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author | Ivan Lozano <ivanlozano@google.com> | 2021-01-26 19:23:00 +0000 |
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committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | 2021-01-26 19:23:00 +0000 |
commit | 2d0ffc896f1a5c38d7dedd746a13492b2ec63284 (patch) | |
tree | 08efa1ccbef1a7ef36c8b30afc594f438eecffd9 | |
parent | a285a7c3d95f91b86b3cb1fbe87e1010156570a6 (diff) | |
parent | c0f49ebcec57f841f20a5a984b0fe3c94c7dd531 (diff) | |
download | tokio-stream-2d0ffc896f1a5c38d7dedd746a13492b2ec63284.tar.gz |
Initial import of tokio_stream am: c0f49ebcec
Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/tokio-stream/+/1558921
MUST ONLY BE SUBMITTED BY AUTOMERGER
Change-Id: I15fea460ae433ca839c7f7631008997d2e0b67ac
51 files changed, 4947 insertions, 0 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md new file mode 100644 index 0000000..bbb7d8c --- /dev/null +++ b/CHANGELOG.md @@ -0,0 +1,22 @@ +# 0.1.2 (January 12, 2021) + +Fixed + + - docs: fix some wrappers missing in documentation (#3378) + +# 0.1.1 (January 4, 2021) + +Added + + - add `Stream` wrappers ([#3343]) + +Fixed + + - move `async-stream` to `dev-dependencies` ([#3366]) + +[#3366]: https://github.com/tokio-rs/tokio/pull/3366 +[#3343]: https://github.com/tokio-rs/tokio/pull/3343 + +# 0.1.0 (December 23, 2020) + + - Initial release diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..443228a --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,55 @@ +# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO +# +# When uploading crates to the registry Cargo will automatically +# "normalize" Cargo.toml files for maximal compatibility +# with all versions of Cargo and also rewrite `path` dependencies +# to registry (e.g., crates.io) dependencies +# +# If you believe there's an error in this file please file an +# issue against the rust-lang/cargo repository. If you're +# editing this file be aware that the upstream Cargo.toml +# will likely look very different (and much more reasonable) + +[package] +edition = "2018" +name = "tokio-stream" +version = "0.1.2" +authors = ["Tokio Contributors <team@tokio.rs>"] +description = "Utilities to work with `Stream` and `tokio`.\n" +homepage = "https://tokio.rs" +documentation = "https://docs.rs/tokio-stream/0.1.2/tokio_stream" +categories = ["asynchronous"] +license = "MIT" +repository = "https://github.com/tokio-rs/tokio" +[package.metadata.docs.rs] +all-features = true +rustdoc-args = ["--cfg", "docsrs"] +[dependencies.futures-core] +version = "0.3.0" + +[dependencies.pin-project-lite] +version = "0.2.0" + +[dependencies.tokio] +version = "1.0" +features = ["sync"] +[dev-dependencies.async-stream] +version = "0.3" + +[dev-dependencies.futures] +version = "0.3" +default-features = false + +[dev-dependencies.proptest] +version = "0.10.0" + +[dev-dependencies.tokio] +version = "1.0" +features = ["full", "test-util"] + +[features] +default = ["time"] +fs = ["tokio/fs"] +io-util = ["tokio/io-util"] +net = ["tokio/net"] +time = ["tokio/time"] diff --git a/Cargo.toml.orig b/Cargo.toml.orig new file mode 100644 index 0000000..d662c38 --- /dev/null +++ b/Cargo.toml.orig @@ -0,0 +1,44 @@ +[package] +name = "tokio-stream" +# When releasing to crates.io: +# - Remove path dependencies +# - Update html_root_url. +# - Update doc url +# - Cargo.toml +# - Update CHANGELOG.md. +# - Create "tokio-stream-0.1.x" git tag. +version = "0.1.2" +edition = "2018" +authors = ["Tokio Contributors <team@tokio.rs>"] +license = "MIT" +repository = "https://github.com/tokio-rs/tokio" +homepage = "https://tokio.rs" +documentation = "https://docs.rs/tokio-stream/0.1.2/tokio_stream" +description = """ +Utilities to work with `Stream` and `tokio`. +""" +categories = ["asynchronous"] + +[features] +default = ["time"] +time = ["tokio/time"] +net = ["tokio/net"] +io-util = ["tokio/io-util"] +fs = ["tokio/fs"] + +[dependencies] +futures-core = { version = "0.3.0" } +pin-project-lite = "0.2.0" +tokio = { version = "1.0", features = ["sync"] } + +[dev-dependencies] +tokio = { version = "1.0", features = ["full", "test-util"] } +tokio-test = { path = "../tokio-test" } +async-stream = "0.3" +futures = { version = "0.3", default-features = false } + +proptest = "0.10.0" + +[package.metadata.docs.rs] +all-features = true +rustdoc-args = ["--cfg", "docsrs"] diff --git a/src/empty.rs b/src/empty.rs new file mode 100644 index 0000000..965dcf5 --- /dev/null +++ b/src/empty.rs @@ -0,0 +1,50 @@ +use crate::Stream; + +use core::marker::PhantomData; +use core::pin::Pin; +use core::task::{Context, Poll}; + +/// Stream for the [`empty`](fn@empty) function. +#[derive(Debug)] +#[must_use = "streams do nothing unless polled"] +pub struct Empty<T>(PhantomData<T>); + +impl<T> Unpin for Empty<T> {} +unsafe impl<T> Send for Empty<T> {} +unsafe impl<T> Sync for Empty<T> {} + +/// Creates a stream that yields nothing. +/// +/// The returned stream is immediately ready and returns `None`. Use +/// [`stream::pending()`](super::pending()) to obtain a stream that is never +/// ready. +/// +/// # Examples +/// +/// Basic usage: +/// +/// ``` +/// use tokio_stream::{self as stream, StreamExt}; +/// +/// #[tokio::main] +/// async fn main() { +/// let mut none = stream::empty::<i32>(); +/// +/// assert_eq!(None, none.next().await); +/// } +/// ``` +pub const fn empty<T>() -> Empty<T> { + Empty(PhantomData) +} + +impl<T> Stream for Empty<T> { + type Item = T; + + fn poll_next(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<T>> { + Poll::Ready(None) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, Some(0)) + } +} diff --git a/src/iter.rs b/src/iter.rs new file mode 100644 index 0000000..128be61 --- /dev/null +++ b/src/iter.rs @@ -0,0 +1,67 @@ +use crate::Stream; + +use core::pin::Pin; +use core::task::{Context, Poll}; + +/// Stream for the [`iter`](fn@iter) function. +#[derive(Debug)] +#[must_use = "streams do nothing unless polled"] +pub struct Iter<I> { + iter: I, + yield_amt: usize, +} + +impl<I> Unpin for Iter<I> {} + +/// Converts an `Iterator` into a `Stream` which is always ready +/// to yield the next value. +/// +/// Iterators in Rust don't express the ability to block, so this adapter +/// simply always calls `iter.next()` and returns that. +/// +/// ``` +/// # async fn dox() { +/// use tokio_stream::{self as stream, StreamExt}; +/// +/// let mut stream = stream::iter(vec![17, 19]); +/// +/// assert_eq!(stream.next().await, Some(17)); +/// assert_eq!(stream.next().await, Some(19)); +/// assert_eq!(stream.next().await, None); +/// # } +/// ``` +pub fn iter<I>(i: I) -> Iter<I::IntoIter> +where + I: IntoIterator, +{ + Iter { + iter: i.into_iter(), + yield_amt: 0, + } +} + +impl<I> Stream for Iter<I> +where + I: Iterator, +{ + type Item = I::Item; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<I::Item>> { + // TODO: add coop back + if self.yield_amt >= 32 { + self.yield_amt = 0; + + cx.waker().wake_by_ref(); + + Poll::Pending + } else { + self.yield_amt += 1; + + Poll::Ready(self.iter.next()) + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + self.iter.size_hint() + } +} diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 0000000..307a839 --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,105 @@ +#![doc(html_root_url = "https://docs.rs/tokio-stream/0.1.2")] +#![allow( + clippy::cognitive_complexity, + clippy::large_enum_variant, + clippy::needless_doctest_main +)] +#![warn( + missing_debug_implementations, + missing_docs, + rust_2018_idioms, + unreachable_pub +)] +#![cfg_attr(docsrs, deny(broken_intra_doc_links))] +#![doc(test( + no_crate_inject, + attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables)) +))] +#![cfg_attr(docsrs, feature(doc_cfg))] +#![cfg_attr(docsrs, deny(broken_intra_doc_links))] +#![doc(test( + no_crate_inject, + attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables)) +))] +#![cfg_attr(docsrs, feature(doc_cfg))] + +//! Stream utilities for Tokio. +//! +//! A `Stream` is an asynchronous sequence of values. It can be thought of as +//! an asynchronous version of the standard library's `Iterator` trait. +//! +//! This crate provides helpers to work with them. For examples of usage and a more in-depth +//! description of streams you can also refer to the [streams +//! tutorial](https://tokio.rs/tokio/tutorial/streams) on the tokio website. +//! +//! # Iterating over a Stream +//! +//! Due to similarities with the standard library's `Iterator` trait, some new +//! users may assume that they can use `for in` syntax to iterate over a +//! `Stream`, but this is unfortunately not possible. Instead, you can use a +//! `while let` loop as follows: +//! +//! ```rust +//! use tokio_stream::{self as stream, StreamExt}; +//! +//! #[tokio::main] +//! async fn main() { +//! let mut stream = stream::iter(vec![0, 1, 2]); +//! +//! while let Some(value) = stream.next().await { +//! println!("Got {}", value); +//! } +//! } +//! ``` +//! +//! # Returning a Stream from a function +//! +//! A common way to stream values from a function is to pass in the sender +//! half of a channel and use the receiver as the stream. This requires awaiting +//! both futures to ensure progress is made. Another alternative is the +//! [async-stream] crate, which contains macros that provide a `yield` keyword +//! and allow you to return an `impl Stream`. +//! +//! [async-stream]: https://docs.rs/async-stream +//! +//! # Conversion to and from AsyncRead/AsyncWrite +//! +//! It is often desirable to convert a `Stream` into an [`AsyncRead`], +//! especially when dealing with plaintext formats streamed over the network. +//! The opposite conversion from an [`AsyncRead`] into a `Stream` is also +//! another commonly required feature. To enable these conversions, +//! [`tokio-util`] provides the [`StreamReader`] and [`ReaderStream`] +//! types when the io feature is enabled. +//! +//! [`tokio-util`]: https://docs.rs/tokio-util/0.4/tokio_util/codec/index.html +//! [`tokio::io`]: https://docs.rs/tokio/1.0/tokio/io/index.html +//! [`AsyncRead`]: https://docs.rs/tokio/1.0/tokio/io/trait.AsyncRead.html +//! [`AsyncWrite`]: https://docs.rs/tokio/1.0/tokio/io/trait.AsyncWrite.html +//! [`ReaderStream`]: https://docs.rs/tokio-util/0.4/tokio_util/io/struct.ReaderStream.html +//! [`StreamReader`]: https://docs.rs/tokio-util/0.4/tokio_util/io/struct.StreamReader.html + +#[macro_use] +mod macros; + +pub mod wrappers; + +mod stream_ext; +pub use stream_ext::{collect::FromStream, StreamExt}; + +mod empty; +pub use empty::{empty, Empty}; + +mod iter; +pub use iter::{iter, Iter}; + +mod once; +pub use once::{once, Once}; + +mod pending; +pub use pending::{pending, Pending}; + +mod stream_map; +pub use stream_map::StreamMap; + +#[doc(no_inline)] +pub use futures_core::Stream; diff --git a/src/macros.rs b/src/macros.rs new file mode 100644 index 0000000..39ad86c --- /dev/null +++ b/src/macros.rs @@ -0,0 +1,48 @@ +macro_rules! cfg_fs { + ($($item:item)*) => { + $( + #[cfg(feature = "fs")] + #[cfg_attr(docsrs, doc(cfg(feature = "fs")))] + $item + )* + } +} + +macro_rules! cfg_io_util { + ($($item:item)*) => { + $( + #[cfg(feature = "io-util")] + #[cfg_attr(docsrs, doc(cfg(feature = "io-util")))] + $item + )* + } +} + +macro_rules! cfg_net { + ($($item:item)*) => { + $( + #[cfg(feature = "net")] + #[cfg_attr(docsrs, doc(cfg(feature = "net")))] + $item + )* + } +} + +macro_rules! cfg_time { + ($($item:item)*) => { + $( + #[cfg(feature = "time")] + #[cfg_attr(docsrs, doc(cfg(feature = "time")))] + $item + )* + } +} + +macro_rules! ready { + ($e:expr $(,)?) => { + match $e { + std::task::Poll::Ready(t) => t, + std::task::Poll::Pending => return std::task::Poll::Pending, + } + }; +} diff --git a/src/once.rs b/src/once.rs new file mode 100644 index 0000000..04b4c05 --- /dev/null +++ b/src/once.rs @@ -0,0 +1,52 @@ +use crate::{Iter, Stream}; + +use core::option; +use core::pin::Pin; +use core::task::{Context, Poll}; + +/// Stream for the [`once`](fn@once) function. +#[derive(Debug)] +#[must_use = "streams do nothing unless polled"] +pub struct Once<T> { + iter: Iter<option::IntoIter<T>>, +} + +impl<I> Unpin for Once<I> {} + +/// Creates a stream that emits an element exactly once. +/// +/// The returned stream is immediately ready and emits the provided value once. +/// +/// # Examples +/// +/// ``` +/// use tokio_stream::{self as stream, StreamExt}; +/// +/// #[tokio::main] +/// async fn main() { +/// // one is the loneliest number +/// let mut one = stream::once(1); +/// +/// assert_eq!(Some(1), one.next().await); +/// +/// // just one, that's all we get +/// assert_eq!(None, one.next().await); +/// } +/// ``` +pub fn once<T>(value: T) -> Once<T> { + Once { + iter: crate::iter(Some(value).into_iter()), + } +} + +impl<T> Stream for Once<T> { + type Item = T; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>> { + Pin::new(&mut self.iter).poll_next(cx) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + self.iter.size_hint() + } +} diff --git a/src/pending.rs b/src/pending.rs new file mode 100644 index 0000000..b50fd33 --- /dev/null +++ b/src/pending.rs @@ -0,0 +1,54 @@ +use crate::Stream; + +use core::marker::PhantomData; +use core::pin::Pin; +use core::task::{Context, Poll}; + +/// Stream for the [`pending`](fn@pending) function. +#[derive(Debug)] +#[must_use = "streams do nothing unless polled"] +pub struct Pending<T>(PhantomData<T>); + +impl<T> Unpin for Pending<T> {} +unsafe impl<T> Send for Pending<T> {} +unsafe impl<T> Sync for Pending<T> {} + +/// Creates a stream that is never ready +/// +/// The returned stream is never ready. Attempting to call +/// [`next()`](crate::StreamExt::next) will never complete. Use +/// [`stream::empty()`](super::empty()) to obtain a stream that is is +/// immediately empty but returns no values. +/// +/// # Examples +/// +/// Basic usage: +/// +/// ```no_run +/// use tokio_stream::{self as stream, StreamExt}; +/// +/// #[tokio::main] +/// async fn main() { +/// let mut never = stream::pending::<i32>(); +/// +/// // This will never complete +/// never.next().await; +/// +/// unreachable!(); +/// } +/// ``` +pub const fn pending<T>() -> Pending<T> { + Pending(PhantomData) +} + +impl<T> Stream for Pending<T> { + type Item = T; + + fn poll_next(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<T>> { + Poll::Pending + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, None) + } +} diff --git a/src/stream_ext.rs b/src/stream_ext.rs new file mode 100644 index 0000000..51532ee --- /dev/null +++ b/src/stream_ext.rs @@ -0,0 +1,917 @@ +use futures_core::Stream; + +mod all; +use all::AllFuture; + +mod any; +use any::AnyFuture; + +mod chain; +use chain::Chain; + +pub(crate) mod collect; +use collect::{Collect, FromStream}; + +mod filter; +use filter::Filter; + +mod filter_map; +use filter_map::FilterMap; + +mod fold; +use fold::FoldFuture; + +mod fuse; +use fuse::Fuse; + +mod map; +use map::Map; + +mod merge; +use merge::Merge; + +mod next; +use next::Next; + +mod skip; +use skip::Skip; + +mod skip_while; +use skip_while::SkipWhile; + +mod try_next; +use try_next::TryNext; + +mod take; +use take::Take; + +mod take_while; +use take_while::TakeWhile; + +cfg_time! { + mod timeout; + use timeout::Timeout; + use tokio::time::Duration; + mod throttle; + use throttle::{throttle, Throttle}; +} + +/// An extension trait for the [`Stream`] trait that provides a variety of +/// convenient combinator functions. +/// +/// Be aware that the `Stream` trait in Tokio is a re-export of the trait found +/// in the [futures] crate, however both Tokio and futures provide separate +/// `StreamExt` utility traits, and some utilities are only available on one of +/// these traits. Click [here][futures-StreamExt] to see the other `StreamExt` +/// trait in the futures crate. +/// +/// If you need utilities from both `StreamExt` traits, you should prefer to +/// import one of them, and use the other through the fully qualified call +/// syntax. For example: +/// ``` +/// // import one of the traits: +/// use futures::stream::StreamExt; +/// # #[tokio::main(flavor = "current_thread")] +/// # async fn main() { +/// +/// let a = tokio_stream::iter(vec![1, 3, 5]); +/// let b = tokio_stream::iter(vec![2, 4, 6]); +/// +/// // use the fully qualified call syntax for the other trait: +/// let merged = tokio_stream::StreamExt::merge(a, b); +/// +/// // use normal call notation for futures::stream::StreamExt::collect +/// let output: Vec<_> = merged.collect().await; +/// assert_eq!