chore: prepare Tokio v1.10.1

Fixes #4035

.clippy.toml

@@ -0,0 +1 @@
+msrv = "1.45"

.github/FUNDING.yml

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

.github/workflows/ci.yml

@@ -9,7 +9,7 @@ name: CI
 env:
   RUSTFLAGS: -Dwarnings
   RUST_BACKTRACE: 1
-  nightly: nightly-2021-04-25
+  nightly: nightly-2021-07-09
   minrust: 1.45.2
 
 jobs:
@@ -122,7 +122,7 @@ jobs:
 
       # Run `tokio` with "unstable" cfg flag.
       - name: test tokio full --cfg unstable
-        run: cargo test --features full
+        run: cargo test --all-features
         working-directory: tokio
         env:
           RUSTFLAGS: --cfg tokio_unstable -Dwarnings
@@ -238,7 +238,7 @@ jobs:
           cargo hack --remove-dev-deps --workspace
           # Update Cargo.lock to minimal version dependencies.
           cargo update -Z minimal-versions
-          cargo check --all-features
+          cargo hack check --all-features --ignore-private
 
   fmt:
     name: fmt
@@ -265,7 +265,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Install Rust
-        run: rustup update ${{ env.minrust }} && rustup default ${{ env.minrust }}
+        run: rustup update 1.52.1 && rustup default 1.52.1
       - name: Install clippy
         run: rustup component add clippy
 
@@ -286,6 +286,7 @@ jobs:
       - name: "doc --lib --all-features"
         run: cargo doc --lib --no-deps --all-features --document-private-items
         env:
+          RUSTFLAGS: --cfg docsrs
           RUSTDOCFLAGS: --cfg docsrs -Dwarnings
 
   loom:

README.md

@@ -56,7 +56,7 @@ Make sure you activated the full features of the tokio crate on Cargo.toml:
 
 ```toml
 [dependencies]
-tokio = { version = "1.5.0", features = ["full"] }
+tokio = { version = "1.10.1", features = ["full"] }
 ```
 Then, on your main.rs:
 
@@ -66,7 +66,7 @@ use tokio::io::{AsyncReadExt, AsyncWriteExt};
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let mut listener = TcpListener::bind("127.0.0.1:8080").await?;
+    let listener = TcpListener::bind("127.0.0.1:8080").await?;
 
     loop {
         let (mut socket, _) = listener.accept().await?;
@@ -140,8 +140,7 @@ several other libraries, including:
 
 * [`tower`]: A library of modular and reusable components for building robust networking clients and servers.
 
-* [`tracing`] (formerly `tokio-trace`): A framework for application-level
-  tracing and async-aware diagnostics.
+* [`tracing`] (formerly `tokio-trace`): A framework for application-level tracing and async-aware diagnostics.
 
 * [`rdbc`]: A Rust database connectivity library for MySQL, Postgres and SQLite.
 
@@ -164,9 +163,35 @@ several other libraries, including:
 
 ## Supported Rust Versions
 
-Tokio is built against the latest stable release. The minimum supported version is 1.45.
-The current Tokio version is not guaranteed to build on Rust versions earlier than the
-minimum supported version.
+Tokio is built against the latest stable release. The minimum supported version
+is 1.45.  The current Tokio version is not guaranteed to build on Rust versions
+earlier than the minimum supported version.
+
+## Release schedule
+
+Tokio doesn't follow a fixed release schedule, but we typically make one to two
+new minor releases each month. We make patch releases for bugfixes as necessary.
+
+## Bug patching policy
+
+For the purposes of making patch releases with bugfixes, we have designated
+certain minor releases as LTS (long term support) releases. Whenever a bug
+warrants a patch release with a fix for the bug, it will be backported and
+released as a new patch release for each LTS minor version. Our current LTS
+releases are:
+
+ * `1.8.x` - LTS release until February 2022.
+
+Each LTS release will continue to receive backported fixes for at least half a
+year. If you wish to use a fixed minor release in your project, we recommend
+that you use an LTS release.
+
+To use a fixed minor version, you can specify the version with a tilde. For
+example, to specify that you wish to use the newest `1.8.x` patch release, you
+can use the following dependency specification:
+```text
+tokio = { version = "~1.8", features = [...] }
+```
 
 ## License
 

benches/rt_multi_threaded.rs

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

benches/spawn.rs

@@ -2,63 +2,83 @@
 //! This essentially measure the time to enqueue a task in the local and remote
 //! case.
 
+#[macro_use]
+extern crate bencher;
+
 use bencher::{black_box, Bencher};
 
 async fn work() -> usize {
     let val = 1 + 1;
+    tokio::task::yield_now().await;
     black_box(val)
 }
 
-fn basic_scheduler_local_spawn(bench: &mut Bencher) {
+fn basic_scheduler_spawn(bench: &mut Bencher) {
     let runtime = tokio::runtime::Builder::new_current_thread()
         .build()
         .unwrap();
-    runtime.block_on(async {
-        bench.iter(|| {
-            let h = tokio::spawn(work());
-            black_box(h);
-        })
-    });
-}
-
-fn threaded_scheduler_local_spawn(bench: &mut Bencher) {
-    let runtime = tokio::runtime::Builder::new_current_thread()
-        .build()
-        .unwrap();
-    runtime.block_on(async {
-        bench.iter(|| {
-            let h = tokio::spawn(work());
-            black_box(h);
-        })
-    });
-}
-
-fn basic_scheduler_remote_spawn(bench: &mut Bencher) {
-    let runtime = tokio::runtime::Builder::new_current_thread()
-        .build()
-        .unwrap();
-
     bench.iter(|| {
-        let h = runtime.spawn(work());
-        black_box(h);
+        runtime.block_on(async {
+            let h = tokio::spawn(work());
+            assert_eq!(h.await.unwrap(), 2);
+        });
     });
 }
 
-fn threaded_scheduler_remote_spawn(bench: &mut Bencher) {
-    let runtime = tokio::runtime::Builder::new_multi_thread().build().unwrap();
-
+fn basic_scheduler_spawn10(bench: &mut Bencher) {
+    let runtime = tokio::runtime::Builder::new_current_thread()
+        .build()
+        .unwrap();
     bench.iter(|| {
-        let h = runtime.spawn(work());
-        black_box(h);
+        runtime.block_on(async {
+            let mut handles = Vec::with_capacity(10);
+            for _ in 0..10 {
+                handles.push(tokio::spawn(work()));
+            }
+            for handle in handles {
+                assert_eq!(handle.await.unwrap(), 2);
+            }
+        });
+    });
+}
+
+fn threaded_scheduler_spawn(bench: &mut Bencher) {
+    let runtime = tokio::runtime::Builder::new_multi_thread()
+        .worker_threads(1)
+        .build()
+        .unwrap();
+    bench.iter(|| {
+        runtime.block_on(async {
+            let h = tokio::spawn(work());
+            assert_eq!(h.await.unwrap(), 2);
+        });
+    });
+}
+
+fn threaded_scheduler_spawn10(bench: &mut Bencher) {
+    let runtime = tokio::runtime::Builder::new_multi_thread()
+        .worker_threads(1)
+        .build()
+        .unwrap();
+    bench.iter(|| {
+        runtime.block_on(async {
+            let mut handles = Vec::with_capacity(10);
+            for _ in 0..10 {
+                handles.push(tokio::spawn(work()));
+            }
+            for handle in handles {
+                assert_eq!(handle.await.unwrap(), 2);
+            }
+        });
     });
 }
 
 bencher::benchmark_group!(
     spawn,
-    basic_scheduler_local_spawn,
-    threaded_scheduler_local_spawn,
-    basic_scheduler_remote_spawn,
-    threaded_scheduler_remote_spawn
+    basic_scheduler_spawn,
+    basic_scheduler_spawn10,
+    threaded_scheduler_spawn,
+    threaded_scheduler_spawn10,
 );
 
 bencher::benchmark_main!(spawn);

examples/Cargo.toml

@@ -22,7 +22,10 @@ serde_json = "1.0"
 httparse = "1.0"
 time = "0.1"
 once_cell = "1.5.2"
+rand = "0.8.3"
 
+[target.'cfg(windows)'.dev-dependencies.winapi]
+version = "0.3.8"
 
 [[example]]
 name = "chat"
@@ -76,3 +79,15 @@ path = "custom-executor.rs"
 [[example]]
 name = "custom-executor-tokio-context"
 path = "custom-executor-tokio-context.rs"
+
+[[example]]
+name = "named-pipe"
+path = "named-pipe.rs"
+
+[[example]]
+name = "named-pipe-ready"
+path = "named-pipe-ready.rs"
+
+[[example]]
+name = "named-pipe-multi-client"
+path = "named-pipe-multi-client.rs"

examples/named-pipe-multi-client.rs

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

examples/named-pipe-ready.rs

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

examples/named-pipe.rs

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

tests-build/tests/fail/macros_core_no_default.stderr

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

tokio-macros/CHANGELOG.md

@@ -1,3 +1,19 @@
+# 1.3.0 (July 7, 2021)
+
+- macros: don't trigger `clippy::unwrap_used` ([#3926])
+
+[#3926]: https://github.com/tokio-rs/tokio/pull/3926
+
+# 1.2.0 (May 14, 2021)
+
+- macros: forward input arguments in `#[tokio::test]` ([#3691])
+- macros: improve diagnostics on type mismatch ([#3766])
+- macros: various error message improvements ([#3677])
+
+[#3677]: https://github.com/tokio-rs/tokio/pull/3677
+[#3691]: https://github.com/tokio-rs/tokio/pull/3691
+[#3766]: https://github.com/tokio-rs/tokio/pull/3766
+
 # 1.1.0 (February 5, 2021)
 
 - add `start_paused` option to macros ([#3492])

tokio-macros/Cargo.toml

@@ -6,13 +6,13 @@ name = "tokio-macros"
 #   - Cargo.toml
 # - Update CHANGELOG.md.
 # - Create "tokio-macros-1.0.x" git tag.
-version = "1.1.0"
+version = "1.3.0"
 edition = "2018"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
-documentation = "https://docs.rs/tokio-macros/1.1.0/tokio_macros"
+documentation = "https://docs.rs/tokio-macros/1.3.0/tokio_macros"
 description = """
 Tokio's proc macros.
 """

tokio-macros/src/entry.rs

@@ -201,12 +201,15 @@ fn parse_knobs(
     for arg in args {
         match arg {
             syn::NestedMeta::Meta(syn::Meta::NameValue(namevalue)) => {
-                let ident = namevalue.path.get_ident();
-                if ident.is_none() {
-                    let msg = "Must have specified ident";
-                    return Err(syn::Error::new_spanned(namevalue, msg));
-                }
-                match ident.unwrap().to_string().to_lowercase().as_str() {
+                let ident = namevalue
+                    .path
+                    .get_ident()
+                    .ok_or_else(|| {
+                        syn::Error::new_spanned(&namevalue, "Must have specified ident")
+                    })?
+                    .to_string()
+                    .to_lowercase();
+                match ident.as_str() {
                     "worker_threads" => {
                         config.set_worker_threads(
                             namevalue.lit.clone(),
@@ -239,12 +242,11 @@ fn parse_knobs(
                 }
             }
             syn::NestedMeta::Meta(syn::Meta::Path(path)) => {
-                let ident = path.get_ident();
-                if ident.is_none() {
-                    let msg = "Must have specified ident";
-                    return Err(syn::Error::new_spanned(path, msg));
-                }
-                let name = ident.unwrap().to_string().to_lowercase();
+                let name = path
+                    .get_ident()
+                    .ok_or_else(|| syn::Error::new_spanned(&path, "Must have specified ident"))?
+                    .to_string()
+                    .to_lowercase();
                 let msg = match name.as_str() {
                     "threaded_scheduler" | "multi_thread" => {
                         format!(
@@ -323,14 +325,16 @@ fn parse_knobs(
     let brace_token = input.block.brace_token;
     input.block = syn::parse2(quote_spanned! {last_stmt_end_span=>
         {
+            let body = async #body;
+            #[allow(clippy::expect_used)]
             #rt
                 .enable_all()
                 .build()
-                .unwrap()
-                .block_on(async #body)
+                .expect("Failed building the Runtime")
+                .block_on(body)
         }
     })
-    .unwrap();
+    .expect("Parsing failure");
     input.block.brace_token = brace_token;
 
     let result = quote! {

tokio-macros/src/lib.rs

@@ -5,7 +5,7 @@
     rust_2018_idioms,
     unreachable_pub
 )]
-#![cfg_attr(docsrs, deny(broken_intra_doc_links))]
+#![cfg_attr(docsrs, deny(rustdoc::broken_intra_doc_links))]
 #![doc(test(
     no_crate_inject,
     attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))

tokio-stream/CHANGELOG.md

@@ -1,3 +1,26 @@
+# 0.1.7 (July 7, 2021)
+
+### Fixed
+
+- sync: fix watch wrapper ([#3914])
+- time: fix `Timeout::size_hint` ([#3902])
+
+[#3902]: https://github.com/tokio-rs/tokio/pull/3902
+[#3914]: https://github.com/tokio-rs/tokio/pull/3914
+
+# 0.1.6 (May 14, 2021)
+
+### Added
+
+- stream: implement `Error` and `Display` for `BroadcastStreamRecvError` ([#3745])
+
+### Fixed
+
+- stream: avoid yielding in `AllFuture` and `AnyFuture` ([#3625])
+
+[#3745]: https://github.com/tokio-rs/tokio/pull/3745
+[#3625]: https://github.com/tokio-rs/tokio/pull/3625
+
 # 0.1.5 (March 20, 2021)
 
 ### Fixed

tokio-stream/Cargo.toml

@@ -6,13 +6,13 @@ name = "tokio-stream"
 #   - Cargo.toml
 # - Update CHANGELOG.md.
 # - Create "tokio-stream-0.1.x" git tag.
-version = "0.1.5"
+version = "0.1.7"
 edition = "2018"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
-documentation = "https://docs.rs/tokio-stream/0.1.5/tokio_stream"
+documentation = "https://docs.rs/tokio-stream/0.1.7/tokio_stream"
 description = """
 Utilities to work with `Stream` and `tokio`.
 """
@@ -30,7 +30,7 @@ signal = ["tokio/signal"]
 [dependencies]
 futures-core = { version = "0.3.0" }
 pin-project-lite = "0.2.0"
-tokio = { version = "1.2.0", path = "../tokio", features = ["sync"] }
+tokio = { version = "1.8.0", path = "../tokio", features = ["sync"] }
 tokio-util = { version = "0.6.3", path = "../tokio-util", optional = true }
 
 [dev-dependencies]
@@ -44,3 +44,8 @@ proptest = "1"
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
+# Issue #3770
+#
+# This should allow `docsrs` to be read across projects, so that `tokio-stream`
+# can pick up stubbed types exported by `tokio`.
+rustc-args = ["--cfg", "docsrs"]

tokio-stream/src/lib.rs

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

tokio-stream/src/stream_ext.rs

@@ -515,7 +515,7 @@ pub trait StreamExt: Stream {
     /// Skip elements from the underlying stream while the provided predicate
     /// resolves to `true`.
     ///
-    /// This function, like [`Iterator::skip_while`], will ignore elemets from the
+    /// This function, like [`Iterator::skip_while`], will ignore elements from the
     /// stream until the predicate `f` resolves to `false`. Once one element
     /// returns false, the rest of the elements will be yielded.
     ///

tokio-stream/src/stream_ext/collect.rs

@@ -113,7 +113,7 @@ impl<T: AsRef<str>> sealed::FromStreamPriv<T> for String {
     }
 
     fn finalize(_: sealed::Internal, collection: &mut String) -> String {
-        mem::replace(collection, String::new())
+        mem::take(collection)
     }
 }
 
@@ -132,7 +132,7 @@ impl<T> sealed::FromStreamPriv<T> for Vec<T> {
     }
 
     fn finalize(_: sealed::Internal, collection: &mut Vec<T>) -> Vec<T> {
-        mem::replace(collection, vec![])
+        mem::take(collection)
     }
 }
 

tokio-stream/src/stream_ext/timeout.rs

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

tokio-stream/src/stream_map.rs

@@ -364,11 +364,11 @@ impl<K, V> StreamMap<K, V> {
     /// # Examples
     ///
     /// ```
-    /// use std::collections::HashMap;
+    /// use tokio_stream::{StreamMap, pending};
     ///
-    /// let mut a = HashMap::new();
+    /// let mut a = StreamMap::new();
     /// assert!(a.is_empty());
-    /// a.insert(1, "a");
+    /// a.insert(1, pending::<i32>());
     /// assert!(!a.is_empty());
     /// ```
     pub fn is_empty(&self) -> bool {

tokio-stream/src/wrappers.rs

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

tokio-stream/src/wrappers/watch.rs

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

tokio-stream/tests/async_send_sync.rs

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

tokio-stream/tests/stream_chain.rs

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

tokio-stream/tests/stream_merge.rs

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

tokio-stream/tests/watch.rs

@@ -0,0 +1,27 @@
+use tokio::sync::watch;
+use tokio_stream::wrappers::WatchStream;
+use tokio_stream::StreamExt;
+
+#[tokio::test]
+async fn message_not_twice() {
+    let (tx, rx) = watch::channel("hello");
+
+    let mut counter = 0;
+    let mut stream = WatchStream::new(rx).map(move |payload| {
+        println!("{}", payload);
+        if payload == "goodbye" {
+            counter += 1;
+        }
+        if counter >= 2 {
+            panic!("too many goodbyes");
+        }
+    });
+
+    let task = tokio::spawn(async move { while stream.next().await.is_some() {} });
+
+    // Send goodbye just once
+    tx.send("goodbye").unwrap();
+
+    drop(tx);
+    task.await.unwrap();
+}

tokio-test/CHANGELOG.md

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

tokio-test/Cargo.toml

@@ -6,13 +6,13 @@ name = "tokio-test"
 #   - Cargo.toml
 # - Update CHANGELOG.md.
 # - Create "tokio-test-0.4.x" git tag.
-version = "0.4.1"
+version = "0.4.2"
 edition = "2018"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
-documentation = "https://docs.rs/tokio-test/0.4.1/tokio_test"
+documentation = "https://docs.rs/tokio-test/0.4.2/tokio_test"
 description = """
 Testing utilities for Tokio- and futures-based code
 """

tokio-test/src/lib.rs

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

tokio-test/src/task.rs

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

tokio-util/CHANGELOG.md

@@ -1,3 +1,13 @@
+# 0.6.7 (May 14, 2021)
+
+### Added
+
+- udp: make `UdpFramed` take `Borrow<UdpSocket>` ([#3451])
+- compat: implement `AsRawFd`/`AsRawHandle` for `Compat<T>` ([#3765])
+
+[#3451]: https://github.com/tokio-rs/tokio/pull/3451
+[#3765]: https://github.com/tokio-rs/tokio/pull/3765
+
 # 0.6.6 (April 12, 2021)
 
