chore: prepare Tokio v1.35.0 (#6197)

This reverts commit 2400769b54.

.cargo/config

@@ -1,2 +0,0 @@
-# [build]
-# rustflags = ["--cfg", "tokio_unstable"]

.cirrus.yml

@@ -1,8 +1,10 @@
+only_if: $CIRRUS_TAG == '' && ($CIRRUS_PR != '' || $CIRRUS_BRANCH == 'master' || $CIRRUS_BRANCH =~ 'tokio-.*')
+auto_cancellation: $CIRRUS_BRANCH != 'master' && $CIRRUS_BRANCH !=~ 'tokio-.*'
 freebsd_instance:
-  image: freebsd-12-3-release-amd64
+  image_family: freebsd-13-1
 env:
   RUST_STABLE: stable
-  RUST_NIGHTLY: nightly-2022-10-25
+  RUST_NIGHTLY: nightly-2023-10-21
   RUSTFLAGS: -D warnings
 
 # Test FreeBSD in a full VM on cirrus-ci.com.  Test the i686 target too, in the
@@ -11,9 +13,8 @@ env:
 # the system's binaries, so the environment shouldn't matter.
 task:
   name: FreeBSD 64-bit
-  auto_cancellation: $CIRRUS_BRANCH != 'master' && $CIRRUS_BRANCH !=~ 'tokio-.*'
   setup_script:
-    - pkg install -y bash curl
+    - pkg install -y bash
     - curl https://sh.rustup.rs -sSf --output rustup.sh
     - sh rustup.sh -y --profile minimal --default-toolchain $RUST_STABLE
     - . $HOME/.cargo/env
@@ -26,12 +27,11 @@ task:
 
 task:
   name: FreeBSD docs
-  auto_cancellation: $CIRRUS_BRANCH != 'master' && $CIRRUS_BRANCH !=~ 'tokio-.*'
   env:
     RUSTFLAGS: --cfg docsrs --cfg tokio_unstable
     RUSTDOCFLAGS: --cfg docsrs --cfg tokio_unstable -Dwarnings
   setup_script:
-    - pkg install -y bash curl
+    - pkg install -y bash
     - curl https://sh.rustup.rs -sSf --output rustup.sh
     - sh rustup.sh -y --profile minimal --default-toolchain $RUST_NIGHTLY
     - . $HOME/.cargo/env
@@ -44,9 +44,8 @@ task:
 
 task:
   name: FreeBSD 32-bit
-  auto_cancellation: $CIRRUS_BRANCH != 'master' && $CIRRUS_BRANCH !=~ 'tokio-.*'
   setup_script:
-    - pkg install -y bash curl
+    - pkg install -y bash
     - curl https://sh.rustup.rs -sSf --output rustup.sh
     - sh rustup.sh -y --profile minimal --default-toolchain $RUST_STABLE
     - . $HOME/.cargo/env

.clippy.toml

@@ -1 +1 @@
-msrv = "1.49"
+msrv = "1.56"

.github/labeler.yml

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

.github/workflows/audit.yml

@@ -15,15 +15,16 @@ permissions:
 jobs:
   security-audit:
     permissions:
-      checks: write  # for actions-rs/audit-check to create check
+      checks: write  # for rustsec/audit-check to create check
       contents: read  # for actions/checkout to fetch code
-      issues: write  # for actions-rs/audit-check to create issues
+      issues: write  # for rustsec/audit-check to create issues
     runs-on: ubuntu-latest
     if: "!contains(github.event.head_commit.message, 'ci skip')"
     steps:
       - uses: actions/checkout@v3
 
       - name: Audit Check
-        uses: actions-rs/audit-check@v1
+        # https://github.com/rustsec/audit-check/issues/2
+        uses: rustsec/audit-check@master
         with:
           token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/labeler.yml

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

.github/workflows/loom.yml

@@ -7,8 +7,14 @@ on:
 
 name: Loom
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
 env:
-  RUSTFLAGS: -Dwarnings
+  RUSTFLAGS: -Dwarnings --cfg loom --cfg tokio_unstable -C debug_assertions
+  LOOM_MAX_PREEMPTIONS: 2
+  LOOM_MAX_BRANCHES: 10000
   RUST_BACKTRACE: 1
   # Change to specific Rust release to pin
   rust_stable: stable
@@ -17,32 +23,100 @@ permissions:
   contents: read
 
 jobs:
-  loom:
-    name: loom
+  loom-sync:
+    name: loom tokio::sync
     # base_ref is null when it's not a pull request
-    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom') || (github.base_ref == null))
+    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom-sync') || (github.base_ref == null))
     runs-on: ubuntu-latest
-    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@v3
       - name: Install Rust ${{ env.rust_stable }}
-        uses: actions-rs/toolchain@v1
+        uses: dtolnay/rust-toolchain@master
         with:
             toolchain: ${{ env.rust_stable }}
-            override: true
-      - uses: Swatinem/rust-cache@v1
+      - uses: Swatinem/rust-cache@v2
+      - name: run tests
+        run: cargo test --lib --release --features full -- --nocapture sync::tests
+        working-directory: tokio
+
+  loom-time-driver:
+    name: loom time driver
+    # base_ref is null when it's not a pull request
+    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom-time-driver') || (github.base_ref == null))
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: dtolnay/rust-toolchain@master
+        with:
+            toolchain: ${{ env.rust_stable }}
+      - uses: Swatinem/rust-cache@v2
+      - name: run tests
+        run: cargo test --lib --release --features full -- --nocapture runtime::time::tests
+        working-directory: tokio
+
+  loom-current-thread:
+    name: loom current-thread scheduler
+    # base_ref is null when it's not a pull request
+    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom-current-thread') || (github.base_ref == null))
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: dtolnay/rust-toolchain@master
+        with:
+            toolchain: ${{ env.rust_stable }}
+      - uses: Swatinem/rust-cache@v2
+      - name: run tests
+        run: cargo test --lib --release --features full -- --nocapture loom_current_thread
+        working-directory: tokio
+
+  loom-multi-thread:
+    name: loom multi-thread scheduler
+    # base_ref is null when it's not a pull request
+    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom-multi-thread') || (github.base_ref == null))
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include:
+          - scope: loom_multi_thread::group_a
+          - scope: loom_multi_thread::group_b
+          - scope: loom_multi_thread::group_c
+          - scope: loom_multi_thread::group_d
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: dtolnay/rust-toolchain@master
+        with:
+            toolchain: ${{ env.rust_stable }}
+      - uses: Swatinem/rust-cache@v2
       - name: loom ${{ matrix.scope }}
-        run: cargo test --lib --release --features full -- --nocapture $SCOPE
+        run: cargo test --lib --release --features full -- $SCOPE
+        working-directory: tokio
+        env:
+          SCOPE: ${{ matrix.scope }}
+
+  loom-multi-thread-alt:
+    name: loom ALT multi-thread scheduler
+    # base_ref is null when it's not a pull request
+    if: github.repository_owner == 'tokio-rs' && (contains(github.event.pull_request.labels.*.name, 'R-loom-multi-thread-alt') || (github.base_ref == null))
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include:
+          - scope: loom_multi_thread_alt::group_a
+          - scope: loom_multi_thread_alt::group_b
+          - scope: loom_multi_thread_alt::group_c
+          - scope: loom_multi_thread_alt::group_d
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: dtolnay/rust-toolchain@master
+        with:
+            toolchain: ${{ env.rust_stable }}
+      - uses: Swatinem/rust-cache@v2
+      - name: loom ${{ matrix.scope }}
+        run: cargo test --lib --release --features full -- $SCOPE
         working-directory: tokio
         env:
-          RUSTFLAGS: --cfg loom --cfg tokio_unstable -Dwarnings
-          LOOM_MAX_PREEMPTIONS: 2
           SCOPE: ${{ matrix.scope }}

.github/workflows/pr-audit.yml

@@ -8,6 +8,10 @@ on:
     paths:
       - '**/Cargo.toml'
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
 permissions:
   contents: read
 
@@ -19,17 +23,10 @@ jobs:
       - uses: actions/checkout@v3
 
       - name: Install cargo-audit
-        uses: actions-rs/cargo@v1
-        with:
-          command: install
-          args: cargo-audit
+        run: cargo install cargo-audit
 
       - name: Generate lockfile
-        uses: actions-rs/cargo@v1
-        with:
-          command: generate-lockfile
+        run: cargo generate-lockfile
 
       - name: Audit dependencies
-        uses: actions-rs/cargo@v1
-        with:
-          command: audit
+        run: cargo audit

.github/workflows/stress-test.yml

@@ -5,6 +5,10 @@ on:
     branches:
       - master
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
 env:
   RUSTFLAGS: -Dwarnings
   RUST_BACKTRACE: 1
@@ -25,18 +29,17 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - name: Install Rust ${{ env.rust_stable }}
-        uses: actions-rs/toolchain@v1
+        uses: dtolnay/rust-toolchain@master
         with:
             toolchain: ${{ env.rust_stable }}
-            override: true
-      - uses: Swatinem/rust-cache@v1
       - name: Install Valgrind
         uses: taiki-e/install-action@valgrind
 
+      - uses: Swatinem/rust-cache@v2
       # Compiles each of the stress test examples.
       - name: Compile stress test examples
         run: cargo build -p stress-test --release --example ${{ matrix.stress-test }}
 
       # Runs each of the examples using Valgrind. Detects leaks and displays them.
       - name: Run valgrind
-        run: valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all ./target/release/examples/${{ matrix.stress-test }}
+        run: valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all --fair-sched=yes ./target/release/examples/${{ matrix.stress-test }}

.gitignore

@@ -2,3 +2,4 @@ target
 Cargo.lock
 
 .cargo/config.toml
+.cargo/config

CONTRIBUTING.md

@@ -131,8 +131,11 @@ cargo check --all-features
 cargo test --all-features
 ```
 
-Clippy must be run using the MSRV, so Tokio can avoid having to `#[allow]` new
-lints whose fixes would be incompatible with the current MSRV:
+Ideally, you should use the same version of clippy as the one used in CI
+(defined by `env.rust_clippy` in [ci.yml][ci.yml]), because newer versions
+might have new lints:
+
+[ci.yml]: .github/workflows/ci.yml
 
 <!--
 When updating this, also update:
@@ -146,7 +149,7 @@ When updating this, also update:
 -->
 
 ```
-cargo +1.49.0 clippy --all --tests --all-features
+cargo +1.65.0 clippy --all --tests --all-features
 ```
 
 When building documentation normally, the markers that list the features
@@ -170,10 +173,10 @@ command below instead:
 
 ```
 # Mac or Linux
-rustfmt --check --edition 2018 $(git ls-files '*.rs')
+rustfmt --check --edition 2021 $(git ls-files '*.rs')
 
 # Powershell
-Get-ChildItem . -Filter "*.rs" -Recurse | foreach { rustfmt --check --edition 2018 $_.FullName }
+Get-ChildItem . -Filter "*.rs" -Recurse | foreach { rustfmt --check --edition 2021 $_.FullName }
 ```
 The `--check` argument prints the things that need to be fixed. If you remove
 it, `rustfmt` will update your files locally instead.
@@ -187,7 +190,7 @@ LOOM_MAX_PREEMPTIONS=1 RUSTFLAGS="--cfg loom" \
 
 You can run miri tests with
 ```
-MIRIFLAGS="-Zmiri-disable-isolation -Zmiri-tag-raw-pointers" PROPTEST_CASES=10 \
+MIRIFLAGS="-Zmiri-disable-isolation -Zmiri-tag-raw-pointers" \
     cargo +nightly miri test --features full --lib
 ```
 
@@ -197,8 +200,22 @@ If the change being proposed alters code (as opposed to only documentation for
 example), it is either adding new functionality to Tokio or it is fixing
 existing, broken functionality. In both of these cases, the pull request should
 include one or more tests to ensure that Tokio does not regress in the future.
-There are two ways to write tests: integration tests and documentation tests
-(Tokio avoids unit tests as much as possible).
+There are two ways to write tests: [integration tests][integration-tests]
+and [documentation tests][documentation-tests].
+(Tokio avoids [unit tests][unit-tests] as much as possible).
+
+Tokio uses [conditional compilation attributes][conditional-compilation]
+throughout the codebase, to modify rustc's behavior. Code marked with such
+attributes can be enabled using RUSTFLAGS and RUSTDOCFLAGS environment
+variables. One of the most prevalent flags passed in these variables is
+the `--cfg` option. To run tests in a particular file, check first what
+options #![cfg] declaration defines for that file.
+
+For instance, to run a test marked with the 'tokio_unstable' cfg option,
+you must pass this flag to the compiler when running the test.
+```
+$ RUSTFLAGS="--cfg tokio_unstable" cargo test -p tokio --all-features --test rt_metrics
+```
 
 #### Integration tests
 
@@ -209,6 +226,31 @@ utilities available to use in tests, no matter the crate being tested.
 The best strategy for writing a new integration test is to look at existing
 integration tests in the crate and follow the style.
 
+#### Fuzz tests
+
+Some of our crates include a set of fuzz tests, this will be marked by a
+directory `fuzz`. It is a good idea to run fuzz tests after each change.
+To get started with fuzz testing you'll need to install
+[cargo-fuzz](https://github.com/rust-fuzz/cargo-fuzz).
+
+`cargo install cargo-fuzz`
+
+To list the available fuzzing harnesses you can run;
+
+```bash
+$ cd tokio
+$ cargo fuzz list
+fuzz_linked_list
+````
+
+Running a fuzz test is as simple as;
+
+`cargo fuzz run fuzz_linked_list`
+
+**NOTE**: Keep in mind that by default when running a fuzz test the fuzz
+harness will run forever and will only exit if you `ctrl-c` or it finds
+a bug.
+
 #### Documentation tests
 
 Ideally, every API has at least one [documentation test] that demonstrates how to
@@ -633,3 +675,7 @@ When releasing a new version of a crate, follow these steps:
    entry for that release version into your editor and close the window.
 
 [keep-a-changelog]: https://github.com/olivierlacan/keep-a-changelog/blob/master/CHANGELOG.md
+[unit-tests]: https://doc.rust-lang.org/rust-by-example/testing/unit_testing.html
+[integration-tests]: https://doc.rust-lang.org/rust-by-example/testing/integration_testing.html
+[documentation-tests]: https://doc.rust-lang.org/rust-by-example/testing/doc_testing.html
+[conditional-compilation]: https://doc.rust-lang.org/reference/conditional-compilation.html

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-
+resolver = "2"
 members = [
   "tokio",
   "tokio-macros",

Cross.toml

@@ -1,4 +1,5 @@
 [build.env]
 passthrough = [
     "RUSTFLAGS",
+    "RUST_BACKTRACE",
 ]

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2022 Tokio Contributors
+Copyright (c) 2023 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 = "1.22.0", features = ["full"] }
+tokio = { version = "1.35.0", features = ["full"] }
 ```
 Then, on your main.rs:
 
@@ -132,6 +132,8 @@ project.
 In addition to the crates in this repository, the Tokio project also maintains
 several other libraries, including:
 
+* [`axum`]: A web application framework that focuses on ergonomics and modularity.
+
 * [`hyper`]: A fast and correct HTTP/1.1 and HTTP/2 implementation for Rust.
 
 * [`tonic`]: A gRPC over HTTP/2 implementation focused on high performance, interoperability, and flexibility.
@@ -142,21 +144,18 @@ several other libraries, including:
 
 * [`tracing`] (formerly `tokio-trace`): A framework for application-level tracing and async-aware diagnostics.
 
-* [`rdbc`]: A Rust database connectivity library for MySQL, Postgres and SQLite.
-
-* [`mio`]: A low-level, cross-platform abstraction over OS I/O APIs that powers
-  `tokio`.
+* [`mio`]: A low-level, cross-platform abstraction over OS I/O APIs that powers `tokio`.
 
 * [`bytes`]: Utilities for working with bytes, including efficient byte buffers.
 
-* [`loom`]: A testing tool for concurrent Rust code
+* [`loom`]: A testing tool for concurrent Rust code.
 
+[`axum`]: https://github.com/tokio-rs/axum
 [`warp`]: https://github.com/seanmonstar/warp
 [`hyper`]: https://github.com/hyperium/hyper
 [`tonic`]: https://github.com/hyperium/tonic
 [`tower`]: https://github.com/tower-rs/tower
 [`loom`]: https://github.com/tokio-rs/loom
-[`rdbc`]: https://github.com/tokio-rs/rdbc
 [`tracing`]: https://github.com/tokio-rs/tracing
 [`mio`]: https://github.com/tokio-rs/mio
 [`bytes`]: https://github.com/tokio-rs/bytes
@@ -187,7 +186,21 @@ When updating this, also update:
 
 Tokio will keep a rolling MSRV (minimum supported rust version) policy of **at
 least** 6 months. When increasing the MSRV, the new Rust version must have been
-released at least six months ago. The current MSRV is 1.49.0.
+released at least six months ago. The current MSRV is 1.63.
+
+Note that the MSRV is not increased automatically, and only as part of a minor
+release. The MSRV history for past minor releases can be found below:
+
+ * 1.30 to now - Rust 1.63
+ * 1.27 to 1.29 - Rust 1.56
+ * 1.17 to 1.26 - Rust 1.49
+ * 1.15 to 1.16 - Rust 1.46
+ * 1.0 to 1.14 - Rust 1.45
+
+Note that although we try to avoid the situation where a dependency transitively
+increases the MSRV of Tokio, we do not guarantee that this does not happen.
+However, every minor release will have some set of versions of dependencies that
+works with the MSRV of that minor release.
 
 ## Release schedule
 
@@ -202,20 +215,27 @@ warrants a patch release with a fix for the bug, it will be backported and
 released as a new patch release for each LTS minor version. Our current LTS
 releases are:
 
- * `1.18.x` - LTS release until June 2023
- * `1.20.x` - LTS release until September 2023.
+ * `1.25.x` - LTS release until March 2024. (MSRV 1.49)
+ * `1.32.x` - LTS release until September 2024. (MSRV 1.63)
 
 Each LTS release will continue to receive backported fixes for at least a year.
 If you wish to use a fixed minor release in your project, we recommend that you
 use an LTS release.
 