(output, vec![1, 2, 3, 4, 5, 6]); +/// # } +/// ``` +/// +/// [`Stream`]: crate::Stream +/// [futures]: https://docs.rs/futures +/// [futures-StreamExt]: https://docs.rs/futures/0.3/futures/stream/trait.StreamExt.html +pub trait StreamExt: Stream { + /// Consumes and returns the next value in the stream or `None` if the + /// stream is finished. + /// + /// Equivalent to: + /// + /// ```ignore + /// async fn next(&mut self) -> Option<Self::Item>; + /// ``` + /// + /// Note that because `next` doesn't take ownership over the stream, + /// the [`Stream`] type must be [`Unpin`]. If you want to use `next` with a + /// [`!Unpin`](Unpin) stream, you'll first have to pin the stream. This can + /// be done by boxing the stream using [`Box::pin`] or + /// pinning it to the stack using the `pin_mut!` macro from the `pin_utils` + /// crate. + /// + /// # Examples + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let mut stream = stream::iter(1..=3); + /// + /// assert_eq!(stream.next().await, Some(1)); + /// assert_eq!(stream.next().await, Some(2)); + /// assert_eq!(stream.next().await, Some(3)); + /// assert_eq!(stream.next().await, None); + /// # } + /// ``` + fn next(&mut self) -> Next<'_, Self> + where + Self: Unpin, + { + Next::new(self) + } + + /// Consumes and returns the next item in the stream. If an error is + /// encountered before the next item, the error is returned instead. + /// + /// Equivalent to: + /// + /// ```ignore + /// async fn try_next(&mut self) -> Result<Option<T>, E>; + /// ``` + /// + /// This is similar to the [`next`](StreamExt::next) combinator, + /// but returns a [`Result<Option<T>, E>`](Result) rather than + /// an [`Option<Result<T, E>>`](Option), making for easy use + /// with the [`?`](std::ops::Try) operator. + /// + /// # Examples + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let mut stream = stream::iter(vec![Ok(1), Ok(2), Err("nope")]); + /// + /// assert_eq!(stream.try_next().await, Ok(Some(1))); + /// assert_eq!(stream.try_next().await, Ok(Some(2))); + /// assert_eq!(stream.try_next().await, Err("nope")); + /// # } + /// ``` + fn try_next<T, E>(&mut self) -> TryNext<'_, Self> + where + Self: Stream<Item = Result<T, E>> + Unpin, + { + TryNext::new(self) + } + + /// Maps this stream's items to a different type, returning a new stream of + /// the resulting type. + /// + /// The provided closure is executed over all elements of this stream as + /// they are made available. It is executed inline with calls to + /// [`poll_next`](Stream::poll_next). + /// + /// Note that this function consumes the stream passed into it and returns a + /// wrapped version of it, similar to the existing `map` methods in the + /// standard library. + /// + /// # Examples + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let stream = stream::iter(1..=3); + /// let mut stream = stream.map(|x| x + 3); + /// + /// assert_eq!(stream.next().await, Some(4)); + /// assert_eq!(stream.next().await, Some(5)); + /// assert_eq!(stream.next().await, Some(6)); + /// # } + /// ``` + fn map<T, F>(self, f: F) -> Map<Self, F> + where + F: FnMut(Self::Item) -> T, + Self: Sized, + { + Map::new(self, f) + } + + /// Combine two streams into one by interleaving the output of both as it + /// is produced. + /// + /// Values are produced from the merged stream in the order they arrive from + /// the two source streams. If both source streams provide values + /// simultaneously, the merge stream alternates between them. This provides + /// some level of fairness. You should not chain calls to `merge`, as this + /// will break the fairness of the merging. + /// + /// The merged stream completes once **both** source streams complete. When + /// one source stream completes before the other, the merge stream + /// exclusively polls the remaining stream. + /// + /// For merging multiple streams, consider using [`StreamMap`] instead. + /// + /// [`StreamMap`]: crate::StreamMap + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamExt, Stream}; + /// use tokio::sync::mpsc; + /// use tokio::time; + /// + /// use std::time::Duration; + /// use std::pin::Pin; + /// + /// # /* + /// #[tokio::main] + /// # */ + /// # #[tokio::main(flavor = "current_thread")] + /// async fn main() { + /// # time::pause(); + /// let (tx1, mut rx1) = mpsc::channel::<usize>(10); + /// let (tx2, mut rx2) = mpsc::channel::<usize>(10); + /// + /// // Convert the channels to a `Stream`. + /// let rx1 = Box::pin(async_stream::stream! { + /// while let Some(item) = rx1.recv().await { + /// yield item; + /// } + /// }) as Pin<Box<dyn Stream<Item = usize> + Send>>; + /// + /// let rx2 = Box::pin(async_stream::stream! { + /// while let Some(item) = rx2.recv().await { + /// yield item; + /// } + /// }) as Pin<Box<dyn Stream<Item = usize> + Send>>; + /// + /// let mut rx = rx1.merge(rx2); + /// + /// tokio::spawn(async move { + /// // Send some values immediately + /// tx1.send(1).await.unwrap(); + /// tx1.send(2).await.unwrap(); + /// + /// // Let the other task send values + /// time::sleep(Duration::from_millis(20)).await; + /// + /// tx1.send(4).await.unwrap(); + /// }); + /// + /// tokio::spawn(async move { + /// // Wait for the first task to send values + /// time::sleep(Duration::from_millis(5)).await; + /// + /// tx2.send(3).await.unwrap(); + /// + /// time::sleep(Duration::from_millis(25)).await; + /// + /// // Send the final value + /// tx2.send(5).await.unwrap(); + /// }); + /// + /// assert_eq!(1, rx.next().await.unwrap()); + /// assert_eq!(2, rx.next().await.unwrap()); + /// assert_eq!(3, rx.next().await.unwrap()); + /// assert_eq!(4, rx.next().await.unwrap()); + /// assert_eq!(5, rx.next().await.unwrap()); + /// + /// // The merged stream is consumed + /// assert!(rx.next().await.is_none()); + /// } + /// ``` + fn merge<U>(self, other: U) -> Merge<Self, U> + where + U: Stream<Item = Self::Item>, + Self: Sized, + { + Merge::new(self, other) + } + + /// Filters the values produced by this stream according to the provided + /// predicate. + /// + /// As values of this stream are made available, the provided predicate `f` + /// will be run against them. If the predicate + /// resolves to `true`, then the stream will yield the value, but if the + /// predicate resolves to `false`, then the value + /// will be discarded and the next value will be produced. + /// + /// Note that this function consumes the stream passed into it and returns a + /// wrapped version of it, similar to [`Iterator::filter`] method in the + /// standard library. + /// + /// # Examples + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let stream = stream::iter(1..=8); + /// let mut evens = stream.filter(|x| x % 2 == 0); + /// + /// assert_eq!(Some(2), evens.next().await); + /// assert_eq!(Some(4), evens.next().await); + /// assert_eq!(Some(6), evens.next().await); + /// assert_eq!(Some(8), evens.next().await); + /// assert_eq!(None, evens.next().await); + /// # } + /// ``` + fn filter<F>(self, f: F) -> Filter<Self, F> + where + F: FnMut(&Self::Item) -> bool, + Self: Sized, + { + Filter::new(self, f) + } + + /// Filters the values produced by this stream while simultaneously mapping + /// them to a different type according to the provided closure. + /// + /// As values of this stream are made available, the provided function will + /// be run on them. If the predicate `f` resolves to + /// [`Some(item)`](Some) then the stream will yield the value `item`, but if + /// it resolves to [`None`], then the value will be skipped. + /// + /// Note that this function consumes the stream passed into it and returns a + /// wrapped version of it, similar to [`Iterator::filter_map`] method in the + /// standard library. + /// + /// # Examples + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let stream = stream::iter(1..=8); + /// let mut evens = stream.filter_map(|x| { + /// if x % 2 == 0 { Some(x + 1) } else { None } + /// }); + /// + /// assert_eq!(Some(3), evens.next().await); + /// assert_eq!(Some(5), evens.next().await); + /// assert_eq!(Some(7), evens.next().await); + /// assert_eq!(Some(9), evens.next().await); + /// assert_eq!(None, evens.next().await); + /// # } + /// ``` + fn filter_map<T, F>(self, f: F) -> FilterMap<Self, F> + where + F: FnMut(Self::Item) -> Option<T>, + Self: Sized, + { + FilterMap::new(self, f) + } + + /// Creates a stream which ends after the first `None`. + /// + /// After a stream returns `None`, behavior is undefined. Future calls to + /// `poll_next` may or may not return `Some(T)` again or they may panic. + /// `fuse()` adapts a stream, ensuring that after `None` is given, it will + /// return `None` forever. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{Stream, StreamExt}; + /// + /// use std::pin::Pin; + /// use std::task::{Context, Poll}; + /// + /// // a stream which alternates between Some and None + /// struct Alternate { + /// state: i32, + /// } + /// + /// impl Stream for Alternate { + /// type Item = i32; + /// + /// fn poll_next(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<i32>> { + /// let val = self.state; + /// self.state = self.state + 1; + /// + /// // if it's even, Some(i32), else None + /// if val % 2 == 0 { + /// Poll::Ready(Some(val)) + /// } else { + /// Poll::Ready(None) + /// } + /// } + /// } + /// + /// #[tokio::main] + /// async fn main() { + /// let mut stream = Alternate { state: 0 }; + /// + /// // the stream goes back and forth + /// assert_eq!(stream.next().await, Some(0)); + /// assert_eq!(stream.next().await, None); + /// assert_eq!(stream.next().await, Some(2)); + /// assert_eq!(stream.next().await, None); + /// + /// // however, once it is fused + /// let mut stream = stream.fuse(); + /// + /// assert_eq!(stream.next().await, Some(4)); + /// assert_eq!(stream.next().await, None); + /// + /// // it will always return `None` after the first time. + /// assert_eq!(stream.next().await, None); + /// assert_eq!(stream.next().await, None); + /// assert_eq!(stream.next().await, None); + /// } + /// ``` + fn fuse(self) -> Fuse<Self> + where + Self: Sized, + { + Fuse::new(self) + } + + /// Creates a new stream of at most `n` items of the underlying stream. + /// + /// Once `n` items have been yielded from this stream then it will always + /// return that the stream is done. + /// + /// # Examples + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let mut stream = stream::iter(1..=10).take(3); + /// + /// assert_eq!(Some(1), stream.next().await); + /// assert_eq!(Some(2), stream.next().await); + /// assert_eq!(Some(3), stream.next().await); + /// assert_eq!(None, stream.next().await); + /// # } + /// ``` + fn take(self, n: usize) -> Take<Self> + where + Self: Sized, + { + Take::new(self, n) + } + + /// Take elements from this stream while the provided predicate + /// resolves to `true`. + /// + /// This function, like `Iterator::take_while`, will take elements from the + /// stream until the predicate `f` resolves to `false`. Once one element + /// returns false it will always return that the stream is done. + /// + /// # Examples + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let mut stream = stream::iter(1..=10).take_while(|x| *x <= 3); + /// + /// assert_eq!(Some(1), stream.next().await); + /// assert_eq!(Some(2), stream.next().await); + /// assert_eq!(Some(3), stream.next().await); + /// assert_eq!(None, stream.next().await); + /// # } + /// ``` + fn take_while<F>(self, f: F) -> TakeWhile<Self, F> + where + F: FnMut(&Self::Item) -> bool, + Self: Sized, + { + TakeWhile::new(self, f) + } + + /// Creates a new stream that will skip the `n` first items of the + /// underlying stream. + /// + /// # Examples + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let mut stream = stream::iter(1..=10).skip(7); + /// + /// assert_eq!(Some(8), stream.next().await); + /// assert_eq!(Some(9), stream.next().await); + /// assert_eq!(Some(10), stream.next().await); + /// assert_eq!(None, stream.next().await); + /// # } + /// ``` + fn skip(self, n: usize) -> Skip<Self> + where + Self: Sized, + { + Skip::new(self, n) + } + + /// Skip elements from the underlying stream while the provided predicate + /// resolves to `true`. + /// + /// This function, like [`Iterator::skip_while`], will ignore elemets from the + /// stream until the predicate `f` resolves to `false`. Once one element + /// returns false, the rest of the elements will be yielded. + /// + /// [`Iterator::skip_while`]: std::iter::Iterator::skip_while() + /// + /// # Examples + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// let mut stream = stream::iter(vec![1,2,3,4,1]).skip_while(|x| *x < 3); + /// + /// assert_eq!(Some(3), stream.next().await); + /// assert_eq!(Some(4), stream.next().await); + /// assert_eq!(Some(1), stream.next().await); + /// assert_eq!(None, stream.next().await); + /// # } + /// ``` + fn skip_while<F>(self, f: F) -> SkipWhile<Self, F> + where + F: FnMut(&Self::Item) -> bool, + Self: Sized, + { + SkipWhile::new(self, f) + } + + /// Tests if every element of the stream matches a predicate. + /// + /// Equivalent to: + /// + /// ```ignore + /// async fn all<F>(&mut self, f: F) -> bool; + /// ``` + /// + /// `all()` takes a closure that returns `true` or `false`. It applies + /// this closure to each element of the stream, and if they all return + /// `true`, then so does `all`. If any of them return `false`, it + /// returns `false`. An empty stream returns `true`. + /// + /// `all()` is short-circuiting; in other words, it will stop processing + /// as soon as it finds a `false`, given that no matter what else happens, + /// the result will also be `false`. + /// + /// An empty stream returns `true`. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let a = [1, 2, 3]; + /// + /// assert!(stream::iter(&a).all(|&x| x > 0).await); + /// + /// assert!(!stream::iter(&a).all(|&x| x > 2).await); + /// # } + /// ``` + /// + /// Stopping at the first `false`: + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let a = [1, 2, 3]; + /// + /// let mut iter = stream::iter(&a); + /// + /// assert!(!iter.all(|&x| x != 2).await); + /// + /// // we can still use `iter`, as there are more elements. + /// assert_eq!(iter.next().await, Some(&3)); + /// # } + /// ``` + fn all<F>(&mut self, f: F) -> AllFuture<'_, Self, F> + where + Self: Unpin, + F: FnMut(Self::Item) -> bool, + { + AllFuture::new(self, f) + } + + /// Tests if any element of the stream matches a predicate. + /// + /// Equivalent to: + /// + /// ```ignore + /// async fn any<F>(&mut self, f: F) -> bool; + /// ``` + /// + /// `any()` takes a closure that returns `true` or `false`. It applies + /// this closure to each element of the stream, and if any of them return + /// `true`, then so does `any()`. If they all return `false`, it + /// returns `false`. + /// + /// `any()` is short-circuiting; in other words, it will stop processing + /// as soon as it finds a `true`, given that no matter what else happens, + /// the result will also be `true`. + /// + /// An empty stream returns `false`. + /// + /// Basic usage: + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let a = [1, 2, 3]; + /// + /// assert!(stream::iter(&a).any(|&x| x > 0).await); + /// + /// assert!