 ### Added

tokio-util/Cargo.toml

@@ -6,13 +6,13 @@ name = "tokio-util"
 #   - Cargo.toml
 # - Update CHANGELOG.md.
 # - Create "tokio-util-0.6.x" git tag.
-version = "0.6.6"
+version = "0.6.7"
 edition = "2018"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
-documentation = "https://docs.rs/tokio-util/0.6.6/tokio_util"
+documentation = "https://docs.rs/tokio-util/0.6.7/tokio_util"
 description = """
 Additional utilities for working with Tokio.
 """

tokio-util/src/codec/any_delimiter_codec.rs

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

tokio-util/src/codec/decoder.rs

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

tokio-util/src/codec/framed_impl.rs

@@ -124,7 +124,7 @@ where
         // to a combination of the `is_readable` and `eof` flags. States persist across
         // loop entries and most state transitions occur with a return.
         //
-        // The intitial state is `reading`.
+        // The initial state is `reading`.
         //
         // | state   | eof   | is_readable |
         // |---------|-------|-------------|
@@ -155,10 +155,10 @@ where
             // Both signal that there is no such data by returning `None`.
             //
             // If `decode` couldn't read a frame and the upstream source has returned eof,
-            // `decode_eof` will attemp to decode the remaining bytes as closing frames.
+            // `decode_eof` will attempt to decode the remaining bytes as closing frames.
             //
             // If the underlying AsyncRead is resumable, we may continue after an EOF,
-            // but must finish emmiting all of it's associated `decode_eof` frames.
+            // but must finish emitting all of it's associated `decode_eof` frames.
             // Furthermore, we don't want to emit any `decode_eof` frames on retried
             // reads after an EOF unless we've actually read more data.
             if state.is_readable {

tokio-util/src/codec/length_delimited.rs

@@ -486,7 +486,7 @@ impl LengthDelimitedCodec {
             // Skip the required bytes
             src.advance(self.builder.length_field_offset);
 
-            // match endianess
+            // match endianness
             let n = if self.builder.length_field_is_big_endian {
                 src.get_uint(field_len)
             } else {

tokio-util/src/codec/lines_codec.rs

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

tokio-util/src/either.rs

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

tokio-util/src/lib.rs

@@ -5,7 +5,7 @@
     rust_2018_idioms,
     unreachable_pub
 )]
-#![cfg_attr(docsrs, deny(broken_intra_doc_links))]
+#![cfg_attr(docsrs, deny(rustdoc::broken_intra_doc_links))]
 #![doc(test(
     no_crate_inject,
     attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))

tokio-util/src/sync/cancellation_token.rs

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

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

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

tokio-util/src/sync/intrusive_double_linked_list.rs

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

tokio-util/src/sync/mod.rs

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

tokio-util/src/time/mod.rs

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

tokio-util/src/udp/frame.rs

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

tokio-util/tests/poll_semaphore.rs

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

tokio-util/tests/sync_cancellation_token.rs

@@ -11,7 +11,7 @@ use futures_test::task::new_count_waker;
 fn cancel_token() {
     let (waker, wake_counter) = new_count_waker();
     let token = CancellationToken::new();
-    assert_eq!(false, token.is_cancelled());
+    assert!(!token.is_cancelled());
 
     let wait_fut = token.cancelled();
     pin!(wait_fut);
@@ -27,7 +27,7 @@ fn cancel_token() {
 
     token.cancel();
     assert_eq!(wake_counter, 1);
-    assert_eq!(true, token.is_cancelled());
+    assert!(token.is_cancelled());
 
     assert_eq!(
         Poll::Ready(()),
@@ -64,8 +64,8 @@ fn cancel_child_token_through_parent() {
 
     token.cancel();
     assert_eq!(wake_counter, 2);
-    assert_eq!(true, token.is_cancelled());
-    assert_eq!(true, child_token.is_cancelled());
+    assert!(token.is_cancelled());
+    assert!(child_token.is_cancelled());
 
     assert_eq!(
         Poll::Ready(()),
@@ -101,8 +101,8 @@ fn cancel_child_token_without_parent() {
 
     child_token_1.cancel();
     assert_eq!(wake_counter, 1);
-    assert_eq!(false, token.is_cancelled());
-    assert_eq!(true, child_token_1.is_cancelled());
+    assert!(!token.is_cancelled());
+    assert!(child_token_1.is_cancelled());
 
     assert_eq!(
         Poll::Ready(()),
@@ -128,8 +128,8 @@ fn cancel_child_token_without_parent() {
 
     token.cancel();
     assert_eq!(wake_counter, 3);
-    assert_eq!(true, token.is_cancelled());
-    assert_eq!(true, child_token_2.is_cancelled());
+    assert!(token.is_cancelled());
+    assert!(child_token_2.is_cancelled());
 
     assert_eq!(
         Poll::Ready(()),

tokio/CHANGELOG.md

@@ -1,3 +1,223 @@
+# 1.10.1 (August 24, 2021)
+
+### Fixed
+
+ - runtime: fix leak in UnownedTask ([#4063])
+
+[#4063]: https://github.com/tokio-rs/tokio/pull/4063
+
+# 1.10.0 (August 12, 2021)
+
+### Added
+
+ - io: add `(read|write)_f(32|64)[_le]` methods ([#4022])
+ - io: add `fill_buf` and `consume` to `AsyncBufReadExt` ([#3991])
+ - process: add `Child::raw_handle()` on windows ([#3998])
+
+### Fixed
+
+ - doc: fix non-doc builds with `--cfg docsrs` ([#4020])
+ - io: flush eagerly in `io::copy` ([#4001])
+ - runtime: a debug assert was sometimes triggered during shutdown ([#4005])
+ - sync: use `spin_loop_hint` instead of `yield_now` in mpsc ([#4037])
+ - tokio: the test-util feature depends on rt, sync, and time ([#4036])
+
+### Changes
+
+ - runtime: reorganize parts of the runtime ([#3979], [#4005])
+ - signal: make windows docs for signal module show up on unix builds ([#3770])
+ - task: quickly send task to heap on debug mode ([#4009])
+
+### Documented
+
+ - io: document cancellation safety of `AsyncBufReadExt` ([#3997])
+ - sync: document when `watch::send` fails ([#4021])
+
+[#3770]: https://github.com/tokio-rs/tokio/pull/3770
+[#3979]: https://github.com/tokio-rs/tokio/pull/3979
+[#3991]: https://github.com/tokio-rs/tokio/pull/3991
+[#3997]: https://github.com/tokio-rs/tokio/pull/3997
+[#3998]: https://github.com/tokio-rs/tokio/pull/3998
+[#4001]: https://github.com/tokio-rs/tokio/pull/4001
+[#4005]: https://github.com/tokio-rs/tokio/pull/4005
+[#4009]: https://github.com/tokio-rs/tokio/pull/4009
+[#4020]: https://github.com/tokio-rs/tokio/pull/4020
+[#4021]: https://github.com/tokio-rs/tokio/pull/4021
+[#4022]: https://github.com/tokio-rs/tokio/pull/4022
+[#4036]: https://github.com/tokio-rs/tokio/pull/4036
+[#4037]: https://github.com/tokio-rs/tokio/pull/4037
+
+# 1.9.0 (July 22, 2021)
+
+### Added
+
+ - net: allow customized I/O operations for `TcpStream` ([#3888])
+ - sync: add getter for the mutex from a guard ([#3928])
+ - task: expose nameable future for `TaskLocal::scope` ([#3273])
+
+### Fixed
+
+ - Fix leak if output of future panics on drop ([#3967])
+ - Fix leak in `LocalSet` ([#3978])
+
+### Changes
+
+ - runtime: reorganize parts of the runtime ([#3909], [#3939], [#3950], [#3955], [#3980])
+ - sync: clean up `OnceCell` ([#3945])
+ - task: remove mutex in `JoinError` ([#3959])
+
+[#3273]: https://github.com/tokio-rs/tokio/pull/3273
+[#3888]: https://github.com/tokio-rs/tokio/pull/3888
+[#3909]: https://github.com/tokio-rs/tokio/pull/3909
+[#3928]: https://github.com/tokio-rs/tokio/pull/3928
+[#3934]: https://github.com/tokio-rs/tokio/pull/3934
+[#3939]: https://github.com/tokio-rs/tokio/pull/3939
+[#3945]: https://github.com/tokio-rs/tokio/pull/3945
+[#3950]: https://github.com/tokio-rs/tokio/pull/3950
+[#3955]: https://github.com/tokio-rs/tokio/pull/3955
+[#3959]: https://github.com/tokio-rs/tokio/pull/3959
+[#3967]: https://github.com/tokio-rs/tokio/pull/3967
+[#3978]: https://github.com/tokio-rs/tokio/pull/3978
+[#3980]: https://github.com/tokio-rs/tokio/pull/3980
+
+# 1.8.3 (July 26, 2021)
+
+This release backports two fixes from 1.9.0
+
+### Fixed
+
+ - Fix leak if output of future panics on drop ([#3967])
+ - Fix leak in `LocalSet` ([#3978])
+
+[#3967]: https://github.com/tokio-rs/tokio/pull/3967
+[#3978]: https://github.com/tokio-rs/tokio/pull/3978
+
+# 1.8.2 (July 19, 2021)
+
+Fixes a missed edge case from 1.8.1.
+
+### Fixed
+
+- runtime: drop canceled future on next poll (#3965)
+
+# 1.8.1 (July 6, 2021)
+
+Forward ports 1.5.1 fixes.
+
+### Fixed
+
+- runtime: remotely abort tasks on `JoinHandle::abort` ([#3934])
+
+[#3934]: https://github.com/tokio-rs/tokio/pull/3934
+
+# 1.8.0 (July 2, 2021)
+
+### Added
+
+- io: add `get_{ref,mut}` methods to `AsyncFdReadyGuard` and `AsyncFdReadyMutGuard` ([#3807])
+- io: efficient implementation of vectored writes for `BufWriter` ([#3163])
+- net: add ready/try methods to `NamedPipe{Client,Server}` ([#3866], [#3899])
+- sync: add `watch::Receiver::borrow_and_update` ([#3813])
+- sync: implement `From<T>` for `OnceCell<T>` ([#3877])
+- time: allow users to specify Interval behaviour when delayed ([#3721])
+
+### Added (unstable)
+
+- rt: add `tokio::task::Builder` ([#3881])
+
+### Fixed
+
+- net: handle HUP event with `UnixStream` ([#3898])
+
+### Documented
+
+- doc: document cancellation safety ([#3900])
+- time: add wait alias to sleep ([#3897])
+- time: document auto-advancing behaviour of runtime ([#3763])
+
+[#3163]: https://github.com/tokio-rs/tokio/pull/3163
+[#3721]: https://github.com/tokio-rs/tokio/pull/3721
+[#3763]: https://github.com/tokio-rs/tokio/pull/3763
+[#3807]: https://github.com/tokio-rs/tokio/pull/3807
+[#3813]: https://github.com/tokio-rs/tokio/pull/3813
+[#3866]: https://github.com/tokio-rs/tokio/pull/3866
+[#3877]: https://github.com/tokio-rs/tokio/pull/3877
+[#3881]: https://github.com/tokio-rs/tokio/pull/3881
+[#3897]: https://github.com/tokio-rs/tokio/pull/3897
+[#3898]: https://github.com/tokio-rs/tokio/pull/3898
+[#3899]: https://github.com/tokio-rs/tokio/pull/3899
+[#3900]: https://github.com/tokio-rs/tokio/pull/3900
+
+# 1.7.2 (July 6, 2021)
+
+Forward ports 1.5.1 fixes.
+
+### Fixed
+
+- runtime: remotely abort tasks on `JoinHandle::abort` ([#3934])
+
+[#3934]: https://github.com/tokio-rs/tokio/pull/3934
+
+# 1.7.1 (June 18, 2021)
+
+### Fixed
+
+- runtime: fix early task shutdown during runtime shutdown ([#3870])
+
+[#3870]: https://github.com/tokio-rs/tokio/pull/3870
+
+# 1.7.0 (June 15, 2021)
+
+### Added
+
+- net: add named pipes on windows ([#3760])
+- net: add `TcpSocket` from `std::net::TcpStream` conversion ([#3838])
+- sync: add `receiver_count` to `watch::Sender` ([#3729])
+- sync: export `sync::notify::Notified` future publicly ([#3840])
+- tracing: instrument task wakers ([#3836])
+
+### Fixed
+
+- macros: suppress `clippy::default_numeric_fallback` lint in generated code ([#3831])
+- runtime: immediately drop new tasks when runtime is shut down ([#3752])
+- sync: deprecate unused `mpsc::RecvError` type ([#3833])
+
+### Documented
+
+- io: clarify EOF condition for `AsyncReadExt::read_buf` ([#3850])
+- io: clarify limits on return values of `AsyncWrite::poll_write` ([#3820])
+- sync: add examples to Semaphore ([#3808])
+
+[#3729]: https://github.com/tokio-rs/tokio/pull/3729
+[#3752]: https://github.com/tokio-rs/tokio/pull/3752
+[#3760]: https://github.com/tokio-rs/tokio/pull/3760
+[#3808]: https://github.com/tokio-rs/tokio/pull/3808
+[#3820]: https://github.com/tokio-rs/tokio/pull/3820
+[#3831]: https://github.com/tokio-rs/tokio/pull/3831
+[#3833]: https://github.com/tokio-rs/tokio/pull/3833
+[#3836]: https://github.com/tokio-rs/tokio/pull/3836
+[#3838]: https://github.com/tokio-rs/tokio/pull/3838
+[#3840]: https://github.com/tokio-rs/tokio/pull/3840
+[#3850]: https://github.com/tokio-rs/tokio/pull/3850
+
+# 1.6.3 (July 6, 2021)
+
+Forward ports 1.5.1 fixes.
+
+### Fixed
+
+- runtime: remotely abort tasks on `JoinHandle::abort` ([#3934])
+
+[#3934]: https://github.com/tokio-rs/tokio/pull/3934
+
+# 1.6.2 (June 14, 2021)
+
+### Fixes
+
+- test: sub-ms `time:advance` regression introduced in 1.6 ([#3852])
+
+[#3852]: https://github.com/tokio-rs/tokio/pull/3852
+
 # 1.6.1 (May 28, 2021)
 
 This release reverts [#3518] because it doesn't work on some kernels due to
@@ -52,6 +272,14 @@ a kernel bug. ([#3803])
 [#3775]: https://github.com/tokio-rs/tokio/pull/3775
 [#3780]: https://github.com/tokio-rs/tokio/pull/3780
 
+# 1.5.1 (July 6, 2021)
+
+### Fixed
+
+- runtime: remotely abort tasks on `JoinHandle::abort` ([#3934])
+
+[#3934]: https://github.com/tokio-rs/tokio/pull/3934
+
 # 1.5.0 (April 12, 2021)
 
 ### Added

tokio/Cargo.toml

@@ -7,12 +7,12 @@ name = "tokio"
 #   - README.md
 # - Update CHANGELOG.md.
 # - Create "v1.0.x" git tag.
-version = "1.6.1"
+version = "1.10.1"
 edition = "2018"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 readme = "README.md"
-documentation = "https://docs.rs/tokio/1.6.0/tokio/"
+documentation = "https://docs.rs/tokio/1.10.0/tokio/"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
 description = """
@@ -54,6 +54,7 @@ net = [
   "mio/tcp",
   "mio/udp",
   "mio/uds",
+  "winapi/namedpipeapi",
 ]
 process = [
   "bytes",
@@ -81,7 +82,7 @@ signal = [
   "winapi/consoleapi",
 ]
 sync = []
-test-util = []
+test-util = ["rt", "sync", "time"]
 time = []
 
 [dependencies]
@@ -108,21 +109,26 @@ signal-hook-registry = { version = "1.1.1", optional = true }
 
 [target.'cfg(unix)'.dev-dependencies]
 libc = { version = "0.2.42" }
-nix = { version = "0.19.0" }
+nix = { version = "0.22.0" }
 
 [target.'cfg(windows)'.dependencies.winapi]
 version = "0.3.8"
 default-features = false
 optional = true
 
+[target.'cfg(windows)'.dev-dependencies.ntapi]
+version = "0.3.6"
+
 [dev-dependencies]
 tokio-test = { version = "0.4.0", path = "../tokio-test" }
 tokio-stream = { version = "0.1", path = "../tokio-stream" }
 futures = { version = "0.3.0", features = ["async-await"] }
+mockall = "0.10.2"
 proptest = "1"
 rand = "0.8.0"
 tempfile = "3.1.0"
 async-stream = "0.3"
+socket2 = "0.4"
 
 [target.'cfg(loom)'.dev-dependencies]
 loom = { version = "0.5", features = ["futures", "checkpoint"] }

tokio/README.md

@@ -50,7 +50,15 @@ an asynchronous application.
 