 To use a fixed minor version, you can specify the version with a tilde. For
-example, to specify that you wish to use the newest `1.18.x` patch release, you
+example, to specify that you wish to use the newest `1.25.x` patch release, you
 can use the following dependency specification:
 ```text
-tokio = { version = "~1.18", features = [...] }
+tokio = { version = "~1.25", features = [...] }
 ```
 
+### Previous LTS releases
+
+ * `1.8.x` - LTS release until February 2022.
+ * `1.14.x` - LTS release until June 2022.
+ * `1.18.x` - LTS release until June 2023.
+ * `1.20.x` - LTS release until September 2023.
+
 ## License
 
 This project is licensed under the [MIT license].

benches/Cargo.toml

@@ -2,13 +2,17 @@
 name = "benches"
 version = "0.0.0"
 publish = false
-edition = "2018"
+edition = "2021"
+
+[features]
+test-util = ["tokio/test-util"]
 
 [dependencies]
 tokio = { version = "1.5.0", path = "../tokio", features = ["full"] }
-bencher = "0.1.5"
+criterion = "0.5.1"
 rand = "0.8"
 rand_chacha = "0.3"
+num_cpus = "1.16.0"
 
 [dev-dependencies]
 tokio-util = { version = "0.7.0", path = "../tokio-util", features = ["full"] }
@@ -27,11 +31,30 @@ name = "sync_mpsc"
 path = "sync_mpsc.rs"
 harness = false
 
+[[bench]]
+name = "sync_mpsc_oneshot"
+path = "sync_mpsc_oneshot.rs"
+harness = false
+
+[[bench]]
+name = "sync_watch"
+path = "sync_watch.rs"
+harness = false
+
+[[bench]]
+name = "rt_current_thread"
+path = "rt_current_thread.rs"
+harness = false
+
 [[bench]]
 name = "rt_multi_threaded"
 path = "rt_multi_threaded.rs"
 harness = false
 
+[[bench]]
+name = "sync_notify"
+path = "sync_notify.rs"
+harness = false
 
 [[bench]]
 name = "sync_rwlock"
@@ -57,3 +80,8 @@ harness = false
 name = "copy"
 path = "copy.rs"
 harness = false
+
+[[bench]]
+name = "time_now"
+path = "time_now.rs"
+harness = false

benches/copy.rs

@@ -1,4 +1,4 @@
-use bencher::{benchmark_group, benchmark_main, Bencher};
+use criterion::{criterion_group, criterion_main, Criterion};
 
 use rand::{Rng, SeedableRng};
 use rand_chacha::ChaCha20Rng;
@@ -174,65 +174,77 @@ fn rt() -> tokio::runtime::Runtime {
         .unwrap()
 }
 
-fn copy_mem_to_mem(b: &mut Bencher) {
+fn copy_mem_to_mem(c: &mut Criterion) {
     let rt = rt();
 
-    b.iter(|| {
-        let task = || async {
-            let mut source = repeat(0).take(SOURCE_SIZE);
-            let mut dest = Vec::new();
-            copy(&mut source, &mut dest).await.unwrap();
-        };
+    c.bench_function("copy_mem_to_mem", |b| {
+        b.iter(|| {
+            let task = || async {
+                let mut source = repeat(0).take(SOURCE_SIZE);
+                let mut dest = Vec::new();
+                copy(&mut source, &mut dest).await.unwrap();
+            };
 
-        rt.block_on(task());
-    })
+            rt.block_on(task());
+        })
+    });
 }
 
-fn copy_mem_to_slow_hdd(b: &mut Bencher) {
+fn copy_mem_to_slow_hdd(c: &mut Criterion) {
     let rt = rt();
 
-    b.iter(|| {
-        let task = || async {
-            let mut source = repeat(0).take(SOURCE_SIZE);
-            let mut dest = SlowHddWriter::new(WRITE_SERVICE_PERIOD, WRITE_BUFFER);
-            copy(&mut source, &mut dest).await.unwrap();
-        };
+    c.bench_function("copy_mem_to_slow_hdd", |b| {
+        b.iter(|| {
+            let task = || async {
+                let mut source = repeat(0).take(SOURCE_SIZE);
+                let mut dest = SlowHddWriter::new(WRITE_SERVICE_PERIOD, WRITE_BUFFER);
+                copy(&mut source, &mut dest).await.unwrap();
+            };
 
-        rt.block_on(task());
-    })
+            rt.block_on(task());
+        })
+    });
 }
 
-fn copy_chunk_to_mem(b: &mut Bencher) {
+fn copy_chunk_to_mem(c: &mut Criterion) {
     let rt = rt();
-    b.iter(|| {
-        let task = || async {
-            let mut source = ChunkReader::new(CHUNK_SIZE, READ_SERVICE_PERIOD).take(SOURCE_SIZE);
-            let mut dest = Vec::new();
-            copy(&mut source, &mut dest).await.unwrap();
-        };
 
-        rt.block_on(task());
-    })
+    c.bench_function("copy_chunk_to_mem", |b| {
+        b.iter(|| {
+            let task = || async {
+                let mut source =
+                    ChunkReader::new(CHUNK_SIZE, READ_SERVICE_PERIOD).take(SOURCE_SIZE);
+                let mut dest = Vec::new();
+                copy(&mut source, &mut dest).await.unwrap();
+            };
+
+            rt.block_on(task());
+        })
+    });
 }
 
-fn copy_chunk_to_slow_hdd(b: &mut Bencher) {
+fn copy_chunk_to_slow_hdd(c: &mut Criterion) {
     let rt = rt();
-    b.iter(|| {
-        let task = || async {
-            let mut source = ChunkReader::new(CHUNK_SIZE, READ_SERVICE_PERIOD).take(SOURCE_SIZE);
-            let mut dest = SlowHddWriter::new(WRITE_SERVICE_PERIOD, WRITE_BUFFER);
-            copy(&mut source, &mut dest).await.unwrap();
-        };
 
-        rt.block_on(task());
-    })
+    c.bench_function("copy_chunk_to_slow_hdd", |b| {
+        b.iter(|| {
+            let task = || async {
+                let mut source =
+                    ChunkReader::new(CHUNK_SIZE, READ_SERVICE_PERIOD).take(SOURCE_SIZE);
+                let mut dest = SlowHddWriter::new(WRITE_SERVICE_PERIOD, WRITE_BUFFER);
+                copy(&mut source, &mut dest).await.unwrap();
+            };
+
+            rt.block_on(task());
+        })
+    });
 }
 
-benchmark_group!(
+criterion_group!(
     copy_bench,
     copy_mem_to_mem,
     copy_mem_to_slow_hdd,
     copy_chunk_to_mem,
     copy_chunk_to_slow_hdd,
 );
-benchmark_main!(copy_bench);
+criterion_main!(copy_bench);

benches/fs.rs

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

benches/rt_current_thread.rs

@@ -0,0 +1,89 @@
+//! 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.
+
+use tokio::runtime::{self, Runtime};
+
+use criterion::{criterion_group, criterion_main, Criterion};
+
+const NUM_SPAWN: usize = 1_000;
+
+fn spawn_many_local(c: &mut Criterion) {
+    let rt = rt();
+    let mut handles = Vec::with_capacity(NUM_SPAWN);
+
+    c.bench_function("spawn_many_local", |b| {
+        b.iter(|| {
+            rt.block_on(async {
+                for _ in 0..NUM_SPAWN {
+                    handles.push(tokio::spawn(async move {}));
+                }
+
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
+    });
+}
+
+fn spawn_many_remote_idle(c: &mut Criterion) {
+    let rt = rt();
+    let rt_handle = rt.handle();
+    let mut handles = Vec::with_capacity(NUM_SPAWN);
+
+    c.bench_function("spawn_many_remote_idle", |b| {
+        b.iter(|| {
+            for _ in 0..NUM_SPAWN {
+                handles.push(rt_handle.spawn(async {}));
+            }
+
+            rt.block_on(async {
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
+    });
+}
+
+fn spawn_many_remote_busy(c: &mut Criterion) {
+    let rt = rt();
+    let rt_handle = rt.handle();
+    let mut handles = Vec::with_capacity(NUM_SPAWN);
+
+    rt.spawn(async {
+        fn iter() {
+            tokio::spawn(async { iter() });
+        }
+
+        iter()
+    });
+
+    c.bench_function("spawn_many_remote_busy", |b| {
+        b.iter(|| {
+            for _ in 0..NUM_SPAWN {
+                handles.push(rt_handle.spawn(async {}));
+            }
+
+            rt.block_on(async {
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
+    });
+}
+
+fn rt() -> Runtime {
+    runtime::Builder::new_current_thread().build().unwrap()
+}
+
+criterion_group!(
+    scheduler,
+    spawn_many_local,
+    spawn_many_remote_idle,
+    spawn_many_remote_busy
+);
+
+criterion_main!(scheduler);

benches/rt_multi_threaded.rs

@@ -5,67 +5,173 @@
 use tokio::runtime::{self, Runtime};
 use tokio::sync::oneshot;
 
-use bencher::{benchmark_group, benchmark_main, Bencher};
-use std::sync::atomic::AtomicUsize;
 use std::sync::atomic::Ordering::Relaxed;
+use std::sync::atomic::{AtomicBool, AtomicUsize};
 use std::sync::{mpsc, Arc};
+use std::time::{Duration, Instant};
 
-fn spawn_many(b: &mut Bencher) {
-    const NUM_SPAWN: usize = 10_000;
+use criterion::{criterion_group, criterion_main, Criterion};
 
+const NUM_WORKERS: usize = 4;
+const NUM_SPAWN: usize = 10_000;
+const STALL_DUR: Duration = Duration::from_micros(10);
+
+fn spawn_many_local(c: &mut Criterion) {
     let rt = rt();
 
     let (tx, rx) = mpsc::sync_channel(1000);
     let rem = Arc::new(AtomicUsize::new(0));
 
-    b.iter(|| {
-        rem.store(NUM_SPAWN, Relaxed);
+    c.bench_function("spawn_many_local", |b| {
+        b.iter(|| {
+            rem.store(NUM_SPAWN, Relaxed);
 
-        rt.block_on(async {
-            for _ in 0..NUM_SPAWN {
-                let tx = tx.clone();
-                let rem = rem.clone();
+            rt.block_on(async {
+                for _ in 0..NUM_SPAWN {
+                    let tx = tx.clone();
+                    let rem = rem.clone();
 
-                tokio::spawn(async move {
-                    if 1 == rem.fetch_sub(1, Relaxed) {
-                        tx.send(()).unwrap();
-                    }
-                });
-            }
+                    tokio::spawn(async move {
+                        if 1 == rem.fetch_sub(1, Relaxed) {
+                            tx.send(()).unwrap();
+                        }
+                    });
+                }
 
-            let _ = rx.recv().unwrap();
-        });
+                let _ = rx.recv().unwrap();
+            });
+        })
     });
 }
 
-fn yield_many(b: &mut Bencher) {
+fn spawn_many_remote_idle(c: &mut Criterion) {
+    let rt = rt();
+
+    let mut handles = Vec::with_capacity(NUM_SPAWN);
+
+    c.bench_function("spawn_many_remote_idle", |b| {
+        b.iter(|| {
+            for _ in 0..NUM_SPAWN {
+                handles.push(rt.spawn(async {}));
+            }
+
+            rt.block_on(async {
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
+    });
+}
+
+// The runtime is busy with tasks that consume CPU time and yield. Yielding is a
+// lower notification priority than spawning / regular notification.
+fn spawn_many_remote_busy1(c: &mut Criterion) {
+    let rt = rt();
+    let rt_handle = rt.handle();
+    let mut handles = Vec::with_capacity(NUM_SPAWN);
+    let flag = Arc::new(AtomicBool::new(true));
+
+    // Spawn some tasks to keep the runtimes busy
+    for _ in 0..(2 * NUM_WORKERS) {
+        let flag = flag.clone();
+        rt.spawn(async move {
+            while flag.load(Relaxed) {
+                tokio::task::yield_now().await;
+                stall();
+            }
+        });
+    }
+
+    c.bench_function("spawn_many_remote_busy1", |b| {
+        b.iter(|| {
+            for _ in 0..NUM_SPAWN {
+                handles.push(rt_handle.spawn(async {}));
+            }
+
+            rt.block_on(async {
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
+    });
+
+    flag.store(false, Relaxed);
+}
+
+// The runtime is busy with tasks that consume CPU time and spawn new high-CPU
+// tasks. Spawning goes via a higher notification priority than yielding.
+fn spawn_many_remote_busy2(c: &mut Criterion) {
+    const NUM_SPAWN: usize = 1_000;
+
+    let rt = rt();
+    let rt_handle = rt.handle();
+    let mut handles = Vec::with_capacity(NUM_SPAWN);
+    let flag = Arc::new(AtomicBool::new(true));
+
+    // Spawn some tasks to keep the runtimes busy
+    for _ in 0..(NUM_WORKERS) {
+        let flag = flag.clone();
+        fn iter(flag: Arc<AtomicBool>) {
+            tokio::spawn(async {
+                if flag.load(Relaxed) {
+                    stall();
+                    iter(flag);
+                }
+            });
+        }
+        rt.spawn(async {
+            iter(flag);
+        });
+    }
+
+    c.bench_function("spawn_many_remote_busy2", |b| {
+        b.iter(|| {
+            for _ in 0..NUM_SPAWN {
+                handles.push(rt_handle.spawn(async {}));
+            }
+
+            rt.block_on(async {
+                for handle in handles.drain(..) {
+                    handle.await.unwrap();
+                }
+            });
+        })
+    });
+
+    flag.store(false, Relaxed);
+}
+
+fn yield_many(c: &mut Criterion) {
     const NUM_YIELD: usize = 1_000;
     const TASKS: usize = 200;
 
-    let rt = rt();
+    c.bench_function("yield_many", |b| {
+        let rt = rt();
+        let (tx, rx) = mpsc::sync_channel(TASKS);
 
-    let (tx, rx) = mpsc::sync_channel(TASKS);
+        b.iter(move || {
+            for _ in 0..TASKS {
+                let tx = tx.clone();
 
-    b.iter(move || {
-        for _ in 0..TASKS {
-            let tx = tx.clone();
+                rt.spawn(async move {
+                    for _ in 0..NUM_YIELD {
+                        tokio::task::yield_now().await;
+                    }
 
-            rt.spawn(async move {
-                for _ in 0..NUM_YIELD {
-                    tokio::task::yield_now().await;
-                }
+                    tx.send(()).unwrap();
+                });
+            }
 
-                tx.send(()).unwrap();
-            });
-        }
-
-        for _ in 0..TASKS {
-            let _ = rx.recv().unwrap();
-        }
+            for _ in 0..TASKS {
+                let _ = rx.recv().unwrap();
+            }
+        })
     });
 }
 
-fn ping_pong(b: &mut Bencher) {
+fn ping_pong(c: &mut Criterion) {
     const NUM_PINGS: usize = 1_000;
 
     let rt = rt();
@@ -73,46 +179,46 @@ fn ping_pong(b: &mut Bencher) {
     let (done_tx, done_rx) = mpsc::sync_channel(1000);
     let rem = Arc::new(AtomicUsize::new(0));
 
-    b.iter(|| {
-        let done_tx = done_tx.clone();
-        let rem = rem.clone();
-        rem.store(NUM_PINGS, Relaxed);
+    c.bench_function("ping_pong", |b| {
+        b.iter(|| {
+            let done_tx = done_tx.clone();
+            let rem = rem.clone();
+            rem.store(NUM_PINGS, Relaxed);
 
-        rt.block_on(async {
-            tokio::spawn(async move {
-                for _ in 0..NUM_PINGS {
-                    let rem = rem.clone();
-                    let done_tx = done_tx.clone();
-
-                    tokio::spawn(async move {
-                        let (tx1, rx1) = oneshot::channel();
-                        let (tx2, rx2) = oneshot::channel();
+            rt.block_on(async {
+                tokio::spawn(async move {
+                    for _ in 0..NUM_PINGS {
+                        let rem = rem.clone();
+                        let done_tx = done_tx.clone();
 
                         tokio::spawn(async move {
-                            rx1.await.unwrap();
-                            tx2.send(()).unwrap();
+                            let (tx1, rx1) = oneshot::channel();
+                            let (tx2, rx2) = oneshot::channel();
+
+                            tokio::spawn(async move {
+                                rx1.await.unwrap();
+                                tx2.send(()).unwrap();
+                            });
+
+                            tx1.send(()).unwrap();
+                            rx2.await.unwrap();
+
+                            if 1 == rem.fetch_sub(1, Relaxed) {
+                                done_tx.send(()).unwrap();
+                            }
                         });
+                    }
+                });
 
-                        tx1.send(()).unwrap();
-                        rx2.await.unwrap();
-
-                        if 1 == rem.fetch_sub(1, Relaxed) {
-                            done_tx.send(()).unwrap();
-                        }
-                    });
-                }
+                done_rx.recv().unwrap();
             });
-
-            done_rx.recv().unwrap();
-        });
+        })
     });
 }
 
-fn chained_spawn(b: &mut Bencher) {
+fn chained_spawn(c: &mut Criterion) {
     const ITER: usize = 1_000;
 
-    let rt = rt();
-
     fn iter(done_tx: mpsc::SyncSender<()>, n: usize) {
         if n == 0 {
             done_tx.send(()).unwrap();
@@ -123,29 +229,48 @@ fn chained_spawn(b: &mut Bencher) {
         }
     }
 
-    let (done_tx, done_rx) = mpsc::sync_channel(1000);
+    c.bench_function("chained_spawn", |b| {
+        let rt = rt();
+        let (done_tx, done_rx) = mpsc::sync_channel(1000);
 
-    b.iter(move || {
-        let done_tx = done_tx.clone();
+        b.iter(move || {
+            let done_tx = done_tx.clone();
 
-        rt.block_on(async {
-            tokio::spawn(async move {
-                iter(done_tx, ITER);
+            rt.block_on(async {
+                tokio::spawn(async move {
+                    iter(done_tx, ITER);
+                });
+
+                done_rx.recv().unwrap();
             });
-
-            done_rx.recv().unwrap();
-        });
+        })
     });
 }
 
 fn rt() -> Runtime {
     runtime::Builder::new_multi_thread()
-        .worker_threads(4)
+        .worker_threads(NUM_WORKERS)
         .enable_all()
         .build()
         .unwrap()
 }
 
-benchmark_group!(scheduler, spawn_many, ping_pong, yield_many, chained_spawn,);
+fn stall() {
+    let now = Instant::now();
+    while now.elapsed() < STALL_DUR {
+        std::thread::yield_now();
+    }
+}
 
