chore: prepare Tokio v1.16.1 release (#4438)

* Several of tokio's features (e.g. the channel implementation) do not
  need a runtime to work, and can be compiled and used for
  wasm32-unknown-unknown targets
* This change enables running tests for the `sync` and `macros` features
  so that we can note any regressions there

.cargo/audit.toml

@@ -0,0 +1,8 @@
+# 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

@@ -0,0 +1,22 @@
+version: 2.1        
+jobs:
+  test-arm:
+    machine:
+      image: ubuntu-2004:202101-01
+    resource_class: arm.medium
+    steps:
+      - checkout
+      - run:
+          name: Install Rust
+          command: |
+            curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs -o rustup.sh
+            chmod +x rustup.sh
+            ./rustup.sh -y
+            source "$HOME"/.cargo/env
+      # Only run Tokio tests
+      - run: cargo test --all-features -p tokio
+
+workflows:
+  ci:
+    jobs:
+      - test-arm

.cirrus.yml

@@ -1,15 +1,45 @@
 freebsd_instance:
   image: freebsd-12-2-release-amd64
+env:
+  RUSTFLAGS: -D warnings
 
 # Test FreeBSD in a full VM on cirrus-ci.com.  Test the i686 target too, in the
 # same VM.  The binary will be built in 32-bit mode, but will execute on a
 # 64-bit kernel and in a 64-bit environment.  Our tests don't execute any of
 # the system's binaries, so the environment shouldn't matter.
 task:
-  name: FreeBSD
+  name: FreeBSD 64-bit
+  setup_script:
+    - pkg install -y bash curl
+    - curl https://sh.rustup.rs -sSf --output rustup.sh
+    - sh rustup.sh -y --profile minimal --default-toolchain stable
+    - . $HOME/.cargo/env
+    - |
+      echo "~~~~ rustc --version ~~~~"
+      rustc --version
+  test_script:
+    - . $HOME/.cargo/env
+    - cargo test --all --all-features
+
+task:
+  name: FreeBSD docs
   env:
-    LOOM_MAX_PREEMPTIONS: 2
-    RUSTFLAGS: -Dwarnings
+    RUSTFLAGS: --cfg docsrs
+    RUSTDOCFLAGS: --cfg docsrs -Dwarnings
+  setup_script:
+    - pkg install -y bash curl
+    - curl https://sh.rustup.rs -sSf --output rustup.sh
+    - sh rustup.sh -y --profile minimal --default-toolchain nightly-2022-01-12
+    - . $HOME/.cargo/env
+    - |
+      echo "~~~~ rustc --version ~~~~"
+      rustc --version
+  test_script:
+    - . $HOME/.cargo/env
+    - cargo doc --lib --no-deps --all-features --document-private-items
+
+task:
+  name: FreeBSD 32-bit
   setup_script:
     - pkg install -y bash curl
     - curl https://sh.rustup.rs -sSf --output rustup.sh
@@ -21,9 +51,4 @@ task:
       rustc --version
   test_script:
     - . $HOME/.cargo/env
-    - cargo test --all --all-features
-    - cargo doc --all --no-deps
-  i686_test_script:
-    - . $HOME/.cargo/env
-    - |
-      cargo test --all --all-features --target i686-unknown-freebsd
+    - cargo test --all --all-features --target i686-unknown-freebsd

.clippy.toml

@@ -0,0 +1 @@
+msrv = "1.46"

.github/FUNDING.yml

@@ -0,0 +1,3 @@
+# These are supported funding model platforms
+
+github: [tokio-rs]

.github/labeler.yml

@@ -0,0 +1,8 @@
+
+R-loom:
+- tokio/src/sync/*
+- tokio/src/sync/**/*
+- tokio-util/src/sync/*
+- tokio-util/src/sync/**/*
+- tokio/src/runtime/*
+- tokio/src/runtime/**/*

.github/workflows/bench.yml

@@ -1,55 +0,0 @@
-name: Benchmark
-on:
-  push:
-    branches:
-      - master
-
-jobs:
-  benchmark:
-    name: Benchmark
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        bench:
-          - rt_multi_threaded
-          - sync_mpsc
-          - sync_rwlock
-          - sync_semaphore
-    steps:
-      - uses: actions/checkout@v2
-      - name: Install Rust
-        run: rustup update stable
-
-      # Run benchmark with `go test -bench` and stores the output to a file
-      - name: Run benchmark
-        run: cargo bench --bench ${{ matrix.bench }} | tee ../output.txt
-        working-directory: benches
-
-      # Download previous benchmark result from cache (if exists)
-      - name: Download previous benchmark data
-        uses: actions/cache@v1
-        with:
-          path: ./cache
-          key: ${{ runner.os }}-benchmark
-
-      # Run `github-action-benchmark` action
-      - name: Store benchmark result
-        uses: rhysd/github-action-benchmark@v1
-        with:
-          name: ${{ matrix.bench }}
-          # What benchmark tool the output.txt came from
-          tool: 'cargo'
-          # Where the output from the benchmark tool is stored
-          output-file-path: output.txt
-          # # Where the previous data file is stored
-          # external-data-json-path: ./cache/benchmark-data.json
-          # Workflow will fail when an alert happens
-          fail-on-alert: true
-          # GitHub API token to make a commit comment
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          # Enable alert commit comment
-          comment-on-alert: true
-          alert-comment-cc-users: '@tokio-rs/maintainers'
-          auto-push: true
-
-      # Upload the updated cache file for the next job by actions/cache

.github/workflows/ci.yml

@@ -9,8 +9,12 @@ name: CI
 env:
   RUSTFLAGS: -Dwarnings
   RUST_BACKTRACE: 1
-  nightly: nightly-2021-04-25
-  minrust: 1.45.2
+  nightly: nightly-2022-01-12
+  minrust: 1.46
+
+defaults:
+  run:
+    shell: bash
 
 jobs:
   # Depends on all action sthat are required for a "successful" CI run.
@@ -20,6 +24,7 @@ jobs:
     needs:
       - test
       - test-unstable
+      - test-parking_lot
       - miri
       - cross
       - features
@@ -27,8 +32,11 @@ jobs:
       - fmt
       - clippy
       - docs
-      - loom
       - valgrind
+      - loom-compile
+      - check-readme
+      - test-hyper
+      - wasm32-unknown-unknown
     steps:
       - run: exit 0
 
@@ -45,6 +53,7 @@ jobs:
       - uses: actions/checkout@v2
       - name: Install Rust
         run: rustup update stable
+      - uses: Swatinem/rust-cache@v1
       - name: Install cargo-hack
         run: cargo install cargo-hack
 
@@ -75,6 +84,27 @@ jobs:
         # bench.yml workflow runs benchmarks only on linux.
         if: startsWith(matrix.os, 'ubuntu')
 
+  test-parking_lot:
+    # The parking_lot crate has a feature called send_guard which changes when
+    # some of its types are Send. Tokio has some measures in place to prevent
+    # this from affecting when Tokio types are Send, and this test exists to
+    # ensure that those measures are working.
+    #
+    # This relies on the potentially affected Tokio type being listed in
+    # `tokio/tokio/tests/async_send_sync.rs`.
+    name: compile tests with parking lot send guards
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install Rust
+        run: rustup update stable
+      - uses: Swatinem/rust-cache@v1
+      - name: Enable parking_lot send_guard feature
+        # Inserts the line "plsend = ["parking_lot/send_guard"]" right after [features]
+        run: sed -i '/\[features\]/a plsend = ["parking_lot/send_guard"]' tokio/Cargo.toml
+      - name: Compile tests with all features enabled
+        run: cargo build --workspace --all-features --tests
+
   valgrind:
     name: valgrind
     runs-on: ubuntu-latest
@@ -82,6 +112,7 @@ jobs:
       - uses: actions/checkout@v2
       - name: Install Rust
         run: rustup update stable
+      - uses: Swatinem/rust-cache@v1
 
       - name: Install Valgrind
         run: |
@@ -95,7 +126,7 @@ jobs:
 
       # Run with valgrind
       - name: Run valgrind test-mem
-        run: valgrind  --leak-check=full --show-leak-kinds=all ./target/debug/test-mem
+        run: valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all ./target/debug/test-mem
 
       # Compile tests
       - name: cargo build test-process-signal
@@ -104,7 +135,7 @@ jobs:
 
       # Run with valgrind
       - name: Run valgrind test-process-signal
-        run: valgrind --leak-check=full --show-leak-kinds=all ./target/debug/test-process-signal
+        run: valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all ./target/debug/test-process-signal
 
   test-unstable:
     name: test tokio full --unstable
@@ -119,10 +150,11 @@ jobs:
       - uses: actions/checkout@v2
       - name: Install Rust
         run: rustup update stable
+      - uses: Swatinem/rust-cache@v1
 
       # Run `tokio` with "unstable" cfg flag.
       - name: test tokio full --cfg unstable
-        run: cargo test --features full
+        run: cargo test --all-features
         working-directory: tokio
         env:
           RUSTFLAGS: --cfg tokio_unstable -Dwarnings
@@ -136,6 +168,7 @@ jobs:
         with:
           toolchain: ${{ env.nightly }}
           override: true
+      - uses: Swatinem/rust-cache@v1
       - name: Install Miri
         run: |
           set -e
@@ -155,6 +188,7 @@ jobs:
         with:
           toolchain: ${{ env.nightly }}
           override: true
+      - uses: Swatinem/rust-cache@v1
       - name: asan
         run: cargo test --all-features --target x86_64-unknown-linux-gnu --lib -- --test-threads 1
         working-directory: tokio
@@ -180,6 +214,7 @@ jobs:
           toolchain: stable
           target: ${{ matrix.target }}
           override: true
+      - uses: Swatinem/rust-cache@v1
       - uses: actions-rs/cargo@v1
         with:
           use-cross: true
@@ -195,6 +230,7 @@ jobs:
         with:
           toolchain: ${{ env.nightly }}
           override: true
+      - uses: Swatinem/rust-cache@v1
       - name: Install cargo-hack
         run: cargo install cargo-hack
 
@@ -216,7 +252,7 @@ jobs:
         with:
           toolchain: ${{ env.minrust }}
           override: true
-
+      - uses: Swatinem/rust-cache@v1
       - name: "test --workspace --all-features"
         run: cargo check --workspace --all-features
 
@@ -229,6 +265,7 @@ jobs:
         with:
           toolchain: ${{ env.nightly }}
           override: true
+      - uses: Swatinem/rust-cache@v1
       - name: Install cargo-hack
         run: cargo install cargo-hack
       - name: "check --all-features -Z minimal-versions"
@@ -238,7 +275,17 @@ jobs:
           cargo hack --remove-dev-deps --workspace
           # Update Cargo.lock to minimal version dependencies.
           cargo update -Z minimal-versions
-          cargo check --all-features
+          cargo hack check --all-features --ignore-private
+      - name: "check --all-features --unstable -Z minimal-versions"
+        env:
+          RUSTFLAGS: --cfg tokio_unstable -Dwarnings
+        run: |
+          # Remove dev-dependencies from Cargo.toml to prevent the next `cargo update`
+          # from determining minimal versions based on dev-dependencies.
+          cargo hack --remove-dev-deps --workspace
+          # Update Cargo.lock to minimal version dependencies.
+          cargo update -Z minimal-versions
+          cargo hack check --all-features --ignore-private
 
   fmt:
     name: fmt
@@ -247,15 +294,14 @@ jobs:
       - uses: actions/checkout@v2
       - name: Install Rust
         run: rustup update stable
-      - name: Install rustfmt
-        run: rustup component add rustfmt
+      - uses: Swatinem/rust-cache@v1
 
       # Check fmt
       - name: "rustfmt --check"
         # Workaround for rust-lang/cargo#7732
         run: |
-          if ! rustfmt --check --edition 2018 $(find . -name '*.rs' -print); then
-            printf "Please run \`rustfmt --edition 2018 \$(find . -name '*.rs' -print)\` to fix rustfmt errors.\nSee CONTRIBUTING.md for more details.\n" >&2
+          if ! rustfmt --check --edition 2018 $(git ls-files '*.rs'); then
+            printf "Please run \`rustfmt --edition 2018 \$(git ls-files '*.rs')\` to fix rustfmt errors.\nSee CONTRIBUTING.md for more details.\n" >&2
             exit 1
           fi
 
@@ -265,7 +311,8 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Install Rust
-        run: rustup update ${{ env.minrust }} && rustup default ${{ env.minrust }}
+        run: rustup update 1.57 && rustup default 1.57
+      - uses: Swatinem/rust-cache@v1
       - name: Install clippy
         run: rustup component add clippy
 
@@ -282,33 +329,80 @@ jobs:
         with:
           toolchain: ${{ env.nightly }}
           override: true
-
+      - uses: Swatinem/rust-cache@v1
       - name: "doc --lib --all-features"
         run: cargo doc --lib --no-deps --all-features --document-private-items
         env:
+          RUSTFLAGS: --cfg docsrs
           RUSTDOCFLAGS: --cfg docsrs -Dwarnings
 
-  loom:
-    name: loom
+  loom-compile:
+    name: build loom tests
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        scope:
-          - --skip loom_pool
-          - loom_pool::group_a
-          - loom_pool::group_b
-          - loom_pool::group_c
-          - loom_pool::group_d
-          - time::driver
     steps:
       - uses: actions/checkout@v2
       - name: Install Rust
         run: rustup update stable
-
-      - name: loom ${{ matrix.scope }}
-        run: cargo test --lib --release --features full -- --nocapture $SCOPE
+      - uses: Swatinem/rust-cache@v1
+      - name: build --cfg loom
+        run: cargo test --no-run --lib --features full
         working-directory: tokio
         env:
           RUSTFLAGS: --cfg loom --cfg tokio_unstable -Dwarnings
-          LOOM_MAX_PREEMPTIONS: 2
-          SCOPE: ${{ matrix.scope }}
+
+  check-readme:
+    name: Check README
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Verify that both READMEs are identical
+        run: diff README.md tokio/README.md
+
+      - name: Verify that Tokio version is up to date in README
+        working-directory: tokio
+        run: grep -q "$(sed '/^version = /!d' Cargo.toml | head -n1)" README.md
+
+  test-hyper:
+    name: Test hyper
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os:
+          - windows-latest
+          - ubuntu-latest
+          - macos-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install Rust
+        run: rustup update stable
+      - uses: Swatinem/rust-cache@v1
+      - name: Test hyper
+        run: |
+          set -x
+          git clone https://github.com/hyperium/hyper.git
+          cd hyper
+          # checkout the latest release because HEAD maybe contains breakage.
+          tag=$(git describe --abbrev=0 --tags)
+          git checkout "${tag}"
+          echo '[workspace]' >>Cargo.toml
+          echo '[patch.crates-io]' >>Cargo.toml
+          echo 'tokio = { path = "../tokio" }' >>Cargo.toml
+          echo 'tokio-util = { path = "../tokio-util" }' >>Cargo.toml
+          echo 'tokio-stream = { path = "../tokio-stream" }' >>Cargo.toml
+          echo 'tokio-test = { path = "../tokio-test" }' >>Cargo.toml
+          git diff
+          cargo test --features full
+
+  wasm32-unknown-unknown:
+    name: test tokio for wasm32-unknown-unknown
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install Rust
+        run: rustup update stable
+      - uses: Swatinem/rust-cache@v1
+      - name: Install wasm-pack
+        run: curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh
+      - name: test tokio
+        run: wasm-pack test --node -- --features "macros sync"
+        working-directory: tokio

.github/workflows/labeler.yml

@@ -0,0 +1,14 @@
+name: "Pull Request Labeler"
+on:
+- pull_request_target
+
+# See .github/labeler.yml file
+
+jobs:
+  triage:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/labeler@v3
+      with:
+        repo-token: "${{ secrets.GITHUB_TOKEN }}"
+        sync-labels: true

.github/workflows/loom.yml

@@ -0,0 +1,40 @@
+on:
+  push:
+    branches: ["master", "tokio-*.x"]
+  pull_request:
+    types: [labeled, opened, synchronize, reopened]
+    branches: ["master", "tokio-*.x"]
+
+name: Loom
+
+env:
+  RUSTFLAGS: -Dwarnings
+  RUST_BACKTRACE: 1
+
+jobs:
+  loom:
+    name: loom
+    # base_ref is null when it's not a pull request
+    if: contains(github.event.pull_request.labels.*.name, 'R-loom') || (github.base_ref == null)
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        scope:
+          - --skip loom_pool
+          - loom_pool::group_a
+          - loom_pool::group_b
+          - loom_pool::group_c
+          - loom_pool::group_d
+          - time::driver
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install Rust
+        run: rustup update stable
+      - uses: Swatinem/rust-cache@v1
+      - name: loom ${{ matrix.scope }}
+        run: cargo test --lib --release --features full -- --nocapture $SCOPE
+        working-directory: tokio
+        env:
+          RUSTFLAGS: --cfg loom --cfg tokio_unstable -Dwarnings
+          LOOM_MAX_PREEMPTIONS: 2
+          SCOPE: ${{ matrix.scope }}

.github/workflows/stress-test.yml

@@ -17,7 +17,7 @@ jobs:
       - uses: actions/checkout@v2
       - name: Install Rust
         run: rustup update stable
-
+      - uses: Swatinem/rust-cache@v1
       - name: Install Valgrind
         run: |
           sudo apt-get update -y

CONTRIBUTING.md

@@ -139,6 +139,14 @@ correctly, use this command:
 RUSTDOCFLAGS="--cfg docsrs" cargo +nightly doc --all-features
 ```
 
+To build documentation including Tokio's unstable features, it is necessary to
+pass `--cfg tokio_unstable` to both RustDoc *and* rustc. To build the
+documentation for unstable features, use this command:
+
+```
+RUSTDOCFLAGS="--cfg docsrs --cfg tokio_unstable" RUSTFLAGS="--cfg tokio_unstable" cargo +nightly doc --all-features
+```
+
 There is currently a [bug in cargo] that means documentation cannot be built
 from the root of the workspace. If you `cd` into the `tokio` subdirectory the
 command shown above will work.
@@ -150,7 +158,7 @@ command below instead:
 
 ```
 # Mac or Linux
-rustfmt --check --edition 2018 $(find . -name '*.rs' -print)
+rustfmt --check --edition 2018 $(git ls-files '*.rs')
 
 # Powershell
 Get-ChildItem . -Filter "*.rs" -Recurse | foreach { rustfmt --check --edition 2018 $_.FullName }

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2021 Tokio Contributors
+Copyright (c) 2022 Tokio Contributors
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated

README.md

@@ -56,7 +56,7 @@ Make sure you activated the full features of the tokio crate on Cargo.toml:
 
 ```toml
 [dependencies]
-tokio = { version = "1.5.0", features = ["full"] }
+tokio = { version = "1.16.1", features = ["full"] }
 ```
 Then, on your main.rs:
 
@@ -66,7 +66,7 @@ use tokio::io::{AsyncReadExt, AsyncWriteExt};
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let mut listener = TcpListener::bind("127.0.0.1:8080").await?;
+    let listener = TcpListener::bind("127.0.0.1:8080").await?;
 
     loop {
         let (mut socket, _) = listener.accept().await?;
@@ -140,8 +140,7 @@ several other libraries, including:
 
 * [`tower`]: A library of modular and reusable components for building robust networking clients and servers.
 
-* [`tracing`] (formerly `tokio-trace`): A framework for application-level
-  tracing and async-aware diagnostics.
+* [`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.
 
