stream: add next and map utility fn (#1962)

Introduces `StreamExt` trait. This trait will be used to add utility functions to make working with streams easier. This patch includes two functions: * `next`: a future returning the item in the stream. * `map`: transform each item in the stream.
tokio-rs · Dec 18, 2019 · 4c64586 · 4c64586
1 parent b0836ec
commit 4c64586
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Showing 42 changed files with 295 additions and 57 deletions.
diff --git a/examples/chat.rs b/examples/chat.rs
@@ -27,10 +27,11 @@
 #![warn(rust_2018_idioms)]
 
 use tokio::net::{TcpListener, TcpStream};
+use tokio::stream::{Stream, StreamExt};
 use tokio::sync::{mpsc, Mutex};
 use tokio_util::codec::{Framed, LinesCodec, LinesCodecError};
 
-use futures::{SinkExt, Stream, StreamExt};
+use futures::SinkExt;
 use std::collections::HashMap;
 use std::env;
 use std::error::Error;
@@ -163,12 +164,12 @@ impl Stream for Peer {
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
         // First poll the `UnboundedReceiver`.
 
-        if let Poll::Ready(Some(v)) = self.rx.poll_next_unpin(cx) {
+        if let Poll::Ready(Some(v)) = Pin::new(&mut self.rx).poll_next(cx) {
             return Poll::Ready(Some(Ok(Message::Received(v))));
         }
 
         // Secondly poll the `Framed` stream.
-        let result: Option<_> = futures::ready!(self.lines.poll_next_unpin(cx));
+        let result: Option<_> = futures::ready!(Pin::new(&mut self.lines).poll_next(cx));
 
         Poll::Ready(match result {
             // We've received a message we should broadcast to others.

diff --git a/examples/connect.rs b/examples/connect.rs
@@ -55,19 +55,21 @@ async fn main() -> Result<(), Box<dyn Error>> {
 
 mod tcp {
     use super::codec;
-    use futures::{future, Sink, SinkExt, Stream, StreamExt};
+    use futures::StreamExt;
+    use futures::{future, Sink, SinkExt};
     use std::{error::Error, io, net::SocketAddr};
     use tokio::net::TcpStream;
+    use tokio::stream::Stream;
     use tokio_util::codec::{FramedRead, FramedWrite};
 
     pub async fn connect(
         addr: &SocketAddr,
-        stdin: impl Stream<Item = Result<Vec<u8>, io::Error>> + Unpin,
+        mut stdin: impl Stream<Item = Result<Vec<u8>, io::Error>> + Unpin,
         mut stdout: impl Sink<Vec<u8>, Error = io::Error> + Unpin,
     ) -> Result<(), Box<dyn Error>> {
         let mut stream = TcpStream::connect(addr).await?;
         let (r, w) = stream.split();
-        let sink = FramedWrite::new(w, codec::Bytes);
+        let mut sink = FramedWrite::new(w, codec::Bytes);
         let mut stream = FramedRead::new(r, codec::Bytes)
             .filter_map(|i| match i {
                 Ok(i) => future::ready(Some(i)),
@@ -78,7 +80,7 @@ mod tcp {
             })
             .map(Ok);
 
-        match future::join(stdin.forward(sink), stdout.send_all(&mut stream)).await {
+        match future::join(sink.send_all(&mut stdin), stdout.send_all(&mut stream)).await {
             (Err(e), _) | (_, Err(e)) => Err(e.into()),
             _ => Ok(()),
         }
@@ -88,8 +90,9 @@ mod tcp {
 mod udp {
     use tokio::net::udp::{RecvHalf, SendHalf};
     use tokio::net::UdpSocket;
+    use tokio::stream::{Stream, StreamExt};
 
-    use futures::{future, Sink, SinkExt, Stream, StreamExt};
+    use futures::{future, Sink, SinkExt};
     use std::error::Error;
     use std::io;
     use std::net::SocketAddr;

diff --git a/examples/print_each_packet.rs b/examples/print_each_packet.rs
@@ -55,9 +55,9 @@
 #![warn(rust_2018_idioms)]
 
 use tokio::net::TcpListener;
+use tokio::stream::StreamExt;
 use tokio_util::codec::{BytesCodec, Decoder};
 
-use futures::StreamExt;
 use std::env;
 
 #[tokio::main]

diff --git a/examples/tinydb.rs b/examples/tinydb.rs
@@ -42,9 +42,10 @@
 #![warn(rust_2018_idioms)]
 
 use tokio::net::TcpListener;
+use tokio::stream::StreamExt;
 use tokio_util::codec::{Framed, LinesCodec};
 