-benchmark_main!(scheduler);
+criterion_group!(
+    scheduler,
+    spawn_many_local,
+    spawn_many_remote_idle,
+    spawn_many_remote_busy1,
+    spawn_many_remote_busy2,
+    ping_pong,
+    yield_many,
+    chained_spawn,
+);
+
+criterion_main!(scheduler);

benches/signal.rs

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

benches/spawn.rs

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

benches/sync_mpsc.rs

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

benches/sync_mpsc_oneshot.rs

@@ -0,0 +1,56 @@
+use tokio::{
+    runtime::Runtime,
+    sync::{mpsc, oneshot},
+};
+
+use criterion::{criterion_group, criterion_main, Criterion};
+
+fn request_reply_current_thread(c: &mut Criterion) {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .build()
+        .unwrap();
+
+    request_reply(c, rt);
+}
+
+fn request_reply_multi_threaded(c: &mut Criterion) {
+    let rt = tokio::runtime::Builder::new_multi_thread()
+        .worker_threads(1)
+        .build()
+        .unwrap();
+
+    request_reply(c, rt);
+}
+
+fn request_reply(b: &mut Criterion, rt: Runtime) {
+    let tx = rt.block_on(async move {
+        let (tx, mut rx) = mpsc::channel::<oneshot::Sender<()>>(10);
+        tokio::spawn(async move {
+            while let Some(reply) = rx.recv().await {
+                reply.send(()).unwrap();
+            }
+        });
+        tx
+    });
+
+    b.bench_function("request_reply", |b| {
+        b.iter(|| {
+            let task_tx = tx.clone();
+            rt.block_on(async move {
+                for _ in 0..1_000 {
+                    let (o_tx, o_rx) = oneshot::channel();
+                    task_tx.send(o_tx).await.unwrap();
+                    let _ = o_rx.await;
+                }
+            })
+        })
+    });
+}
+
+criterion_group!(
+    sync_mpsc_oneshot_group,
+    request_reply_current_thread,
+    request_reply_multi_threaded,
+);
+
+criterion_main!(sync_mpsc_oneshot_group);

benches/sync_notify.rs

@@ -0,0 +1,104 @@
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+
+use tokio::sync::Notify;
+
+use criterion::measurement::WallTime;
+use criterion::{criterion_group, criterion_main, BenchmarkGroup, Criterion};
+
+fn rt() -> tokio::runtime::Runtime {
+    tokio::runtime::Builder::new_multi_thread()
+        .worker_threads(6)
+        .build()
+        .unwrap()
+}
+
+fn notify_waiters<const N_WAITERS: usize>(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
+    let notify = Arc::new(Notify::new());
+    let counter = Arc::new(AtomicUsize::new(0));
+    for _ in 0..N_WAITERS {
+        rt.spawn({
+            let notify = notify.clone();
+            let counter = counter.clone();
+            async move {
+                loop {
+                    notify.notified().await;
+                    counter.fetch_add(1, Ordering::Relaxed);
+                }
+            }
+        });
+    }
+
+    const N_ITERS: usize = 500;
+    g.bench_function(N_WAITERS.to_string(), |b| {
+        b.iter(|| {
+            counter.store(0, Ordering::Relaxed);
+            loop {
+                notify.notify_waiters();
+                if counter.load(Ordering::Relaxed) >= N_ITERS {
+                    break;
+                }
+            }
+        })
+    });
+}
+
+fn notify_one<const N_WAITERS: usize>(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
+    let notify = Arc::new(Notify::new());
+    let counter = Arc::new(AtomicUsize::new(0));
+    for _ in 0..N_WAITERS {
+        rt.spawn({
+            let notify = notify.clone();
+            let counter = counter.clone();
+            async move {
+                loop {
+                    notify.notified().await;
+                    counter.fetch_add(1, Ordering::Relaxed);
+                }
+            }
+        });
+    }
+
+    const N_ITERS: usize = 500;
+    g.bench_function(N_WAITERS.to_string(), |b| {
+        b.iter(|| {
+            counter.store(0, Ordering::Relaxed);
+            loop {
+                notify.notify_one();
+                if counter.load(Ordering::Relaxed) >= N_ITERS {
+                    break;
+                }
+            }
+        })
+    });
+}
+
+fn bench_notify_one(c: &mut Criterion) {
+    let mut group = c.benchmark_group("notify_one");
+    notify_one::<10>(&mut group);
+    notify_one::<50>(&mut group);
+    notify_one::<100>(&mut group);
+    notify_one::<200>(&mut group);
+    notify_one::<500>(&mut group);
+    group.finish();
+}
+
+fn bench_notify_waiters(c: &mut Criterion) {
+    let mut group = c.benchmark_group("notify_waiters");
+    notify_waiters::<10>(&mut group);
+    notify_waiters::<50>(&mut group);
+    notify_waiters::<100>(&mut group);
+    notify_waiters::<200>(&mut group);
+    notify_waiters::<500>(&mut group);
+    group.finish();
+}
+
+criterion_group!(
+    notify_waiters_simple,
+    bench_notify_one,
+    bench_notify_waiters
+);
+
+criterion_main!(notify_waiters_simple);

benches/sync_rwlock.rs

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

benches/sync_semaphore.rs

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

benches/sync_watch.rs

@@ -0,0 +1,85 @@
+use rand::prelude::*;
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::Arc;
+use tokio::sync::{watch, Notify};
+
+use criterion::measurement::WallTime;
+use criterion::{black_box, criterion_group, criterion_main, BenchmarkGroup, Criterion};
+
+fn rt() -> tokio::runtime::Runtime {
+    tokio::runtime::Builder::new_multi_thread()
+        .worker_threads(6)
+        .build()
+        .unwrap()
+}
+
+fn do_work(rng: &mut impl RngCore) -> u32 {
+    use std::fmt::Write;
+    let mut message = String::new();
+    for i in 1..=10 {
+        let _ = write!(&mut message, " {i}={}", rng.gen::<f64>());
+    }
+    message
+        .as_bytes()
+        .iter()
+        .map(|&c| c as u32)
+        .fold(0, u32::wrapping_add)
+}
+
+fn contention_resubscribe<const N_TASKS: usize>(g: &mut BenchmarkGroup<WallTime>) {
+    let rt = rt();
+    let (snd, _) = watch::channel(0i32);
+    let snd = Arc::new(snd);
+    let wg = Arc::new((AtomicU64::new(0), Notify::new()));
+    for n in 0..N_TASKS {
+        let mut rcv = snd.subscribe();
+        let wg = wg.clone();
+        let mut rng = rand::rngs::StdRng::seed_from_u64(n as u64);
+        rt.spawn(async move {
+            while rcv.changed().await.is_ok() {
+                let _ = *rcv.borrow(); // contend on rwlock
+                let r = do_work(&mut rng);
+                let _ = black_box(r);
+                if wg.0.fetch_sub(1, Ordering::Release) == 1 {
+                    wg.1.notify_one();
+                }
+            }
+        });
+    }
+
+    const N_ITERS: usize = 100;
+    g.bench_function(N_TASKS.to_string(), |b| {
+        b.iter(|| {
+            rt.block_on({
+                let snd = snd.clone();
+                let wg = wg.clone();
+                async move {
+                    tokio::spawn(async move {
+                        for _ in 0..N_ITERS {
+                            assert_eq!(wg.0.fetch_add(N_TASKS as u64, Ordering::Relaxed), 0);
+                            let _ = snd.send(black_box(42));
+                            while wg.0.load(Ordering::Acquire) > 0 {
+                                wg.1.notified().await;
+                            }
+                        }
+                    })
+                    .await
+                    .unwrap();
+                }
+            });
+        })
+    });
+}
+
+fn bench_contention_resubscribe(c: &mut Criterion) {
+    let mut group = c.benchmark_group("contention_resubscribe");
+    contention_resubscribe::<10>(&mut group);
+    contention_resubscribe::<100>(&mut group);
+    contention_resubscribe::<500>(&mut group);
+    contention_resubscribe::<1000>(&mut group);
+    group.finish();
+}
+
+criterion_group!(contention, bench_contention_resubscribe);
+
+criterion_main!(contention);

benches/time_now.rs

@@ -0,0 +1,24 @@
+//! Benchmark spawning a task onto the basic and threaded Tokio executors.
+//! This essentially measure the time to enqueue a task in the local and remote
+//! case.
+
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+
+fn time_now_current_thread(c: &mut Criterion) {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_time()
+        .build()
+        .unwrap();
+
+    c.bench_function("time_now_current_thread", |b| {
+        b.iter(|| {
+            rt.block_on(async {
+                black_box(tokio::time::Instant::now());
+            })
+        })
+    });
+}
+
+criterion_group!(time_now, time_now_current_thread);
+
+criterion_main!(time_now);

bin/publish

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

bin/update-doc

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

examples/Cargo.toml

@@ -2,7 +2,7 @@
 name = "examples"
 version = "0.0.0"
 publish = false
-edition = "2018"
+edition = "2021"
 
 # If you copy one of the examples into a new project, you should be using
 # [dependencies] instead, and delete the **path**.
@@ -25,7 +25,7 @@ once_cell = "1.5.2"
 rand = "0.8.3"
 
 [target.'cfg(windows)'.dev-dependencies.windows-sys]
-version = "0.42.0"
+version = "0.48"
 
 [[example]]
 name = "chat"
@@ -90,3 +90,7 @@ path = "named-pipe-ready.rs"
 [[example]]
 name = "named-pipe-multi-client"
 path = "named-pipe-multi-client.rs"
+
+[[example]]
+name = "dump"
+path = "dump.rs"

examples/dump.rs

@@ -0,0 +1,90 @@
+//! This example demonstrates tokio's experimental task dumping functionality.
+//! This application deadlocks. Input CTRL+C to display traces of each task, or
+//! input CTRL+C twice within 1 second to quit.
+
+#[cfg(all(
+    tokio_unstable,
+    tokio_taskdump,
+    target_os = "linux",
+    any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+))]
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    use std::sync::Arc;
+    use tokio::sync::Barrier;
+
+    #[inline(never)]
+    async fn a(barrier: Arc<Barrier>) {
+        b(barrier).await
+    }
+
+    #[inline(never)]
+    async fn b(barrier: Arc<Barrier>) {
+        c(barrier).await
+    }
+
+    #[inline(never)]
+    async fn c(barrier: Arc<Barrier>) {
+        barrier.wait().await;
+    }
+
+    // Prints a task dump upon receipt of CTRL+C, or returns if CTRL+C is
+    // inputted twice within a second.
+    async fn dump_or_quit() {
+        use tokio::time::{timeout, Duration, Instant};
+        let handle = tokio::runtime::Handle::current();
+        let mut last_signal: Option<Instant> = None;
+        // wait for CTRL+C
+        while let Ok(_) = tokio::signal::ctrl_c().await {
+            // exit if a CTRL+C is inputted twice within 1 second
+            if let Some(time_since_last_signal) = last_signal.map(|i| i.elapsed()) {
+                if time_since_last_signal < Duration::from_secs(1) {
+                    return;
+                }
+            }
+            last_signal = Some(Instant::now());
+
+            // capture a dump, and print each trace
+            println!("{:-<80}", "");
+            if let Ok(dump) = timeout(Duration::from_secs(2), handle.dump()).await {
+                for (i, task) in dump.tasks().iter().enumerate() {
+                    let trace = task.trace();
+                    println!("TASK {i}:");
+                    println!("{trace}\n");
+                }
+            } else {
+                println!("Task dumping timed out. Use a native debugger (like gdb) to debug the deadlock.");
+            }
+            println!("{:-<80}", "");
+            println!("Input CTRL+C twice within 1 second to exit.");
+        }
+    }
+
+    println!("This program has a deadlock.");
+    println!("Input CTRL+C to print a task dump.");
+    println!("Input CTRL+C twice within 1 second to exit.");
+
+    // oops! this barrier waits for one more task than will ever come.
+    let barrier = Arc::new(Barrier::new(3));
+
+    let task_1 = tokio::spawn(a(barrier.clone()));
+    let task_2 = tokio::spawn(a(barrier));
+
+    tokio::select!(
+        _ = dump_or_quit() => {},
+        _ = task_1 => {},
+        _ = task_2 => {},
+    );
+
+    Ok(())
+}
+
+#[cfg(not(all(
+    tokio_unstable,
+    tokio_taskdump,
+    target_os = "linux",
+    any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+)))]
+fn main() {
+    println!("task dumps are not available")
+}

examples/proxy.rs

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

examples/tinyhttp.rs

@@ -180,8 +180,11 @@ impl Decoder for Http {
                 headers[i] = Some((k, v));
             }
 
+            let method = http::Method::try_from(r.method.unwrap())
+                .map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
+
             (
-                toslice(r.method.unwrap().as_bytes()),
+                method,
                 toslice(r.path.unwrap().as_bytes()),
                 r.version.unwrap(),
                 amt,
@@ -195,7 +198,7 @@ impl Decoder for Http {
         }
         let data = src.split_to(amt).freeze();
         let mut ret = Request::builder();
-        ret = ret.method(&data[method.0..method.1]);
+        ret = ret.method(method);
         let s = data.slice(path.0..path.1);
         let s = unsafe { String::from_utf8_unchecked(Vec::from(s.as_ref())) };
         ret = ret.uri(s);

netlify.toml

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

stress-test/Cargo.toml

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

tests-build/Cargo.toml

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

tests-build/tests/fail/macros_invalid_input.rs

@@ -36,13 +36,10 @@ async fn test_worker_threads_not_int() {}
 async fn test_worker_threads_and_current_thread() {}
 
 #[tokio::test(crate = 456)]
-async fn test_crate_not_ident_int() {}
+async fn test_crate_not_path_int() {}
 
 #[tokio::test(crate = "456")]
-async fn test_crate_not_ident_invalid() {}
-
-#[tokio::test(crate = "abc::edf")]
-async fn test_crate_not_ident_path() {}
+async fn test_crate_not_path_invalid() {}
 
 #[tokio::test]
 #[test]

tests-build/tests/fail/macros_invalid_input.stderr

@@ -64,34 +64,28 @@ error: The `worker_threads` option requires the `multi_thread` runtime flavor. U
 35 | #[tokio::test(flavor = "current_thread", worker_threads = 4)]
    |                                                           ^
 
-error: Failed to parse value of `crate` as ident.
+error: Failed to parse value of `crate` as path.
   --> $DIR/macros_invalid_input.rs:38:23
    |
 38 | #[tokio::test(crate = 456)]
    |                       ^^^
 
-error: Failed to parse value of `crate` as ident: "456"
+error: Failed to parse value of `crate` as path: "456"
   --> $DIR/macros_invalid_input.rs:41:23
    |
 41 | #[tokio::test(crate = "456")]
    |                       ^^^^^
 
-error: Failed to parse value of `crate` as ident: "abc::edf"
-  --> $DIR/macros_invalid_input.rs:44:23
-   |
-44 | #[tokio::test(crate = "abc::edf")]
-   |                       ^^^^^^^^^^
-
 error: second test attribute is supplied
-  --> $DIR/macros_invalid_input.rs:48:1
+  --> $DIR/macros_invalid_input.rs:45:1
    |
-48 | #[test]
+45 | #[test]
    | ^^^^^^^
 
 error: duplicated attribute
-  --> $DIR/macros_invalid_input.rs:48:1
+  --> $DIR/macros_invalid_input.rs:45:1
    |
-48 | #[test]
+45 | #[test]
    | ^^^^^^^
    |
 note: the lint level is defined here

tests-build/tests/fail/macros_type_mismatch.stderr

@@ -1,33 +1,33 @@
 error[E0308]: mismatched types
- --> $DIR/macros_type_mismatch.rs:5:5
+ --> tests/fail/macros_type_mismatch.rs:5:5
   |
 4 | async fn missing_semicolon_or_return_type() {
   |                                             - help: a return type might be missing here: `-> _`
 5 |     Ok(())
-  |     ^^^^^^ expected `()`, found enum `Result`
+  |     ^^^^^^ expected `()`, found `Result<(), _>`
   |
   = note: expected unit type `()`
                   found enum `Result<(), _>`
 
 error[E0308]: mismatched types
-  --> $DIR/macros_type_mismatch.rs:10:5
+  --> tests/fail/macros_type_mismatch.rs:10:5
    |
 9  | async fn missing_return_type() {
    |                                - help: a return type might be missing here: `-> _`
 10 |     return Ok(());
-   |     ^^^^^^^^^^^^^^ expected `()`, found enum `Result`
+   |     ^^^^^^^^^^^^^^ expected `()`, found `Result<(), _>`
    |
    = note: expected unit type `()`
                    found enum `Result<(), _>`
 
 error[E0308]: mismatched types
-  --> $DIR/macros_type_mismatch.rs:23:5
+  --> tests/fail/macros_type_mismatch.rs:23:5
    |
 14 | async fn extra_semicolon() -> Result<(), ()> {
    |                               -------------- expected `Result<(), ()>` because of return type
 ...
 23 |     Ok(());
-   |     ^^^^^^^ expected enum `Result`, found `()`
+   |     ^^^^^^^ expected `Result<(), ()>`, found `()`
    |
    = note:   expected enum `Result<(), ()>`
            found unit type `()`
@@ -38,7 +38,7 @@ help: try adding an expression at the end of the block
    |
 
 error[E0308]: mismatched types
-  --> $DIR/macros_type_mismatch.rs:32:5
+  --> tests/fail/macros_type_mismatch.rs:32:5
    |
 30 | async fn issue_4635() {
    |                       - help: try adding a return type: `-> i32`

tests-integration/Cargo.toml

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

tests-integration/tests/process_stdio.rs

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

tokio-macros/CHANGELOG.md

@@ -1,3 +1,34 @@
+# 2.2.0 (November 19th, 2023)
+
+### Changed
+
+- use `::core` qualified imports instead of `::std` inside `tokio::test` macro ([#5973])
+
+[#5973]: https://github.com/tokio-rs/tokio/pull/5973
+
+# 2.1.0 (April 25th, 2023)
+
+- macros: fix typo in `#[tokio::test]` docs ([#5636])
+- macros: make entrypoints more efficient ([#5621])
+
+[#5621]: https://github.com/tokio-rs/tokio/pull/5621
+[#5636]: https://github.com/tokio-rs/tokio/pull/5636
+
+# 2.0.0 (March 24th, 2023)
+
+This major release updates the dependency on the syn crate to 2.0.0, and
+increases the MSRV to 1.56.
+
+As part of this release, we are adopting a policy of depending on a specific minor
+release of tokio-macros. This prevents Tokio from being able to pull in many different
+versions of tokio-macros.
+
+- macros: update `syn` ([#5572])
+- macros: accept path as crate rename ([#5557])
+
+[#5572]: https://github.com/tokio-rs/tokio/pull/5572
+[#5557]: https://github.com/tokio-rs/tokio/pull/5557
+
 # 1.8.2 (November 30th, 2022)
 
 - fix a regression introduced in 1.8.1 ([#5244])

tokio-macros/Cargo.toml

@@ -4,9 +4,9 @@ name = "tokio-macros"
 # - Remove path dependencies
 # - Update CHANGELOG.md.
 # - Create "tokio-macros-1.x.y" git tag.
-version = "1.8.2"
-edition = "2018"
-rust-version = "1.49"
+version = "2.2.0"
+edition = "2021"
+rust-version = "1.63"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
@@ -22,9 +22,9 @@ proc-macro = true
 [features]
 
 [dependencies]
-proc-macro2 = "1.0.7"
+proc-macro2 = "1.0.60"
 quote = "1"
-syn = { version = "1.0.56", features = ["full"] }
+syn = { version = "2.0", features = ["full"] }
 
 [dev-dependencies]
 tokio = { version = "1.0.0", path = "../tokio", features = ["full"] }

tokio-macros/LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2022 Tokio Contributors
+Copyright (c) 2023 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