@@ -164,9 +163,36 @@ several other libraries, including:
 
 ## Supported Rust Versions
 
-Tokio is built against the latest stable release. The minimum supported version is 1.45.
-The current Tokio version is not guaranteed to build on Rust versions earlier than the
-minimum supported version.
+Tokio is built against the latest stable release. The minimum supported version
+is 1.46.  The current Tokio version is not guaranteed to build on Rust versions
+earlier than the minimum supported version.
+
+## Release schedule
+
+Tokio doesn't follow a fixed release schedule, but we typically make one to two
+new minor releases each month. We make patch releases for bugfixes as necessary.
+
+## Bug patching policy
+
+For the purposes of making patch releases with bugfixes, we have designated
+certain minor releases as LTS (long term support) releases. Whenever a bug
+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:
+
+ * `1.8.x` - LTS release until February 2022.
+ * `1.14.x` - LTS release until June 2022.
+
+Each LTS release will continue to receive backported fixes for at least half 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 `1.8.x` patch release, you
+can use the following dependency specification:
+```text
+tokio = { version = "~1.8", features = [...] }
+```
 
 ## License
 

benches/Cargo.toml

@@ -9,7 +9,7 @@ tokio = { version = "1.5.0", path = "../tokio", features = ["full"] }
 bencher = "0.1.5"
 
 [dev-dependencies]
-tokio-util = { version = "0.6.6", path = "../tokio-util", features = ["full"] }
+tokio-util = { version = "0.7.0", path = "../tokio-util", features = ["full"] }
 tokio-stream = { path = "../tokio-stream" }
 
 [target.'cfg(unix)'.dependencies]

benches/fs.rs

@@ -21,7 +21,7 @@ fn rt() -> tokio::runtime::Runtime {
 const BLOCK_COUNT: usize = 1_000;
 
 const BUFFER_SIZE: usize = 4096;
-const DEV_ZERO: &'static str = "/dev/zero";
+const DEV_ZERO: &str = "/dev/zero";
 
 fn async_read_codec(b: &mut Bencher) {
     let rt = rt();

benches/rt_multi_threaded.rs

@@ -1,4 +1,4 @@
-//! Benchmark implementation details of the theaded scheduler. These benches are
+//! Benchmark implementation details of the threaded scheduler. These benches are
 //! intended to be used as a form of regression testing and not as a general
 //! purpose benchmark demonstrating real-world performance.
 

benches/spawn.rs

@@ -2,63 +2,83 @@
 //! 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};
 
 async fn work() -> usize {
     let val = 1 + 1;
+    tokio::task::yield_now().await;
     black_box(val)
 }
 
-fn basic_scheduler_local_spawn(bench: &mut Bencher) {
+fn basic_scheduler_spawn(bench: &mut Bencher) {
     let runtime = tokio::runtime::Builder::new_current_thread()
         .build()
         .unwrap();
-    runtime.block_on(async {
-        bench.iter(|| {
-            let h = tokio::spawn(work());
-            black_box(h);
-        })
-    });
-}
-
-fn threaded_scheduler_local_spawn(bench: &mut Bencher) {
-    let runtime = tokio::runtime::Builder::new_current_thread()
-        .build()
-        .unwrap();
-    runtime.block_on(async {
-        bench.iter(|| {
-            let h = tokio::spawn(work());
-            black_box(h);
-        })
-    });
-}
-
-fn basic_scheduler_remote_spawn(bench: &mut Bencher) {
-    let runtime = tokio::runtime::Builder::new_current_thread()
-        .build()
-        .unwrap();
-
     bench.iter(|| {
-        let h = runtime.spawn(work());
-        black_box(h);
+        runtime.block_on(async {
+            let h = tokio::spawn(work());
+            assert_eq!(h.await.unwrap(), 2);
+        });
     });
 }
 
-fn threaded_scheduler_remote_spawn(bench: &mut Bencher) {
-    let runtime = tokio::runtime::Builder::new_multi_thread().build().unwrap();
-
+fn basic_scheduler_spawn10(bench: &mut Bencher) {
+    let runtime = tokio::runtime::Builder::new_current_thread()
+        .build()
+        .unwrap();
     bench.iter(|| {
-        let h = runtime.spawn(work());
-        black_box(h);
+        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) {
+    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);
+        });
+    });
+}
+
+fn threaded_scheduler_spawn10(bench: &mut Bencher) {
+    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);
+            }
+        });
     });
 }
 
 bencher::benchmark_group!(
     spawn,
-    basic_scheduler_local_spawn,
-    threaded_scheduler_local_spawn,
-    basic_scheduler_remote_spawn,
-    threaded_scheduler_remote_spawn
+    basic_scheduler_spawn,
+    basic_scheduler_spawn10,
+    threaded_scheduler_spawn,
+    threaded_scheduler_spawn10,
 );
 
 bencher::benchmark_main!(spawn);

examples/Cargo.toml

@@ -5,14 +5,14 @@ publish = false
 edition = "2018"
 
 # If you copy one of the examples into a new project, you should be using
-# [dependencies] instead.
+# [dependencies] instead, and delete the **path**.
 [dev-dependencies]
-tokio = { version = "1.0.0", path = "../tokio",features = ["full", "tracing"] }
-tokio-util = { version = "0.6.3", path = "../tokio-util",features = ["full"] }
+tokio = { version = "1.0.0", path = "../tokio", features = ["full", "tracing"] }
+tokio-util = { version = "0.7.0", path = "../tokio-util", features = ["full"] }
 tokio-stream = { version = "0.1", path = "../tokio-stream" }
 
 tracing = "0.1"
-tracing-subscriber = { version = "0.2.7", default-features = false, features = ["fmt", "ansi", "env-filter", "chrono", "tracing-log"] }
+tracing-subscriber = { version = "0.3.1", default-features = false, features = ["fmt", "ansi", "env-filter", "tracing-log"] }
 bytes = "1.0.0"
 futures = { version = "0.3.0", features = ["thread-pool"]}
 http = "0.2"
@@ -20,9 +20,12 @@ serde = "1.0"
 serde_derive = "1.0"
 serde_json = "1.0"
 httparse = "1.0"
-time = "0.1"
+httpdate = "1.0"
 once_cell = "1.5.2"
+rand = "0.8.3"
 
+[target.'cfg(windows)'.dev-dependencies.winapi]
+version = "0.3.8"
 
 [[example]]
 name = "chat"
@@ -76,3 +79,15 @@ path = "custom-executor.rs"
 [[example]]
 name = "custom-executor-tokio-context"
 path = "custom-executor-tokio-context.rs"
+
+[[example]]
+name = "named-pipe"
+path = "named-pipe.rs"
+
+[[example]]
+name = "named-pipe-ready"
+path = "named-pipe-ready.rs"
+
+[[example]]
+name = "named-pipe-multi-client"
+path = "named-pipe-multi-client.rs"

examples/named-pipe-multi-client.rs

@@ -0,0 +1,98 @@
+use std::io;
+
+#[cfg(windows)]
+async fn windows_main() -> io::Result<()> {
+    use std::time::Duration;
+    use tokio::io::{AsyncReadExt, AsyncWriteExt};
+    use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+    use tokio::time;
+    use winapi::shared::winerror;
+
+    const PIPE_NAME: &str = r"\\.\pipe\named-pipe-multi-client";
+    const N: usize = 10;
+
+    // The first server needs to be constructed early so that clients can
+    // be correctly connected. Otherwise a waiting client will error.
+    //
+    // Here we also make use of `first_pipe_instance`, which will ensure
+    // that there are no other servers up and running already.
+    let mut server = ServerOptions::new()
+        .first_pipe_instance(true)
+        .create(PIPE_NAME)?;
+
+    let server = tokio::spawn(async move {
+        // Artificial workload.
+        time::sleep(Duration::from_secs(1)).await;
+
+        for _ in 0..N {
+            // Wait for client to connect.
+            server.connect().await?;
+            let mut inner = server;
+
+            // Construct the next server to be connected before sending the one
+            // we already have of onto a task. This ensures that the server
+            // isn't closed (after it's done in the task) before a new one is
+            // available. Otherwise the client might error with
+            // `io::ErrorKind::NotFound`.
+            server = ServerOptions::new().create(PIPE_NAME)?;
+
+            let _ = tokio::spawn(async move {
+                let mut buf = vec![0u8; 4];
+                inner.read_exact(&mut buf).await?;
+                inner.write_all(b"pong").await?;
+                Ok::<_, io::Error>(())
+            });
+        }
+
+        Ok::<_, io::Error>(())
+    });
+
+    let mut clients = Vec::new();
+
+    for _ in 0..N {
+        clients.push(tokio::spawn(async move {
+            // This showcases a generic connect loop.
+            //
+            // We immediately try to create a client, if it's not found or
+            // the pipe is busy we use the specialized wait function on the
+            // client builder.
+            let mut client = loop {
+                match ClientOptions::new().open(PIPE_NAME) {
+                    Ok(client) => break client,
+                    Err(e) if e.raw_os_error() == Some(winerror::ERROR_PIPE_BUSY as i32) => (),
+                    Err(e) => return Err(e),
+                }
+
+                time::sleep(Duration::from_millis(5)).await;
+            };
+
+            let mut buf = [0u8; 4];
+            client.write_all(b"ping").await?;
+            client.read_exact(&mut buf).await?;
+            Ok::<_, io::Error>(buf)
+        }));
+    }
+
+    for client in clients {
+        let result = client.await?;
+        assert_eq!(&result?[..], b"pong");
+    }
+
+    server.await??;
+    Ok(())
+}
+
+#[tokio::main]
+async fn main() -> io::Result<()> {
+    #[cfg(windows)]
+    {
+        windows_main().await?;
+    }
+
+    #[cfg(not(windows))]
+    {
+        println!("Named pipes are only supported on Windows!");
+    }
+
+    Ok(())
+}

examples/named-pipe-ready.rs

@@ -0,0 +1,161 @@
+use std::io;
+
+#[cfg(windows)]
+async fn windows_main() -> io::Result<()> {
+    use tokio::io::Interest;
+    use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+
+    const PIPE_NAME: &str = r"\\.\pipe\named-pipe-single-client";
+
+    let server = ServerOptions::new().create(PIPE_NAME)?;
+
+    let server = tokio::spawn(async move {
+        // Note: we wait for a client to connect.
+        server.connect().await?;
+
+        let buf = {
+            let mut read_buf = [0u8; 5];
+            let mut read_buf_cursor = 0;
+
+            loop {
+                server.readable().await?;
+
+                let buf = &mut read_buf[read_buf_cursor..];
+
+                match server.try_read(buf) {
+                    Ok(n) => {
+                        read_buf_cursor += n;
+
+                        if read_buf_cursor == read_buf.len() {
+                            break;
+                        }
+                    }
+                    Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                        continue;
+                    }
+                    Err(e) => {
+                        return Err(e);
+                    }
+                }
+            }
+
+            read_buf
+        };
+
+        {
+            let write_buf = b"pong\n";
+            let mut write_buf_cursor = 0;
+
+            loop {
+                let buf = &write_buf[write_buf_cursor..];
+
+                if buf.is_empty() {
+                    break;
+                }
+
+                server.writable().await?;
+
+                match server.try_write(buf) {
+                    Ok(n) => {
+                        write_buf_cursor += n;
+                    }
+                    Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                        continue;
+                    }
+                    Err(e) => {
+                        return Err(e);
+                    }
+                }
+            }
+        }
+
+        Ok::<_, io::Error>(buf)
+    });
+
+    let client = tokio::spawn(async move {
+        // There's no need to use a connect loop here, since we know that the
+        // server is already up - `open` was called before spawning any of the
+        // tasks.
+        let client = ClientOptions::new().open(PIPE_NAME)?;
+
+        let mut read_buf = [0u8; 5];
+        let mut read_buf_cursor = 0;
+        let write_buf = b"ping\n";
+        let mut write_buf_cursor = 0;
+
+        loop {
+            let mut interest = Interest::READABLE;
+            if write_buf_cursor < write_buf.len() {
+                interest |= Interest::WRITABLE;
+            }
+
+            let ready = client.ready(interest).await?;
+
+            if ready.is_readable() {
+                let buf = &mut read_buf[read_buf_cursor..];
+
+                match client.try_read(buf) {
+                    Ok(n) => {
+                        read_buf_cursor += n;
+
+                        if read_buf_cursor == read_buf.len() {
+                            break;
+                        }
+                    }
+                    Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                        continue;
+                    }
+                    Err(e) => {
+                        return Err(e);
+                    }
+                }
+            }
+
+            if ready.is_writable() {
+                let buf = &write_buf[write_buf_cursor..];
+
+                if buf.is_empty() {
+                    continue;
+                }
+
+                match client.try_write(buf) {
+                    Ok(n) => {
+                        write_buf_cursor += n;
+                    }
+                    Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                        continue;
+                    }
+                    Err(e) => {
+                        return Err(e);
+                    }
+                }
+            }
+        }
+
+        let buf = String::from_utf8_lossy(&read_buf).into_owned();
+
+        Ok::<_, io::Error>(buf)
+    });
+
+    let (server, client) = tokio::try_join!(server, client)?;
+
+    assert_eq!(server?, *b"ping\n");
+    assert_eq!(client?, "pong\n");
+
+    Ok(())
+}
+
+#[tokio::main]
+async fn main() -> io::Result<()> {
+    #[cfg(windows)]
+    {
+        windows_main().await?;
+    }
+
+    #[cfg(not(windows))]
+    {
+        println!("Named pipes are only supported on Windows!");
+    }
+
+    Ok(())
+}

examples/named-pipe.rs

@@ -0,0 +1,60 @@
+use std::io;
+
+#[cfg(windows)]
+async fn windows_main() -> io::Result<()> {
+    use tokio::io::AsyncWriteExt;
+    use tokio::io::{AsyncBufReadExt, BufReader};
+    use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+
+    const PIPE_NAME: &str = r"\\.\pipe\named-pipe-single-client";
+
+    let server = ServerOptions::new().create(PIPE_NAME)?;
+
+    let server = tokio::spawn(async move {
+        // Note: we wait for a client to connect.
+        server.connect().await?;
+
+        let mut server = BufReader::new(server);
+
+        let mut buf = String::new();
+        server.read_line(&mut buf).await?;
+        server.write_all(b"pong\n").await?;
+        Ok::<_, io::Error>(buf)
+    });
+
+    let client = tokio::spawn(async move {
+        // There's no need to use a connect loop here, since we know that the
+        // server is already up - `open` was called before spawning any of the
+        // tasks.
+        let client = ClientOptions::new().open(PIPE_NAME)?;
+
+        let mut client = BufReader::new(client);
+
+        let mut buf = String::new();
+        client.write_all(b"ping\n").await?;
+        client.read_line(&mut buf).await?;
+        Ok::<_, io::Error>(buf)
+    });
+
+    let (server, client) = tokio::try_join!(server, client)?;
+
+    assert_eq!(server?, "ping\n");
+    assert_eq!(client?, "pong\n");
+
+    Ok(())
+}
+
+#[tokio::main]
+async fn main() -> io::Result<()> {
+    #[cfg(windows)]
+    {
+        windows_main().await?;
+    }
+
+    #[cfg(not(windows))]
+    {
+        println!("Named pipes are only supported on Windows!");
+    }
+
+    Ok(())
+}

examples/tinydb.rs

@@ -149,7 +149,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
 }
 
 fn handle_request(line: &str, db: &Arc<Database>) -> Response {
-    let request = match Request::parse(&line) {
+    let request = match Request::parse(line) {
         Ok(req) => req,
         Err(e) => return Response::Error { msg: e },
     };

examples/tinyhttp.rs

@@ -221,8 +221,9 @@ mod date {
     use std::cell::RefCell;
     use std::fmt::{self, Write};
     use std::str;
+    use std::time::SystemTime;
 
-    use time::{self, Duration};
+    use httpdate::HttpDate;
 
     pub struct Now(());
 
@@ -252,22 +253,26 @@ mod date {
     struct LastRenderedNow {
         bytes: [u8; 128],
         amt: usize,
-        next_update: time::Timespec,
+        unix_date: u64,
     }
 
     thread_local!(static LAST: RefCell<LastRenderedNow> = RefCell::new(LastRenderedNow {
         bytes: [0; 128],
         amt: 0,
-        next_update: time::Timespec::new(0, 0),
+        unix_date: 0,
     }));
 
     impl fmt::Display for Now {
         fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
             LAST.with(|cache| {
                 let mut cache = cache.borrow_mut();
-                let now = time::get_time();
-                if now >= cache.next_update {
-                    cache.update(now);
+                let now = SystemTime::now();
+                let now_unix = now
+                    .duration_since(SystemTime::UNIX_EPOCH)
+                    .map(|since_epoch| since_epoch.as_secs())
+                    .unwrap_or(0);
+                if cache.unix_date != now_unix {
+                    cache.update(now, now_unix);
                 }
                 f.write_str(cache.buffer())
             })
@@ -279,11 +284,10 @@ mod date {
             str::from_utf8(&self.bytes[..self.amt]).unwrap()
         }
 
-        fn update(&mut self, now: time::Timespec) {
+        fn update(&mut self, now: SystemTime, now_unix: u64) {
             self.amt = 0;
-            write!(LocalBuffer(self), "{}", time::at(now).rfc822()).unwrap();
-            self.next_update = now + Duration::seconds(1);
-            self.next_update.nsec = 0;
+            self.unix_date = now_unix;
+            write!(LocalBuffer(self), "{}", HttpDate::from(now)).unwrap();
         }
     }
 

tests-build/tests/fail/macros_core_no_default.stderr

@@ -4,4 +4,4 @@ error: The default runtime flavor is `multi_thread`, but the `rt-multi-thread` f
 3 | #[tokio::main]
   | ^^^^^^^^^^^^^^
   |
-  = note: this error originates in an attribute macro (in Nightly builds, run with -Z macro-backtrace for more info)
+  = note: this error originates in the attribute macro `tokio::main` (in Nightly builds, run with -Z macro-backtrace for more info)

tests-build/tests/fail/macros_type_mismatch.rs

@@ -7,12 +7,6 @@ async fn missing_semicolon_or_return_type() {
 
 #[tokio::main]
 async fn missing_return_type() {
-    /* TODO(taiki-e): one of help messages still wrong
-    help: consider using a semicolon here
-       |
-    16 |     return Ok(());;
-       |
-    */
     return Ok(());
 }
 
@@ -21,9 +15,9 @@ async fn extra_semicolon() -> Result<(), ()> {
     /* TODO(taiki-e): help message still wrong
     help: try using a variant of the expected enum
        |
-    29 |     Ok(Ok(());)
+    23 |     Ok(Ok(());)
        |
-    29 |     Err(Ok(());)
+    23 |     Err(Ok(());)
        |
     */
     Ok(());

tests-build/tests/fail/macros_type_mismatch.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
- --> $DIR/macros_type_mismatch.rs:5:5
+ --> tests/fail/macros_type_mismatch.rs:5:5
   |
 5 |     Ok(())
   |     ^^^^^^ expected `()`, found enum `Result`
@@ -9,43 +9,36 @@ error[E0308]: mismatched types
 help: consider using a semicolon here
   |
 5 |     Ok(());
-  |           ^
+  |           +
 help: try adding a return type
   |
 4 | async fn missing_semicolon_or_return_type() -> Result<(), _> {
-  |                                             ^^^^^^^^^^^^^^^^
+  |                                             ++++++++++++++++
 
 error[E0308]: mismatched types
-  --> $DIR/macros_type_mismatch.rs:16:5
+  --> tests/fail/macros_type_mismatch.rs:10:5
    |
-16 |     return Ok(());
+9  | async fn missing_return_type() {
+   |                                - help: try adding a return type: `-> Result<(), _>`
+10 |     return Ok(());
    |     ^^^^^^^^^^^^^^ expected `()`, found enum `Result`
    |
    = note: expected unit type `()`
                    found enum `Result<(), _>`
-help: consider using a semicolon here
-   |
-16 |     return Ok(());;
-   |                   ^
-help: try adding a return type
-   |
-9  | async fn missing_return_type() -> Result<(), _> {
-   |                                ^^^^^^^^^^^^^^^^
 
 error[E0308]: mismatched types
-  --> $DIR/macros_type_mismatch.rs:29:5
+  --> tests/fail/macros_type_mismatch.rs:23:5
    |
-20 | async fn extra_semicolon() -> Result<(), ()> {
+14 | async fn extra_semicolon() -> Result<(), ()> {
    |                               -------------- expected `Result<(), ()>` because of return type
 ...
-29 |     Ok(());
+23 |     Ok(());
    |     ^^^^^^^ expected enum `Result`, found `()`
    |
    = note:   expected enum `Result<(), ()>`
            found unit type `()`
-help: try using a variant of the expected enum
+help: try adding an expression at the end of the block
    |
-29 |     Ok(Ok(());)
-   |
-29 |     Err(Ok(());)
+23 ~     Ok(());;
+24 +     Ok(())
    |

tests-build/tests/macros.rs

@@ -5,6 +5,12 @@ fn compile_fail_full() {
     #[cfg(feature = "full")]
     t.pass("tests/pass/forward_args_and_output.rs");
 