(!stream::iter(&a).any(|&x| x > 5).await); + /// # } + /// ``` + /// + /// Stopping at the first `true`: + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// let a = [1, 2, 3]; + /// + /// let mut iter = stream::iter(&a); + /// + /// assert!(iter.any(|&x| x != 2).await); + /// + /// // we can still use `iter`, as there are more elements. + /// assert_eq!(iter.next().await, Some(&2)); + /// # } + /// ``` + fn any<F>(&mut self, f: F) -> AnyFuture<'_, Self, F> + where + Self: Unpin, + F: FnMut(Self::Item) -> bool, + { + AnyFuture::new(self, f) + } + + /// Combine two streams into one by first returning all values from the + /// first stream then all values from the second stream. + /// + /// As long as `self` still has values to emit, no values from `other` are + /// emitted, even if some are ready. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// #[tokio::main] + /// async fn main() { + /// let one = stream::iter(vec![1, 2, 3]); + /// let two = stream::iter(vec![4, 5, 6]); + /// + /// let mut stream = one.chain(two); + /// + /// assert_eq!(stream.next().await, Some(1)); + /// assert_eq!(stream.next().await, Some(2)); + /// assert_eq!(stream.next().await, Some(3)); + /// assert_eq!(stream.next().await, Some(4)); + /// assert_eq!(stream.next().await, Some(5)); + /// assert_eq!(stream.next().await, Some(6)); + /// assert_eq!(stream.next().await, None); + /// } + /// ``` + fn chain<U>(self, other: U) -> Chain<Self, U> + where + U: Stream<Item = Self::Item>, + Self: Sized, + { + Chain::new(self, other) + } + + /// A combinator that applies a function to every element in a stream + /// producing a single, final value. + /// + /// Equivalent to: + /// + /// ```ignore + /// async fn fold<B, F>(self, init: B, f: F) -> B; + /// ``` + /// + /// # Examples + /// Basic usage: + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, *}; + /// + /// let s = stream::iter(vec![1u8, 2, 3]); + /// let sum = s.fold(0, |acc, x| acc + x).await; + /// + /// assert_eq!(sum, 6); + /// # } + /// ``` + fn fold<B, F>(self, init: B, f: F) -> FoldFuture<Self, B, F> + where + Self: Sized, + F: FnMut(B, Self::Item) -> B, + { + FoldFuture::new(self, init, f) + } + + /// Drain stream pushing all emitted values into a collection. + /// + /// Equivalent to: + /// + /// ```ignore + /// async fn collect<T>(self) -> T; + /// ``` + /// + /// `collect` streams all values, awaiting as needed. Values are pushed into + /// a collection. A number of different target collection types are + /// supported, including [`Vec`](std::vec::Vec), + /// [`String`](std::string::String), and [`Bytes`]. + /// + /// [`Bytes`]: https://docs.rs/bytes/0.6.0/bytes/struct.Bytes.html + /// + /// # `Result` + /// + /// `collect()` can also be used with streams of type `Result<T, E>` where + /// `T: FromStream<_>`. In this case, `collect()` will stream as long as + /// values yielded from the stream are `Ok(_)`. If `Err(_)` is encountered, + /// streaming is terminated and `collect()` returns the `Err`. + /// + /// # Notes + /// + /// `FromStream` is currently a sealed trait. Stabilization is pending + /// enhancements to the Rust language. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// #[tokio::main] + /// async fn main() { + /// let doubled: Vec<i32> = + /// stream::iter(vec![1, 2, 3]) + /// .map(|x| x * 2) + /// .collect() + /// .await; + /// + /// assert_eq!(vec![2, 4, 6], doubled); + /// } + /// ``` + /// + /// Collecting a stream of `Result` values + /// + /// ``` + /// use tokio_stream::{self as stream, StreamExt}; + /// + /// #[tokio::main] + /// async fn main() { + /// // A stream containing only `Ok` values will be collected + /// let values: Result<Vec<i32>, &str> = + /// stream::iter(vec![Ok(1), Ok(2), Ok(3)]) + /// .collect() + /// .await; + /// + /// assert_eq!(Ok(vec![1, 2, 3]), values); + /// + /// // A stream containing `Err` values will return the first error. + /// let results = vec![Ok(1), Err("no"), Ok(2), Ok(3), Err("nein")]; + /// + /// let values: Result<Vec<i32>, &str> = + /// stream::iter(results) + /// .collect() + /// .await; + /// + /// assert_eq!(Err("no"), values); + /// } + /// ``` + fn collect<T>(self) -> Collect<Self, T> + where + T: FromStream<Self::Item>, + Self: Sized, + { + Collect::new(self) + } + + /// Applies a per-item timeout to the passed stream. + /// + /// `timeout()` takes a `Duration` that represents the maximum amount of + /// time each element of the stream has to complete before timing out. + /// + /// If the wrapped stream yields a value before the deadline is reached, the + /// value is returned. Otherwise, an error is returned. The caller may decide + /// to continue consuming the stream and will eventually get the next source + /// stream value once it becomes available. + /// + /// # Notes + /// + /// This function consumes the stream passed into it and returns a + /// wrapped version of it. + /// + /// Polling the returned stream will continue to poll the inner stream even + /// if one or more items time out. + /// + /// # Examples + /// + /// Suppose we have a stream `int_stream` that yields 3 numbers (1, 2, 3): + /// + /// ``` + /// # #[tokio::main] + /// # async fn main() { + /// use tokio_stream::{self as stream, StreamExt}; + /// use std::time::Duration; + /// # let int_stream = stream::iter(1..=3); + /// + /// let int_stream = int_stream.timeout(Duration::from_secs(1)); + /// tokio::pin!(int_stream); + /// + /// // When no items time out, we get the 3 elements in succession: + /// assert_eq!(int_stream.try_next().await, Ok(Some(1))); + /// assert_eq!(int_stream.try_next().await, Ok(Some(2))); + /// assert_eq!(int_stream.try_next().await, Ok(Some(3))); + /// assert_eq!(int_stream.try_next().await, Ok(None)); + /// + /// // If the second item times out, we get an error and continue polling the stream: + /// # let mut int_stream = stream::iter(vec![Ok(1), Err(()), Ok(2), Ok(3)]); + /// assert_eq!(int_stream.try_next().await, Ok(Some(1))); + /// assert!(int_stream.try_next().await.is_err()); + /// assert_eq!(int_stream.try_next().await, Ok(Some(2))); + /// assert_eq!(int_stream.try_next().await, Ok(Some(3))); + /// assert_eq!(int_stream.try_next().await, Ok(None)); + /// + /// // If we want to stop consuming the source stream the first time an + /// // element times out, we can use the `take_while` operator: + /// # let int_stream = stream::iter(vec![Ok(1), Err(()), Ok(2), Ok(3)]); + /// let mut int_stream = int_stream.take_while(Result::is_ok); + /// + /// assert_eq!(int_stream.try_next().await, Ok(Some(1))); + /// assert_eq!(int_stream.try_next().await, Ok(None)); + /// # } + /// ``` + #[cfg(all(feature = "time"))] + #[cfg_attr(docsrs, doc(cfg(feature = "time")))] + fn timeout(self, duration: Duration) -> Timeout<Self> + where + Self: Sized, + { + Timeout::new(self, duration) + } + + /// Slows down a stream by enforcing a delay between items. + /// + /// # Example + /// + /// Create a throttled stream. + /// ```rust,no_run + /// use std::time::Duration; + /// use tokio_stream::StreamExt; + /// + /// # async fn dox() { + /// let item_stream = futures::stream::repeat("one").throttle(Duration::from_secs(2)); + /// tokio::pin!(item_stream); + /// + /// loop { + /// // The string will be produced at most every 2 seconds + /// println!("{:?}", item_stream.next().await); + /// } + /// # } + /// ``` + #[cfg(all(feature = "time"))] + #[cfg_attr(docsrs, doc(cfg(feature = "time")))] + fn throttle(self, duration: Duration) -> Throttle<Self> + where + Self: Sized, + { + throttle(duration, self) + } +} + +impl<St: ?Sized> StreamExt for St where St: Stream {} + +/// Merge the size hints from two streams. +fn merge_size_hints( + (left_low, left_high): (usize, Option<usize>), + (right_low, right_hign): (usize, Option<usize>), +) -> (usize, Option<usize>) { + let low = left_low.saturating_add(right_low); + let high = match (left_high, right_hign) { + (Some(h1), Some(h2)) => h1.checked_add(h2), + _ => None, + }; + (low, high) +} diff --git a/src/stream_ext/all.rs b/src/stream_ext/all.rs new file mode 100644 index 0000000..11573f9 --- /dev/null +++ b/src/stream_ext/all.rs @@ -0,0 +1,55 @@ +use crate::Stream; + +use core::future::Future; +use core::marker::PhantomPinned; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Future for the [`all`](super::StreamExt::all) method. + #[derive(Debug)] + #[must_use = "futures do nothing unless you `.await` or poll them"] + pub struct AllFuture<'a, St: ?Sized, F> { + stream: &'a mut St, + f: F, + // Make this future `!Unpin` for compatibility with async trait methods. + #[pin] + _pin: PhantomPinned, + } +} + +impl<'a, St: ?Sized, F> AllFuture<'a, St, F> { + pub(super) fn new(stream: &'a mut St, f: F) -> Self { + Self { + stream, + f, + _pin: PhantomPinned, + } + } +} + +impl<St, F> Future for AllFuture<'_, St, F> +where + St: ?Sized + Stream + Unpin, + F: FnMut(St::Item) -> bool, +{ + type Output = bool; + + fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { + let me = self.project(); + let next = futures_core::ready!(Pin::new(me.stream).poll_next(cx)); + + match next { + Some(v) => { + if !(me.f)(v) { + Poll::Ready(false) + } else { + cx.waker().wake_by_ref(); + Poll::Pending + } + } + None => Poll::Ready(true), + } + } +} diff --git a/src/stream_ext/any.rs b/src/stream_ext/any.rs new file mode 100644 index 0000000..4c4c593 --- /dev/null +++ b/src/stream_ext/any.rs @@ -0,0 +1,55 @@ +use crate::Stream; + +use core::future::Future; +use core::marker::PhantomPinned; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Future for the [`any`](super::StreamExt::any) method. + #[derive(Debug)] + #[must_use = "futures do nothing unless you `.await` or poll them"] + pub struct AnyFuture<'a, St: ?Sized, F> { + stream: &'a mut St, + f: F, + // Make this future `!Unpin` for compatibility with async trait methods. + #[pin] + _pin: PhantomPinned, + } +} + +impl<'a, St: ?Sized, F> AnyFuture<'a, St, F> { + pub(super) fn new(stream: &'a mut St, f: F) -> Self { + Self { + stream, + f, + _pin: PhantomPinned, + } + } +} + +impl<St, F> Future for AnyFuture<'_, St, F> +where + St: ?Sized + Stream + Unpin, + F: FnMut(St::Item) -> bool, +{ + type Output = bool; + + fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { + let me = self.project(); + let next = futures_core::ready!(Pin::new(me.stream).poll_next(cx)); + + match next { + Some(v) => { + if (me.f)(v) { + Poll::Ready(true) + } else { + cx.waker().wake_by_ref(); + Poll::Pending + } + } + None => Poll::Ready(false), + } + } +} diff --git a/src/stream_ext/chain.rs b/src/stream_ext/chain.rs new file mode 100644 index 0000000..bd64f33 --- /dev/null +++ b/src/stream_ext/chain.rs @@ -0,0 +1,50 @@ +use crate::stream_ext::Fuse; +use crate::Stream; + +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Stream returned by the [`chain`](super::StreamExt::chain) method. + pub struct Chain<T, U> { + #[pin] + a: Fuse<T>, + #[pin] + b: U, + } +} + +impl<T, U> Chain<T, U> { + pub(super) fn new(a: T, b: U) -> Chain<T, U> + where + T: Stream, + U: Stream, + { + Chain { a: Fuse::new(a), b } + } +} + +impl<T, U> Stream for Chain<T, U> +where + T: Stream, + U: Stream<Item = T::Item>, +{ + type Item = T::Item; + + fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T::Item>> { + use Poll::Ready; + + let me = self.project(); + + if let Some(v) = ready!(me.a.poll_next(cx)) { + return Ready(Some(v)); + } + + me.b.poll_next(cx) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + super::merge_size_hints(self.a.size_hint(), self.b.size_hint()) + } +} diff --git a/src/stream_ext/collect.rs b/src/stream_ext/collect.rs new file mode 100644 index 0000000..23f48b0 --- /dev/null +++ b/src/stream_ext/collect.rs @@ -0,0 +1,233 @@ +use crate::Stream; + +use core::future::Future; +use core::marker::PhantomPinned; +use core::mem; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +// Do not export this struct until `FromStream` can be unsealed. +pin_project! { + /// Future returned by the [`collect`](super::StreamExt::collect) method. + #[must_use = "futures do nothing unless you `.await` or poll them"] + #[derive(Debug)] + pub struct Collect<T, U> + where + T: Stream, + U: FromStream<T::Item>, + { + #[pin] + stream: T, + collection: U::InternalCollection, + // Make this future `!Unpin` for compatibility with async trait methods. + #[pin] + _pin: PhantomPinned, + } +} + +/// Convert from a [`Stream`](crate::Stream). +/// +/// This trait is not intended to be used directly. Instead, call +/// [`StreamExt::collect()`](super::StreamExt::collect). +/// +/// # Implementing +/// +/// Currently, this trait may not be implemented by third parties. The trait is +/// sealed in order to make changes in the future. Stabilization is pending +/// enhancements to the Rust language. +pub trait FromStream<T>: sealed::FromStreamPriv<T> {} + +impl<T, U> Collect<T, U> +where + T: Stream, + U: FromStream<T::Item>, +{ + pub(super) fn new(stream: T) -> Collect<T, U> { + let (lower, upper) = stream.size_hint(); + let collection = U::initialize(sealed::Internal, lower, upper); + + Collect { + stream, + collection, + _pin: PhantomPinned, + } + } +} + +impl<T, U> Future for Collect<T, U> +where + T: Stream, + U: FromStream<T::Item>, +{ + type Output = U; + + fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<U> { + use Poll::Ready; + + loop { + let mut me = self.as_mut().project(); + + let item = match ready!(me.stream.poll_next(cx)) { + Some(item) => item, + None => { + return Ready(U::finalize(sealed::Internal, &mut me.collection)); + } + }; + + if !U::extend(sealed::Internal, &mut me.collection, item) { + return Ready(U::finalize(sealed::Internal, &mut me.collection)); + } + } + } +} + +// ===== FromStream implementations + +impl FromStream<()> for () {} + +impl sealed::FromStreamPriv<()> for () { + type InternalCollection = (); + + fn initialize(_: sealed::Internal, _lower: usize, _upper: Option<usize>) {} + + fn extend(_: sealed::Internal, _collection: &mut (), _item: ()) -> bool { + true + } + + fn finalize(_: sealed::Internal, _collection: &mut ()) {} +} + +impl<T: AsRef<str>> FromStream<T> for String {} + +impl<T: AsRef<str>> sealed::FromStreamPriv<T> for String { + type InternalCollection = String; + + fn initialize(_: sealed::Internal, _lower: usize, _upper: Option<usize>) -> String { + String::new() + } + + fn extend(_: sealed::Internal, collection: &mut String, item: T) -> bool { + collection.push_str(item.as_ref()); + true + } + + fn finalize(_: sealed::Internal, collection: &mut String) -> String { + mem::replace(collection, String::new()) + } +} + +impl<T> FromStream<T> for Vec<T> {} + +impl<T> sealed::FromStreamPriv<T> for Vec<T> { + type InternalCollection = Vec<T>; + + fn initialize(_: sealed::Internal, lower: usize, _upper: Option<usize>) -> Vec<T> { + Vec::with_capacity(lower) + } + + fn extend(_: sealed::Internal, collection: &mut Vec<T>, item: T) -> bool { + collection.push(item); + true + } + + fn finalize(_: sealed::Internal, collection: &mut Vec<T>) -> Vec<T> { + mem::replace(collection, vec![]) + } +} + +impl<T> FromStream<T> for Box<[T]> {} + +impl<T> sealed::FromStreamPriv<T> for Box<[T]> { + type InternalCollection = Vec<T>; + + fn initialize(_: sealed::Internal, lower: usize, upper: Option<usize>) -> Vec<T> { + <Vec<T> as sealed::FromStreamPriv<T>>::initialize(sealed::Internal, lower, upper) + } + + fn extend(_: sealed::Internal, collection: &mut Vec<T>, item: T) -> bool { + <Vec<T> as sealed::FromStreamPriv<T>>::extend(sealed::Internal, collection, item) + } + + fn finalize(_: sealed::Internal, collection: &mut Vec<T>) -> Box<[T]> { + <Vec<T> as sealed::FromStreamPriv<T>>::finalize(sealed::Internal, collection) + .into_boxed_slice() + } +} + +impl<T, U, E> FromStream<Result<T, E>> for Result<U, E> where U: FromStream<T> {} + +impl<T, U, E> sealed::FromStreamPriv<Result<T, E>> for Result<U, E> +where + U: FromStream<T>, +{ + type InternalCollection = Result<U::InternalCollection, E>; + + fn initialize( + _: sealed::Internal, + lower: usize, + upper: Option<usize>, + ) -> Result<U::InternalCollection, E> { + Ok(U::initialize(sealed::Internal, lower, upper)) + } + + fn extend( + _: sealed::Internal, + collection: &mut Self::InternalCollection, + item: Result<T, E>, + ) -> bool { + assert!