@@ -1,10 +1,10 @@
-use proc_macro::TokenStream;
-use proc_macro2::{Ident, Span};
+use proc_macro2::{Span, TokenStream, TokenTree};
 use quote::{quote, quote_spanned, ToTokens};
-use syn::parse::Parser;
+use syn::parse::{Parse, ParseStream, Parser};
+use syn::{braced, Attribute, Ident, Path, Signature, Visibility};
 
 // syn::AttributeArgs does not implement syn::Parse
-type AttributeArgs = syn::punctuated::Punctuated<syn::NestedMeta, syn::Token![,]>;
+type AttributeArgs = syn::punctuated::Punctuated<syn::Meta, syn::Token![,]>;
 
 #[derive(Clone, Copy, PartialEq)]
 enum RuntimeFlavor {
@@ -29,7 +29,7 @@ struct FinalConfig {
     flavor: RuntimeFlavor,
     worker_threads: Option<usize>,
     start_paused: Option<bool>,
-    crate_name: Option<String>,
+    crate_name: Option<Path>,
 }
 
 /// Config used in case of the attribute not being able to build a valid config
@@ -47,7 +47,7 @@ struct Configuration {
     worker_threads: Option<(usize, Span)>,
     start_paused: Option<(bool, Span)>,
     is_test: bool,
-    crate_name: Option<String>,
+    crate_name: Option<Path>,
 }
 
 impl Configuration {
@@ -112,8 +112,8 @@ impl Configuration {
         if self.crate_name.is_some() {
             return Err(syn::Error::new(span, "`crate` set multiple times."));
         }
-        let name_ident = parse_ident(name, span, "crate")?;
-        self.crate_name = Some(name_ident.to_string());
+        let name_path = parse_path(name, span, "crate")?;
+        self.crate_name = Some(name_path);
         Ok(())
     }
 
@@ -126,22 +126,22 @@ impl Configuration {
     }
 
     fn build(&self) -> Result<FinalConfig, syn::Error> {
-        let flavor = self.flavor.unwrap_or(self.default_flavor);
-        use RuntimeFlavor::*;
+        use RuntimeFlavor as F;
 
+        let flavor = self.flavor.unwrap_or(self.default_flavor);
         let worker_threads = match (flavor, self.worker_threads) {
-            (CurrentThread, Some((_, worker_threads_span))) => {
+            (F::CurrentThread, Some((_, worker_threads_span))) => {
                 let msg = format!(
                     "The `worker_threads` option requires the `multi_thread` runtime flavor. Use `#[{}(flavor = \"multi_thread\")]`",
                     self.macro_name(),
                 );
                 return Err(syn::Error::new(worker_threads_span, msg));
             }
-            (CurrentThread, None) => None,
-            (Threaded, worker_threads) if self.rt_multi_thread_available => {
+            (F::CurrentThread, None) => None,
+            (F::Threaded, worker_threads) if self.rt_multi_thread_available => {
                 worker_threads.map(|(val, _span)| val)
             }
-            (Threaded, _) => {
+            (F::Threaded, _) => {
                 let msg = if self.flavor.is_none() {
                     "The default runtime flavor is `multi_thread`, but the `rt-multi-thread` feature is disabled."
                 } else {
@@ -152,14 +152,14 @@ impl Configuration {
         };
 
         let start_paused = match (flavor, self.start_paused) {
-            (Threaded, Some((_, start_paused_span))) => {
+            (F::Threaded, Some((_, start_paused_span))) => {
                 let msg = format!(
                     "The `start_paused` option requires the `current_thread` runtime flavor. Use `#[{}(flavor = \"current_thread\")]`",
                     self.macro_name(),
                 );
                 return Err(syn::Error::new(start_paused_span, msg));
             }
-            (CurrentThread, Some((start_paused, _))) => Some(start_paused),
+            (F::CurrentThread, Some((start_paused, _))) => Some(start_paused),
             (_, None) => None,
         };
 
@@ -199,23 +199,22 @@ fn parse_string(int: syn::Lit, span: Span, field: &str) -> Result<String, syn::E
     }
 }
 
-fn parse_ident(lit: syn::Lit, span: Span, field: &str) -> Result<Ident, syn::Error> {
+fn parse_path(lit: syn::Lit, span: Span, field: &str) -> Result<Path, syn::Error> {
     match lit {
         syn::Lit::Str(s) => {
             let err = syn::Error::new(
                 span,
                 format!(
-                    "Failed to parse value of `{}` as ident: \"{}\"",
+                    "Failed to parse value of `{}` as path: \"{}\"",
                     field,
                     s.value()
                 ),
             );
-            let path = s.parse::<syn::Path>().map_err(|_| err.clone())?;
-            path.get_ident().cloned().ok_or(err)
+            s.parse::<syn::Path>().map_err(|_| err.clone())
         }
         _ => Err(syn::Error::new(
             span,
-            format!("Failed to parse value of `{}` as ident.", field),
+            format!("Failed to parse value of `{}` as path.", field),
         )),
     }
 }
@@ -231,7 +230,7 @@ fn parse_bool(bool: syn::Lit, span: Span, field: &str) -> Result<bool, syn::Erro
 }
 
 fn build_config(
-    input: syn::ItemFn,
+    input: &ItemFn,
     args: AttributeArgs,
     is_test: bool,
     rt_multi_thread: bool,
@@ -246,7 +245,7 @@ fn build_config(
 
     for arg in args {
         match arg {
-            syn::NestedMeta::Meta(syn::Meta::NameValue(namevalue)) => {
+            syn::Meta::NameValue(namevalue) => {
                 let ident = namevalue
                     .path
                     .get_ident()
@@ -255,34 +254,26 @@ fn build_config(
                     })?
                     .to_string()
                     .to_lowercase();
+                let lit = match &namevalue.value {
+                    syn::Expr::Lit(syn::ExprLit { lit, .. }) => lit,
+                    expr => return Err(syn::Error::new_spanned(expr, "Must be a literal")),
+                };
                 match ident.as_str() {
                     "worker_threads" => {
-                        config.set_worker_threads(
-                            namevalue.lit.clone(),
-                            syn::spanned::Spanned::span(&namevalue.lit),
-                        )?;
+                        config.set_worker_threads(lit.clone(), syn::spanned::Spanned::span(lit))?;
                     }
                     "flavor" => {
-                        config.set_flavor(
-                            namevalue.lit.clone(),
-                            syn::spanned::Spanned::span(&namevalue.lit),
-                        )?;
+                        config.set_flavor(lit.clone(), syn::spanned::Spanned::span(lit))?;
                     }
                     "start_paused" => {
-                        config.set_start_paused(
-                            namevalue.lit.clone(),
-                            syn::spanned::Spanned::span(&namevalue.lit),
-                        )?;
+                        config.set_start_paused(lit.clone(), syn::spanned::Spanned::span(lit))?;
                     }
                     "core_threads" => {
                         let msg = "Attribute `core_threads` is renamed to `worker_threads`";
                         return Err(syn::Error::new_spanned(namevalue, msg));
                     }
                     "crate" => {
-                        config.set_crate_name(
-                            namevalue.lit.clone(),
-                            syn::spanned::Spanned::span(&namevalue.lit),
-                        )?;
+                        config.set_crate_name(lit.clone(), syn::spanned::Spanned::span(lit))?;
                     }
                     name => {
                         let msg = format!(
@@ -293,7 +284,7 @@ fn build_config(
                     }
                 }
             }
-            syn::NestedMeta::Meta(syn::Meta::Path(path)) => {
+            syn::Meta::Path(path) => {
                 let name = path
                     .get_ident()
                     .ok_or_else(|| syn::Error::new_spanned(&path, "Must have specified ident"))?
@@ -333,18 +324,13 @@ fn build_config(
     config.build()
 }
 
-fn parse_knobs(mut input: syn::ItemFn, is_test: bool, config: FinalConfig) -> TokenStream {
+fn parse_knobs(mut input: 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) = {
-        let mut last_stmt = input
-            .block
-            .stmts
-            .last()
-            .map(ToTokens::into_token_stream)
-            .unwrap_or_default()
-            .into_iter();
+        let mut last_stmt = input.stmts.last().cloned().unwrap_or_default().into_iter();
+
         // `Span` on stable Rust has a limitation that only points to the first
         // token, not the whole tokens. We can work around this limitation by
         // using the first/last span of the tokens like
@@ -354,23 +340,24 @@ fn parse_knobs(mut input: syn::ItemFn, is_test: bool, config: FinalConfig) -> To
         (start, end)
     };
 
-    let crate_name = config.crate_name.as_deref().unwrap_or("tokio");
-
-    let crate_ident = Ident::new(crate_name, last_stmt_start_span);
+    let crate_path = config
+        .crate_name
+        .map(ToTokens::into_token_stream)
+        .unwrap_or_else(|| Ident::new("tokio", last_stmt_start_span).into_token_stream());
 
     let mut rt = match config.flavor {
         RuntimeFlavor::CurrentThread => quote_spanned! {last_stmt_start_span=>
-            #crate_ident::runtime::Builder::new_current_thread()
+            #crate_path::runtime::Builder::new_current_thread()
         },
         RuntimeFlavor::Threaded => quote_spanned! {last_stmt_start_span=>
-            #crate_ident::runtime::Builder::new_multi_thread()
+            #crate_path::runtime::Builder::new_multi_thread()
         },
     };
     if let Some(v) = config.worker_threads {
-        rt = quote! { #rt.worker_threads(#v) };
+        rt = quote_spanned! {last_stmt_start_span=> #rt.worker_threads(#v) };
     }
     if let Some(v) = config.start_paused {
-        rt = quote! { #rt.start_paused(#v) };
+        rt = quote_spanned! {last_stmt_start_span=> #rt.start_paused(#v) };
     }
 
     let header = if is_test {
@@ -381,10 +368,8 @@ fn parse_knobs(mut input: syn::ItemFn, is_test: bool, config: FinalConfig) -> To
         quote! {}
     };
 
-    let body = &input.block;
-    let brace_token = input.block.brace_token;
     let body_ident = quote! { body };
-    let block_expr = quote_spanned! {last_stmt_end_span=>
+    let last_block = quote_spanned! {last_stmt_end_span=>
         #[allow(clippy::expect_used, clippy::diverging_sub_expression)]
         {
             return #rt
@@ -395,6 +380,8 @@ fn parse_knobs(mut input: syn::ItemFn, is_test: bool, config: FinalConfig) -> To
         }
     };
 
+    let body = input.body();
+
     // For test functions pin the body to the stack and use `Pin<&mut dyn
     // Future>` to reduce the amount of `Runtime::block_on` (and related
     // functions) copies we generate during compilation due to the generic
@@ -414,8 +401,8 @@ fn parse_knobs(mut input: syn::ItemFn, is_test: bool, config: FinalConfig) -> To
         };
         quote! {
             let body = async #body;
-            #crate_ident::pin!(body);
-            let body: ::std::pin::Pin<&mut dyn ::std::future::Future<Output = #output_type>> = body;
+            #crate_path::pin!(body);
+            let body: ::core::pin::Pin<&mut dyn ::core::future::Future<Output = #output_type>> = body;
         }
     } else {
         quote! {
@@ -423,25 +410,11 @@ fn parse_knobs(mut input: syn::ItemFn, is_test: bool, config: FinalConfig) -> To
         }
     };
 
-    input.block = syn::parse2(quote! {
-        {
-            #body
-            #block_expr
-        }
-    })
-    .expect("Parsing failure");
-    input.block.brace_token = brace_token;
-
-    let result = quote! {
-        #header
-        #input
-    };
-
-    result.into()
+    input.into_tokens(header, body, last_block)
 }
 
 fn token_stream_with_error(mut tokens: TokenStream, error: syn::Error) -> TokenStream {
-    tokens.extend(TokenStream::from(error.into_compile_error()));
+    tokens.extend(error.into_compile_error());
     tokens
 }
 
@@ -450,7 +423,7 @@ pub(crate) fn main(args: TokenStream, item: TokenStream, rt_multi_thread: bool)
     // 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()) {
+    let input: ItemFn = match syn::parse2(item.clone()) {
         Ok(it) => it,
         Err(e) => return token_stream_with_error(item, e),
     };
@@ -460,8 +433,8 @@ pub(crate) fn main(args: TokenStream, item: TokenStream, rt_multi_thread: bool)
         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))
+            .parse2(args)
+            .and_then(|args| build_config(&input, args, false, rt_multi_thread))
     };
 
     match config {
@@ -474,17 +447,17 @@ pub(crate) fn test(args: TokenStream, item: TokenStream, rt_multi_thread: bool)
     // 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()) {
+    let input: ItemFn = match syn::parse2(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 config = if let Some(attr) = input.attrs().find(|attr| attr.meta.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))
+            .parse2(args)
+            .and_then(|args| build_config(&input, args, true, rt_multi_thread))
     };
 
     match config {
@@ -492,3 +465,127 @@ pub(crate) fn test(args: TokenStream, item: TokenStream, rt_multi_thread: bool)
         Err(e) => token_stream_with_error(parse_knobs(input, true, DEFAULT_ERROR_CONFIG), e),
     }
 }
+
+struct ItemFn {
+    outer_attrs: Vec<Attribute>,
+    vis: Visibility,
+    sig: Signature,
+    brace_token: syn::token::Brace,
+    inner_attrs: Vec<Attribute>,
+    stmts: Vec<proc_macro2::TokenStream>,
+}
+
+impl ItemFn {
+    /// Access all attributes of the function item.
+    fn attrs(&self) -> impl Iterator<Item = &Attribute> {
+        self.outer_attrs.iter().chain(self.inner_attrs.iter())
+    }
+
+    /// Get the body of the function item in a manner so that it can be
+    /// conveniently used with the `quote!` macro.
+    fn body(&self) -> Body<'_> {
+        Body {
+            brace_token: self.brace_token,
+            stmts: &self.stmts,
+        }
+    }
+
+    /// Convert our local function item into a token stream.
+    fn into_tokens(
+        self,
+        header: proc_macro2::TokenStream,
+        body: proc_macro2::TokenStream,
+        last_block: proc_macro2::TokenStream,
+    ) -> TokenStream {
+        let mut tokens = proc_macro2::TokenStream::new();
+        header.to_tokens(&mut tokens);
+
+        // Outer attributes are simply streamed as-is.
+        for attr in self.outer_attrs {
+            attr.to_tokens(&mut tokens);
+        }
+
+        // Inner attributes require extra care, since they're not supported on
+        // blocks (which is what we're expanded into) we instead lift them
+        // outside of the function. This matches the behaviour of `syn`.
+        for mut attr in self.inner_attrs {
+            attr.style = syn::AttrStyle::Outer;
+            attr.to_tokens(&mut tokens);
+        }
+
+        self.vis.to_tokens(&mut tokens);
+        self.sig.to_tokens(&mut tokens);
+
+        self.brace_token.surround(&mut tokens, |tokens| {
+            body.to_tokens(tokens);
+            last_block.to_tokens(tokens);
+        });
+
+        tokens
+    }
+}
+
+impl Parse for ItemFn {
+    #[inline]
+    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
+        // This parse implementation has been largely lifted from `syn`, with
+        // the exception of:
+        // * We don't have access to the plumbing necessary to parse inner
+        //   attributes in-place.
+        // * We do our own statements parsing to avoid recursively parsing
+        //   entire statements and only look for the parts we're interested in.
+
+        let outer_attrs = input.call(Attribute::parse_outer)?;
+        let vis: Visibility = input.parse()?;
+        let sig: Signature = input.parse()?;
+
+        let content;
+        let brace_token = braced!(content in input);
+        let inner_attrs = Attribute::parse_inner(&content)?;
+
+        let mut buf = proc_macro2::TokenStream::new();
+        let mut stmts = Vec::new();
+
+        while !content.is_empty() {
+            if let Some(semi) = content.parse::<Option<syn::Token![;]>>()? {
+                semi.to_tokens(&mut buf);
+                stmts.push(buf);
+                buf = proc_macro2::TokenStream::new();
+                continue;
+            }
+
+            // Parse a single token tree and extend our current buffer with it.
+            // This avoids parsing the entire content of the sub-tree.
+            buf.extend([content.parse::<TokenTree>()?]);
+        }
+
+        if !buf.is_empty() {
+            stmts.push(buf);
+        }
+
+        Ok(Self {
+            outer_attrs,
+            vis,
+            sig,
+            brace_token,
+            inner_attrs,
+            stmts,
+        })
+    }
+}
+
+struct Body<'a> {
+    brace_token: syn::token::Brace,
+    // Statements, with terminating `;`.
+    stmts: &'a [TokenStream],
+}
+
+impl ToTokens for Body<'_> {
+    fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
+        self.brace_token.surround(tokens, |tokens| {
+            for stmt in self.stmts {
+                stmt.to_tokens(tokens);
+            }
+        });
+    }
+}

tokio-macros/src/lib.rs

@@ -39,6 +39,13 @@ use proc_macro::TokenStream;
 /// function is called often, it is preferable to create the runtime using the
 /// runtime builder so the runtime can be reused across calls.
 ///
+/// # Non-worker async function
+///
+/// Note that the async function marked with this macro does not run as a
+/// worker. The expectation is that other tasks are spawned by the function here.
+/// Awaiting on other futures from the function provided here will not
+/// perform as fast as those spawned as workers.
+///
 /// # Multi-threaded runtime
 ///
 /// To use the multi-threaded runtime, the macro can be configured using
@@ -197,12 +204,12 @@ use proc_macro::TokenStream;
 #[proc_macro_attribute]
 #[cfg(not(test))] // Work around for rust-lang/rust#62127
 pub fn main(args: TokenStream, item: TokenStream) -> TokenStream {
-    entry::main(args, item, true)
+    entry::main(args.into(), item.into(), true).into()
 }
 
 /// Marks async function to be executed by selected runtime. This macro helps set up a `Runtime`
 /// without requiring the user to use [Runtime](../tokio/runtime/struct.Runtime.html) or
-/// [Builder](../tokio/runtime/struct.builder.html) directly.
+/// [Builder](../tokio/runtime/struct.Builder.html) directly.
 ///
 /// ## Function arguments:
 ///
@@ -262,7 +269,7 @@ pub fn main(args: TokenStream, item: TokenStream) -> TokenStream {
 #[proc_macro_attribute]
 #[cfg(not(test))] // Work around for rust-lang/rust#62127
 pub fn main_rt(args: TokenStream, item: TokenStream) -> TokenStream {
-    entry::main(args, item, false)
+    entry::main(args.into(), item.into(), false).into()
 }
 
 /// Marks async function to be executed by runtime, suitable to test environment.
@@ -288,8 +295,7 @@ pub fn main_rt(args: TokenStream, item: TokenStream) -> TokenStream {
 /// ```
 ///
 /// The `worker_threads` option configures the number of worker threads, and
-/// defaults to the number of cpus on the system. This is the default
-/// flavor.
+/// defaults to the number of cpus on the system.
 ///
 /// Note: The multi-threaded runtime requires the `rt-multi-thread` feature
 /// flag.
@@ -420,7 +426,7 @@ pub fn main_rt(args: TokenStream, item: TokenStream) -> TokenStream {
 /// ```
 #[proc_macro_attribute]
 pub fn test(args: TokenStream, item: TokenStream) -> TokenStream {
-    entry::test(args, item, true)
+    entry::test(args.into(), item.into(), true).into()
 }
 