 ## Example
 
-A basic TCP echo server with Tokio:
+A basic TCP echo server with Tokio.
+
+Make sure you activated the full features of the tokio crate on Cargo.toml:
+
+```toml
+[dependencies]
+tokio = { version = "1.10.1", features = ["full"] }
+```
+Then, on your main.rs:
 
 ```rust,no_run
 use tokio::net::TcpListener;
@@ -58,7 +66,7 @@ use tokio::io::{AsyncReadExt, AsyncWriteExt};
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let mut listener = TcpListener::bind("127.0.0.1:8080").await?;
+    let listener = TcpListener::bind("127.0.0.1:8080").await?;
 
     loop {
         let (mut socket, _) = listener.accept().await?;
@@ -132,7 +140,7 @@ several other libraries, including:
 
 * [`tower`]: A library of modular and reusable components for building robust networking clients and servers.
 
-* [`tracing`]: A framework for application-level tracing and async-aware diagnostics.
+* [`tracing`] (formerly `tokio-trace`): A framework for application-level tracing and async-aware diagnostics.
 
 * [`rdbc`]: A Rust database connectivity library for MySQL, Postgres and SQLite.
 
@@ -155,9 +163,35 @@ several other libraries, including:
 
 ## Supported Rust Versions
 
-Tokio is built against the latest stable release. The minimum supported version is 1.45.
-The current Tokio version is not guaranteed to build on Rust versions earlier than the
-minimum supported version.
+Tokio is built against the latest stable release. The minimum supported version
+is 1.45.  The current Tokio version is not guaranteed to build on Rust versions
+earlier than the minimum supported version.
+
+## Release schedule
+
+Tokio doesn't follow a fixed release schedule, but we typically make one to two
+new minor releases each month. We make patch releases for bugfixes as necessary.
+
+## Bug patching policy
+
+For the purposes of making patch releases with bugfixes, we have designated
+certain minor releases as LTS (long term support) releases. Whenever a bug
+warrants a patch release with a fix for the bug, it will be backported and
+released as a new patch release for each LTS minor version. Our current LTS
+releases are:
+
+ * `1.8.x` - LTS release until February 2022.
+
+Each LTS release will continue to receive backported fixes for at least half a
+year. If you wish to use a fixed minor release in your project, we recommend
+that you use an LTS release.
+
+To use a fixed minor version, you can specify the version with a tilde. For
+example, to specify that you wish to use the newest `1.8.x` patch release, you
+can use the following dependency specification:
+```text
+tokio = { version = "~1.8", features = [...] }
+```
 
 ## License
 

tokio/docs/reactor-refactor.md

@@ -228,7 +228,7 @@ It is only possible to implement `AsyncRead` and `AsyncWrite` for resource types
 themselves and not for `&Resource`. Implementing the traits for `&Resource`
 would permit concurrent operations to the resource. Because only a single waker
 is stored per direction, any concurrent usage would result in deadlocks. An
-alterate implementation would call for a `Vec<Waker>` but this would result in
+alternate implementation would call for a `Vec<Waker>` but this would result in
 memory leaks.
 
 ## Enabling reads and writes for `&TcpStream`
@@ -268,9 +268,9 @@ select! {
 }
 ```
 