-use futures::{SinkExt, StreamExt};
+use futures::SinkExt;
 use std::collections::HashMap;
 use std::env;
 use std::error::Error;

diff --git a/examples/tinyhttp.rs b/examples/tinyhttp.rs
@@ -14,13 +14,14 @@
 #![warn(rust_2018_idioms)]
 
 use bytes::BytesMut;
-use futures::{SinkExt, StreamExt};
+use futures::SinkExt;
 use http::{header::HeaderValue, Request, Response, StatusCode};
 #[macro_use]
 extern crate serde_derive;
 use serde_json;
 use std::{env, error::Error, fmt, io};
 use tokio::net::{TcpListener, TcpStream};
+use tokio::stream::StreamExt;
 use tokio_util::codec::{Decoder, Encoder, Framed};
 
 #[tokio::main]

diff --git a/examples/udp-codec.rs b/examples/udp-codec.rs
@@ -9,12 +9,13 @@
 #![warn(rust_2018_idioms)]
 
 use tokio::net::UdpSocket;
+use tokio::stream::StreamExt;
 use tokio::{io, time};
 use tokio_util::codec::BytesCodec;
 use tokio_util::udp::UdpFramed;
 
 use bytes::Bytes;
-use futures::{FutureExt, SinkExt, StreamExt};
+use futures::{FutureExt, SinkExt};
 use std::env;
 use std::error::Error;
 use std::net::SocketAddr;

diff --git a/tokio-test/Cargo.toml b/tokio-test/Cargo.toml
@@ -20,7 +20,7 @@ Testing utilities for Tokio- and futures-based code
 categories = ["asynchronous", "testing"]
 
 [dependencies]
-tokio = { version = "0.2.0", path = "../tokio", features = ["rt-core", "sync", "time", "test-util"] }
+tokio = { version = "0.2.0", path = "../tokio", features = ["rt-core", "stream", "sync", "time", "test-util"] }
 
 bytes = "0.5.0"
 futures-core = "0.3.0"

diff --git a/tokio-test/src/task.rs b/tokio-test/src/task.rs
@@ -2,14 +2,15 @@
 
 #![allow(clippy::mutex_atomic)]
 
-use futures_core::Stream;
 use std::future::Future;
 use std::mem;
 use std::ops;
 use std::pin::Pin;
 use std::sync::{Arc, Condvar, Mutex};
 use std::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};
 
+use tokio::stream::Stream;
+
 /// TOOD: dox
 pub fn spawn<T>(task: T) -> Spawn<T> {
     Spawn {

diff --git a/tokio-tls/tests/smoke.rs b/tokio-tls/tests/smoke.rs
@@ -3,7 +3,6 @@
 use cfg_if::cfg_if;
 use env_logger;
 use futures::join;
-use futures::stream::StreamExt;
 use native_tls;
 use native_tls::{Identity, TlsAcceptor, TlsConnector};
 use std::io::Write;
@@ -12,6 +11,7 @@ use std::process::Command;
 use std::ptr;
 use tokio::io::{AsyncReadExt, AsyncWrite, AsyncWriteExt, Error, ErrorKind};
 use tokio::net::{TcpListener, TcpStream};
+use tokio::stream::StreamExt;
 use tokio_tls;
 
 macro_rules! t {

diff --git a/tokio-util/Cargo.toml b/tokio-util/Cargo.toml
@@ -26,7 +26,7 @@ default = []
 # Shorthand for enabling everything
 full = ["codec", "udp"]
 
-codec = []
+codec = ["tokio/stream"]
 udp = ["tokio/udp"]
 
 [dependencies]

diff --git a/tokio-util/src/codec/framed.rs b/tokio-util/src/codec/framed.rs
@@ -3,10 +3,9 @@ use crate::codec::encoder::Encoder;
 use crate::codec::framed_read::{framed_read2, framed_read2_with_buffer, FramedRead2};
 use crate::codec::framed_write::{framed_write2, framed_write2_with_buffer, FramedWrite2};
 
-use tokio::io::{AsyncBufRead, AsyncRead, AsyncWrite};
+use tokio::{io::{AsyncBufRead, AsyncRead, AsyncWrite}, stream::Stream};
 
 use bytes::BytesMut;
-use futures_core::Stream;
 use futures_sink::Sink;
 use pin_project_lite::pin_project;
 use std::fmt;

diff --git a/tokio-util/src/codec/framed_read.rs b/tokio-util/src/codec/framed_read.rs
@@ -1,10 +1,9 @@
 use crate::codec::framed::{Fuse, ProjectFuse};
 use crate::codec::Decoder;
 