 /// Marks async function to be executed by runtime, suitable to test environment
@@ -435,7 +441,7 @@ pub fn test(args: TokenStream, item: TokenStream) -> TokenStream {
 /// ```
 #[proc_macro_attribute]
 pub fn test_rt(args: TokenStream, item: TokenStream) -> TokenStream {
-    entry::test(args, item, false)
+    entry::test(args.into(), item.into(), false).into()
 }
 
 /// Always fails with the error message below.

tokio-macros/src/select.rs

@@ -1,7 +1,7 @@
 use proc_macro::{TokenStream, TokenTree};
 use proc_macro2::Span;
 use quote::quote;
-use syn::Ident;
+use syn::{parse::Parser, Ident};
 
 pub(crate) fn declare_output_enum(input: TokenStream) -> TokenStream {
     // passed in is: `(_ _ _)` with one `_` per branch
@@ -46,7 +46,7 @@ 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()) {
+    let mut input: syn::Pat = match syn::Pat::parse_single.parse(input.clone()) {
         Ok(it) => it,
         Err(_) => return input,
     };
@@ -58,7 +58,6 @@ pub(crate) fn clean_pattern_macro(input: TokenStream) -> TokenStream {
 // 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) => {}
@@ -74,36 +73,36 @@ fn clean_pattern(pat: &mut syn::Pat) {
             }
         }
         syn::Pat::Or(or) => {
-            for case in or.cases.iter_mut() {
+            for case in &mut or.cases {
                 clean_pattern(case);
             }
         }
         syn::Pat::Slice(slice) => {
-            for elem in slice.elems.iter_mut() {
+            for elem in &mut slice.elems {
                 clean_pattern(elem);
             }
         }
         syn::Pat::Struct(struct_pat) => {
-            for field in struct_pat.fields.iter_mut() {
+            for field in &mut struct_pat.fields {
                 clean_pattern(&mut field.pat);
             }
         }
         syn::Pat::Tuple(tuple) => {
-            for elem in tuple.elems.iter_mut() {
+            for elem in &mut tuple.elems {
                 clean_pattern(elem);
             }
         }
         syn::Pat::TupleStruct(tuple) => {
-            for elem in tuple.pat.elems.iter_mut() {
+            for elem in &mut tuple.elems {
                 clean_pattern(elem);
             }
         }
         syn::Pat::Reference(reference) => {
             reference.mutability = None;
-            clean_pattern(&mut *reference.pat);
+            clean_pattern(&mut reference.pat);
         }
         syn::Pat::Type(type_pat) => {
-            clean_pattern(&mut *type_pat.pat);
+            clean_pattern(&mut type_pat.pat);
         }
         _ => {}
     }

tokio-stream/CHANGELOG.md

@@ -1,3 +1,32 @@
+# 0.1.14 (April 26th, 2023)
+
+This bugfix release bumps the minimum version of Tokio to 1.15, which is
+necessary for `timeout_repeating` to compile. ([#5657])
+
+[#5657]: https://github.com/tokio-rs/tokio/pull/5657
+
+# 0.1.13 (April 25th, 2023)
+
+This release bumps the MSRV of tokio-stream to 1.56.
+
+- stream: add "full" feature flag ([#5639])
+- stream: add `StreamExt::timeout_repeating` ([#5577])
+- stream: add `StreamNotifyClose` ([#4851])
+
+[#4851]: https://github.com/tokio-rs/tokio/pull/4851
+[#5577]: https://github.com/tokio-rs/tokio/pull/5577
+[#5639]: https://github.com/tokio-rs/tokio/pull/5639
+
+# 0.1.12 (January 20, 2023)
+
+- time: remove `Unpin` bound on `Throttle` methods ([#5105])
+- time: document that `throttle` operates on ms granularity ([#5101])
+- sync: add `WatchStream::from_changes` ([#5432])
+
+[#5105]: https://github.com/tokio-rs/tokio/pull/5105
+[#5101]: https://github.com/tokio-rs/tokio/pull/5101
+[#5432]: https://github.com/tokio-rs/tokio/pull/5432
+
 # 0.1.11 (October 11, 2022)
 
 - time: allow `StreamExt::chunks_timeout` outside of a runtime ([#5036])

tokio-stream/Cargo.toml

@@ -4,9 +4,9 @@ name = "tokio-stream"
 # - Remove path dependencies
 # - Update CHANGELOG.md.
 # - Create "tokio-stream-0.1.x" git tag.
-version = "0.1.11"
-edition = "2018"
-rust-version = "1.49"
+version = "0.1.14"
+edition = "2021"
+rust-version = "1.63"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
@@ -18,6 +18,16 @@ categories = ["asynchronous"]
 
 [features]
 default = ["time"]
+
+full = [
+    "time",
+    "net",
+    "io-util",
+    "fs",
+    "sync",
+    "signal"
+]
+
 time = ["tokio/time"]
 net = ["tokio/net"]
 io-util = ["tokio/io-util"]
@@ -27,8 +37,8 @@ signal = ["tokio/signal"]
 
 [dependencies]
 futures-core = { version = "0.3.0" }
-pin-project-lite = "0.2.0"
-tokio = { version = "1.8.0", path = "../tokio", features = ["sync"] }
+pin-project-lite = "0.2.11"
+tokio = { version = "1.15.0", path = "../tokio", features = ["sync"] }
 tokio-util = { version = "0.7.0", path = "../tokio-util", optional = true }
 
 [dev-dependencies]
@@ -38,9 +48,6 @@ parking_lot = "0.12.0"
 tokio-test = { path = "../tokio-test" }
 futures = { version = "0.3", default-features = false }
 
-[target.'cfg(not(target_arch = "wasm32"))'.dev-dependencies]
-proptest = "1"
-
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]

tokio-stream/LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2022 Tokio Contributors
+Copyright (c) 2023 Tokio Contributors
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated

tokio-stream/fuzz/.gitignore

@@ -0,0 +1,4 @@
+target
+corpus
+artifacts
+coverage

tokio-stream/fuzz/Cargo.toml

@@ -0,0 +1,29 @@
+[package]
+name = "tokio-stream-fuzz"
+version = "0.0.0"
+publish = false
+edition = "2021"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.4"
+tokio-test = { path = "../../tokio-test" }
+
+[dependencies.tokio-stream]
+path = ".."
+
+
+# Prevent this from interfering with workspaces
+[workspace]
+members = ["."]
+
+[profile.release]
+debug = 1
+
+[[bin]]
+name = "fuzz_stream_map"
+path = "fuzz_targets/fuzz_stream_map.rs"
+test = false
+doc = false

tokio-stream/fuzz/fuzz_targets/fuzz_stream_map.rs

@@ -0,0 +1,72 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+use std::pin::Pin;
+
+use tokio_stream::{self as stream, Stream, StreamMap};
+use tokio_test::{assert_pending, assert_ready, task};
+
+macro_rules! assert_ready_none {
+    ($($t:tt)*) => {
+        match assert_ready!($($t)*) {
+            None => {}
+            Some(v) => panic!("expected `None`, got `Some({:?})`", v),
+        }
+    };
+}
+
+fn pin_box<T: Stream<Item = U> + 'static, U>(s: T) -> Pin<Box<dyn Stream<Item = U>>> {
+    Box::pin(s)
+}
+
+fuzz_target!(|data: [bool; 64]| {
+    use std::task::{Context, Poll};
+
+    struct DidPoll<T> {
+        did_poll: bool,
+        inner: T,
+    }
+
+    impl<T: Stream + Unpin> Stream for DidPoll<T> {
+        type Item = T::Item;
+
+        fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T::Item>> {
+            self.did_poll = true;
+            Pin::new(&mut self.inner).poll_next(cx)
+        }
+    }
+
+    // Try the test with each possible length.
+    for len in 0..data.len() {
+        let mut map = task::spawn(StreamMap::new());
+        let mut expect = 0;
+
+        for (i, is_empty) in data[..len].iter().copied().enumerate() {
+            let inner = if is_empty {
+                pin_box(stream::empty::<()>())
+            } else {
+                expect += 1;
+                pin_box(stream::pending::<()>())
+            };
+
+            let stream = DidPoll {
+                did_poll: false,
+                inner,
+            };
+
+            map.insert(i, stream);
+        }
+
+        if expect == 0 {
+            assert_ready_none!(map.poll_next());
+        } else {
+            assert_pending!(map.poll_next());
+
+            assert_eq!(expect, map.values().count());
+
+            for stream in map.values() {
+                assert!(stream.did_poll);
+            }
+        }
+    }
+});

tokio-stream/src/lib.rs

@@ -63,12 +63,12 @@
 //! [`tokio-util`] provides the [`StreamReader`] and [`ReaderStream`]
 //! types when the io feature is enabled.
 //!
-//! [`tokio-util`]: https://docs.rs/tokio-util/0.4/tokio_util/codec/index.html
-//! [`tokio::io`]: https://docs.rs/tokio/1.0/tokio/io/index.html
-//! [`AsyncRead`]: https://docs.rs/tokio/1.0/tokio/io/trait.AsyncRead.html
-//! [`AsyncWrite`]: https://docs.rs/tokio/1.0/tokio/io/trait.AsyncWrite.html
-//! [`ReaderStream`]: https://docs.rs/tokio-util/0.4/tokio_util/io/struct.ReaderStream.html
-//! [`StreamReader`]: https://docs.rs/tokio-util/0.4/tokio_util/io/struct.StreamReader.html
+//! [`tokio-util`]: https://docs.rs/tokio-util/latest/tokio_util/codec/index.html
+//! [`tokio::io`]: https://docs.rs/tokio/latest/tokio/io/index.html
+//! [`AsyncRead`]: https://docs.rs/tokio/latest/tokio/io/trait.AsyncRead.html
+//! [`AsyncWrite`]: https://docs.rs/tokio/latest/tokio/io/trait.AsyncWrite.html
+//! [`ReaderStream`]: https://docs.rs/tokio-util/latest/tokio_util/io/struct.ReaderStream.html
+//! [`StreamReader`]: https://docs.rs/tokio-util/latest/tokio_util/io/struct.StreamReader.html
 
 #[macro_use]
 mod macros;
@@ -96,5 +96,8 @@ pub use pending::{pending, Pending};
 mod stream_map;
 pub use stream_map::StreamMap;
 
+mod stream_close;
+pub use stream_close::StreamNotifyClose;
+
 #[doc(no_inline)]
 pub use futures_core::Stream;

tokio-stream/src/once.rs

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

tokio-stream/src/stream_close.rs

@@ -0,0 +1,93 @@
+use crate::Stream;
+use pin_project_lite::pin_project;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+pin_project! {
+    /// A `Stream` that wraps the values in an `Option`.
+    ///
+    /// Whenever the wrapped stream yields an item, this stream yields that item
+    /// wrapped in `Some`. When the inner stream ends, then this stream first
+    /// yields a `None` item, and then this stream will also end.
+    ///
+    /// # Example
+    ///
+    /// Using `StreamNotifyClose` to handle closed streams with `StreamMap`.
+    ///
+    /// ```
+    /// use tokio_stream::{StreamExt, StreamMap, StreamNotifyClose};
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let mut map = StreamMap::new();
+    ///     let stream = StreamNotifyClose::new(tokio_stream::iter(vec![0, 1]));
+    ///     let stream2 = StreamNotifyClose::new(tokio_stream::iter(vec![0, 1]));
+    ///     map.insert(0, stream);
+    ///     map.insert(1, stream2);
+    ///     while let Some((key, val)) = map.next().await {
+    ///         match val {
+    ///             Some(val) => println!("got {val:?} from stream {key:?}"),
+    ///             None => println!("stream {key:?} closed"),
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    #[must_use = "streams do nothing unless polled"]
+    pub struct StreamNotifyClose<S> {
+        #[pin]
+        inner: Option<S>,
+    }
+}
+
+impl<S> StreamNotifyClose<S> {
+    /// Create a new `StreamNotifyClose`.
+    pub fn new(stream: S) -> Self {
+        Self {
+            inner: Some(stream),
+        }
+    }
+
+    /// Get back the inner `Stream`.
+    ///
+    /// Returns `None` if the stream has reached its end.
+    pub fn into_inner(self) -> Option<S> {
+        self.inner
+    }
+}
+
+impl<S> Stream for StreamNotifyClose<S>
+where
+    S: Stream,
+{
+    type Item = Option<S::Item>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        // We can't invoke poll_next after it ended, so we unset the inner stream as a marker.
+        match self
+            .as_mut()
+            .project()
+            .inner
+            .as_pin_mut()
+            .map(|stream| S::poll_next(stream, cx))
+        {
+            Some(Poll::Ready(Some(item))) => Poll::Ready(Some(Some(item))),
+            Some(Poll::Ready(None)) => {
+                self.project().inner.set(None);
+                Poll::Ready(Some(None))
+            }
+            Some(Poll::Pending) => Poll::Pending,
+            None => Poll::Ready(None),
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        if let Some(inner) = &self.inner {
+            // We always return +1 because when there's stream there's atleast one more item.
+            let (l, u) = inner.size_hint();
+            (l.saturating_add(1), u.and_then(|u| u.checked_add(1)))
+        } else {
+            (0, Some(0))
+        }
+    }
+}

tokio-stream/src/stream_ext.rs

@@ -55,10 +55,15 @@ use then::Then;
 mod try_next;
 use try_next::TryNext;
 
+mod peekable;
+use peekable::Peekable;
+
 cfg_time! {
     pub(crate) mod timeout;
+    pub(crate) mod timeout_repeating;
     use timeout::Timeout;
-    use tokio::time::Duration;
+    use timeout_repeating::TimeoutRepeating;
+    use tokio::time::{Duration, Interval};
     mod throttle;
     use throttle::{throttle, Throttle};
     mod chunks_timeout;
@@ -846,8 +851,7 @@ pub trait StreamExt: Stream {
     ///
     /// `collect` streams all values, awaiting as needed. Values are pushed into
     /// a collection. A number of different target collection types are
-    /// supported, including [`Vec`](std::vec::Vec),
-    /// [`String`](std::string::String), and [`Bytes`].
+    /// supported, including [`Vec`], [`String`], and [`Bytes`].
     ///
     /// [`Bytes`]: https://docs.rs/bytes/0.6.0/bytes/struct.Bytes.html
     ///
@@ -924,7 +928,9 @@ pub trait StreamExt: Stream {
     /// If the wrapped stream yields a value before the deadline is reached, the
     /// value is returned. Otherwise, an error is returned. The caller may decide
     /// to continue consuming the stream and will eventually get the next source
-    /// stream value once it becomes available.
+    /// stream value once it becomes available. See
+    /// [`timeout_repeating`](StreamExt::timeout_repeating) for an alternative
+    /// where the timeouts will repeat.
     ///
     /// # Notes
     ///
@@ -971,7 +977,26 @@ pub trait StreamExt: Stream {
     /// assert_eq!(int_stream.try_next().await, Ok(None));
     /// # }
     /// ```
-    #[cfg(all(feature = "time"))]
+    ///
+    /// Once a timeout error is received, no further events will be received
+    /// unless the wrapped stream yields a value (timeouts do not repeat).
+    ///
+    /// ```
+    /// # #[tokio::main(flavor = "current_thread", start_paused = true)]
+    /// # async fn main() {
+    /// use tokio_stream::{StreamExt, wrappers::IntervalStream};
+    /// use std::time::Duration;
+    /// let interval_stream = IntervalStream::new(tokio::time::interval(Duration::from_millis(100)));
+    /// let timeout_stream = interval_stream.timeout(Duration::from_millis(10));
+    /// tokio::pin!(timeout_stream);
+    ///
+    /// // Only one timeout will be received between values in the source stream.
+    /// assert!(timeout_stream.try_next().await.is_ok());
+    /// assert!(timeout_stream.try_next().await.is_err(), "expected one timeout");
+    /// assert!(timeout_stream.try_next().await.is_ok(), "expected no more timeouts");
+    /// # }
+    /// ```
+    #[cfg(feature = "time")]
     #[cfg_attr(docsrs, doc(cfg(feature = "time")))]
     fn timeout(self, duration: Duration) -> Timeout<Self>
     where
@@ -980,6 +1005,94 @@ pub trait StreamExt: Stream {
         Timeout::new(self, duration)
     }
 