-It is also possible to sotre a `TcpStream` in an `Arc`.
+It is also possible to store a `TcpStream` in an `Arc`.
 
 ```rust
 let arc_stream = Arc::new(my_tcp_stream);
 let n = arc_stream.by_ref().read(buf).await?;
-```
+```

tokio/src/doc/mod.rs

@@ -0,0 +1,23 @@
+//! Types which are documented locally in the Tokio crate, but does not actually
+//! live here.
+//!
+//! **Note** this module is only visible on docs.rs, you cannot use it directly
+//! in your own code.
+
+/// The name of a type which is not defined here.
+///
+/// This is typically used as an alias for another type, like so:
+///
+/// ```rust,ignore
+/// /// See [some::other::location](https://example.com).
+/// type DEFINED_ELSEWHERE = crate::doc::NotDefinedHere;
+/// ```
+///
+/// This type is uninhabitable like the [`never` type] to ensure that no one
+/// will ever accidentally use it.
+///
+/// [`never` type]: https://doc.rust-lang.org/std/primitive.never.html
+pub enum NotDefinedHere {}
+
+pub mod os;
+pub mod winapi;

tokio/src/doc/os.rs

@@ -0,0 +1,26 @@
+//! See [std::os](https://doc.rust-lang.org/std/os/index.html).
+
+/// Platform-specific extensions to `std` for Windows.
+///
+/// See [std::os::windows](https://doc.rust-lang.org/std/os/windows/index.html).
+pub mod windows {
+    /// Windows-specific extensions to general I/O primitives.
+    ///
+    /// See [std::os::windows::io](https://doc.rust-lang.org/std/os/windows/io/index.html).
+    pub mod io {
+        /// See [std::os::windows::io::RawHandle](https://doc.rust-lang.org/std/os/windows/io/type.RawHandle.html)
+        pub type RawHandle = crate::doc::NotDefinedHere;
+
+        /// See [std::os::windows::io::AsRawHandle](https://doc.rust-lang.org/std/os/windows/io/trait.AsRawHandle.html)
+        pub trait AsRawHandle {
+            /// See [std::os::windows::io::FromRawHandle::from_raw_handle](https://doc.rust-lang.org/std/os/windows/io/trait.AsRawHandle.html#tymethod.as_raw_handle)
+            fn as_raw_handle(&self) -> RawHandle;
+        }
+
+        /// See [std::os::windows::io::FromRawHandle](https://doc.rust-lang.org/std/os/windows/io/trait.FromRawHandle.html)
+        pub trait FromRawHandle {
+            /// See [std::os::windows::io::FromRawHandle::from_raw_handle](https://doc.rust-lang.org/std/os/windows/io/trait.FromRawHandle.html#tymethod.from_raw_handle)
+            unsafe fn from_raw_handle(handle: RawHandle) -> Self;
+        }
+    }
+}

tokio/src/doc/winapi.rs

@@ -0,0 +1,66 @@
+//! See [winapi].
+//!
+//! [winapi]: https://docs.rs/winapi
+
+/// See [winapi::shared](https://docs.rs/winapi/*/winapi/shared/index.html).
+pub mod shared {
+    /// See [winapi::shared::winerror](https://docs.rs/winapi/*/winapi/shared/winerror/index.html).
+    #[allow(non_camel_case_types)]
+    pub mod winerror {
+        /// See [winapi::shared::winerror::ERROR_ACCESS_DENIED][winapi]
+        ///
+        /// [winapi]: https://docs.rs/winapi/*/winapi/shared/winerror/constant.ERROR_ACCESS_DENIED.html
+        pub type ERROR_ACCESS_DENIED = crate::doc::NotDefinedHere;
+
+        /// See [winapi::shared::winerror::ERROR_PIPE_BUSY][winapi]
+        ///
+        /// [winapi]: https://docs.rs/winapi/*/winapi/shared/winerror/constant.ERROR_PIPE_BUSY.html
+        pub type ERROR_PIPE_BUSY = crate::doc::NotDefinedHere;
+
+        /// See [winapi::shared::winerror::ERROR_MORE_DATA][winapi]
+        ///
+        /// [winapi]: https://docs.rs/winapi/*/winapi/shared/winerror/constant.ERROR_MORE_DATA.html
+        pub type ERROR_MORE_DATA = crate::doc::NotDefinedHere;
+    }
+}
+
+/// See [winapi::um](https://docs.rs/winapi/*/winapi/um/index.html).
+pub mod um {
+    /// See [winapi::um::winbase](https://docs.rs/winapi/*/winapi/um/winbase/index.html).
+    #[allow(non_camel_case_types)]
+    pub mod winbase {
+        /// See [winapi::um::winbase::PIPE_TYPE_MESSAGE][winapi]
+        ///
+        /// [winapi]: https://docs.rs/winapi/*/winapi/um/winbase/constant.PIPE_TYPE_MESSAGE.html
+        pub type PIPE_TYPE_MESSAGE = crate::doc::NotDefinedHere;
+
+        /// See [winapi::um::winbase::PIPE_TYPE_BYTE][winapi]
+        ///
+        /// [winapi]: https://docs.rs/winapi/*/winapi/um/winbase/constant.PIPE_TYPE_BYTE.html
+        pub type PIPE_TYPE_BYTE = crate::doc::NotDefinedHere;
+
+        /// See [winapi::um::winbase::PIPE_CLIENT_END][winapi]
+        ///
+        /// [winapi]: https://docs.rs/winapi/*/winapi/um/winbase/constant.PIPE_CLIENT_END.html
+        pub type PIPE_CLIENT_END = crate::doc::NotDefinedHere;
+
+        /// See [winapi::um::winbase::PIPE_SERVER_END][winapi]
+        ///
+        /// [winapi]: https://docs.rs/winapi/*/winapi/um/winbase/constant.PIPE_SERVER_END.html
+        pub type PIPE_SERVER_END = crate::doc::NotDefinedHere;
+
+        /// See [winapi::um::winbase::SECURITY_IDENTIFICATION][winapi]
+        ///
+        /// [winapi]: https://docs.rs/winapi/*/winapi/um/winbase/constant.SECURITY_IDENTIFICATION.html
+        pub type SECURITY_IDENTIFICATION = crate::doc::NotDefinedHere;
+    }
+
+    /// See [winapi::um::minwinbase](https://docs.rs/winapi/*/winapi/um/minwinbase/index.html).
+    #[allow(non_camel_case_types)]
+    pub mod minwinbase {
+        /// See [winapi::um::minwinbase::SECURITY_ATTRIBUTES][winapi]
+        ///
+        /// [winapi]: https://docs.rs/winapi/*/winapi/um/minwinbase/constant.SECURITY_ATTRIBUTES.html
+        pub type SECURITY_ATTRIBUTES = crate::doc::NotDefinedHere;
+    }
+}

tokio/src/fs/file.rs

@@ -3,7 +3,7 @@
 //! [`File`]: File
 
 use self::State::*;
-use crate::fs::{asyncify, sys};
+use crate::fs::asyncify;
 use crate::io::blocking::Buf;
 use crate::io::{AsyncRead, AsyncSeek, AsyncWrite, ReadBuf};
 use crate::sync::Mutex;
@@ -19,6 +19,19 @@ use std::task::Context;
 use std::task::Poll;
 use std::task::Poll::*;
 
+#[cfg(test)]
+use super::mocks::spawn_blocking;
+#[cfg(test)]
+use super::mocks::JoinHandle;
+#[cfg(test)]
+use super::mocks::MockFile as StdFile;
+#[cfg(not(test))]
+use crate::blocking::spawn_blocking;
+#[cfg(not(test))]
+use crate::blocking::JoinHandle;
+#[cfg(not(test))]
+use std::fs::File as StdFile;
+
 /// A reference to an open file on the filesystem.
 ///
 /// This is a specialized version of [`std::fs::File`][std] for usage from the
@@ -78,7 +91,7 @@ use std::task::Poll::*;
 /// # }
 /// ```
 pub struct File {
-    std: Arc<sys::File>,
+    std: Arc<StdFile>,
     inner: Mutex<Inner>,
 }
 
@@ -96,7 +109,7 @@ struct Inner {
 #[derive(Debug)]
 enum State {
     Idle(Option<Buf>),
-    Busy(sys::Blocking<(Operation, Buf)>),
+    Busy(JoinHandle<(Operation, Buf)>),
 }
 
 #[derive(Debug)]
@@ -142,7 +155,7 @@ impl File {
     /// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
     pub async fn open(path: impl AsRef<Path>) -> io::Result<File> {
         let path = path.as_ref().to_owned();
-        let std = asyncify(|| sys::File::open(path)).await?;
+        let std = asyncify(|| StdFile::open(path)).await?;
 
         Ok(File::from_std(std))
     }
@@ -182,7 +195,7 @@ impl File {
     /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
     pub async fn create(path: impl AsRef<Path>) -> io::Result<File> {
         let path = path.as_ref().to_owned();
-        let std_file = asyncify(move || sys::File::create(path)).await?;
+        let std_file = asyncify(move || StdFile::create(path)).await?;
         Ok(File::from_std(std_file))
     }
 
@@ -199,7 +212,7 @@ impl File {
     /// let std_file = std::fs::File::open("foo.txt").unwrap();
     /// let file = tokio::fs::File::from_std(std_file);
     /// ```
-    pub fn from_std(std: sys::File) -> File {
+    pub fn from_std(std: StdFile) -> File {
         File {
             std: Arc::new(std),
             inner: Mutex::new(Inner {
@@ -323,7 +336,7 @@ impl File {
 
         let std = self.std.clone();
 
-        inner.state = Busy(sys::run(move || {
+        inner.state = Busy(spawn_blocking(move || {
             let res = if let Some(seek) = seek {
                 (&*std).seek(seek).and_then(|_| std.set_len(size))
             } else {
@@ -409,7 +422,7 @@ impl File {
     /// # Ok(())
     /// # }
     /// ```
-    pub async fn into_std(mut self) -> sys::File {
+    pub async fn into_std(mut self) -> StdFile {
         self.inner.get_mut().complete_inflight().await;
         Arc::try_unwrap(self.std).expect("Arc::try_unwrap failed")
     }
@@ -434,7 +447,7 @@ impl File {
     /// # Ok(())
     /// # }
     /// ```
-    pub fn try_into_std(mut self) -> Result<sys::File, Self> {
+    pub fn try_into_std(mut self) -> Result<StdFile, Self> {
         match Arc::try_unwrap(self.std) {
             Ok(file) => Ok(file),
             Err(std_file_arc) => {
@@ -502,7 +515,7 @@ impl AsyncRead for File {
                     buf.ensure_capacity_for(dst);
                     let std = me.std.clone();
 
-                    inner.state = Busy(sys::run(move || {
+                    inner.state = Busy(spawn_blocking(move || {
                         let res = buf.read_from(&mut &*std);
                         (Operation::Read(res), buf)
                     }));
@@ -569,7 +582,7 @@ impl AsyncSeek for File {
 
                     let std = me.std.clone();
 
-                    inner.state = Busy(sys::run(move || {
+                    inner.state = Busy(spawn_blocking(move || {
                         let res = (&*std).seek(pos);
                         (Operation::Seek(res), buf)
                     }));
@@ -636,7 +649,7 @@ impl AsyncWrite for File {
                     let n = buf.copy_from(src);
                     let std = me.std.clone();
 
-                    inner.state = Busy(sys::run(move || {
+                    inner.state = Busy(spawn_blocking(move || {
                         let res = if let Some(seek) = seek {
                             (&*std).seek(seek).and_then(|_| buf.write_to(&mut &*std))
                         } else {
@@ -685,8 +698,8 @@ impl AsyncWrite for File {
     }
 }
 
-impl From<sys::File> for File {
-    fn from(std: sys::File) -> Self {
+impl From<StdFile> for File {
+    fn from(std: StdFile) -> Self {
         Self::from_std(std)
     }
 }
@@ -709,7 +722,7 @@ impl std::os::unix::io::AsRawFd for File {
 #[cfg(unix)]
 impl std::os::unix::io::FromRawFd for File {
     unsafe fn from_raw_fd(fd: std::os::unix::io::RawFd) -> Self {
-        sys::File::from_raw_fd(fd).into()
+        StdFile::from_raw_fd(fd).into()
     }
 }
 
@@ -723,7 +736,7 @@ impl std::os::windows::io::AsRawHandle for File {
 #[cfg(windows)]
 impl std::os::windows::io::FromRawHandle for File {
     unsafe fn from_raw_handle(handle: std::os::windows::io::RawHandle) -> Self {
-        sys::File::from_raw_handle(handle).into()
+        StdFile::from_raw_handle(handle).into()
     }
 }
 
@@ -756,3 +769,6 @@ impl Inner {
         }
     }
 }
+
+#[cfg(test)]
+mod tests;

tokio/src/fs/file/tests.rs

@@ -1,80 +1,21 @@
-#![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
-
-macro_rules! ready {
-    ($e:expr $(,)?) => {
-        match $e {
-            std::task::Poll::Ready(t) => t,
-            std::task::Poll::Pending => return std::task::Poll::Pending,
-        }
-    };
-}
-
-#[macro_export]
-macro_rules! cfg_fs {
-    ($($item:item)*) => { $($item)* }
-}
-
-#[macro_export]
-macro_rules! cfg_io_std {
-    ($($item:item)*) => { $($item)* }
-}
-
-use futures::future;
-
-// Load source
-#[allow(warnings)]
-#[path = "../src/fs/file.rs"]
-mod file;
-use file::File;
-
-#[allow(warnings)]
-#[path = "../src/io/blocking.rs"]
-mod blocking;
-
-// Load mocked types
-mod support {
-    pub(crate) mod mock_file;
-    pub(crate) mod mock_pool;
-}
-pub(crate) use support::mock_pool as pool;
-
-// Place them where the source expects them
-pub(crate) mod io {
-    pub(crate) use tokio::io::*;
-
-    pub(crate) use crate::blocking;
-
-    pub(crate) mod sys {
-        pub(crate) use crate::support::mock_pool::{run, Blocking};
-    }
-}
-pub(crate) mod fs {
-    pub(crate) mod sys {
-        pub(crate) use crate::support::mock_file::File;
-        pub(crate) use crate::support::mock_pool::{run, Blocking};
-    }
-
-    pub(crate) use crate::support::mock_pool::asyncify;
-}
-pub(crate) mod sync {
-    pub(crate) use tokio::sync::Mutex;
-}
-use fs::sys;
-
-use tokio::io::{AsyncReadExt, AsyncSeekExt, AsyncWriteExt};
-use tokio_test::{assert_pending, assert_ready, assert_ready_err, assert_ready_ok, task};
-
-use std::io::SeekFrom;
+use super::*;
+use crate::{
+    fs::mocks::*,
+    io::{AsyncReadExt, AsyncSeekExt, AsyncWriteExt},
+};
+use mockall::{predicate::eq, Sequence};
+use tokio_test::{assert_pending, assert_ready_err, assert_ready_ok, task};
 
 const HELLO: &[u8] = b"hello world...";
 const FOO: &[u8] = b"foo bar baz...";
 
 #[test]
 fn open_read() {
-    let (mock, file) = sys::File::mock();
-    mock.read(HELLO);
-
+    let mut file = MockFile::default();
+    file.expect_inner_read().once().returning(|buf| {
+        buf[0..HELLO.len()].copy_from_slice(HELLO);
+        Ok(HELLO.len())
+    });
     let mut file = File::from_std(file);
 
     let mut buf = [0; 1024];
@@ -83,12 +24,10 @@ fn open_read() {
     assert_eq!(0, pool::len());
     assert_pending!(t.poll());
 
-    assert_eq!(1, mock.remaining());
     assert_eq!(1, pool::len());
 
     pool::run_one();
 
-    assert_eq!(0, mock.remaining());
     assert!(t.is_woken());
 
     let n = assert_ready_ok!(t.poll());
@@ -98,9 +37,11 @@ fn open_read() {
 
 #[test]
 fn read_twice_before_dispatch() {
-    let (mock, file) = sys::File::mock();
-    mock.read(HELLO);
-
+    let mut file = MockFile::default();
+    file.expect_inner_read().once().returning(|buf| {
+        buf[0..HELLO.len()].copy_from_slice(HELLO);
+        Ok(HELLO.len())
+    });
     let mut file = File::from_std(file);
 
     let mut buf = [0; 1024];
@@ -120,8 +61,11 @@ fn read_twice_before_dispatch() {
 
 #[test]
 fn read_with_smaller_buf() {
-    let (mock, file) = sys::File::mock();
-    mock.read(HELLO);
+    let mut file = MockFile::default();
+    file.expect_inner_read().once().returning(|buf| {
+        buf[0..HELLO.len()].copy_from_slice(HELLO);
+        Ok(HELLO.len())
+    });
 
     let mut file = File::from_std(file);
 
@@ -153,8 +97,22 @@ fn read_with_smaller_buf() {
 
 #[test]
 fn read_with_bigger_buf() {
-    let (mock, file) = sys::File::mock();
-    mock.read(&HELLO[..4]).read(&HELLO[4..]);
+    let mut seq = Sequence::new();
+    let mut file = MockFile::default();
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|buf| {
+            buf[0..4].copy_from_slice(&HELLO[..4]);
+            Ok(4)
+        });
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|buf| {
+            buf[0..HELLO.len() - 4].copy_from_slice(&HELLO[4..]);
+            Ok(HELLO.len() - 4)
+        });
 
     let mut file = File::from_std(file);
 
@@ -194,8 +152,19 @@ fn read_with_bigger_buf() {
 
 #[test]
 fn read_err_then_read_success() {
-    let (mock, file) = sys::File::mock();
-    mock.read_err().read(&HELLO);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|_| Err(io::ErrorKind::Other.into()));
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|buf| {
+            buf[0..HELLO.len()].copy_from_slice(HELLO);
+            Ok(HELLO.len())
+        });
 
     let mut file = File::from_std(file);
 
@@ -225,8 +194,11 @@ fn read_err_then_read_success() {
 
 #[test]
 fn open_write() {
-    let (mock, file) = sys::File::mock();
-    mock.write(HELLO);
+    let mut file = MockFile::default();
+    file.expect_inner_write()
+        .once()
+        .with(eq(HELLO))
+        .returning(|buf| Ok(buf.len()));
 
     let mut file = File::from_std(file);
 
@@ -235,12 +207,10 @@ fn open_write() {
     assert_eq!(0, pool::len());
     assert_ready_ok!(t.poll());
 
-    assert_eq!(1, mock.remaining());
     assert_eq!(1, pool::len());
 
     pool::run_one();
 
-    assert_eq!(0, mock.remaining());
     assert!(!t.is_woken());
 
     let mut t = task::spawn(file.flush());
@@ -249,7 +219,7 @@ fn open_write() {
 
 #[test]
 fn flush_while_idle() {
-    let (_mock, file) = sys::File::mock();
+    let file = MockFile::default();
 
     let mut file = File::from_std(file);
 
@@ -271,13 +241,42 @@ fn read_with_buffer_larger_than_max() {
     for i in 0..(chunk_d - 1) {
         data.push((i % 151) as u8);
     }
+    let data = Arc::new(data);
+    let d0 = data.clone();
+    let d1 = data.clone();
+    let d2 = data.clone();
+    let d3 = data.clone();
 
-    let (mock, file) = sys::File::mock();
-    mock.read(&data[0..chunk_a])
-        .read(&data[chunk_a..chunk_b])
-        .read(&data[chunk_b..chunk_c])
-        .read(&data[chunk_c..]);
-
+    let mut seq = Sequence::new();
+    let mut file = MockFile::default();
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(move |buf| {
+            buf[0..chunk_a].copy_from_slice(&d0[0..chunk_a]);
+            Ok(chunk_a)
+        });
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(move |buf| {
+            buf[..chunk_a].copy_from_slice(&d1[chunk_a..chunk_b]);
+            Ok(chunk_b - chunk_a)
+        });
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(move |buf| {
+            buf[..chunk_a].copy_from_slice(&d2[chunk_b..chunk_c]);
+            Ok(chunk_c - chunk_b)
+        });
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(move |buf| {
+            buf[..chunk_a - 1].copy_from_slice(&d3[chunk_c..]);
+            Ok(chunk_a - 1)
+        });
     let mut file = File::from_std(file);
 
     let mut actual = vec![0; chunk_d];
@@ -296,8 +295,7 @@ fn read_with_buffer_larger_than_max() {
         pos += n;
     }
 
-    assert_eq!(mock.remaining(), 0);
-    assert_eq!(data, &actual[..data.len()]);
+    assert_eq!(&data[..], &actual[..data.len()]);
 }
 
 #[test]
@@ -314,12 +312,34 @@ fn write_with_buffer_larger_than_max() {
     for i in 0..(chunk_d - 1) {
         data.push((i % 151) as u8);
     }
+    let data = Arc::new(data);
+    let d0 = data.clone();
+    let d1 = data.clone();
+    let d2 = data.clone();
+    let d3 = data.clone();
 
-    let (mock, file) = sys::File::mock();
-    mock.write(&data[0..chunk_a])
-        .write(&data[chunk_a..chunk_b])
-        .write(&data[chunk_b..chunk_c])
-        .write(&data[chunk_c..]);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .withf(move |buf| buf == &d0[0..chunk_a])
+        .returning(|buf| Ok(buf.len()));
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .withf(move |buf| buf == &d1[chunk_a..chunk_b])
+        .returning(|buf| Ok(buf.len()));
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .withf(move |buf| buf == &d2[chunk_b..chunk_c])
+        .returning(|buf| Ok(buf.len()));
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .withf(move |buf| buf == &d3[chunk_c..chunk_d - 1])
+        .returning(|buf| Ok(buf.len()));
 
     let mut file = File::from_std(file);
 
@@ -344,14 +364,22 @@ fn write_with_buffer_larger_than_max() {
     }
 
     pool::run_one();
-
-    assert_eq!(mock.remaining(), 0);
 }
 
 #[test]
 fn write_twice_before_dispatch() {
-    let (mock, file) = sys::File::mock();
-    mock.write(HELLO).write(FOO);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(HELLO))
+        .returning(|buf| Ok(buf.len()));
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(FOO))
+        .returning(|buf| Ok(buf.len()));
 
     let mut file = File::from_std(file);
 
@@ -380,10 +408,24 @@ fn write_twice_before_dispatch() {
 
 #[test]
 fn incomplete_read_followed_by_write() {
-    let (mock, file) = sys::File::mock();
-    mock.read(HELLO)
-        .seek_current_ok(-(HELLO.len() as i64), 0)
-        .write(FOO);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|buf| {
+            buf[0..HELLO.len()].copy_from_slice(HELLO);
+            Ok(HELLO.len())
+        });
+    file.expect_inner_seek()
+        .once()
+        .with(eq(SeekFrom::Current(-(HELLO.len() as i64))))
+        .in_sequence(&mut seq)
+        .returning(|_| Ok(0));
+    file.expect_inner_write()
+        .once()
+        .with(eq(FOO))
+        .returning(|_| Ok(FOO.len()));
 
     let mut file = File::from_std(file);
 
@@ -406,8 +448,25 @@ fn incomplete_read_followed_by_write() {
 
 #[test]
 fn incomplete_partial_read_followed_by_write() {
-    let (mock, file) = sys::File::mock();
-    mock.read(HELLO).seek_current_ok(-10, 0).write(FOO);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|buf| {
+            buf[0..HELLO.len()].copy_from_slice(HELLO);
+            Ok(HELLO.len())
+        });
+    file.expect_inner_seek()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(SeekFrom::Current(-10)))
+        .returning(|_| Ok(0));
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(FOO))
+        .returning(|_| Ok(FOO.len()));
 
     let mut file = File::from_std(file);
 
@@ -433,10 +492,25 @@ fn incomplete_partial_read_followed_by_write() {
 
 #[test]
 fn incomplete_read_followed_by_flush() {
-    let (mock, file) = sys::File::mock();
-    mock.read(HELLO)
-        .seek_current_ok(-(HELLO.len() as i64), 0)
-        .write(FOO);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|buf| {
+            buf[0..HELLO.len()].copy_from_slice(HELLO);
+            Ok(HELLO.len())
+        });
+    file.expect_inner_seek()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(SeekFrom::Current(-(HELLO.len() as i64))))
+        .returning(|_| Ok(0));
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(FOO))
+        .returning(|_| Ok(FOO.len()));
 
     let mut file = File::from_std(file);
 
@@ -458,8 +532,18 @@ fn incomplete_read_followed_by_flush() {
 
 #[test]
 fn incomplete_flush_followed_by_write() {
-    let (mock, file) = sys::File::mock();
-    mock.write(HELLO).write(FOO);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(HELLO))
+        .returning(|_| Ok(HELLO.len()));
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(FOO))
+        .returning(|_| Ok(FOO.len()));
 
     let mut file = File::from_std(file);
 