-use tokio::io::AsyncRead;
+use tokio::{io::AsyncRead, stream::Stream};
 
 use bytes::BytesMut;
-use futures_core::Stream;
 use futures_sink::Sink;
 use log::trace;
 use pin_project_lite::pin_project;

diff --git a/tokio-util/src/codec/framed_write.rs b/tokio-util/src/codec/framed_write.rs
@@ -2,10 +2,10 @@ use crate::codec::decoder::Decoder;
 use crate::codec::encoder::Encoder;
 use crate::codec::framed::{Fuse, ProjectFuse};
 
-use tokio::io::{AsyncBufRead, AsyncRead, AsyncWrite};
+use tokio::{io::{AsyncBufRead, AsyncRead, AsyncWrite}, stream::Stream};
 
 use bytes::BytesMut;
-use futures_core::{ready, Stream};
+use futures_core::ready;
 use futures_sink::Sink;
 use log::trace;
 use pin_project_lite::pin_project;

diff --git a/tokio-util/src/codec/mod.rs b/tokio-util/src/codec/mod.rs
@@ -6,8 +6,8 @@
 //!
 //! [`AsyncRead`]: https://docs.rs/tokio/*/tokio/io/trait.AsyncRead.html
 //! [`AsyncWrite`]: https://docs.rs/tokio/*/tokio/io/trait.AsyncWrite.html
+//! [`Stream`]: https://docs.rs/tokio/*/tokio/stream/trait.Stream.html
 //! [`Sink`]: https://docs.rs/futures-sink/*/futures_sink/trait.Sink.html
-//! [`Stream`]: https://docs.rs/futures-core/*/futures_core/stream/trait.Stream.html
 
 mod bytes_codec;
 pub use self::bytes_codec::BytesCodec;

diff --git a/tokio-util/src/udp/frame.rs b/tokio-util/src/udp/frame.rs
@@ -1,9 +1,9 @@
 use crate::codec::{Decoder, Encoder};
 
-use tokio::net::UdpSocket;
+use tokio::{net::UdpSocket, stream::Stream};
 
 use bytes::{BufMut, BytesMut};
-use futures_core::{ready, Stream};
+use futures_core::ready;
 use futures_sink::Sink;
 use std::io;
 use std::net::{Ipv4Addr, SocketAddr, SocketAddrV4};

diff --git a/tokio-util/tests/framed.rs b/tokio-util/tests/framed.rs
@@ -1,11 +1,10 @@
 #![warn(rust_2018_idioms)]
 
-use tokio::prelude::*;
+use tokio::{prelude::*, stream::StreamExt};
 use tokio_test::assert_ok;
 use tokio_util::codec::{Decoder, Encoder, Framed, FramedParts};
 
 use bytes::{Buf, BufMut, BytesMut};
-use futures::StreamExt;
 use std::io::{self, Read};
 use std::pin::Pin;
 use std::task::{Context, Poll};

diff --git a/tokio-util/tests/udp.rs b/tokio-util/tests/udp.rs
@@ -1,12 +1,11 @@
-use tokio::net::UdpSocket;
+use tokio::{net::UdpSocket, stream::StreamExt};
 use tokio_util::codec::{Decoder, Encoder};
 use tokio_util::udp::UdpFramed;
 
 use bytes::{BufMut, BytesMut};
 use futures::future::try_join;
 use futures::future::FutureExt;
 use futures::sink::SinkExt;
-use futures::stream::StreamExt;
 use std::io;
 
 #[tokio::test]

diff --git a/tokio/src/fs/read_dir.rs b/tokio/src/fs/read_dir.rs
@@ -36,7 +36,7 @@ pub async fn read_dir(path: impl AsRef<Path>) -> io::Result<ReadDir> {
 ///
 /// [`read_dir`]: read_dir
 /// [`DirEntry`]: DirEntry
-/// [`Stream`]: futures_core::Stream
+/// [`Stream`]: crate::stream::Stream
 /// [`Err`]: std::result::Result::Err
 #[derive(Debug)]
 #[must_use = "streams do nothing unless polled"]
@@ -85,7 +85,7 @@ impl ReadDir {
 }
 
 #[cfg(feature = "stream")]
-impl futures_core::Stream for ReadDir {
+impl crate::stream::Stream for ReadDir {
     type Item = io::Result<DirEntry>;
 