+    /// Applies a per-item timeout to the passed stream.
+    ///
+    /// `timeout_repeating()` takes an [`Interval`] that controls the time each
+    /// element of the stream has to complete before timing out.
+    ///
+    /// If the wrapped stream yields a value before the deadline is reached, the
+    /// value is returned. Otherwise, an error is returned. The caller may decide
+    /// to continue consuming the stream and will eventually get the next source
+    /// stream value once it becomes available. Unlike `timeout()`, if no value
+    /// becomes available before the deadline is reached, additional errors are
+    /// returned at the specified interval. See [`timeout`](StreamExt::timeout)
+    /// for an alternative where the timeouts do not repeat.
+    ///
+    /// # Notes
+    ///
+    /// This function consumes the stream passed into it and returns a
+    /// wrapped version of it.
+    ///
+    /// Polling the returned stream will continue to poll the inner stream even
+    /// if one or more items time out.
+    ///
+    /// # Examples
+    ///
+    /// Suppose we have a stream `int_stream` that yields 3 numbers (1, 2, 3):
+    ///
+    /// ```
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// use tokio_stream::{self as stream, StreamExt};
+    /// use std::time::Duration;
+    /// # let int_stream = stream::iter(1..=3);
+    ///
+    /// let int_stream = int_stream.timeout_repeating(tokio::time::interval(Duration::from_secs(1)));
+    /// tokio::pin!(int_stream);
+    ///
+    /// // When no items time out, we get the 3 elements in succession:
+    /// assert_eq!(int_stream.try_next().await, Ok(Some(1)));
+    /// assert_eq!(int_stream.try_next().await, Ok(Some(2)));
+    /// assert_eq!(int_stream.try_next().await, Ok(Some(3)));
+    /// assert_eq!(int_stream.try_next().await, Ok(None));
+    ///
+    /// // If the second item times out, we get an error and continue polling the stream:
+    /// # let mut int_stream = stream::iter(vec![Ok(1), Err(()), Ok(2), Ok(3)]);
+    /// assert_eq!(int_stream.try_next().await, Ok(Some(1)));
+    /// assert!(int_stream.try_next().await.is_err());
+    /// assert_eq!(int_stream.try_next().await, Ok(Some(2)));
+    /// assert_eq!(int_stream.try_next().await, Ok(Some(3)));
+    /// assert_eq!(int_stream.try_next().await, Ok(None));
+    ///
+    /// // If we want to stop consuming the source stream the first time an
+    /// // element times out, we can use the `take_while` operator:
+    /// # let int_stream = stream::iter(vec![Ok(1), Err(()), Ok(2), Ok(3)]);
+    /// let mut int_stream = int_stream.take_while(Result::is_ok);
+    ///
+    /// assert_eq!(int_stream.try_next().await, Ok(Some(1)));
+    /// assert_eq!(int_stream.try_next().await, Ok(None));
+    /// # }
+    /// ```
+    ///
+    /// Timeout errors will be continuously produced at the specified interval
+    /// until the wrapped stream yields a value.
+    ///
+    /// ```
+    /// # #[tokio::main(flavor = "current_thread", start_paused = true)]
+    /// # async fn main() {
+    /// use tokio_stream::{StreamExt, wrappers::IntervalStream};
+    /// use std::time::Duration;
+    /// let interval_stream = IntervalStream::new(tokio::time::interval(Duration::from_millis(23)));
+    /// let timeout_stream = interval_stream.timeout_repeating(tokio::time::interval(Duration::from_millis(9)));
+    /// tokio::pin!(timeout_stream);
+    ///
+    /// // Multiple timeouts will be received between values in the source stream.
+    /// assert!(timeout_stream.try_next().await.is_ok());
+    /// assert!(timeout_stream.try_next().await.is_err(), "expected one timeout");
+    /// assert!(timeout_stream.try_next().await.is_err(), "expected a second timeout");
+    /// // Will eventually receive another value from the source stream...
+    /// assert!(timeout_stream.try_next().await.is_ok(), "expected non-timeout");
+    /// # }
+    /// ```
+    #[cfg(feature = "time")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "time")))]
+    fn timeout_repeating(self, interval: Interval) -> TimeoutRepeating<Self>
+    where
+        Self: Sized,
+    {
+        TimeoutRepeating::new(self, interval)
+    }
+
     /// Slows down a stream by enforcing a delay between items.
     ///
     /// The underlying timer behind this utility has a granularity of one millisecond.
@@ -1001,7 +1114,7 @@ pub trait StreamExt: Stream {
     /// }
     /// # }
     /// ```
-    #[cfg(all(feature = "time"))]
+    #[cfg(feature = "time")]
     #[cfg_attr(docsrs, doc(cfg(feature = "time")))]
     fn throttle(self, duration: Duration) -> Throttle<Self>
     where
@@ -1066,6 +1179,31 @@ pub trait StreamExt: Stream {
         assert!(max_size > 0, "`max_size` must be non-zero.");
         ChunksTimeout::new(self, max_size, duration)
     }
+
+    /// Turns the stream into a peekable stream, whose next element can be peeked at without being
+    /// consumed.
+    /// ```rust
+    /// use tokio_stream::{self as stream, StreamExt};
+    ///
+    /// #[tokio::main]
+    /// # async fn _unused() {}
+    /// # #[tokio::main(flavor = "current_thread", start_paused = true)]
+    /// async fn main() {
+    ///     let iter = vec![1, 2, 3, 4].into_iter();
+    ///     let mut stream = stream::iter(iter).peekable();
+    ///
+    ///     assert_eq!(*stream.peek().await.unwrap(), 1);
+    ///     assert_eq!(*stream.peek().await.unwrap(), 1);
+    ///     assert_eq!(stream.next().await.unwrap(), 1);
+    ///     assert_eq!(*stream.peek().await.unwrap(), 2);
+    /// }
+    /// ```
+    fn peekable(self) -> Peekable<Self>
+    where
+        Self: Sized,
+    {
+        Peekable::new(self)
+    }
 }
 
 impl<St: ?Sized> StreamExt for St where St: Stream {}

tokio-stream/src/stream_ext/collect.rs

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

tokio-stream/src/stream_ext/merge.rs

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

tokio-stream/src/stream_ext/peekable.rs

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

tokio-stream/src/stream_ext/take.rs

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

tokio-stream/src/stream_ext/then.rs

@@ -72,7 +72,7 @@ where
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        let future_len = if self.future.is_some() { 1 } else { 0 };
+        let future_len = usize::from(self.future.is_some());
         let (lower, upper) = self.stream.size_hint();
 
         let lower = lower.saturating_add(future_len);

tokio-stream/src/stream_ext/timeout.rs

@@ -23,7 +23,7 @@ pin_project! {
     }
 }
 
-/// Error returned by `Timeout`.
+/// Error returned by `Timeout` and `TimeoutRepeating`.
 #[derive(Debug, PartialEq, Eq)]
 pub struct Elapsed(());
 

tokio-stream/src/stream_ext/timeout_repeating.rs

@@ -0,0 +1,56 @@
+use crate::stream_ext::Fuse;
+use crate::{Elapsed, Stream};
+use tokio::time::Interval;
+
+use core::pin::Pin;
+use core::task::{Context, Poll};
+use pin_project_lite::pin_project;
+
+pin_project! {
+    /// Stream returned by the [`timeout_repeating`](super::StreamExt::timeout_repeating) method.
+    #[must_use = "streams do nothing unless polled"]
+    #[derive(Debug)]
+    pub struct TimeoutRepeating<S> {
+        #[pin]
+        stream: Fuse<S>,
+        #[pin]
+        interval: Interval,
+    }
+}
+
+impl<S: Stream> TimeoutRepeating<S> {
+    pub(super) fn new(stream: S, interval: Interval) -> Self {
+        TimeoutRepeating {
+            stream: Fuse::new(stream),
+            interval,
+        }
+    }
+}
+
+impl<S: Stream> Stream for TimeoutRepeating<S> {
+    type Item = Result<S::Item, Elapsed>;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        let mut me = self.project();
+
+        match me.stream.poll_next(cx) {
+            Poll::Ready(v) => {
+                if v.is_some() {
+                    me.interval.reset();
+                }
+                return Poll::Ready(v.map(Ok));
+            }
+            Poll::Pending => {}
+        };
+
+        ready!(me.interval.poll_tick(cx));
+        Poll::Ready(Some(Err(Elapsed::new())))
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let (lower, _) = self.stream.size_hint();
+
+        // The timeout stream may insert an error an infinite number of times.
+        (lower, None)
+    }
+}

tokio-stream/src/stream_map.rs

@@ -42,10 +42,18 @@ use std::task::{Context, Poll};
 /// to be merged, it may be advisable to use tasks sending values on a shared
 /// [`mpsc`] channel.
 ///
+/// # Notes
+///
+/// `StreamMap` removes finished streams automatically, without alerting the user.
+/// In some scenarios, the caller would want to know on closed streams.
+/// To do this, use [`StreamNotifyClose`] as a wrapper to your stream.
+/// It will return None when the stream is closed.
+///
 /// [`StreamExt::merge`]: crate::StreamExt::merge
 /// [`mpsc`]: https://docs.rs/tokio/1.0/tokio/sync/mpsc/index.html
 /// [`pin!`]: https://docs.rs/tokio/1.0/tokio/macro.pin.html
 /// [`Box::pin`]: std::boxed::Box::pin
+/// [`StreamNotifyClose`]: crate::StreamNotifyClose
 ///
 /// # Examples
 ///
@@ -170,6 +178,28 @@ use std::task::{Context, Poll};
 ///     }
 /// }
 /// ```
+///
+/// Using `StreamNotifyClose` to handle closed streams with `StreamMap`.
+///
+/// ```
+/// use tokio_stream::{StreamExt, StreamMap, StreamNotifyClose};
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let mut map = StreamMap::new();
+///     let stream = StreamNotifyClose::new(tokio_stream::iter(vec![0, 1]));
+///     let stream2 = StreamNotifyClose::new(tokio_stream::iter(vec![0, 1]));
+///     map.insert(0, stream);
+///     map.insert(1, stream2);
+///     while let Some((key, val)) = map.next().await {
+///         match val {
+///             Some(val) => println!("got {val:?} from stream {key:?}"),
+///             None => println!("stream {key:?} closed"),
+///         }
+///     }
+/// }
+/// ```
+
 #[derive(Debug)]
 pub struct StreamMap<K, V> {
     /// Streams stored in the map
@@ -488,8 +518,6 @@ where
 {
     /// Polls the next value, includes the vec entry index
     fn poll_next_entry(&mut self, cx: &mut Context<'_>) -> Poll<Option<(usize, V::Item)>> {
-        use Poll::*;
-
         let start = self::rand::thread_rng_n(self.entries.len() as u32) as usize;
         let mut idx = start;
 
@@ -497,8 +525,8 @@ where
             let (_, stream) = &mut self.entries[idx];
 
             match Pin::new(stream).poll_next(cx) {
-                Ready(Some(val)) => return Ready(Some((idx, val))),
-                Ready(None) => {
+                Poll::Ready(Some(val)) => return Poll::Ready(Some((idx, val))),
+                Poll::Ready(None) => {
                     // Remove the entry
                     self.entries.swap_remove(idx);
 
@@ -512,7 +540,7 @@ where
                         idx = idx.wrapping_add(1) % self.entries.len();
                     }
                 }
-                Pending => {
+                Poll::Pending => {
                     idx = idx.wrapping_add(1) % self.entries.len();
                 }
             }
@@ -520,9 +548,9 @@ where
 
         // If the map is empty, then the stream is complete.
         if self.entries.is_empty() {
-            Ready(None)
+            Poll::Ready(None)
         } else {
-            Pending
+            Poll::Pending
         }
     }
 }
@@ -568,7 +596,7 @@ where
     }
 }
 
-impl<K, V> std::iter::FromIterator<(K, V)> for StreamMap<K, V>
+impl<K, V> FromIterator<(K, V)> for StreamMap<K, V>
 where
     K: Hash + Eq,
 {

tokio-stream/src/wrappers/mpsc_bounded.rs

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

tokio-stream/src/wrappers/mpsc_unbounded.rs

@@ -28,7 +28,7 @@ impl<T> UnboundedReceiverStream<T> {
     /// This prevents any further messages from being sent on the channel while
     /// still enabling the receiver to drain messages that are buffered.
     pub fn close(&mut self) {
-        self.inner.close()
+        self.inner.close();
     }
 }
 

tokio-stream/src/wrappers/watch.rs

@@ -10,8 +10,9 @@ 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,
-/// regardless of whether it was the initial value or sent afterwards.
+/// This stream will start by yielding the current value when the WatchStream is polled,
+/// regardless of whether it was the initial value or sent afterwards,
+/// unless you use [`WatchStream<T>::from_changes`].
 ///
 /// # Examples
 ///
@@ -40,6 +41,28 @@ use tokio::sync::watch::error::RecvError;
 /// let (tx, rx) = watch::channel("hello");
 /// let mut rx = WatchStream::new(rx);
 ///
+/// // existing rx output with "hello" is ignored here
+///
+/// tx.send("goodbye").unwrap();
+/// assert_eq!(rx.next().await, Some("goodbye"));
+/// # }
+/// ```
+///
+/// Example with [`WatchStream<T>::from_changes`]:
+///
+/// ```
+/// # #[tokio::main]
+/// # async fn main() {
+/// use futures::future::FutureExt;
+/// use tokio::sync::watch;
+/// use tokio_stream::{StreamExt, wrappers::WatchStream};
+///
+/// let (tx, rx) = watch::channel("hello");
+/// let mut rx = WatchStream::from_changes(rx);
+///
+/// // no output from rx is available at this point - let's check this:
+/// assert!(rx.next().now_or_never().is_none());
+///
 /// tx.send("goodbye").unwrap();
 /// assert_eq!(rx.next().await, Some("goodbye"));
 /// # }
@@ -66,6 +89,13 @@ impl<T: 'static + Clone + Send + Sync> WatchStream<T> {
             inner: ReusableBoxFuture::new(async move { (Ok(()), rx) }),
         }
     }
+
+    /// Create a new `WatchStream` that waits for the value to be changed.
+    pub fn from_changes(rx: Receiver<T>) -> Self {
+        Self {
+            inner: ReusableBoxFuture::new(make_future(rx)),
+        }
+    }
 }
 
 impl<T: Clone + 'static + Send + Sync> Stream for WatchStream<T> {

tokio-stream/tests/stream_close.rs

@@ -0,0 +1,11 @@
+use tokio_stream::{StreamExt, StreamNotifyClose};
+
+#[tokio::test]
+async fn basic_usage() {
+    let mut stream = StreamNotifyClose::new(tokio_stream::iter(vec![0, 1]));
+
+    assert_eq!(stream.next().await, Some(Some(0)));
+    assert_eq!(stream.next().await, Some(Some(1)));
+    assert_eq!(stream.next().await, Some(None));
+    assert_eq!(stream.next().await, None);
+}

tokio-stream/tests/stream_stream_map.rs

@@ -325,63 +325,6 @@ fn one_ready_many_none() {
     }
 }
 
-#[cfg(not(target_os = "wasi"))]
-proptest::proptest! {
-    #[test]
-    fn fuzz_pending_complete_mix(kinds: Vec<bool>) {
-        use std::task::{Context, Poll};
-
-        struct DidPoll<T> {
-            did_poll: bool,
-            inner: T,
-        }
-
-        impl<T: Stream + Unpin> Stream for DidPoll<T> {
-            type Item = T::Item;
-
-            fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>)
-                -> Poll<Option<T::Item>>
-            {
-                self.did_poll = true;
-                Pin::new(&mut self.inner).poll_next(cx)
-            }
-        }
-
-        for _ in 0..10 {
-            let mut map = task::spawn(StreamMap::new());
-            let mut expect = 0;
-
-            for (i, &is_empty) in kinds.iter().enumerate() {
-                let inner = if is_empty {
-                    pin_box(stream::empty::<()>())
-                } else {
-                    expect += 1;
-                    pin_box(stream::pending::<()>())
-                };
-
-                let stream = DidPoll {
-                    did_poll: false,
-                    inner,
-                };
-
-                map.insert(i, stream);
-            }
-
-            if expect == 0 {
-                assert_ready_none!(map.poll_next());
-            } else {
-                assert_pending!(map.poll_next());
-
-                assert_eq!(expect, map.values().count());
-
-                for stream in map.values() {
-                    assert!(stream.did_poll);
-                }
-            }
-        }
-    }
-}
-
 fn pin_box<T: Stream<Item = U> + 'static, U>(s: T) -> Pin<Box<dyn Stream<Item = U>>> {
     Box::pin(s)
 }

tokio-stream/tests/watch.rs

@@ -3,9 +3,11 @@
 use tokio::sync::watch;
 use tokio_stream::wrappers::WatchStream;
 use tokio_stream::StreamExt;
+use tokio_test::assert_pending;
+use tokio_test::task::spawn;
 
 #[tokio::test]
-async fn message_not_twice() {
+async fn watch_stream_message_not_twice() {
     let (tx, rx) = watch::channel("hello");
 
     let mut counter = 0;
@@ -27,3 +29,29 @@ async fn message_not_twice() {
     drop(tx);
     task.await.unwrap();
 }
+
+#[tokio::test]
+async fn watch_stream_from_rx() {
+    let (tx, rx) = watch::channel("hello");
+
+    let mut stream = WatchStream::from(rx);
+
+    assert_eq!(stream.next().await.unwrap(), "hello");
+
+    tx.send("bye").unwrap();
+
+    assert_eq!(stream.next().await.unwrap(), "bye");
+}
+
+#[tokio::test]
+async fn watch_stream_from_changes() {
+    let (tx, rx) = watch::channel("hello");
+
+    let mut stream = WatchStream::from_changes(rx);
+
+    assert_pending!(spawn(&mut stream).poll_next());
+
+    tx.send("bye").unwrap();
+
+    assert_eq!(stream.next().await.unwrap(), "bye");
+}

tokio-test/CHANGELOG.md

@@ -1,3 +1,17 @@
+# 0.4.3 (August 23, 2023)
+
+- deps: fix minimum required version of `async-stream` ([#5347])
+- deps: fix minimum required version of `tokio-stream` ([#4376])
+- docs: improve `tokio_test::task` docs ([#5132])
+- io: fetch actions from mock handle before write ([#5814])
+- io: fix wait operation on mock ([#5554])
+
+[#4376]: https://github.com/tokio-rs/tokio/pull/4376
+[#5132]: https://github.com/tokio-rs/tokio/pull/5132
+[#5347]: https://github.com/tokio-rs/tokio/pull/5347
+[#5554]: https://github.com/tokio-rs/tokio/pull/5554
+[#5814]: https://github.com/tokio-rs/tokio/pull/5814
+
 # 0.4.2 (May 14, 2021)
 
 - test: add `assert_elapsed!` macro ([#3728])

tokio-test/Cargo.toml

@@ -4,9 +4,9 @@ name = "tokio-test"
 # - Remove path dependencies
 # - Update CHANGELOG.md.
 # - Create "tokio-test-0.4.x" git tag.
-version = "0.4.2"
-edition = "2018"
-rust-version = "1.49"
+version = "0.4.3"
+edition = "2021"
+rust-version = "1.63"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
@@ -14,12 +14,12 @@ homepage = "https://tokio.rs"
 description = """
 Testing utilities for Tokio- and futures-based code
 """
-categories = ["asynchronous", "testing"]
+categories = ["asynchronous", "development-tools::testing"]
 
 [dependencies]
 tokio = { version = "1.2.0", path = "../tokio", features = ["rt", "sync", "time", "test-util"] }
 tokio-stream = { version = "0.1.1", path = "../tokio-stream" }
-async-stream = "0.3"
+async-stream = "0.3.3"
 
 bytes = "1.0.0"
 futures-core = "0.3.0"

tokio-test/LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2022 Tokio Contributors
+Copyright (c) 2023 Tokio Contributors
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated

tokio-test/src/io.rs

@@ -74,7 +74,7 @@ struct Inner {
 }
 
 impl Builder {
-    /// Return a new, empty `Builder.
+    /// Return a new, empty `Builder`.
     pub fn new() -> Self {
         Self::default()
     }
@@ -310,6 +310,8 @@ impl Inner {
 
                         if now < until {
                             break;
+                        } else {
+                            self.waiting = None;
                         }
                     } else {
                         self.waiting = Some(Instant::now() + *dur);
@@ -407,6 +409,20 @@ impl AsyncWrite for Mock {
             // If a sleep is set, it has already fired
             self.inner.sleep = None;
 
+            if self.inner.actions.is_empty() {
+                match self.inner.poll_action(cx) {
+                    Poll::Pending => {
+                        // do not propagate pending
+                    }
+                    Poll::Ready(Some(action)) => {
+                        self.inner.actions.push_back(action);
+                    }
+                    Poll::Ready(None) => {
+                        panic!("unexpected write");
+                    }
+                }
+            }
+
             match self.inner.write(buf) {
                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
                     if let Some(rem) = self.inner.remaining_wait() {
@@ -462,7 +478,7 @@ impl Drop for Mock {
             Action::Read(data) => assert!(data.is_empty(), "There is still data left to read."),
             Action::Write(data) => assert!(data.is_empty(), "There is still data left to write."),
             _ => (),
-        })
+        });
     }
 }
 /*

tokio-test/src/lib.rs

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

tokio-test/src/macros.rs

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

tokio-test/src/stream_mock.rs

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

tokio-test/src/task.rs

@@ -127,7 +127,7 @@ impl<T: Future> Spawn<T> {
 }
 
 impl<T: Stream> Spawn<T> {
-    /// If `T` is a [`Stream`] then poll_next it. This will handle pinning and the context
+    /// If `T` is a [`Stream`] then `poll_next` it. This will handle pinning and the context
     /// type for the stream.
     pub fn poll_next(&mut self) -> Poll<Option<T::Item>> {
         let stream = self.future.as_mut();

tokio-test/tests/io.rs

@@ -2,6 +2,7 @@
 
 use std::io;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tokio::time::{Duration, Instant};
 use tokio_test::io::Builder;
 
