case "$1" in
-    -h|--help)
-    echo "$USAGE"
-    exit 0
-    ;;
-    -v|--verbose)
-    VERBOSE="--verbose"
-    set +x
-    shift
-    ;;
-    -d|--dry-run)
-    DRY_RUN="--dry-run"
-    shift
-    ;;
-    -*)
-    err "unknown flag \"$1\""
-    echo "$USAGE"
-    exit 1
-    ;;
-    *) # crate or version
-    if [ -z "$CRATE" ]; then
-        CRATE="$1"
-    elif [ -z "$VERSION" ]; then
-        VERSION="$1"
-    else
-        err "unknown positional argument \"$1\""
-        echo "$USAGE"
-        exit 1
-    fi
-    shift
-    ;;
-esac
-done
-# set -- "${POSITIONAL[@]}"
-
-if [ -z "$VERSION" ]; then
-    err "no version specified!"
-    HELP=1
-fi
-
-if [ -n "$CRATE" ]; then
-    TAG="$CRATE-$VERSION"
-else
-    err "no crate specified!"
-    HELP=1
-fi
-
-if [ -n "$HELP" ]; then
-    echo "$USAGE"
-    exit 1
-fi
-
-if [ -d "$CRATE" ]; then
-    (cd "$CRATE" && verify && release )
-else
-    err "no such crate \"$CRATE\""
-    exit 1
-fi
-

bin/update-doc

@@ -1,118 +0,0 @@
-#!/usr/bin/env bash
-set -e
-USAGE="Update links to docs.rs in a tokio crate
-
-USAGE:
-    $(basename "$0") [OPTIONS] [CRATE] [VERSION]
-
-OPTIONS:
-    -d, --dry-run       Perform a dry run (do not modify any file)
-    -h, --help          Show this help text and exit"
-
-err() {
-    echo -e "\e[31m\e[1merror:\e[0m $@" 1>&2;
-}
-
-status() {
-    WIDTH=12
-    printf "\e[32m\e[1m%${WIDTH}s\e[0m %s\n" "$1" "$2"
-}
-
-c1grep() { grep "$@" || test $? = 1; }
-
-update_versions_in_doc() {
-    # Print what is being/would be done
-    if [ -n "$DRY_RUN" ]; then
-        local MSG="Would change:"
-    else
-        local MSG="Updating:"
-    fi
-    git grep -lr "docs.rs/$CRATE/" \
-        | xargs sed --quiet \
-            -E "s|docs.rs/$CRATE/[0-9.]+|docs.rs/$CRATE/$VERSION|gp" \
-        | sed -e "s/^/$MSG /"
-
-    # Apply changes if not in dry run
-    if [ -z "$DRY_RUN" ]; then
-        git grep -lr "docs.rs/$CRATE/" \
-            | xargs sed -i \
-                -E "s|docs.rs/$CRATE/[0-9.]+|docs.rs/$CRATE/$VERSION|g"
-    fi
-}
-
-update() {
-    update_versions_in_doc
-}
-
-show_outdated() {
-    OUTDATED=$(git grep -rn "docs.rs/$CRATE/" \
-        | c1grep -v "$VERSION" \
-        | sed -e 's/^/ - /')
-    if [[ -n "$OUTDATED" ]]; then
-        echo "Found the following links to docs.rs with an outdated version:"
-        echo "$OUTDATED"
-        echo
-    else
-        echo "Nothing to do."
-        exit 1
-    fi
-}
-
-while [[ $# -gt 0 ]]
-do
-
-case "$1" in
-    -h|--help)
-    echo "$USAGE"
-    exit 0
-    ;;
-    -d|--dry-run)
-    DRY_RUN="--dry-run"
-    shift
-    ;;
-    -*)
-    err "unknown flag \"$1\""
-    echo "$USAGE"
-    exit 1
-    ;;
-    *) # crate or version
-    if [ -z "$CRATE" ]; then
-        CRATE="$1"
-    elif [ -z "$VERSION" ]; then
-        VERSION="$1"
-    else
-        err "unknown positional argument \"$1\""
-        echo "$USAGE"
-        exit 1
-    fi
-    shift
-    ;;
-esac
-done
-# set -- "${POSITIONAL[@]}"
-
-if [ -z "$VERSION" ]; then
-    err "no version specified!"
-    HELP=1
-fi
-
-if [ -n "$CRATE" ]; then
-    TAG="$CRATE-$VERSION"
-else
-    err "no crate specified!"
-    HELP=1
-fi
-
-if [ -n "$HELP" ]; then
-    echo "$USAGE"
-    exit 1
-fi
-
-if [ -d "$CRATE" ]; then
-    # Does not cd in order to update everywhere
-    show_outdated && update
-else
-    err "no such crate \"$CRATE\""
-    exit 1
-fi
-

examples/Cargo.toml

@@ -2,7 +2,7 @@
 name = "examples"
 version = "0.0.0"
 publish = false
-edition = "2018"
+edition = "2021"
 
 # If you copy one of the examples into a new project, you should be using
 # [dependencies] instead, and delete the **path**.

examples/custom-executor-tokio-context.rs

@@ -23,7 +23,7 @@ fn main() {
 
     // Without the `HandleExt.wrap()` there would be a panic because there is
     // no timer running, since it would be referencing runtime r1.
-    let _ = rt1.block_on(rt2.wrap(async move {
+    rt1.block_on(rt2.wrap(async move {
         let listener = TcpListener::bind("0.0.0.0:0").await.unwrap();
         println!("addr: {:?}", listener.local_addr());
         tx.send(()).unwrap();

examples/dump.rs

@@ -1,4 +1,6 @@
-//! This example demonstrates tokio's experimental taskdumping functionality.
+//! This example demonstrates tokio's experimental task dumping functionality.
+//! This application deadlocks. Input CTRL+C to display traces of each task, or
+//! input CTRL+C twice within 1 second to quit.
 
 #[cfg(all(
     tokio_unstable,
@@ -6,37 +8,76 @@
     target_os = "linux",
     any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
 ))]
-#[tokio::main(flavor = "current_thread")]
-async fn main() {
-    use std::hint::black_box;
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    use std::sync::Arc;
+    use tokio::sync::Barrier;
 
     #[inline(never)]
-    async fn a() {
-        black_box(b()).await
+    async fn a(barrier: Arc<Barrier>) {
+        b(barrier).await
     }
 
     #[inline(never)]
-    async fn b() {
-        black_box(c()).await
+    async fn b(barrier: Arc<Barrier>) {
+        c(barrier).await
     }
 
     #[inline(never)]
-    async fn c() {
-        black_box(tokio::task::yield_now()).await
+    async fn c(barrier: Arc<Barrier>) {
+        barrier.wait().await;
     }
 
-    tokio::spawn(a());
-    tokio::spawn(b());
-    tokio::spawn(c());
+    // Prints a task dump upon receipt of CTRL+C, or returns if CTRL+C is
+    // inputted twice within a second.
+    async fn dump_or_quit() {
+        use tokio::time::{timeout, Duration, Instant};
+        let handle = tokio::runtime::Handle::current();
+        let mut last_signal: Option<Instant> = None;
+        // wait for CTRL+C
+        while let Ok(_) = tokio::signal::ctrl_c().await {
+            // exit if a CTRL+C is inputted twice within 1 second
+            if let Some(time_since_last_signal) = last_signal.map(|i| i.elapsed()) {
+                if time_since_last_signal < Duration::from_secs(1) {
+                    return;
+                }
+            }
+            last_signal = Some(Instant::now());
 
-    let handle = tokio::runtime::Handle::current();
-    let dump = handle.dump();
-
-    for (i, task) in dump.tasks().iter().enumerate() {
-        let trace = task.trace();
-        println!("task {i} trace:");
-        println!("{trace}");
+            // capture a dump, and print each trace
+            println!("{:-<80}", "");
+            if let Ok(dump) = timeout(Duration::from_secs(2), handle.dump()).await {
+                for task in dump.tasks().iter() {
+                    let id = task.id();
+                    let trace = task.trace();
+                    println!("TASK {id}:");
+                    println!("{trace}\n");
+                }
+            } else {
+                println!("Task dumping timed out. Use a native debugger (like gdb) to debug the deadlock.");
+            }
+            println!("{:-<80}", "");
+            println!("Input CTRL+C twice within 1 second to exit.");
+        }
     }
+
+    println!("This program has a deadlock.");
+    println!("Input CTRL+C to print a task dump.");
+    println!("Input CTRL+C twice within 1 second to exit.");
+
+    // oops! this barrier waits for one more task than will ever come.
+    let barrier = Arc::new(Barrier::new(3));
+
+    let task_1 = tokio::spawn(a(barrier.clone()));
+    let task_2 = tokio::spawn(a(barrier));
+
+    tokio::select!(
+        _ = dump_or_quit() => {},
+        _ = task_1 => {},
+        _ = task_2 => {},
+    );
+
+    Ok(())
 }
 
 #[cfg(not(all(

examples/proxy.rs

@@ -22,8 +22,7 @@
 
 #![warn(rust_2018_idioms)]
 
-use tokio::io;
-use tokio::io::AsyncWriteExt;
+use tokio::io::copy_bidirectional;
 use tokio::net::{TcpListener, TcpStream};
 
 use futures::FutureExt;
@@ -44,36 +43,19 @@ async fn main() -> Result<(), Box<dyn Error>> {
 
     let listener = TcpListener::bind(listen_addr).await?;
 
-    while let Ok((inbound, _)) = listener.accept().await {
-        let transfer = transfer(inbound, server_addr.clone()).map(|r| {
-            if let Err(e) = r {
-                println!("Failed to transfer; error={}", e);
-            }
-        });
+    while let Ok((mut inbound, _)) = listener.accept().await {
+        let mut outbound = TcpStream::connect(server_addr.clone()).await?;
 
-        tokio::spawn(transfer);
+        tokio::spawn(async move {
+            copy_bidirectional(&mut inbound, &mut outbound)
+                .map(|r| {
+                    if let Err(e) = r {
+                        println!("Failed to transfer; error={}", e);
+                    }
+                })
+                .await
+        });
     }
 
     Ok(())
 }
-
-async fn transfer(mut inbound: TcpStream, proxy_addr: String) -> Result<(), Box<dyn Error>> {
-    let mut outbound = TcpStream::connect(proxy_addr).await?;
-
-    let (mut ri, mut wi) = inbound.split();
-    let (mut ro, mut wo) = outbound.split();
-
-    let client_to_server = async {
-        io::copy(&mut ri, &mut wo).await?;
-        wo.shutdown().await
-    };
-
-    let server_to_client = async {
-        io::copy(&mut ro, &mut wi).await?;
-        wi.shutdown().await
-    };
-
-    tokio::try_join!(client_to_server, server_to_client)?;
-
-    Ok(())
-}

examples/tinyhttp.rs

@@ -18,7 +18,7 @@ use futures::SinkExt;
 use http::{header::HeaderValue, Request, Response, StatusCode};
 #[macro_use]
 extern crate serde_derive;
-use std::{convert::TryFrom, env, error::Error, fmt, io};
+use std::{env, error::Error, fmt, io};
 use tokio::net::{TcpListener, TcpStream};
 use tokio_stream::StreamExt;
 use tokio_util::codec::{Decoder, Encoder, Framed};

netlify.toml

@@ -8,8 +8,9 @@
   RUSTDOCFLAGS="""
     --cfg docsrs \
     --cfg tokio_unstable \
+    --cfg tokio_taskdump \
     """
-  RUSTFLAGS="--cfg tokio_unstable --cfg docsrs"
+  RUSTFLAGS="--cfg tokio_unstable --cfg tokio_taskdump --cfg docsrs"
 