+    #[cfg(feature = "full")]
+    t.pass("tests/pass/macros_main_return.rs");
+
+    #[cfg(feature = "full")]
+    t.pass("tests/pass/macros_main_loop.rs");
+
     #[cfg(feature = "full")]
     t.compile_fail("tests/fail/macros_invalid_input.rs");
 

tests-build/tests/macros_clippy.rs

@@ -0,0 +1,7 @@
+#[cfg(feature = "full")]
+#[tokio::test]
+async fn test_with_semicolon_without_return_type() {
+    #![deny(clippy::semicolon_if_nothing_returned)]
+
+    dbg!(0);
+}

tests-build/tests/pass/macros_main_loop.rs

@@ -0,0 +1,14 @@
+use tests_build::tokio;
+
+#[tokio::main]
+async fn main() -> Result<(), ()> {
+    loop {
+        if !never() {
+            return Ok(());
+        }
+    }
+}
+
+fn never() -> bool {
+    std::time::Instant::now() > std::time::Instant::now()
+}

tests-build/tests/pass/macros_main_return.rs

@@ -0,0 +1,6 @@
+use tests_build::tokio;
+
+#[tokio::main]
+async fn main() -> Result<(), ()> {
+    return Ok(());
+}

tokio-macros/CHANGELOG.md

@@ -1,3 +1,54 @@
+# 1.7.0 (December 15th, 2021)
+
+- macros: address remainging clippy::semicolon_if_nothing_returned warning ([#4252])
+
+[#4252]: https://github.com/tokio-rs/tokio/pull/4252
+
+# 1.6.0 (November 16th, 2021)
+
+- macros: fix mut patterns in `select!` macro ([#4211])
+
+[#4211]: https://github.com/tokio-rs/tokio/pull/4211
+
+# 1.5.1 (October 29th, 2021)
+
+- macros: fix type resolution error in `#[tokio::main]` ([#4176])
+
+[#4176]: https://github.com/tokio-rs/tokio/pull/4176
+
+# 1.5.0 (October 13th, 2021)
+
+- macros: make tokio-macros attributes more IDE friendly ([#4162])
+
+[#4162]: https://github.com/tokio-rs/tokio/pull/4162
+
+# 1.4.1 (September 30th, 2021)
+
+Reverted: run `current_thread` inside `LocalSet` ([#4027])
+
+# 1.4.0 (September 29th, 2021)
+
+(yanked)
+
+### Changed
+
+- macros: run `current_thread` inside `LocalSet` ([#4027])
+- macros: explicitly relaxed clippy lint for `.expect()` in runtime entry macro ([#4030])
+
+### Fixed
+
+- macros: fix invalid error messages in functions wrapped with `#[main]` or `#[test]` ([#4067])
+
+[#4027]: https://github.com/tokio-rs/tokio/pull/4027
+[#4030]: https://github.com/tokio-rs/tokio/pull/4030
+[#4067]: https://github.com/tokio-rs/tokio/pull/4067
+
+# 1.3.0 (July 7, 2021)
+
+- macros: don't trigger `clippy::unwrap_used` ([#3926])
+
+[#3926]: https://github.com/tokio-rs/tokio/pull/3926
+
 # 1.2.0 (May 14, 2021)
 
 - macros: forward input arguments in `#[tokio::test]` ([#3691])

tokio-macros/Cargo.toml

@@ -2,17 +2,15 @@
 name = "tokio-macros"
 # When releasing to crates.io:
 # - Remove path dependencies
-# - Update doc url
-#   - Cargo.toml
 # - Update CHANGELOG.md.
 # - Create "tokio-macros-1.0.x" git tag.
-version = "1.2.0"
+version = "1.7.0"
 edition = "2018"
+rust-version = "1.46"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
-documentation = "https://docs.rs/tokio-macros/1.2.0/tokio_macros"
 description = """
 Tokio's proc macros.
 """

tokio-macros/LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2021 Tokio Contributors
+Copyright (c) 2022 Tokio Contributors
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated

tokio-macros/src/entry.rs

@@ -1,6 +1,10 @@
 use proc_macro::TokenStream;
 use proc_macro2::Span;
 use quote::{quote, quote_spanned, ToTokens};
+use syn::parse::Parser;
+
+// syn::AttributeArgs does not implement syn::Parse
+type AttributeArgs = syn::punctuated::Punctuated<syn::NestedMeta, syn::Token![,]>;
 
 #[derive(Clone, Copy, PartialEq)]
 enum RuntimeFlavor {
@@ -27,6 +31,13 @@ struct FinalConfig {
     start_paused: Option<bool>,
 }
 
+/// Config used in case of the attribute not being able to build a valid config
+const DEFAULT_ERROR_CONFIG: FinalConfig = FinalConfig {
+    flavor: RuntimeFlavor::CurrentThread,
+    worker_threads: None,
+    start_paused: None,
+};
+
 struct Configuration {
     rt_multi_thread_available: bool,
     default_flavor: RuntimeFlavor,
@@ -184,13 +195,13 @@ fn parse_bool(bool: syn::Lit, span: Span, field: &str) -> Result<bool, syn::Erro
     }
 }
 
-fn parse_knobs(
-    mut input: syn::ItemFn,
-    args: syn::AttributeArgs,
+fn build_config(
+    input: syn::ItemFn,
+    args: AttributeArgs,
     is_test: bool,
     rt_multi_thread: bool,
-) -> Result<TokenStream, syn::Error> {
-    if input.sig.asyncness.take().is_none() {
+) -> Result<FinalConfig, syn::Error> {
+    if input.sig.asyncness.is_none() {
         let msg = "the `async` keyword is missing from the function declaration";
         return Err(syn::Error::new_spanned(input.sig.fn_token, msg));
     }
@@ -201,12 +212,15 @@ fn parse_knobs(
     for arg in args {
         match arg {
             syn::NestedMeta::Meta(syn::Meta::NameValue(namevalue)) => {
-                let ident = namevalue.path.get_ident();
-                if ident.is_none() {
-                    let msg = "Must have specified ident";
-                    return Err(syn::Error::new_spanned(namevalue, msg));
-                }
-                match ident.unwrap().to_string().to_lowercase().as_str() {
+                let ident = namevalue
+                    .path
+                    .get_ident()
+                    .ok_or_else(|| {
+                        syn::Error::new_spanned(&namevalue, "Must have specified ident")
+                    })?
+                    .to_string()
+                    .to_lowercase();
+                match ident.as_str() {
                     "worker_threads" => {
                         config.set_worker_threads(
                             namevalue.lit.clone(),
@@ -239,12 +253,11 @@ fn parse_knobs(
                 }
             }
             syn::NestedMeta::Meta(syn::Meta::Path(path)) => {
-                let ident = path.get_ident();
-                if ident.is_none() {
-                    let msg = "Must have specified ident";
-                    return Err(syn::Error::new_spanned(path, msg));
-                }
-                let name = ident.unwrap().to_string().to_lowercase();
+                let name = path
+                    .get_ident()
+                    .ok_or_else(|| syn::Error::new_spanned(&path, "Must have specified ident"))?
+                    .to_string()
+                    .to_lowercase();
                 let msg = match name.as_str() {
                     "threaded_scheduler" | "multi_thread" => {
                         format!(
@@ -276,7 +289,11 @@ fn parse_knobs(
         }
     }
 
-    let config = config.build()?;
+    config.build()
+}
+
+fn parse_knobs(mut input: syn::ItemFn, is_test: bool, config: FinalConfig) -> TokenStream {
+    input.sig.asyncness = None;
 
     // If type mismatch occurs, the current rustc points to the last statement.
     let (last_stmt_start_span, last_stmt_end_span) = {
@@ -321,16 +338,32 @@ fn parse_knobs(
 
     let body = &input.block;
     let brace_token = input.block.brace_token;
+    let (tail_return, tail_semicolon) = match body.stmts.last() {
+        Some(syn::Stmt::Semi(syn::Expr::Return(_), _)) => (quote! { return }, quote! { ; }),
+        Some(syn::Stmt::Semi(..)) | Some(syn::Stmt::Local(..)) | None => {
+            match &input.sig.output {
+                syn::ReturnType::Type(_, ty) if matches!(&**ty, syn::Type::Tuple(ty) if ty.elems.is_empty()) =>
+                {
+                    (quote! {}, quote! { ; }) // unit
+                }
+                syn::ReturnType::Default => (quote! {}, quote! { ; }), // unit
+                syn::ReturnType::Type(..) => (quote! {}, quote! {}),   // ! or another
+            }
+        }
+        _ => (quote! {}, quote! {}),
+    };
     input.block = syn::parse2(quote_spanned! {last_stmt_end_span=>
         {
-            #rt
+            let body = async #body;
+            #[allow(clippy::expect_used)]
+            #tail_return #rt
                 .enable_all()
                 .build()
-                .unwrap()
-                .block_on(async #body)
+                .expect("Failed building the Runtime")
+                .block_on(body)#tail_semicolon
         }
     })
-    .unwrap();
+    .expect("Parsing failure");
     input.block.brace_token = brace_token;
 
     let result = quote! {
@@ -338,36 +371,58 @@ fn parse_knobs(
         #input
     };
 
-    Ok(result.into())
+    result.into()
+}
+
+fn token_stream_with_error(mut tokens: TokenStream, error: syn::Error) -> TokenStream {
+    tokens.extend(TokenStream::from(error.into_compile_error()));
+    tokens
 }
 
 #[cfg(not(test))] // Work around for rust-lang/rust#62127
 pub(crate) fn main(args: TokenStream, item: TokenStream, rt_multi_thread: bool) -> TokenStream {
-    let input = syn::parse_macro_input!(item as syn::ItemFn);
-    let args = syn::parse_macro_input!(args as syn::AttributeArgs);
+    // If any of the steps for this macro fail, we still want to expand to an item that is as close
+    // to the expected output as possible. This helps out IDEs such that completions and other
+    // related features keep working.
+    let input: syn::ItemFn = match syn::parse(item.clone()) {
+        Ok(it) => it,
+        Err(e) => return token_stream_with_error(item, e),
+    };
 
-    if input.sig.ident == "main" && !input.sig.inputs.is_empty() {
+    let config = if input.sig.ident == "main" && !input.sig.inputs.is_empty() {
         let msg = "the main function cannot accept arguments";
-        return syn::Error::new_spanned(&input.sig.ident, msg)
-            .to_compile_error()
-            .into();
-    }
+        Err(syn::Error::new_spanned(&input.sig.ident, msg))
+    } else {
+        AttributeArgs::parse_terminated
+            .parse(args)
+            .and_then(|args| build_config(input.clone(), args, false, rt_multi_thread))
+    };
 
-    parse_knobs(input, args, false, rt_multi_thread).unwrap_or_else(|e| e.to_compile_error().into())
+    match config {
+        Ok(config) => parse_knobs(input, false, config),
+        Err(e) => token_stream_with_error(parse_knobs(input, false, DEFAULT_ERROR_CONFIG), e),
+    }
 }
 
 pub(crate) fn test(args: TokenStream, item: TokenStream, rt_multi_thread: bool) -> TokenStream {
-    let input = syn::parse_macro_input!(item as syn::ItemFn);
-    let args = syn::parse_macro_input!(args as syn::AttributeArgs);
+    // If any of the steps for this macro fail, we still want to expand to an item that is as close
+    // to the expected output as possible. This helps out IDEs such that completions and other
+    // related features keep working.
+    let input: syn::ItemFn = match syn::parse(item.clone()) {
+        Ok(it) => it,
+        Err(e) => return token_stream_with_error(item, e),
+    };
+    let config = if let Some(attr) = input.attrs.iter().find(|attr| attr.path.is_ident("test")) {
+        let msg = "second test attribute is supplied";
+        Err(syn::Error::new_spanned(&attr, msg))
+    } else {
+        AttributeArgs::parse_terminated
+            .parse(args)
+            .and_then(|args| build_config(input.clone(), args, true, rt_multi_thread))
+    };
 
-    for attr in &input.attrs {
-        if attr.path.is_ident("test") {
-            let msg = "second test attribute is supplied";
-            return syn::Error::new_spanned(&attr, msg)
-                .to_compile_error()
-                .into();
-        }
+    match config {
+        Ok(config) => parse_knobs(input, true, config),
+        Err(e) => token_stream_with_error(parse_knobs(input, true, DEFAULT_ERROR_CONFIG), e),
     }
-
-    parse_knobs(input, args, true, rt_multi_thread).unwrap_or_else(|e| e.to_compile_error().into())
 }

tokio-macros/src/lib.rs

@@ -5,7 +5,6 @@
     rust_2018_idioms,
     unreachable_pub
 )]
-#![cfg_attr(docsrs, deny(broken_intra_doc_links))]
 #![doc(test(
     no_crate_inject,
     attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))
@@ -329,3 +328,11 @@ pub fn test_fail(_args: TokenStream, _item: TokenStream) -> TokenStream {
 pub fn select_priv_declare_output_enum(input: TokenStream) -> TokenStream {
     select::declare_output_enum(input)
 }
+
+/// Implementation detail of the `select!` macro. This macro is **not** intended
+/// to be used as part of the public API and is permitted to change.
+#[proc_macro]
+#[doc(hidden)]
+pub fn select_priv_clean_pattern(input: TokenStream) -> TokenStream {
+    select::clean_pattern_macro(input)
+}

tokio-macros/src/select.rs

@@ -41,3 +41,70 @@ pub(crate) fn declare_output_enum(input: TokenStream) -> TokenStream {
         pub(super) type Mask = #mask;
     })
 }
+
+pub(crate) fn clean_pattern_macro(input: TokenStream) -> TokenStream {
+    // If this isn't a pattern, we return the token stream as-is. The select!
+    // macro is using it in a location requiring a pattern, so an error will be
+    // emitted there.
+    let mut input: syn::Pat = match syn::parse(input.clone()) {
+        Ok(it) => it,
+        Err(_) => return input,
+    };
+
+    clean_pattern(&mut input);
+    quote::ToTokens::into_token_stream(input).into()
+}
+
+// Removes any occurrences of ref or mut in the provided pattern.
+fn clean_pattern(pat: &mut syn::Pat) {
+    match pat {
+        syn::Pat::Box(_box) => {}
+        syn::Pat::Lit(_literal) => {}
+        syn::Pat::Macro(_macro) => {}
+        syn::Pat::Path(_path) => {}
+        syn::Pat::Range(_range) => {}
+        syn::Pat::Rest(_rest) => {}
+        syn::Pat::Verbatim(_tokens) => {}
+        syn::Pat::Wild(_underscore) => {}
+        syn::Pat::Ident(ident) => {
+            ident.by_ref = None;
+            ident.mutability = None;
+            if let Some((_at, pat)) = &mut ident.subpat {
+                clean_pattern(&mut *pat);
+            }
+        }
+        syn::Pat::Or(or) => {
+            for case in or.cases.iter_mut() {
+                clean_pattern(case);
+            }
+        }
+        syn::Pat::Slice(slice) => {
+            for elem in slice.elems.iter_mut() {
+                clean_pattern(elem);
+            }
+        }
+        syn::Pat::Struct(struct_pat) => {
+            for field in struct_pat.fields.iter_mut() {
+                clean_pattern(&mut field.pat);
+            }
+        }
+        syn::Pat::Tuple(tuple) => {
+            for elem in tuple.elems.iter_mut() {
+                clean_pattern(elem);
+            }
+        }
+        syn::Pat::TupleStruct(tuple) => {
+            for elem in tuple.pat.elems.iter_mut() {
+                clean_pattern(elem);
+            }
+        }
+        syn::Pat::Reference(reference) => {
+            reference.mutability = None;
+            clean_pattern(&mut *reference.pat);
+        }
+        syn::Pat::Type(type_pat) => {
+            clean_pattern(&mut *type_pat.pat);
+        }
+        _ => {}
+    }
+}

tokio-stream/CHANGELOG.md

@@ -1,3 +1,36 @@
+# 0.1.8 (October 29, 2021)
+
+- stream: add `From<Receiver<T>>` impl for receiver streams ([#4080])
+- stream: impl `FromIterator` for `StreamMap` ([#4052])
+- signal: make windows docs for signal module show up on unix builds ([#3770])
+
+[#3770]: https://github.com/tokio-rs/tokio/pull/3770
+[#4052]: https://github.com/tokio-rs/tokio/pull/4052
+[#4080]: https://github.com/tokio-rs/tokio/pull/4080
+
+# 0.1.7 (July 7, 2021)
+
+### Fixed
+
+- sync: fix watch wrapper ([#3914])
+- time: fix `Timeout::size_hint` ([#3902])
+
+[#3902]: https://github.com/tokio-rs/tokio/pull/3902
+[#3914]: https://github.com/tokio-rs/tokio/pull/3914
+
+# 0.1.6 (May 14, 2021)
+
+### Added
+
+- stream: implement `Error` and `Display` for `BroadcastStreamRecvError` ([#3745])
+
+### Fixed
+
+- stream: avoid yielding in `AllFuture` and `AnyFuture` ([#3625])
+
+[#3745]: https://github.com/tokio-rs/tokio/pull/3745
+[#3625]: https://github.com/tokio-rs/tokio/pull/3625
+
 # 0.1.5 (March 20, 2021)
 
 ### Fixed

tokio-stream/Cargo.toml

@@ -2,17 +2,15 @@
 name = "tokio-stream"
 # When releasing to crates.io:
 # - Remove path dependencies
-# - Update doc url
-#   - Cargo.toml
 # - Update CHANGELOG.md.
 # - Create "tokio-stream-0.1.x" git tag.
-version = "0.1.5"
+version = "0.1.8"
 edition = "2018"
+rust-version = "1.46"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
-documentation = "https://docs.rs/tokio-stream/0.1.5/tokio_stream"
 description = """
 Utilities to work with `Stream` and `tokio`.
 """
@@ -30,8 +28,8 @@ signal = ["tokio/signal"]
 [dependencies]
 futures-core = { version = "0.3.0" }
 pin-project-lite = "0.2.0"
-tokio = { version = "1.2.0", path = "../tokio", features = ["sync"] }
-tokio-util = { version = "0.6.3", path = "../tokio-util", optional = true }
+tokio = { version = "1.8.0", path = "../tokio", features = ["sync"] }
+tokio-util = { version = "0.7.0", path = "../tokio-util", optional = true }
 
 [dev-dependencies]
 tokio = { version = "1.2.0", path = "../tokio", features = ["full", "test-util"] }
@@ -44,3 +42,8 @@ proptest = "1"
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
+# Issue #3770
+#
+# This should allow `docsrs` to be read across projects, so that `tokio-stream`
+# can pick up stubbed types exported by `tokio`.
+rustc-args = ["--cfg", "docsrs"]

tokio-stream/LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2021 Tokio Contributors
+Copyright (c) 2022 Tokio Contributors
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated

tokio-stream/src/lib.rs

@@ -10,7 +10,6 @@
     unreachable_pub
 )]
 #![cfg_attr(docsrs, feature(doc_cfg))]
-#![cfg_attr(docsrs, deny(broken_intra_doc_links))]
 #![doc(test(
     no_crate_inject,
     attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))

tokio-stream/src/stream_ext.rs

@@ -1,3 +1,4 @@
+use core::future::Future;
 use futures_core::Stream;
 
 mod all;
@@ -27,6 +28,9 @@ use fuse::Fuse;
 mod map;
 use map::Map;
 
+mod map_while;
+use map_while::MapWhile;
+
 mod merge;
 use merge::Merge;
 
@@ -39,15 +43,18 @@ use skip::Skip;
 mod skip_while;
 use skip_while::SkipWhile;
 
-mod try_next;
-use try_next::TryNext;
-
 mod take;
 use take::Take;
 
 mod take_while;
 use take_while::TakeWhile;
 
+mod then;
+use then::Then;
+
+mod try_next;
+use try_next::TryNext;
+
 cfg_time! {
     mod timeout;
     use timeout::Timeout;
@@ -197,6 +204,93 @@ pub trait StreamExt: Stream {
         Map::new(self, f)
     }
 