 #[tokio::test]
@@ -50,6 +51,29 @@ async fn write() {
     mock.write_all(b"world!").await.expect("write 2");
 }
 
+#[tokio::test]
+async fn write_with_handle() {
+    let (mut mock, mut handle) = Builder::new().build_with_handle();
+    handle.write(b"hello ");
+    handle.write(b"world!");
+
+    mock.write_all(b"hello ").await.expect("write 1");
+    mock.write_all(b"world!").await.expect("write 2");
+}
+
+#[tokio::test]
+async fn read_with_handle() {
+    let (mut mock, mut handle) = Builder::new().build_with_handle();
+    handle.read(b"hello ");
+    handle.read(b"world!");
+
+    let mut buf = vec![0; 6];
+    mock.read_exact(&mut buf).await.expect("read 1");
+    assert_eq!(&buf[..], b"hello ");
+    mock.read_exact(&mut buf).await.expect("read 2");
+    assert_eq!(&buf[..], b"world!");
+}
+
 #[tokio::test]
 async fn write_error() {
     let error = io::Error::new(io::ErrorKind::Other, "cruel");
@@ -84,3 +108,65 @@ async fn mock_panics_write_data_left() {
     use tokio_test::io::Builder;
     Builder::new().write(b"write").build();
 }
+
+#[tokio::test(start_paused = true)]
+async fn wait() {
+    const FIRST_WAIT: Duration = Duration::from_secs(1);
+
+    let mut mock = Builder::new()
+        .wait(FIRST_WAIT)
+        .read(b"hello ")
+        .read(b"world!")
+        .build();
+
+    let mut buf = [0; 256];
+
+    let start = Instant::now(); // record the time the read call takes
+                                //
+    let n = mock.read(&mut buf).await.expect("read 1");
+    assert_eq!(&buf[..n], b"hello ");
+    println!("time elapsed after first read {:?}", start.elapsed());
+
+    let n = mock.read(&mut buf).await.expect("read 2");
+    assert_eq!(&buf[..n], b"world!");
+    println!("time elapsed after second read {:?}", start.elapsed());
+
+    // make sure the .wait() instruction worked
+    assert!(
+        start.elapsed() >= FIRST_WAIT,
+        "consuming the whole mock only took {}ms",
+        start.elapsed().as_millis()
+    );
+}
+
+#[tokio::test(start_paused = true)]
+async fn multiple_wait() {
+    const FIRST_WAIT: Duration = Duration::from_secs(1);
+    const SECOND_WAIT: Duration = Duration::from_secs(1);
+
+    let mut mock = Builder::new()
+        .wait(FIRST_WAIT)
+        .read(b"hello ")
+        .wait(SECOND_WAIT)
+        .read(b"world!")
+        .build();
+
+    let mut buf = [0; 256];
+
+    let start = Instant::now(); // record the time it takes to consume the mock
+
+    let n = mock.read(&mut buf).await.expect("read 1");
+    assert_eq!(&buf[..n], b"hello ");
+    println!("time elapsed after first read {:?}", start.elapsed());
+
+    let n = mock.read(&mut buf).await.expect("read 2");
+    assert_eq!(&buf[..n], b"world!");
+    println!("time elapsed after second read {:?}", start.elapsed());
+
+    // make sure the .wait() instruction worked
+    assert!(
+        start.elapsed() >= FIRST_WAIT + SECOND_WAIT,
+        "consuming the whole mock only took {}ms",
+        start.elapsed().as_millis()
+    );
+}

tokio-test/tests/stream_mock.rs

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

tokio-util/CHANGELOG.md

@@ -1,3 +1,124 @@
+# 0.7.10 (October 24th, 2023)
+
+### Added
+
+- task: add `TaskTracker` ([#6033])
+- task: add `JoinMap::keys` ([#6046])
+- io: implement `Seek` for `SyncIoBridge` ([#6058])
+
+### Changed
+
+- deps: update hashbrown to 0.14 ([#6102])
+
+[#6033]: https://github.com/tokio-rs/tokio/pull/6033
+[#6046]: https://github.com/tokio-rs/tokio/pull/6046
+[#6058]: https://github.com/tokio-rs/tokio/pull/6058
+[#6102]: https://github.com/tokio-rs/tokio/pull/6102
+
+# 0.7.9 (September 20th, 2023)
+
+### Added
+
+- io: add passthrough `AsyncRead`/`AsyncWrite` to `InspectWriter`/`InspectReader` ([#5739])
+- task: add spawn blocking methods to `JoinMap` ([#5797])
+- io: pass through traits for `StreamReader` and `SinkWriter` ([#5941])
+- io: add `SyncIoBridge::into_inner` ([#5971])
+
+### Fixed
+
+- sync: handle possibly dangling reference safely ([#5812])
+- util: fix broken intra-doc link ([#5849])
+- compat: fix clippy warnings ([#5891])
+
+### Documented
+
+- codec: Specify the line ending of `LinesCodec` ([#5982])
+
+[#5739]: https://github.com/tokio-rs/tokio/pull/5739
+[#5797]: https://github.com/tokio-rs/tokio/pull/5797
+[#5941]: https://github.com/tokio-rs/tokio/pull/5941
+[#5971]: https://github.com/tokio-rs/tokio/pull/5971
+[#5812]: https://github.com/tokio-rs/tokio/pull/5812
+[#5849]: https://github.com/tokio-rs/tokio/pull/5849
+[#5891]: https://github.com/tokio-rs/tokio/pull/5891
+[#5982]: https://github.com/tokio-rs/tokio/pull/5982
+
+# 0.7.8 (April 25th, 2023)
+
+This release bumps the MSRV of tokio-util to 1.56.
+
+### Added
+
+- time: add `DelayQueue::peek` ([#5569])
+
+### Changed
+
+This release contains one performance improvement:
+
+- sync: try to lock the parent first in `CancellationToken` ([#5561])
+
+### Fixed
+
+- time: fix panic in `DelayQueue` ([#5630])
+
+### Documented
+
+- sync: improve `CancellationToken` doc on child tokens ([#5632])
+
+[#5561]: https://github.com/tokio-rs/tokio/pull/5561
+[#5569]: https://github.com/tokio-rs/tokio/pull/5569
+[#5630]: https://github.com/tokio-rs/tokio/pull/5630
+[#5632]: https://github.com/tokio-rs/tokio/pull/5632
+
+# 0.7.7 (February 12, 2023)
+
+This release reverts the removal of the `Encoder` bound on the `FramedParts`
+constructor from [#5280] since it turned out to be a breaking change. ([#5450])
+
+[#5450]: https://github.com/tokio-rs/tokio/pull/5450
+
+# 0.7.6 (February 10, 2023)
+
+This release fixes a compilation failure in 0.7.5 when it is used together with
+Tokio version 1.21 and unstable features are enabled. ([#5445])
+
+[#5445]: https://github.com/tokio-rs/tokio/pull/5445
+
+# 0.7.5 (February 9, 2023)
+
+This release fixes an accidental breaking change where `UnwindSafe` was
+accidentally removed from `CancellationToken`.
+
+### Added
+- codec: add `Framed::backpressure_boundary` ([#5124])
+- io: add `InspectReader` and `InspectWriter` ([#5033])
+- io: add `tokio_util::io::{CopyToBytes, SinkWriter}` ([#5070], [#5436])
+- io: impl `std::io::BufRead` on `SyncIoBridge` ([#5265])
+- sync: add `PollSemaphore::poll_acquire_many` ([#5137])
+- sync: add owned future for `CancellationToken` ([#5153])
+- time: add `DelayQueue::try_remove` ([#5052])
+
+### Fixed
+- codec: fix `LengthDelimitedCodec` buffer over-reservation ([#4997])
+- sync: impl `UnwindSafe` on `CancellationToken` ([#5438])
+- util: remove `Encoder` bound on `FramedParts` constructor ([#5280])
+
+### Documented
+- io: add lines example for `StreamReader` ([#5145])
+
+[#4997]: https://github.com/tokio-rs/tokio/pull/4997
+[#5033]: https://github.com/tokio-rs/tokio/pull/5033
+[#5052]: https://github.com/tokio-rs/tokio/pull/5052
+[#5070]: https://github.com/tokio-rs/tokio/pull/5070
+[#5124]: https://github.com/tokio-rs/tokio/pull/5124
+[#5137]: https://github.com/tokio-rs/tokio/pull/5137
+[#5145]: https://github.com/tokio-rs/tokio/pull/5145
+[#5153]: https://github.com/tokio-rs/tokio/pull/5153
+[#5265]: https://github.com/tokio-rs/tokio/pull/5265
+[#5280]: https://github.com/tokio-rs/tokio/pull/5280
+[#5436]: https://github.com/tokio-rs/tokio/pull/5436
+[#5438]: https://github.com/tokio-rs/tokio/pull/5438
+
 # 0.7.4 (September 8, 2022)
 
 ### Added

tokio-util/Cargo.toml

@@ -4,9 +4,9 @@ name = "tokio-util"
 # - Remove path dependencies
 # - Update CHANGELOG.md.
 # - Create "tokio-util-0.7.x" git tag.
-version = "0.7.4"
-edition = "2018"
-rust-version = "1.49"
+version = "0.7.10"
+edition = "2021"
+rust-version = "1.63"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
@@ -34,18 +34,18 @@ rt = ["tokio/rt", "tokio/sync", "futures-util", "hashbrown"]
 __docs_rs = ["futures-util"]
 
 [dependencies]
-tokio = { version = "1.21.0", path = "../tokio", features = ["sync"] }
+tokio = { version = "1.28.0", path = "../tokio", features = ["sync"] }
 bytes = "1.0.0"
 futures-core = "0.3.0"
 futures-sink = "0.3.0"
 futures-io = { version = "0.3.0", optional = true }
 futures-util = { version = "0.3.0", optional = true }
-pin-project-lite = "0.2.0"
+pin-project-lite = "0.2.11"
 slab = { version = "0.4.4", optional = true } # Backs `DelayQueue`
 tracing = { version = "0.1.25", default-features = false, features = ["std"], optional = true }
 
 [target.'cfg(tokio_unstable)'.dependencies]
-hashbrown = { version = "0.12.0", optional = true }
+hashbrown = { version = "0.14.0", optional = true }
 
 [dev-dependencies]
 tokio = { version = "1.0.0", path = "../tokio", features = ["full"] }
@@ -56,6 +56,7 @@ async-stream = "0.3.0"
 futures = "0.3.0"
 futures-test = "0.3.5"
 parking_lot = "0.12.0"
+tempfile = "3.1.0"
 
 [package.metadata.docs.rs]
 all-features = true

tokio-util/LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2022 Tokio Contributors
+Copyright (c) 2023 Tokio Contributors
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated

tokio-util/src/codec/lines_codec.rs

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

tokio-util/src/compat.rs

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

tokio-util/src/either.rs

@@ -116,7 +116,7 @@ where
     }
 
     fn consume(self: Pin<&mut Self>, amt: usize) {
-        delegate_call!(self.consume(amt))
+        delegate_call!(self.consume(amt));
     }
 }
 

tokio-util/src/io/copy_to_bytes.rs

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

tokio-util/src/io/inspect.rs

@@ -52,6 +52,42 @@ impl<R: AsyncRead, F: FnMut(&[u8])> AsyncRead for InspectReader<R, F> {
     }
 }
 
+impl<R: AsyncWrite, F> AsyncWrite for InspectReader<R, F> {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<std::result::Result<usize, std::io::Error>> {
+        self.project().reader.poll_write(cx, buf)
+    }
+
+    fn poll_flush(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<std::result::Result<(), std::io::Error>> {
+        self.project().reader.poll_flush(cx)
+    }
+
+    fn poll_shutdown(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<std::result::Result<(), std::io::Error>> {
+        self.project().reader.poll_shutdown(cx)
+    }
+
+    fn poll_write_vectored(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[IoSlice<'_>],
+    ) -> Poll<Result<usize>> {
+        self.project().reader.poll_write_vectored(cx, bufs)
+    }
+
+    fn is_write_vectored(&self) -> bool {
+        self.reader.is_write_vectored()
+    }
+}
+
 pin_project! {
     /// An adapter that lets you inspect the data that's being written.
     ///
@@ -132,3 +168,13 @@ impl<W: AsyncWrite, F: FnMut(&[u8])> AsyncWrite for InspectWriter<W, F> {
         self.writer.is_write_vectored()
     }
 }
+
+impl<W: AsyncRead, F> AsyncRead for InspectWriter<W, F> {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<std::io::Result<()>> {
+        self.project().writer.poll_read(cx, buf)
+    }
+}

tokio-util/src/io/sink_writer.rs

@@ -1,10 +1,12 @@
+use futures_core::ready;
 use futures_sink::Sink;
 
+use futures_core::stream::Stream;
 use pin_project_lite::pin_project;
 use std::io;
 use std::pin::Pin;
 use std::task::{Context, Poll};
-use tokio::io::AsyncWrite;
+use tokio::io::{AsyncRead, AsyncWrite};
 
 pin_project! {
     /// Convert a [`Sink`] of byte chunks into an [`AsyncWrite`].
@@ -58,7 +60,7 @@ pin_project! {
     /// [`CopyToBytes`]: crate::io::CopyToBytes
     /// [`Encoder`]: crate::codec::Encoder
     /// [`Sink`]: futures_sink::Sink
-    /// [`codec`]: tokio_util::codec
+    /// [`codec`]: crate::codec
     #[derive(Debug)]
     pub struct SinkWriter<S> {
         #[pin]
@@ -98,19 +100,11 @@ where
         buf: &[u8],
     ) -> Poll<Result<usize, io::Error>> {
         let mut this = self.project();
-        match this.inner.as_mut().poll_ready(cx) {
-            Poll::Ready(Ok(())) => {
-                if let Err(e) = this.inner.as_mut().start_send(buf) {
-                    Poll::Ready(Err(e.into()))
-                } else {
-                    Poll::Ready(Ok(buf.len()))
-                }
-            }
-            Poll::Ready(Err(e)) => Poll::Ready(Err(e.into())),
-            Poll::Pending => {
-                cx.waker().wake_by_ref();
-                Poll::Pending
-            }
+
+        ready!(this.inner.as_mut().poll_ready(cx).map_err(Into::into))?;
+        match this.inner.as_mut().start_send(buf) {
+            Ok(()) => Poll::Ready(Ok(buf.len())),
+            Err(e) => Poll::Ready(Err(e.into())),
         }
     }
 
@@ -122,3 +116,20 @@ where
         self.project().inner.poll_close(cx).map_err(Into::into)
     }
 }
+
+impl<S: Stream> Stream for SinkWriter<S> {
+    type Item = S::Item;
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        self.project().inner.poll_next(cx)
+    }
+}
+
+impl<S: AsyncRead> AsyncRead for SinkWriter<S> {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut tokio::io::ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        self.project().inner.poll_read(cx, buf)
+    }
+}

tokio-util/src/io/stream_reader.rs

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

tokio-util/src/io/sync_bridge.rs

@@ -1,5 +1,8 @@
-use std::io::{Read, Write};
-use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
+use std::io::{BufRead, Read, Seek, Write};
+use tokio::io::{
+    AsyncBufRead, AsyncBufReadExt, AsyncRead, AsyncReadExt, AsyncSeek, AsyncSeekExt, AsyncWrite,
+    AsyncWriteExt,
+};
 
 /// Use a [`tokio::io::AsyncRead`] synchronously as a [`std::io::Read`] or
 /// a [`tokio::io::AsyncWrite`] as a [`std::io::Write`].
@@ -9,6 +12,28 @@ pub struct SyncIoBridge<T> {
     rt: tokio::runtime::Handle,
 }
 
+impl<T: AsyncBufRead + Unpin> BufRead for SyncIoBridge<T> {
+    fn fill_buf(&mut self) -> std::io::Result<&[u8]> {
+        let src = &mut self.src;
+        self.rt.block_on(AsyncBufReadExt::fill_buf(src))
+    }
+
+    fn consume(&mut self, amt: usize) {
+        let src = &mut self.src;
+        AsyncBufReadExt::consume(src, amt)
+    }
+
+    fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> std::io::Result<usize> {
+        let src = &mut self.src;
+        self.rt
+            .block_on(AsyncBufReadExt::read_until(src, byte, buf))
+    }
+    fn read_line(&mut self, buf: &mut String) -> std::io::Result<usize> {
+        let src = &mut self.src;
+        self.rt.block_on(AsyncBufReadExt::read_line(src, buf))
+    }
+}
+
 impl<T: AsyncRead + Unpin> Read for SyncIoBridge<T> {
     fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
         let src = &mut self.src;
@@ -55,6 +80,13 @@ impl<T: AsyncWrite + Unpin> Write for SyncIoBridge<T> {
     }
 }
 
+impl<T: AsyncSeek + Unpin> Seek for SyncIoBridge<T> {
+    fn seek(&mut self, pos: std::io::SeekFrom) -> std::io::Result<u64> {
+        let src = &mut self.src;
+        self.rt.block_on(AsyncSeekExt::seek(src, pos))
+    }
+}
+
 // Because https://doc.rust-lang.org/std/io/trait.Write.html#method.is_write_vectored is at the time
 // of this writing still unstable, we expose this as part of a standalone method.
 impl<T: AsyncWrite> SyncIoBridge<T> {
@@ -116,4 +148,9 @@ impl<T: Unpin> SyncIoBridge<T> {
     pub fn new_with_handle(src: T, rt: tokio::runtime::Handle) -> Self {
         Self { src, rt }
     }
+
+    /// Consume this bridge, returning the underlying stream.
+    pub fn into_inner(self) -> T {
+        self.src
+    }
 }

tokio-util/src/lib.rs

@@ -55,151 +55,6 @@ pub mod sync;
 
 pub mod either;
 
-#[cfg(any(feature = "io", feature = "codec"))]
-mod util {
-    use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
+pub use bytes;
 