 [[redirects]]
   from = "/"

spellcheck.dic

@@ -0,0 +1,283 @@
+283
+&
++
+<
+=
+>
+\
+~
+—
+0o777
+0s
+0xA
+0xD
+100ms
+10ms
+~12
+±1m
+±1ms
+1ms
+1s
+250ms
+2x
+~4
+443
+450ms
+50ms
+8MB
+adaptor
+adaptors
+Adaptors
+AIO
+ambiant
+amongst
+api
+APIs
+async
+awaitable
+backend
+backpressure
+backtrace
+backtraces
+backtracing
+binded
+bitfield
+bitfields
+Blockingly
+boolean
+broadcasted
+cancelled
+cancelling
+Cancelling
+CLI
+cloneable
+codebase
+codec
+codecs
+combinator
+combinators
+config
+Config
+connectionless
+coroutines
+cpu
+cpus
+Customizable
+datagram
+Datagram
+datagrams
+deallocate
+deallocated
+Deallocates
+decrementing
+dequeued
+deregister
+deregistered
+deregistering
+deregisters
+Deregisters
+deregistration
+descriptor's
+destructor
+destructors
+destructure
+Destructures
+Dev
+dns
+DNS
+DoS
+dwOpenMode
+endian
+enqueue
+enqueued
+EntryInner
+enum
+eof
+Erlang's
+errored
+EWMA
+expirations
+fcntl
+fd's
+FIFOs
+filename
+filesystem
+filesystems
+fn
+fns
+FreeBSD
+frontend
+fs
+functionalities
+getters
+GID
+goroutines
+Growable
+gzip
+hashmaps
+HashMaps
+hashsets
+ie
+Illumos
+impl
+implementers
+implementor
+implementors
+incrementing
+interoperate
+invariants
+Invariants
+io
+IOCP
+iOS
+IOs
+IP
+IPv4
+IPv6
+iteratively
+Kotlin's
+latencies
+Lauck
+libc
+lifecycle
+lifo
+lookups
+macOS
+MacOS
+Marsaglia's
+metadata
+mio
+Mio
+mio's
+misconfigured
+mock's
+mpmc
+mpsc
+multi
+Multi
+multicast
+Multithreaded
+mut
+mutex
+Mutex
+Nagle
+nonblocking
+nondecreasing
+noop
+ntasks
+ok
+oneshot
+ORed
+os
+overweighing
+parker
+parsers
+peekable
+PGID
+PID
+plaintext
+poller
+POSIX
+proxied
+qos
+RAII
+reallocations
+recv's
+refactors
+refcount
+refcounting
+repo
+repr
+representable
+reqwest
+reregistering
+resize
+resized
+RMW
+runtime
+runtime's
+runtimes
+rwlock
+rx
+scalability
+scheduler's
+semver
+setpgid
+sharded
+signalled
+signalling
+SmallCrush
+Solaris
+spawner
+Splitter
+spmc
+spsc
+src
+stabilised
+startup
+stateful
+stderr
+stdin
+stdout
+stealable
+stealer
+stealers
+struct
+structs
+subfield
+suboptimal
+subprocess
+superset
+symlink
+symlinks
+sys
+syscall
+syscalls
+tcp
+TCP
+TestU01
+threadpool
+timestamp
+timestamps
+TLS
+TOCTOU
+TODO
+tokio
+Tokio
+tokio's
+Tokio's
+tuple
+Tuple
+tx
+udp
+UDP
+UID
+unhandled
+unix
+unlink
+unpark
+Unpark
+unparked
+unparking
+unparks
+Unparks
+unreceived
+unsafety
+Unsets
+unsynchronized
+untrusted
+usecases
+Valgrind
+Varghese
+vec
+versa
+versioned
+versioning
+vtable
+waker
+wakers
+Wakers
+wakeup
+wakeups
+workstealing
+

spellcheck.toml

@@ -0,0 +1,13 @@
+dev_comments = false
+skip_readme = false
+
+[Hunspell]
+lang = "en_US"
+search_dirs = ["."]
+extra_dictionaries = ["spellcheck.dic"]
+skip_os_lookups = true
+use_builtin = true
+
+[Hunspell.quirks]
+allow_concatenation = true
+

stress-test/Cargo.toml

@@ -2,7 +2,7 @@
 name = "stress-test"
 version = "0.1.0"
 authors = ["Tokio Contributors <[email protected]>"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

stress-test/examples/simple_echo_tcp.rs

@@ -42,7 +42,7 @@ fn main() {
                 .write_all(one_mega_random_bytes.as_slice())
                 .await
                 .unwrap();
-            stream.read(&mut buff).await.unwrap();
+            let _ = stream.read(&mut buff).await.unwrap();
         }
         tx.send(()).unwrap();
     });

tests-build/Cargo.toml

@@ -2,7 +2,7 @@
 name = "tests-build"
 version = "0.1.0"
 authors = ["Tokio Contributors <[email protected]>"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [features]

tests-build/tests/fail/macros_type_mismatch.stderr

@@ -1,24 +1,36 @@
 error[E0308]: mismatched types
  --> tests/fail/macros_type_mismatch.rs:5:5
   |
-4 | async fn missing_semicolon_or_return_type() {
-  |                                             - help: a return type might be missing here: `-> _`
 5 |     Ok(())
   |     ^^^^^^ expected `()`, found `Result<(), _>`
   |
   = note: expected unit type `()`
                   found enum `Result<(), _>`
+help: a return type might be missing here
+  |
+4 | async fn missing_semicolon_or_return_type() -> _ {
+  |                                             ++++
+help: consider using `Result::expect` to unwrap the `Result<(), _>` value, panicking if the value is a `Result::Err`
+  |
+5 |     Ok(()).expect("REASON")
+  |           +++++++++++++++++
 
 error[E0308]: mismatched types
   --> tests/fail/macros_type_mismatch.rs:10:5
    |
-9  | async fn missing_return_type() {
-   |                                - help: a return type might be missing here: `-> _`
 10 |     return Ok(());
    |     ^^^^^^^^^^^^^^ expected `()`, found `Result<(), _>`
    |
    = note: expected unit type `()`
                    found enum `Result<(), _>`
+help: a return type might be missing here
+   |
+9  | async fn missing_return_type() -> _ {
+   |                                ++++
+help: consider using `Result::expect` to unwrap the `Result<(), _>` value, panicking if the value is a `Result::Err`
+   |
+10 |     return Ok(());.expect("REASON")
+   |                   +++++++++++++++++
 
 error[E0308]: mismatched types
   --> tests/fail/macros_type_mismatch.rs:23:5
@@ -41,7 +53,7 @@ error[E0308]: mismatched types
   --> tests/fail/macros_type_mismatch.rs:32:5
    |
 30 | async fn issue_4635() {
-   |                       - help: try adding a return type: `-> i32`
+   |                      - help: try adding a return type: `-> i32`
 31 |     return 1;
 32 |     ;
    |     ^ expected `()`, found integer

tests-integration/Cargo.toml

@@ -2,7 +2,7 @@
 name = "tests-integration"
 version = "0.1.0"
 authors = ["Tokio Contributors <[email protected]>"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [[bin]]

tests-integration/tests/process_stdio.rs

@@ -7,7 +7,6 @@ use tokio::process::{Child, Command};
 use tokio_test::assert_ok;
 
 use futures::future::{self, FutureExt};
-use std::convert::TryInto;
 use std::env;
 use std::io;
 use std::process::{ExitStatus, Stdio};

tokio-macros/CHANGELOG.md

@@ -1,3 +1,11 @@
+# 2.2.0 (November 19th, 2023)
+
+### Changed
+
+- use `::core` qualified imports instead of `::std` inside `tokio::test` macro ([#5973])
+
+[#5973]: https://github.com/tokio-rs/tokio/pull/5973
+
 # 2.1.0 (April 25th, 2023)
 
 - macros: fix typo in `#[tokio::test]` docs ([#5636])

tokio-macros/Cargo.toml

@@ -4,9 +4,9 @@ name = "tokio-macros"
 # - Remove path dependencies
 # - Update CHANGELOG.md.
 # - Create "tokio-macros-1.x.y" git tag.
-version = "2.1.0"
-edition = "2018"
-rust-version = "1.56"
+version = "2.2.0"
+edition = "2021"
+rust-version = "1.63"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
@@ -22,7 +22,7 @@ proc-macro = true
 [features]
 
 [dependencies]
-proc-macro2 = "1.0.7"
+proc-macro2 = "1.0.60"
 quote = "1"
 syn = { version = "2.0", features = ["full"] }
 

tokio-macros/src/entry.rs

@@ -126,22 +126,22 @@ impl Configuration {
     }
 
     fn build(&self) -> Result<FinalConfig, syn::Error> {
-        let flavor = self.flavor.unwrap_or(self.default_flavor);
-        use RuntimeFlavor::*;
+        use RuntimeFlavor as F;
 
+        let flavor = self.flavor.unwrap_or(self.default_flavor);
         let worker_threads = match (flavor, self.worker_threads) {
-            (CurrentThread, Some((_, worker_threads_span))) => {
+            (F::CurrentThread, Some((_, worker_threads_span))) => {
                 let msg = format!(
                     "The `worker_threads` option requires the `multi_thread` runtime flavor. Use `#[{}(flavor = \"multi_thread\")]`",
                     self.macro_name(),
                 );
                 return Err(syn::Error::new(worker_threads_span, msg));
             }
-            (CurrentThread, None) => None,
-            (Threaded, worker_threads) if self.rt_multi_thread_available => {
+            (F::CurrentThread, None) => None,
+            (F::Threaded, worker_threads) if self.rt_multi_thread_available => {
                 worker_threads.map(|(val, _span)| val)
             }
-            (Threaded, _) => {
+            (F::Threaded, _) => {
                 let msg = if self.flavor.is_none() {
                     "The default runtime flavor is `multi_thread`, but the `rt-multi-thread` feature is disabled."
                 } else {
@@ -152,14 +152,14 @@ impl Configuration {
         };
 
         let start_paused = match (flavor, self.start_paused) {
-            (Threaded, Some((_, start_paused_span))) => {
+            (F::Threaded, Some((_, start_paused_span))) => {
                 let msg = format!(
                     "The `start_paused` option requires the `current_thread` runtime flavor. Use `#[{}(flavor = \"current_thread\")]`",
                     self.macro_name(),
                 );
                 return Err(syn::Error::new(start_paused_span, msg));
             }
-            (CurrentThread, Some((start_paused, _))) => Some(start_paused),
+            (F::CurrentThread, Some((start_paused, _))) => Some(start_paused),
             (_, None) => None,
         };
 
@@ -402,7 +402,7 @@ fn parse_knobs(mut input: ItemFn, is_test: bool, config: FinalConfig) -> TokenSt
         quote! {
             let body = async #body;
             #crate_path::pin!(body);
-            let body: ::std::pin::Pin<&mut dyn ::std::future::Future<Output = #output_type>> = body;
+            let body: ::core::pin::Pin<&mut dyn ::core::future::Future<Output = #output_type>> = body;
         }
     } else {
         quote! {
@@ -507,7 +507,7 @@ impl ItemFn {
 
         // Inner attributes require extra care, since they're not supported on
         // blocks (which is what we're expanded into) we instead lift them
-        // outside of the function. This matches the behaviour of `syn`.
+        // outside of the function. This matches the behavior of `syn`.
         for mut attr in self.inner_attrs {
             attr.style = syn::AttrStyle::Outer;
             attr.to_tokens(&mut tokens);
@@ -586,6 +586,6 @@ impl ToTokens for Body<'_> {
             for stmt in self.stmts {
                 stmt.to_tokens(tokens);
             }
-        })
+        });
     }
 }

tokio-macros/src/select.rs

@@ -73,27 +73,27 @@ fn clean_pattern(pat: &mut syn::Pat) {
             }
         }
         syn::Pat::Or(or) => {
-            for case in or.cases.iter_mut() {
+            for case in &mut or.cases {
                 clean_pattern(case);
             }
         }
         syn::Pat::Slice(slice) => {
-            for elem in slice.elems.iter_mut() {
+            for elem in &mut slice.elems {
                 clean_pattern(elem);
             }
         }
         syn::Pat::Struct(struct_pat) => {
-            for field in struct_pat.fields.iter_mut() {
+            for field in &mut struct_pat.fields {
                 clean_pattern(&mut field.pat);
             }
         }
         syn::Pat::Tuple(tuple) => {
-            for elem in tuple.elems.iter_mut() {
+            for elem in &mut tuple.elems {
                 clean_pattern(elem);
             }
         }
         syn::Pat::TupleStruct(tuple) => {
-            for elem in tuple.elems.iter_mut() {
+            for elem in &mut tuple.elems {
                 clean_pattern(elem);
             }
         }

tokio-stream/CHANGELOG.md

@@ -1,3 +1,19 @@
+# 0.1.15 (March 14th, 2024)
+
+This release bumps the MSRV of tokio-stream to 1.63.
+
+- docs: fix typo in argument name ([#6389])
+- docs: fix typo in peekable docs ([#6130])
+- docs: link to latest version of tokio-util docs ([#5694])
+- docs: typographic improvements ([#6262])
+- stream: add `StreamExt::peekable` ([#6095])
+
+[#5694]: https://github.com/tokio-rs/tokio/pull/5694
+[#6095]: https://github.com/tokio-rs/tokio/pull/6095
+[#6130]: https://github.com/tokio-rs/tokio/pull/6130
+[#6262]: https://github.com/tokio-rs/tokio/pull/6262
+[#6389]: https://github.com/tokio-rs/tokio/pull/6389
+
 # 0.1.14 (April 26th, 2023)
 
 This bugfix release bumps the minimum version of Tokio to 1.15, which is

tokio-stream/Cargo.toml

@@ -4,9 +4,9 @@ name = "tokio-stream"
 # - Remove path dependencies
 # - Update CHANGELOG.md.
 # - Create "tokio-stream-0.1.x" git tag.
-version = "0.1.14"
+version = "0.1.15"
 edition = "2021"
-rust-version = "1.56"
+rust-version = "1.63"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
@@ -37,7 +37,7 @@ signal = ["tokio/signal"]
 
 [dependencies]
 futures-core = { version = "0.3.0" }
-pin-project-lite = "0.2.0"
+pin-project-lite = "0.2.11"
 tokio = { version = "1.15.0", path = "../tokio", features = ["sync"] }
 tokio-util = { version = "0.7.0", path = "../tokio-util", optional = true }
 

tokio-stream/fuzz/Cargo.toml

@@ -2,7 +2,7 @@
 name = "tokio-stream-fuzz"
 version = "0.0.0"
 publish = false
-edition = "2018"
+edition = "2021"
 