(collection.is_ok()); + match item { + Ok(item) => { + let collection = collection.as_mut().ok().expect("invalid state"); + U::extend(sealed::Internal, collection, item) + } + Err(err) => { + *collection = Err(err); + false + } + } + } + + fn finalize(_: sealed::Internal, collection: &mut Self::InternalCollection) -> Result<U, E> { + if let Ok(collection) = collection.as_mut() { + Ok(U::finalize(sealed::Internal, collection)) + } else { + let res = mem::replace(collection, Ok(U::initialize(sealed::Internal, 0, Some(0)))); + + if let Err(err) = res { + Err(err) + } else { + unreachable!(); + } + } + } +} + +pub(crate) mod sealed { + #[doc(hidden)] + pub trait FromStreamPriv<T> { + /// Intermediate type used during collection process + /// + /// The name of this type is internal and cannot be relied upon. + type InternalCollection; + + /// Initialize the collection + fn initialize( + internal: Internal, + lower: usize, + upper: Option<usize>, + ) -> Self::InternalCollection; + + /// Extend the collection with the received item + /// + /// Return `true` to continue streaming, `false` complete collection. + fn extend(internal: Internal, collection: &mut Self::InternalCollection, item: T) -> bool; + + /// Finalize collection into target type. + fn finalize(internal: Internal, collection: &mut Self::InternalCollection) -> Self; + } + + #[allow(missing_debug_implementations)] + pub struct Internal; +} diff --git a/src/stream_ext/filter.rs b/src/stream_ext/filter.rs new file mode 100644 index 0000000..f3dd871 --- /dev/null +++ b/src/stream_ext/filter.rs @@ -0,0 +1,58 @@ +use crate::Stream; + +use core::fmt; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Stream returned by the [`filter`](super::StreamExt::filter) method. + #[must_use = "streams do nothing unless polled"] + pub struct Filter<St, F> { + #[pin] + stream: St, + f: F, + } +} + +impl<St, F> fmt::Debug for Filter<St, F> +where + St: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("Filter") + .field("stream", &self.stream) + .finish() + } +} + +impl<St, F> Filter<St, F> { + pub(super) fn new(stream: St, f: F) -> Self { + Self { stream, f } + } +} + +impl<St, F> Stream for Filter<St, F> +where + St: Stream, + F: FnMut(&St::Item) -> bool, +{ + type Item = St::Item; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<St::Item>> { + loop { + match ready!(self.as_mut().project().stream.poll_next(cx)) { + Some(e) => { + if (self.as_mut().project().f)(&e) { + return Poll::Ready(Some(e)); + } + } + None => return Poll::Ready(None), + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, self.stream.size_hint().1) // can't know a lower bound, due to the predicate + } +} diff --git a/src/stream_ext/filter_map.rs b/src/stream_ext/filter_map.rs new file mode 100644 index 0000000..fe604a6 --- /dev/null +++ b/src/stream_ext/filter_map.rs @@ -0,0 +1,58 @@ +use crate::Stream; + +use core::fmt; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Stream returned by the [`filter_map`](super::StreamExt::filter_map) method. + #[must_use = "streams do nothing unless polled"] + pub struct FilterMap<St, F> { + #[pin] + stream: St, + f: F, + } +} + +impl<St, F> fmt::Debug for FilterMap<St, F> +where + St: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("FilterMap") + .field("stream", &self.stream) + .finish() + } +} + +impl<St, F> FilterMap<St, F> { + pub(super) fn new(stream: St, f: F) -> Self { + Self { stream, f } + } +} + +impl<St, F, T> Stream for FilterMap<St, F> +where + St: Stream, + F: FnMut(St::Item) -> Option<T>, +{ + type Item = T; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>> { + loop { + match ready!(self.as_mut().project().stream.poll_next(cx)) { + Some(e) => { + if let Some(e) = (self.as_mut().project().f)(e) { + return Poll::Ready(Some(e)); + } + } + None => return Poll::Ready(None), + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, self.stream.size_hint().1) // can't know a lower bound, due to the predicate + } +} diff --git a/src/stream_ext/fold.rs b/src/stream_ext/fold.rs new file mode 100644 index 0000000..e2e97d8 --- /dev/null +++ b/src/stream_ext/fold.rs @@ -0,0 +1,57 @@ +use crate::Stream; + +use core::future::Future; +use core::marker::PhantomPinned; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Future returned by the [`fold`](super::StreamExt::fold) method. + #[derive(Debug)] + #[must_use = "futures do nothing unless you `.await` or poll them"] + pub struct FoldFuture<St, B, F> { + #[pin] + stream: St, + acc: Option<B>, + f: F, + // Make this future `!Unpin` for compatibility with async trait methods. + #[pin] + _pin: PhantomPinned, + } +} + +impl<St, B, F> FoldFuture<St, B, F> { + pub(super) fn new(stream: St, init: B, f: F) -> Self { + Self { + stream, + acc: Some(init), + f, + _pin: PhantomPinned, + } + } +} + +impl<St, B, F> Future for FoldFuture<St, B, F> +where + St: Stream, + F: FnMut(B, St::Item) -> B, +{ + type Output = B; + + fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { + let mut me = self.project(); + loop { + let next = ready!(me.stream.as_mut().poll_next(cx)); + + match next { + Some(v) => { + let old = me.acc.take().unwrap(); + let new = (me.f)(old, v); + *me.acc = Some(new); + } + None => return Poll::Ready(me.acc.take().unwrap()), + } + } + } +} diff --git a/src/stream_ext/fuse.rs b/src/stream_ext/fuse.rs new file mode 100644 index 0000000..2500641 --- /dev/null +++ b/src/stream_ext/fuse.rs @@ -0,0 +1,53 @@ +use crate::Stream; + +use pin_project_lite::pin_project; +use std::pin::Pin; +use std::task::{Context, Poll}; + +pin_project! { + /// Stream returned by [`fuse()`][super::StreamExt::fuse]. + #[derive(Debug)] + pub struct Fuse<T> { + #[pin] + stream: Option<T>, + } +} + +impl<T> Fuse<T> +where + T: Stream, +{ + pub(crate) fn new(stream: T) -> Fuse<T> { + Fuse { + stream: Some(stream), + } + } +} + +impl<T> Stream for Fuse<T> +where + T: Stream, +{ + type Item = T::Item; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T::Item>> { + let res = match Option::as_pin_mut(self.as_mut().project().stream) { + Some(stream) => ready!(stream.poll_next(cx)), + None => return Poll::Ready(None), + }; + + if res.is_none() { + // Do not poll the stream anymore + self.as_mut().project().stream.set(None); + } + + Poll::Ready(res) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + match self.stream { + Some(ref stream) => stream.size_hint(), + None => (0, Some(0)), + } + } +} diff --git a/src/stream_ext/map.rs b/src/stream_ext/map.rs new file mode 100644 index 0000000..e6b47cd --- /dev/null +++ b/src/stream_ext/map.rs @@ -0,0 +1,51 @@ +use crate::Stream; + +use core::fmt; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Stream for the [`map`](super::StreamExt::map) method. + #[must_use = "streams do nothing unless polled"] + pub struct Map<St, F> { + #[pin] + stream: St, + f: F, + } +} + +impl<St, F> fmt::Debug for Map<St, F> +where + St: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("Map").field("stream", &self.stream).finish() + } +} + +impl<St, F> Map<St, F> { + pub(super) fn new(stream: St, f: F) -> Self { + Map { stream, f } + } +} + +impl<St, F, T> Stream for Map<St, F> +where + St: Stream, + F: FnMut(St::Item) -> T, +{ + type Item = T; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>> { + self.as_mut() + .project() + .stream + .poll_next(cx) + .map(|opt| opt.map(|x| (self.as_mut().project().f)(x))) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + self.stream.size_hint() + } +} diff --git a/src/stream_ext/merge.rs b/src/stream_ext/merge.rs new file mode 100644 index 0000000..9d5123c --- /dev/null +++ b/src/stream_ext/merge.rs @@ -0,0 +1,90 @@ +use crate::stream_ext::Fuse; +use crate::Stream; + +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Stream returned by the [`merge`](super::StreamExt::merge) method. + pub struct Merge<T, U> { + #[pin] + a: Fuse<T>, + #[pin] + b: Fuse<U>, + // When `true`, poll `a` first, otherwise, `poll` b`. + a_first: bool, + } +} + +impl<T, U> Merge<T, U> { + pub(super) fn new(a: T, b: U) -> Merge<T, U> + where + T: Stream, + U: Stream, + { + Merge { + a: Fuse::new(a), + b: Fuse::new(b), + a_first: true, + } + } +} + +impl<T, U> Stream for Merge<T, U> +where + T: Stream, + U: Stream<Item = T::Item>, +{ + type Item = T::Item; + + fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T::Item>> { + let me = self.project(); + let a_first = *me.a_first; + + // Toggle the flag + *me.a_first = !a_first; + + if a_first { + poll_next(me.a, me.b, cx) + } else { + poll_next(me.b, me.a, cx) + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + super::merge_size_hints(self.a.size_hint(), self.b.size_hint()) + } +} + +fn poll_next<T, U>( + first: Pin<&mut T>, + second: Pin<&mut U>, + cx: &mut Context<'_>, +) -> Poll<Option<T::Item>> +where + T: Stream, + U: Stream<Item = T::Item>, +{ + use Poll::*; + + let mut done = true; + + match first.poll_next(cx) { + Ready(Some(val)) => return Ready(Some(val)), + Ready(None) => {} + Pending => done = false, + } + + match second.poll_next(cx) { + Ready(Some(val)) => return Ready(Some(val)), + Ready(None) => {} + Pending => done = false, + } + + if done { + Ready(None) + } else { + Pending + } +} diff --git a/src/stream_ext/next.rs b/src/stream_ext/next.rs new file mode 100644 index 0000000..175490c --- /dev/null +++ b/src/stream_ext/next.rs @@ -0,0 +1,37 @@ +use crate::Stream; + +use core::future::Future; +use core::marker::PhantomPinned; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Future for the [`next`](super::StreamExt::next) method. + #[derive(Debug)] + #[must_use = "futures do nothing unless you `.await` or poll them"] + pub struct Next<'a, St: ?Sized> { + stream: &'a mut St, + // Make this future `!Unpin` for compatibility with async trait methods. + #[pin] + _pin: PhantomPinned, + } +} + +impl<'a, St: ?Sized> Next<'a, St> { + pub(super) fn new(stream: &'a mut St) -> Self { + Next { + stream, + _pin: PhantomPinned, + } + } +} + +impl<St: ?Sized + Stream + Unpin> Future for Next<'_, St> { + type Output = Option<St::Item>; + + fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { + let me = self.project(); + Pin::new(me.stream).poll_next(cx) + } +} diff --git a/src/stream_ext/skip.rs b/src/stream_ext/skip.rs new file mode 100644 index 0000000..80a0a0a --- /dev/null +++ b/src/stream_ext/skip.rs @@ -0,0 +1,63 @@ +use crate::Stream; + +use core::fmt; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Stream for the [`skip`](super::StreamExt::skip) method. + #[must_use = "streams do nothing unless polled"] + pub struct Skip<St> { + #[pin] + stream: St, + remaining: usize, + } +} + +impl<St> fmt::Debug for Skip<St> +where + St: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("Skip") + .field("stream", &self.stream) + .finish() + } +} + +impl<St> Skip<St> { + pub(super) fn new(stream: St, remaining: usize) -> Self { + Self { stream, remaining } + } +} + +impl<St> Stream for Skip<St> +where + St: Stream, +{ + type Item = St::Item; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + loop { + match ready!(self.as_mut().project().stream.poll_next(cx)) { + Some(e) => { + if self.remaining == 0 { + return Poll::Ready(Some(e)); + } + *self.as_mut().project().remaining -= 1; + } + None => return Poll::Ready(None), + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let (lower, upper) = self.stream.size_hint(); + + let lower = lower.saturating_sub(self.remaining); + let upper = upper.map(|x| x.saturating_sub(self.remaining)); + + (lower, upper) + } +} diff --git a/src/stream_ext/skip_while.rs b/src/stream_ext/skip_while.rs new file mode 100644 index 0000000..985a926 --- /dev/null +++ b/src/stream_ext/skip_while.rs @@ -0,0 +1,73 @@ +use crate::Stream; + +use core::fmt; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Stream for the [`skip_while`](super::StreamExt::skip_while) method. + #[must_use = "streams do nothing unless polled"] + pub struct SkipWhile<St, F> { + #[pin] + stream: St, + predicate: Option<F>, + } +} + +impl<St, F> fmt::Debug for SkipWhile<St, F> +where + St: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("SkipWhile") + .field("stream", &self.stream) + .finish() + } +} + +impl<St, F> SkipWhile<St, F> { + pub(super) fn new(stream: St, predicate: F) -> Self { + Self { + stream, + predicate: Some(predicate), + } + } +} + +impl<St, F> Stream for SkipWhile<St, F> +where + St: Stream, + F: FnMut(&St::Item) -> bool, +{ + type Item = St::Item; + + fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + let mut this = self.project(); + if let Some(predicate) = this.predicate { + loop { + match ready!(this.stream.as_mut().poll_next(cx)) { + Some(item) => { + if !(predicate)(&item) { + *this.predicate = None; + return Poll::Ready(Some(item)); + } + } + None => return Poll::Ready(None), + } + } + } else { + this.stream.poll_next(cx) + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let (lower, upper) = self.stream.size_hint(); + + if self.predicate.is_some() { + return (0, upper); + } + + (lower, upper) + } +} diff --git a/src/stream_ext/take.rs b/src/stream_ext/take.rs new file mode 100644 index 0000000..c75648f --- /dev/null +++ b/src/stream_ext/take.rs @@ -0,0 +1,76 @@ +use crate::Stream; + +use core::cmp; +use core::fmt; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Stream for the [`take`](super::StreamExt::take) method. + #[must_use = "streams do nothing unless polled"] + pub struct Take<St> { + #[pin] + stream: St, + remaining: usize, + } +} + +impl<St> fmt::Debug for Take<St> +where + St: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("Take") + .field("stream", &self.stream) + .finish() + } +} + +impl<St> Take<St> { + pub(super) fn new(stream: St, remaining: usize) -> Self { + Self { stream, remaining } + } +} + +impl<St> Stream for Take<St> +where + St: Stream, +{ + type Item = St::Item; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + if *self.as_mut().project().remaining > 0 { + self.as_mut().project().stream.poll_next(cx).map(|ready| { + match &ready { + Some(_) => { + *self.as_mut().project().remaining -= 1; + } + None => { + *self.as_mut().project().remaining = 0; + } + } + ready + }) + } else { + Poll::Ready(None) + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + if self.remaining == 0 { + return (0, Some(0)); + } + + let (lower, upper) = self.stream.size_hint(); + + let lower = cmp::min(lower, self.remaining as usize); + + let upper = match upper { + Some(x) if x < self.remaining as usize => Some(x), + _ => Some(self.remaining as usize), + }; + + (lower, upper) + } +} diff --git a/src/stream_ext/take_while.rs b/src/stream_ext/take_while.rs new file mode 100644 index 0000000..5ce4dd9 --- /dev/null +++ b/src/stream_ext/take_while.rs @@ -0,0 +1,79 @@ +use crate::Stream; + +use core::fmt; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Stream for the [`take_while`](super::StreamExt::take_while) method. + #[must_use = "streams do nothing unless polled"] + pub struct TakeWhile<St, F> { + #[pin] + stream: St, + predicate: F, + done: bool, + } +} + +impl<St, F> fmt::Debug for TakeWhile<St, F> +where + St: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("TakeWhile") + .field("stream", &self.stream) + .field("done", &self.done) + .finish() + } +} + +impl<St, F> TakeWhile<St, F> { + pub(super) fn new(stream: St, predicate: F) -> Self { + Self { + stream, + predicate, + done: false, + } + } +} + +impl<St, F> Stream for TakeWhile<St, F> +where + St: Stream, + F: FnMut(&St::Item) -> bool, +{ + type Item = St::Item; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + if !*self.as_mut().project().done { + self.as_mut().project().stream.poll_next(cx).map(|ready| { + let ready = ready.and_then(|item| { + if !