+    /// Map this stream's items to a different type for as long as determined by
+    /// the provided closure. A stream of the target type will be returned,
+    /// which will yield elements until the closure returns `None`.
+    ///
+    /// The provided closure is executed over all elements of this stream as
+    /// they are made available, until it returns `None`. It is executed inline
+    /// with calls to [`poll_next`](Stream::poll_next). Once `None` is returned,
+    /// the underlying stream will not be polled again.
+    ///
+    /// Note that this function consumes the stream passed into it and returns a
+    /// wrapped version of it, similar to the [`Iterator::map_while`] method in the
+    /// standard library.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// use tokio_stream::{self as stream, StreamExt};
+    ///
+    /// let stream = stream::iter(1..=10);
+    /// let mut stream = stream.map_while(|x| {
+    ///     if x < 4 {
+    ///         Some(x + 3)
+    ///     } else {
+    ///         None
+    ///     }
+    /// });
+    /// assert_eq!(stream.next().await, Some(4));
+    /// assert_eq!(stream.next().await, Some(5));
+    /// assert_eq!(stream.next().await, Some(6));
+    /// assert_eq!(stream.next().await, None);
+    /// # }
+    /// ```
+    fn map_while<T, F>(self, f: F) -> MapWhile<Self, F>
+    where
+        F: FnMut(Self::Item) -> Option<T>,
+        Self: Sized,
+    {
+        MapWhile::new(self, f)
+    }
+
+    /// Maps this stream's items asynchronously to a different type, returning a
+    /// new stream of the resulting type.
+    ///
+    /// The provided closure is executed over all elements of this stream as
+    /// they are made available, and the returned future is executed. Only one
+    /// future is executed at the time.
+    ///
+    /// Note that this function consumes the stream passed into it and returns a
+    /// wrapped version of it, similar to the existing `then` methods in the
+    /// standard library.
+    ///
+    /// Be aware that if the future is not `Unpin`, then neither is the `Stream`
+    /// returned by this method. To handle this, you can use `tokio::pin!` as in
+    /// the example below or put the stream in a `Box` with `Box::pin(stream)`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// use tokio_stream::{self as stream, StreamExt};
+    ///
+    /// async fn do_async_work(value: i32) -> i32 {
+    ///     value + 3
+    /// }
+    ///
+    /// let stream = stream::iter(1..=3);
+    /// let stream = stream.then(do_async_work);
+    ///
+    /// tokio::pin!(stream);
+    ///
+    /// assert_eq!(stream.next().await, Some(4));
+    /// assert_eq!(stream.next().await, Some(5));
+    /// assert_eq!(stream.next().await, Some(6));
+    /// # }
+    /// ```
+    fn then<F, Fut>(self, f: F) -> Then<Self, Fut, F>
+    where
+        F: FnMut(Self::Item) -> Fut,
+        Fut: Future,
+        Self: Sized,
+    {
+        Then::new(self, f)
+    }
+
     /// Combine two streams into one by interleaving the output of both as it
     /// is produced.
     ///
@@ -515,7 +609,7 @@ pub trait StreamExt: Stream {
     /// Skip elements from the underlying stream while the provided predicate
     /// resolves to `true`.
     ///
-    /// This function, like [`Iterator::skip_while`], will ignore elemets from the
+    /// This function, like [`Iterator::skip_while`], will ignore elements from the
     /// stream until the predicate `f` resolves to `false`. Once one element
     /// returns false, the rest of the elements will be yielded.
     ///

tokio-stream/src/stream_ext/collect.rs

@@ -66,17 +66,17 @@ where
         use Poll::Ready;
 
         loop {
-            let mut me = self.as_mut().project();
+            let me = self.as_mut().project();
 
             let item = match ready!(me.stream.poll_next(cx)) {
                 Some(item) => item,
                 None => {
-                    return Ready(U::finalize(sealed::Internal, &mut me.collection));
+                    return Ready(U::finalize(sealed::Internal, me.collection));
                 }
             };
 
-            if !U::extend(sealed::Internal, &mut me.collection, item) {
-                return Ready(U::finalize(sealed::Internal, &mut me.collection));
+            if !U::extend(sealed::Internal, me.collection, item) {
+                return Ready(U::finalize(sealed::Internal, me.collection));
             }
         }
     }
@@ -113,7 +113,7 @@ impl<T: AsRef<str>> sealed::FromStreamPriv<T> for String {
     }
 
     fn finalize(_: sealed::Internal, collection: &mut String) -> String {
-        mem::replace(collection, String::new())
+        mem::take(collection)
     }
 }
 
@@ -132,7 +132,7 @@ impl<T> sealed::FromStreamPriv<T> for Vec<T> {
     }
 
     fn finalize(_: sealed::Internal, collection: &mut Vec<T>) -> Vec<T> {
-        mem::replace(collection, vec![])
+        mem::take(collection)
     }
 }
 

tokio-stream/src/stream_ext/map_while.rs

@@ -0,0 +1,52 @@
+use crate::Stream;
+
+use core::fmt;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+use pin_project_lite::pin_project;
+
+pin_project! {
+    /// Stream for the [`map_while`](super::StreamExt::map_while) method.
+    #[must_use = "streams do nothing unless polled"]
+    pub struct MapWhile<St, F> {
+        #[pin]
+        stream: St,
+        f: F,
+    }
+}
+
+impl<St, F> fmt::Debug for MapWhile<St, F>
+where
+    St: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("MapWhile")
+            .field("stream", &self.stream)
+            .finish()
+    }
+}
+
+impl<St, F> MapWhile<St, F> {
+    pub(super) fn new(stream: St, f: F) -> Self {
+        MapWhile { stream, f }
+    }
+}
+
+impl<St, F, T> Stream for MapWhile<St, F>
+where
+    St: Stream,
+    F: FnMut(St::Item) -> Option<T>,
+{
+    type Item = T;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>> {
+        let me = self.project();
+        let f = me.f;
+        me.stream.poll_next(cx).map(|opt| opt.and_then(f))
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let (_, upper) = self.stream.size_hint();
+        (0, upper)
+    }
+}

tokio-stream/src/stream_ext/then.rs

@@ -0,0 +1,83 @@
+use crate::Stream;
+
+use core::fmt;
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+use pin_project_lite::pin_project;
+
+pin_project! {
+    /// Stream for the [`then`](super::StreamExt::then) method.
+    #[must_use = "streams do nothing unless polled"]
+    pub struct Then<St, Fut, F> {
+        #[pin]
+        stream: St,
+        #[pin]
+        future: Option<Fut>,
+        f: F,
+    }
+}
+
+impl<St, Fut, F> fmt::Debug for Then<St, Fut, F>
+where
+    St: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Then")
+            .field("stream", &self.stream)
+            .finish()
+    }
+}
+
+impl<St, Fut, F> Then<St, Fut, F> {
+    pub(super) fn new(stream: St, f: F) -> Self {
+        Then {
+            stream,
+            future: None,
+            f,
+        }
+    }
+}
+
+impl<St, F, Fut> Stream for Then<St, Fut, F>
+where
+    St: Stream,
+    Fut: Future,
+    F: FnMut(St::Item) -> Fut,
+{
+    type Item = Fut::Output;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Fut::Output>> {
+        let mut me = self.project();
+
+        loop {
+            if let Some(future) = me.future.as_mut().as_pin_mut() {
+                match future.poll(cx) {
+                    Poll::Ready(item) => {
+                        me.future.set(None);
+                        return Poll::Ready(Some(item));
+                    }
+                    Poll::Pending => return Poll::Pending,
+                }
+            }
+
+            match me.stream.as_mut().poll_next(cx) {
+                Poll::Ready(Some(item)) => {
+                    me.future.set(Some((me.f)(item)));
+                }
+                Poll::Ready(None) => return Poll::Ready(None),
+                Poll::Pending => return Poll::Pending,
+            }
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let future_len = if self.future.is_some() { 1 } else { 0 };
+        let (lower, upper) = self.stream.size_hint();
+
+        let lower = lower.saturating_add(future_len);
+        let upper = upper.and_then(|upper| upper.checked_add(future_len));
+
+        (lower, upper)
+    }
+}

tokio-stream/src/stream_ext/timeout.rs

@@ -69,7 +69,18 @@ impl<S: Stream> Stream for Timeout<S> {
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        self.stream.size_hint()
+        let (lower, upper) = self.stream.size_hint();
+
+        // The timeout stream may insert an error before and after each message
+        // from the underlying stream, but no more than one error between each
+        // message. Hence the upper bound is computed as 2x+1.
+
+        // Using a helper function to enable use of question mark operator.
+        fn twice_plus_one(value: Option<usize>) -> Option<usize> {
+            value?.checked_mul(2)?.checked_add(1)
+        }
+
+        (lower, twice_plus_one(upper))
     }
 }
 

tokio-stream/src/stream_map.rs

@@ -364,11 +364,11 @@ impl<K, V> StreamMap<K, V> {
     /// # Examples
     ///
     /// ```
-    /// use std::collections::HashMap;
+    /// use tokio_stream::{StreamMap, pending};
     ///
-    /// let mut a = HashMap::new();
+    /// let mut a = StreamMap::new();
     /// assert!(a.is_empty());
-    /// a.insert(1, "a");
+    /// a.insert(1, pending::<i32>());
     /// assert!(!a.is_empty());
     /// ```
     pub fn is_empty(&self) -> bool {
@@ -568,6 +568,32 @@ where
     }
 }
 
+impl<K, V> std::iter::FromIterator<(K, V)> for StreamMap<K, V>
+where
+    K: Hash + Eq,
+{
+    fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
+        let iterator = iter.into_iter();
+        let (lower_bound, _) = iterator.size_hint();
+        let mut stream_map = Self::with_capacity(lower_bound);
+
+        for (key, value) in iterator {
+            stream_map.insert(key, value);
+        }
+
+        stream_map
+    }
+}
+
+impl<K, V> Extend<(K, V)> for StreamMap<K, V> {
+    fn extend<T>(&mut self, iter: T)
+    where
+        T: IntoIterator<Item = (K, V)>,
+    {
+        self.entries.extend(iter);
+    }
+}
+
 mod rand {
     use std::cell::Cell;
 

tokio-stream/src/wrappers.rs

@@ -1,13 +1,4 @@
 //! Wrappers for Tokio types that implement `Stream`.
-//!
-#![cfg_attr(
-    unix,
-    doc = "You are viewing documentation built under unix. To view windows-specific wrappers, change to the `x86_64-pc-windows-msvc` platform."
-)]
-#![cfg_attr(
-    windows,
-    doc = "You are viewing documentation built under windows. To view unix-specific wrappers, change to the `x86_64-unknown-linux-gnu` platform."
-)]
 
 /// Error types for the wrappers.
 pub mod errors {
@@ -36,9 +27,9 @@ cfg_signal! {
     #[cfg(unix)]
     pub use signal_unix::SignalStream;
 
-    #[cfg(windows)]
+    #[cfg(any(windows, docsrs))]
     mod signal_windows;
-    #[cfg(windows)]
+    #[cfg(any(windows, docsrs))]
     pub use signal_windows::{CtrlCStream, CtrlBreakStream};
 }
 

tokio-stream/src/wrappers/broadcast.rs

@@ -71,3 +71,9 @@ impl<T> fmt::Debug for BroadcastStream<T> {
         f.debug_struct("BroadcastStream").finish()
     }
 }
+
+impl<T: 'static + Clone + Send> From<Receiver<T>> for BroadcastStream<T> {
+    fn from(recv: Receiver<T>) -> Self {
+        Self::new(recv)
+    }
+}

tokio-stream/src/wrappers/mpsc_bounded.rs

@@ -57,3 +57,9 @@ impl<T> AsMut<Receiver<T>> for ReceiverStream<T> {
         &mut self.inner
     }
 }
+
+impl<T> From<Receiver<T>> for ReceiverStream<T> {
+    fn from(recv: Receiver<T>) -> Self {
+        Self::new(recv)
+    }
+}

tokio-stream/src/wrappers/mpsc_unbounded.rs

@@ -51,3 +51,9 @@ impl<T> AsMut<UnboundedReceiver<T>> for UnboundedReceiverStream<T> {
         &mut self.inner
     }
 }
+
+impl<T> From<UnboundedReceiver<T>> for UnboundedReceiverStream<T> {
+    fn from(recv: UnboundedReceiver<T>) -> Self {
+        Self::new(recv)
+    }
+}

tokio-stream/src/wrappers/watch.rs

@@ -11,7 +11,7 @@ use tokio::sync::watch::error::RecvError;
 /// A wrapper around [`tokio::sync::watch::Receiver`] that implements [`Stream`].
 ///
 /// This stream will always start by yielding the current value when the WatchStream is polled,
-/// regardles of whether it was the initial value or sent afterwards.
+/// regardless of whether it was the initial value or sent afterwards.
 ///
 /// # Examples
 ///
@@ -59,7 +59,7 @@ async fn make_future<T: Clone + Send + Sync>(
     (result, rx)
 }
 
-impl<T: 'static + Clone + Unpin + Send + Sync> WatchStream<T> {
+impl<T: 'static + Clone + Send + Sync> WatchStream<T> {
     /// Create a new `WatchStream`.
     pub fn new(rx: Receiver<T>) -> Self {
         Self {
@@ -72,10 +72,10 @@ impl<T: Clone + 'static + Send + Sync> Stream for WatchStream<T> {
     type Item = T;
 
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
-        let (result, rx) = ready!(self.inner.poll(cx));
+        let (result, mut rx) = ready!(self.inner.poll(cx));
         match result {
             Ok(_) => {
-                let received = (*rx.borrow()).clone();
+                let received = (*rx.borrow_and_update()).clone();
                 self.inner.set(make_future(rx));
                 Poll::Ready(Some(received))
             }
@@ -94,3 +94,9 @@ impl<T> fmt::Debug for WatchStream<T> {
         f.debug_struct("WatchStream").finish()
     }
 }
+
+impl<T: 'static + Clone + Send + Sync> From<Receiver<T>> for WatchStream<T> {
+    fn from(recv: Receiver<T>) -> Self {
+        Self::new(recv)
+    }
+}

tokio-stream/tests/async_send_sync.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::diverging_sub_expression)]
+
 use std::rc::Rc;
 
 #[allow(dead_code)]

tokio-stream/tests/stream_chain.rs

@@ -89,12 +89,12 @@ fn size_overflow() {
         }
 
         fn size_hint(&self) -> (usize, Option<usize>) {
-            (usize::max_value(), Some(usize::max_value()))
+            (usize::MAX, Some(usize::MAX))
         }
     }
 
     let m1 = Monster;
     let m2 = Monster;
     let m = m1.chain(m2);
-    assert_eq!(m.size_hint(), (usize::max_value(), None));
+    assert_eq!(m.size_hint(), (usize::MAX, None));
 }

tokio-stream/tests/stream_merge.rs

@@ -72,12 +72,12 @@ fn size_overflow() {
         }
 
         fn size_hint(&self) -> (usize, Option<usize>) {
-            (usize::max_value(), Some(usize::max_value()))
+            (usize::MAX, Some(usize::MAX))
         }
     }
 
     let m1 = Monster;
     let m2 = Monster;
     let m = m1.merge(m2);
-    assert_eq!(m.size_hint(), (usize::max_value(), None));
+    assert_eq!(m.size_hint(), (usize::MAX, None));
 }

tokio-stream/tests/watch.rs

@@ -0,0 +1,29 @@
+#![cfg(feature = "sync")]
+
+use tokio::sync::watch;
+use tokio_stream::wrappers::WatchStream;
+use tokio_stream::StreamExt;
+
+#[tokio::test]
+async fn message_not_twice() {
+    let (tx, rx) = watch::channel("hello");
+
+    let mut counter = 0;
+    let mut stream = WatchStream::new(rx).map(move |payload| {
+        println!("{}", payload);
+        if payload == "goodbye" {
+            counter += 1;
+        }
+        if counter >= 2 {
+            panic!("too many goodbyes");
+        }
+    });
+
+    let task = tokio::spawn(async move { while stream.next().await.is_some() {} });
+
+    // Send goodbye just once
+    tx.send("goodbye").unwrap();
+
+    drop(tx);
+    task.await.unwrap();
+}

tokio-test/CHANGELOG.md

@@ -1,3 +1,9 @@
+# 0.4.2 (May 14, 2021)
+
+- test: add `assert_elapsed!` macro ([#3728])
+
+[#3728]: https://github.com/tokio-rs/tokio/pull/3728
+
 # 0.4.1 (March 10, 2021)
 
 - Fix `io::Mock` to be `Send` and `Sync` ([#3594])

tokio-test/Cargo.toml

@@ -2,17 +2,15 @@
 name = "tokio-test"
 # When releasing to crates.io:
 # - Remove path dependencies
-# - Update doc url
-#   - Cargo.toml
 # - Update CHANGELOG.md.
 # - Create "tokio-test-0.4.x" git tag.
-version = "0.4.1"
+version = "0.4.2"
 edition = "2018"
+rust-version = "1.46"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
-documentation = "https://docs.rs/tokio-test/0.4.1/tokio_test"
 description = """
 Testing utilities for Tokio- and futures-based code
 """
@@ -20,7 +18,7 @@ categories = ["asynchronous", "testing"]
 
 [dependencies]
 tokio = { version = "1.2.0", path = "../tokio", features = ["rt", "sync", "time", "test-util"] }
-tokio-stream = { version = "0.1", path = "../tokio-stream" }
+tokio-stream = { version = "0.1.1", path = "../tokio-stream" }
 async-stream = "0.3"
 
 bytes = "1.0.0"

tokio-test/LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2021 Tokio Contributors
+Copyright (c) 2022 Tokio Contributors
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated

tokio-test/src/lib.rs

@@ -4,13 +4,12 @@
     rust_2018_idioms,
     unreachable_pub
 )]
-#![cfg_attr(docsrs, deny(broken_intra_doc_links))]
 #![doc(test(
     no_crate_inject,
     attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))
 ))]
 
-//! Tokio and Futures based testing utilites
+//! Tokio and Futures based testing utilities
 
 pub mod io;
 

tokio-test/src/task.rs

@@ -180,7 +180,7 @@ impl ThreadWaker {
         }
     }
 
-    /// Clears any previously received wakes, avoiding potential spurrious
+    /// Clears any previously received wakes, avoiding potential spurious
     /// wake notifications. This should only be called immediately before running the
     /// task.
     fn clear(&self) {

tokio-util/CHANGELOG.md

@@ -1,3 +1,49 @@
+# 0.6.9 (October 29, 2021)
+
+### Added
+
+- codec: implement `Clone` for `LengthDelimitedCodec` ([#4089])
+- io: add `SyncIoBridge`  ([#4146])
+
+### Fixed
+
+- time: update deadline on removal in `DelayQueue` ([#4178])
+- codec: Update stream impl for Framed to return None after Err ([#4166])
+
+[#4089]: https://github.com/tokio-rs/tokio/pull/4089
+[#4146]: https://github.com/tokio-rs/tokio/pull/4146
+[#4166]: https://github.com/tokio-rs/tokio/pull/4166
+[#4178]: https://github.com/tokio-rs/tokio/pull/4178
+
+# 0.6.8 (September 3, 2021)
+
+### Added
+
+- sync: add drop guard for `CancellationToken` ([#3839])
+- compact: added `AsyncSeek` compat ([#4078])
+- time: expose `Key` used in `DelayQueue`'s `Expired` ([#4081])
+- io: add `with_capacity` to `ReaderStream` ([#4086])
+
+### Fixed
+
+- codec: remove unnecessary `doc(cfg(...))` ([#3989])
+
+[#3839]: https://github.com/tokio-rs/tokio/pull/3839
+[#4078]: https://github.com/tokio-rs/tokio/pull/4078
+[#4081]: https://github.com/tokio-rs/tokio/pull/4081
+[#4086]: https://github.com/tokio-rs/tokio/pull/4086
+[#3989]: https://github.com/tokio-rs/tokio/pull/3989
+
+# 0.6.7 (May 14, 2021)
+
+### Added
+
+- udp: make `UdpFramed` take `Borrow<UdpSocket>` ([#3451])
+- compat: implement `AsRawFd`/`AsRawHandle` for `Compat<T>` ([#3765])
+
+[#3451]: https://github.com/tokio-rs/tokio/pull/3451
+[#3765]: https://github.com/tokio-rs/tokio/pull/3765
+
 # 0.6.6 (April 12, 2021)
 
 ### Added

tokio-util/Cargo.toml

@@ -2,35 +2,35 @@
 name = "tokio-util"
 # When releasing to crates.io:
 # - Remove path dependencies
-# - Update doc url
-#   - Cargo.toml
 # - Update CHANGELOG.md.
-# - Create "tokio-util-0.6.x" git tag.
-version = "0.6.6"
+# - Create "tokio-util-0.7.x" git tag.
+version = "0.7.0"
 edition = "2018"
+rust-version = "1.46"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
-documentation = "https://docs.rs/tokio-util/0.6.6/tokio_util"
 description = """
 Additional utilities for working with Tokio.
 """
 categories = ["asynchronous"]
+publish = false
 
 [features]
 # No features on by default
 default = []
 
 # Shorthand for enabling everything
-full = ["codec", "compat", "io", "time", "net", "rt"]
+full = ["codec", "compat", "io-util", "time", "net", "rt"]
 
 net = ["tokio/net"]
 compat = ["futures-io",]
 codec = []
 time = ["tokio/time","slab"]
 io = []
-rt = ["tokio/rt"]
+io-util = ["io", "tokio/rt", "tokio/io-util"]
+rt = ["tokio/rt", "tokio/sync", "futures-util"]
 
 __docs_rs = ["futures-util"]
 
@@ -44,7 +44,7 @@ futures-io = { version = "0.3.0", optional = true }
 futures-util = { version = "0.3.0", optional = true }
 log = "0.4"
 pin-project-lite = "0.2.0"
-slab = { version = "0.4.1", optional = true } # Backs `DelayQueue`
+slab = { version = "0.4.4", optional = true } # Backs `DelayQueue`
 
 [dev-dependencies]
 tokio = { version = "1.0.0", path = "../tokio", features = ["full"] }

tokio-util/LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2021 Tokio Contributors
+Copyright (c) 2022 Tokio Contributors
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated

tokio-util/README.md

@@ -1,6 +1,6 @@
 # tokio-util
 
-Utilities for encoding and decoding frames.
+Utilities for working with Tokio.
 