 [package.metadata]
 cargo-fuzz = true

tokio-stream/src/lib.rs

@@ -54,7 +54,7 @@
 //!
 //! [async-stream]: https://docs.rs/async-stream
 //!
-//! # Conversion to and from AsyncRead/AsyncWrite
+//! # Conversion to and from `AsyncRead`/`AsyncWrite`
 //!
 //! It is often desirable to convert a `Stream` into an [`AsyncRead`],
 //! especially when dealing with plaintext formats streamed over the network.
@@ -73,6 +73,9 @@
 #[macro_use]
 mod macros;
 
+mod poll_fn;
+pub(crate) use poll_fn::poll_fn;
+
 pub mod wrappers;
 
 mod stream_ext;

tokio-stream/src/once.rs

@@ -35,7 +35,7 @@ impl<I> Unpin for Once<I> {}
 /// ```
 pub fn once<T>(value: T) -> Once<T> {
     Once {
-        iter: crate::iter(Some(value).into_iter()),
+        iter: crate::iter(Some(value)),
     }
 }
 

tokio-stream/src/poll_fn.rs

@@ -0,0 +1,35 @@
+use std::future::Future;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+pub(crate) struct PollFn<F> {
+    f: F,
+}
+
+pub(crate) fn poll_fn<T, F>(f: F) -> PollFn<F>
+where
+    F: FnMut(&mut Context<'_>) -> Poll<T>,
+{
+    PollFn { f }
+}
+
+impl<T, F> Future for PollFn<F>
+where
+    F: FnMut(&mut Context<'_>) -> Poll<T>,
+{
+    type Output = T;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
+        // Safety: We never construct a `Pin<&mut F>` anywhere, so accessing `f`
+        // mutably in an unpinned way is sound.
+        //
+        // This use of unsafe cannot be replaced with the pin-project macro
+        // because:
+        //  * If we put `#[pin]` on the field, then it gives us a `Pin<&mut F>`,
+        //    which we can't use to call the closure.
+        //  * If we don't put `#[pin]` on the field, then it makes `PollFn` be
+        //    unconditionally `Unpin`, which we also don't want.
+        let me = unsafe { Pin::into_inner_unchecked(self) };
+        (me.f)(cx)
+    }
+}

tokio-stream/src/stream_ext.rs

@@ -55,6 +55,9 @@ use then::Then;
 mod try_next;
 use try_next::TryNext;
 
+mod peekable;
+use peekable::Peekable;
+
 cfg_time! {
     pub(crate) mod timeout;
     pub(crate) mod timeout_repeating;
@@ -848,8 +851,7 @@ pub trait StreamExt: Stream {
     ///
     /// `collect` streams all values, awaiting as needed. Values are pushed into
     /// a collection. A number of different target collection types are
-    /// supported, including [`Vec`](std::vec::Vec),
-    /// [`String`](std::string::String), and [`Bytes`].
+    /// supported, including [`Vec`], [`String`], and [`Bytes`].
     ///
     /// [`Bytes`]: https://docs.rs/bytes/0.6.0/bytes/struct.Bytes.html
     ///
@@ -994,7 +996,7 @@ pub trait StreamExt: Stream {
     /// assert!(timeout_stream.try_next().await.is_ok(), "expected no more timeouts");
     /// # }
     /// ```
-    #[cfg(all(feature = "time"))]
+    #[cfg(feature = "time")]
     #[cfg_attr(docsrs, doc(cfg(feature = "time")))]
     fn timeout(self, duration: Duration) -> Timeout<Self>
     where
@@ -1005,9 +1007,8 @@ pub trait StreamExt: Stream {
 
     /// Applies a per-item timeout to the passed stream.
     ///
-    /// `timeout_repeating()` takes an [`Interval`](tokio::time::Interval) that
-    /// controls the time each element of the stream has to complete before
-    /// timing out.
+    /// `timeout_repeating()` takes an [`Interval`] that controls the time each
+    /// element of the stream has to complete before timing out.
     ///
     /// If the wrapped stream yields a value before the deadline is reached, the
     /// value is returned. Otherwise, an error is returned. The caller may decide
@@ -1083,7 +1084,7 @@ pub trait StreamExt: Stream {
     /// assert!(timeout_stream.try_next().await.is_ok(), "expected non-timeout");
     /// # }
     /// ```
-    #[cfg(all(feature = "time"))]
+    #[cfg(feature = "time")]
     #[cfg_attr(docsrs, doc(cfg(feature = "time")))]
     fn timeout_repeating(self, interval: Interval) -> TimeoutRepeating<Self>
     where
@@ -1113,7 +1114,7 @@ pub trait StreamExt: Stream {
     /// }
     /// # }
     /// ```
-    #[cfg(all(feature = "time"))]
+    #[cfg(feature = "time")]
     #[cfg_attr(docsrs, doc(cfg(feature = "time")))]
     fn throttle(self, duration: Duration) -> Throttle<Self>
     where
@@ -1178,6 +1179,31 @@ pub trait StreamExt: Stream {
         assert!(max_size > 0, "`max_size` must be non-zero.");
         ChunksTimeout::new(self, max_size, duration)
     }
+
+    /// Turns the stream into a peekable stream, whose next element can be peeked at without being
+    /// consumed.
+    /// ```rust
+    /// use tokio_stream::{self as stream, StreamExt};
+    ///
+    /// #[tokio::main]
+    /// # async fn _unused() {}
+    /// # #[tokio::main(flavor = "current_thread", start_paused = true)]
+    /// async fn main() {
+    ///     let iter = vec![1, 2, 3, 4].into_iter();
+    ///     let mut stream = stream::iter(iter).peekable();
+    ///
+    ///     assert_eq!(*stream.peek().await.unwrap(), 1);
+    ///     assert_eq!(*stream.peek().await.unwrap(), 1);
+    ///     assert_eq!(stream.next().await.unwrap(), 1);
+    ///     assert_eq!(*stream.peek().await.unwrap(), 2);
+    /// }
+    /// ```
+    fn peekable(self) -> Peekable<Self>
+    where
+        Self: Sized,
+    {
+        Peekable::new(self)
+    }
 }
 
 impl<St: ?Sized> StreamExt for St where St: Stream {}

tokio-stream/src/stream_ext/collect.rs

@@ -26,7 +26,7 @@ pin_project! {
     }
 }
 
-/// Convert from a [`Stream`](crate::Stream).
+/// Convert from a [`Stream`].
 ///
 /// This trait is not intended to be used directly. Instead, call
 /// [`StreamExt::collect()`](super::StreamExt::collect).

tokio-stream/src/stream_ext/merge.rs

@@ -66,25 +66,23 @@ where
     T: Stream,
     U: Stream<Item = T::Item>,
 {
-    use Poll::*;
-
     let mut done = true;
 
     match first.poll_next(cx) {
-        Ready(Some(val)) => return Ready(Some(val)),
-        Ready(None) => {}
-        Pending => done = false,
+        Poll::Ready(Some(val)) => return Poll::Ready(Some(val)),
+        Poll::Ready(None) => {}
+        Poll::Pending => done = false,
     }
 
     match second.poll_next(cx) {
-        Ready(Some(val)) => return Ready(Some(val)),
-        Ready(None) => {}
-        Pending => done = false,
+        Poll::Ready(Some(val)) => return Poll::Ready(Some(val)),
+        Poll::Ready(None) => {}
+        Poll::Pending => done = false,
     }
 
     if done {
-        Ready(None)
+        Poll::Ready(None)
     } else {
-        Pending
+        Poll::Pending
     }
 }

tokio-stream/src/stream_ext/peekable.rs

@@ -0,0 +1,50 @@
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+use futures_core::Stream;
+use pin_project_lite::pin_project;
+
+use crate::stream_ext::Fuse;
+use crate::StreamExt;
+
+pin_project! {
+    /// Stream returned by the [`chain`](super::StreamExt::peekable) method.
+    pub struct Peekable<T: Stream> {
+        peek: Option<T::Item>,
+        #[pin]
+        stream: Fuse<T>,
+    }
+}
+
+impl<T: Stream> Peekable<T> {
+    pub(crate) fn new(stream: T) -> Self {
+        let stream = stream.fuse();
+        Self { peek: None, stream }
+    }
+
+    /// Peek at the next item in the stream.
+    pub async fn peek(&mut self) -> Option<&T::Item>
+    where
+        T: Unpin,
+    {
+        if let Some(ref it) = self.peek {
+            Some(it)
+        } else {
+            self.peek = self.next().await;
+            self.peek.as_ref()
+        }
+    }
+}
+
+impl<T: Stream> Stream for Peekable<T> {
+    type Item = T::Item;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        let this = self.project();
+        if let Some(it) = this.peek.take() {
+            Poll::Ready(Some(it))
+        } else {
+            this.stream.poll_next(cx)
+        }
+    }
+}

tokio-stream/src/stream_ext/take.rs

@@ -64,11 +64,11 @@ where
 
         let (lower, upper) = self.stream.size_hint();
 
-        let lower = cmp::min(lower, self.remaining as usize);
+        let lower = cmp::min(lower, self.remaining);
 
         let upper = match upper {
-            Some(x) if x < self.remaining as usize => Some(x),
-            _ => Some(self.remaining as usize),
+            Some(x) if x < self.remaining => Some(x),
+            _ => Some(self.remaining),
         };
 
         (lower, upper)

tokio-stream/src/stream_map.rs

@@ -1,4 +1,4 @@
-use crate::Stream;
+use crate::{poll_fn, Stream};
 
 use std::borrow::Borrow;
 use std::hash::Hash;
@@ -209,7 +209,7 @@ pub struct StreamMap<K, V> {
 impl<K, V> StreamMap<K, V> {
     /// An iterator visiting all key-value pairs in arbitrary order.
     ///
-    /// The iterator element type is &'a (K, V).
+    /// The iterator element type is `&'a (K, V)`.
     ///
     /// # Examples
     ///
@@ -232,7 +232,7 @@ impl<K, V> StreamMap<K, V> {
 
     /// An iterator visiting all key-value pairs mutably in arbitrary order.
     ///
-    /// The iterator element type is &'a mut (K, V).
+    /// The iterator element type is `&'a mut (K, V)`.
     ///
     /// # Examples
     ///
@@ -289,7 +289,7 @@ impl<K, V> StreamMap<K, V> {
 
     /// Returns an iterator visiting all keys in arbitrary order.
     ///
-    /// The iterator element type is &'a K.
+    /// The iterator element type is `&'a K`.
     ///
     /// # Examples
     ///
@@ -312,7 +312,7 @@ impl<K, V> StreamMap<K, V> {
 
     /// An iterator visiting all values in arbitrary order.
     ///
-    /// The iterator element type is &'a V.
+    /// The iterator element type is `&'a V`.
     ///
     /// # Examples
     ///
@@ -335,7 +335,7 @@ impl<K, V> StreamMap<K, V> {
 
     /// An iterator visiting all values mutably in arbitrary order.
     ///
-    /// The iterator element type is &'a mut V.
+    /// The iterator element type is `&'a mut V`.
     ///
     /// # Examples
     ///
@@ -518,8 +518,6 @@ where
 {
     /// Polls the next value, includes the vec entry index
     fn poll_next_entry(&mut self, cx: &mut Context<'_>) -> Poll<Option<(usize, V::Item)>> {
-        use Poll::*;
-
         let start = self::rand::thread_rng_n(self.entries.len() as u32) as usize;
         let mut idx = start;
 
@@ -527,8 +525,8 @@ where
             let (_, stream) = &mut self.entries[idx];
 
             match Pin::new(stream).poll_next(cx) {
-                Ready(Some(val)) => return Ready(Some((idx, val))),
-                Ready(None) => {
+                Poll::Ready(Some(val)) => return Poll::Ready(Some((idx, val))),
+                Poll::Ready(None) => {
                     // Remove the entry
                     self.entries.swap_remove(idx);
 
@@ -542,7 +540,7 @@ where
                         idx = idx.wrapping_add(1) % self.entries.len();
                     }
                 }
-                Pending => {
+                Poll::Pending => {
                     idx = idx.wrapping_add(1) % self.entries.len();
                 }
             }
@@ -550,9 +548,9 @@ where
 
         // If the map is empty, then the stream is complete.
         if self.entries.is_empty() {
-            Ready(None)
+            Poll::Ready(None)
         } else {
-            Pending
+            Poll::Pending
         }
     }
 }
@@ -563,6 +561,110 @@ impl<K, V> Default for StreamMap<K, V> {
     }
 }
 