(self.as_mut().project().predicate)(&item) { + None + } else { + Some(item) + } + }); + + if ready.is_none() { + *self.as_mut().project().done = true; + } + + ready + }) + } else { + Poll::Ready(None) + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + if self.done { + return (0, Some(0)); + } + + let (_, upper) = self.stream.size_hint(); + + (0, upper) + } +} diff --git a/src/stream_ext/throttle.rs b/src/stream_ext/throttle.rs new file mode 100644 index 0000000..99f3e0e --- /dev/null +++ b/src/stream_ext/throttle.rs @@ -0,0 +1,97 @@ +//! Slow down a stream by enforcing a delay between items. + +use crate::Stream; +use tokio::time::{Duration, Instant, Sleep}; + +use std::future::Future; +use std::marker::Unpin; +use std::pin::Pin; +use std::task::{self, Poll}; + +use pin_project_lite::pin_project; + +pub(super) fn throttle<T>(duration: Duration, stream: T) -> Throttle<T> +where + T: Stream, +{ + Throttle { + delay: tokio::time::sleep_until(Instant::now() + duration), + duration, + has_delayed: true, + stream, + } +} + +pin_project! { + /// Stream for the [`throttle`](throttle) function. + #[derive(Debug)] + #[must_use = "streams do nothing unless polled"] + pub struct Throttle<T> { + #[pin] + delay: Sleep, + duration: Duration, + + // Set to true when `delay` has returned ready, but `stream` hasn't. + has_delayed: bool, + + // The stream to throttle + #[pin] + stream: T, + } +} + +// XXX: are these safe if `T: !Unpin`? +impl<T: Unpin> Throttle<T> { + /// Acquires a reference to the underlying stream that this combinator is + /// pulling from. + pub fn get_ref(&self) -> &T { + &self.stream + } + + /// Acquires a mutable reference to the underlying stream that this combinator + /// is pulling from. + /// + /// Note that care must be taken to avoid tampering with the state of the stream + /// which may otherwise confuse this combinator. + pub fn get_mut(&mut self) -> &mut T { + &mut self.stream + } + + /// Consumes this combinator, returning the underlying stream. + /// + /// Note that this may discard intermediate state of this combinator, so care + /// should be taken to avoid losing resources when this is called. + pub fn into_inner(self) -> T { + self.stream + } +} + +impl<T: Stream> Stream for Throttle<T> { + type Item = T::Item; + + fn poll_next(self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Option<Self::Item>> { + let mut me = self.project(); + let dur = *me.duration; + + if !*me.has_delayed && !is_zero(dur) { + ready!(me.delay.as_mut().poll(cx)); + *me.has_delayed = true; + } + + let value = ready!(me.stream.poll_next(cx)); + + if value.is_some() { + if !is_zero(dur) { + me.delay.reset(Instant::now() + dur); + } + + *me.has_delayed = false; + } + + Poll::Ready(value) + } +} + +fn is_zero(dur: Duration) -> bool { + dur == Duration::from_millis(0) +} diff --git a/src/stream_ext/timeout.rs b/src/stream_ext/timeout.rs new file mode 100644 index 0000000..de17dc0 --- /dev/null +++ b/src/stream_ext/timeout.rs @@ -0,0 +1,96 @@ +use crate::stream_ext::Fuse; +use crate::Stream; +use tokio::time::{Instant, Sleep}; + +use core::future::Future; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; +use std::fmt; +use std::time::Duration; + +pin_project! { + /// Stream returned by the [`timeout`](super::StreamExt::timeout) method. + #[must_use = "streams do nothing unless polled"] + #[derive(Debug)] + pub struct Timeout<S> { + #[pin] + stream: Fuse<S>, + #[pin] + deadline: Sleep, + duration: Duration, + poll_deadline: bool, + } +} + +/// Error returned by `Timeout`. +#[derive(Debug, PartialEq)] +pub struct Elapsed(()); + +impl<S: Stream> Timeout<S> { + pub(super) fn new(stream: S, duration: Duration) -> Self { + let next = Instant::now() + duration; + let deadline = tokio::time::sleep_until(next); + + Timeout { + stream: Fuse::new(stream), + deadline, + duration, + poll_deadline: true, + } + } +} + +impl<S: Stream> Stream for Timeout<S> { + type Item = Result<S::Item, Elapsed>; + + fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + let me = self.project(); + + match me.stream.poll_next(cx) { + Poll::Ready(v) => { + if v.is_some() { + let next = Instant::now() + *me.duration; + me.deadline.reset(next); + *me.poll_deadline = true; + } + return Poll::Ready(v.map(Ok)); + } + Poll::Pending => {} + }; + + if *me.poll_deadline { + ready!(me.deadline.poll(cx)); + *me.poll_deadline = false; + return Poll::Ready(Some(Err(Elapsed::new()))); + } + + Poll::Pending + } + + fn size_hint(&self) -> (usize, Option<usize>) { + self.stream.size_hint() + } +} + +// ===== impl Elapsed ===== + +impl Elapsed { + pub(crate) fn new() -> Self { + Elapsed(()) + } +} + +impl fmt::Display for Elapsed { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + "deadline has elapsed".fmt(fmt) + } +} + +impl std::error::Error for Elapsed {} + +impl From<Elapsed> for std::io::Error { + fn from(_err: Elapsed) -> std::io::Error { + std::io::ErrorKind::TimedOut.into() + } +} diff --git a/src/stream_ext/try_next.rs b/src/stream_ext/try_next.rs new file mode 100644 index 0000000..af27d87 --- /dev/null +++ b/src/stream_ext/try_next.rs @@ -0,0 +1,39 @@ +use crate::stream_ext::Next; +use crate::Stream; + +use core::future::Future; +use core::marker::PhantomPinned; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Future for the [`try_next`](super::StreamExt::try_next) method. + #[derive(Debug)] + #[must_use = "futures do nothing unless you `.await` or poll them"] + pub struct TryNext<'a, St: ?Sized> { + #[pin] + inner: Next<'a, St>, + // Make this future `!Unpin` for compatibility with async trait methods. + #[pin] + _pin: PhantomPinned, + } +} + +impl<'a, St: ?Sized> TryNext<'a, St> { + pub(super) fn new(stream: &'a mut St) -> Self { + Self { + inner: Next::new(stream), + _pin: PhantomPinned, + } + } +} + +impl<T, E, St: ?Sized + Stream<Item = Result<T, E>> + Unpin> Future for TryNext<'_, St> { + type Output = Result<Option<T>, E>; + + fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { + let me = self.project(); + me.inner.poll(cx).map(Option::transpose) + } +} diff --git a/src/stream_map.rs b/src/stream_map.rs new file mode 100644 index 0000000..85b60cf --- /dev/null +++ b/src/stream_map.rs @@ -0,0 +1,664 @@ +use crate::Stream; + +use std::borrow::Borrow; +use std::hash::Hash; +use std::pin::Pin; +use std::task::{Context, Poll}; + +/// Combine many streams into one, indexing each source stream with a unique +/// key. +/// +/// `StreamMap` is similar to [`StreamExt::merge`] in that it combines source +/// streams into a single merged stream that yields values in the order that +/// they arrive from the source streams. However, `StreamMap` has a lot more +/// flexibility in usage patterns. +/// +/// `StreamMap` can: +/// +/// * Merge an arbitrary number of streams. +/// * Track which source stream the value was received from. +/// * Handle inserting and removing streams from the set of managed streams at +/// any point during iteration. +/// +/// All source streams held by `StreamMap` are indexed using a key. This key is +/// included with the value when a source stream yields a value. The key is also +/// used to remove the stream from the `StreamMap` before the stream has +/// completed streaming. +/// +/// # `Unpin` +/// +/// Because the `StreamMap` API moves streams during runtime, both streams and +/// keys must be `Unpin`. In order to insert a `!Unpin` stream into a +/// `StreamMap`, use [`pin!`] to pin the stream to the stack or [`Box::pin`] to +/// pin the stream in the heap. +/// +/// # Implementation +/// +/// `StreamMap` is backed by a `Vec<(K, V)>`. There is no guarantee that this +/// internal implementation detail will persist in future versions, but it is +/// important to know the runtime implications. In general, `StreamMap` works +/// best with a "smallish" number of streams as all entries are scanned on +/// insert, remove, and polling. In cases where a large number of streams need +/// to be merged, it may be advisable to use tasks sending values on a shared +/// [`mpsc`] channel. +/// +/// [`StreamExt::merge`]: crate::StreamExt::merge +/// [`mpsc`]: https://docs.rs/tokio/1.0/tokio/sync/mpsc/index.html +/// [`pin!`]: https://docs.rs/tokio/1.0/tokio/macro.pin.html +/// [`Box::pin`]: std::boxed::Box::pin +/// +/// # Examples +/// +/// Merging two streams, then remove them after receiving the first value +/// +/// ``` +/// use tokio_stream::{StreamExt, StreamMap, Stream}; +/// use tokio::sync::mpsc; +/// use std::pin::Pin; +/// +/// #[tokio::main] +/// async fn main() { +/// let (tx1, mut rx1) = mpsc::channel::<usize>(10); +/// let (tx2, mut rx2) = mpsc::channel::<usize>(10); +/// +/// // Convert the channels to a `Stream`. +/// let rx1 = Box::pin(async_stream::stream! { +/// while let Some(item) = rx1.recv().await { +/// yield item; +/// } +/// }) as Pin<Box<dyn Stream<Item = usize> + Send>>; +/// +/// let rx2 = Box::pin(async_stream::stream! { +/// while let Some(item) = rx2.recv().await { +/// yield item; +/// } +/// }) as Pin<Box<dyn Stream<Item = usize> + Send>>; +/// +/// tokio::spawn(async move { +/// tx1.send(1).await.unwrap(); +/// +/// // This value will never be received. The send may or may not return +/// // `Err` depending on if the remote end closed first or not. +/// let _ = tx1.send(2).await; +/// }); +/// +/// tokio::spawn(async move { +/// tx2.send(3).await.unwrap(); +/// let _ = tx2.send(4).await; +/// }); +/// +/// let mut map = StreamMap::new(); +/// +/// // Insert both streams +/// map.insert("one", rx1); +/// map.insert("two", rx2); +/// +/// // Read twice +/// for _ in 0..2 { +/// let (key, val) = map.next().await.unwrap(); +/// +/// if key == "one" { +/// assert_eq!(val, 1); +/// } else { +/// assert_eq!(val, 3); +/// } +/// +/// // Remove the stream to prevent reading the next value +/// map.remove(key); +/// } +/// } +/// ``` +/// +/// This example models a read-only client to a chat system with channels. The +/// client sends commands to join and leave channels. `StreamMap` is used to +/// manage active channel subscriptions. +/// +/// For simplicity, messages are displayed with `println!`, but they could be +/// sent to the client over a socket. +/// +/// ```no_run +/// use tokio_stream::{Stream, StreamExt, StreamMap}; +/// +/// enum Command { +/// Join(String), +/// Leave(String), +/// } +/// +/// fn commands() -> impl Stream<Item = Command> { +/// // Streams in user commands by parsing `stdin`. +/// # tokio_stream::pending() +/// } +/// +/// // Join a channel, returns a stream of messages received on the channel. +/// fn join(channel: &str) -> impl Stream<Item = String> + Unpin { +/// // left as an exercise to the reader +/// # tokio_stream::pending() +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// let mut channels = StreamMap::new(); +/// +/// // Input commands (join / leave channels). +/// let cmds = commands(); +/// tokio::pin!(cmds); +/// +/// loop { +/// tokio::select! { +/// Some(cmd) = cmds.next() => { +/// match cmd { +/// Command::Join(chan) => { +/// // Join the channel and add it to the `channels` +/// // stream map +/// let msgs = join(&chan); +/// channels.insert(chan, msgs); +/// } +/// Command::Leave(chan) => { +/// channels.remove(&chan); +/// } +/// } +/// } +/// Some((chan, msg)) = channels.next() => { +/// // Received a message, display it on stdout with the channel +/// // it originated from. +/// println!("{}: {}", chan, msg); +/// } +/// // Both the `commands` stream and the `channels` stream are +/// // complete. There is no more work to do, so leave the loop. +/// else => break, +/// } +/// } +/// } +/// ``` +#[derive(Debug)] +pub struct StreamMap<K, V> { + /// Streams stored in the map + entries: Vec<(K, V)>, +} + +impl<K, V> StreamMap<K, V> { + /// An iterator visiting all key-value pairs in arbitrary order. + /// + /// The iterator element type is &'a (K, V). + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, pending}; + /// + /// let mut map = StreamMap::new(); + /// + /// map.insert("a", pending::<i32>()); + /// map.insert("b", pending()); + /// map.insert("c", pending()); + /// + /// for (key, stream) in map.iter() { + /// println!("({}, {:?})", key, stream); + /// } + /// ``` + pub fn iter(&self) -> impl Iterator<Item = &(K, V)> { + self.entries.iter() + } + + /// An iterator visiting all key-value pairs mutably in arbitrary order. + /// + /// The iterator element type is &'a mut (K, V). + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, pending}; + /// + /// let mut map = StreamMap::new(); + /// + /// map.insert("a", pending::<i32>()); + /// map.insert("b", pending()); + /// map.insert("c", pending()); + /// + /// for (key, stream) in map.iter_mut() { + /// println!("({}, {:?})", key, stream); + /// } + /// ``` + pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut (K, V)> { + self.entries.iter_mut() + } + + /// Creates an empty `StreamMap`. + /// + /// The stream map is initially created with a capacity of `0`, so it will + /// not allocate until it is first inserted into. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, Pending}; + /// + /// let map: StreamMap<&str, Pending<()>> = StreamMap::new(); + /// ``` + pub fn new() -> StreamMap<K, V> { + StreamMap { entries: vec![] } + } + + /// Creates an empty `StreamMap` with the specified capacity. + /// + /// The stream map will be able to hold at least `capacity` elements without + /// reallocating. If `capacity` is 0, the stream map will not allocate. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, Pending}; + /// + /// let map: StreamMap<&str, Pending<()>> = StreamMap::with_capacity(10); + /// ``` + pub fn with_capacity(capacity: usize) -> StreamMap<K, V> { + StreamMap { + entries: Vec::with_capacity(capacity), + } + } + + /// Returns an iterator visiting all keys in arbitrary order. + /// + /// The iterator element type is &'a K. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, pending}; + /// + /// let mut map = StreamMap::new(); + /// + /// map.insert("a", pending::<i32>()); + /// map.insert("b", pending()); + /// map.insert("c", pending()); + /// + /// for key in map.keys() { + /// println!("{}", key); + /// } + /// ``` + pub fn keys(&self) -> impl Iterator<Item = &K> { + self.iter().map(|(k, _)| k) + } + + /// An iterator visiting all values in arbitrary order. + /// + /// The iterator element type is &'a V. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, pending}; + /// + /// let mut map = StreamMap::new(); + /// + /// map.insert("a", pending::<i32>()); + /// map.insert("b", pending()); + /// map.insert("c", pending()); + /// + /// for stream in map.values() { + /// println!("{:?}", stream); + /// } + /// ``` + pub fn values(&self) -> impl Iterator<Item = &V> { + self.iter().map(|(_, v)| v) + } + + /// An iterator visiting all values mutably in arbitrary order. + /// + /// The iterator element type is &'a mut V. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, pending}; + /// + /// let mut map = StreamMap::new(); + /// + /// map.insert("a", pending::<i32>()); + /// map.insert("b", pending()); + /// map.insert("c", pending()); + /// + /// for stream in map.values_mut() { + /// println!("{:?}", stream); + /// } + /// ``` + pub fn values_mut(&mut self) -> impl Iterator<Item = &mut V> { + self.iter_mut().map(|(_, v)| v) + } + + /// Returns the number of streams the map can hold without reallocating. + /// + /// This number is a lower bound; the `StreamMap` might be able to hold + /// more, but is guaranteed to be able to hold at least this many. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, Pending}; + /// + /// let map: StreamMap<i32, Pending<()>> = StreamMap::with_capacity(100); + /// assert!(map.capacity() >= 100); + /// ``` + pub fn capacity(&self) -> usize { + self.entries.capacity() + } + + /// Returns the number of streams in the map. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, pending}; + /// + /// let mut a = StreamMap::new(); + /// assert_eq!