@@ -484,8 +568,10 @@ fn incomplete_flush_followed_by_write() {
 
 #[test]
 fn read_err() {
-    let (mock, file) = sys::File::mock();
-    mock.read_err();
+    let mut file = MockFile::default();
+    file.expect_inner_read()
+        .once()
+        .returning(|_| Err(io::ErrorKind::Other.into()));
 
     let mut file = File::from_std(file);
 
@@ -502,8 +588,10 @@ fn read_err() {
 
 #[test]
 fn write_write_err() {
-    let (mock, file) = sys::File::mock();
-    mock.write_err();
+    let mut file = MockFile::default();
+    file.expect_inner_write()
+        .once()
+        .returning(|_| Err(io::ErrorKind::Other.into()));
 
     let mut file = File::from_std(file);
 
@@ -518,8 +606,19 @@ fn write_write_err() {
 
 #[test]
 fn write_read_write_err() {
-    let (mock, file) = sys::File::mock();
-    mock.write_err().read(HELLO);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|_| Err(io::ErrorKind::Other.into()));
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|buf| {
+            buf[0..HELLO.len()].copy_from_slice(HELLO);
+            Ok(HELLO.len())
+        });
 
     let mut file = File::from_std(file);
 
@@ -541,8 +640,19 @@ fn write_read_write_err() {
 
 #[test]
 fn write_read_flush_err() {
-    let (mock, file) = sys::File::mock();
-    mock.write_err().read(HELLO);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|_| Err(io::ErrorKind::Other.into()));
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|buf| {
+            buf[0..HELLO.len()].copy_from_slice(HELLO);
+            Ok(HELLO.len())
+        });
 
     let mut file = File::from_std(file);
 
@@ -564,8 +674,17 @@ fn write_read_flush_err() {
 
 #[test]
 fn write_seek_write_err() {
-    let (mock, file) = sys::File::mock();
-    mock.write_err().seek_start_ok(0);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|_| Err(io::ErrorKind::Other.into()));
+    file.expect_inner_seek()
+        .once()
+        .with(eq(SeekFrom::Start(0)))
+        .in_sequence(&mut seq)
+        .returning(|_| Ok(0));
 
     let mut file = File::from_std(file);
 
@@ -587,8 +706,17 @@ fn write_seek_write_err() {
 
 #[test]
 fn write_seek_flush_err() {
-    let (mock, file) = sys::File::mock();
-    mock.write_err().seek_start_ok(0);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|_| Err(io::ErrorKind::Other.into()));
+    file.expect_inner_seek()
+        .once()
+        .with(eq(SeekFrom::Start(0)))
+        .in_sequence(&mut seq)
+        .returning(|_| Ok(0));
 
     let mut file = File::from_std(file);
 
@@ -610,8 +738,14 @@ fn write_seek_flush_err() {
 
 #[test]
 fn sync_all_ordered_after_write() {
-    let (mock, file) = sys::File::mock();
-    mock.write(HELLO).sync_all();
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(HELLO))
+        .returning(|_| Ok(HELLO.len()));
+    file.expect_sync_all().once().returning(|| Ok(()));
 
     let mut file = File::from_std(file);
     let mut t = task::spawn(file.write(HELLO));
@@ -635,8 +769,16 @@ fn sync_all_ordered_after_write() {
 
 #[test]
 fn sync_all_err_ordered_after_write() {
-    let (mock, file) = sys::File::mock();
-    mock.write(HELLO).sync_all_err();
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(HELLO))
+        .returning(|_| Ok(HELLO.len()));
+    file.expect_sync_all()
+        .once()
+        .returning(|| Err(io::ErrorKind::Other.into()));
 
     let mut file = File::from_std(file);
     let mut t = task::spawn(file.write(HELLO));
@@ -660,8 +802,14 @@ fn sync_all_err_ordered_after_write() {
 
 #[test]
 fn sync_data_ordered_after_write() {
-    let (mock, file) = sys::File::mock();
-    mock.write(HELLO).sync_data();
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(HELLO))
+        .returning(|_| Ok(HELLO.len()));
+    file.expect_sync_data().once().returning(|| Ok(()));
 
     let mut file = File::from_std(file);
     let mut t = task::spawn(file.write(HELLO));
@@ -685,8 +833,16 @@ fn sync_data_ordered_after_write() {
 
 #[test]
 fn sync_data_err_ordered_after_write() {
-    let (mock, file) = sys::File::mock();
-    mock.write(HELLO).sync_data_err();
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(HELLO))
+        .returning(|_| Ok(HELLO.len()));
+    file.expect_sync_data()
+        .once()
+        .returning(|| Err(io::ErrorKind::Other.into()));
 
     let mut file = File::from_std(file);
     let mut t = task::spawn(file.write(HELLO));
@@ -710,17 +866,15 @@ fn sync_data_err_ordered_after_write() {
 
 #[test]
 fn open_set_len_ok() {
-    let (mock, file) = sys::File::mock();
-    mock.set_len(123);
+    let mut file = MockFile::default();
+    file.expect_set_len().with(eq(123)).returning(|_| Ok(()));
 
     let file = File::from_std(file);
     let mut t = task::spawn(file.set_len(123));
 
     assert_pending!(t.poll());
-    assert_eq!(1, mock.remaining());
 
     pool::run_one();
-    assert_eq!(0, mock.remaining());
 
     assert!(t.is_woken());
     assert_ready_ok!(t.poll());
@@ -728,17 +882,17 @@ fn open_set_len_ok() {
 
 #[test]
 fn open_set_len_err() {
-    let (mock, file) = sys::File::mock();
-    mock.set_len_err(123);
+    let mut file = MockFile::default();
+    file.expect_set_len()
+        .with(eq(123))
+        .returning(|_| Err(io::ErrorKind::Other.into()));
 
     let file = File::from_std(file);
     let mut t = task::spawn(file.set_len(123));
 
     assert_pending!(t.poll());
-    assert_eq!(1, mock.remaining());
 
     pool::run_one();
-    assert_eq!(0, mock.remaining());
 
     assert!(t.is_woken());
     assert_ready_err!(t.poll());
@@ -746,11 +900,32 @@ fn open_set_len_err() {
 
 #[test]
 fn partial_read_set_len_ok() {
-    let (mock, file) = sys::File::mock();
-    mock.read(HELLO)
-        .seek_current_ok(-14, 0)
-        .set_len(123)
-        .read(FOO);
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|buf| {
+            buf[0..HELLO.len()].copy_from_slice(HELLO);
+            Ok(HELLO.len())
+        });
+    file.expect_inner_seek()
+        .once()
+        .with(eq(SeekFrom::Current(-(HELLO.len() as i64))))
+        .in_sequence(&mut seq)
+        .returning(|_| Ok(0));
+    file.expect_set_len()
+        .once()
+        .in_sequence(&mut seq)
+        .with(eq(123))
+        .returning(|_| Ok(()));
+    file.expect_inner_read()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|buf| {
+            buf[0..FOO.len()].copy_from_slice(FOO);
+            Ok(FOO.len())
+        });
 
     let mut buf = [0; 32];
     let mut file = File::from_std(file);

tokio/src/fs/mocks.rs

@@ -0,0 +1,136 @@
+//! Mock version of std::fs::File;
+use mockall::mock;
+
+use crate::sync::oneshot;
+use std::{
+    cell::RefCell,
+    collections::VecDeque,
+    fs::{Metadata, Permissions},
+    future::Future,
+    io::{self, Read, Seek, SeekFrom, Write},
+    path::PathBuf,
+    pin::Pin,
+    task::{Context, Poll},
+};
+
+mock! {
+    #[derive(Debug)]
+    pub File {
+        pub fn create(pb: PathBuf) -> io::Result<Self>;
+        // These inner_ methods exist because std::fs::File has two
+        // implementations for each of these methods: one on "&mut self" and
+        // one on "&&self".  Defining both of those in terms of an inner_ method
+        // allows us to specify the expectation the same way, regardless of
+        // which method is used.
+        pub fn inner_flush(&self) -> io::Result<()>;
+        pub fn inner_read(&self, dst: &mut [u8]) -> io::Result<usize>;
+        pub fn inner_seek(&self, pos: SeekFrom) -> io::Result<u64>;
+        pub fn inner_write(&self, src: &[u8]) -> io::Result<usize>;
+        pub fn metadata(&self) -> io::Result<Metadata>;
+        pub fn open(pb: PathBuf) -> io::Result<Self>;
+        pub fn set_len(&self, size: u64) -> io::Result<()>;
+        pub fn set_permissions(&self, _perm: Permissions) -> io::Result<()>;
+        pub fn sync_all(&self) -> io::Result<()>;
+        pub fn sync_data(&self) -> io::Result<()>;
+        pub fn try_clone(&self) -> io::Result<Self>;
+    }
+    #[cfg(windows)]
+    impl std::os::windows::io::AsRawHandle for File {
+        fn as_raw_handle(&self) -> std::os::windows::io::RawHandle;
+    }
+    #[cfg(windows)]
+    impl std::os::windows::io::FromRawHandle for File {
+        unsafe fn from_raw_handle(h: std::os::windows::io::RawHandle) -> Self;
+    }
+    #[cfg(unix)]
+    impl std::os::unix::io::AsRawFd for File {
+        fn as_raw_fd(&self) -> std::os::unix::io::RawFd;
+    }
+
+    #[cfg(unix)]
+    impl std::os::unix::io::FromRawFd for File {
+        unsafe fn from_raw_fd(h: std::os::unix::io::RawFd) -> Self;
+    }
+}
+
+impl Read for MockFile {
+    fn read(&mut self, dst: &mut [u8]) -> io::Result<usize> {
+        self.inner_read(dst)
+    }
+}
+
+impl Read for &'_ MockFile {
+    fn read(&mut self, dst: &mut [u8]) -> io::Result<usize> {
+        self.inner_read(dst)
+    }
+}
+
+impl Seek for &'_ MockFile {
+    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
+        self.inner_seek(pos)
+    }
+}
+
+impl Write for &'_ MockFile {
+    fn write(&mut self, src: &[u8]) -> io::Result<usize> {
+        self.inner_write(src)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.inner_flush()
+    }
+}
+
+thread_local! {
+    static QUEUE: RefCell<VecDeque<Box<dyn FnOnce() + Send>>> = RefCell::new(VecDeque::new())
+}
+
+#[derive(Debug)]
+pub(super) struct JoinHandle<T> {
+    rx: oneshot::Receiver<T>,
+}
+
+pub(super) fn spawn_blocking<F, R>(f: F) -> JoinHandle<R>
+where
+    F: FnOnce() -> R + Send + 'static,
+    R: Send + 'static,
+{
+    let (tx, rx) = oneshot::channel();
+    let task = Box::new(move || {
+        let _ = tx.send(f());
+    });
+
+    QUEUE.with(|cell| cell.borrow_mut().push_back(task));
+
+    JoinHandle { rx }
+}
+
+impl<T> Future for JoinHandle<T> {
+    type Output = Result<T, io::Error>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        use std::task::Poll::*;
+
+        match Pin::new(&mut self.rx).poll(cx) {
+            Ready(Ok(v)) => Ready(Ok(v)),
+            Ready(Err(e)) => panic!("error = {:?}", e),
+            Pending => Pending,
+        }
+    }
+}
+
+pub(super) mod pool {
+    use super::*;
+
+    pub(in super::super) fn len() -> usize {
+        QUEUE.with(|cell| cell.borrow().len())
+    }
+
+    pub(in super::super) fn run_one() {
+        let task = QUEUE
+            .with(|cell| cell.borrow_mut().pop_front())
+            .expect("expected task to run, but none ready");
+
+        task();
+    }
+}

tokio/src/fs/mod.rs

@@ -84,6 +84,9 @@ pub use self::write::write;
 mod copy;
 pub use self::copy::copy;
 
+#[cfg(test)]
+mod mocks;
+
 feature! {
     #![unix]
 
@@ -103,12 +106,17 @@ feature! {
 
 use std::io;
 
+#[cfg(not(test))]
+use crate::blocking::spawn_blocking;
+#[cfg(test)]
+use mocks::spawn_blocking;
+
 pub(crate) async fn asyncify<F, T>(f: F) -> io::Result<T>
 where
     F: FnOnce() -> io::Result<T> + Send + 'static,
     T: Send + 'static,
 {
-    match sys::run(f).await {
+    match spawn_blocking(f).await {
         Ok(res) => res,
         Err(_) => Err(io::Error::new(
             io::ErrorKind::Other,
@@ -116,12 +124,3 @@ where
         )),
     }
 }
-
-/// Types in this module can be mocked out in tests.
-mod sys {
-    pub(crate) use std::fs::File;
-
-    // TODO: don't rename
-    pub(crate) use crate::blocking::spawn_blocking as run;
-    pub(crate) use crate::blocking::JoinHandle as Blocking;
-}

tokio/src/fs/open_options.rs

@@ -3,6 +3,13 @@ use crate::fs::{asyncify, File};
 use std::io;
 use std::path::Path;
 
+#[cfg(test)]
+mod mock_open_options;
+#[cfg(test)]
+use mock_open_options::MockOpenOptions as StdOpenOptions;
+#[cfg(not(test))]
+use std::fs::OpenOptions as StdOpenOptions;
+
 /// Options and flags which can be used to configure how a file is opened.
 ///
 /// This builder exposes the ability to configure how a [`File`] is opened and
@@ -69,7 +76,7 @@ use std::path::Path;
 /// }
 /// ```
 #[derive(Clone, Debug)]
-pub struct OpenOptions(std::fs::OpenOptions);
+pub struct OpenOptions(StdOpenOptions);
 
 impl OpenOptions {
     /// Creates a blank new set of options ready for configuration.
@@ -89,7 +96,7 @@ impl OpenOptions {
     /// let future = options.read(true).open("foo.txt");
     /// ```
     pub fn new() -> OpenOptions {
-        OpenOptions(std::fs::OpenOptions::new())
+        OpenOptions(StdOpenOptions::new())
     }
 
     /// Sets the option for read access.
@@ -384,7 +391,7 @@ impl OpenOptions {
     }
 
     /// Returns a mutable reference to the underlying `std::fs::OpenOptions`
-    pub(super) fn as_inner_mut(&mut self) -> &mut std::fs::OpenOptions {
+    pub(super) fn as_inner_mut(&mut self) -> &mut StdOpenOptions {
         &mut self.0
     }
 }
@@ -645,8 +652,8 @@ feature! {
     }
 }
 
-impl From<std::fs::OpenOptions> for OpenOptions {
-    fn from(options: std::fs::OpenOptions) -> OpenOptions {
+impl From<StdOpenOptions> for OpenOptions {
+    fn from(options: StdOpenOptions) -> OpenOptions {
         OpenOptions(options)
     }
 }

tokio/src/fs/open_options/mock_open_options.rs

@@ -0,0 +1,38 @@
+//! Mock version of std::fs::OpenOptions;
+use mockall::mock;
+
+use crate::fs::mocks::MockFile;
+#[cfg(unix)]
+use std::os::unix::fs::OpenOptionsExt;
+#[cfg(windows)]
+use std::os::windows::fs::OpenOptionsExt;
+use std::{io, path::Path};
+
+mock! {
+    #[derive(Debug)]
+    pub OpenOptions {
+        pub fn append(&mut self, append: bool) -> &mut Self;
+        pub fn create(&mut self, create: bool) -> &mut Self;
+        pub fn create_new(&mut self, create_new: bool) -> &mut Self;
+        pub fn open<P: AsRef<Path> + 'static>(&self, path: P) -> io::Result<MockFile>;
+        pub fn read(&mut self, read: bool) -> &mut Self;
+        pub fn truncate(&mut self, truncate: bool) -> &mut Self;
+        pub fn write(&mut self, write: bool) -> &mut Self;
+    }
+    impl Clone for OpenOptions {
+        fn clone(&self) -> Self;
+    }
+    #[cfg(unix)]
+    impl OpenOptionsExt for OpenOptions {
+        fn custom_flags(&mut self, flags: i32) -> &mut Self;
+        fn mode(&mut self, mode: u32) -> &mut Self;
+    }
+    #[cfg(windows)]
+    impl OpenOptionsExt for OpenOptions {
+        fn access_mode(&mut self, access: u32) -> &mut Self;
+        fn share_mode(&mut self, val: u32) -> &mut Self;
+        fn custom_flags(&mut self, flags: u32) -> &mut Self;
+        fn attributes(&mut self, val: u32) -> &mut Self;
+        fn security_qos_flags(&mut self, flags: u32) -> &mut Self;
+    }
+}

tokio/src/fs/read.rs

@@ -13,8 +13,12 @@ use std::{io, path::Path};
 /// buffer based on the file size when available, so it is generally faster than
 /// reading into a vector created with `Vec::new()`.
 ///
+/// This operation is implemented by running the equivalent blocking operation
+/// on a separate thread pool using [`spawn_blocking`].
+///
 /// [`File::open`]: super::File::open
 /// [`read_to_end`]: crate::io::AsyncReadExt::read_to_end
+/// [`spawn_blocking`]: crate::task::spawn_blocking
 ///
 /// # Errors
 ///

tokio/src/fs/read_dir.rs

@@ -1,4 +1,4 @@
-use crate::fs::{asyncify, sys};
+use crate::fs::asyncify;
 
 use std::ffi::OsString;
 use std::fs::{FileType, Metadata};
@@ -10,9 +10,23 @@ use std::sync::Arc;
 use std::task::Context;
 use std::task::Poll;
 
+#[cfg(test)]
+use super::mocks::spawn_blocking;
+#[cfg(test)]
+use super::mocks::JoinHandle;
+#[cfg(not(test))]
+use crate::blocking::spawn_blocking;
+#[cfg(not(test))]
+use crate::blocking::JoinHandle;
+
 /// Returns a stream over the entries within a directory.
 ///
 /// This is an async version of [`std::fs::read_dir`](std::fs::read_dir)
+///
+/// This operation is implemented by running the equivalent blocking
+/// operation on a separate thread pool using [`spawn_blocking`].
+///
+/// [`spawn_blocking`]: crate::task::spawn_blocking
 pub async fn read_dir(path: impl AsRef<Path>) -> io::Result<ReadDir> {
     let path = path.as_ref().to_owned();
     let std = asyncify(|| std::fs::read_dir(path)).await?;
@@ -45,11 +59,15 @@ pub struct ReadDir(State);
 #[derive(Debug)]
 enum State {
     Idle(Option<std::fs::ReadDir>),
-    Pending(sys::Blocking<(Option<io::Result<std::fs::DirEntry>>, std::fs::ReadDir)>),
+    Pending(JoinHandle<(Option<io::Result<std::fs::DirEntry>>, std::fs::ReadDir)>),
 }
 
 impl ReadDir {
     /// Returns the next entry in the directory stream.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancellation safe.
     pub async fn next_entry(&mut self) -> io::Result<Option<DirEntry>> {
         use crate::future::poll_fn;
         poll_fn(|cx| self.poll_next_entry(cx)).await
@@ -79,7 +97,7 @@ impl ReadDir {
                 State::Idle(ref mut std) => {
                     let mut std = std.take().unwrap();
 
-                    self.0 = State::Pending(sys::run(move || {
+                    self.0 = State::Pending(spawn_blocking(move || {
                         let ret = std.next();
                         (ret, std)
                     }));

tokio/src/fs/read_to_string.rs

@@ -7,6 +7,10 @@ use std::{io, path::Path};
 ///
 /// This is the async equivalent of [`std::fs::read_to_string`][std].
 ///
+/// This operation is implemented by running the equivalent blocking operation
+/// on a separate thread pool using [`spawn_blocking`].
+///
+/// [`spawn_blocking`]: crate::task::spawn_blocking
 /// [std]: fn@std::fs::read_to_string
 ///
 /// # Examples

tokio/src/fs/write.rs

@@ -7,6 +7,10 @@ use std::{io, path::Path};
 ///
 /// This is the async equivalent of [`std::fs::write`][std].
 ///
+/// This operation is implemented by running the equivalent blocking operation
+/// on a separate thread pool using [`spawn_blocking`].
+///
+/// [`spawn_blocking`]: crate::task::spawn_blocking
 /// [std]: fn@std::fs::write
 ///
 /// # Examples

tokio/src/future/mod.rs

@@ -22,3 +22,14 @@ cfg_sync! {
     mod block_on;
     pub(crate) use block_on::block_on;
 }
+
+cfg_trace! {
+    mod trace;
+    pub(crate) use trace::InstrumentedFuture as Future;
+}
+
+cfg_not_trace! {
+    cfg_rt! {
+        pub(crate) use std::future::Future;
+    }
+}

tokio/src/future/trace.rs

@@ -0,0 +1,11 @@
+use std::future::Future;
+
+pub(crate) trait InstrumentedFuture: Future {
+    fn id(&self) -> Option<tracing::Id>;
+}
+
+impl<F: Future> InstrumentedFuture for tracing::instrument::Instrumented<F> {
+    fn id(&self) -> Option<tracing::Id> {
+        self.span().id()
+    }
+}

tokio/src/io/async_fd.rs

@@ -540,6 +540,16 @@ impl<'a, Inner: AsRawFd> AsyncFdReadyGuard<'a, Inner> {
             result => Ok(result),
         }
     }
+
+    /// Returns a shared reference to the inner [`AsyncFd`].
+    pub fn get_ref(&self) -> &AsyncFd<Inner> {
+        self.async_fd
+    }
+
+    /// Returns a shared reference to the backing object of the inner [`AsyncFd`].
+    pub fn get_inner(&self) -> &Inner {
+        self.get_ref().get_ref()
+    }
 }
 
 impl<'a, Inner: AsRawFd> AsyncFdReadyMutGuard<'a, Inner> {
@@ -601,6 +611,26 @@ impl<'a, Inner: AsRawFd> AsyncFdReadyMutGuard<'a, Inner> {
             result => Ok(result),
         }
     }
+
+    /// Returns a shared reference to the inner [`AsyncFd`].
+    pub fn get_ref(&self) -> &AsyncFd<Inner> {
+        self.async_fd
+    }
+
+    /// Returns a mutable reference to the inner [`AsyncFd`].
+    pub fn get_mut(&mut self) -> &mut AsyncFd<Inner> {
+        self.async_fd
+    }
+
+    /// Returns a shared reference to the backing object of the inner [`AsyncFd`].
+    pub fn get_inner(&self) -> &Inner {
+        self.get_ref().get_ref()
+    }
+
+    /// Returns a mutable reference to the backing object of the inner [`AsyncFd`].
+    pub fn get_inner_mut(&mut self) -> &mut Inner {
+        self.get_mut().get_mut()
+    }
 }
 
 impl<'a, T: std::fmt::Debug + AsRawFd> std::fmt::Debug for AsyncFdReadyGuard<'a, T> {

tokio/src/io/async_write.rs

@@ -45,7 +45,11 @@ use std::task::{Context, Poll};
 pub trait AsyncWrite {
     /// Attempt to write bytes from `buf` into the object.
     ///
-    /// On success, returns `Poll::Ready(Ok(num_bytes_written))`.
+    /// On success, returns `Poll::Ready(Ok(num_bytes_written))`. If successful,
+    /// then it must be guaranteed that `n <= buf.len()`. A return value of `0`
+    /// typically means that the underlying object is no longer able to accept
+    /// bytes and will likely not be able to in the future as well, or that the
+    /// buffer provided is empty.
     ///
     /// If the object is not ready for writing, the method returns
     /// `Poll::Pending` and arranges for the current task (via

tokio/src/io/driver/interest.rs

@@ -58,7 +58,7 @@ impl Interest {
         self.0.is_writable()
     }
 
-    /// Add together two `Interst` values.
+    /// Add together two `Interest` values.
     ///
     /// This function works from a `const` context.
     ///

tokio/src/io/driver/mod.rs

@@ -96,7 +96,7 @@ const ADDRESS: bit::Pack = bit::Pack::least_significant(24);
 //
 // The generation prevents a race condition where a slab slot is reused for a
 // new socket while the I/O driver is about to apply a readiness event. The
-// generaton value is checked when setting new readiness. If the generation do
+// generation value is checked when setting new readiness. If the generation do
 // not match, then the readiness event is discarded.
 const GENERATION: bit::Pack = ADDRESS.then(7);
 

tokio/src/io/driver/scheduled_io.rs

@@ -84,9 +84,9 @@ cfg_io_readiness! {
 
 // The `ScheduledIo::readiness` (`AtomicUsize`) is packed full of goodness.
 //
-// | reserved | generation |  driver tick | readinesss |
-// |----------+------------+--------------+------------|
-// |   1 bit  |   7 bits   +    8 bits    +   16 bits  |
+// | reserved | generation |  driver tick | readiness |
+// |----------+------------+--------------+-----------|
+// |   1 bit  |   7 bits   +    8 bits    +   16 bits |
 
 const READINESS: bit::Pack = bit::Pack::least_significant(16);
 

tokio/src/io/poll_evented.rs