 ## License
 

tokio-util/src/cfg.rs

@@ -38,6 +38,18 @@ macro_rules! cfg_io {
     }
 }
 
+cfg_io! {
+    macro_rules! cfg_io_util {
+        ($($item:item)*) => {
+            $(
+                #[cfg(feature = "io-util")]
+                #[cfg_attr(docsrs, doc(cfg(feature = "io-util")))]
+                $item
+            )*
+        }
+    }
+}
+
 macro_rules! cfg_rt {
     ($($item:item)*) => {
         $(

tokio-util/src/codec/any_delimiter_codec.rs

@@ -234,7 +234,7 @@ impl Default for AnyDelimiterCodec {
     }
 }
 
-/// An error occured while encoding or decoding a chunk.
+/// An error occurred while encoding or decoding a chunk.
 #[derive(Debug)]
 pub enum AnyDelimiterCodecError {
     /// The maximum chunk length was exceeded.

tokio-util/src/codec/decoder.rs

@@ -28,7 +28,7 @@ use std::io;
 /// It is up to the Decoder to keep track of a restart after an EOF,
 /// and to decide how to handle such an event by, for example,
 /// allowing frames to cross EOF boundaries, re-emitting opening frames, or
-/// reseting the entire internal state.
+/// resetting the entire internal state.
 ///
 /// [`Framed`]: crate::codec::Framed
 /// [`FramedRead`]: crate::codec::FramedRead

tokio-util/src/codec/framed.rs

@@ -106,6 +106,7 @@ where
                         eof: false,
                         is_readable: false,
                         buffer: BytesMut::with_capacity(capacity),
+                        has_errored: false,
                     },
                     write: WriteFrame::default(),
                 },
@@ -203,6 +204,35 @@ impl<T, U> Framed<T, U> {
         &mut self.inner.codec
     }
 
+    /// Maps the codec `U` to `C`, preserving the read and write buffers
+    /// wrapped by `Framed`.
+    ///
+    /// Note that care should be taken to not tamper with the underlying codec
+    /// as it may corrupt the stream of frames otherwise being worked with.
+    pub fn map_codec<C, F>(self, map: F) -> Framed<T, C>
+    where
+        F: FnOnce(U) -> C,
+    {
+        // This could be potentially simplified once rust-lang/rust#86555 hits stable
+        let parts = self.into_parts();
+        Framed::from_parts(FramedParts {
+            io: parts.io,
+            codec: map(parts.codec),
+            read_buf: parts.read_buf,
+            write_buf: parts.write_buf,
+            _priv: (),
+        })
+    }
+
+    /// Returns a mutable reference to the underlying codec wrapped by
+    /// `Framed`.
+    ///
+    /// Note that care should be taken to not tamper with the underlying codec
+    /// as it may corrupt the stream of frames otherwise being worked with.
+    pub fn codec_pin_mut(self: Pin<&mut Self>) -> &mut U {
+        self.project().inner.project().codec
+    }
+
     /// Returns a reference to the read buffer.
     pub fn read_buffer(&self) -> &BytesMut {
         &self.inner.state.read.buffer

tokio-util/src/codec/framed_impl.rs

@@ -27,10 +27,12 @@ pin_project! {
 const INITIAL_CAPACITY: usize = 8 * 1024;
 const BACKPRESSURE_BOUNDARY: usize = INITIAL_CAPACITY;
 
+#[derive(Debug)]
 pub(crate) struct ReadFrame {
     pub(crate) eof: bool,
     pub(crate) is_readable: bool,
     pub(crate) buffer: BytesMut,
+    pub(crate) has_errored: bool,
 }
 
 pub(crate) struct WriteFrame {
@@ -49,6 +51,7 @@ impl Default for ReadFrame {
             eof: false,
             is_readable: false,
             buffer: BytesMut::with_capacity(INITIAL_CAPACITY),
+            has_errored: false,
         }
     }
 }
@@ -72,6 +75,7 @@ impl From<BytesMut> for ReadFrame {
             buffer,
             is_readable: size > 0,
             eof: false,
+            has_errored: false,
         }
     }
 }
@@ -124,48 +128,64 @@ where
         // to a combination of the `is_readable` and `eof` flags. States persist across
         // loop entries and most state transitions occur with a return.
         //
-        // The intitial state is `reading`.
+        // The initial state is `reading`.
         //
-        // | state   | eof   | is_readable |
-        // |---------|-------|-------------|
-        // | reading | false | false       |
-        // | framing | false | true        |
-        // | pausing | true  | true        |
-        // | paused  | true  | false       |
-        //
-        //                                 `decode_eof`
-        //                                 returns `Some`             read 0 bytes
-        //                                   │       │                 │      │
-        //                                   │       ▼                 │      ▼
-        //                                   ┌───────┐ `decode_eof`    ┌──────┐
-        //                 ┌──read 0 bytes──▶│pausing│─returns `None`─▶│paused│──┐
-        //                 │                 └───────┘                 └──────┘  │
-        // pending read┐   │                     ┌──────┐                  │  ▲  │
-        //      │      │   │                     │      │                  │  │  │
-        //      │      ▼   │                     │  `decode` returns `Some`│ pending read
-        //      │  ╔═══════╗                 ┌───────┐◀─┘                  │
-        //      └──║reading║─read n>0 bytes─▶│framing│                     │
-        //         ╚═══════╝                 └───────┘◀──────read n>0 bytes┘
-        //             ▲                         │
-        //             │                         │
-        //             └─`decode` returns `None`─┘
+        // | state   | eof   | is_readable | has_errored |
+        // |---------|-------|-------------|-------------|
+        // | reading | false | false       | false       |
+        // | framing | false | true        | false       |
+        // | pausing | true  | true        | false       |
+        // | paused  | true  | false       | false       |
+        // | errored | <any> | <any>       | true        |
+        //                                                       `decode_eof` returns Err
+        //                                          ┌────────────────────────────────────────────────────────┐
+        //                   `decode_eof` returns   │                                                        │
+        //                             `Ok(Some)`   │                                                        │
+        //                                 ┌─────┐  │     `decode_eof` returns               After returning │
+        //                Read 0 bytes     ├─────▼──┴┐    `Ok(None)`          ┌────────┐ ◄───┐ `None`    ┌───▼─────┐
+        //               ┌────────────────►│ Pausing ├───────────────────────►│ Paused ├─┐   └───────────┤ Errored │
+        //               │                 └─────────┘                        └─┬──▲───┘ │               └───▲───▲─┘
+        // Pending read  │                                                      │  │     │                   │   │
+        //     ┌──────┐  │            `decode` returns `Some`                   │  └─────┘                   │   │
+        //     │      │  │                   ┌──────┐                           │  Pending                   │   │
+        //     │ ┌────▼──┴─┐ Read n>0 bytes ┌┴──────▼─┐     read n>0 bytes      │  read                      │   │
+        //     └─┤ Reading ├───────────────►│ Framing │◄────────────────────────┘                            │   │
+        //       └──┬─▲────┘                └─────┬──┬┘                                                      │   │
+        //          │ │                           │  │                 `decode` returns Err                  │   │
+        //          │ └───decode` returns `None`──┘  └───────────────────────────────────────────────────────┘   │
+        //          │                             read returns Err                                               │
+        //          └────────────────────────────────────────────────────────────────────────────────────────────┘
         loop {
+            // Return `None` if we have encountered an error from the underlying decoder
+            // See: https://github.com/tokio-rs/tokio/issues/3976
+            if state.has_errored {
+                // preparing has_errored -> paused
+                trace!("Returning None and setting paused");
+                state.is_readable = false;
+                state.has_errored = false;
+                return Poll::Ready(None);
+            }
+
             // Repeatedly call `decode` or `decode_eof` while the buffer is "readable",
             // i.e. it _might_ contain data consumable as a frame or closing frame.
             // Both signal that there is no such data by returning `None`.
             //
             // If `decode` couldn't read a frame and the upstream source has returned eof,
-            // `decode_eof` will attemp to decode the remaining bytes as closing frames.
+            // `decode_eof` will attempt to decode the remaining bytes as closing frames.
             //
             // If the underlying AsyncRead is resumable, we may continue after an EOF,
-            // but must finish emmiting all of it's associated `decode_eof` frames.
+            // but must finish emitting all of it's associated `decode_eof` frames.
             // Furthermore, we don't want to emit any `decode_eof` frames on retried
             // reads after an EOF unless we've actually read more data.
             if state.is_readable {
                 // pausing or framing
                 if state.eof {
                     // pausing
-                    let frame = pinned.codec.decode_eof(&mut state.buffer)?;
+                    let frame = pinned.codec.decode_eof(&mut state.buffer).map_err(|err| {
+                        trace!("Got an error, going to errored state");
+                        state.has_errored = true;
+                        err
+                    })?;
                     if frame.is_none() {
                         state.is_readable = false; // prepare pausing -> paused
                     }
@@ -176,7 +196,11 @@ where
                 // framing
                 trace!("attempting to decode a frame");
 
-                if let Some(frame) = pinned.codec.decode(&mut state.buffer)? {
+                if let Some(frame) = pinned.codec.decode(&mut state.buffer).map_err(|op| {
+                    trace!("Got an error, going to errored state");
+                    state.has_errored = true;
+                    op
+                })? {
                     trace!("frame decoded from buffer");
                     // implicit framing -> framing
                     return Poll::Ready(Some(Ok(frame)));
@@ -190,7 +214,13 @@ 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);
-            let bytect = match poll_read_buf(pinned.inner.as_mut(), cx, &mut state.buffer)? {
+            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");
+                    state.has_errored = true;
+                    err
+                },
+            )? {
                 Poll::Ready(ct) => ct,
                 // implicit reading -> reading or implicit paused -> paused
                 Poll::Pending => return Poll::Pending,

tokio-util/src/codec/framed_read.rs

@@ -51,6 +51,7 @@ where
                     eof: false,
                     is_readable: false,
                     buffer: BytesMut::with_capacity(capacity),
+                    has_errored: false,
                 },
             },
         }
@@ -107,6 +108,32 @@ impl<T, D> FramedRead<T, D> {
         &mut self.inner.codec
     }
 
+    /// Maps the decoder `D` to `C`, preserving the read buffer
+    /// wrapped by `Framed`.
+    pub fn map_decoder<C, F>(self, map: F) -> FramedRead<T, C>
+    where
+        F: FnOnce(D) -> C,
+    {
+        // This could be potentially simplified once rust-lang/rust#86555 hits stable
+        let FramedImpl {
+            inner,
+            state,
+            codec,
+        } = self.inner;
+        FramedRead {
+            inner: FramedImpl {
+                inner,
+                state,
+                codec: map(codec),
+            },
+        }
+    }
+
+    /// Returns a mutable reference to the underlying decoder.
+    pub fn decoder_pin_mut(self: Pin<&mut Self>) -> &mut D {
+        self.project().inner.project().codec
+    }
+
     /// Returns a reference to the read buffer.
     pub fn read_buffer(&self) -> &BytesMut {
         &self.inner.state.buffer

tokio-util/src/codec/framed_write.rs

@@ -88,6 +88,32 @@ impl<T, E> FramedWrite<T, E> {
         &mut self.inner.codec
     }
 
+    /// Maps the encoder `E` to `C`, preserving the write buffer
+    /// wrapped by `Framed`.
+    pub fn map_encoder<C, F>(self, map: F) -> FramedWrite<T, C>
+    where
+        F: FnOnce(E) -> C,
+    {
+        // This could be potentially simplified once rust-lang/rust#86555 hits stable
+        let FramedImpl {
+            inner,
+            state,
+            codec,
+        } = self.inner;
+        FramedWrite {
+            inner: FramedImpl {
+                inner,
+                state,
+                codec: map(codec),
+            },
+        }
+    }
+
+    /// Returns a mutable reference to the underlying encoder.
+    pub fn encoder_pin_mut(self: Pin<&mut Self>) -> &mut E {
+        self.project().inner.project().codec
+    }
+
     /// Returns a reference to the write buffer.
     pub fn write_buffer(&self) -> &BytesMut {
         &self.inner.state.buffer

tokio-util/src/codec/length_delimited.rs

@@ -421,7 +421,7 @@ pub struct LengthDelimitedCodecError {
 /// See [module level] documentation for more detail.
 ///
 /// [module level]: index.html
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct LengthDelimitedCodec {
     // Configuration values
     builder: Builder,
@@ -486,7 +486,7 @@ impl LengthDelimitedCodec {
             // Skip the required bytes
             src.advance(self.builder.length_field_offset);
 
-            // match endianess
+            // match endianness
             let n = if self.builder.length_field_is_big_endian {
                 src.get_uint(field_len)
             } else {
@@ -746,7 +746,7 @@ impl Builder {
         }
     }
 
-    /// Sets the max frame length
+    /// Sets the max frame length in bytes
     ///
     /// This configuration option applies to both encoding and decoding. The
     /// default value is 8MB.
@@ -767,7 +767,7 @@ impl Builder {
     ///
     /// # fn bind_read<T: AsyncRead>(io: T) {
     /// LengthDelimitedCodec::builder()
-    ///     .max_frame_length(8 * 1024)
+    ///     .max_frame_length(8 * 1024 * 1024)
     ///     .new_read(io);
     /// # }
     /// # pub fn main() {}

tokio-util/src/codec/lines_codec.rs

@@ -203,12 +203,12 @@ impl Default for LinesCodec {
     }
 }
 
-/// An error occured while encoding or decoding a line.
+/// An error occurred while encoding or decoding a line.
 #[derive(Debug)]
 pub enum LinesCodecError {
     /// The maximum line length was exceeded.
     MaxLineLengthExceeded,
-    /// An IO error occured.
+    /// An IO error occurred.
     Io(io::Error),
 }
 

tokio-util/src/compat.rs

@@ -13,6 +13,7 @@ pin_project! {
     pub struct Compat<T> {
         #[pin]
         inner: T,
+        seek_pos: Option<io::SeekFrom>,
     }
 }
 
@@ -80,7 +81,10 @@ impl<T: tokio::io::AsyncWrite> TokioAsyncWriteCompatExt for T {}
 
 impl<T> Compat<T> {
     fn new(inner: T) -> Self {
-        Self { inner }
+        Self {
+            inner,
+            seek_pos: None,
+        }
     }
 
     /// Get a reference to the `Future`, `Stream`, `AsyncRead`, or `AsyncWrite` object
@@ -216,6 +220,45 @@ where
     }
 }
 
+impl<T: tokio::io::AsyncSeek> futures_io::AsyncSeek for Compat<T> {
+    fn poll_seek(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        pos: io::SeekFrom,
+    ) -> Poll<io::Result<u64>> {
+        if self.seek_pos != Some(pos) {
+            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))
+    }
+}
+
+impl<T: futures_io::AsyncSeek> tokio::io::AsyncSeek for Compat<T> {
+    fn start_seek(mut self: Pin<&mut Self>, pos: io::SeekFrom) -> io::Result<()> {
+        *self.as_mut().project().seek_pos = Some(pos);
+        Ok(())
+    }
+
+    fn poll_complete(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<u64>> {
+        let pos = match self.seek_pos {
+            None => {
+                // tokio 1.x AsyncSeek recommends calling poll_complete before start_seek.
+                // We don't have to guarantee that the value returned by
+                // poll_complete called without start_seek is correct,
+                // so we'll return 0.
+                return Poll::Ready(Ok(0));
+            }
+            Some(pos) => pos,
+        };
+        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))
+    }
+}
+
 #[cfg(unix)]
 impl<T: std::os::unix::io::AsRawFd> std::os::unix::io::AsRawFd for Compat<T> {
     fn as_raw_fd(&self) -> std::os::unix::io::RawFd {

tokio-util/src/either.rs

@@ -67,7 +67,7 @@ pub enum Either<L, R> {
 }
 
 /// A small helper macro which reduces amount of boilerplate in the actual trait method implementation.
-/// It takes an invokation of method as an argument (e.g. `self.poll(cx)`), and redirects it to either
+/// It takes an invocation of method as an argument (e.g. `self.poll(cx)`), and redirects it to either
 /// enum variant held in `self`.
 macro_rules! delegate_call {
     ($self:ident.$method:ident($($args:ident),+)) => {

tokio-util/src/io/mod.rs

@@ -1,14 +1,22 @@
 //! Helpers for IO related tasks.
 //!
-//! These types are often used in combination with hyper or reqwest, as they
+//! The stream types are often used in combination with hyper or reqwest, as they
 //! allow converting between a hyper [`Body`] and [`AsyncRead`].
 //!
+//! The [`SyncIoBridge`] type converts from the world of async I/O
+//! to synchronous I/O; this may often come up when using synchronous APIs
+//! inside [`tokio::task::spawn_blocking`].
+//!
 //! [`Body`]: https://docs.rs/hyper/0.13/hyper/struct.Body.html
 //! [`AsyncRead`]: tokio::io::AsyncRead
 
 mod read_buf;
 mod reader_stream;
 mod stream_reader;
+cfg_io_util! {
+    mod sync_bridge;
+    pub use self::sync_bridge::SyncIoBridge;
+}
 
 pub use self::read_buf::read_buf;
 pub use self::reader_stream::ReaderStream;

tokio-util/src/io/reader_stream.rs

@@ -5,7 +5,7 @@ use std::pin::Pin;
 use std::task::{Context, Poll};
 use tokio::io::AsyncRead;
 
-const CAPACITY: usize = 4096;
+const DEFAULT_CAPACITY: usize = 4096;
 
 pin_project! {
     /// Convert an [`AsyncRead`] into a [`Stream`] of byte chunks.
@@ -50,6 +50,7 @@ pin_project! {
         reader: Option<R>,
         // Working buffer, used to optimize allocations.
         buf: BytesMut,
+        capacity: usize,
     }
 }
 