(a.len(), 0); + /// a.insert(1, pending::<i32>()); + /// assert_eq!(a.len(), 1); + /// ``` + pub fn len(&self) -> usize { + self.entries.len() + } + + /// Returns `true` if the map contains no elements. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut a = HashMap::new(); + /// assert!(a.is_empty()); + /// a.insert(1, "a"); + /// assert!(!a.is_empty()); + /// ``` + pub fn is_empty(&self) -> bool { + self.entries.is_empty() + } + + /// Clears the map, removing all key-stream pairs. Keeps the allocated + /// memory for reuse. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, pending}; + /// + /// let mut a = StreamMap::new(); + /// a.insert(1, pending::<i32>()); + /// a.clear(); + /// assert!(a.is_empty()); + /// ``` + pub fn clear(&mut self) { + self.entries.clear(); + } + + /// Insert a key-stream pair into the map. + /// + /// If the map did not have this key present, `None` is returned. + /// + /// If the map did have this key present, the new `stream` replaces the old + /// one and the old stream is returned. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, pending}; + /// + /// let mut map = StreamMap::new(); + /// + /// assert!(map.insert(37, pending::<i32>()).is_none()); + /// assert!(!map.is_empty()); + /// + /// map.insert(37, pending()); + /// assert!(map.insert(37, pending()).is_some()); + /// ``` + pub fn insert(&mut self, k: K, stream: V) -> Option<V> + where + K: Hash + Eq, + { + let ret = self.remove(&k); + self.entries.push((k, stream)); + + ret + } + + /// Removes a key from the map, returning the stream at the key if the key was previously in the map. + /// + /// The key may be any borrowed form of the map's key type, but `Hash` and + /// `Eq` on the borrowed form must match those for the key type. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, pending}; + /// + /// let mut map = StreamMap::new(); + /// map.insert(1, pending::<i32>()); + /// assert!(map.remove(&1).is_some()); + /// assert!(map.remove(&1).is_none()); + /// ``` + pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V> + where + K: Borrow<Q>, + Q: Hash + Eq, + { + for i in 0..self.entries.len() { + if self.entries[i].0.borrow() == k { + return Some(self.entries.swap_remove(i).1); + } + } + + None + } + + /// Returns `true` if the map contains a stream for the specified key. + /// + /// The key may be any borrowed form of the map's key type, but `Hash` and + /// `Eq` on the borrowed form must match those for the key type. + /// + /// # Examples + /// + /// ``` + /// use tokio_stream::{StreamMap, pending}; + /// + /// let mut map = StreamMap::new(); + /// map.insert(1, pending::<i32>()); + /// assert_eq!(map.contains_key(&1), true); + /// assert_eq!(map.contains_key(&2), false); + /// ``` + pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool + where + K: Borrow<Q>, + Q: Hash + Eq, + { + for i in 0..self.entries.len() { + if self.entries[i].0.borrow() == k { + return true; + } + } + + false + } +} + +impl<K, V> StreamMap<K, V> +where + K: Unpin, + V: Stream + Unpin, +{ + /// Polls the next value, includes the vec entry index + fn poll_next_entry(&mut self, cx: &mut Context<'_>) -> Poll<Option<(usize, V::Item)>> { + use Poll::*; + + let start = self::rand::thread_rng_n(self.entries.len() as u32) as usize; + let mut idx = start; + + for _ in 0..self.entries.len() { + let (_, stream) = &mut self.entries[idx]; + + match Pin::new(stream).poll_next(cx) { + Ready(Some(val)) => return Ready(Some((idx, val))), + Ready(None) => { + // Remove the entry + self.entries.swap_remove(idx); + + // Check if this was the last entry, if so the cursor needs + // to wrap + if idx == self.entries.len() { + idx = 0; + } else if idx < start && start <= self.entries.len() { + // The stream being swapped into the current index has + // already been polled, so skip it. + idx = idx.wrapping_add(1) % self.entries.len(); + } + } + Pending => { + idx = idx.wrapping_add(1) % self.entries.len(); + } + } + } + + // If the map is empty, then the stream is complete. + if self.entries.is_empty() { + Ready(None) + } else { + Pending + } + } +} + +impl<K, V> Default for StreamMap<K, V> { + fn default() -> Self { + Self::new() + } +} + +impl<K, V> Stream for StreamMap<K, V> +where + K: Clone + Unpin, + V: Stream + Unpin, +{ + type Item = (K, V::Item); + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + if let Some((idx, val)) = ready!(self.poll_next_entry(cx)) { + let key = self.entries[idx].0.clone(); + Poll::Ready(Some((key, val))) + } else { + Poll::Ready(None) + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let mut ret = (0, Some(0)); + + for (_, stream) in &self.entries { + let hint = stream.size_hint(); + + ret.0 += hint.0; + + match (ret.1, hint.1) { + (Some(a), Some(b)) => ret.1 = Some(a + b), + (Some(_), None) => ret.1 = None, + _ => {} + } + } + + ret + } +} + +mod rand { + use std::cell::Cell; + + mod loom { + #[cfg(not(loom))] + pub(crate) mod rand { + use std::collections::hash_map::RandomState; + use std::hash::{BuildHasher, Hash, Hasher}; + use std::sync::atomic::AtomicU32; + use std::sync::atomic::Ordering::Relaxed; + + static COUNTER: AtomicU32 = AtomicU32::new(1); + + pub(crate) fn seed() -> u64 { + let rand_state = RandomState::new(); + + let mut hasher = rand_state.build_hasher(); + + // Hash some unique-ish data to generate some new state + COUNTER.fetch_add(1, Relaxed).hash(&mut hasher); + + // Get the seed + hasher.finish() + } + } + + #[cfg(loom)] + pub(crate) mod rand { + pub(crate) fn seed() -> u64 { + 1 + } + } + } + + /// Fast random number generate + /// + /// Implement xorshift64+: 2 32-bit xorshift sequences added together. + /// Shift triplet [17,7,16] was calculated as indicated in Marsaglia's + /// Xorshift paper: https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf + /// This generator passes the SmallCrush suite, part of TestU01 framework: + /// http://simul.iro.umontreal.ca/testu01/tu01.html + #[derive(Debug)] + pub(crate) struct FastRand { + one: Cell<u32>, + two: Cell<u32>, + } + + impl FastRand { + /// Initialize a new, thread-local, fast random number generator. + pub(crate) fn new(seed: u64) -> FastRand { + let one = (seed >> 32) as u32; + let mut two = seed as u32; + + if two == 0 { + // This value cannot be zero + two = 1; + } + + FastRand { + one: Cell::new(one), + two: Cell::new(two), + } + } + + pub(crate) fn fastrand_n(&self, n: u32) -> u32 { + // This is similar to fastrand() % n, but faster. + // See https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/ + let mul = (self.fastrand() as u64).wrapping_mul(n as u64); + (mul >> 32) as u32 + } + + fn fastrand(&self) -> u32 { + let mut s1 = self.one.get(); + let s0 = self.two.get(); + + s1 ^= s1 << 17; + s1 = s1 ^ s0 ^ s1 >> 7 ^ s0 >> 16; + + self.one.set(s0); + self.two.set(s1); + + s0.wrapping_add(s1) + } + } + + // Used by `StreamMap` + pub(crate) fn thread_rng_n(n: u32) -> u32 { + thread_local! { + static THREAD_RNG: FastRand = FastRand::new(loom::rand::seed()); + } + + THREAD_RNG.with(|rng| rng.fastrand_n(n)) + } +} diff --git a/src/wrappers.rs b/src/wrappers.rs new file mode 100644 index 0000000..c0ffb23 --- /dev/null +++ b/src/wrappers.rs @@ -0,0 +1,35 @@ +//! Wrappers for Tokio types that implement `Stream`. + +mod mpsc_bounded; +pub use mpsc_bounded::ReceiverStream; + +mod mpsc_unbounded; +pub use mpsc_unbounded::UnboundedReceiverStream; + +cfg_time! { + mod interval; + pub use interval::IntervalStream; +} + +cfg_net! { + mod tcp_listener; + pub use tcp_listener::TcpListenerStream; + + #[cfg(unix)] + mod unix_listener; + #[cfg(unix)] + pub use unix_listener::UnixListenerStream; +} + +cfg_io_util! { + mod split; + pub use split::SplitStream; + + mod lines; + pub use lines::LinesStream; +} + +cfg_fs! { + mod read_dir; + pub use read_dir::ReadDirStream; +} diff --git a/src/wrappers/interval.rs b/src/wrappers/interval.rs new file mode 100644 index 0000000..2bf0194 --- /dev/null +++ b/src/wrappers/interval.rs @@ -0,0 +1,50 @@ +use crate::Stream; +use std::pin::Pin; +use std::task::{Context, Poll}; +use tokio::time::{Instant, Interval}; + +/// A wrapper around [`Interval`] that implements [`Stream`]. +/// +/// [`Interval`]: struct@tokio::time::Interval +/// [`Stream`]: trait@crate::Stream +#[derive(Debug)] +#[cfg_attr(docsrs, doc(cfg(feature = "time")))] +pub struct IntervalStream { + inner: Interval, +} + +impl IntervalStream { + /// Create a new `IntervalStream`. + pub fn new(interval: Interval) -> Self { + Self { inner: interval } + } + + /// Get back the inner `Interval`. + pub fn into_inner(self) -> Interval { + self.inner + } +} + +impl Stream for IntervalStream { + type Item = Instant; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Instant>> { + self.inner.poll_tick(cx).map(Some) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (std::usize::MAX, None) + } +} + +impl AsRef<Interval> for IntervalStream { + fn as_ref(&self) -> &Interval { + &self.inner + } +} + +impl AsMut<Interval> for IntervalStream { + fn as_mut(&mut self) -> &mut Interval { + &mut self.inner + } +} diff --git a/src/wrappers/lines.rs b/src/wrappers/lines.rs new file mode 100644 index 0000000..ad3c253 --- /dev/null +++ b/src/wrappers/lines.rs @@ -0,0 +1,60 @@ +use crate::Stream; +use pin_project_lite::pin_project; +use std::io; +use std::pin::Pin; +use std::task::{Context, Poll}; +use tokio::io::{AsyncBufRead, Lines}; + +pin_project! { + /// A wrapper around [`tokio::io::Lines`] that implements [`Stream`]. + /// + /// [`tokio::io::Lines`]: struct@tokio::io::Lines + /// [`Stream`]: trait@crate::Stream + #[derive(Debug)] + #[cfg_attr(docsrs, doc(cfg(feature = "io-util")))] + pub struct LinesStream<R> { + #[pin] + inner: Lines<R>, + } +} + +impl<R> LinesStream<R> { + /// Create a new `LinesStream`. + pub fn new(lines: Lines<R>) -> Self { + Self { inner: lines } + } + + /// Get back the inner `Lines`. + pub fn into_inner(self) -> Lines<R> { + self.inner + } + + /// Obtain a pinned reference to the inner `Lines<R>`. + #[allow(clippy::wrong_self_convention)] // https://github.com/rust-lang/rust-clippy/issues/4546 + pub fn as_pin_mut(self: Pin<&mut Self>) -> Pin<&mut Lines<R>> { + self.project().inner + } +} + +impl<R: AsyncBufRead> Stream for LinesStream<R> { + type Item = io::Result<String>; + + fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + self.project() + .inner + .poll_next_line(cx) + .map(Result::transpose) + } +} + +impl<R> AsRef<Lines<R>> for LinesStream<R> { + fn as_ref(&self) -> &Lines<R> { + &self.inner + } +} + +impl<R> AsMut<Lines<R>> for LinesStream<R> { + fn as_mut(&mut self) -> &mut Lines<R> { + &mut self.inner + } +} diff --git a/src/wrappers/mpsc_bounded.rs b/src/wrappers/mpsc_bounded.rs new file mode 100644 index 0000000..e4f9000 --- /dev/null +++ b/src/wrappers/mpsc_bounded.rs @@ -0,0 +1,59 @@ +use crate::Stream; +use std::pin::Pin; +use std::task::{Context, Poll}; +use tokio::sync::mpsc::Receiver; + +/// A wrapper around [`tokio::sync::mpsc::Receiver`] that implements [`Stream`]. +/// +/// [`tokio::sync::mpsc::Receiver`]: struct@tokio::sync::mpsc::Receiver +/// [`Stream`]: trait@crate::Stream +#[derive(Debug)] +pub struct ReceiverStream<T> { + inner: Receiver<T>, +} + +impl<T> ReceiverStream<T> { + /// Create a new `ReceiverStream`. + pub fn new(recv: Receiver<T>) -> Self { + Self { inner: recv } + } + + /// Get back the inner `Receiver`. + pub fn into_inner(self) -> Receiver<T> { + self.inner + } + + /// Closes the receiving half of a channel without dropping it. + /// + /// This prevents any further messages from being sent on the channel while + /// still enabling the receiver to drain messages that are buffered. Any + /// outstanding [`Permit`] values will still be able to send messages. + /// + /// To guarantee no messages are dropped, after calling `close()`, you must + /// receive all items from the stream until `None` is returned. + /// + /// [`Permit`]: struct@tokio::sync::mpsc::Permit + pub fn close(&mut self) { + self.inner.close() + } +} + +impl<T> Stream for ReceiverStream<T> { + type Item = T; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + self.inner.poll_recv(cx) + } +} + +impl<T> AsRef<Receiver<T>> for ReceiverStream<T> { + fn as_ref(&self) -> &Receiver<T> { + &self.inner + } +} + +impl<T> AsMut<Receiver<T>> for ReceiverStream<T> { + fn as_mut(&mut self) -> &mut Receiver<T> { + &mut self.inner + } +} diff --git a/src/wrappers/mpsc_unbounded.rs b/src/wrappers/mpsc_unbounded.rs new file mode 100644 index 0000000..bc5f40c --- /dev/null +++ b/src/wrappers/mpsc_unbounded.rs @@ -0,0 +1,53 @@ +use crate::Stream; +use std::pin::Pin; +use std::task::{Context, Poll}; +use tokio::sync::mpsc::UnboundedReceiver; + +/// A wrapper around [`tokio::sync::mpsc::UnboundedReceiver`] that implements [`Stream`]. +/// +/// [`tokio::sync::mpsc::UnboundedReceiver`]: struct@tokio::sync::mpsc::UnboundedReceiver +/// [`Stream`]: trait@crate::Stream +#[derive(Debug)] +pub struct UnboundedReceiverStream<T> { + inner: UnboundedReceiver<T>, +} + +impl<T> UnboundedReceiverStream<T> { + /// Create a new `UnboundedReceiverStream`. + pub fn new(recv: UnboundedReceiver<T>) -> Self { + Self { inner: recv } + } + + /// Get back the inner `UnboundedReceiver`. + pub fn into_inner(self) -> UnboundedReceiver<T> { + self.inner + } + + /// Closes the receiving half of a channel without dropping it. + /// + /// This prevents any further messages from being sent on the channel while + /// still enabling the receiver to drain messages that are buffered. + pub fn close(&mut self) { + self.inner.close() + } +} + +impl<T> Stream for UnboundedReceiverStream<T> { + type Item = T; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + self.inner.poll_recv(cx) + } +} + +impl<T> AsRef<UnboundedReceiver<T>> for UnboundedReceiverStream<T> { + fn as_ref(&self) -> &UnboundedReceiver<T> { + &self.inner + } +} + +impl<T> AsMut<UnboundedReceiver<T>> for UnboundedReceiverStream<T> { + fn as_mut(&mut self) -> &mut UnboundedReceiver<T> { + &mut self.inner + } +} diff --git a/src/wrappers/read_dir.rs b/src/wrappers/read_dir.rs new file mode 100644 index 0000000..b5cf54f --- /dev/null +++ b/src/wrappers/read_dir.rs @@ -0,0 +1,47 @@ +use crate::Stream; +use std::io; +use std::pin::Pin; +use std::task::{Context, Poll}; +use tokio::fs::{DirEntry, ReadDir}; + +/// A wrapper around [`tokio::fs::ReadDir`] that implements [`Stream`]. +/// +/// [`tokio::fs::ReadDir`]: struct@tokio::fs::ReadDir +/// [`Stream`]: trait@crate::Stream +#[derive(Debug)] +#[cfg_attr(docsrs, doc(cfg(feature = "fs")))] +pub struct ReadDirStream { + inner: ReadDir, +} + +impl ReadDirStream { + /// Create a new `ReadDirStream`. + pub fn new(read_dir: ReadDir) -> Self { + Self { inner: read_dir } + } + + /// Get back the inner `ReadDir`. + pub fn into_inner(self) -> ReadDir { + self.inner + } +} + +impl Stream for ReadDirStream { + type Item = io::Result<DirEntry>; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + self.inner.poll_next_entry(cx).map(Result::transpose) + } +} + +impl AsRef<ReadDir> for ReadDirStream { + fn as_ref(&self) -> &ReadDir { + &self.inner + } +} + +impl AsMut<ReadDir> for ReadDirStream { + fn as_mut(&mut self) -> &mut ReadDir { + &mut self.inner + } +} diff --git a/src/wrappers/split.rs b/src/wrappers/split.rs new file mode 100644 index 0000000..5a6bb2d --- /dev/null +++ b/src/wrappers/split.rs @@ -0,0 +1,60 @@ +use crate::Stream; +use pin_project_lite::pin_project; +use std::io; +use std::pin::Pin; +use std::task::{Context, Poll}; +use tokio::io::{AsyncBufRead, Split}; + +pin_project! { + /// A wrapper around [`tokio::io::Split`] that implements [`Stream`]. + /// + /// [`tokio::io::Split`]: struct@tokio::io::Split + /// [`Stream`]: trait@crate::Stream + #[derive(Debug)] + #[cfg_attr(docsrs, doc(cfg(feature = "io-util")))] + pub struct SplitStream<R> { + #[pin] + inner: Split<R>, + } +} + +impl<R> SplitStream<R> { + /// Create a new `SplitStream`. + pub fn new(split: Split<R>) -> Self { + Self { inner: split } + } + + /// Get back the inner `Split`. + pub fn into_inner(self) -> Split<R> { + self.inner + } + + /// Obtain a pinned reference to the inner `Split<R>`. + #[allow(clippy::wrong_self_convention)] // https://github.com/rust-lang/rust-clippy/issues/4546 + pub fn as_pin_mut(self: Pin<&mut Self>) -> Pin<&mut Split<R>> { + self.project().inner + } +} + +impl<R: AsyncBufRead> Stream for SplitStream<R> { + type Item = io::Result<Vec<u8>>; + + fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { + self.project() + .inner + .poll_next_segment(cx) + .map(Result::transpose) + } +} + +impl<R> AsRef<Split<R>> for SplitStream<R> { + fn as_ref(&self) -> &Split<R> { + &self.inner + } +} + +impl<R> AsMut<Split<R>> for SplitStream<R> { + fn as_mut(&mut self) -> &mut Split<R> { + &mut self.inner + } +} diff --git a/src/wrappers/tcp_listener.rs b/src/wrappers/tcp_listener.rs new file mode 100644 index 0000000..ce7cb16 --- /dev/null +++ b/src/wrappers/tcp_listener.rs @@ -0,0 +1,54 @@ +use crate::Stream; +use std::io; +use std::pin::Pin; +use std::task::{Context, Poll}; +use tokio::net::{TcpListener, TcpStream}; + +/// A wrapper around [`TcpListener`] that implements [`Stream`]. +/// +/// [`TcpListener`]: struct@tokio::net::TcpListener +/// [`Stream`]: trait@crate::Stream +#[derive(Debug)] +#[cfg_attr(docsrs, doc(cfg(feature = "net")))] +pub struct TcpListenerStream { + inner: TcpListener, +} + +impl TcpListenerStream { + /// Create a new `TcpListenerStream`. + pub fn new(listener: TcpListener) -> Self { + Self { inner: listener } + } + + /// Get back the inner `TcpListener`. + pub fn into_inner(self) -> TcpListener { + self.inner + } +} + +impl Stream for TcpListenerStream { + type Item = io::Result<TcpStream>; + + fn poll_next( + self: Pin<&mut Self>, + cx: &mut Context<'_>, + ) -> Poll<Option<io::Result<TcpStream>>> { + match self.inner.poll_accept(cx) { + Poll::Ready(Ok((stream, _))) => Poll::Ready(Some(Ok(stream))), + Poll::Ready(Err(err)) => Poll::Ready(Some(Err(err))), + Poll::Pending => Poll::Pending, + } + } +} + +impl AsRef<TcpListener> for TcpListenerStream { + fn as_ref(&self) -> &TcpListener { + &self.inner + } +} + +impl AsMut<TcpListener> for TcpListenerStream { + fn as_mut(&mut self) -> &mut TcpListener { + &mut self.inner + } +} diff --git a/src/wrappers/unix_listener.rs b/src/wrappers/unix_listener.rs new file mode 100644 index 0000000..0beba58 --- /dev/null +++ b/src/wrappers/unix_listener.rs @@ -0,0 +1,54 @@ +use crate::Stream; +use std::io; +use std::pin::Pin; +use std::task::{Context, Poll}; +use tokio::net::{UnixListener, UnixStream}; + +/// A wrapper around [`UnixListener`] that implements [`Stream`]. +/// +/// [`UnixListener`]: struct@tokio::net::UnixListener +/// [`Stream`]: trait@crate::Stream +#[derive(Debug)] +#[cfg_attr(docsrs, doc(cfg(all(unix, feature = "net"))))] +pub struct UnixListenerStream { + inner: UnixListener, +} + +impl UnixListenerStream { + /// Create a new `UnixListenerStream`. + pub fn new(listener: UnixListener) -> Self { + Self { inner: listener } + } + + /// Get back the inner `UnixListener`. + pub fn into_inner(self) -> UnixListener { + self.inner + } +} + +impl Stream for UnixListenerStream { + type Item = io::Result<UnixStream>; + + fn poll_next( + self: Pin<&mut Self>, + cx: &mut Context<'_>, + ) -> Poll<Option<io::Result<UnixStream>>> { + match self.inner.poll_accept(cx) { + Poll::Ready(Ok((stream, _))) => Poll::Ready(Some(Ok(stream))), + Poll::Ready(Err(err)) => Poll::Ready(Some(Err(err))), + Poll::Pending => Poll::Pending, + } + } +} + +impl AsRef<UnixListener> for UnixListenerStream { + fn as_ref(&self) -> &UnixListener { + &self.inner + } +} + +impl AsMut<UnixListener> for UnixListenerStream { + fn as_mut(&mut self) -> &mut UnixListener { + &mut self.inner + } +} diff --git a/tests/async_send_sync.rs b/tests/async_send_sync.rs new file mode 100644 index 0000000..c06bebd --- /dev/null +++ b/tests/async_send_sync.rs @@ -0,0 +1,105 @@ +use std::rc::Rc; + +#[allow(dead_code)] +type BoxStream<T> = std::pin::Pin<Box<dyn tokio_stream::Stream<Item = T>>>; + +#[allow(dead_code)] +fn require_send<T: Send>(_t: &T) {} +#[allow(dead_code)] +fn require_sync<T: Sync>(_t: &T) {} +#[allow(dead_code)] +fn require_unpin<T: Unpin>(_t: &T) {} + +#[allow(dead_code)] +struct Invalid; + +trait AmbiguousIfSend<A> { + fn some_item(&self) {} +} +impl<T: ?Sized> AmbiguousIfSend<()> for T {} +impl<T: ?Sized + Send> AmbiguousIfSend<Invalid> for T {} + +trait AmbiguousIfSync<A> { + fn some_item(&self) {} +} +impl<T: ?Sized> AmbiguousIfSync<()> for T {} +impl<T: ?Sized + Sync> AmbiguousIfSync<Invalid> for T {} + +trait AmbiguousIfUnpin<A> { + fn some_item(&self) {} +} +impl<T: ?Sized> AmbiguousIfUnpin<()> for T {} +impl<T: ?Sized + Unpin> AmbiguousIfUnpin<Invalid> for T {} + +macro_rules! into_todo { + ($typ:ty) => {{ + let x: $typ = todo!(); + x + }}; +} + +macro_rules! async_assert_fn { + ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): Send & Sync) => { + #[allow(unreachable_code)] + #[allow(unused_variables)] + const _: fn() = || { + let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* ); + require_send(&f); + require_sync(&f); + }; + }; + ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): Send & !Sync) => { + #[allow(unreachable_code)] + #[allow(unused_variables)] + const _: fn() = || { + let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* ); + require_send(&f); + AmbiguousIfSync::some_item(&f); + }; + }; + ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): !Send & Sync) => { + #[allow(unreachable_code)] + #[allow(unused_variables)] + const _: fn() = || { + let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* ); + AmbiguousIfSend::some_item(&f); + require_sync(&f); + }; + }; + ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): !Send & !Sync) => { + #[allow(unreachable_code)] + #[allow(unused_variables)] + const _: fn() = || { + let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* ); + AmbiguousIfSend::some_item(&f); + AmbiguousIfSync::some_item(&f); + }; + }; + ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): !Unpin) => { + #[allow(unreachable_code)] + #[allow(unused_variables)] + const _: fn() = || { + let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* ); + AmbiguousIfUnpin::some_item(&f); + }; + }; + ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): Unpin) => { + #[allow(unreachable_code)] + #[allow(unused_variables)] + const _: fn() = || { + let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* ); + require_unpin(&f); + }; + }; +} + +async_assert_fn!(tokio_stream::empty<Rc<u8>>(): Send & Sync); +async_assert_fn!(tokio_stream::pending<Rc<u8>>(): Send & Sync); +async_assert_fn!(tokio_stream::iter(std::vec::IntoIter<u8>): Send & Sync); + +async_assert_fn!(tokio_stream::StreamExt::next(&mut BoxStream<()>): !Unpin); +async_assert_fn!(tokio_stream::StreamExt::try_next(&mut BoxStream<Result<(), ()>>): !Unpin); +async_assert_fn!(tokio_stream::StreamExt::all(&mut BoxStream<()>, fn(())->bool): !Unpin); +async_assert_fn!(tokio_stream::StreamExt::any(&mut BoxStream<()>, fn(())->bool): !Unpin); +async_assert_fn!(tokio_stream::StreamExt::fold(&mut BoxStream<()>, (), fn((), ())->()): !Unpin); +async_assert_fn!(tokio_stream::StreamExt::collect<Vec<()>>(&mut BoxStream<()>): !Unpin); diff --git a/tests/stream_chain.rs b/tests/stream_chain.rs new file mode 100644 index 0000000..759de30 --- /dev/null +++ b/tests/stream_chain.rs @@ -0,0 +1,100 @@ +use tokio_stream::{self as stream, Stream, StreamExt}; +use tokio_test::{assert_pending, assert_ready, task}; + +mod support { + pub(crate) mod mpsc; +} + +use support::mpsc; + +#[tokio::test] +async fn basic_usage() { + let one = stream::iter(vec![1, 2, 3]); + let two = stream::iter(vec![4, 5, 6]); + + let mut stream = one.chain(two); + + assert_eq!(stream.size_hint(), (6, Some(6))); + assert_eq!(stream.next().await, Some(1)); + + assert_eq!(stream.size_hint(), (5, Some(5))); + assert_eq!(stream.next().await, Some(2)); + + assert_eq!(stream.size_hint(), (4, Some(4))); + assert_eq!(stream.next().await, Some(3)); + + assert_eq!(stream.size_hint(), (3, Some(3))); + assert_eq!(stream.next().await, Some(4)); + + assert_eq!(stream.size_hint(), (2, Some(2))); + assert_eq!(stream.next().await, Some(5)); + + assert_eq!(stream.size_hint(), (1, Some(1))); + assert_eq!(stream.next().await, Some(6)); + + assert_eq!(stream.size_hint(), (0, Some(0))); + assert_eq!(stream.next().await, None); + + assert_eq!(stream.size_hint(), (0, Some(0))); + assert_eq!(stream.next().await, None); +} + +#[tokio::test] +async fn pending_first() { + let (tx1, rx1) = mpsc::unbounded_channel_stream(); + let (tx2, rx2) = mpsc::unbounded_channel_stream(); + + let mut stream = task::spawn(rx1.chain(rx2)); + assert_eq!(stream.size_hint(), (0, None)); + + assert_pending!(stream.poll_next()); + + tx2.send(2).unwrap(); + assert!(!stream.is_woken()); + + assert_pending!(stream.poll_next()); + + tx1.send(1).unwrap(); + assert!(stream.is_woken()); + assert_eq!(Some(1), assert_ready!(stream.poll_next())); + + assert_pending!(stream.poll_next()); + + drop(tx1); + + assert_eq!(stream.size_hint(), (0, None)); + + assert!(stream.is_woken()); + assert_eq!(Some(2), assert_ready!(stream.poll_next())); + + assert_eq!(stream.size_hint(), (0, None)); + + drop(tx2); + + assert_eq!(stream.size_hint(), (0, None)); + assert_eq!(None, assert_ready!(stream.poll_next())); +} + +#[test] +fn size_overflow() { + struct Monster; + + impl tokio_stream::Stream for Monster { + type Item = (); + fn poll_next( + self: std::pin::Pin<&mut Self>, + _cx: &mut std::task::Context<'_>, + ) -> std::task::Poll<Option<()>> { + panic!() + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (usize::max_value(), Some(usize::max_value())) + } + } + + let m1 = Monster; + let m2 = Monster; + let m = m1.chain(m2); + assert_eq!(m.size_hint(), (usize::max_value(), None)); +} diff --git a/tests/stream_collect.rs b/tests/stream_collect.rs new file mode 100644 index 0000000..07659a1 --- /dev/null +++ b/tests/stream_collect.rs @@ -0,0 +1,146 @@ +use tokio_stream::{self as stream, StreamExt}; +use tokio_test::{assert_pending, assert_ready, assert_ready_err, assert_ready_ok, task}; + +mod support { + pub(crate) mod mpsc; +} + +use support::mpsc; + +#[allow(clippy::let_unit_value)] +#[tokio::test] +async fn empty_unit() { + // Drains the stream. + let mut iter = vec![(), (), ()].into_iter(); + let _: () = stream::iter(&mut iter).collect().await; + assert!(iter.next().is_none()); +} + +#[tokio::test] +async fn empty_vec() { + let coll: Vec<u32> = stream::empty().collect().await; + assert!(coll.is_empty()); +} + +#[tokio::test] +async fn empty_box_slice() { + let coll: Box<[u32]> = stream::empty().collect().await; + assert!(coll.is_empty()); +} + +#[tokio::test] +async fn empty_string() { + let coll: String = stream::empty::<&str>().collect().await; + assert!(coll.is_empty()); +} + +#[tokio::test] +async fn empty_result() { + let coll: Result<Vec<u32>, &str> = stream::empty().collect().await; + assert_eq!(Ok(vec![]), coll); +} + +#[tokio::test] +async fn collect_vec_items() { + let (tx, rx) = mpsc::unbounded_channel_stream(); + let mut fut = task::spawn(rx.collect::<Vec<i32>>()); + + assert_pending!(fut.poll()); + + tx.send(1).unwrap(); + assert!(fut.is_woken()); + assert_pending!(fut.poll()); + + tx.send(2).unwrap(); + assert!(fut.is_woken()); + assert_pending!(fut.poll()); + + drop(tx); + assert!(fut.is_woken()); + let coll = assert_ready!(fut.poll()); + assert_eq!(vec![1, 2], coll); +} + +#[tokio::test] +async fn collect_string_items() { + let (tx, rx) = mpsc::unbounded_channel_stream(); + + let mut fut = task::spawn(rx.collect::<String>()); + + assert_pending!(fut.poll()); + + tx.send("hello ".to_string()).unwrap(); + assert!(fut.is_woken()); + assert_pending!(fut.poll()); + + tx.send("world".to_string()).unwrap(); + assert!(fut.is_woken()); + assert_pending!(fut.poll()); + + drop(tx); + assert!(fut.is_woken()); + let coll = assert_ready!(fut.poll()); + assert_eq!("hello world", coll); +} + +#[tokio::test] +async fn collect_str_items() { + let (tx, rx) = mpsc::unbounded_channel_stream(); + + let mut fut = task::spawn(rx.collect::<String>()); + + assert_pending!(fut.poll()); + + tx.send("hello ").unwrap(); + assert!(fut.is_woken()); + assert_pending!(fut.poll()); + + tx.send("world").unwrap(); + assert!(fut.is_woken()); + assert_pending!(fut.poll()); + + drop(tx); + assert!(fut.is_woken()); + let coll = assert_ready!(fut.poll()); + assert_eq!("hello world", coll); +} + +#[tokio::test] +async fn collect_results_ok() { + let (tx, rx) = mpsc::unbounded_channel_stream(); + + let mut fut = task::spawn(rx.collect::<Result<String, &str>>()); + + assert_pending!(fut.poll()); + + tx.send(Ok("hello ")).unwrap(); + assert!(fut.is_woken()); + assert_pending!(fut.poll()); + + tx.send(Ok("world")).unwrap(); + assert!(fut.is_woken()); + assert_pending!(fut.poll()); + + drop(tx); + assert!(fut.is_woken()); + let coll = assert_ready_ok!(fut.poll()); + assert_eq!("hello world", coll); +} + +#[tokio::test] +async fn collect_results_err() { + let (tx, rx) = mpsc::unbounded_channel_stream(); + + let mut fut = task::spawn(rx.collect::<Result<String, &str>>()); + + assert_pending!(fut.poll()); + + tx.send(Ok("hello ")).unwrap(); + assert!(fut.is_woken()); + assert_pending!(fut.poll()); + + tx.send(Err("oh no")).unwrap(); + assert!(fut.is_woken()); + let err = assert_ready_err!(fut.poll()); + assert_eq!("oh no", err); +} diff --git a/tests/stream_empty.rs b/tests/stream_empty.rs new file mode 100644 index 0000000..c06f5c4 --- /dev/null +++ b/tests/stream_empty.rs @@ -0,0 +1,11 @@ +use tokio_stream::{self as stream, Stream, StreamExt}; + +#[tokio::test] +async fn basic_usage() { + let mut stream = stream::empty::<i32>(); + + for _ in 0..2 { + assert_eq!(stream.size_hint(), (0, Some(0))); + assert_eq!(None, stream.next().await); + } +} diff --git a/tests/stream_fuse.rs b/tests/stream_fuse.rs new file mode 100644 index 0000000..9b6cf05 --- /dev/null +++ b/tests/stream_fuse.rs @@ -0,0 +1,50 @@ +use tokio_stream::{Stream, StreamExt}; + +use std::pin::Pin; +use std::task::{Context, Poll}; + +// a stream which alternates between Some and None +struct Alternate { + state: i32, +} + +impl Stream for Alternate { + type Item = i32; + + fn poll_next(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<i32>> { + let val = self.state; + self.state += 1; + + // if it's even, Some(i32), else None + if val % 2 == 0 { + Poll::Ready(Some(val)) + } else { + Poll::Ready(None) + } + } +} + +#[tokio::test] +async fn basic_usage() { + let mut stream = Alternate { state: 0 }; + + // the stream goes back and forth + assert_eq!(stream.next().await, Some(0)); + assert_eq!(stream.next().await, None); + assert_eq!(stream.next().await, Some(2)); + assert_eq!(stream.next().await, None); + + // however, once it is fused + let mut stream = stream.fuse(); + + assert_eq!(stream.size_hint(), (0, None)); + assert_eq!(stream.next().await, Some(4)); + + assert_eq!(stream.size_hint(), (0, None)); + assert_eq!(stream.next().await, None); + + // it will always return `None` after the first time. + assert_eq!(stream.size_hint(), (0, Some(0))); + assert_eq!(stream.next().await, None); + assert_eq!(stream.size_hint(), (0, Some(0))); +} diff --git a/tests/stream_iter.rs b/tests/stream_iter.rs new file mode 100644 index 0000000..8b9ee3c --- /dev/null +++ b/tests/stream_iter.rs @@ -0,0 +1,18 @@ +use tokio_stream as stream; +use tokio_test::task; + +use std::iter; + +#[tokio::test] +async fn coop() { + let mut stream = task::spawn(stream::iter(iter::repeat(1))); + + for _ in 0..10_000 { + if stream.poll_next().is_pending() { + assert!(stream.is_woken()); + return; + } + } + + panic!