+impl<K, V> StreamMap<K, V>
+where
+    K: Clone + Unpin,
+    V: Stream + Unpin,
+{
+    /// Receives multiple items on this [`StreamMap`], extending the provided `buffer`.
+    ///
+    /// This method returns the number of items that is appended to the `buffer`.
+    ///
+    /// Note that this method does not guarantee that exactly `limit` items
+    /// are received. Rather, if at least one item is available, it returns
+    /// as many items as it can up to the given limit. This method returns
+    /// zero only if the `StreamMap` is empty (or if `limit` is zero).
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. If `next_many` is used as the event in a
+    /// [`tokio::select!`](tokio::select) statement and some other branch
+    /// completes first, it is guaranteed that no items were received on any of
+    /// the underlying streams.
+    pub async fn next_many(&mut self, buffer: &mut Vec<(K, V::Item)>, limit: usize) -> usize {
+        poll_fn(|cx| self.poll_next_many(cx, buffer, limit)).await
+    }
+
+    /// Polls to receive multiple items on this `StreamMap`, extending the provided `buffer`.
+    ///
+    /// This method returns:
+    /// * `Poll::Pending` if no items are available but the `StreamMap` is not empty.
+    /// * `Poll::Ready(count)` where `count` is the number of items successfully received and
+    ///   stored in `buffer`. This can be less than, or equal to, `limit`.
+    /// * `Poll::Ready(0)` if `limit` is set to zero or when the `StreamMap` is empty.
+    ///
+    /// Note that this method does not guarantee that exactly `limit` items
+    /// are received. Rather, if at least one item is available, it returns
+    /// as many items as it can up to the given limit. This method returns
+    /// zero only if the `StreamMap` is empty (or if `limit` is zero).
+    pub fn poll_next_many(
+        &mut self,
+        cx: &mut Context<'_>,
+        buffer: &mut Vec<(K, V::Item)>,
+        limit: usize,
+    ) -> Poll<usize> {
+        if limit == 0 || self.entries.is_empty() {
+            return Poll::Ready(0);
+        }
+
+        let mut added = 0;
+
+        let start = self::rand::thread_rng_n(self.entries.len() as u32) as usize;
+        let mut idx = start;
+
+        while added < limit {
+            // Indicates whether at least one stream returned a value when polled or not
+            let mut should_loop = false;
+
+            for _ in 0..self.entries.len() {
+                let (_, stream) = &mut self.entries[idx];
+
+                match Pin::new(stream).poll_next(cx) {
+                    Poll::Ready(Some(val)) => {
+                        added += 1;
+
+                        let key = self.entries[idx].0.clone();
+                        buffer.push((key, val));
+
+                        should_loop = true;
+
+                        idx = idx.wrapping_add(1) % self.entries.len();
+                    }
+                    Poll::Ready(None) => {
+                        // Remove the entry
+                        self.entries.swap_remove(idx);
+
+                        // Check if this was the last entry, if so the cursor needs
+                        // to wrap
+                        if idx == self.entries.len() {
+                            idx = 0;
+                        } else if idx < start && start <= self.entries.len() {
+                            // The stream being swapped into the current index has
+                            // already been polled, so skip it.
+                            idx = idx.wrapping_add(1) % self.entries.len();
+                        }
+                    }
+                    Poll::Pending => {
+                        idx = idx.wrapping_add(1) % self.entries.len();
+                    }
+                }
+            }
+
+            if !should_loop {
+                break;
+            }
+        }
+
+        if added > 0 {
+            Poll::Ready(added)
+        } else if self.entries.is_empty() {
+            Poll::Ready(0)
+        } else {
+            Poll::Pending
+        }
+    }
+}
+
 impl<K, V> Stream for StreamMap<K, V>
 where
     K: Clone + Unpin,
@@ -660,9 +762,9 @@ mod rand {
 
     /// Fast random number generate
     ///
-    /// Implement xorshift64+: 2 32-bit xorshift sequences added together.
+    /// Implement `xorshift64+`: 2 32-bit `xorshift` sequences added together.
     /// Shift triplet `[17,7,16]` was calculated as indicated in Marsaglia's
-    /// Xorshift paper: <https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf>
+    /// `Xorshift` paper: <https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf>
     /// This generator passes the SmallCrush suite, part of TestU01 framework:
     /// <http://simul.iro.umontreal.ca/testu01/tu01.html>
     #[derive(Debug)]

tokio-stream/src/wrappers/lines.rs

@@ -30,7 +30,6 @@ impl<R> LinesStream<R> {
     }
 
     /// Obtain a pinned reference to the inner `Lines<R>`.
-    #[allow(clippy::wrong_self_convention)] // https://github.com/rust-lang/rust-clippy/issues/4546
     pub fn as_pin_mut(self: Pin<&mut Self>) -> Pin<&mut Lines<R>> {
         self.project().inner
     }

tokio-stream/src/wrappers/mpsc_bounded.rs

@@ -34,7 +34,7 @@ impl<T> ReceiverStream<T> {
     ///
     /// [`Permit`]: struct@tokio::sync::mpsc::Permit
     pub fn close(&mut self) {
-        self.inner.close()
+        self.inner.close();
     }
 }
 

tokio-stream/src/wrappers/mpsc_unbounded.rs

@@ -28,7 +28,7 @@ impl<T> UnboundedReceiverStream<T> {
     /// 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) {
-        self.inner.close()
+        self.inner.close();
     }
 }
 

tokio-stream/src/wrappers/signal_unix.rs

@@ -15,8 +15,8 @@ pub struct SignalStream {
 
 impl SignalStream {
     /// Create a new `SignalStream`.
-    pub fn new(interval: Signal) -> Self {
-        Self { inner: interval }
+    pub fn new(signal: Signal) -> Self {
+        Self { inner: signal }
     }
 
     /// Get back the inner `Signal`.

tokio-stream/src/wrappers/split.rs

@@ -30,7 +30,6 @@ impl<R> SplitStream<R> {
     }
 
     /// Obtain a pinned reference to the inner `Split<R>`.
-    #[allow(clippy::wrong_self_convention)] // https://github.com/rust-lang/rust-clippy/issues/4546
     pub fn as_pin_mut(self: Pin<&mut Self>) -> Pin<&mut Split<R>> {
         self.project().inner
     }

tokio-stream/src/wrappers/watch.rs

@@ -10,7 +10,7 @@ use tokio::sync::watch::error::RecvError;
 
 /// A wrapper around [`tokio::sync::watch::Receiver`] that implements [`Stream`].
 ///
-/// This stream will start by yielding the current value when the WatchStream is polled,
+/// This stream will start by yielding the current value when the `WatchStream` is polled,
 /// regardless of whether it was the initial value or sent afterwards,
 /// unless you use [`WatchStream<T>::from_changes`].
 ///

tokio-stream/tests/stream_panic.rs

@@ -1,5 +1,6 @@
 #![warn(rust_2018_idioms)]
 #![cfg(all(feature = "time", not(target_os = "wasi")))] // Wasi does not support panic recovery
+#![cfg(panic = "unwind")]
 
 use parking_lot::{const_mutex, Mutex};
 use std::error::Error;

tokio-stream/tests/stream_stream_map.rs

@@ -1,14 +1,17 @@
+use futures::stream::iter;
 use tokio_stream::{self as stream, pending, Stream, StreamExt, StreamMap};
 use tokio_test::{assert_ok, assert_pending, assert_ready, task};
 
+use std::future::{poll_fn, Future};
+use std::pin::{pin, Pin};
+use std::task::Poll;
+
 mod support {
     pub(crate) mod mpsc;
 }
 
 use support::mpsc;
 
-use std::pin::Pin;
-
 macro_rules! assert_ready_some {
     ($($t:tt)*) => {
         match assert_ready!($($t)*) {
@@ -328,3 +331,233 @@ fn one_ready_many_none() {
 fn pin_box<T: Stream<Item = U> + 'static, U>(s: T) -> Pin<Box<dyn Stream<Item = U>>> {
     Box::pin(s)
 }
+
+type UsizeStream = Pin<Box<dyn Stream<Item = usize> + Send>>;
+
+#[tokio::test]
+async fn poll_next_many_zero() {
+    let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+    stream_map.insert(0, Box::pin(pending()) as UsizeStream);
+
+    let n = poll_fn(|cx| stream_map.poll_next_many(cx, &mut vec![], 0)).await;
+
+    assert_eq!(n, 0);
+}
+
+#[tokio::test]
+async fn poll_next_many_empty() {
+    let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+    let n = poll_fn(|cx| stream_map.poll_next_many(cx, &mut vec![], 1)).await;
+
+    assert_eq!(n, 0);
+}
+
+#[tokio::test]
+async fn poll_next_many_pending() {
+    let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+    stream_map.insert(0, Box::pin(pending()) as UsizeStream);
+
+    let mut is_pending = false;
+    poll_fn(|cx| {
+        let poll = stream_map.poll_next_many(cx, &mut vec![], 1);
+
+        is_pending = poll.is_pending();
+
+        Poll::Ready(())
+    })
+    .await;
+
+    assert!(is_pending);
+}
+
+#[tokio::test]
+async fn poll_next_many_not_enough() {
+    let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+    stream_map.insert(0, Box::pin(iter([0usize].into_iter())) as UsizeStream);
+    stream_map.insert(1, Box::pin(iter([1usize].into_iter())) as UsizeStream);
+
+    let mut buffer = vec![];
+    let n = poll_fn(|cx| stream_map.poll_next_many(cx, &mut buffer, 3)).await;
+
+    assert_eq!(n, 2);
+    assert_eq!(buffer.len(), 2);
+    assert!(buffer.contains(&(0, 0)));
+    assert!(buffer.contains(&(1, 1)));
+}
+
+#[tokio::test]
+async fn poll_next_many_enough() {
+    let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+    stream_map.insert(0, Box::pin(iter([0usize].into_iter())) as UsizeStream);
+    stream_map.insert(1, Box::pin(iter([1usize].into_iter())) as UsizeStream);
+
+    let mut buffer = vec![];
+    let n = poll_fn(|cx| stream_map.poll_next_many(cx, &mut buffer, 2)).await;
+
+    assert_eq!(n, 2);
+    assert_eq!(buffer.len(), 2);
+    assert!(buffer.contains(&(0, 0)));
+    assert!(buffer.contains(&(1, 1)));
+}
+
+#[tokio::test]
+async fn poll_next_many_correctly_loops_around() {
+    for _ in 0..10 {
+        let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+        stream_map.insert(0, Box::pin(iter([0usize].into_iter())) as UsizeStream);
+        stream_map.insert(1, Box::pin(iter([0usize, 1].into_iter())) as UsizeStream);
+        stream_map.insert(2, Box::pin(iter([0usize, 1, 2].into_iter())) as UsizeStream);
+
+        let mut buffer = vec![];
+
+        let n = poll_fn(|cx| stream_map.poll_next_many(cx, &mut buffer, 3)).await;
+        assert_eq!(n, 3);
+        assert_eq!(
+            std::mem::take(&mut buffer)
+                .into_iter()
+                .map(|(_, v)| v)
+                .collect::<Vec<_>>(),
+            vec![0, 0, 0]
+        );
+
+        let n = poll_fn(|cx| stream_map.poll_next_many(cx, &mut buffer, 2)).await;
+        assert_eq!(n, 2);
+        assert_eq!(
+            std::mem::take(&mut buffer)
+                .into_iter()
+                .map(|(_, v)| v)
+                .collect::<Vec<_>>(),
+            vec![1, 1]
+        );
+
+        let n = poll_fn(|cx| stream_map.poll_next_many(cx, &mut buffer, 1)).await;
+        assert_eq!(n, 1);
+        assert_eq!(
+            std::mem::take(&mut buffer)
+                .into_iter()
+                .map(|(_, v)| v)
+                .collect::<Vec<_>>(),
+            vec![2]
+        );
+    }
+}
+
+#[tokio::test]
+async fn next_many_zero() {
+    let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+    stream_map.insert(0, Box::pin(pending()) as UsizeStream);
+
+    let n = poll_fn(|cx| pin!(stream_map.next_many(&mut vec![], 0)).poll(cx)).await;
+
+    assert_eq!(n, 0);
+}
+
+#[tokio::test]
+async fn next_many_empty() {
+    let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+    let n = stream_map.next_many(&mut vec![], 1).await;
+
+    assert_eq!(n, 0);
+}
+
+#[tokio::test]
+async fn next_many_pending() {
+    let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+    stream_map.insert(0, Box::pin(pending()) as UsizeStream);
+
+    let mut is_pending = false;
+    poll_fn(|cx| {
+        let poll = pin!(stream_map.next_many(&mut vec![], 1)).poll(cx);
+
+        is_pending = poll.is_pending();
+
+        Poll::Ready(())
+    })
+    .await;
+
+    assert!(is_pending);
+}
+
+#[tokio::test]
+async fn next_many_not_enough() {
+    let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+    stream_map.insert(0, Box::pin(iter([0usize].into_iter())) as UsizeStream);
+    stream_map.insert(1, Box::pin(iter([1usize].into_iter())) as UsizeStream);
+
+    let mut buffer = vec![];
+    let n = poll_fn(|cx| pin!(stream_map.next_many(&mut buffer, 3)).poll(cx)).await;
+
+    assert_eq!(n, 2);
+    assert_eq!(buffer.len(), 2);
+    assert!(buffer.contains(&(0, 0)));
+    assert!(buffer.contains(&(1, 1)));
+}
+
+#[tokio::test]
+async fn next_many_enough() {
+    let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+    stream_map.insert(0, Box::pin(iter([0usize].into_iter())) as UsizeStream);
+    stream_map.insert(1, Box::pin(iter([1usize].into_iter())) as UsizeStream);
+
+    let mut buffer = vec![];
+    let n = poll_fn(|cx| pin!(stream_map.next_many(&mut buffer, 2)).poll(cx)).await;
+
+    assert_eq!(n, 2);
+    assert_eq!(buffer.len(), 2);
+    assert!(buffer.contains(&(0, 0)));
+    assert!(buffer.contains(&(1, 1)));
+}
+
+#[tokio::test]
+async fn next_many_correctly_loops_around() {
+    for _ in 0..10 {
+        let mut stream_map: StreamMap<usize, UsizeStream> = StreamMap::new();
+
+        stream_map.insert(0, Box::pin(iter([0usize].into_iter())) as UsizeStream);
+        stream_map.insert(1, Box::pin(iter([0usize, 1].into_iter())) as UsizeStream);
+        stream_map.insert(2, Box::pin(iter([0usize, 1, 2].into_iter())) as UsizeStream);
+
+        let mut buffer = vec![];
+
+        let n = poll_fn(|cx| pin!(stream_map.next_many(&mut buffer, 3)).poll(cx)).await;
+        assert_eq!(n, 3);
+        assert_eq!(
+            std::mem::take(&mut buffer)
+                .into_iter()
+                .map(|(_, v)| v)
+                .collect::<Vec<_>>(),
+            vec![0, 0, 0]
+        );
+
+        let n = poll_fn(|cx| pin!(stream_map.next_many(&mut buffer, 2)).poll(cx)).await;
+        assert_eq!(n, 2);
+        assert_eq!(
+            std::mem::take(&mut buffer)
+                .into_iter()
+                .map(|(_, v)| v)
+                .collect::<Vec<_>>(),
+            vec![1, 1]
+        );
+
+        let n = poll_fn(|cx| pin!(stream_map.next_many(&mut buffer, 1)).poll(cx)).await;
+        assert_eq!(n, 1);
+        assert_eq!(
+            std::mem::take(&mut buffer)
+                .into_iter()
+                .map(|(_, v)| v)
+                .collect::<Vec<_>>(),
+            vec![2]
+        );
+    }
+}