@@ -63,6 +64,21 @@ impl<R: AsyncRead> ReaderStream<R> {
         ReaderStream {
             reader: Some(reader),
             buf: BytesMut::new(),
+            capacity: DEFAULT_CAPACITY,
+        }
+    }
+
+    /// Convert an [`AsyncRead`] into a [`Stream`] with item type
+    /// `Result<Bytes, std::io::Error>`,
+    /// with a specific read buffer initial capacity.
+    ///
+    /// [`AsyncRead`]: tokio::io::AsyncRead
+    /// [`Stream`]: futures_core::Stream
+    pub fn with_capacity(reader: R, capacity: usize) -> Self {
+        ReaderStream {
+            reader: Some(reader),
+            buf: BytesMut::with_capacity(capacity),
+            capacity,
         }
     }
 }
@@ -80,7 +96,7 @@ impl<R: AsyncRead> Stream for ReaderStream<R> {
         };
 
         if this.buf.capacity() == 0 {
-            this.buf.reserve(CAPACITY);
+            this.buf.reserve(*this.capacity);
         }
 
         match poll_read_buf(reader, cx, &mut this.buf) {

tokio-util/src/io/sync_bridge.rs

@@ -0,0 +1,103 @@
+use std::io::{Read, Write};
+use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
+
+/// Use a [`tokio::io::AsyncRead`] synchronously as a [`std::io::Read`] or
+/// a [`tokio::io::AsyncWrite`] as a [`std::io::Write`].
+#[derive(Debug)]
+pub struct SyncIoBridge<T> {
+    src: T,
+    rt: tokio::runtime::Handle,
+}
+
+impl<T: AsyncRead + Unpin> Read for SyncIoBridge<T> {
+    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+        let src = &mut self.src;
+        self.rt.block_on(AsyncReadExt::read(src, buf))
+    }
+
+    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> std::io::Result<usize> {
+        let src = &mut self.src;
+        self.rt.block_on(src.read_to_end(buf))
+    }
+
+    fn read_to_string(&mut self, buf: &mut String) -> std::io::Result<usize> {
+        let src = &mut self.src;
+        self.rt.block_on(src.read_to_string(buf))
+    }
+
+    fn read_exact(&mut self, buf: &mut [u8]) -> std::io::Result<()> {
+        let src = &mut self.src;
+        // The AsyncRead trait returns the count, synchronous doesn't.
+        let _n = self.rt.block_on(src.read_exact(buf))?;
+        Ok(())
+    }
+}
+
+impl<T: AsyncWrite + Unpin> Write for SyncIoBridge<T> {
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        let src = &mut self.src;
+        self.rt.block_on(src.write(buf))
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        let src = &mut self.src;
+        self.rt.block_on(src.flush())
+    }
+
+    fn write_all(&mut self, buf: &[u8]) -> std::io::Result<()> {
+        let src = &mut self.src;
+        self.rt.block_on(src.write_all(buf))
+    }
+
+    fn write_vectored(&mut self, bufs: &[std::io::IoSlice<'_>]) -> std::io::Result<usize> {
+        let src = &mut self.src;
+        self.rt.block_on(src.write_vectored(bufs))
+    }
+}
+
+// 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> {
+    /// Determines if the underlying [`tokio::io::AsyncWrite`] target supports efficient vectored writes.
+    ///
+    /// See [`tokio::io::AsyncWrite::is_write_vectored`].
+    pub fn is_write_vectored(&self) -> bool {
+        self.src.is_write_vectored()
+    }
+}
+
+impl<T: Unpin> SyncIoBridge<T> {
+    /// Use a [`tokio::io::AsyncRead`] synchronously as a [`std::io::Read`] or
+    /// a [`tokio::io::AsyncWrite`] as a [`std::io::Write`].
+    ///
+    /// When this struct is created, it captures a handle to the current thread's runtime with [`tokio::runtime::Handle::current`].
+    /// It is hence OK to move this struct into a separate thread outside the runtime, as created
+    /// by e.g. [`tokio::task::spawn_blocking`].
+    ///
+    /// Stated even more strongly: to make use of this bridge, you *must* move
+    /// it into a separate thread outside the runtime.  The synchronous I/O will use the
+    /// underlying handle to block on the backing asynchronous source, via
+    /// [`tokio::runtime::Handle::block_on`].  As noted in the documentation for that
+    /// function, an attempt to `block_on` from an asynchronous execution context
+    /// will panic.
+    ///
+    /// # Wrapping `!Unpin` types
+    ///
+    /// Use e.g. `SyncIoBridge::new(Box::pin(src))`.
+    ///
+    /// # Panic
+    ///
+    /// This will panic if called outside the context of a Tokio runtime.
+    pub fn new(src: T) -> Self {
+        Self::new_with_handle(src, tokio::runtime::Handle::current())
+    }
+
+    /// Use a [`tokio::io::AsyncRead`] synchronously as a [`std::io::Read`] or
+    /// a [`tokio::io::AsyncWrite`] as a [`std::io::Write`].
+    ///
+    /// This is the same as [`SyncIoBridge::new`], but allows passing an arbitrary handle and hence may
+    /// be initially invoked outside of an asynchronous context.
+    pub fn new_with_handle(src: T, rt: tokio::runtime::Handle) -> Self {
+        Self { src, rt }
+    }
+}

tokio-util/src/lib.rs

@@ -5,7 +5,6 @@
     rust_2018_idioms,
     unreachable_pub
 )]
-#![cfg_attr(docsrs, deny(broken_intra_doc_links))]
 #![doc(test(
     no_crate_inject,
     attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))
@@ -31,6 +30,7 @@ cfg_codec! {
 
 cfg_net! {
     pub mod udp;
+    pub mod net;
 }
 
 cfg_compat! {
@@ -43,6 +43,7 @@ cfg_io! {
 
 cfg_rt! {
     pub mod context;
+    pub mod task;
 }
 
 cfg_time! {

tokio-util/src/net/mod.rs

@@ -0,0 +1,97 @@
+//! TCP/UDP/Unix helpers for tokio.
+
+use crate::either::Either;
+use std::future::Future;
+use std::io::Result;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+#[cfg(unix)]
+pub mod unix;
+
+/// A trait for a listener: `TcpListener` and `UnixListener`.
+pub trait Listener {
+    /// The stream's type of this listener.
+    type Io: tokio::io::AsyncRead + tokio::io::AsyncWrite;
+    /// The socket address type of this listener.
+    type Addr;
+
+    /// Polls to accept a new incoming connection to this listener.
+    fn poll_accept(&mut self, cx: &mut Context<'_>) -> Poll<Result<(Self::Io, Self::Addr)>>;
+
+    /// Accepts a new incoming connection from this listener.
+    fn accept(&mut self) -> ListenerAcceptFut<'_, Self>
+    where
+        Self: Sized,
+    {
+        ListenerAcceptFut { listener: self }
+    }
+
+    /// Returns the local address that this listener is bound to.
+    fn local_addr(&self) -> Result<Self::Addr>;
+}
+
+impl Listener for tokio::net::TcpListener {
+    type Io = tokio::net::TcpStream;
+    type Addr = std::net::SocketAddr;
+
+    fn poll_accept(&mut self, cx: &mut Context<'_>) -> Poll<Result<(Self::Io, Self::Addr)>> {
+        Self::poll_accept(self, cx)
+    }
+
+    fn local_addr(&self) -> Result<Self::Addr> {
+        self.local_addr().map(Into::into)
+    }
+}
+
+/// Future for accepting a new connection from a listener.
+#[derive(Debug)]
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct ListenerAcceptFut<'a, L> {
+    listener: &'a mut L,
+}
+
+impl<'a, L> Future for ListenerAcceptFut<'a, L>
+where
+    L: Listener,
+{
+    type Output = Result<(L::Io, L::Addr)>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        self.listener.poll_accept(cx)
+    }
+}
+
+impl<L, R> Either<L, R>
+where
+    L: Listener,
+    R: Listener,
+{
+    /// Accepts a new incoming connection from this listener.
+    pub async fn accept(&mut self) -> Result<Either<(L::Io, L::Addr), (R::Io, R::Addr)>> {
+        match self {
+            Either::Left(listener) => {
+                let (stream, addr) = listener.accept().await?;
+                Ok(Either::Left((stream, addr)))
+            }
+            Either::Right(listener) => {
+                let (stream, addr) = listener.accept().await?;
+                Ok(Either::Right((stream, addr)))
+            }
+        }
+    }
+
+    /// Returns the local address that this listener is bound to.
+    pub fn local_addr(&self) -> Result<Either<L::Addr, R::Addr>> {
+        match self {
+            Either::Left(listener) => {
+                let addr = listener.local_addr()?;
+                Ok(Either::Left(addr))
+            }
+            Either::Right(listener) => {
+                let addr = listener.local_addr()?;
+                Ok(Either::Right(addr))
+            }
+        }
+    }
+}

tokio-util/src/net/unix/mod.rs

@@ -0,0 +1,18 @@
+//! Unix domain socket helpers.
+
+use super::Listener;
+use std::io::Result;
+use std::task::{Context, Poll};
+
+impl Listener for tokio::net::UnixListener {
+    type Io = tokio::net::UnixStream;
+    type Addr = tokio::net::unix::SocketAddr;
+
+    fn poll_accept(&mut self, cx: &mut Context<'_>) -> Poll<Result<(Self::Io, Self::Addr)>> {
+        Self::poll_accept(self, cx)
+    }
+
+    fn local_addr(&self) -> Result<Self::Addr> {
+        self.local_addr().map(Into::into)
+    }
+}

tokio-util/src/sync/cancellation_token.rs

@@ -1,5 +1,6 @@
 //! An asynchronously awaitable `CancellationToken`.
 //! The token allows to signal a cancellation request to one or more tasks.
+pub(crate) mod guard;
 
 use crate::loom::sync::atomic::AtomicUsize;
 use crate::loom::sync::Mutex;
@@ -11,6 +12,8 @@ use core::ptr::NonNull;
 use core::sync::atomic::Ordering;
 use core::task::{Context, Poll, Waker};
 
+use guard::DropGuard;
+
 /// A token which can be used to signal a cancellation request to one or more
 /// tasks.
 ///
@@ -275,6 +278,14 @@ impl CancellationToken {
         }
     }
 
+    /// Creates a `DropGuard` for this token.
+    ///
+    /// Returned guard will cancel this token (and all its children) on drop
+    /// unless disarmed.
+    pub fn drop_guard(self) -> DropGuard {
+        DropGuard { inner: Some(self) }
+    }
+
     unsafe fn register(
         &self,
         wait_node: &mut ListNode<WaitQueueEntry>,
@@ -764,8 +775,8 @@ impl CancellationTokenState {
             return Poll::Ready(());
         }
 
-        // So far the token is not cancelled. However it could be cancelld before
-        // we get the chance to store the `Waker`. Therfore we need to check
+        // So far the token is not cancelled. However it could be cancelled before
+        // we get the chance to store the `Waker`. Therefore we need to check
         // for cancellation again inside the mutex.
         let mut guard = self.synchronized.lock().unwrap();
         if guard.is_cancelled {

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

@@ -0,0 +1,27 @@
+use crate::sync::CancellationToken;
+
+/// A wrapper for cancellation token which automatically cancels
+/// it on drop. It is created using `drop_guard` method on the `CancellationToken`.
+#[derive(Debug)]
+pub struct DropGuard {
+    pub(super) inner: Option<CancellationToken>,
+}
+
+impl DropGuard {
+    /// Returns stored cancellation token and removes this drop guard instance
+    /// (i.e. it will no longer cancel token). Other guards for this token
+    /// are not affected.
+    pub fn disarm(mut self) -> CancellationToken {
+        self.inner
+            .take()
+            .expect("`inner` can be only None in a destructor")
+    }
+}
+
+impl Drop for DropGuard {
+    fn drop(&mut self) {
+        if let Some(inner) = &self.inner {
+            inner.cancel();
+        }
+    }
+}

tokio-util/src/sync/intrusive_double_linked_list.rs

@@ -222,7 +222,7 @@ impl<T> LinkedList<T> {
         }
     }
 
-    /// Returns whether the linked list doesn not contain any node
+    /// Returns whether the linked list does not contain any node
     pub fn is_empty(&self) -> bool {
         if self.head.is_some() {
             return false;

tokio-util/src/sync/mod.rs

@@ -1,7 +1,7 @@
 //! Synchronization primitives
 
 mod cancellation_token;
-pub use cancellation_token::{CancellationToken, WaitForCancellationFuture};
+pub use cancellation_token::{guard::DropGuard, CancellationToken, WaitForCancellationFuture};
 
 mod intrusive_double_linked_list;
 

tokio-util/src/task/mod.rs

@@ -0,0 +1,4 @@
+//! Extra utilities for spawning tasks
+
+mod spawn_pinned;
+pub use spawn_pinned::LocalPoolHandle;

tokio-util/src/task/spawn_pinned.rs

@@ -0,0 +1,307 @@
+use futures_util::future::{AbortHandle, Abortable};
+use std::fmt;
+use std::fmt::{Debug, Formatter};
+use std::future::Future;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+use tokio::runtime::Builder;
+use tokio::sync::mpsc::{unbounded_channel, UnboundedReceiver, UnboundedSender};
+use tokio::sync::oneshot;
+use tokio::task::{spawn_local, JoinHandle, LocalSet};
+
+/// A handle to a local pool, used for spawning `!Send` tasks.
+#[derive(Clone)]
+pub struct LocalPoolHandle {
+    pool: Arc<LocalPool>,
+}
+
+impl LocalPoolHandle {
+    /// Create a new pool of threads to handle `!Send` tasks. Spawn tasks onto this
+    /// pool via [`LocalPoolHandle::spawn_pinned`].
+    ///
+    /// # Panics
+    /// Panics if the pool size is less than one.
+    pub fn new(pool_size: usize) -> LocalPoolHandle {
+        assert!(pool_size > 0);
+
+        let workers = (0..pool_size)
+            .map(|_| LocalWorkerHandle::new_worker())
+            .collect();
+
+        let pool = Arc::new(LocalPool { workers });
+
+        LocalPoolHandle { pool }
+    }
+
+    /// Spawn a task onto a worker thread and pin it there so it can't be moved
+    /// off of the thread. Note that the future is not [`Send`], but the
+    /// [`FnOnce`] which creates it is.
+    ///
+    /// # Examples
+    /// ```
+    /// use std::rc::Rc;
+    /// use tokio_util::task::LocalPoolHandle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     // Create the local pool
+    ///     let pool = LocalPoolHandle::new(1);
+    ///
+    ///     // Spawn a !Send future onto the pool and await it
+    ///     let output = pool
+    ///         .spawn_pinned(|| {
+    ///             // Rc is !Send + !Sync
+    ///             let local_data = Rc::new("test");
+    ///
+    ///             // This future holds an Rc, so it is !Send
+    ///             async move { local_data.to_string() }
+    ///         })
+    ///         .await
+    ///         .unwrap();
+    ///
+    ///     assert_eq!(output, "test");
+    /// }
+    /// ```
+    pub fn spawn_pinned<F, Fut>(&self, create_task: F) -> JoinHandle<Fut::Output>
+    where
+        F: FnOnce() -> Fut,
+        F: Send + 'static,
+        Fut: Future + 'static,
+        Fut::Output: Send + 'static,
+    {
+        self.pool.spawn_pinned(create_task)
+    }
+}
+
+impl Debug for LocalPoolHandle {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.write_str("LocalPoolHandle")
+    }
+}
+
+struct LocalPool {
+    workers: Vec<LocalWorkerHandle>,
+}
+
+impl LocalPool {
+    /// Spawn a `?Send` future onto a worker
+    fn spawn_pinned<F, Fut>(&self, create_task: F) -> JoinHandle<Fut::Output>
+    where
+        F: FnOnce() -> Fut,
+        F: Send + 'static,
+        Fut: Future + 'static,
+        Fut::Output: Send + 'static,
+    {
+        let (sender, receiver) = oneshot::channel();
+
+        let (worker, job_guard) = self.find_and_incr_least_burdened_worker();
+        let worker_spawner = worker.spawner.clone();
+
+        // Spawn a future onto the worker's runtime so we can immediately return
+        // a join handle.
+        worker.runtime_handle.spawn(async move {
+            // Move the job guard into the task
+            let _job_guard = job_guard;
+
+            // Propagate aborts via Abortable/AbortHandle
+            let (abort_handle, abort_registration) = AbortHandle::new_pair();
+            let _abort_guard = AbortGuard(abort_handle);
+
+            // Inside the future we can't run spawn_local yet because we're not
+            // in the context of a LocalSet. We need to send create_task to the
+            // LocalSet task for spawning.
+            let spawn_task = Box::new(move || {
+                // Once we're in the LocalSet context we can call spawn_local
+                let join_handle =
+                    spawn_local(
+                        async move { Abortable::new(create_task(), abort_registration).await },
+                    );
+
+                // Send the join handle back to the spawner. If sending fails,
+                // we assume the parent task was canceled, so cancel this task
+                // as well.
+                if let Err(join_handle) = sender.send(join_handle) {
+                    join_handle.abort()
+                }
+            });
+
+            // Send the callback to the LocalSet task
+            if let Err(e) = worker_spawner.send(spawn_task) {
+                // Propagate the error as a panic in the join handle.
+                panic!("Failed to send job to worker: {}", e);
+            }
+
+            // Wait for the task's join handle
+            let join_handle = match receiver.await {
+                Ok(handle) => handle,
+                Err(e) => {
+                    // We sent the task successfully, but failed to get its
+                    // join handle... We assume something happened to the worker
+                    // and the task was not spawned. Propagate the error as a
+                    // panic in the join handle.
+                    panic!("Worker failed to send join handle: {}", e);
+                }
+            };
+
+            // Wait for the task to complete
+            let join_result = join_handle.await;
+
+            match join_result {
+                Ok(Ok(output)) => output,
+                Ok(Err(_)) => {
+                    // Pinned task was aborted. But that only happens if this
+                    // task is aborted. So this is an impossible branch.
+                    unreachable!(
+                        "Reaching this branch means this task was previously \
+                         aborted but it continued running anyways"
+                    )
+                }
+                Err(e) => {
+                    if e.is_panic() {
+                        std::panic::resume_unwind(e.into_panic());
+                    } else if e.is_cancelled() {
+                        // No one else should have the join handle, so this is
+                        // unexpected. Forward this error as a panic in the join
+                        // handle.
+                        panic!("spawn_pinned task was canceled: {}", e);
+                    } else {
+                        // Something unknown happened (not a panic or
+                        // cancellation). Forward this error as a panic in the
+                        // join handle.
+                        panic!("spawn_pinned task failed: {}", e);
+                    }
+                }
+            }
+        })
+    }
+
+    /// Find the worker with the least number of tasks, increment its task
+    /// count, and return its handle. Make sure to actually spawn a task on
+    /// the worker so the task count is kept consistent with load.
+    ///
+    /// A job count guard is also returned to ensure the task count gets
+    /// decremented when the job is done.
+    fn find_and_incr_least_burdened_worker(&self) -> (&LocalWorkerHandle, JobCountGuard) {
+        loop {
+            let (worker, task_count) = self
+                .workers
+                .iter()
+                .map(|worker| (worker, worker.task_count.load(Ordering::SeqCst)))
+                .min_by_key(|&(_, count)| count)
+                .expect("There must be more than one worker");
+
+            // Make sure the task count hasn't changed since when we choose this
+            // worker. Otherwise, restart the search.
+            if worker
+                .task_count
+                .compare_exchange(
+                    task_count,
+                    task_count + 1,
+                    Ordering::SeqCst,
+                    Ordering::Relaxed,
+                )
+                .is_ok()
+            {
+                return (worker, JobCountGuard(Arc::clone(&worker.task_count)));
+            }
+        }
+    }
+}
+
+/// Automatically decrements a worker's job count when a job finishes (when
+/// this gets dropped).
+struct JobCountGuard(Arc<AtomicUsize>);
+
+impl Drop for JobCountGuard {
+    fn drop(&mut self) {
+        // Decrement the job count
+        let previous_value = self.0.fetch_sub(1, Ordering::SeqCst);
+        debug_assert!(previous_value >= 1);
+    }
+}
+
+/// Calls abort on the handle when dropped.
+struct AbortGuard(AbortHandle);
+
+impl Drop for AbortGuard {
+    fn drop(&mut self) {
+        self.0.abort();
+    }
+}
+
+type PinnedFutureSpawner = Box<dyn FnOnce() + Send + 'static>;
+
+struct LocalWorkerHandle {
+    runtime_handle: tokio::runtime::Handle,
+    spawner: UnboundedSender<PinnedFutureSpawner>,
+    task_count: Arc<AtomicUsize>,
+}
+
+impl LocalWorkerHandle {
+    /// Create a new worker for executing pinned tasks
+    fn new_worker() -> LocalWorkerHandle {
+        let (sender, receiver) = unbounded_channel();
+        let runtime = Builder::new_current_thread()
+            .enable_all()
+            .build()
+            .expect("Failed to start a pinned worker thread runtime");
+        let runtime_handle = runtime.handle().clone();
+        let task_count = Arc::new(AtomicUsize::new(0));
+        let task_count_clone = Arc::clone(&task_count);
+
+        std::thread::spawn(|| Self::run(runtime, receiver, task_count_clone));
+
+        LocalWorkerHandle {
+            runtime_handle,
+            spawner: sender,
+            task_count,
+        }
+    }
+
+    fn run(
+        runtime: tokio::runtime::Runtime,
+        mut task_receiver: UnboundedReceiver<PinnedFutureSpawner>,
+        task_count: Arc<AtomicUsize>,
+    ) {
+        let local_set = LocalSet::new();
+        local_set.block_on(&runtime, async {
+            while let Some(spawn_task) = task_receiver.recv().await {
+                // Calls spawn_local(future)
+                (spawn_task)();
+            }
+        });
+
+        // If there are any tasks on the runtime associated with a LocalSet task
+        // that has already completed, but whose output has not yet been
+        // reported, let that task complete.
+        //
+        // Since the task_count is decremented when the runtime task exits,
+        // reading that counter lets us know if any such tasks completed during
+        // the call to `block_on`.
+        //
+        // Tasks on the LocalSet can't complete during this loop since they're
+        // stored on the LocalSet and we aren't accessing it.
+        let mut previous_task_count = task_count.load(Ordering::SeqCst);
+        loop {
+            // This call will also run tasks spawned on the runtime.
+            runtime.block_on(tokio::task::yield_now());
+            let new_task_count = task_count.load(Ordering::SeqCst);
+            if new_task_count == previous_task_count {
+                break;
+            } else {
+                previous_task_count = new_task_count;
+            }
+        }
+
+        // It's now no longer possible for a task on the runtime to be
+        // associated with a LocalSet task that has completed. Drop both the
+        // LocalSet and runtime to let tasks on the runtime be cancelled if and
+        // only if they are still on the LocalSet.
+        //
+        // Drop the LocalSet task first so that anyone awaiting the runtime
+        // JoinHandle will see the cancelled error after the LocalSet task
+        // destructor has completed.
+        drop(local_set);
+        drop(runtime);
+    }
+}

tokio-util/src/time/delay_queue.rs

@@ -9,8 +9,13 @@ use crate::time::wheel::{self, Wheel};
 use futures_core::ready;
 use tokio::time::{error::Error, sleep_until, Duration, Instant, Sleep};
 