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {

diff --git a/tokio/src/io/util/async_buf_read_ext.rs b/tokio/src/io/util/async_buf_read_ext.rs
@@ -226,8 +226,8 @@ cfg_io_util! {
         ///
         /// ```
         /// use tokio::io::AsyncBufReadExt;
+        /// use tokio::stream::StreamExt;
         ///
-        /// use futures::{StreamExt};
         /// use std::io::Cursor;
         ///
         /// #[tokio::main]

diff --git a/tokio/src/io/util/lines.rs b/tokio/src/io/util/lines.rs
@@ -91,7 +91,7 @@ where
 }
 
 #[cfg(feature = "stream")]
-impl<R: AsyncBufRead> futures_core::Stream for Lines<R> {
+impl<R: AsyncBufRead> crate::stream::Stream for Lines<R> {
     type Item = io::Result<String>;
 
     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {

diff --git a/tokio/src/io/util/split.rs b/tokio/src/io/util/split.rs
@@ -89,7 +89,7 @@ where
 }
 
 #[cfg(feature = "stream")]
-impl<R: AsyncBufRead> futures_core::Stream for Split<R> {
+impl<R: AsyncBufRead> crate::stream::Stream for Split<R> {
     type Item = io::Result<Vec<u8>>;
 
     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {

diff --git a/tokio/src/lib.rs b/tokio/src/lib.rs
@@ -241,6 +241,10 @@ cfg_signal! {
     pub mod signal;
 }
 
+cfg_stream! {
+    pub mod stream;
+}
+
 cfg_sync! {
     pub mod sync;
 }

diff --git a/tokio/src/net/tcp/incoming.rs b/tokio/src/net/tcp/incoming.rs
@@ -28,7 +28,7 @@ impl Incoming<'_> {
 }
 
 #[cfg(feature = "stream")]
-impl futures_core::Stream for Incoming<'_> {
+impl crate::stream::Stream for Incoming<'_> {
     type Item = io::Result<TcpStream>;
 
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {

diff --git a/tokio/src/net/tcp/listener.rs b/tokio/src/net/tcp/listener.rs
@@ -250,9 +250,7 @@ impl TcpListener {
     /// # Examples
     ///
     /// ```no_run
-    /// use tokio::net::TcpListener;
-    ///
-    /// use futures::StreamExt;
+    /// use tokio::{net::TcpListener, stream::StreamExt};
     ///
     /// #[tokio::main]
     /// async fn main() {

diff --git a/tokio/src/net/unix/incoming.rs b/tokio/src/net/unix/incoming.rs
@@ -27,7 +27,7 @@ impl Incoming<'_> {
 }
 
 #[cfg(feature = "stream")]
-impl futures_core::Stream for Incoming<'_> {
+impl crate::stream::Stream for Incoming<'_> {
     type Item = io::Result<UnixStream>;
 
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {

diff --git a/tokio/src/net/unix/listener.rs b/tokio/src/net/unix/listener.rs
@@ -104,8 +104,7 @@ impl UnixListener {
     ///
     /// ```no_run
     /// use tokio::net::UnixListener;
-    ///
-    /// use futures::StreamExt;
+    /// use tokio::stream::StreamExt;
     ///
     /// #[tokio::main]
     /// async fn main() {

diff --git a/tokio/src/signal/unix.rs b/tokio/src/signal/unix.rs
@@ -482,7 +482,7 @@ impl Signal {
 }
 
 cfg_stream! {
-    impl futures_core::Stream for Signal {
+    impl crate::stream::Stream for Signal {
         type Item = ();
 
         fn poll_next(mut self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<()>> {

diff --git a/tokio/src/signal/windows.rs b/tokio/src/signal/windows.rs
@@ -209,7 +209,7 @@ impl CtrlBreak {
 }
 
 cfg_stream! {
-    impl futures_core::Stream for CtrlBreak {
+    impl crate::stream::Stream for CtrlBreak {
         type Item = ();
 
         fn poll_next(mut self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<()>> {
@@ -246,9 +246,9 @@ pub fn ctrl_break() -> io::Result<CtrlBreak> {
 mod tests {
     use super::*;
     use crate::runtime::Runtime;
-    use tokio_test::{assert_ok, assert_pending, assert_ready_ok, task};
+    use crate::stream::StreamExt;
 
-    use futures::stream::StreamExt;
+    use tokio_test::{assert_ok, assert_pending, assert_ready_ok, task};
 
     #[test]
     fn ctrl_c() {