tokio-test/CHANGELOG.md

@@ -1,3 +1,27 @@
+# 0.4.4 (March 14, 2024)
+
+- task: mark `Spawn` as `#[must_use]` ([#6371])
+- test: increase MSRV to 1.63 ([#6126])
+- test: update category slug ([#5953])
+
+[#5953]: https://github.com/tokio-rs/tokio/pull/5953
+[#6126]: https://github.com/tokio-rs/tokio/pull/6126
+[#6371]: https://github.com/tokio-rs/tokio/pull/6371
+
+# 0.4.3 (August 23, 2023)
+
+- deps: fix minimum required version of `async-stream` ([#5347])
+- deps: fix minimum required version of `tokio-stream` ([#4376])
+- docs: improve `tokio_test::task` docs ([#5132])
+- io: fetch actions from mock handle before write ([#5814])
+- io: fix wait operation on mock ([#5554])
+
+[#4376]: https://github.com/tokio-rs/tokio/pull/4376
+[#5132]: https://github.com/tokio-rs/tokio/pull/5132
+[#5347]: https://github.com/tokio-rs/tokio/pull/5347
+[#5554]: https://github.com/tokio-rs/tokio/pull/5554
+[#5814]: https://github.com/tokio-rs/tokio/pull/5814
+
 # 0.4.2 (May 14, 2021)
 
 - test: add `assert_elapsed!` macro ([#3728])

tokio-test/Cargo.toml

@@ -4,9 +4,9 @@ name = "tokio-test"
 # - Remove path dependencies
 # - Update CHANGELOG.md.
 # - Create "tokio-test-0.4.x" git tag.
-version = "0.4.2"
+version = "0.4.4"
 edition = "2021"
-rust-version = "1.56"
+rust-version = "1.63"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
@@ -14,7 +14,7 @@ homepage = "https://tokio.rs"
 description = """
 Testing utilities for Tokio- and futures-based code
 """
-categories = ["asynchronous", "testing"]
+categories = ["asynchronous", "development-tools::testing"]
 
 [dependencies]
 tokio = { version = "1.2.0", path = "../tokio", features = ["rt", "sync", "time", "test-util"] }

tokio-test/src/io.rs

@@ -74,7 +74,7 @@ struct Inner {
 }
 
 impl Builder {
-    /// Return a new, empty `Builder.
+    /// Return a new, empty `Builder`.
     pub fn new() -> Self {
         Self::default()
     }
@@ -409,6 +409,20 @@ impl AsyncWrite for Mock {
             // If a sleep is set, it has already fired
             self.inner.sleep = None;
 
+            if self.inner.actions.is_empty() {
+                match self.inner.poll_action(cx) {
+                    Poll::Pending => {
+                        // do not propagate pending
+                    }
+                    Poll::Ready(Some(action)) => {
+                        self.inner.actions.push_back(action);
+                    }
+                    Poll::Ready(None) => {
+                        panic!("unexpected write");
+                    }
+                }
+            }
+
             match self.inner.write(buf) {
                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
                     if let Some(rem) = self.inner.remaining_wait() {
@@ -464,7 +478,7 @@ impl Drop for Mock {
             Action::Read(data) => assert!(data.is_empty(), "There is still data left to read."),
             Action::Write(data) => assert!(data.is_empty(), "There is still data left to write."),
             _ => (),
-        })
+        });
     }
 }
 /*

tokio-test/src/lib.rs

@@ -12,6 +12,7 @@
 //! Tokio and Futures based testing utilities
 
 pub mod io;
+pub mod stream_mock;
 
 mod macros;
 pub mod task;

tokio-test/src/macros.rs

@@ -22,17 +22,17 @@
 #[macro_export]
 macro_rules! assert_ready {
     ($e:expr) => {{
-        use core::task::Poll::*;
+        use core::task::Poll;
         match $e {
-            Ready(v) => v,
-            Pending => panic!("pending"),
+            Poll::Ready(v) => v,
+            Poll::Pending => panic!("pending"),
         }
     }};
     ($e:expr, $($msg:tt)+) => {{
-        use core::task::Poll::*;
+        use core::task::Poll;
         match $e {
-            Ready(v) => v,
-            Pending => {
+            Poll::Ready(v) => v,
+            Poll::Pending => {
                 panic!("pending; {}", format_args!($($msg)+))
             }
         }
@@ -127,17 +127,17 @@ macro_rules! assert_ready_err {
 #[macro_export]
 macro_rules! assert_pending {
     ($e:expr) => {{
-        use core::task::Poll::*;
+        use core::task::Poll;
         match $e {
-            Pending => {}
-            Ready(v) => panic!("ready; value = {:?}", v),
+            Poll::Pending => {}
+            Poll::Ready(v) => panic!("ready; value = {:?}", v),
         }
     }};
     ($e:expr, $($msg:tt)+) => {{
-        use core::task::Poll::*;
+        use core::task::Poll;
         match $e {
-            Pending => {}
-            Ready(v) => {
+            Poll::Pending => {}
+            Poll::Ready(v) => {
                 panic!("ready; value = {:?}; {}", v, format_args!($($msg)+))
             }
         }

tokio-test/src/stream_mock.rs

@@ -0,0 +1,168 @@
+#![cfg(not(loom))]
+
+//! A mock stream implementing [`Stream`].
+//!
+//! # Overview
+//! This crate provides a `StreamMock` that can be used to test code that interacts with streams.
+//! It allows you to mock the behavior of a stream and control the items it yields and the waiting
+//! intervals between items.
+//!
+//! # Usage
+//! To use the `StreamMock`, you need to create a builder using [`StreamMockBuilder`]. The builder
+//! allows you to enqueue actions such as returning items or waiting for a certain duration.
+//!
+//! # Example
+//! ```rust
+//!
+//! use futures_util::StreamExt;
+//! use std::time::Duration;
+//! use tokio_test::stream_mock::StreamMockBuilder;
+//!
+//! async fn test_stream_mock_wait() {
+//!     let mut stream_mock = StreamMockBuilder::new()
+//!         .next(1)
+//!         .wait(Duration::from_millis(300))
+//!         .next(2)
+//!         .build();
+//!
+//!     assert_eq!(stream_mock.next().await, Some(1));
+//!     let start = std::time::Instant::now();
+//!     assert_eq!(stream_mock.next().await, Some(2));
+//!     let elapsed = start.elapsed();
+//!     assert!(elapsed >= Duration::from_millis(300));
+//!     assert_eq!(stream_mock.next().await, None);
+//! }
+//! ```
+
+use std::collections::VecDeque;
+use std::pin::Pin;
+use std::task::Poll;
+use std::time::Duration;
+
+use futures_core::{ready, Stream};
+use std::future::Future;
+use tokio::time::{sleep_until, Instant, Sleep};
+
+#[derive(Debug, Clone)]
+enum Action<T: Unpin> {
+    Next(T),
+    Wait(Duration),
+}
+
+/// A builder for [`StreamMock`]
+#[derive(Debug, Clone)]
+pub struct StreamMockBuilder<T: Unpin> {
+    actions: VecDeque<Action<T>>,
+}
+
+impl<T: Unpin> StreamMockBuilder<T> {
+    /// Create a new empty [`StreamMockBuilder`]
+    pub fn new() -> Self {
+        StreamMockBuilder::default()
+    }
+
+    /// Queue an item to be returned by the stream
+    pub fn next(mut self, value: T) -> Self {
+        self.actions.push_back(Action::Next(value));
+        self
+    }
+
+    // Queue an item to be consumed by the sink,
+    // commented out until Sink is implemented.
+    //
+    // pub fn consume(mut self, value: T) -> Self {
+    //    self.actions.push_back(Action::Consume(value));
+    //    self
+    // }
+
+    /// Queue the stream to wait for a duration
+    pub fn wait(mut self, duration: Duration) -> Self {
+        self.actions.push_back(Action::Wait(duration));
+        self
+    }
+
+    /// Build the [`StreamMock`]
+    pub fn build(self) -> StreamMock<T> {
+        StreamMock {
+            actions: self.actions,
+            sleep: None,
+        }
+    }
+}
+
+impl<T: Unpin> Default for StreamMockBuilder<T> {
+    fn default() -> Self {
+        StreamMockBuilder {
+            actions: VecDeque::new(),
+        }
+    }
+}
+
+/// A mock stream implementing [`Stream`]
+///
+/// See [`StreamMockBuilder`] for more information.
+#[derive(Debug)]
+pub struct StreamMock<T: Unpin> {
+    actions: VecDeque<Action<T>>,
+    sleep: Option<Pin<Box<Sleep>>>,
+}
+
+impl<T: Unpin> StreamMock<T> {
+    fn next_action(&mut self) -> Option<Action<T>> {
+        self.actions.pop_front()
+    }
+}
+
+impl<T: Unpin> Stream for StreamMock<T> {
+    type Item = T;
+
+    fn poll_next(
+        mut self: std::pin::Pin<&mut Self>,
+        cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Option<Self::Item>> {
+        // Try polling the sleep future first
+        if let Some(ref mut sleep) = self.sleep {
+            ready!(Pin::new(sleep).poll(cx));
+            // Since we're ready, discard the sleep future
+            self.sleep.take();
+        }
+
+        match self.next_action() {
+            Some(action) => match action {
+                Action::Next(item) => Poll::Ready(Some(item)),
+                Action::Wait(duration) => {
+                    // Set up a sleep future and schedule this future to be polled again for it.
+                    self.sleep = Some(Box::pin(sleep_until(Instant::now() + duration)));
+                    cx.waker().wake_by_ref();
+
+                    Poll::Pending
+                }
+            },
+            None => Poll::Ready(None),
+        }
+    }
+}
+
+impl<T: Unpin> Drop for StreamMock<T> {
+    fn drop(&mut self) {
+        // Avoid double panicking to make debugging easier.
+        if std::thread::panicking() {
+            return;
+        }
+
+        let undropped_count = self
+            .actions
+            .iter()
+            .filter(|action| match action {
+                Action::Next(_) => true,
+                Action::Wait(_) => false,
+            })
+            .count();
+
+        assert!(
+            undropped_count == 0,
+            "StreamMock was dropped before all actions were consumed, {} actions were not consumed",
+            undropped_count
+        );
+    }
+}

tokio-test/src/task.rs

@@ -25,8 +25,6 @@
 //! assert!(task.poll().is_ready(), "Task was not ready!");
 //! ```
 
-#![allow(clippy::mutex_atomic)]
-
 use std::future::Future;
 use std::mem;
 use std::ops;
@@ -51,6 +49,7 @@ pub fn spawn<T>(task: T) -> Spawn<T> {
 /// Future spawned on a mock task that can be used to poll the future or stream
 /// without needing pinning or context types.
 #[derive(Debug)]
+#[must_use = "futures do nothing unless you `.await` or poll them"]
 pub struct Spawn<T> {
     task: MockTask,
     future: Pin<Box<T>>,
@@ -127,7 +126,7 @@ impl<T: Future> Spawn<T> {
 }
 
 impl<T: Stream> Spawn<T> {
-    /// If `T` is a [`Stream`] then poll_next it. This will handle pinning and the context
+    /// If `T` is a [`Stream`] then `poll_next` it. This will handle pinning and the context
     /// type for the stream.
     pub fn poll_next(&mut self) -> Poll<Option<T::Item>> {
         let stream = self.future.as_mut();

tokio-test/tests/io.rs

@@ -51,6 +51,29 @@ async fn write() {
     mock.write_all(b"world!").await.expect("write 2");
 }
 