+use core::ops::{Index, IndexMut};
 use slab::Slab;
 use std::cmp;
+use std::collections::HashMap;
+use std::convert::From;
+use std::fmt;
+use std::fmt::Debug;
 use std::future::Future;
 use std::marker::PhantomData;
 use std::pin::Pin;
@@ -128,7 +133,7 @@ use std::task::{self, Poll, Waker};
 #[derive(Debug)]
 pub struct DelayQueue<T> {
     /// Stores data associated with entries
-    slab: Slab<Data<T>>,
+    slab: SlabStorage<T>,
 
     /// Lookup structure tracking all delays in the queue
     wheel: Wheel<Stack<T>>,
@@ -152,6 +157,216 @@ pub struct DelayQueue<T> {
     waker: Option<Waker>,
 }
 
+#[derive(Default)]
+struct SlabStorage<T> {
+    inner: Slab<Data<T>>,
+
+    // A `compact` call requires a re-mapping of the `Key`s that were changed
+    // during the `compact` call of the `slab`. Since the keys that were given out
+    // cannot be changed retroactively we need to keep track of these re-mappings.
+    // The keys of `key_map` correspond to the old keys that were given out and
+    // the values to the `Key`s that were re-mapped by the `compact` call.
+    key_map: HashMap<Key, KeyInternal>,
+
+    // Index used to create new keys to hand out.
+    next_key_index: usize,
+
+    // Whether `compact` has been called, necessary in order to decide whether
+    // to include keys in `key_map`.
+    compact_called: bool,
+}
+
+impl<T> SlabStorage<T> {
+    pub(crate) fn with_capacity(capacity: usize) -> SlabStorage<T> {
+        SlabStorage {
+            inner: Slab::with_capacity(capacity),
+            key_map: HashMap::new(),
+            next_key_index: 0,
+            compact_called: false,
+        }
+    }
+
+    // Inserts data into the inner slab and re-maps keys if necessary
+    pub(crate) fn insert(&mut self, val: Data<T>) -> Key {
+        let mut key = KeyInternal::new(self.inner.insert(val));
+        let key_contained = self.key_map.contains_key(&key.into());
+
+        if key_contained {
+            // It's possible that a `compact` call creates capacitiy in `self.inner` in
+            // such a way that a `self.inner.insert` call creates a `key` which was
+            // previously given out during an `insert` call prior to the `compact` call.
+            // If `key` is contained in `self.key_map`, we have encountered this exact situation,
+            // We need to create a new key `key_to_give_out` and include the relation
+            // `key_to_give_out` -> `key` in `self.key_map`.
+            let key_to_give_out = self.create_new_key();
+            assert!(!self.key_map.contains_key(&key_to_give_out.into()));
+            self.key_map.insert(key_to_give_out.into(), key);
+            key = key_to_give_out;
+        } else if self.compact_called {
+            // Include an identity mapping in `self.key_map` in order to allow us to
+            // panic if a key that was handed out is removed more than once.
+            self.key_map.insert(key.into(), key);
+        }
+
+        key.into()
+    }
+
+    // Re-map the key in case compact was previously called.
+    // Note: Since we include identity mappings in key_map after compact was called,
+    // we have information about all keys that were handed out. In the case in which
+    // compact was called and we try to remove a Key that was previously removed
+    // we can detect invalid keys if no key is found in `key_map`. This is necessary
+    // in order to prevent situations in which a previously removed key
+    // corresponds to a re-mapped key internally and which would then be incorrectly
+    // removed from the slab.
+    //
+    // Example to illuminate this problem:
+    //
+    // Let's assume our `key_map` is {1 -> 2, 2 -> 1} and we call remove(1). If we
+    // were to remove 1 again, we would not find it inside `key_map` anymore.
+    // If we were to imply from this that no re-mapping was necessary, we would
+    // incorrectly remove 1 from `self.slab.inner`, which corresponds to the
+    // handed-out key 2.
+    pub(crate) fn remove(&mut self, key: &Key) -> Data<T> {
+        let remapped_key = if self.compact_called {
+            match self.key_map.remove(key) {
+                Some(key_internal) => key_internal,
+                None => panic!("invalid key"),
+            }
+        } else {
+            (*key).into()
+        };
+
+        self.inner.remove(remapped_key.index)
+    }
+
+    pub(crate) fn shrink_to_fit(&mut self) {
+        self.inner.shrink_to_fit();
+        self.key_map.shrink_to_fit();
+    }
+
+    pub(crate) fn compact(&mut self) {
+        if !self.compact_called {
+            for (key, _) in self.inner.iter() {
+                self.key_map.insert(Key::new(key), KeyInternal::new(key));
+            }
+        }
+
+        let mut remapping = HashMap::new();
+        self.inner.compact(|_, from, to| {
+            remapping.insert(from, to);
+            true
+        });
+
+        // At this point `key_map` contains a mapping for every element.
+        for internal_key in self.key_map.values_mut() {
+            if let Some(new_internal_key) = remapping.get(&internal_key.index) {
+                *internal_key = KeyInternal::new(*new_internal_key);
+            }
+        }
+
+        if self.key_map.capacity() > 2 * self.key_map.len() {
+            self.key_map.shrink_to_fit();
+        }
+
+        self.compact_called = true;
+    }
+
+    // Tries to re-map a `Key` that was given out to the user to its
+    // corresponding internal key.
+    fn remap_key(&self, key: &Key) -> Option<KeyInternal> {
+        let key_map = &self.key_map;
+        if self.compact_called {
+            key_map.get(&*key).copied()
+        } else {
+            Some((*key).into())
+        }
+    }
+
+    fn create_new_key(&mut self) -> KeyInternal {
+        while self.key_map.contains_key(&Key::new(self.next_key_index)) {
+            self.next_key_index = self.next_key_index.wrapping_add(1);
+        }
+
+        KeyInternal::new(self.next_key_index)
+    }
+
+    pub(crate) fn len(&self) -> usize {
+        self.inner.len()
+    }
+
+    pub(crate) fn capacity(&self) -> usize {
+        self.inner.capacity()
+    }
+
+    pub(crate) fn clear(&mut self) {
+        self.inner.clear();
+        self.key_map.clear();
+        self.compact_called = false;
+    }
+
+    pub(crate) fn reserve(&mut self, additional: usize) {
+        self.inner.reserve(additional);
+
+        if self.compact_called {
+            self.key_map.reserve(additional);
+        }
+    }
+
+    pub(crate) fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+
+    pub(crate) fn contains(&self, key: &Key) -> bool {
+        let remapped_key = self.remap_key(key);
+
+        match remapped_key {
+            Some(internal_key) => self.inner.contains(internal_key.index),
+            None => false,
+        }
+    }
+}
+
+impl<T> fmt::Debug for SlabStorage<T>
+where
+    T: fmt::Debug,
+{
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if fmt.alternate() {
+            fmt.debug_map().entries(self.inner.iter()).finish()
+        } else {
+            fmt.debug_struct("Slab")
+                .field("len", &self.len())
+                .field("cap", &self.capacity())
+                .finish()
+        }
+    }
+}
+
+impl<T> Index<Key> for SlabStorage<T> {
+    type Output = Data<T>;
+
+    fn index(&self, key: Key) -> &Self::Output {
+        let remapped_key = self.remap_key(&key);
+
+        match remapped_key {
+            Some(internal_key) => &self.inner[internal_key.index],
+            None => panic!("Invalid index {}", key.index),
+        }
+    }
+}
+
+impl<T> IndexMut<Key> for SlabStorage<T> {
+    fn index_mut(&mut self, key: Key) -> &mut Data<T> {
+        let remapped_key = self.remap_key(&key);
+
+        match remapped_key {
+            Some(internal_key) => &mut self.inner[internal_key.index],
+            None => panic!("Invalid index {}", key.index),
+        }
+    }
+}
+
 /// An entry in `DelayQueue` that has expired and been removed.
 ///
 /// Values are returned by [`DelayQueue::poll_expired`].
@@ -176,15 +391,23 @@ pub struct Expired<T> {
 ///
 /// [`DelayQueue`]: struct@DelayQueue
 /// [`DelayQueue::insert`]: method@DelayQueue::insert
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Key {
     index: usize,
 }
 
+// Whereas `Key` is given out to users that use `DelayQueue`, internally we use
+// `KeyInternal` as the key type in order to make the logic of mapping between keys
+// as a result of `compact` calls clearer.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+struct KeyInternal {
+    index: usize,
+}
+
 #[derive(Debug)]
 struct Stack<T> {
     /// Head of the stack
-    head: Option<usize>,
+    head: Option<Key>,
     _p: PhantomData<fn() -> T>,
 }
 
@@ -201,10 +424,10 @@ struct Data<T> {
     expired: bool,
 
     /// Next entry in the stack
-    next: Option<usize>,
+    next: Option<Key>,
 
     /// Previous entry in the stack
-    prev: Option<usize>,
+    prev: Option<Key>,
 }
 
 /// Maximum number of entries the queue can handle
@@ -253,7 +476,7 @@ impl<T> DelayQueue<T> {
     pub fn with_capacity(capacity: usize) -> DelayQueue<T> {
         DelayQueue {
             wheel: Wheel::new(),
-            slab: Slab::with_capacity(capacity),
+            slab: SlabStorage::with_capacity(capacity),
             expired: Stack::default(),
             delay: None,
             wheel_now: 0,
@@ -348,7 +571,7 @@ impl<T> DelayQueue<T> {
             }
         }
 
-        Key::new(key)
+        key
     }
 
     /// Attempts to pull out the next value of the delay queue, registering the
@@ -369,13 +592,13 @@ impl<T> DelayQueue<T> {
 
         let item = ready!(self.poll_idx(cx));
         Poll::Ready(item.map(|result| {
-            result.map(|idx| {
-                let data = self.slab.remove(idx);
+            result.map(|key| {
+                let data = self.slab.remove(&key);
                 debug_assert!(data.next.is_none());
                 debug_assert!(data.prev.is_none());
 
                 Expired {
-                    key: Key::new(idx),
+                    key,
                     data: data.inner,
                     deadline: self.start + Duration::from_millis(data.when),
                 }
@@ -437,7 +660,7 @@ impl<T> DelayQueue<T> {
         self.insert_at(value, Instant::now() + timeout)
     }
 
-    fn insert_idx(&mut self, when: u64, key: usize) {
+    fn insert_idx(&mut self, when: u64, key: Key) {
         use self::wheel::{InsertError, Stack};
 
         // Register the deadline with the timer wheel
@@ -462,10 +685,10 @@ impl<T> DelayQueue<T> {
         use crate::time::wheel::Stack;
 
         // Special case the `expired` queue
-        if self.slab[key.index].expired {
-            self.expired.remove(&key.index, &mut self.slab);
+        if self.slab[*key].expired {
+            self.expired.remove(key, &mut self.slab);
         } else {
-            self.wheel.remove(&key.index, &mut self.slab);
+            self.wheel.remove(key, &mut self.slab);
         }
     }
 
@@ -498,8 +721,19 @@ impl<T> DelayQueue<T> {
     /// # }
     /// ```
     pub fn remove(&mut self, key: &Key) -> Expired<T> {
+        let prev_deadline = self.next_deadline();
+
         self.remove_key(key);
-        let data = self.slab.remove(key.index);
+        let data = self.slab.remove(key);
+
+        let next_deadline = self.next_deadline();
+        if prev_deadline != next_deadline {
+            match (next_deadline, &mut self.delay) {
+                (None, _) => self.delay = None,
+                (Some(deadline), Some(delay)) => delay.as_mut().reset(deadline),
+                (Some(deadline), None) => self.delay = Some(Box::pin(sleep_until(deadline))),
+            }
+        }
 
         Expired {
             key: Key::new(key.index),
@@ -548,10 +782,10 @@ impl<T> DelayQueue<T> {
         // Normalize the deadline. Values cannot be set to expire in the past.
         let when = self.normalize_deadline(when);
 
-        self.slab[key.index].when = when;
-        self.slab[key.index].expired = false;
+        self.slab[*key].when = when;
+        self.slab[*key].expired = false;
 
-        self.insert_idx(when, key.index);
+        self.insert_idx(when, *key);
 
         let next_deadline = self.next_deadline();
         if let (Some(ref mut delay), Some(deadline)) = (&mut self.delay, next_deadline) {
@@ -560,6 +794,50 @@ impl<T> DelayQueue<T> {
         }
     }
 
+    /// Shrink the capacity of the slab, which `DelayQueue` uses internally for storage allocation.
+    /// This function is not guaranteed to, and in most cases, won't decrease the capacity of the slab
+    /// to the number of elements still contained in it, because elements cannot be moved to a different
+    /// index. To decrease the capacity to the size of the slab use [`compact`].
+    ///
+    /// This function can take O(n) time even when the capacity cannot be reduced or the allocation is
+    /// shrunk in place. Repeated calls run in O(1) though.
+    ///
+    /// [`compact`]: method@Self::compact
+    pub fn shrink_to_fit(&mut self) {
+        self.slab.shrink_to_fit();
+    }
+
+    /// Shrink the capacity of the slab, which `DelayQueue` uses internally for storage allocation,
+    /// to the number of elements that are contained in it.
+    ///
+    /// This methods runs in O(n).
+    ///
+    /// # Examples
+    ///
+    /// Basic usage
+    ///
+    /// ```rust
+    /// use tokio_util::time::DelayQueue;
+    /// use std::time::Duration;
+    ///
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// let mut delay_queue = DelayQueue::with_capacity(10);
+    ///
+    /// let key1 = delay_queue.insert(5, Duration::from_secs(5));
+    /// let key2 = delay_queue.insert(10, Duration::from_secs(10));
+    /// let key3 = delay_queue.insert(15, Duration::from_secs(15));
+    ///
+    /// delay_queue.remove(&key2);
+    ///
+    /// delay_queue.compact();
+    /// assert_eq!(delay_queue.capacity(), 2);
+    /// # }
+    /// ```
+    pub fn compact(&mut self) {
+        self.slab.compact();
+    }
+
     /// Returns the next time to poll as determined by the wheel
     fn next_deadline(&mut self) -> Option<Instant> {
         self.wheel
@@ -739,7 +1017,7 @@ impl<T> DelayQueue<T> {
     /// should be returned.
     ///
     /// A slot should be returned when the associated deadline has been reached.
-    fn poll_idx(&mut self, cx: &mut task::Context<'_>) -> Poll<Option<Result<usize, Error>>> {
+    fn poll_idx(&mut self, cx: &mut task::Context<'_>) -> Poll<Option<Result<Key, Error>>> {
         use self::wheel::Stack;
 
         let expired = self.expired.pop(&mut self.slab);
@@ -805,9 +1083,9 @@ impl<T> futures_core::Stream for DelayQueue<T> {
 }
 
 impl<T> wheel::Stack for Stack<T> {
-    type Owned = usize;
-    type Borrowed = usize;
-    type Store = Slab<Data<T>>;
+    type Owned = Key;
+    type Borrowed = Key;
+    type Store = SlabStorage<T>;
 
     fn is_empty(&self) -> bool {
         self.head.is_none()
@@ -826,28 +1104,29 @@ impl<T> wheel::Stack for Stack<T> {
         }
 
         store[item].next = old;
-        self.head = Some(item)
+        self.head = Some(item);
     }
 
     fn pop(&mut self, store: &mut Self::Store) -> Option<Self::Owned> {
-        if let Some(idx) = self.head {
-            self.head = store[idx].next;
+        if let Some(key) = self.head {
+            self.head = store[key].next;
 
             if let Some(idx) = self.head {
                 store[idx].prev = None;
             }
 
-            store[idx].next = None;
-            debug_assert!(store[idx].prev.is_none());
+            store[key].next = None;
+            debug_assert!(store[key].prev.is_none());
 
-            Some(idx)
+            Some(key)
         } else {
             None
         }
     }
 
     fn remove(&mut self, item: &Self::Borrowed, store: &mut Self::Store) {
-        assert!(store.contains(*item));
+        let key = *item;
+        assert!(store.contains(item));
 
         // Ensure that the entry is in fact contained by the stack
         debug_assert!({
@@ -856,29 +1135,31 @@ impl<T> wheel::Stack for Stack<T> {
             let mut contains = false;
 
             while let Some(idx) = next {
+                let data = &store[idx];
+
                 if idx == *item {
                     debug_assert!(!contains);
                     contains = true;
                 }
 
-                next = store[idx].next;
+                next = data.next;
             }
 
             contains
         });
 
-        if let Some(next) = store[*item].next {
-            store[next].prev = store[*item].prev;
+        if let Some(next) = store[key].next {
+            store[next].prev = store[key].prev;
         }
 
-        if let Some(prev) = store[*item].prev {
-            store[prev].next = store[*item].next;
+        if let Some(prev) = store[key].prev {
+            store[prev].next = store[key].next;
         } else {
-            self.head = store[*item].next;
+            self.head = store[key].next;
         }
 
-        store[*item].next = None;
-        store[*item].prev = None;
+        store[key].next = None;
+        store[key].prev = None;
     }
 
     fn when(item: &Self::Borrowed, store: &Self::Store) -> u64 {
@@ -901,6 +1182,24 @@ impl Key {
     }
 }
 