@@ -40,9 +40,8 @@ cfg_io_driver! {
     /// [`poll_read_ready`] again will also indicate read readiness.
     ///
     /// When the operation is attempted and is unable to succeed due to the I/O
-    /// resource not being ready, the caller must call `clear_read_ready` or
-    /// `clear_write_ready`. This clears the readiness state until a new
-    /// readiness event is received.
+    /// resource not being ready, the caller must call `clear_readiness`.
+    /// This clears the readiness state until a new readiness event is received.
     ///
     /// This allows the caller to implement additional functions. For example,
     /// [`TcpListener`] implements poll_accept by using [`poll_read_ready`] and

tokio/src/io/read_buf.rs

@@ -45,7 +45,7 @@ impl<'a> ReadBuf<'a> {
 
     /// Creates a new `ReadBuf` from a fully uninitialized buffer.
     ///
-    /// Use `assume_init` if part of the buffer is known to be already inintialized.
+    /// Use `assume_init` if part of the buffer is known to be already initialized.
     #[inline]
     pub fn uninit(buf: &'a mut [MaybeUninit<u8>]) -> ReadBuf<'a> {
         ReadBuf {
@@ -85,7 +85,7 @@ impl<'a> ReadBuf<'a> {
     #[inline]
     pub fn take(&mut self, n: usize) -> ReadBuf<'_> {
         let max = std::cmp::min(self.remaining(), n);
-        // Saftey: We don't set any of the `unfilled_mut` with `MaybeUninit::uninit`.
+        // Safety: We don't set any of the `unfilled_mut` with `MaybeUninit::uninit`.
         unsafe { ReadBuf::uninit(&mut self.unfilled_mut()[..max]) }
     }
 
@@ -217,7 +217,7 @@ impl<'a> ReadBuf<'a> {
     ///
     /// # Panics
     ///
-    /// Panics if the filled region of the buffer would become larger than the intialized region.
+    /// Panics if the filled region of the buffer would become larger than the initialized region.
     #[inline]
     pub fn set_filled(&mut self, n: usize) {
         assert!(

tokio/src/io/split.rs

@@ -63,7 +63,7 @@ impl<T> ReadHalf<T> {
     /// Checks if this `ReadHalf` and some `WriteHalf` were split from the same
     /// stream.
     pub fn is_pair_of(&self, other: &WriteHalf<T>) -> bool {
-        other.is_pair_of(&self)
+        other.is_pair_of(self)
     }
 
     /// Reunites with a previously split `WriteHalf`.

tokio/src/io/stdio_common.rs

@@ -52,10 +52,10 @@ where
 
         buf = &buf[..crate::io::blocking::MAX_BUF];
 
-        // Now there are two possibilites.
+        // Now there are two possibilities.
         // If caller gave is binary buffer, we **should not** shrink it
         // anymore, because excessive shrinking hits performance.
-        // If caller gave as binary buffer, we  **must** additionaly
+        // If caller gave as binary buffer, we  **must** additionally
         // shrink it to strip incomplete char at the end of buffer.
         // that's why check we will perform now is allowed to have
         // false-positive.

tokio/src/io/util/async_buf_read_ext.rs

@@ -1,3 +1,4 @@
+use crate::io::util::fill_buf::{fill_buf, FillBuf};
 use crate::io::util::lines::{lines, Lines};
 use crate::io::util::read_line::{read_line, ReadLine};
 use crate::io::util::read_until::{read_until, ReadUntil};
@@ -36,6 +37,18 @@ cfg_io_util! {
         /// [`fill_buf`]: AsyncBufRead::poll_fill_buf
         /// [`ErrorKind::Interrupted`]: std::io::ErrorKind::Interrupted
         ///
+        /// # Cancel safety
+        ///
+        /// If the method is used as the event in a
+        /// [`tokio::select!`](crate::select) statement and some other branch
+        /// completes first, then some data may have been partially read. Any
+        /// partially read bytes are appended to `buf`, and the method can be
+        /// called again to continue reading until `byte`.
+        ///
+        /// This method returns the total number of bytes read. If you cancel
+        /// the call to `read_until` and then call it again to continue reading,
+        /// the counter is reset.
+        ///
         /// # Examples
         ///
         /// [`std::io::Cursor`][`Cursor`] is a type that implements `BufRead`. In
@@ -114,6 +127,30 @@ cfg_io_util! {
         ///
         /// [`read_until`]: AsyncBufReadExt::read_until
         ///
+        /// # Cancel safety
+        ///
+        /// This method is not cancellation safe. If the method is used as the
+        /// event in a [`tokio::select!`](crate::select) statement and some
+        /// other branch completes first, then some data may have been partially
+        /// read, and this data is lost. There are no guarantees regarding the
+        /// contents of `buf` when the call is cancelled. The current
+        /// implementation replaces `buf` with the empty string, but this may
+        /// change in the future.
+        ///
+        /// This function does not behave like [`read_until`] because of the
+        /// requirement that a string contains only valid utf-8. If you need a
+        /// cancellation safe `read_line`, there are three options:
+        ///
+        ///  * Call [`read_until`] with a newline character and manually perform the utf-8 check.
+        ///  * The stream returned by [`lines`] has a cancellation safe
+        ///    [`next_line`] method.
+        ///  * Use [`tokio_util::codec::LinesCodec`][LinesCodec].
+        ///
+        /// [LinesCodec]: https://docs.rs/tokio-util/0.6/tokio_util/codec/struct.LinesCodec.html
+        /// [`read_until`]: Self::read_until
+        /// [`lines`]: Self::lines
+        /// [`next_line`]: crate::io::Lines::next_line
+        ///
         /// # Examples
         ///
         /// [`std::io::Cursor`][`Cursor`] is a type that implements
@@ -173,10 +210,11 @@ cfg_io_util! {
         /// [`BufRead::split`](std::io::BufRead::split).
         ///
         /// The stream returned from this function will yield instances of
-        /// [`io::Result`]`<`[`Vec<u8>`]`>`. Each vector returned will *not* have
+        /// [`io::Result`]`<`[`Option`]`<`[`Vec<u8>`]`>>`. Each vector returned will *not* have
         /// the delimiter byte at the end.
         ///
         /// [`io::Result`]: std::io::Result
+        /// [`Option`]: core::option::Option
         /// [`Vec<u8>`]: std::vec::Vec
         ///
         /// # Errors
@@ -206,14 +244,68 @@ cfg_io_util! {
             split(self, byte)
         }
 
+        /// Returns the contents of the internal buffer, filling it with more
+        /// data from the inner reader if it is empty.
+        ///
+        /// This function is a lower-level call. It needs to be paired with the
+        /// [`consume`] method to function properly. When calling this method,
+        /// none of the contents will be "read" in the sense that later calling
+        /// `read` may return the same contents. As such, [`consume`] must be
+        /// called with the number of bytes that are consumed from this buffer
+        /// to ensure that the bytes are never returned twice.
+        ///
+        /// An empty buffer returned indicates that the stream has reached EOF.
+        ///
+        /// Equivalent to:
+        ///
+        /// ```ignore
+        /// async fn fill_buf(&mut self) -> io::Result<&[u8]>;
+        /// ```
+        ///
+        /// # Errors
+        ///
+        /// This function will return an I/O error if the underlying reader was
+        /// read, but returned an error.
+        ///
+        /// [`consume`]: crate::io::AsyncBufReadExt::consume
+        fn fill_buf(&mut self) -> FillBuf<'_, Self>
+        where
+            Self: Unpin,
+        {
+            fill_buf(self)
+        }
+
+        /// Tells this buffer that `amt` bytes have been consumed from the
+        /// buffer, so they should no longer be returned in calls to [`read`].
+        ///
+        /// This function is a lower-level call. It needs to be paired with the
+        /// [`fill_buf`] method to function properly. This function does not
+        /// perform any I/O, it simply informs this object that some amount of
+        /// its buffer, returned from [`fill_buf`], has been consumed and should
+        /// no longer be returned. As such, this function may do odd things if
+        /// [`fill_buf`] isn't called before calling it.
+        ///
+        /// The `amt` must be less than the number of bytes in the buffer
+        /// returned by [`fill_buf`].
+        ///
+        /// [`read`]: crate::io::AsyncReadExt::read
+        /// [`fill_buf`]: crate::io::AsyncBufReadExt::fill_buf
+        fn consume(&mut self, amt: usize)
+        where
+            Self: Unpin,
+        {
+            std::pin::Pin::new(self).consume(amt)
+        }
+
         /// Returns a stream over the lines of this reader.
         /// This method is the async equivalent to [`BufRead::lines`](std::io::BufRead::lines).
         ///
         /// The stream returned from this function will yield instances of
-        /// [`io::Result`]`<`[`String`]`>`. Each string returned will *not* have a newline
+        /// [`io::Result`]`<`[`Option`]`<`[`String`]`>>`. Each string returned will *not* have a newline
         /// byte (the 0xA byte) or CRLF (0xD, 0xA bytes) at the end.
         ///
         /// [`io::Result`]: std::io::Result
+        /// [`Option`]: core::option::Option
         /// [`String`]: String
         ///
         /// # Errors

tokio/src/io/util/async_read_ext.rs

@@ -2,6 +2,7 @@ use crate::io::util::chain::{chain, Chain};
 use crate::io::util::read::{read, Read};
 use crate::io::util::read_buf::{read_buf, ReadBuf};
 use crate::io::util::read_exact::{read_exact, ReadExact};
+use crate::io::util::read_int::{ReadF32, ReadF32Le, ReadF64, ReadF64Le};
 use crate::io::util::read_int::{
     ReadI128, ReadI128Le, ReadI16, ReadI16Le, ReadI32, ReadI32Le, ReadI64, ReadI64Le, ReadI8,
 };
@@ -105,8 +106,10 @@ cfg_io_util! {
         /// async fn read(&mut self, buf: &mut [u8]) -> io::Result<usize>;
         /// ```
         ///
-        /// This function does not provide any guarantees about whether it
-        /// completes immediately or asynchronously
+        /// This method does not provide any guarantees about whether it
+        /// completes immediately or asynchronously.
+        ///
+        /// # Return
         ///
         /// If the return value of this method is `Ok(n)`, then it must be
         /// guaranteed that `0 <= n <= buf.len()`. A nonzero `n` value indicates
@@ -136,6 +139,12 @@ cfg_io_util! {
         /// variant will be returned. If an error is returned then it must be
         /// guaranteed that no bytes were read.
         ///
+        /// # Cancel safety
+        ///
+        /// This method is cancel safe. If you use it as the event in a
+        /// [`tokio::select!`](crate::select) statement and some other branch
+        /// completes first, then it is guaranteed that no data was read.
+        ///
         /// # Examples
         ///
         /// [`File`][crate::fs::File]s implement `Read`:
@@ -175,14 +184,19 @@ cfg_io_util! {
         /// Usually, only a single `read` syscall is issued, even if there is
         /// more space in the supplied buffer.
         ///
-        /// This function does not provide any guarantees about whether it
-        /// completes immediately or asynchronously
+        /// This method does not provide any guarantees about whether it
+        /// completes immediately or asynchronously.
         ///
         /// # Return
         ///
-        /// On a successful read, the number of read bytes is returned. If the
-        /// supplied buffer is not empty and the function returns `Ok(0)` then
-        /// the source has reached an "end-of-file" event.
+        /// A nonzero `n` value indicates that the buffer `buf` has been filled
+        /// in with `n` bytes of data from this source. If `n` is `0`, then it
+        /// can indicate one of two scenarios:
+        ///
+        /// 1. This reader has reached its "end of file" and will likely no longer
+        ///    be able to produce bytes. Note that this does not mean that the
+        ///    reader will *always* no longer be able to produce bytes.
+        /// 2. The buffer specified had a remaining capacity of zero.
         ///
         /// # Errors
         ///
@@ -190,6 +204,12 @@ cfg_io_util! {
         /// variant will be returned. If an error is returned then it must be
         /// guaranteed that no bytes were read.
         ///
+        /// # Cancel safety
+        ///
+        /// This method is cancel safe. If you use it as the event in a
+        /// [`tokio::select!`](crate::select) statement and some other branch
+        /// completes first, then it is guaranteed that no data was read.
+        ///
         /// # Examples
         ///
         /// [`File`] implements `Read` and [`BytesMut`] implements [`BufMut`]:
@@ -254,6 +274,13 @@ cfg_io_util! {
         /// it has read, but it will never read more than would be necessary to
         /// completely fill the buffer.
         ///
+        /// # Cancel safety
+        ///
+        /// This method is not cancellation safe. If the method is used as the
+        /// event in a [`tokio::select!`](crate::select) statement and some
+        /// other branch completes first, then some data may already have been
+        /// read into `buf`.
+        ///
         /// # Examples
         ///
         /// [`File`][crate::fs::File]s implement `Read`:
@@ -579,7 +606,7 @@ cfg_io_util! {
             /// async fn main() -> io::Result<()> {
             ///     let mut reader = Cursor::new(vec![0x80, 0, 0, 0, 0, 0, 0, 0]);
             ///
-            ///     assert_eq!(i64::min_value(), reader.read_i64().await?);
+            ///     assert_eq!(i64::MIN, reader.read_i64().await?);
             ///     Ok(())
             /// }
             /// ```
@@ -659,12 +686,88 @@ cfg_io_util! {
             ///         0, 0, 0, 0, 0, 0, 0, 0
             ///     ]);
             ///
-            ///     assert_eq!(i128::min_value(), reader.read_i128().await?);
+            ///     assert_eq!(i128::MIN, reader.read_i128().await?);
             ///     Ok(())
             /// }
             /// ```
             fn read_i128(&mut self) -> ReadI128;
 
+            /// Reads an 32-bit floating point type in big-endian order from the
+            /// underlying reader.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn read_f32(&mut self) -> io::Result<f32>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered reader to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncReadExt::read_exact`].
+            ///
+            /// [`AsyncReadExt::read_exact`]: AsyncReadExt::read_exact
+            ///
+            /// # Examples
+            ///
+            /// Read 32-bit floating point type from a `AsyncRead`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncReadExt};
+            ///
+            /// use std::io::Cursor;
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut reader = Cursor::new(vec![0xff, 0x7f, 0xff, 0xff]);
+            ///
+            ///     assert_eq!(f32::MIN, reader.read_f32().await?);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn read_f32(&mut self) -> ReadF32;
+
+            /// Reads an 64-bit floating point type in big-endian order from the
+            /// underlying reader.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn read_f64(&mut self) -> io::Result<f64>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered reader to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncReadExt::read_exact`].
+            ///
+            /// [`AsyncReadExt::read_exact`]: AsyncReadExt::read_exact
+            ///
+            /// # Examples
+            ///
+            /// Read 64-bit floating point type from a `AsyncRead`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncReadExt};
+            ///
+            /// use std::io::Cursor;
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut reader = Cursor::new(vec![
+            ///         0xff, 0xef, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
+            ///     ]);
+            ///
+            ///     assert_eq!(f64::MIN, reader.read_f64().await?);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn read_f64(&mut self) -> ReadF64;
+
             /// Reads an unsigned 16-bit integer in little-endian order from the
             /// underlying reader.
             ///
@@ -971,6 +1074,82 @@ cfg_io_util! {
             /// }
             /// ```
             fn read_i128_le(&mut self) -> ReadI128Le;
+
+            /// Reads an 32-bit floating point type in little-endian order from the
+            /// underlying reader.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn read_f32_le(&mut self) -> io::Result<f32>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered reader to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncReadExt::read_exact`].
+            ///
+            /// [`AsyncReadExt::read_exact`]: AsyncReadExt::read_exact
+            ///
+            /// # Examples
+            ///
+            /// Read 32-bit floating point type from a `AsyncRead`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncReadExt};
+            ///
+            /// use std::io::Cursor;
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut reader = Cursor::new(vec![0xff, 0xff, 0x7f, 0xff]);
+            ///
+            ///     assert_eq!(f32::MIN, reader.read_f32_le().await?);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn read_f32_le(&mut self) -> ReadF32Le;
+
+            /// Reads an 64-bit floating point type in little-endian order from the
+            /// underlying reader.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn read_f64_le(&mut self) -> io::Result<f64>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered reader to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncReadExt::read_exact`].
+            ///
+            /// [`AsyncReadExt::read_exact`]: AsyncReadExt::read_exact
+            ///
+            /// # Examples
+            ///
+            /// Read 64-bit floating point type from a `AsyncRead`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncReadExt};
+            ///
+            /// use std::io::Cursor;
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut reader = Cursor::new(vec![
+            ///         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0xff
+            ///     ]);
+            ///
+            ///     assert_eq!(f64::MIN, reader.read_f64_le().await?);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn read_f64_le(&mut self) -> ReadF64Le;
         }
 
         /// Reads all bytes until EOF in this source, placing them into `buf`.

tokio/src/io/util/async_write_ext.rs

@@ -4,6 +4,7 @@ use crate::io::util::write::{write, Write};
 use crate::io::util::write_all::{write_all, WriteAll};
 use crate::io::util::write_all_buf::{write_all_buf, WriteAllBuf};
 use crate::io::util::write_buf::{write_buf, WriteBuf};
+use crate::io::util::write_int::{WriteF32, WriteF32Le, WriteF64, WriteF64Le};
 use crate::io::util::write_int::{
     WriteI128, WriteI128Le, WriteI16, WriteI16Le, WriteI32, WriteI32Le, WriteI64, WriteI64Le,
     WriteI8,
@@ -97,6 +98,13 @@ cfg_io_util! {
         /// It is **not** considered an error if the entire buffer could not be
         /// written to this writer.
         ///
+        /// # Cancel safety
+        ///
+        /// This method is cancellation safe in the sense that if it is used as
+        /// the event in a [`tokio::select!`](crate::select) statement and some
+        /// other branch completes first, then it is guaranteed that no data was
+        /// written to this `AsyncWrite`.
+        ///
         /// # Examples
         ///
         /// ```no_run
@@ -129,6 +137,13 @@ cfg_io_util! {
         ///
         /// See [`AsyncWrite::poll_write_vectored`] for more details.
         ///
+        /// # Cancel safety
+        ///
+        /// This method is cancellation safe in the sense that if it is used as
+        /// the event in a [`tokio::select!`](crate::select) statement and some
+        /// other branch completes first, then it is guaranteed that no data was
+        /// written to this `AsyncWrite`.
+        ///
         /// # Examples
         ///
         /// ```no_run
@@ -195,6 +210,13 @@ cfg_io_util! {
         /// It is **not** considered an error if the entire buffer could not be
         /// written to this writer.
         ///
+        /// # Cancel safety
+        ///
+        /// This method is cancellation safe in the sense that if it is used as
+        /// the event in a [`tokio::select!`](crate::select) statement and some
+        /// other branch completes first, then it is guaranteed that no data was
+        /// written to this `AsyncWrite`.
+        ///
         /// # Examples
         ///
         /// [`File`] implements [`AsyncWrite`] and [`Cursor`]`<&[u8]>` implements [`Buf`]:
@@ -243,6 +265,7 @@ cfg_io_util! {
         ///     while buf.has_remaining() {
         ///         self.write_buf(&mut buf).await?;
         ///     }
+        ///     Ok(())
         /// }
         /// ```
         ///
@@ -254,6 +277,15 @@ cfg_io_util! {
         /// The buffer is advanced after each chunk is successfully written. After failure,
         /// `src.chunk()` will return the chunk that failed to write.
         ///
+        /// # Cancel safety
+        ///
+        /// If `write_all_buf` is used as the event in a
+        /// [`tokio::select!`](crate::select) statement and some other branch
+        /// completes first, then the data in the provided buffer may have been
+        /// partially written. However, it is guaranteed that the provided
+        /// buffer has been [advanced] by the amount of bytes that have been
+        /// partially written.
+        ///
         /// # Examples
         ///
         /// [`File`] implements [`AsyncWrite`] and [`Cursor`]`<&[u8]>` implements [`Buf`]:
@@ -261,6 +293,7 @@ cfg_io_util! {
         /// [`File`]: crate::fs::File
         /// [`Buf`]: bytes::Buf
         /// [`Cursor`]: std::io::Cursor
+        /// [advanced]: bytes::Buf::advance
         ///
         /// ```no_run
         /// use tokio::io::{self, AsyncWriteExt};
@@ -300,6 +333,14 @@ cfg_io_util! {
         /// has been successfully written or such an error occurs. The first
         /// error generated from this method will be returned.
         ///
+        /// # Cancel safety
+        ///
+        /// This method is not cancellation safe. If it is used as the event
+        /// in a [`tokio::select!`](crate::select) statement and some other
+        /// branch completes first, then the provided buffer may have been
+        /// partially written, but future calls to `write_all` will start over
+        /// from the beginning of the buffer.
+        ///
         /// # Errors
         ///
         /// This function will return the first error that [`write`] returns.
@@ -621,8 +662,8 @@ cfg_io_util! {
             /// async fn main() -> io::Result<()> {
             ///     let mut writer = Vec::new();
             ///
-            ///     writer.write_i64(i64::min_value()).await?;
-            ///     writer.write_i64(i64::max_value()).await?;
+            ///     writer.write_i64(i64::MIN).await?;
+            ///     writer.write_i64(i64::MAX).await?;
             ///
             ///     assert_eq!(writer, b"\x80\x00\x00\x00\x00\x00\x00\x00\x7f\xff\xff\xff\xff\xff\xff\xff");
             ///     Ok(())
@@ -699,7 +740,7 @@ cfg_io_util! {
             /// async fn main() -> io::Result<()> {
             ///     let mut writer = Vec::new();
             ///
-            ///     writer.write_i128(i128::min_value()).await?;
+            ///     writer.write_i128(i128::MIN).await?;
             ///
             ///     assert_eq!(writer, vec![
             ///         0x80, 0, 0, 0, 0, 0, 0, 0,
@@ -710,6 +751,81 @@ cfg_io_util! {
             /// ```
             fn write_i128(&mut self, n: i128) -> WriteI128;
 
+            /// Writes an 32-bit floating point type in big-endian order to the
+            /// underlying writer.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn write_f32(&mut self, n: f32) -> io::Result<()>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered writer to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncWriteExt::write_all`].
+            ///
+            /// [`AsyncWriteExt::write_all`]: AsyncWriteExt::write_all
+            ///
+            /// # Examples
+            ///
+            /// Write 32-bit floating point type to a `AsyncWrite`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncWriteExt};
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut writer = Vec::new();
+            ///
+            ///     writer.write_f32(f32::MIN).await?;
+            ///
+            ///     assert_eq!(writer, vec![0xff, 0x7f, 0xff, 0xff]);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn write_f32(&mut self, n: f32) -> WriteF32;
+
+            /// Writes an 64-bit floating point type in big-endian order to the
+            /// underlying writer.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn write_f64(&mut self, n: f64) -> io::Result<()>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered writer to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncWriteExt::write_all`].
+            ///
+            /// [`AsyncWriteExt::write_all`]: AsyncWriteExt::write_all
+            ///
+            /// # Examples
+            ///
+            /// Write 64-bit floating point type to a `AsyncWrite`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncWriteExt};
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut writer = Vec::new();
+            ///
+            ///     writer.write_f64(f64::MIN).await?;
+            ///
+            ///     assert_eq!(writer, vec![
+            ///         0xff, 0xef, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
+            ///     ]);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn write_f64(&mut self, n: f64) -> WriteF64;
 
             /// Writes an unsigned 16-bit integer in little-endian order to the
             /// underlying writer.
@@ -930,8 +1046,8 @@ cfg_io_util! {
             /// async fn main() -> io::Result<()> {
             ///     let mut writer = Vec::new();
             ///
-            ///     writer.write_i64_le(i64::min_value()).await?;
-            ///     writer.write_i64_le(i64::max_value()).await?;
+            ///     writer.write_i64_le(i64::MIN).await?;
+            ///     writer.write_i64_le(i64::MAX).await?;
             ///
             ///     assert_eq!(writer, b"\x00\x00\x00\x00\x00\x00\x00\x80\xff\xff\xff\xff\xff\xff\xff\x7f");
             ///     Ok(())
@@ -1008,7 +1124,7 @@ cfg_io_util! {
             /// async fn main() -> io::Result<()> {
             ///     let mut writer = Vec::new();
             ///
-            ///     writer.write_i128_le(i128::min_value()).await?;
+            ///     writer.write_i128_le(i128::MIN).await?;
             ///
             ///     assert_eq!(writer, vec![
             ///          0, 0, 0, 0, 0, 0, 0,
@@ -1018,6 +1134,82 @@ cfg_io_util! {
             /// }
             /// ```
             fn write_i128_le(&mut self, n: i128) -> WriteI128Le;
+
+            /// Writes an 32-bit floating point type in little-endian order to the
+            /// underlying writer.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn write_f32_le(&mut self, n: f32) -> io::Result<()>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered writer to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncWriteExt::write_all`].
+            ///
+            /// [`AsyncWriteExt::write_all`]: AsyncWriteExt::write_all
+            ///
+            /// # Examples
+            ///
+            /// Write 32-bit floating point type to a `AsyncWrite`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncWriteExt};
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut writer = Vec::new();
+            ///
+            ///     writer.write_f32_le(f32::MIN).await?;
+            ///
+            ///     assert_eq!(writer, vec![0xff, 0xff, 0x7f, 0xff]);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn write_f32_le(&mut self, n: f32) -> WriteF32Le;
+
+            /// Writes an 64-bit floating point type in little-endian order to the
+            /// underlying writer.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn write_f64_le(&mut self, n: f64) -> io::Result<()>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered writer to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncWriteExt::write_all`].
+            ///
+            /// [`AsyncWriteExt::write_all`]: AsyncWriteExt::write_all
+            ///
+            /// # Examples
+            ///
+            /// Write 64-bit floating point type to a `AsyncWrite`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncWriteExt};
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut writer = Vec::new();
+            ///
+            ///     writer.write_f64_le(f64::MIN).await?;
+            ///
+            ///     assert_eq!(writer, vec![
+            ///         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0xff
+            ///     ]);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn write_f64_le(&mut self, n: f64) -> WriteF64Le;
         }
 
         /// Flushes this output stream, ensuring that all intermediately buffered

tokio/src/io/util/buf_reader.rs

@@ -2,7 +2,7 @@ use crate::io::util::DEFAULT_BUF_SIZE;
 use crate::io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, ReadBuf};
 
 use pin_project_lite::pin_project;
-use std::io::{self, SeekFrom};
+use std::io::{self, IoSlice, SeekFrom};
 use std::pin::Pin;
 use std::task::{Context, Poll};
 use std::{cmp, fmt, mem};
@@ -198,7 +198,7 @@ impl<R: AsyncRead + AsyncSeek> AsyncSeek for BufReader<R> {
                 // it should be safe to assume that remainder fits within an i64 as the alternative
                 // means we managed to allocate 8 exbibytes and that's absurd.
                 // But it's not out of the realm of possibility for some weird underlying reader to
-                // support seeking by i64::min_value() so we need to handle underflow when subtracting
+                // support seeking by i64::MIN so we need to handle underflow when subtracting
                 // remainder.
                 if let Some(offset) = n.checked_sub(remainder) {
                     self.as_mut()
@@ -268,6 +268,18 @@ impl<R: AsyncRead + AsyncWrite> AsyncWrite for BufReader<R> {
         self.get_pin_mut().poll_write(cx, buf)
     }
 
+    fn poll_write_vectored(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[IoSlice<'_>],
+    ) -> Poll<io::Result<usize>> {
+        self.get_pin_mut().poll_write_vectored(cx, bufs)
+    }
+
+    fn is_write_vectored(&self) -> bool {
+        self.get_ref().is_write_vectored()
+    }
+
     fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
         self.get_pin_mut().poll_flush(cx)
     }

tokio/src/io/util/buf_stream.rs

@@ -1,8 +1,8 @@
 use crate::io::util::{BufReader, BufWriter};
-use crate::io::{AsyncBufRead, AsyncRead, AsyncWrite, ReadBuf};
+use crate::io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, ReadBuf};
 
 use pin_project_lite::pin_project;
-use std::io;
+use std::io::{self, IoSlice, SeekFrom};
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
@@ -127,6 +127,18 @@ impl<RW: AsyncRead + AsyncWrite> AsyncWrite for BufStream<RW> {
         self.project().inner.poll_write(cx, buf)
     }
 
+    fn poll_write_vectored(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[IoSlice<'_>],
+    ) -> Poll<io::Result<usize>> {
+        self.project().inner.poll_write_vectored(cx, bufs)
+    }
+
+    fn is_write_vectored(&self) -> bool {
+        self.inner.is_write_vectored()
+    }
+
     fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
         self.project().inner.poll_flush(cx)
     }
@@ -146,6 +158,34 @@ impl<RW: AsyncRead + AsyncWrite> AsyncRead for BufStream<RW> {
     }
 }
 
+/// Seek to an offset, in bytes, in the underlying stream.
+///
+/// The position used for seeking with `SeekFrom::Current(_)` is the
+/// position the underlying stream would be at if the `BufStream` had no
+/// internal buffer.
+///
+/// Seeking always discards the internal buffer, even if the seek position
+/// would otherwise fall within it. This guarantees that calling
+/// `.into_inner()` immediately after a seek yields the underlying reader
+/// at the same position.
+///
+/// See [`AsyncSeek`] for more details.
+///
+/// Note: In the edge case where you're seeking with `SeekFrom::Current(n)`
+/// where `n` minus the internal buffer length overflows an `i64`, two
+/// seeks will be performed instead of one. If the second seek returns
+/// `Err`, the underlying reader will be left at the same position it would
+/// have if you called `seek` with `SeekFrom::Current(0)`.
+impl<RW: AsyncRead + AsyncWrite + AsyncSeek> AsyncSeek for BufStream<RW> {
+    fn start_seek(self: Pin<&mut Self>, position: SeekFrom) -> io::Result<()> {
+        self.project().inner.start_seek(position)
+    }
+
+    fn poll_complete(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<u64>> {
+        self.project().inner.poll_complete(cx)
+    }
+}
+
 impl<RW: AsyncRead + AsyncWrite> AsyncBufRead for BufStream<RW> {
     fn poll_fill_buf(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<&[u8]>> {
         self.project().inner.poll_fill_buf(cx)

tokio/src/io/util/buf_writer.rs

@@ -3,7 +3,7 @@ use crate::io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, ReadBuf};
 
 use pin_project_lite::pin_project;
 use std::fmt;
-use std::io::{self, SeekFrom, Write};
+use std::io::{self, IoSlice, SeekFrom, Write};
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
@@ -133,6 +133,72 @@ impl<W: AsyncWrite> AsyncWrite for BufWriter<W> {
         }
     }
 
+    fn poll_write_vectored(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        mut bufs: &[IoSlice<'_>],
+    ) -> Poll<io::Result<usize>> {
+        if self.inner.is_write_vectored() {
+            let total_len = bufs
+                .iter()
+                .fold(0usize, |acc, b| acc.saturating_add(b.len()));
+            if total_len > self.buf.capacity() - self.buf.len() {
+                ready!(self.as_mut().flush_buf(cx))?;
+            }
+            let me = self.as_mut().project();
+            if total_len >= me.buf.capacity() {
+                // It's more efficient to pass the slices directly to the
+                // underlying writer than to buffer them.
+                // The case when the total_len calculation saturates at
+                // usize::MAX is also handled here.
+                me.inner.poll_write_vectored(cx, bufs)
+            } else {
+                bufs.iter().for_each(|b| me.buf.extend_from_slice(b));
+                Poll::Ready(Ok(total_len))
+            }
+        } else {
+            // Remove empty buffers at the beginning of bufs.
+            while bufs.first().map(|buf| buf.len()) == Some(0) {
+                bufs = &bufs[1..];
+            }
+            if bufs.is_empty() {
+                return Poll::Ready(Ok(0));
+            }
+            // Flush if the first buffer doesn't fit.
+            let first_len = bufs[0].len();
+            if first_len > self.buf.capacity() - self.buf.len() {
+                ready!(self.as_mut().flush_buf(cx))?;
+                debug_assert!(self.buf.is_empty());
+            }
+            let me = self.as_mut().project();
+            if first_len >= me.buf.capacity() {
+                // The slice is at least as large as the buffering capacity,
+                // so it's better to write it directly, bypassing the buffer.
+                debug_assert!(me.buf.is_empty());
+                return me.inner.poll_write(cx, &bufs[0]);
+            } else {
+                me.buf.extend_from_slice(&bufs[0]);
+                bufs = &bufs[1..];
+            }
+            let mut total_written = first_len;
+            debug_assert!(total_written != 0);
+            // Append the buffers that fit in the internal buffer.
+            for buf in bufs {
+                if buf.len() > me.buf.capacity() - me.buf.len() {
+                    break;
+                } else {
+                    me.buf.extend_from_slice(buf);
+                    total_written += buf.len();
+                }
+            }
+            Poll::Ready(Ok(total_written))
+        }
+    }
+
+    fn is_write_vectored(&self) -> bool {
+        true
+    }
+
     fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
         ready!(self.as_mut().flush_buf(cx))?;
         self.get_pin_mut().poll_flush(cx)

tokio/src/io/util/copy.rs

@@ -8,6 +8,7 @@ use std::task::{Context, Poll};
 #[derive(Debug)]
 pub(super) struct CopyBuffer {
     read_done: bool,
+    need_flush: bool,
     pos: usize,
     cap: usize,
     amt: u64,
@@ -18,6 +19,7 @@ impl CopyBuffer {
     pub(super) fn new() -> Self {
         Self {
             read_done: false,
+            need_flush: false,
             pos: 0,
             cap: 0,
             amt: 0,
@@ -41,7 +43,22 @@ impl CopyBuffer {
             if self.pos == self.cap && !self.read_done {
                 let me = &mut *self;
                 let mut buf = ReadBuf::new(&mut me.buf);
-                ready!(reader.as_mut().poll_read(cx, &mut buf))?;
+
+                match reader.as_mut().poll_read(cx, &mut buf) {
+                    Poll::Ready(Ok(_)) => (),
+                    Poll::Ready(Err(err)) => return Poll::Ready(Err(err)),
+                    Poll::Pending => {
+                        // Try flushing when the reader has no progress to avoid deadlock
+                        // when the reader depends on buffered writer.
+                        if self.need_flush {
+                            ready!(writer.as_mut().poll_flush(cx))?;
+                            self.need_flush = false;
+                        }
+
+                        return Poll::Pending;
+                    }
+                }
+
                 let n = buf.filled().len();
                 if n == 0 {
                     self.read_done = true;
@@ -63,6 +80,7 @@ impl CopyBuffer {
                 } else {
                     self.pos += i;
                     self.amt += i as u64;
+                    self.need_flush = true;
                 }
             }
 

tokio/src/io/util/fill_buf.rs

@@ -0,0 +1,52 @@
+use crate::io::AsyncBufRead;
+
+use pin_project_lite::pin_project;
+use std::future::Future;
+use std::io;
+use std::marker::PhantomPinned;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+pin_project! {
+    /// Future for the [`fill_buf`](crate::io::AsyncBufReadExt::fill_buf) method.
+    #[derive(Debug)]
+    #[must_use = "futures do nothing unless you `.await` or poll them"]
+    pub struct FillBuf<'a, R: ?Sized> {
+        reader: Option<&'a mut R>,
+        #[pin]
+        _pin: PhantomPinned,
+    }
+}
+
+pub(crate) fn fill_buf<R>(reader: &mut R) -> FillBuf<'_, R>
+where
+    R: AsyncBufRead + ?Sized + Unpin,
+{
+    FillBuf {
+        reader: Some(reader),
+        _pin: PhantomPinned,
+    }
+}
+
+impl<'a, R: AsyncBufRead + ?Sized + Unpin> Future for FillBuf<'a, R> {
+    type Output = io::Result<&'a [u8]>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let me = self.project();
+
+        // Due to a limitation in the borrow-checker, we cannot return the value
+        // directly on Ready. Once Rust starts using the polonius borrow checker,
+        // this can be simplified.
+        let reader = me.reader.take().expect("Polled after completion.");
+        match Pin::new(&mut *reader).poll_fill_buf(cx) {
+            Poll::Ready(_) => match Pin::new(reader).poll_fill_buf(cx) {
+                Poll::Ready(slice) => Poll::Ready(slice),
+                Poll::Pending => panic!("poll_fill_buf returned Pending while having data"),
+            },
+            Poll::Pending => {
+                *me.reader = Some(reader);
+                Poll::Pending
+            }
+        }
+    }
+}

tokio/src/io/util/lines.rs

@@ -47,6 +47,10 @@ where
 {
     /// Returns the next line in the stream.
     ///
+    /// # Cancel safety
+    ///
+    /// This method is cancellation safe.
+    ///
     /// # Examples
     ///
     /// ```
@@ -102,11 +106,9 @@ where
     ///
     /// When the method returns `Poll::Pending`, the `Waker` in the provided
     /// `Context` is scheduled to receive a wakeup when more bytes become
-    /// available on the underlying IO resource.
-    ///
-    /// Note that on multiple calls to `poll_next_line`, only the `Waker` from
-    /// the `Context` passed to the most recent call is scheduled to receive a
-    /// wakeup.
+    /// available on the underlying IO resource.  Note that on multiple calls to
+    /// `poll_next_line`, only the `Waker` from the `Context` passed to the most
+    /// recent call is scheduled to receive a wakeup.
     pub fn poll_next_line(
         self: Pin<&mut Self>,
         cx: &mut Context<'_>,

tokio/src/io/util/mod.rs

@@ -49,6 +49,7 @@ cfg_io_util! {
     mod read_exact;
     mod read_int;
     mod read_line;
+    mod fill_buf;
 
     mod read_to_end;
     mod vec_with_initialized;

tokio/src/io/util/read_int.rs

@@ -142,6 +142,9 @@ reader!(ReadI32, i32, get_i32);
 reader!(ReadI64, i64, get_i64);
 reader!(ReadI128, i128, get_i128);
 
+reader!(ReadF32, f32, get_f32);
+reader!(ReadF64, f64, get_f64);
+
 reader!(ReadU16Le, u16, get_u16_le);
 reader!(ReadU32Le, u32, get_u32_le);
 reader!(ReadU64Le, u64, get_u64_le);
@@ -151,3 +154,6 @@ reader!(ReadI16Le, i16, get_i16_le);
 reader!(ReadI32Le, i32, get_i32_le);
 reader!(ReadI64Le, i64, get_i64_le);
 reader!(ReadI128Le, i128, get_i128_le);
+
+reader!(ReadF32Le, f32, get_f32_le);
+reader!(ReadF64Le, f64, get_f64_le);

tokio/src/io/util/read_until.rs

@@ -10,12 +10,12 @@ use std::task::{Context, Poll};
 
 pin_project! {
     /// Future for the [`read_until`](crate::io::AsyncBufReadExt::read_until) method.
-    /// The delimeter is included in the resulting vector.
+    /// The delimiter is included in the resulting vector.
     #[derive(Debug)]
     #[must_use = "futures do nothing unless you `.await` or poll them"]
     pub struct ReadUntil<'a, R: ?Sized> {
         reader: &'a mut R,
-        delimeter: u8,
+        delimiter: u8,
         buf: &'a mut Vec<u8>,
         // The number of bytes appended to buf. This can be less than buf.len() if
         // the buffer was not empty when the operation was started.
@@ -28,7 +28,7 @@ pin_project! {
 
 pub(crate) fn read_until<'a, R>(
     reader: &'a mut R,
-    delimeter: u8,
+    delimiter: u8,
     buf: &'a mut Vec<u8>,
 ) -> ReadUntil<'a, R>
 where
@@ -36,7 +36,7 @@ where
 {
     ReadUntil {
         reader,
-        delimeter,
+        delimiter,
         buf,
         read: 0,
         _pin: PhantomPinned,
@@ -46,14 +46,14 @@ where
 pub(super) fn read_until_internal<R: AsyncBufRead + ?Sized>(
     mut reader: Pin<&mut R>,
     cx: &mut Context<'_>,
-    delimeter: u8,
+    delimiter: u8,
     buf: &mut Vec<u8>,
     read: &mut usize,
 ) -> Poll<io::Result<usize>> {
     loop {
         let (done, used) = {
             let available = ready!(reader.as_mut().poll_fill_buf(cx))?;
-            if let Some(i) = memchr::memchr(delimeter, available) {
+            if let Some(i) = memchr::memchr(delimiter, available) {
                 buf.extend_from_slice(&available[..=i]);
                 (true, i + 1)
             } else {
@@ -74,6 +74,6 @@ impl<R: AsyncBufRead + ?Sized + Unpin> Future for ReadUntil<'_, R> {
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         let me = self.project();
-        read_until_internal(Pin::new(*me.reader), cx, *me.delimeter, me.buf, me.read)