+#[tokio::test]
+async fn write_with_handle() {
+    let (mut mock, mut handle) = Builder::new().build_with_handle();
+    handle.write(b"hello ");
+    handle.write(b"world!");
+
+    mock.write_all(b"hello ").await.expect("write 1");
+    mock.write_all(b"world!").await.expect("write 2");
+}
+
+#[tokio::test]
+async fn read_with_handle() {
+    let (mut mock, mut handle) = Builder::new().build_with_handle();
+    handle.read(b"hello ");
+    handle.read(b"world!");
+
+    let mut buf = vec![0; 6];
+    mock.read_exact(&mut buf).await.expect("read 1");
+    assert_eq!(&buf[..], b"hello ");
+    mock.read_exact(&mut buf).await.expect("read 2");
+    assert_eq!(&buf[..], b"world!");
+}
+
 #[tokio::test]
 async fn write_error() {
     let error = io::Error::new(io::ErrorKind::Other, "cruel");

tokio-test/tests/stream_mock.rs

@@ -0,0 +1,50 @@
+use futures_util::StreamExt;
+use std::time::Duration;
+use tokio_test::stream_mock::StreamMockBuilder;
+
+#[tokio::test]
+async fn test_stream_mock_empty() {
+    let mut stream_mock = StreamMockBuilder::<u32>::new().build();
+
+    assert_eq!(stream_mock.next().await, None);
+    assert_eq!(stream_mock.next().await, None);
+}
+
+#[tokio::test]
+async fn test_stream_mock_items() {
+    let mut stream_mock = StreamMockBuilder::new().next(1).next(2).build();
+
+    assert_eq!(stream_mock.next().await, Some(1));
+    assert_eq!(stream_mock.next().await, Some(2));
+    assert_eq!(stream_mock.next().await, None);
+}
+
+#[tokio::test]
+async fn test_stream_mock_wait() {
+    let mut stream_mock = StreamMockBuilder::new()
+        .next(1)
+        .wait(Duration::from_millis(300))
+        .next(2)
+        .build();
+
+    assert_eq!(stream_mock.next().await, Some(1));
+    let start = std::time::Instant::now();
+    assert_eq!(stream_mock.next().await, Some(2));
+    let elapsed = start.elapsed();
+    assert!(elapsed >= Duration::from_millis(300));
+    assert_eq!(stream_mock.next().await, None);
+}
+
+#[tokio::test]
+#[should_panic(expected = "StreamMock was dropped before all actions were consumed")]
+async fn test_stream_mock_drop_without_consuming_all() {
+    let stream_mock = StreamMockBuilder::new().next(1).next(2).build();
+    drop(stream_mock);
+}
+
+#[tokio::test]
+#[should_panic(expected = "test panic was not masked")]
+async fn test_stream_mock_drop_during_panic_doesnt_mask_panic() {
+    let _stream_mock = StreamMockBuilder::new().next(1).next(2).build();
+    panic!("test panic was not masked");
+}

tokio-util/CHANGELOG.md

@@ -1,3 +1,48 @@
+# 0.7.10 (October 24th, 2023)
+
+### Added
+
+- task: add `TaskTracker` ([#6033])
+- task: add `JoinMap::keys` ([#6046])
+- io: implement `Seek` for `SyncIoBridge` ([#6058])
+
+### Changed
+
+- deps: update hashbrown to 0.14 ([#6102])
+
+[#6033]: https://github.com/tokio-rs/tokio/pull/6033
+[#6046]: https://github.com/tokio-rs/tokio/pull/6046
+[#6058]: https://github.com/tokio-rs/tokio/pull/6058
+[#6102]: https://github.com/tokio-rs/tokio/pull/6102
+
+# 0.7.9 (September 20th, 2023)
+
+### Added
+
+- io: add passthrough `AsyncRead`/`AsyncWrite` to `InspectWriter`/`InspectReader` ([#5739])
+- task: add spawn blocking methods to `JoinMap` ([#5797])
+- io: pass through traits for `StreamReader` and `SinkWriter` ([#5941])
+- io: add `SyncIoBridge::into_inner` ([#5971])
+
+### Fixed
+
+- sync: handle possibly dangling reference safely ([#5812])
+- util: fix broken intra-doc link ([#5849])
+- compat: fix clippy warnings ([#5891])
+
+### Documented
+
+- codec: Specify the line ending of `LinesCodec` ([#5982])
+
+[#5739]: https://github.com/tokio-rs/tokio/pull/5739
+[#5797]: https://github.com/tokio-rs/tokio/pull/5797
+[#5941]: https://github.com/tokio-rs/tokio/pull/5941
+[#5971]: https://github.com/tokio-rs/tokio/pull/5971
+[#5812]: https://github.com/tokio-rs/tokio/pull/5812
+[#5849]: https://github.com/tokio-rs/tokio/pull/5849
+[#5891]: https://github.com/tokio-rs/tokio/pull/5891
+[#5982]: https://github.com/tokio-rs/tokio/pull/5982
+
 # 0.7.8 (April 25th, 2023)
 
 This release bumps the MSRV of tokio-util to 1.56.

tokio-util/Cargo.toml

@@ -4,9 +4,9 @@ name = "tokio-util"
 # - Remove path dependencies
 # - Update CHANGELOG.md.
 # - Create "tokio-util-0.7.x" git tag.
-version = "0.7.8"
+version = "0.7.10"
 edition = "2021"
-rust-version = "1.56"
+rust-version = "1.63"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
@@ -34,18 +34,18 @@ rt = ["tokio/rt", "tokio/sync", "futures-util", "hashbrown"]
 __docs_rs = ["futures-util"]
 
 [dependencies]
-tokio = { version = "1.22.0", path = "../tokio", features = ["sync"] }
+tokio = { version = "1.28.0", path = "../tokio", features = ["sync"] }
 bytes = "1.0.0"
 futures-core = "0.3.0"
 futures-sink = "0.3.0"
 futures-io = { version = "0.3.0", optional = true }
 futures-util = { version = "0.3.0", optional = true }
-pin-project-lite = "0.2.0"
+pin-project-lite = "0.2.11"
 slab = { version = "0.4.4", optional = true } # Backs `DelayQueue`
 tracing = { version = "0.1.25", default-features = false, features = ["std"], optional = true }
 
 [target.'cfg(tokio_unstable)'.dependencies]
-hashbrown = { version = "0.12.0", optional = true }
+hashbrown = { version = "0.14.0", optional = true }
 
 [dev-dependencies]
 tokio = { version = "1.0.0", path = "../tokio", features = ["full"] }
@@ -56,6 +56,7 @@ async-stream = "0.3.0"
 futures = "0.3.0"
 futures-test = "0.3.5"
 parking_lot = "0.12.0"
+tempfile = "3.1.0"
 
 [package.metadata.docs.rs]
 all-features = true

tokio-util/src/codec/framed.rs

@@ -20,10 +20,21 @@ pin_project! {
     /// You can create a `Framed` instance by using the [`Decoder::framed`] adapter, or
     /// by using the `new` function seen below.
     ///
+    /// # Cancellation safety
+    ///
+    /// * [`futures_util::sink::SinkExt::send`]: if send is used as the event in a
+    /// `tokio::select!` statement and some other branch completes first, then it is
+    /// guaranteed that the message was not sent, but the message itself is lost.
+    /// * [`tokio_stream::StreamExt::next`]: This method is cancel safe. The returned
+    /// future only holds onto a reference to the underlying stream, so dropping it will
+    /// never lose a value.
+    ///
     /// [`Stream`]: futures_core::Stream
     /// [`Sink`]: futures_sink::Sink
     /// [`AsyncRead`]: tokio::io::AsyncRead
     /// [`Decoder::framed`]: crate::codec::Decoder::framed()
+    /// [`futures_util::sink::SinkExt::send`]: futures_util::sink::SinkExt::send
+    /// [`tokio_stream::StreamExt::next`]: https://docs.rs/tokio-stream/latest/tokio_stream/trait.StreamExt.html#method.next
     pub struct Framed<T, U> {
         #[pin]
         inner: FramedImpl<T, U, RWFrames>
@@ -130,7 +141,7 @@ impl<T, U> Framed<T, U> {
     /// things like gzip or TLS, which require both read and write access to the
     /// underlying object.
     ///
-    /// This objects takes a stream and a readbuffer and a writebuffer. These field
+    /// This objects takes a stream and a `readbuffer` and a `writebuffer`. These field
     /// can be obtained from an existing `Framed` with the [`into_parts`] method.
     ///
     /// If you want to work more directly with the streams and sink, consider

tokio-util/src/codec/framed_impl.rs

@@ -218,6 +218,7 @@ where
             // Make sure we've got room for at least one byte to read to ensure
             // that we don't get a spurious 0 that looks like EOF.
             state.buffer.reserve(1);
+            #[allow(clippy::blocks_in_conditions)]
             let bytect = match poll_read_buf(pinned.inner.as_mut(), cx, &mut state.buffer).map_err(
                 |err| {
                     trace!("Got an error, going to errored state");

tokio-util/src/codec/framed_read.rs

@@ -14,8 +14,18 @@ use std::task::{Context, Poll};
 pin_project! {
     /// A [`Stream`] of messages decoded from an [`AsyncRead`].
     ///
+    /// For examples of how to use `FramedRead` with a codec, see the
+    /// examples on the [`codec`] module.
+    ///
+    /// # Cancellation safety
+    /// * [`tokio_stream::StreamExt::next`]: This method is cancel safe. The returned
+    /// future only holds onto a reference to the underlying stream, so dropping it will
+    /// never lose a value.
+    ///
     /// [`Stream`]: futures_core::Stream
     /// [`AsyncRead`]: tokio::io::AsyncRead
+    /// [`codec`]: crate::codec
+    /// [`tokio_stream::StreamExt::next`]: https://docs.rs/tokio-stream/latest/tokio_stream/trait.StreamExt.html#method.next
     pub struct FramedRead<T, D> {
         #[pin]
         inner: FramedImpl<T, D, ReadFrame>,

tokio-util/src/codec/framed_write.rs

@@ -15,7 +15,18 @@ use std::task::{Context, Poll};
 pin_project! {
     /// A [`Sink`] of frames encoded to an `AsyncWrite`.
     ///
+    /// For examples of how to use `FramedWrite` with a codec, see the
+    /// examples on the [`codec`] module.
+    ///
+    /// # Cancellation safety
+    ///
+    /// * [`futures_util::sink::SinkExt::send`]: if send is used as the event in a
+    /// `tokio::select!` statement and some other branch completes first, then it is
+    /// guaranteed that the message was not sent, but the message itself is lost.
+    ///
     /// [`Sink`]: futures_sink::Sink
+    /// [`codec`]: crate::codec
+    /// [`futures_util::sink::SinkExt::send`]: futures_util::sink::SinkExt::send
     pub struct FramedWrite<T, E> {
         #[pin]
         inner: FramedImpl<T, E, WriteFrame>,

tokio-util/src/codec/length_delimited.rs

@@ -386,6 +386,10 @@ use std::{cmp, fmt, mem};
 /// `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.
+///
+/// Note that the if the value of [`Builder::max_frame_length`] becomes larger than
+/// what can actually fit in [`Builder::length_field_length`], it will be clipped to
+/// the maximum value that can fit.
 #[derive(Debug, Clone, Copy)]
 pub struct Builder {
     // Maximum frame length
@@ -935,8 +939,12 @@ impl Builder {
     /// # }
     /// ```
     pub fn new_codec(&self) -> LengthDelimitedCodec {
+        let mut builder = *self;
+
+        builder.adjust_max_frame_len();
+
         LengthDelimitedCodec {
-            builder: *self,
+            builder,
             state: DecodeState::Head,
         }
     }
@@ -1018,6 +1026,35 @@ impl Builder {
         self.num_skip
             .unwrap_or(self.length_field_offset + self.length_field_len)
     }
+
+    fn adjust_max_frame_len(&mut self) {
+        // This function is basically `std::u64::saturating_add_signed`. Since it
+        // requires MSRV 1.66, its implementation is copied here.
+        //
+        // TODO: use the method from std when MSRV becomes >= 1.66
+        fn saturating_add_signed(num: u64, rhs: i64) -> u64 {
+            let (res, overflow) = num.overflowing_add(rhs as u64);
+            if overflow == (rhs < 0) {
+                res
+            } else if overflow {
+                u64::MAX
+            } else {
+                0
+            }
+        }
+
+        // Calculate the maximum number that can be represented using `length_field_len` bytes.
+        let max_number = match 1u64.checked_shl((8 * self.length_field_len) as u32) {
+            Some(shl) => shl - 1,
+            None => u64::MAX,
+        };
+
+        let max_allowed_len = saturating_add_signed(max_number, self.length_adjustment as i64);
+
+        if self.max_frame_len as u64 > max_allowed_len {
+            self.max_frame_len = usize::try_from(max_allowed_len).unwrap_or(usize::MAX);
+        }
+    }
 }
 
 impl Default for Builder {

tokio-util/src/codec/lines_codec.rs

@@ -6,6 +6,8 @@ use std::{cmp, fmt, io, str, usize};
 