+impl KeyInternal {
+    pub(crate) fn new(index: usize) -> KeyInternal {
+        KeyInternal { index }
+    }
+}
+
+impl From<Key> for KeyInternal {
+    fn from(item: Key) -> Self {
+        KeyInternal::new(item.index)
+    }
+}
+
+impl From<KeyInternal> for Key {
+    fn from(item: KeyInternal) -> Self {
+        Key::new(item.index)
+    }
+}
+
 impl<T> Expired<T> {
     /// Returns a reference to the inner value.
     pub fn get_ref(&self) -> &T {
@@ -921,4 +1220,9 @@ impl<T> Expired<T> {
     pub fn deadline(&self) -> Instant {
         self.deadline
     }
+
+    /// Returns the key that the expiration is indexed by.
+    pub fn key(&self) -> Key {
+        self.key
+    }
 }

tokio-util/src/time/mod.rs

@@ -12,9 +12,9 @@ use std::time::Duration;
 
 mod wheel;
 
-#[doc(inline)]
 pub mod delay_queue;
 
+#[doc(inline)]
 pub use delay_queue::DelayQueue;
 
 // ===== Internal utils =====

tokio-util/src/time/wheel/mod.rs

@@ -6,6 +6,7 @@ mod stack;
 pub(crate) use self::stack::Stack;
 
 use std::borrow::Borrow;
+use std::fmt::Debug;
 use std::usize;
 
 /// Timing wheel implementation.

tokio-util/src/time/wheel/stack.rs

@@ -1,4 +1,6 @@
 use std::borrow::Borrow;
+use std::cmp::Eq;
+use std::hash::Hash;
 
 /// Abstracts the stack operations needed to track timeouts.
 pub(crate) trait Stack: Default {
@@ -6,7 +8,7 @@ pub(crate) trait Stack: Default {
     type Owned: Borrow<Self::Borrowed>;
 
     /// Borrowed item
-    type Borrowed;
+    type Borrowed: Eq + Hash;
 
     /// Item storage, this allows a slab to be used instead of just the heap
     type Store;

tokio-util/src/udp/frame.rs

@@ -35,7 +35,6 @@ use std::{io, mem::MaybeUninit};
 /// [`Sink`]: futures_sink::Sink
 /// [`split`]: https://docs.rs/futures/0.3/futures/stream/trait.StreamExt.html#method.split
 #[must_use = "sinks do nothing unless polled"]
-#[cfg_attr(docsrs, doc(cfg(all(feature = "codec", feature = "udp"))))]
 #[derive(Debug)]
 pub struct UdpFramed<C, T = UdpSocket> {
     socket: T,
@@ -144,7 +143,7 @@ where
             ..
         } = *self;
 
-        let n = ready!(socket.borrow().poll_send_to(cx, &wr, *out_addr))?;
+        let n = ready!(socket.borrow().poll_send_to(cx, wr, *out_addr))?;
 
         let wrote_all = n == self.wr.len();
         self.wr.clear();

tokio-util/tests/framed.rs

@@ -12,7 +12,10 @@ use std::task::{Context, Poll};
 const INITIAL_CAPACITY: usize = 8 * 1024;
 
 /// Encode and decode u32 values.
-struct U32Codec;
+#[derive(Default)]
+struct U32Codec {
+    read_bytes: usize,
+}
 
 impl Decoder for U32Codec {
     type Item = u32;
@@ -24,6 +27,7 @@ impl Decoder for U32Codec {
         }
 
         let n = buf.split_to(4).get_u32();
+        self.read_bytes += 4;
         Ok(Some(n))
     }
 }
@@ -39,6 +43,38 @@ impl Encoder<u32> for U32Codec {
     }
 }
 
+/// Encode and decode u64 values.
+#[derive(Default)]
+struct U64Codec {
+    read_bytes: usize,
+}
+
+impl Decoder for U64Codec {
+    type Item = u64;
+    type Error = io::Error;
+
+    fn decode(&mut self, buf: &mut BytesMut) -> io::Result<Option<u64>> {
+        if buf.len() < 8 {
+            return Ok(None);
+        }
+
+        let n = buf.split_to(8).get_u64();
+        self.read_bytes += 8;
+        Ok(Some(n))
+    }
+}
+
+impl Encoder<u64> for U64Codec {
+    type Error = io::Error;
+
+    fn encode(&mut self, item: u64, dst: &mut BytesMut) -> io::Result<()> {
+        // Reserve space
+        dst.reserve(8);
+        dst.put_u64(item);
+        Ok(())
+    }
+}
+
 /// This value should never be used
 struct DontReadIntoThis;
 
@@ -63,18 +99,39 @@ impl tokio::io::AsyncRead for DontReadIntoThis {
 
 #[tokio::test]
 async fn can_read_from_existing_buf() {
-    let mut parts = FramedParts::new(DontReadIntoThis, U32Codec);
+    let mut parts = FramedParts::new(DontReadIntoThis, U32Codec::default());
     parts.read_buf = BytesMut::from(&[0, 0, 0, 42][..]);
 
     let mut framed = Framed::from_parts(parts);
     let num = assert_ok!(framed.next().await.unwrap());
 
     assert_eq!(num, 42);
+    assert_eq!(framed.codec().read_bytes, 4);
+}
+
+#[tokio::test]
+async fn can_read_from_existing_buf_after_codec_changed() {
+    let mut parts = FramedParts::new(DontReadIntoThis, U32Codec::default());
+    parts.read_buf = BytesMut::from(&[0, 0, 0, 42, 0, 0, 0, 0, 0, 0, 0, 84][..]);
+
+    let mut framed = Framed::from_parts(parts);
+    let num = assert_ok!(framed.next().await.unwrap());
+
+    assert_eq!(num, 42);
+    assert_eq!(framed.codec().read_bytes, 4);
+
+    let mut framed = framed.map_codec(|codec| U64Codec {
+        read_bytes: codec.read_bytes,
+    });
+    let num = assert_ok!(framed.next().await.unwrap());
+
+    assert_eq!(num, 84);
+    assert_eq!(framed.codec().read_bytes, 12);
 }
 
 #[test]
 fn external_buf_grows_to_init() {
-    let mut parts = FramedParts::new(DontReadIntoThis, U32Codec);
+    let mut parts = FramedParts::new(DontReadIntoThis, U32Codec::default());
     parts.read_buf = BytesMut::from(&[0, 0, 0, 42][..]);
 
     let framed = Framed::from_parts(parts);
@@ -85,7 +142,7 @@ fn external_buf_grows_to_init() {
 
 #[test]
 fn external_buf_does_not_shrink() {
-    let mut parts = FramedParts::new(DontReadIntoThis, U32Codec);
+    let mut parts = FramedParts::new(DontReadIntoThis, U32Codec::default());
     parts.read_buf = BytesMut::from(&vec![0; INITIAL_CAPACITY * 2][..]);
 
     let framed = Framed::from_parts(parts);

tokio-util/tests/framed_read.rs

@@ -50,6 +50,22 @@ impl Decoder for U32Decoder {
     }
 }
 
+struct U64Decoder;
+
+impl Decoder for U64Decoder {
+    type Item = u64;
+    type Error = io::Error;
+
+    fn decode(&mut self, buf: &mut BytesMut) -> io::Result<Option<u64>> {
+        if buf.len() < 8 {
+            return Ok(None);
+        }
+
+        let n = buf.split_to(8).get_u64();
+        Ok(Some(n))
+    }
+}
+
 #[test]
 fn read_multi_frame_in_packet() {
     let mut task = task::spawn(());
@@ -84,6 +100,24 @@ fn read_multi_frame_across_packets() {
     });
 }
 
+#[test]
+fn read_multi_frame_in_packet_after_codec_changed() {
+    let mut task = task::spawn(());
+    let mock = mock! {
+        Ok(b"\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x08".to_vec()),
+    };
+    let mut framed = FramedRead::new(mock, U32Decoder);
+
+    task.enter(|cx, _| {
+        assert_read!(pin!(framed).poll_next(cx), 0x04);
+
+        let mut framed = framed.map_decoder(|_| U64Decoder);
+        assert_read!(pin!(framed).poll_next(cx), 0x08);
+
+        assert!(assert_ready!(pin!(framed).poll_next(cx)).is_none());
+    });
+}
+
 #[test]
 fn read_not_ready() {
     let mut task = task::spawn(());

tokio-util/tests/framed_stream.rs

@@ -0,0 +1,38 @@
+use futures_core::stream::Stream;
+use std::{io, pin::Pin};
+use tokio_test::{assert_ready, io::Builder, task};
+use tokio_util::codec::{BytesCodec, FramedRead};
+
+macro_rules! pin {
+    ($id:ident) => {
+        Pin::new(&mut $id)
+    };
+}
+
+macro_rules! assert_read {
+    ($e:expr, $n:expr) => {{
+        let val = assert_ready!($e);
+        assert_eq!(val.unwrap().unwrap(), $n);
+    }};
+}
+
+#[tokio::test]
+async fn return_none_after_error() {
+    let mut io = FramedRead::new(
+        Builder::new()
+            .read(b"abcdef")
+            .read_error(io::Error::new(io::ErrorKind::Other, "Resource errored out"))
+            .read(b"more data")
+            .build(),
+        BytesCodec::new(),
+    );
+
+    let mut task = task::spawn(());
+
+    task.enter(|cx, _| {
+        assert_read!(pin!(io).poll_next(cx), b"abcdef".to_vec());
+        assert!(assert_ready!(pin!(io).poll_next(cx)).unwrap().is_err());
+        assert!(assert_ready!(pin!(io).poll_next(cx)).is_none());
+        assert_read!(pin!(io).poll_next(cx), b"more data".to_vec());
+    })
+}

tokio-util/tests/framed_write.rs

@@ -39,6 +39,19 @@ impl Encoder<u32> for U32Encoder {
     }
 }
 
+struct U64Encoder;
+
+impl Encoder<u64> for U64Encoder {
+    type Error = io::Error;
+
+    fn encode(&mut self, item: u64, dst: &mut BytesMut) -> io::Result<()> {
+        // Reserve space
+        dst.reserve(8);
+        dst.put_u64(item);
+        Ok(())
+    }
+}
+
 #[test]
 fn write_multi_frame_in_packet() {
     let mut task = task::spawn(());
@@ -65,6 +78,32 @@ fn write_multi_frame_in_packet() {
     });
 }
 
+#[test]
+fn write_multi_frame_after_codec_changed() {
+    let mut task = task::spawn(());
+    let mock = mock! {
+        Ok(b"\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x08".to_vec()),
+    };
+    let mut framed = FramedWrite::new(mock, U32Encoder);
+
+    task.enter(|cx, _| {
+        assert!(assert_ready!(pin!(framed).poll_ready(cx)).is_ok());
+        assert!(pin!(framed).start_send(0x04).is_ok());
+
+        let mut framed = framed.map_encoder(|_| U64Encoder);
+        assert!(assert_ready!(pin!(framed).poll_ready(cx)).is_ok());
+        assert!(pin!(framed).start_send(0x08).is_ok());
+
+        // Nothing written yet
+        assert_eq!(1, framed.get_ref().calls.len());
+
+        // Flush the writes
+        assert!(assert_ready!(pin!(framed).poll_flush(cx)).is_ok());
+
+        assert_eq!(0, framed.get_ref().calls.len());
+    });
+}
+
 #[test]
 fn write_hits_backpressure() {
     const ITER: usize = 2 * 1024;

tokio-util/tests/io_sync_bridge.rs

@@ -0,0 +1,43 @@
+#![cfg(feature = "io-util")]
+
+use std::error::Error;
+use std::io::{Cursor, Read, Result as IoResult};
+use tokio::io::AsyncRead;
+use tokio_util::io::SyncIoBridge;
+
+async fn test_reader_len(
+    r: impl AsyncRead + Unpin + Send + 'static,
+    expected_len: usize,
+) -> IoResult<()> {
+    let mut r = SyncIoBridge::new(r);
+    let res = tokio::task::spawn_blocking(move || {
+        let mut buf = Vec::new();
+        r.read_to_end(&mut buf)?;
+        Ok::<_, std::io::Error>(buf)
+    })
+    .await?;
+    assert_eq!(res?.len(), expected_len);
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_read_to_sync() -> Result<(), Box<dyn Error>> {
+    test_reader_len(tokio::io::empty(), 0).await?;
+    let buf = b"hello world";
+    test_reader_len(Cursor::new(buf), buf.len()).await?;
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_write_to_sync() -> Result<(), Box<dyn Error>> {
+    let mut dest = Vec::new();
+    let src = b"hello world";
+    let dest = tokio::task::spawn_blocking(move || -> Result<_, String> {
+        let mut w = SyncIoBridge::new(Cursor::new(&mut dest));
+        std::io::copy(&mut Cursor::new(src), &mut w).map_err(|e| e.to_string())?;
+        Ok(dest)
+    })
+    .await??;
+    assert_eq!(dest.as_slice(), src);
+    Ok(())
+}

tokio-util/tests/poll_semaphore.rs

@@ -6,9 +6,9 @@ use tokio_util::sync::PollSemaphore;
 
 type SemRet = Option<OwnedSemaphorePermit>;
 
-fn semaphore_poll<'a>(
-    sem: &'a mut PollSemaphore,
-) -> tokio_test::task::Spawn<impl Future<Output = SemRet> + 'a> {
+fn semaphore_poll(
+    sem: &mut PollSemaphore,
+) -> tokio_test::task::Spawn<impl Future<Output = SemRet> + '_> {
     let fut = futures::future::poll_fn(move |cx| sem.poll_acquire(cx));
     tokio_test::task::spawn(fut)
 }

tokio-util/tests/spawn_pinned.rs

@@ -0,0 +1,193 @@
+#![warn(rust_2018_idioms)]
+
+use std::rc::Rc;
+use std::sync::Arc;
+use tokio_util::task;
+
+/// Simple test of running a !Send future via spawn_pinned
+#[tokio::test]
+async fn can_spawn_not_send_future() {
+    let pool = task::LocalPoolHandle::new(1);
+
+    let output = pool
+        .spawn_pinned(|| {
+            // Rc is !Send + !Sync
+            let local_data = Rc::new("test");
+
+            // This future holds an Rc, so it is !Send
+            async move { local_data.to_string() }
+        })
+        .await
+        .unwrap();
+
+    assert_eq!(output, "test");
+}
+
+/// Dropping the join handle still lets the task execute
+#[test]
+fn can_drop_future_and_still_get_output() {
+    let pool = task::LocalPoolHandle::new(1);
+    let (sender, receiver) = std::sync::mpsc::channel();
+
+    let _ = pool.spawn_pinned(move || {
+        // Rc is !Send + !Sync
+        let local_data = Rc::new("test");
+
+        // This future holds an Rc, so it is !Send
+        async move {
+            let _ = sender.send(local_data.to_string());
+        }
+    });
+
+    assert_eq!(receiver.recv(), Ok("test".to_string()));
+}
+
+#[test]
+#[should_panic(expected = "assertion failed: pool_size > 0")]
+fn cannot_create_zero_sized_pool() {
+    let _pool = task::LocalPoolHandle::new(0);
+}
+
+/// We should be able to spawn multiple futures onto the pool at the same time.
+#[tokio::test]
+async fn can_spawn_multiple_futures() {
+    let pool = task::LocalPoolHandle::new(2);
+
+    let join_handle1 = pool.spawn_pinned(|| {
+        let local_data = Rc::new("test1");
+        async move { local_data.to_string() }
+    });
+    let join_handle2 = pool.spawn_pinned(|| {
+        let local_data = Rc::new("test2");
+        async move { local_data.to_string() }
+    });
+
+    assert_eq!(join_handle1.await.unwrap(), "test1");
+    assert_eq!(join_handle2.await.unwrap(), "test2");
+}
+
+/// A panic in the spawned task causes the join handle to return an error.
+/// But, you can continue to spawn tasks.
+#[tokio::test]
+async fn task_panic_propagates() {
+    let pool = task::LocalPoolHandle::new(1);
+
+    let join_handle = pool.spawn_pinned(|| async {
+        panic!("Test panic");
+    });
+
+    let result = join_handle.await;
+    assert!(result.is_err());
+    let error = result.unwrap_err();
+    assert!(error.is_panic());
+    let panic_str: &str = *error.into_panic().downcast().unwrap();
+    assert_eq!(panic_str, "Test panic");
+
+    // Trying again with a "safe" task still works
+    let join_handle = pool.spawn_pinned(|| async { "test" });
+    let result = join_handle.await;
+    assert!(result.is_ok());
+    assert_eq!(result.unwrap(), "test");
+}
+
+/// A panic during task creation causes the join handle to return an error.
+/// But, you can continue to spawn tasks.
+#[tokio::test]
+async fn callback_panic_does_not_kill_worker() {
+    let pool = task::LocalPoolHandle::new(1);
+
+    let join_handle = pool.spawn_pinned(|| {
+        panic!("Test panic");
+        #[allow(unreachable_code)]
+        async {}
+    });
+
+    let result = join_handle.await;
+    assert!(result.is_err());
+    let error = result.unwrap_err();
+    assert!(error.is_panic());
+    let panic_str: &str = *error.into_panic().downcast().unwrap();
+    assert_eq!(panic_str, "Test panic");
+
+    // Trying again with a "safe" callback works
+    let join_handle = pool.spawn_pinned(|| async { "test" });
+    let result = join_handle.await;
+    assert!(result.is_ok());
+    assert_eq!(result.unwrap(), "test");
+}
+
+/// Canceling the task via the returned join handle cancels the spawned task
+/// (which has a different, internal join handle).
+#[tokio::test]
+async fn task_cancellation_propagates() {
+    let pool = task::LocalPoolHandle::new(1);
+    let notify_dropped = Arc::new(());
+    let weak_notify_dropped = Arc::downgrade(&notify_dropped);
+
+    let (start_sender, start_receiver) = tokio::sync::oneshot::channel();
+    let (drop_sender, drop_receiver) = tokio::sync::oneshot::channel::<()>();
+    let join_handle = pool.spawn_pinned(|| async move {
+        let _drop_sender = drop_sender;
+        // Move the Arc into the task
+        let _notify_dropped = notify_dropped;
+        let _ = start_sender.send(());
+
+        // Keep the task running until it gets aborted
+        futures::future::pending::<()>().await;
+    });
+
+    // Wait for the task to start
+    let _ = start_receiver.await;
+
+    join_handle.abort();
+
+    // Wait for the inner task to abort, dropping the sender.
+    // The top level join handle aborts quicker than the inner task (the abort
+    // needs to propagate and get processed on the worker thread), so we can't
+    // just await the top level join handle.
+    let _ = drop_receiver.await;
+
+    // Check that the Arc has been dropped. This verifies that the inner task
+    // was canceled as well.
+    assert!(weak_notify_dropped.upgrade().is_none());
+}
+
+/// Tasks should be given to the least burdened worker. When spawning two tasks
+/// on a pool with two empty workers the tasks should be spawned on separate
+/// workers.
+#[tokio::test]
+async fn tasks_are_balanced() {
+    let pool = task::LocalPoolHandle::new(2);
+
+    // Spawn a task so one thread has a task count of 1
+    let (start_sender1, start_receiver1) = tokio::sync::oneshot::channel();
+    let (end_sender1, end_receiver1) = tokio::sync::oneshot::channel();
+    let join_handle1 = pool.spawn_pinned(|| async move {
+        let _ = start_sender1.send(());
+        let _ = end_receiver1.await;
+        std::thread::current().id()
+    });
+
+    // Wait for the first task to start up
+    let _ = start_receiver1.await;
+
+    // This task should be spawned on the other thread
+    let (start_sender2, start_receiver2) = tokio::sync::oneshot::channel();
+    let join_handle2 = pool.spawn_pinned(|| async move {
+        let _ = start_sender2.send(());
+        std::thread::current().id()
+    });
+
+    // Wait for the second task to start up
+    let _ = start_receiver2.await;
+
+    // Allow the first task to end
+    let _ = end_sender1.send(());
+
+    let thread_id1 = join_handle1.await.unwrap();
+    let thread_id2 = join_handle2.await.unwrap();
+
+    // Since the first task was active when the second task spawned, they should
+    // be on separate workers/threads.
+    assert_ne!(thread_id1, thread_id2);
+}