-    use bytes::{Buf, BufMut};
-    use futures_core::ready;
-    use std::io::{self, IoSlice};
-    use std::mem::MaybeUninit;
-    use std::pin::Pin;
-    use std::task::{Context, Poll};
-
-    /// Try to read data from an `AsyncRead` into an implementer of the [`BufMut`] trait.
-    ///
-    /// [`BufMut`]: bytes::Buf
-    ///
-    /// # Example
-    ///
-    /// ```
-    /// use bytes::{Bytes, BytesMut};
-    /// use tokio_stream as stream;
-    /// use tokio::io::Result;
-    /// use tokio_util::io::{StreamReader, poll_read_buf};
-    /// use futures::future::poll_fn;
-    /// use std::pin::Pin;
-    /// # #[tokio::main]
-    /// # async fn main() -> std::io::Result<()> {
-    ///
-    /// // Create a reader from an iterator. This particular reader will always be
-    /// // ready.
-    /// let mut read = StreamReader::new(stream::iter(vec![Result::Ok(Bytes::from_static(&[0, 1, 2, 3]))]));
-    ///
-    /// let mut buf = BytesMut::new();
-    /// let mut reads = 0;
-    ///
-    /// loop {
-    ///     reads += 1;
-    ///     let n = poll_fn(|cx| poll_read_buf(Pin::new(&mut read), cx, &mut buf)).await?;
-    ///
-    ///     if n == 0 {
-    ///         break;
-    ///     }
-    /// }
-    ///
-    /// // one or more reads might be necessary.
-    /// assert!(reads >= 1);
-    /// assert_eq!(&buf[..], &[0, 1, 2, 3]);
-    /// # Ok(())
-    /// # }
-    /// ```
-    #[cfg_attr(not(feature = "io"), allow(unreachable_pub))]
-    pub fn poll_read_buf<T: AsyncRead, B: BufMut>(
-        io: Pin<&mut T>,
-        cx: &mut Context<'_>,
-        buf: &mut B,
-    ) -> Poll<io::Result<usize>> {
-        if !buf.has_remaining_mut() {
-            return Poll::Ready(Ok(0));
-        }
-
-        let n = {
-            let dst = buf.chunk_mut();
-
-            // Safety: `chunk_mut()` returns a `&mut UninitSlice`, and `UninitSlice` is a
-            // transparent wrapper around `[MaybeUninit<u8>]`.
-            let dst = unsafe { &mut *(dst as *mut _ as *mut [MaybeUninit<u8>]) };
-            let mut buf = ReadBuf::uninit(dst);
-            let ptr = buf.filled().as_ptr();
-            ready!(io.poll_read(cx, &mut buf)?);
-
-            // Ensure the pointer does not change from under us
-            assert_eq!(ptr, buf.filled().as_ptr());
-            buf.filled().len()
-        };
-
-        // Safety: This is guaranteed to be the number of initialized (and read)
-        // bytes due to the invariants provided by `ReadBuf::filled`.
-        unsafe {
-            buf.advance_mut(n);
-        }
-
-        Poll::Ready(Ok(n))
-    }
-
-    /// Try to write data from an implementer of the [`Buf`] trait to an
-    /// [`AsyncWrite`], advancing the buffer's internal cursor.
-    ///
-    /// This function will use [vectored writes] when the [`AsyncWrite`] supports
-    /// vectored writes.
-    ///
-    /// # Examples
-    ///
-    /// [`File`] implements [`AsyncWrite`] and [`Cursor<&[u8]>`] implements
-    /// [`Buf`]:
-    ///
-    /// ```no_run
-    /// use tokio_util::io::poll_write_buf;
-    /// use tokio::io;
-    /// use tokio::fs::File;
-    ///
-    /// use bytes::Buf;
-    /// use std::io::Cursor;
-    /// use std::pin::Pin;
-    /// use futures::future::poll_fn;
-    ///
-    /// #[tokio::main]
-    /// async fn main() -> io::Result<()> {
-    ///     let mut file = File::create("foo.txt").await?;
-    ///     let mut buf = Cursor::new(b"data to write");
-    ///
-    ///     // Loop until the entire contents of the buffer are written to
-    ///     // the file.
-    ///     while buf.has_remaining() {
-    ///         poll_fn(|cx| poll_write_buf(Pin::new(&mut file), cx, &mut buf)).await?;
-    ///     }
-    ///
-    ///     Ok(())
-    /// }
-    /// ```
-    ///
-    /// [`Buf`]: bytes::Buf
-    /// [`AsyncWrite`]: tokio::io::AsyncWrite
-    /// [`File`]: tokio::fs::File
-    /// [vectored writes]: tokio::io::AsyncWrite::poll_write_vectored
-    #[cfg_attr(not(feature = "io"), allow(unreachable_pub))]
-    pub fn poll_write_buf<T: AsyncWrite, B: Buf>(
-        io: Pin<&mut T>,
-        cx: &mut Context<'_>,
-        buf: &mut B,
-    ) -> Poll<io::Result<usize>> {
-        const MAX_BUFS: usize = 64;
-
-        if !buf.has_remaining() {
-            return Poll::Ready(Ok(0));
-        }
-
-        let n = if io.is_write_vectored() {
-            let mut slices = [IoSlice::new(&[]); MAX_BUFS];
-            let cnt = buf.chunks_vectored(&mut slices);
-            ready!(io.poll_write_vectored(cx, &slices[..cnt]))?
-        } else {
-            ready!(io.poll_write(cx, buf.chunk()))?
-        };
-
-        buf.advance(n);
-
-        Poll::Ready(Ok(n))
-    }
-}
+mod util;

tokio-util/src/sync/cancellation_token.rs

@@ -4,6 +4,7 @@ pub(crate) mod guard;
 mod tree_node;
 
 use crate::loom::sync::Arc;
+use crate::util::MaybeDangling;
 use core::future::Future;
 use core::pin::Pin;
 use core::task::{Context, Poll};
@@ -55,6 +56,9 @@ pub struct CancellationToken {
     inner: Arc<tree_node::TreeNode>,
 }
 
+impl std::panic::UnwindSafe for CancellationToken {}
+impl std::panic::RefUnwindSafe for CancellationToken {}
+
 pin_project! {
     /// A Future that is resolved once the corresponding [`CancellationToken`]
     /// is cancelled.
@@ -74,11 +78,23 @@ pin_project! {
     /// [`CancellationToken`] by value instead of using a reference.
     #[must_use = "futures do nothing unless polled"]
     pub struct WaitForCancellationFutureOwned {
-        // Since `future` is the first field, it is dropped before the
-        // cancellation_token field. This ensures that the reference inside the
-        // `Notified` remains valid.
+        // This field internally has a reference to the cancellation token, but camouflages
+        // the relationship with `'static`. To avoid Undefined Behavior, we must ensure
+        // that the reference is only used while the cancellation token is still alive. To
+        // do that, we ensure that the future is the first field, so that it is dropped
+        // before the cancellation token.
+        //
+        // We use `MaybeDanglingFuture` here because without it, the compiler could assert
+        // the reference inside `future` to be valid even after the destructor of that
+        // field runs. (Specifically, when the `WaitForCancellationFutureOwned` is passed
+        // as an argument to a function, the reference can be asserted to be valid for the
+        // rest of that function.) To avoid that, we use `MaybeDangling` which tells the
+        // compiler that the reference stored inside it might not be valid.
+        //
+        // See <https://users.rust-lang.org/t/unsafe-code-review-semi-owning-weak-rwlock-t-guard/95706>
+        // for more info.
         #[pin]
-        future: tokio::sync::futures::Notified<'static>,
+        future: MaybeDangling<tokio::sync::futures::Notified<'static>>,
         cancellation_token: CancellationToken,
     }
 }
@@ -94,6 +110,8 @@ impl core::fmt::Debug for CancellationToken {
 }
 
 impl Clone for CancellationToken {
+    /// Creates a clone of the `CancellationToken` which will get cancelled
+    /// whenever the current token gets cancelled, and vice versa.
     fn clone(&self) -> Self {
         tree_node::increase_handle_refcount(&self.inner);
         CancellationToken {
@@ -115,7 +133,7 @@ impl Default for CancellationToken {
 }
 
 impl CancellationToken {
-    /// Creates a new CancellationToken in the non-cancelled state.
+    /// Creates a new `CancellationToken` in the non-cancelled state.
     pub fn new() -> CancellationToken {
         CancellationToken {
             inner: Arc::new(tree_node::TreeNode::new()),
@@ -123,7 +141,8 @@ impl CancellationToken {
     }
 
     /// Creates a `CancellationToken` which will get cancelled whenever the
-    /// current token gets cancelled.
+    /// current token gets cancelled. Unlike a cloned `CancellationToken`,
+    /// cancelling a child token does not cancel the parent token.
     ///
     /// If the current token is already cancelled, the child token will get
     /// returned in cancelled state.
@@ -273,7 +292,7 @@ impl WaitForCancellationFutureOwned {
             // # Safety
             //
             // cancellation_token is dropped after future due to the field ordering.
-            future: unsafe { Self::new_future(&cancellation_token) },
+            future: MaybeDangling::new(unsafe { Self::new_future(&cancellation_token) }),
             cancellation_token,
         }
     }
@@ -314,8 +333,9 @@ impl Future for WaitForCancellationFutureOwned {
             // # Safety
             //
             // cancellation_token is dropped after future due to the field ordering.
-            this.future
-                .set(unsafe { Self::new_future(this.cancellation_token) });
+            this.future.set(MaybeDangling::new(unsafe {
+                Self::new_future(this.cancellation_token)
+            }));
         }
     }
 }

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

@@ -1,12 +1,12 @@
 //! This mod provides the logic for the inner tree structure of the CancellationToken.
 //!
-//! CancellationTokens are only light handles with references to TreeNode.
-//! All the logic is actually implemented in the TreeNode.
+//! CancellationTokens are only light handles with references to [`TreeNode`].
+//! All the logic is actually implemented in the [`TreeNode`].
 //!
-//! A TreeNode is part of the cancellation tree and may have one parent and an arbitrary number of
+//! A [`TreeNode`] is part of the cancellation tree and may have one parent and an arbitrary number of
 //! children.
 //!
-//! A TreeNode can receive the request to perform a cancellation through a CancellationToken.
+//! A [`TreeNode`] can receive the request to perform a cancellation through a CancellationToken.
 //! This cancellation request will cancel the node and all of its descendants.
 //!
 //! As soon as a node cannot get cancelled any more (because it was already cancelled or it has no
@@ -151,47 +151,43 @@ fn with_locked_node_and_parent<F, Ret>(node: &Arc<TreeNode>, func: F) -> Ret
 where
     F: FnOnce(MutexGuard<'_, Inner>, Option<MutexGuard<'_, Inner>>) -> Ret,
 {
-    let mut potential_parent = {
-        let locked_node = node.inner.lock().unwrap();
-        match locked_node.parent.clone() {
-            Some(parent) => parent,
-            // If we locked the node and its parent is `None`, we are in a valid state
-            // and can return.
-            None => return func(locked_node, None),
-        }
-    };
+    use std::sync::TryLockError;
 
+    let mut locked_node = node.inner.lock().unwrap();
+
+    // Every time this fails, the number of ancestors of the node decreases,
+    // so the loop must succeed after a finite number of iterations.
     loop {
-        // Deadlock safety:
-        //
-        // Due to invariant #2, we know that we have to lock the parent first, and then the child.
-        // This is true even if the potential_parent is no longer the current parent or even its
-        // sibling, as the invariant still holds.
-        let locked_parent = potential_parent.inner.lock().unwrap();
-        let locked_node = node.inner.lock().unwrap();
-
-        let actual_parent = match locked_node.parent.clone() {
-            Some(parent) => parent,
-            // If we locked the node and its parent is `None`, we are in a valid state
-            // and can return.
-            None => {
-                // Was the wrong parent, so unlock it before calling `func`
-                drop(locked_parent);
-                return func(locked_node, None);
-            }
+        // Look up the parent of the currently locked node.
+        let potential_parent = match locked_node.parent.as_ref() {
+            Some(potential_parent) => potential_parent.clone(),
+            None => return func(locked_node, None),
         };
 
-        // Loop until we managed to lock both the node and its parent
-        if Arc::ptr_eq(&actual_parent, &potential_parent) {
-            return func(locked_node, Some(locked_parent));
+        // Lock the parent. This may require unlocking the child first.
+        let locked_parent = match potential_parent.inner.try_lock() {
+            Ok(locked_parent) => locked_parent,
+            Err(TryLockError::WouldBlock) => {
+                drop(locked_node);
+                // Deadlock safety:
+                //
+                // Due to invariant #2, the potential parent must come before
+                // the child in the creation order. Therefore, we can safely
+                // lock the child while holding the parent lock.
+                let locked_parent = potential_parent.inner.lock().unwrap();
+                locked_node = node.inner.lock().unwrap();
+                locked_parent
+            }
+            Err(TryLockError::Poisoned(err)) => Err(err).unwrap(),
+        };
+
+        // If we unlocked the child, then the parent may have changed. Check
+        // that we still have the right parent.
+        if let Some(actual_parent) = locked_node.parent.as_ref() {
+            if Arc::ptr_eq(actual_parent, &potential_parent) {
+                return func(locked_node, Some(locked_parent));
+            }
         }
-
-        // Drop locked_parent before reassigning to potential_parent,
-        // as potential_parent is borrowed in it
-        drop(locked_node);
-        drop(locked_parent);
-
-        potential_parent = actual_parent;
     }
 }
 
@@ -243,11 +239,7 @@ fn remove_child(parent: &mut Inner, mut node: MutexGuard<'_, Inner>) {
 
     let len = parent.children.len();
     if 4 * len <= parent.children.capacity() {
-        // equal to:
-        //    parent.children.shrink_to(2 * len);
-        // but shrink_to was not yet stabilized in our minimal compatible version
-        let old_children = std::mem::replace(&mut parent.children, Vec::with_capacity(2 * len));
-        parent.children.extend(old_children);
+        parent.children.shrink_to(2 * len);
     }
 }
 

tokio-util/src/sync/mpsc.rs

@@ -44,7 +44,7 @@ enum State<T> {
 pub struct PollSender<T> {
     sender: Option<Sender<T>>,
     state: State<T>,
-    acquire: ReusableBoxFuture<'static, Result<OwnedPermit<T>, PollSendError<T>>>,
+    acquire: PollSenderFuture<T>,
 }
 
 // Creates a future for acquiring a permit from the underlying channel.  This is used to ensure
@@ -64,13 +64,56 @@ async fn make_acquire_future<T>(
     }
 }
 
-impl<T: Send + 'static> PollSender<T> {
+type InnerFuture<'a, T> = ReusableBoxFuture<'a, Result<OwnedPermit<T>, PollSendError<T>>>;
+
+#[derive(Debug)]
+// TODO: This should be replace with a type_alias_impl_trait to eliminate `'static` and all the transmutes
+struct PollSenderFuture<T>(InnerFuture<'static, T>);
+
+impl<T> PollSenderFuture<T> {
+    /// Create with an empty inner future with no `Send` bound.
+    fn empty() -> Self {
+        // We don't use `make_acquire_future` here because our relaxed bounds on `T` are not
+        // compatible with the transitive bounds required by `Sender<T>`.
+        Self(ReusableBoxFuture::new(async { unreachable!() }))
+    }
+}
+
+impl<T: Send> PollSenderFuture<T> {
+    /// Create with an empty inner future.
+    fn new() -> Self {
+        let v = InnerFuture::new(make_acquire_future(None));
+        // This is safe because `make_acquire_future(None)` is actually `'static`
+        Self(unsafe { mem::transmute::<InnerFuture<'_, T>, InnerFuture<'static, T>>(v) })
+    }
+
+    /// Poll the inner future.
+    fn poll(&mut self, cx: &mut Context<'_>) -> Poll<Result<OwnedPermit<T>, PollSendError<T>>> {
+        self.0.poll(cx)
+    }
+
+    /// Replace the inner future.
+    fn set(&mut self, sender: Option<Sender<T>>) {
+        let inner: *mut InnerFuture<'static, T> = &mut self.0;
+        let inner: *mut InnerFuture<'_, T> = inner.cast();
+        // SAFETY: The `make_acquire_future(sender)` future must not exist after the type `T`
+        // becomes invalid, and this casts away the type-level lifetime check for that. However, the
+        // inner future is never moved out of this `PollSenderFuture<T>`, so the future will not
+        // live longer than the `PollSenderFuture<T>` lives. A `PollSenderFuture<T>` is guaranteed
+        // to not exist after the type `T` becomes invalid, because it is annotated with a `T`, so
+        // this is ok.
+        let inner = unsafe { &mut *inner };
+        inner.set(make_acquire_future(sender));
+    }
+}
+
+impl<T: Send> PollSender<T> {
     /// Creates a new `PollSender`.
     pub fn new(sender: Sender<T>) -> Self {
         Self {
             sender: Some(sender.clone()),
             state: State::Idle(sender),
-            acquire: ReusableBoxFuture::new(make_acquire_future(None)),
+            acquire: PollSenderFuture::new(),
         }
     }
 
@@ -97,7 +140,7 @@ impl<T: Send + 'static> PollSender<T> {
                 State::Idle(sender) => {
                     // Start trying to acquire a permit to reserve a slot for our send, and
                     // immediately loop back around to poll it the first time.
-                    self.acquire.set(make_acquire_future(Some(sender)));
+                    self.acquire.set(Some(sender));
                     (None, State::Acquiring)
                 }
                 State::Acquiring => match self.acquire.poll(cx) {
@@ -194,7 +237,7 @@ impl<T: Send + 'static> PollSender<T> {
         match self.state {
             State::Idle(_) => self.state = State::Closed,
             State::Acquiring => {
-                self.acquire.set(make_acquire_future(None));
+                self.acquire.set(None);
                 self.state = State::Closed;
             }
             _ => {}
@@ -215,7 +258,7 @@ impl<T: Send + 'static> PollSender<T> {
             // We're currently trying to reserve a slot to send into.
             State::Acquiring => {
                 // Replacing the future drops the in-flight one.
-                self.acquire.set(make_acquire_future(None));
+                self.acquire.set(None);
 
                 // If we haven't closed yet, we have to clone our stored sender since we have no way
                 // to get it back from the acquire future we just dropped.
@@ -255,9 +298,7 @@ impl<T> Clone for PollSender<T> {
         Self {
             sender,
             state,
-            // We don't use `make_acquire_future` here because our relaxed bounds on `T` are not
-            // compatible with the transitive bounds required by `Sender<T>`.
-            acquire: ReusableBoxFuture::new(async { unreachable!() }),
+            acquire: PollSenderFuture::empty(),
         }
     }
 }

tokio-util/src/sync/poll_semaphore.rs

@@ -29,7 +29,7 @@ impl PollSemaphore {
 
     /// Closes the semaphore.
     pub fn close(&self) {
-        self.semaphore.close()
+        self.semaphore.close();
     }
 
     /// Obtain a clone of the inner semaphore.
@@ -166,6 +166,6 @@ impl fmt::Debug for PollSemaphore {
 
 impl AsRef<Semaphore> for PollSemaphore {
     fn as_ref(&self) -> &Semaphore {
-        &*self.semaphore
+        &self.semaphore
     }
 }