 /// A simple [`Decoder`] and [`Encoder`] implementation that splits up data into lines.
 ///
+/// This uses the `\n` character as the line ending on all platforms.
+///
 /// [`Decoder`]: crate::codec::Decoder
 /// [`Encoder`]: crate::codec::Encoder
 #[derive(Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]

tokio-util/src/codec/mod.rs

@@ -1,4 +1,4 @@
-//! Adaptors from AsyncRead/AsyncWrite to Stream/Sink
+//! Adaptors from `AsyncRead`/`AsyncWrite` to Stream/Sink
 //!
 //! Raw I/O objects work with byte sequences, but higher-level code usually
 //! wants to batch these into meaningful chunks, called "frames".
@@ -7,6 +7,71 @@
 //! [`AsyncWrite`], to framed streams implementing [`Sink`] and [`Stream`].
 //! Framed streams are also known as transports.
 //!
+//! # Example encoding using `LinesCodec`
+//!
+//! The following example demonstrates how to use a codec such as [`LinesCodec`] to
+//! write framed data. [`FramedWrite`] can be used to achieve this. Data sent to
+//! [`FramedWrite`] are first framed according to a specific codec, and then sent to
+//! an implementor of [`AsyncWrite`].
+//!
+//! ```
+//! use futures::sink::SinkExt;
+//! use tokio_util::codec::LinesCodec;
+//! use tokio_util::codec::FramedWrite;
+//!
+//! #[tokio::main]
+//! async fn main() {
+//!     let buffer = Vec::new();
+//!     let messages = vec!["Hello", "World"];
+//!     let encoder = LinesCodec::new();
+//!
+//!     // FramedWrite is a sink which means you can send values into it
+//!     // asynchronously.
+//!     let mut writer = FramedWrite::new(buffer, encoder);
+//!
+//!     // To be able to send values into a FramedWrite, you need to bring the
+//!     // `SinkExt` trait into scope.
+//!     writer.send(messages[0]).await.unwrap();
+//!     writer.send(messages[1]).await.unwrap();
+//!
+//!     let buffer = writer.get_ref();
+//!
+//!     assert_eq!(buffer.as_slice(), "Hello\nWorld\n".as_bytes());
+//! }
+//!```
+//!
+//! # Example decoding using `LinesCodec`
+//! The following example demonstrates how to use a codec such as [`LinesCodec`] to
+//! read a stream of framed data. [`FramedRead`] can be used to achieve this. [`FramedRead`]
+//! will keep reading from an [`AsyncRead`] implementor until a whole frame, according to a codec,
+//! can be parsed.
+//!
+//!```
+//! use tokio_stream::StreamExt;
+//! use tokio_util::codec::LinesCodec;
+//! use tokio_util::codec::FramedRead;
+//!
+//! #[tokio::main]
+//! async fn main() {
+//!     let message = "Hello\nWorld".as_bytes();
+//!     let decoder = LinesCodec::new();
+//!
+//!     // FramedRead can be used to read a stream of values that are framed according to
+//!     // a codec. FramedRead will read from its input (here `buffer`) until a whole frame
+//!     // can be parsed.
+//!     let mut reader = FramedRead::new(message, decoder);
+//!
+//!     // To read values from a FramedRead, you need to bring the
+//!     // `StreamExt` trait into scope.
+//!     let frame1 = reader.next().await.unwrap().unwrap();
+//!     let frame2 = reader.next().await.unwrap().unwrap();
+//!
+//!     assert!(reader.next().await.is_none());
+//!     assert_eq!(frame1, "Hello");
+//!     assert_eq!(frame2, "World");
+//! }
+//! ```
+//!
 //! # The Decoder trait
 //!
 //! A [`Decoder`] is used together with [`FramedRead`] or [`Framed`] to turn an
@@ -248,6 +313,7 @@
 //! [`AsyncWrite`]: tokio::io::AsyncWrite
 //! [`Stream`]: futures_core::Stream
 //! [`Sink`]: futures_sink::Sink
+//! [`SinkExt`]: futures::sink::SinkExt
 //! [`SinkExt::close`]: https://docs.rs/futures/0.3/futures/sink/trait.SinkExt.html#method.close
 //! [`FramedRead`]: struct@crate::codec::FramedRead
 //! [`FramedWrite`]: struct@crate::codec::FramedWrite

tokio-util/src/compat.rs

@@ -227,12 +227,14 @@ impl<T: tokio::io::AsyncSeek> futures_io::AsyncSeek for Compat<T> {
         pos: io::SeekFrom,
     ) -> Poll<io::Result<u64>> {
         if self.seek_pos != Some(pos) {
+            // Ensure previous seeks have finished before starting a new one
+            ready!(self.as_mut().project().inner.poll_complete(cx))?;
             self.as_mut().project().inner.start_seek(pos)?;
             *self.as_mut().project().seek_pos = Some(pos);
         }
         let res = ready!(self.as_mut().project().inner.poll_complete(cx));
         *self.as_mut().project().seek_pos = None;
-        Poll::Ready(res.map(|p| p as u64))
+        Poll::Ready(res)
     }
 }
 
@@ -255,7 +257,7 @@ impl<T: futures_io::AsyncSeek> tokio::io::AsyncSeek for Compat<T> {
         };
         let res = ready!(self.as_mut().project().inner.poll_seek(cx, pos));
         *self.as_mut().project().seek_pos = None;
-        Poll::Ready(res.map(|p| p as u64))
+        Poll::Ready(res)
     }
 }
 

tokio-util/src/either.rs

@@ -116,7 +116,7 @@ where
     }
 
     fn consume(self: Pin<&mut Self>, amt: usize) {
-        delegate_call!(self.consume(amt))
+        delegate_call!(self.consume(amt));
     }
 }
 
@@ -164,6 +164,39 @@ where
     }
 }
 
+impl<L, R, Item, Error> futures_sink::Sink<Item> for Either<L, R>
+where
+    L: futures_sink::Sink<Item, Error = Error>,
+    R: futures_sink::Sink<Item, Error = Error>,
+{
+    type Error = Error;
+
+    fn poll_ready(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<std::result::Result<(), Self::Error>> {
+        delegate_call!(self.poll_ready(cx))
+    }
+
+    fn start_send(self: Pin<&mut Self>, item: Item) -> std::result::Result<(), Self::Error> {
+        delegate_call!(self.start_send(item))
+    }
+
+    fn poll_flush(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<std::result::Result<(), Self::Error>> {
+        delegate_call!(self.poll_flush(cx))
+    }
+
+    fn poll_close(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<std::result::Result<(), Self::Error>> {
+        delegate_call!(self.poll_close(cx))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

tokio-util/src/io/copy_to_bytes.rs

@@ -1,4 +1,5 @@
 use bytes::Bytes;
+use futures_core::stream::Stream;
 use futures_sink::Sink;
 use pin_project_lite::pin_project;
 use std::pin::Pin;
@@ -66,3 +67,10 @@ where
         self.project().inner.poll_close(cx)
     }
 }
+
+impl<S: Stream> Stream for CopyToBytes<S> {
+    type Item = S::Item;
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        self.project().inner.poll_next(cx)
+    }
+}

tokio-util/src/io/inspect.rs

@@ -18,7 +18,7 @@ pin_project! {
 }
 
 impl<R, F> InspectReader<R, F> {
-    /// Create a new InspectReader, wrapping `reader` and calling `f` for the
+    /// Create a new `InspectReader`, wrapping `reader` and calling `f` for the
     /// new data supplied by each read call.
     ///
     /// The closure will only be called with an empty slice if the inner reader
@@ -100,7 +100,7 @@ pin_project! {
 }
 
 impl<W, F> InspectWriter<W, F> {
-    /// Create a new InspectWriter, wrapping `write` and calling `f` for the
+    /// Create a new `InspectWriter`, wrapping `write` and calling `f` for the
     /// data successfully written by each write call.
     ///
     /// The closure `f` will never be called with an empty slice. A vectored

tokio-util/src/io/sink_writer.rs

@@ -1,11 +1,12 @@
 use futures_core::ready;
 use futures_sink::Sink;
 
+use futures_core::stream::Stream;
 use pin_project_lite::pin_project;
 use std::io;
 use std::pin::Pin;
 use std::task::{Context, Poll};
-use tokio::io::AsyncWrite;
+use tokio::io::{AsyncRead, AsyncWrite};
 
 pin_project! {
     /// Convert a [`Sink`] of byte chunks into an [`AsyncWrite`].
@@ -59,7 +60,7 @@ pin_project! {
     /// [`CopyToBytes`]: crate::io::CopyToBytes
     /// [`Encoder`]: crate::codec::Encoder
     /// [`Sink`]: futures_sink::Sink
-    /// [`codec`]: tokio_util::codec
+    /// [`codec`]: crate::codec
     #[derive(Debug)]
     pub struct SinkWriter<S> {
         #[pin]
@@ -115,3 +116,20 @@ where
         self.project().inner.poll_close(cx).map_err(Into::into)
     }
 }
+
+impl<S: Stream> Stream for SinkWriter<S> {
+    type Item = S::Item;
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        self.project().inner.poll_next(cx)
+    }
+}
+
+impl<S: AsyncRead> AsyncRead for SinkWriter<S> {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut tokio::io::ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        self.project().inner.poll_read(cx, buf)
+    }
+}

tokio-util/src/io/stream_reader.rs

@@ -1,5 +1,6 @@
 use bytes::Buf;
 use futures_core::stream::Stream;
+use futures_sink::Sink;
 use std::io;
 use std::pin::Pin;
 use std::task::{Context, Poll};
@@ -165,7 +166,7 @@ where
     B: Buf,
     E: Into<std::io::Error>,
 {
-    /// Convert a stream of byte chunks into an [`AsyncRead`](tokio::io::AsyncRead).
+    /// Convert a stream of byte chunks into an [`AsyncRead`].
     ///
     /// The item should be a [`Result`] with the ok variant being something that
     /// implements the [`Buf`] trait (e.g. `Vec<u8>` or `Bytes`). The error
@@ -301,7 +302,7 @@ where
 }
 
 // The code below is a manual expansion of the code that pin-project-lite would
-// generate. This is done because pin-project-lite fails by hitting the recusion
+// generate. This is done because pin-project-lite fails by hitting the recursion
 // limit on this struct. (Every line of documentation is handled recursively by
 // the macro.)
 
@@ -324,3 +325,22 @@ impl<S, B> StreamReader<S, B> {
         }
     }
 }
+
+impl<S: Sink<T, Error = E>, E, T> Sink<T> for StreamReader<S, E> {
+    type Error = E;
+    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.project().inner.poll_ready(cx)
+    }
+
+    fn start_send(self: Pin<&mut Self>, item: T) -> Result<(), Self::Error> {
+        self.project().inner.start_send(item)
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.project().inner.poll_flush(cx)
+    }
+
+    fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.project().inner.poll_close(cx)
+    }
+}

tokio-util/src/io/sync_bridge.rs

@@ -1,6 +1,7 @@
-use std::io::{BufRead, Read, Write};
+use std::io::{BufRead, Read, Seek, Write};
 use tokio::io::{
-    AsyncBufRead, AsyncBufReadExt, AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt,
+    AsyncBufRead, AsyncBufReadExt, AsyncRead, AsyncReadExt, AsyncSeek, AsyncSeekExt, AsyncWrite,
+    AsyncWriteExt,
 };
 
 /// Use a [`tokio::io::AsyncRead`] synchronously as a [`std::io::Read`] or
@@ -79,6 +80,13 @@ impl<T: AsyncWrite + Unpin> Write for SyncIoBridge<T> {
     }
 }
 
+impl<T: AsyncSeek + Unpin> Seek for SyncIoBridge<T> {
+    fn seek(&mut self, pos: std::io::SeekFrom) -> std::io::Result<u64> {
+        let src = &mut self.src;
+        self.rt.block_on(AsyncSeekExt::seek(src, pos))
+    }
+}
+
 // Because https://doc.rust-lang.org/std/io/trait.Write.html#method.is_write_vectored is at the time
 // of this writing still unstable, we expose this as part of a standalone method.
 impl<T: AsyncWrite> SyncIoBridge<T> {
@@ -140,4 +148,9 @@ impl<T: Unpin> SyncIoBridge<T> {
     pub fn new_with_handle(src: T, rt: tokio::runtime::Handle) -> Self {
         Self { src, rt }
     }
+
+    /// Consume this bridge, returning the underlying stream.
+    pub fn into_inner(self) -> T {
+        self.src
+    }
 }

tokio-util/src/lib.rs

@@ -57,151 +57,4 @@ pub mod either;
 
 pub use bytes;
 