+        read_until_internal(Pin::new(*me.reader), cx, *me.delimiter, me.buf, me.read)
     }
 }

tokio/src/io/util/split.rs

@@ -95,7 +95,7 @@ where
         let n = ready!(read_until_internal(
             me.reader, cx, *me.delim, me.buf, me.read,
         ))?;
-        // read_until_internal resets me.read to zero once it finds the delimeter
+        // read_until_internal resets me.read to zero once it finds the delimiter
         debug_assert_eq!(*me.read, 0);
 
         if n == 0 && me.buf.is_empty() {

tokio/src/io/util/write_int.rs

@@ -135,6 +135,9 @@ writer!(WriteI32, i32, put_i32);
 writer!(WriteI64, i64, put_i64);
 writer!(WriteI128, i128, put_i128);
 
+writer!(WriteF32, f32, put_f32);
+writer!(WriteF64, f64, put_f64);
+
 writer!(WriteU16Le, u16, put_u16_le);
 writer!(WriteU32Le, u32, put_u32_le);
 writer!(WriteU64Le, u64, put_u64_le);
@@ -144,3 +147,6 @@ writer!(WriteI16Le, i16, put_i16_le);
 writer!(WriteI32Le, i32, put_i32_le);
 writer!(WriteI64Le, i64, put_i64_le);
 writer!(WriteI128Le, i128, put_i128_le);
+
+writer!(WriteF32Le, f32, put_f32_le);
+writer!(WriteF64Le, f64, put_f64_le);

tokio/src/lib.rs

@@ -9,7 +9,8 @@
     rust_2018_idioms,
     unreachable_pub
 )]
-#![cfg_attr(docsrs, deny(broken_intra_doc_links))]
+#![deny(unused_must_use)]
+#![cfg_attr(docsrs, deny(rustdoc::broken_intra_doc_links))]
 #![doc(test(
     no_crate_inject,
     attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))
@@ -442,6 +443,28 @@ mod util;
 /// ```
 pub mod stream {}
 
+// local re-exports of platform specific things, allowing for decent
+// documentation to be shimmed in on docs.rs
+
+#[cfg(docsrs)]
+pub mod doc;
+
+#[cfg(docsrs)]
+#[allow(unused)]
+pub(crate) use self::doc::os;
+
+#[cfg(not(docsrs))]
+#[allow(unused)]
+pub(crate) use std::os;
+
+#[cfg(docsrs)]
+#[allow(unused)]
+pub(crate) use self::doc::winapi;
+
+#[cfg(all(not(docsrs), windows, feature = "net"))]
+#[allow(unused)]
+pub(crate) use ::winapi;
+
 cfg_macros! {
     /// Implementation detail of the `select!` macro. This macro is **not**
     /// intended to be used as part of the public API and is permitted to
@@ -453,15 +476,20 @@ cfg_macros! {
         #[cfg(feature = "rt-multi-thread")]
         #[cfg(not(test))] // Work around for rust-lang/rust#62127
         #[cfg_attr(docsrs, doc(cfg(feature = "macros")))]
+        #[doc(inline)]
         pub use tokio_macros::main;
 
         #[cfg(feature = "rt-multi-thread")]
         #[cfg_attr(docsrs, doc(cfg(feature = "macros")))]
+        #[doc(inline)]
         pub use tokio_macros::test;
 
         cfg_not_rt_multi_thread! {
             #[cfg(not(test))] // Work around for rust-lang/rust#62127
+            #[doc(inline)]
             pub use tokio_macros::main_rt as main;
+
+            #[doc(inline)]
             pub use tokio_macros::test_rt as test;
         }
     }
@@ -469,7 +497,10 @@ cfg_macros! {
     // Always fail if rt is not enabled.
     cfg_not_rt! {
         #[cfg(not(test))]
+        #[doc(inline)]
         pub use tokio_macros::main_fail as main;
+
+        #[doc(inline)]
         pub use tokio_macros::test_fail as test;
     }
 }

tokio/src/loom/std/atomic_u64.rs

@@ -2,21 +2,17 @@
 //! re-export of `AtomicU64`. On 32 bit platforms, this is implemented using a
 //! `Mutex`.
 
-pub(crate) use self::imp::AtomicU64;
-
 // `AtomicU64` can only be used on targets with `target_has_atomic` is 64 or greater.
 // Once `cfg_target_has_atomic` feature is stable, we can replace it with
 // `#[cfg(target_has_atomic = "64")]`.
 // Refs: https://github.com/rust-lang/rust/tree/master/src/librustc_target
-#[cfg(not(any(target_arch = "arm", target_arch = "mips", target_arch = "powerpc")))]
-mod imp {
+cfg_has_atomic_u64! {
     pub(crate) use std::sync::atomic::AtomicU64;
 }
 
-#[cfg(any(target_arch = "arm", target_arch = "mips", target_arch = "powerpc"))]
-mod imp {
+cfg_not_has_atomic_u64! {
+    use crate::loom::sync::Mutex;
     use std::sync::atomic::Ordering;
-    use std::sync::Mutex;
 
     #[derive(Debug)]
     pub(crate) struct AtomicU64 {
@@ -31,15 +27,15 @@ mod imp {
         }
 
         pub(crate) fn load(&self, _: Ordering) -> u64 {
-            *self.inner.lock().unwrap()
+            *self.inner.lock()
         }
 
         pub(crate) fn store(&self, val: u64, _: Ordering) {
-            *self.inner.lock().unwrap() = val;
+            *self.inner.lock() = val;
         }
 
         pub(crate) fn fetch_or(&self, val: u64, _: Ordering) -> u64 {
-            let mut lock = self.inner.lock().unwrap();
+            let mut lock = self.inner.lock();
             let prev = *lock;
             *lock = prev | val;
             prev
@@ -52,7 +48,7 @@ mod imp {
             _success: Ordering,
             _failure: Ordering,
         ) -> Result<u64, u64> {
-            let mut lock = self.inner.lock().unwrap();
+            let mut lock = self.inner.lock();
 
             if *lock == current {
                 *lock = new;

tokio/src/macros/cfg.rs

@@ -157,7 +157,6 @@ macro_rules! cfg_macros {
         $(
             #[cfg(feature = "macros")]
             #[cfg_attr(docsrs, doc(cfg(feature = "macros")))]
-            #[doc(inline)]
             $item
         )*
     }
@@ -183,6 +182,16 @@ macro_rules! cfg_net_unix {
     }
 }
 
+macro_rules! cfg_net_windows {
+    ($($item:item)*) => {
+        $(
+            #[cfg(all(any(all(doc, docsrs), windows), feature = "net"))]
+            #[cfg_attr(docsrs, doc(cfg(all(windows, feature = "net"))))]
+            $item
+        )*
+    }
+}
+
 macro_rules! cfg_process {
     ($($item:item)*) => {
         $(
@@ -375,3 +384,29 @@ macro_rules! cfg_not_coop {
         )*
     }
 }
+
+macro_rules! cfg_has_atomic_u64 {
+    ($($item:item)*) => {
+        $(
+            #[cfg(not(any(
+                    target_arch = "arm",
+                    target_arch = "mips",
+                    target_arch = "powerpc"
+                    )))]
+            $item
+        )*
+    }
+}
+
+macro_rules! cfg_not_has_atomic_u64 {
+    ($($item:item)*) => {
+        $(
+            #[cfg(any(
+                    target_arch = "arm",
+                    target_arch = "mips",
+                    target_arch = "powerpc"
+                    ))]
+            $item
+        )*
+    }
+}

tokio/src/macros/select.rs

@@ -23,10 +23,10 @@
 /// returns the result of evaluating the completed branch's `<handler>`
 /// expression.
 ///
-/// Additionally, each branch may include an optional `if` precondition. This
-/// precondition is evaluated **before** the `<async expression>`. If the
-/// precondition returns `false`, the branch is entirely disabled. This
-/// capability is useful when using `select!` within a loop.
+/// Additionally, each branch may include an optional `if` precondition. If the
+/// precondition returns `false`, then the branch is disabled. The provided
+/// `<async expression>` is still evaluated but the resulting future is never
+/// polled. This capability is useful when using `select!` within a loop.
 ///
 /// The complete lifecycle of a `select!` expression is as follows:
 ///
@@ -42,12 +42,10 @@
 ///    to the provided `<pattern>`, if the pattern matches, evaluate `<handler>`
 ///    and return. If the pattern **does not** match, disable the current branch
 ///    and for the remainder of the current call to `select!`. Continue from step 3.
-/// 5. If **all** branches are disabled, evaluate the `else` expression. If none
-///    is provided, panic.
+/// 5. If **all** branches are disabled, evaluate the `else` expression. If no
+///    else branch is provided, panic.
 ///
-/// # Notes
-///
-/// ### Runtime characteristics
+/// # Runtime characteristics
 ///
 /// By running all async expressions on the current task, the expressions are
 /// able to run **concurrently** but not in **parallel**. This means all
@@ -58,76 +56,7 @@
 ///
 /// [`tokio::spawn`]: crate::spawn
 ///
-/// ### Avoid racy `if` preconditions
-///
-/// Given that `if` preconditions are used to disable `select!` branches, some
-/// caution must be used to avoid missing values.
-///
-/// For example, here is **incorrect** usage of `sleep` with `if`. The objective
-/// is to repeatedly run an asynchronous task for up to 50 milliseconds.
-/// However, there is a potential for the `sleep` completion to be missed.
-///
-/// ```no_run
-/// use tokio::time::{self, Duration};
-///
-/// async fn some_async_work() {
-///     // do work
-/// }
-///
-/// #[tokio::main]
-/// async fn main() {
-///     let sleep = time::sleep(Duration::from_millis(50));
-///     tokio::pin!(sleep);
-///
-///     while !sleep.is_elapsed() {
-///         tokio::select! {
-///             _ = &mut sleep, if !sleep.is_elapsed() => {
-///                 println!("operation timed out");
-///             }
-///             _ = some_async_work() => {
-///                 println!("operation completed");
-///             }
-///         }
-///     }
-/// }
-/// ```
-///
-/// In the above example, `sleep.is_elapsed()` may return `true` even if
-/// `sleep.poll()` never returned `Ready`. This opens up a potential race
-/// condition where `sleep` expires between the `while !sleep.is_elapsed()`
-/// check and the call to `select!` resulting in the `some_async_work()` call to
-/// run uninterrupted despite the sleep having elapsed.
-///
-/// One way to write the above example without the race would be:
-///
-/// ```
-/// use tokio::time::{self, Duration};
-///
-/// async fn some_async_work() {
-/// # time::sleep(Duration::from_millis(10)).await;
-///     // do work
-/// }
-///
-/// #[tokio::main]
-/// async fn main() {
-///     let sleep = time::sleep(Duration::from_millis(50));
-///     tokio::pin!(sleep);
-///
-///     loop {
-///         tokio::select! {
-///             _ = &mut sleep => {
-///                 println!("operation timed out");
-///                 break;
-///             }
-///             _ = some_async_work() => {
-///                 println!("operation completed");
-///             }
-///         }
-///     }
-/// }
-/// ```
-///
-/// ### Fairness
+/// # Fairness
 ///
 /// By default, `select!` randomly picks a branch to check first. This provides
 /// some level of fairness when calling `select!` in a loop with branches that
@@ -151,10 +80,60 @@
 ///
 /// # Panics
 ///
-/// `select!` panics if all branches are disabled **and** there is no provided
-/// `else` branch. A branch is disabled when the provided `if` precondition
-/// returns `false` **or** when the pattern does not match the result of `<async
-/// expression>`.
+/// The `select!` macro panics if all branches are disabled **and** there is no
+/// provided `else` branch. A branch is disabled when the provided `if`
+/// precondition returns `false` **or** when the pattern does not match the
+/// result of `<async expression>`.
+///
+/// # Cancellation safety
+///
+/// When using `select!` in a loop to receive messages from multiple sources,
+/// you should make sure that the receive call is cancellation safe to avoid
+/// losing messages. This section goes through various common methods and
+/// describes whether they are cancel safe.  The lists in this section are not
+/// exhaustive.
+///
+/// The following methods are cancellation safe:
+///
+///  * [`tokio::sync::mpsc::Receiver::recv`](crate::sync::mpsc::Receiver::recv)
+///  * [`tokio::sync::mpsc::UnboundedReceiver::recv`](crate::sync::mpsc::UnboundedReceiver::recv)
+///  * [`tokio::sync::broadcast::Receiver::recv`](crate::sync::broadcast::Receiver::recv)
+///  * [`tokio::sync::watch::Receiver::changed`](crate::sync::watch::Receiver::changed)
+///  * [`tokio::net::TcpListener::accept`](crate::net::TcpListener::accept)
+///  * [`tokio::net::UnixListener::accept`](crate::net::UnixListener::accept)
+///  * [`tokio::io::AsyncReadExt::read`](crate::io::AsyncReadExt::read) on any `AsyncRead`
+///  * [`tokio::io::AsyncReadExt::read_buf`](crate::io::AsyncReadExt::read_buf) on any `AsyncRead`
+///  * [`tokio::io::AsyncWriteExt::write`](crate::io::AsyncWriteExt::write) on any `AsyncWrite`
+///  * [`tokio::io::AsyncWriteExt::write_buf`](crate::io::AsyncWriteExt::write_buf) on any `AsyncWrite`
+///  * [`tokio_stream::StreamExt::next`](https://docs.rs/tokio-stream/0.1/tokio_stream/trait.StreamExt.html#method.next) on any `Stream`
+///  * [`futures::stream::StreamExt::next`](https://docs.rs/futures/0.3/futures/stream/trait.StreamExt.html#method.next) on any `Stream`
+///
+/// The following methods are not cancellation safe and can lead to loss of data:
+///
+///  * [`tokio::io::AsyncReadExt::read_exact`](crate::io::AsyncReadExt::read_exact)
+///  * [`tokio::io::AsyncReadExt::read_to_end`](crate::io::AsyncReadExt::read_to_end)
+///  * [`tokio::io::AsyncReadExt::read_to_string`](crate::io::AsyncReadExt::read_to_string)
+///  * [`tokio::io::AsyncWriteExt::write_all`](crate::io::AsyncWriteExt::write_all)
+///
+/// The following methods are not cancellation safe because they use a queue for
+/// fairness and cancellation makes you lose your place in the queue:
+///
+///  * [`tokio::sync::Mutex::lock`](crate::sync::Mutex::lock)
+///  * [`tokio::sync::RwLock::read`](crate::sync::RwLock::read)
+///  * [`tokio::sync::RwLock::write`](crate::sync::RwLock::write)
+///  * [`tokio::sync::Semaphore::acquire`](crate::sync::Semaphore::acquire)
+///  * [`tokio::sync::Notify::notified`](crate::sync::Notify::notified)
+///
+/// To determine whether your own methods are cancellation safe, look for the
+/// location of uses of `.await`. This is because when an asynchronous method is
+/// cancelled, that always happens at an `.await`. If your function behaves
+/// correctly even if it is restarted while waiting at an `.await`, then it is
+/// cancellation safe.
+///
+/// Be aware that cancelling something that is not cancellation safe is not
+/// necessarily wrong. For example, if you are cancelling a task because the
+/// application is shutting down, then you probably don't care that partially
+/// read data is lost.
 ///
 /// # Examples
 ///
@@ -310,7 +289,7 @@
 ///     loop {
 ///         tokio::select! {
 ///             // If you run this example without `biased;`, the polling order is
-///             // psuedo-random, and the assertions on the value of count will
+///             // pseudo-random, and the assertions on the value of count will
 ///             // (probably) fail.
 ///             biased;
 ///
@@ -338,6 +317,77 @@
 ///     }
 /// }
 /// ```
+///
+/// ## Avoid racy `if` preconditions
+///
+/// Given that `if` preconditions are used to disable `select!` branches, some
+/// caution must be used to avoid missing values.
+///
+/// For example, here is **incorrect** usage of `sleep` with `if`. The objective
+/// is to repeatedly run an asynchronous task for up to 50 milliseconds.
+/// However, there is a potential for the `sleep` completion to be missed.
+///
+/// ```no_run,should_panic
+/// use tokio::time::{self, Duration};
+///
+/// async fn some_async_work() {
+///     // do work
+/// }
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let sleep = time::sleep(Duration::from_millis(50));
+///     tokio::pin!(sleep);
+///
+///     while !sleep.is_elapsed() {
+///         tokio::select! {
+///             _ = &mut sleep, if !sleep.is_elapsed() => {
+///                 println!("operation timed out");
+///             }
+///             _ = some_async_work() => {
+///                 println!("operation completed");
+///             }
+///         }
+///     }
+///
+///     panic!("This example shows how not to do it!");
+/// }
+/// ```
+///
+/// In the above example, `sleep.is_elapsed()` may return `true` even if
+/// `sleep.poll()` never returned `Ready`. This opens up a potential race
+/// condition where `sleep` expires between the `while !sleep.is_elapsed()`
+/// check and the call to `select!` resulting in the `some_async_work()` call to
+/// run uninterrupted despite the sleep having elapsed.
+///
+/// One way to write the above example without the race would be:
+///
+/// ```
+/// use tokio::time::{self, Duration};
+///
+/// async fn some_async_work() {
+/// # time::sleep(Duration::from_millis(10)).await;
+///     // do work
+/// }
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let sleep = time::sleep(Duration::from_millis(50));
+///     tokio::pin!(sleep);
+///
+///     loop {
+///         tokio::select! {
+///             _ = &mut sleep => {
+///                 println!("operation timed out");
+///                 break;
+///             }
+///             _ = some_async_work() => {
+///                 println!("operation completed");
+///             }
+///         }
+///     }
+/// }
+/// ```
 #[macro_export]
 #[cfg_attr(docsrs, doc(cfg(feature = "macros")))]
 macro_rules! select {
@@ -398,7 +448,7 @@ macro_rules! select {
         // set the appropriate bit in `disabled`.
         $(
             if !$c {
-                let mask = 1 << $crate::count!( $($skip)* );
+                let mask: util::Mask = 1 << $crate::count!( $($skip)* );
                 disabled |= mask;
             }
         )*
@@ -417,7 +467,7 @@ macro_rules! select {
                 let mut is_pending = false;
 
                 // Choose a starting index to begin polling the futures at. In
-                // practice, this will either be a psuedo-randomly generrated
+                // practice, this will either be a pseudo-randomly generated
                 // number by default, or the constant 0 if `biased;` is
                 // supplied.
                 let start = $start;

tokio/src/net/mod.rs

@@ -46,3 +46,7 @@ cfg_net_unix! {
     pub use unix::listener::UnixListener;
     pub use unix::stream::UnixStream;
 }
+
+cfg_net_windows! {
+    pub mod windows;
+}

tokio/src/net/tcp/listener.rs

@@ -125,6 +125,13 @@ impl TcpListener {
     /// established, the corresponding [`TcpStream`] and the remote peer's
     /// address will be returned.
     ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. If the method is used as the event in a
+    /// [`tokio::select!`](crate::select) statement and some other branch
+    /// completes first, then it is guaranteed that no new connections were
+    /// accepted by this method.
+    ///
     /// [`TcpStream`]: struct@crate::net::TcpStream
     ///
     /// # Examples

tokio/src/net/tcp/socket.rs

@@ -482,6 +482,48 @@ impl TcpSocket {
         let mio = self.inner.listen(backlog)?;
         TcpListener::new(mio)
     }
+
+    /// Converts a [`std::net::TcpStream`] into a `TcpSocket`. The provided
+    /// socket must not have been connected prior to calling this function. This
+    /// function is typically used together with crates such as [`socket2`] to
+    /// configure socket options that are not available on `TcpSocket`.
+    ///
+    /// [`std::net::TcpStream`]: struct@std::net::TcpStream
+    /// [`socket2`]: https://docs.rs/socket2/
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::net::TcpSocket;
+    /// use socket2::{Domain, Socket, Type};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> std::io::Result<()> {
+    ///     
+    ///     let socket2_socket = Socket::new(Domain::IPV4, Type::STREAM, None)?;
+    ///
+    ///     let socket = TcpSocket::from_std_stream(socket2_socket.into());
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn from_std_stream(std_stream: std::net::TcpStream) -> TcpSocket {
+        #[cfg(unix)]
+        {
+            use std::os::unix::io::{FromRawFd, IntoRawFd};
+
+            let raw_fd = std_stream.into_raw_fd();
+            unsafe { TcpSocket::from_raw_fd(raw_fd) }
+        }
+
+        #[cfg(windows)]
+        {
+            use std::os::windows::io::{FromRawSocket, IntoRawSocket};
+
+            let raw_socket = std_stream.into_raw_socket();
+            unsafe { TcpSocket::from_raw_socket(raw_socket) }
+        }
+    }
 }
 
 impl fmt::Debug for TcpSocket {

tokio/src/net/tcp/split.rs

@@ -30,7 +30,7 @@ pub struct ReadHalf<'a>(&'a TcpStream);
 
 /// Borrowed write half of a [`TcpStream`], created by [`split`].
 ///
-/// Note that in the [`AsyncWrite`] implemenation of this type, [`poll_shutdown`] will
+/// Note that in the [`AsyncWrite`] implementation of this type, [`poll_shutdown`] will
 /// shut down the TCP stream in the write direction.
 ///
 /// Writing to an `WriteHalf` is usually done using the convenience methods found
@@ -57,7 +57,7 @@ impl ReadHalf<'_> {
     /// `Waker` from the `Context` passed to the most recent call is scheduled
     /// to receive a wakeup.
     ///
-    /// See the [`TcpStream::poll_peek`] level documenation for more details.
+    /// See the [`TcpStream::poll_peek`] level documentation for more details.
     ///
     /// # Examples
     ///
@@ -95,7 +95,7 @@ impl ReadHalf<'_> {
     /// connected, without removing that data from the queue. On success,
     /// returns the number of bytes peeked.
     ///
-    /// See the [`TcpStream::peek`] level documenation for more details.
+    /// See the [`TcpStream::peek`] level documentation for more details.
     ///
     /// [`TcpStream::peek`]: TcpStream::peek
     ///

tokio/src/net/tcp/split_owned.rs

@@ -112,7 +112,7 @@ impl OwnedReadHalf {
     /// `Waker` from the `Context` passed to the most recent call is scheduled
     /// to receive a wakeup.
     ///
-    /// See the [`TcpStream::poll_peek`] level documenation for more details.
+    /// See the [`TcpStream::poll_peek`] level documentation for more details.
     ///
     /// # Examples
     ///
@@ -150,7 +150,7 @@ impl OwnedReadHalf {
     /// connected, without removing that data from the queue. On success,
     /// returns the number of bytes peeked.
     ///
-    /// See the [`TcpStream::peek`] level documenation for more details.
+    /// See the [`TcpStream::peek`] level documentation for more details.
     ///
     /// [`TcpStream::peek`]: TcpStream::peek
     ///