("did not yield"); +} diff --git a/tests/stream_merge.rs b/tests/stream_merge.rs new file mode 100644 index 0000000..69cd568 --- /dev/null +++ b/tests/stream_merge.rs @@ -0,0 +1,83 @@ +use tokio_stream::{self as stream, Stream, StreamExt}; +use tokio_test::task; +use tokio_test::{assert_pending, assert_ready}; + +mod support { + pub(crate) mod mpsc; +} + +use support::mpsc; + +#[tokio::test] +async fn merge_sync_streams() { + let mut s = stream::iter(vec![0, 2, 4, 6]).merge(stream::iter(vec![1, 3, 5])); + + for i in 0..7 { + let rem = 7 - i; + assert_eq!(s.size_hint(), (rem, Some(rem))); + assert_eq!(Some(i), s.next().await); + } + + assert!(s.next().await.is_none()); +} + +#[tokio::test] +async fn merge_async_streams() { + let (tx1, rx1) = mpsc::unbounded_channel_stream(); + let (tx2, rx2) = mpsc::unbounded_channel_stream(); + + let mut rx = task::spawn(rx1.merge(rx2)); + + assert_eq!(rx.size_hint(), (0, None)); + + assert_pending!(rx.poll_next()); + + tx1.send(1).unwrap(); + + assert!(rx.is_woken()); + assert_eq!(Some(1), assert_ready!(rx.poll_next())); + + assert_pending!(rx.poll_next()); + tx2.send(2).unwrap(); + + assert!(rx.is_woken()); + assert_eq!(Some(2), assert_ready!(rx.poll_next())); + assert_pending!(rx.poll_next()); + + drop(tx1); + assert!(rx.is_woken()); + assert_pending!(rx.poll_next()); + + tx2.send(3).unwrap(); + assert!(rx.is_woken()); + assert_eq!(Some(3), assert_ready!(rx.poll_next())); + assert_pending!(rx.poll_next()); + + drop(tx2); + assert!(rx.is_woken()); + assert_eq!(None, assert_ready!(rx.poll_next())); +} + +#[test] +fn size_overflow() { + struct Monster; + + impl tokio_stream::Stream for Monster { + type Item = (); + fn poll_next( + self: std::pin::Pin<&mut Self>, + _cx: &mut std::task::Context<'_>, + ) -> std::task::Poll<Option<()>> { + panic!() + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (usize::max_value(), Some(usize::max_value())) + } + } + + let m1 = Monster; + let m2 = Monster; + let m = m1.merge(m2); + assert_eq!(m.size_hint(), (usize::max_value(), None)); +} diff --git a/tests/stream_once.rs b/tests/stream_once.rs new file mode 100644 index 0000000..f32bad3 --- /dev/null +++ b/tests/stream_once.rs @@ -0,0 +1,12 @@ +use tokio_stream::{self as stream, Stream, StreamExt}; + +#[tokio::test] +async fn basic_usage() { + let mut one = stream::once(1); + + assert_eq!(one.size_hint(), (1, Some(1))); + assert_eq!(Some(1), one.next().await); + + assert_eq!(one.size_hint(), (0, Some(0))); + assert_eq!(None, one.next().await); +} diff --git a/tests/stream_pending.rs b/tests/stream_pending.rs new file mode 100644 index 0000000..87b5d03 --- /dev/null +++ b/tests/stream_pending.rs @@ -0,0 +1,14 @@ +use tokio_stream::{self as stream, Stream, StreamExt}; +use tokio_test::{assert_pending, task}; + +#[tokio::test] +async fn basic_usage() { + let mut stream = stream::pending::<i32>(); + + for _ in 0..2 { + assert_eq!(stream.size_hint(), (0, None)); + + let mut next = task::spawn(async { stream.next().await }); + assert_pending!(next.poll()); + } +} diff --git a/tests/stream_stream_map.rs b/tests/stream_stream_map.rs new file mode 100644 index 0000000..53f3d86 --- /dev/null +++ b/tests/stream_stream_map.rs @@ -0,0 +1,386 @@ +use tokio_stream::{self as stream, pending, Stream, StreamExt, StreamMap}; +use tokio_test::{assert_ok, assert_pending, assert_ready, task}; + +mod support { + pub(crate) mod mpsc; +} + +use support::mpsc; + +use std::pin::Pin; + +macro_rules! assert_ready_some { + ($($t:tt)*) => { + match assert_ready!($($t)*) { + Some(v) => v, + None => panic!("expected `Some`, got `None`"), + } + }; +} + +macro_rules! assert_ready_none { + ($($t:tt)*) => { + match assert_ready!($($t)*) { + None => {} + Some(v) => panic!("expected `None`, got `Some({:?})`", v), + } + }; +} + +#[tokio::test] +async fn empty() { + let mut map = StreamMap::<&str, stream::Pending<()>>::new(); + + assert_eq!(map.len(), 0); + assert!(map.is_empty()); + + assert!(map.next().await.is_none()); + assert!(map.next().await.is_none()); + + assert!(map.remove("foo").is_none()); +} + +#[tokio::test] +async fn single_entry() { + let mut map = task::spawn(StreamMap::new()); + let (tx, rx) = mpsc::unbounded_channel_stream(); + let rx = Box::pin(rx); + + assert_ready_none!(map.poll_next()); + + assert!(map.insert("foo", rx).is_none()); + assert!(map.contains_key("foo")); + assert!(!map.contains_key("bar")); + + assert_eq!(map.len(), 1); + assert!(!map.is_empty()); + + assert_pending!(map.poll_next()); + + assert_ok!(tx.send(1)); + + assert!(map.is_woken()); + let (k, v) = assert_ready_some!(map.poll_next()); + assert_eq!(k, "foo"); + assert_eq!(v, 1); + + assert_pending!(map.poll_next()); + + assert_ok!(tx.send(2)); + + assert!(map.is_woken()); + let (k, v) = assert_ready_some!(map.poll_next()); + assert_eq!(k, "foo"); + assert_eq!(v, 2); + + assert_pending!(map.poll_next()); + drop(tx); + assert!(map.is_woken()); + assert_ready_none!(map.poll_next()); +} + +#[tokio::test] +async fn multiple_entries() { + let mut map = task::spawn(StreamMap::new()); + let (tx1, rx1) = mpsc::unbounded_channel_stream(); + let (tx2, rx2) = mpsc::unbounded_channel_stream(); + + let rx1 = Box::pin(rx1); + let rx2 = Box::pin(rx2); + + map.insert("foo", rx1); + map.insert("bar", rx2); + + assert_pending!(map.poll_next()); + + assert_ok!(tx1.send(1)); + + assert!(map.is_woken()); + let (k, v) = assert_ready_some!(map.poll_next()); + assert_eq!(k, "foo"); + assert_eq!(v, 1); + + assert_pending!(map.poll_next()); + + assert_ok!(tx2.send(2)); + + assert!(map.is_woken()); + let (k, v) = assert_ready_some!(map.poll_next()); + assert_eq!(k, "bar"); + assert_eq!(v, 2); + + assert_pending!(map.poll_next()); + + assert_ok!(tx1.send(3)); + assert_ok!(tx2.send(4)); + + assert!(map.is_woken()); + + // Given the randomization, there is no guarantee what order the values will + // be received in. + let mut v = (0..2) + .map(|_| assert_ready_some!(map.poll_next())) + .collect::<Vec<_>>(); + + assert_pending!(map.poll_next()); + + v.sort_unstable(); + assert_eq!(v[0].0, "bar"); + assert_eq!(v[0].1, 4); + assert_eq!(v[1].0, "foo"); + assert_eq!(v[1].1, 3); + + drop(tx1); + assert!(map.is_woken()); + assert_pending!(map.poll_next()); + drop(tx2); + + assert_ready_none!(map.poll_next()); +} + +#[tokio::test] +async fn insert_remove() { + let mut map = task::spawn(StreamMap::new()); + let (tx, rx) = mpsc::unbounded_channel_stream(); + + let rx = Box::pin(rx); + + assert_ready_none!(map.poll_next()); + + assert!(map.insert("foo", rx).is_none()); + let rx = map.remove("foo").unwrap(); + + assert_ok!(tx.send(1)); + + assert!(!map.is_woken()); + assert_ready_none!(map.poll_next()); + + assert!(map.insert("bar", rx).is_none()); + + let v = assert_ready_some!(map.poll_next()); + assert_eq!(v.0, "bar"); + assert_eq!(v.1, 1); + + assert!(map.remove("bar").is_some()); + assert_ready_none!(map.poll_next()); + + assert!(map.is_empty()); + assert_eq!(0, map.len()); +} + +#[tokio::test] +async fn replace() { + let mut map = task::spawn(StreamMap::new()); + let (tx1, rx1) = mpsc::unbounded_channel_stream(); + let (tx2, rx2) = mpsc::unbounded_channel_stream(); + + let rx1 = Box::pin(rx1); + let rx2 = Box::pin(rx2); + + assert!(map.insert("foo", rx1).is_none()); + + assert_pending!(map.poll_next()); + + let _rx1 = map.insert("foo", rx2).unwrap(); + + assert_pending!(map.poll_next()); + + tx1.send(1).unwrap(); + assert_pending!(map.poll_next()); + + tx2.send(2).unwrap(); + assert!(map.is_woken()); + let v = assert_ready_some!(map.poll_next()); + assert_eq!(v.0, "foo"); + assert_eq!(v.1, 2); +} + +#[test] +fn size_hint_with_upper() { + let mut map = StreamMap::new(); + + map.insert("a", stream::iter(vec![1])); + map.insert("b", stream::iter(vec![1, 2])); + map.insert("c", stream::iter(vec![1, 2, 3])); + + assert_eq!(3, map.len()); + assert!(!map.is_empty()); + + let size_hint = map.size_hint(); + assert_eq!(size_hint, (6, Some(6))); +} + +#[test] +fn size_hint_without_upper() { + let mut map = StreamMap::new(); + + map.insert("a", pin_box(stream::iter(vec![1]))); + map.insert("b", pin_box(stream::iter(vec![1, 2]))); + map.insert("c", pin_box(pending())); + + let size_hint = map.size_hint(); + assert_eq!(size_hint, (3, None)); +} + +#[test] +fn new_capacity_zero() { + let map = StreamMap::<&str, stream::Pending<()>>::new(); + assert_eq!(0, map.capacity()); + + assert!(map.keys().next().is_none()); +} + +#[test] +fn with_capacity() { + let map = StreamMap::<&str, stream::Pending<()>>::with_capacity(10); + assert!(10 <= map.capacity()); + + assert!(map.keys().next().is_none()); +} + +#[test] +fn iter_keys() { + let mut map = StreamMap::new(); + + map.insert("a", pending::<i32>()); + map.insert("b", pending()); + map.insert("c", pending()); + + let mut keys = map.keys().collect::<Vec<_>>(); + keys.sort_unstable(); + + assert_eq!(&keys[..], &[&"a", &"b", &"c"]); +} + +#[test] +fn iter_values() { + let mut map = StreamMap::new(); + + map.insert("a", stream::iter(vec![1])); + map.insert("b", stream::iter(vec![1, 2])); + map.insert("c", stream::iter(vec![1, 2, 3])); + + let mut size_hints = map.values().map(|s| s.size_hint().0).collect::<Vec<_>>(); + + size_hints.sort_unstable(); + + assert_eq!(&size_hints[..], &[1, 2, 3]); +} + +#[test] +fn iter_values_mut() { + let mut map = StreamMap::new(); + + map.insert("a", stream::iter(vec![1])); + map.insert("b", stream::iter(vec![1, 2])); + map.insert("c", stream::iter(vec![1, 2, 3])); + + let mut size_hints = map + .values_mut() + .map(|s: &mut _| s.size_hint().0) + .collect::<Vec<_>>(); + + size_hints.sort_unstable(); + + assert_eq!(&size_hints[..], &[1, 2, 3]); +} + +#[test] +fn clear() { + let mut map = task::spawn(StreamMap::new()); + + map.insert("a", stream::iter(vec![1])); + map.insert("b", stream::iter(vec![1, 2])); + map.insert("c", stream::iter(vec![1, 2, 3])); + + assert_ready_some!(map.poll_next()); + + map.clear(); + + assert_ready_none!(map.poll_next()); + assert!(map.is_empty()); +} + +#[test] +fn contains_key_borrow() { + let mut map = StreamMap::new(); + map.insert("foo".to_string(), pending::<()>()); + + assert!(map.contains_key("foo")); +} + +#[test] +fn one_ready_many_none() { + // Run a few times because of randomness + for _ in 0..100 { + let mut map = task::spawn(StreamMap::new()); + + map.insert(0, pin_box(stream::empty())); + map.insert(1, pin_box(stream::empty())); + map.insert(2, pin_box(stream::once("hello"))); + map.insert(3, pin_box(stream::pending())); + + let v = assert_ready_some!(map.poll_next()); + assert_eq!(v, (2, "hello")); + } +} + +proptest::proptest! { + #[test] + fn fuzz_pending_complete_mix(kinds: Vec<bool>) { + use std::task::{Context, Poll}; + + struct DidPoll<T> { + did_poll: bool, + inner: T, + } + + impl<T: Stream + Unpin> Stream for DidPoll<T> { + type Item = T::Item; + + fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) + -> Poll<Option<T::Item>> + { + self.did_poll = true; + Pin::new(&mut self.inner).poll_next(cx) + } + } + + for _ in 0..10 { + let mut map = task::spawn(StreamMap::new()); + let mut expect = 0; + + for (i, &is_empty) in kinds.iter().enumerate() { + let inner = if is_empty { + pin_box(stream::empty::<()>()) + } else { + expect += 1; + pin_box(stream::pending::<()>()) + }; + + let stream = DidPoll { + did_poll: false, + inner, + }; + + map.insert(i, stream); + } + + if expect == 0 { + assert_ready_none!(map.poll_next()); + } else { + assert_pending!(map.poll_next()); + + assert_eq!(expect, map.values().count()); + + for stream in map.values() { + assert!(stream.did_poll); + } + } + } + } +} + +fn pin_box<T: Stream<Item = U> + 'static, U>(s: T) -> Pin<Box<dyn Stream<Item = U>>> { + Box::pin(s) +} diff --git a/tests/stream_timeout.rs b/tests/stream_timeout.rs new file mode 100644 index 0000000..5697ace --- /dev/null +++ b/tests/stream_timeout.rs @@ -0,0 +1,109 @@ +#![cfg(feature = "full")] + +use tokio::time::{self, sleep, Duration}; +use tokio_stream::{self, StreamExt}; +use tokio_test::*; + +use futures::StreamExt as _; + +async fn maybe_sleep(idx: i32) -> i32 { + if idx % 2 == 0 { + sleep(ms(200)).await; + } + idx +} + +fn ms(n: u64) -> Duration { + Duration::from_millis(n) +} + +#[tokio::test] +async fn basic_usage() { + time::pause(); + + // Items 2 and 4 time out. If we run the stream until it completes, + // we end up with the following items: + // + // [Ok(1), Err(Elapsed), Ok(2), Ok(3), Err(Elapsed), Ok(4)] + + let stream = stream::iter(1..=4).then(maybe_sleep).timeout(ms(100)); + let mut stream = task::spawn(stream); + + // First item completes immediately + assert_ready_eq!(stream.poll_next(), Some(Ok(1))); + + // Second item is delayed 200ms, times out after 100ms + assert_pending!(stream.poll_next()); + + time::advance(ms(150)).await; + let v = assert_ready!(stream.poll_next()); + assert!(v.unwrap().is_err()); + + assert_pending!(stream.poll_next()); + + time::advance(ms(100)).await; + assert_ready_eq!(stream.poll_next(), Some(Ok(2))); + + // Third item is ready immediately + assert_ready_eq!(stream.poll_next(), Some(Ok(3))); + + // Fourth item is delayed 200ms, times out after 100ms + assert_pending!(stream.poll_next()); + + time::advance(ms(60)).await; + assert_pending!(stream.poll_next()); // nothing ready yet + + time::advance(ms(60)).await; + let v = assert_ready!(stream.poll_next()); + assert!(v.unwrap().is_err()); // timeout! + + time::advance(ms(120)).await; + assert_ready_eq!(stream.poll_next(), Some(Ok(4))); + + // Done. + assert_ready_eq!(stream.poll_next(), None); +} + +#[tokio::test] +async fn return_elapsed_errors_only_once() { + time::pause(); + + let stream = stream::iter(1..=3).then(maybe_sleep).timeout(ms(50)); + let mut stream = task::spawn(stream); + + // First item completes immediately + assert_ready_eq!(stream.poll_next(), Some(Ok(1))); + + // Second item is delayed 200ms, times out after 50ms. Only one `Elapsed` + // error is returned. + assert_pending!(stream.poll_next()); + // + time::advance(ms(51)).await; + let v = assert_ready!(stream.poll_next()); + assert!(v.unwrap().is_err()); // timeout! + + // deadline elapses again, but no error is returned + time::advance(ms(50)).await; + assert_pending!(stream.poll_next()); + + time::advance(ms(100)).await; + assert_ready_eq!(stream.poll_next(), Some(Ok(2))); + assert_ready_eq!(stream.poll_next(), Some(Ok(3))); + + // Done + assert_ready_eq!(stream.poll_next(), None); +} + +#[tokio::test] +async fn no_timeouts() { + let stream = stream::iter(vec![1, 3, 5]) + .then(maybe_sleep) + .timeout(ms(100)); + + let mut stream = task::spawn(stream); + + assert_ready_eq!(stream.poll_next(), Some(Ok(1))); + assert_ready_eq!(stream.poll_next(), Some(Ok(3))); + assert_ready_eq!(stream.poll_next(), Some(Ok(5))); + assert_ready_eq!(stream.poll_next(), None); +} diff --git a/tests/support/mpsc.rs b/tests/support/mpsc.rs new file mode 100644 index 0000000..09dbe04 --- /dev/null +++ b/tests/support/mpsc.rs @@ -0,0 +1,15 @@ +use async_stream::stream; +use tokio::sync::mpsc::{self, UnboundedSender}; +use tokio_stream::Stream; + +pub fn unbounded_channel_stream<T: Unpin>() -> (UnboundedSender<T>, impl Stream<Item = T>) { + let (tx, mut rx) = mpsc::unbounded_channel(); + + let stream = stream! { + while let Some(item) = rx.recv().await { + yield item; + } + }; + + (tx, stream) +} diff --git a/tests/time_throttle.rs b/tests/time_throttle.rs new file mode 100644 index 0000000..42a643b --- /dev/null +++ b/tests/time_throttle.rs @@ -0,0 +1,28 @@ +#![warn(rust_2018_idioms)] +#![cfg(feature = "full")] + +use tokio::time; +use tokio_stream::StreamExt; +use tokio_test::*; + +use std::time::Duration; + +#[tokio::test] +async fn usage() { + time::pause(); + + let mut stream = task::spawn(futures::stream::repeat(()).throttle(Duration::from_millis(100))); + + assert_ready!(stream.poll_next()); + assert_pending!(stream.poll_next()); + + time::advance(Duration::from_millis(90)).await; + + assert_pending!(stream.poll_next()); + + time::advance(Duration::from_millis(101)).await; + + assert!(stream.is_woken()); + + assert_ready!(stream.poll_next()); +} |