-#[cfg(any(feature = "io", feature = "codec"))]
-mod util {
-    use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
-
-    use bytes::{Buf, BufMut};
-    use futures_core::ready;
-    use std::io::{self, IoSlice};
-    use std::mem::MaybeUninit;
-    use std::pin::Pin;
-    use std::task::{Context, Poll};
-
-    /// Try to read data from an `AsyncRead` into an implementer of the [`BufMut`] trait.
-    ///
-    /// [`BufMut`]: bytes::Buf
-    ///
-    /// # Example
-    ///
-    /// ```
-    /// use bytes::{Bytes, BytesMut};
-    /// use tokio_stream as stream;
-    /// use tokio::io::Result;
-    /// use tokio_util::io::{StreamReader, poll_read_buf};
-    /// use futures::future::poll_fn;
-    /// use std::pin::Pin;
-    /// # #[tokio::main]
-    /// # async fn main() -> std::io::Result<()> {
-    ///
-    /// // Create a reader from an iterator. This particular reader will always be
-    /// // ready.
-    /// let mut read = StreamReader::new(stream::iter(vec![Result::Ok(Bytes::from_static(&[0, 1, 2, 3]))]));
-    ///
-    /// let mut buf = BytesMut::new();
-    /// let mut reads = 0;
-    ///
-    /// loop {
-    ///     reads += 1;
-    ///     let n = poll_fn(|cx| poll_read_buf(Pin::new(&mut read), cx, &mut buf)).await?;
-    ///
-    ///     if n == 0 {
-    ///         break;
-    ///     }
-    /// }
-    ///
-    /// // one or more reads might be necessary.
-    /// assert!(reads >= 1);
-    /// assert_eq!(&buf[..], &[0, 1, 2, 3]);
-    /// # Ok(())
-    /// # }
-    /// ```
-    #[cfg_attr(not(feature = "io"), allow(unreachable_pub))]
-    pub fn poll_read_buf<T: AsyncRead, B: BufMut>(
-        io: Pin<&mut T>,
-        cx: &mut Context<'_>,
-        buf: &mut B,
-    ) -> Poll<io::Result<usize>> {
-        if !buf.has_remaining_mut() {
-            return Poll::Ready(Ok(0));
-        }
-
-        let n = {
-            let dst = buf.chunk_mut();
-
-            // Safety: `chunk_mut()` returns a `&mut UninitSlice`, and `UninitSlice` is a
-            // transparent wrapper around `[MaybeUninit<u8>]`.
-            let dst = unsafe { &mut *(dst as *mut _ as *mut [MaybeUninit<u8>]) };
-            let mut buf = ReadBuf::uninit(dst);
-            let ptr = buf.filled().as_ptr();
-            ready!(io.poll_read(cx, &mut buf)?);
-
-            // Ensure the pointer does not change from under us
-            assert_eq!(ptr, buf.filled().as_ptr());
-            buf.filled().len()
-        };
-
-        // Safety: This is guaranteed to be the number of initialized (and read)
-        // bytes due to the invariants provided by `ReadBuf::filled`.
-        unsafe {
-            buf.advance_mut(n);
-        }
-
-        Poll::Ready(Ok(n))
-    }
-
-    /// Try to write data from an implementer of the [`Buf`] trait to an
-    /// [`AsyncWrite`], advancing the buffer's internal cursor.
-    ///
-    /// This function will use [vectored writes] when the [`AsyncWrite`] supports
-    /// vectored writes.
-    ///
-    /// # Examples
-    ///
-    /// [`File`] implements [`AsyncWrite`] and [`Cursor<&[u8]>`] implements
-    /// [`Buf`]:
-    ///
-    /// ```no_run
-    /// use tokio_util::io::poll_write_buf;
-    /// use tokio::io;
-    /// use tokio::fs::File;
-    ///
-    /// use bytes::Buf;
-    /// use std::io::Cursor;
-    /// use std::pin::Pin;
-    /// use futures::future::poll_fn;
-    ///
-    /// #[tokio::main]
-    /// async fn main() -> io::Result<()> {
-    ///     let mut file = File::create("foo.txt").await?;
-    ///     let mut buf = Cursor::new(b"data to write");
-    ///
-    ///     // Loop until the entire contents of the buffer are written to
-    ///     // the file.
-    ///     while buf.has_remaining() {
-    ///         poll_fn(|cx| poll_write_buf(Pin::new(&mut file), cx, &mut buf)).await?;
-    ///     }
-    ///
-    ///     Ok(())
-    /// }
-    /// ```
-    ///
-    /// [`Buf`]: bytes::Buf
-    /// [`AsyncWrite`]: tokio::io::AsyncWrite
-    /// [`File`]: tokio::fs::File
-    /// [vectored writes]: tokio::io::AsyncWrite::poll_write_vectored
-    #[cfg_attr(not(feature = "io"), allow(unreachable_pub))]
-    pub fn poll_write_buf<T: AsyncWrite, B: Buf>(
-        io: Pin<&mut T>,
-        cx: &mut Context<'_>,
-        buf: &mut B,
-    ) -> Poll<io::Result<usize>> {
-        const MAX_BUFS: usize = 64;
-
-        if !buf.has_remaining() {
-            return Poll::Ready(Ok(0));
-        }
-
-        let n = if io.is_write_vectored() {
-            let mut slices = [IoSlice::new(&[]); MAX_BUFS];
-            let cnt = buf.chunks_vectored(&mut slices);
-            ready!(io.poll_write_vectored(cx, &slices[..cnt]))?
-        } else {
-            ready!(io.poll_write(cx, buf.chunk()))?
-        };
-
-        buf.advance(n);
-
-        Poll::Ready(Ok(n))
-    }
-}
+mod util;

tokio-util/src/sync/cancellation_token.rs

@@ -4,6 +4,7 @@ pub(crate) mod guard;
 mod tree_node;
 
 use crate::loom::sync::Arc;
+use crate::util::MaybeDangling;
 use core::future::Future;
 use core::pin::Pin;
 use core::task::{Context, Poll};
@@ -77,11 +78,23 @@ pin_project! {
     /// [`CancellationToken`] by value instead of using a reference.
     #[must_use = "futures do nothing unless polled"]
     pub struct WaitForCancellationFutureOwned {
-        // Since `future` is the first field, it is dropped before the
-        // cancellation_token field. This ensures that the reference inside the
-        // `Notified` remains valid.
+        // This field internally has a reference to the cancellation token, but camouflages
+        // the relationship with `'static`. To avoid Undefined Behavior, we must ensure
+        // that the reference is only used while the cancellation token is still alive. To
+        // do that, we ensure that the future is the first field, so that it is dropped
+        // before the cancellation token.
+        //
+        // We use `MaybeDanglingFuture` here because without it, the compiler could assert
+        // the reference inside `future` to be valid even after the destructor of that
+        // field runs. (Specifically, when the `WaitForCancellationFutureOwned` is passed
+        // as an argument to a function, the reference can be asserted to be valid for the
+        // rest of that function.) To avoid that, we use `MaybeDangling` which tells the
+        // compiler that the reference stored inside it might not be valid.
+        //
+        // See <https://users.rust-lang.org/t/unsafe-code-review-semi-owning-weak-rwlock-t-guard/95706>
+        // for more info.
         #[pin]
-        future: tokio::sync::futures::Notified<'static>,
+        future: MaybeDangling<tokio::sync::futures::Notified<'static>>,
         cancellation_token: CancellationToken,
     }
 }
@@ -120,7 +133,7 @@ impl Default for CancellationToken {
 }
 
 impl CancellationToken {
-    /// Creates a new CancellationToken in the non-cancelled state.
+    /// Creates a new `CancellationToken` in the non-cancelled state.
     pub fn new() -> CancellationToken {
         CancellationToken {
             inner: Arc::new(tree_node::TreeNode::new()),
@@ -279,7 +292,7 @@ impl WaitForCancellationFutureOwned {
             // # Safety
             //
             // cancellation_token is dropped after future due to the field ordering.
-            future: unsafe { Self::new_future(&cancellation_token) },
+            future: MaybeDangling::new(unsafe { Self::new_future(&cancellation_token) }),
             cancellation_token,
         }
     }
@@ -320,8 +333,9 @@ impl Future for WaitForCancellationFutureOwned {
             // # Safety
             //
             // cancellation_token is dropped after future due to the field ordering.
-            this.future
-                .set(unsafe { Self::new_future(this.cancellation_token) });
+            this.future.set(MaybeDangling::new(unsafe {
+                Self::new_future(this.cancellation_token)
+            }));
         }
     }
 }

tokio-util/src/sync/cancellation_token/tree_node.rs

@@ -1,16 +1,16 @@
-//! This mod provides the logic for the inner tree structure of the CancellationToken.
+//! This mod provides the logic for the inner tree structure of the `CancellationToken`.
 //!
-//! CancellationTokens are only light handles with references to TreeNode.
-//! All the logic is actually implemented in the TreeNode.
+//! `CancellationTokens` are only light handles with references to [`TreeNode`].
+//! All the logic is actually implemented in the [`TreeNode`].
 //!
-//! A TreeNode is part of the cancellation tree and may have one parent and an arbitrary number of
+//! A [`TreeNode`] is part of the cancellation tree and may have one parent and an arbitrary number of
 //! children.
 //!
-//! A TreeNode can receive the request to perform a cancellation through a CancellationToken.
+//! A [`TreeNode`] can receive the request to perform a cancellation through a `CancellationToken`.
 //! This cancellation request will cancel the node and all of its descendants.
 //!
 //! As soon as a node cannot get cancelled any more (because it was already cancelled or it has no
-//! more CancellationTokens pointing to it any more), it gets removed from the tree, to keep the
+//! more `CancellationTokens` pointing to it any more), it gets removed from the tree, to keep the
 //! tree as small as possible.
 //!
 //! # Invariants
@@ -66,7 +66,7 @@ impl TreeNode {
     }
 }
 
-/// The data contained inside a TreeNode.
+/// The data contained inside a `TreeNode`.
 ///
 /// This struct exists so that the data of the node can be wrapped
 /// in a Mutex.
@@ -178,6 +178,8 @@ where
                 locked_node = node.inner.lock().unwrap();
                 locked_parent
             }
+            // https://github.com/tokio-rs/tokio/pull/6273#discussion_r1443752911
+            #[allow(clippy::unnecessary_literal_unwrap)]
             Err(TryLockError::Poisoned(err)) => Err(err).unwrap(),
         };
 
@@ -196,7 +198,7 @@ where
 /// `parent` MUST have been a parent of the node when they both got locked,
 /// otherwise there is a potential for a deadlock as invariant #2 would be violated.
 ///
-/// To acquire the locks for node and parent, use [with_locked_node_and_parent].
+/// To acquire the locks for node and parent, use [`with_locked_node_and_parent`].
 fn move_children_to_parent(node: &mut Inner, parent: &mut Inner) {
     // Pre-allocate in the parent, for performance
     parent.children.reserve(node.children.len());
@@ -214,7 +216,7 @@ fn move_children_to_parent(node: &mut Inner, parent: &mut Inner) {
 /// Removes a child from the parent.
 ///
 /// `parent` MUST be the parent of `node`.
-/// To acquire the locks for node and parent, use [with_locked_node_and_parent].
+/// To acquire the locks for node and parent, use [`with_locked_node_and_parent`].
 fn remove_child(parent: &mut Inner, mut node: MutexGuard<'_, Inner>) {
     // Query the position from where to remove a node
     let pos = node.parent_idx;

tokio-util/src/sync/mpsc.rs

@@ -303,7 +303,7 @@ impl<T> Clone for PollSender<T> {
     }
 }
 
-impl<T: Send + 'static> Sink<T> for PollSender<T> {
+impl<T: Send> Sink<T> for PollSender<T> {
     type Error = PollSendError<T>;
 
     fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {

tokio-util/src/sync/poll_semaphore.rs

@@ -29,7 +29,7 @@ impl PollSemaphore {
 
     /// Closes the semaphore.
     pub fn close(&self) {
-        self.semaphore.close()
+        self.semaphore.close();
     }
 
     /// Obtain a clone of the inner semaphore.

tokio-util/src/sync/reusable_box.rs

@@ -1,7 +1,6 @@
 use std::alloc::Layout;
 use std::fmt;
-use std::future::Future;
-use std::marker::PhantomData;
+use std::future::{self, Future};
 use std::mem::{self, ManuallyDrop};
 use std::pin::Pin;
 use std::ptr;
@@ -61,7 +60,7 @@ impl<'a, T> ReusableBoxFuture<'a, T> {
             F: Future + Send + 'a,
         {
             // future::Pending<T> is a ZST so this never allocates.
-            let boxed = mem::replace(&mut this.boxed, Box::pin(Pending(PhantomData)));
+            let boxed = mem::replace(&mut this.boxed, Box::pin(future::pending()));
             reuse_pin_box(boxed, future, |boxed| this.boxed = Pin::from(boxed))
         }
 
@@ -156,16 +155,3 @@ impl<O, F: FnOnce() -> O> Drop for CallOnDrop<O, F> {
         f();
     }
 }
-
-/// The same as `std::future::Pending<T>`; we can't use that type directly because on rustc
-/// versions <1.60 it didn't unconditionally implement `Send`.
-// FIXME: use `std::future::Pending<T>` once the MSRV is >=1.60
-struct Pending<T>(PhantomData<fn() -> T>);
-
-impl<T> Future for Pending<T> {
-    type Output = T;
-
-    fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
-        Poll::Pending
-    }
-}