Move stream items into tokio-stream

This change removes all references to `Stream` from
within the `tokio` crate and moves them into a new
`tokio-stream` crate. Most types have had their
`impl Stream` removed as well in-favor of their
inherent methods.

Closes #2870

CONTRIBUTING.md

@@ -486,7 +486,6 @@ missing a difficulty rating, and you should feel free to add one.
  - **M-process** The `tokio::process` module.
  - **M-runtime** The `tokio::runtime` module.
  - **M-signal** The `tokio::signal` module.
- - **M-stream** The `tokio::stream` module.
  - **M-sync** The `tokio::sync` module.
  - **M-task** The `tokio::task` module.
  - **M-time** The `tokio::time` module.

Cargo.toml

@@ -4,6 +4,7 @@ members = [
   "tokio",
   "tokio-macros",
   "tokio-test",
+  "tokio-stream",
   "tokio-util",
 
   # Internal

examples/Cargo.toml

@@ -8,9 +8,12 @@ edition = "2018"
 # [dependencies] instead.
 [dev-dependencies]
 tokio = { version = "1.0.0", path = "../tokio", features = ["full", "tracing"] }
+tokio-util = { version = "0.6.0", path = "../tokio-util", features = ["full"] }
+tokio-stream = { version = "0.1", path = "../tokio-stream" }
+
+async-stream = "0.3"
 tracing = "0.1"
 tracing-subscriber = { version = "0.2.7", default-features = false, features = ["fmt", "ansi", "env-filter", "chrono", "tracing-log"] }
-tokio-util = { version = "0.6.0", path = "../tokio-util", features = ["full"] }
 bytes = "0.6"
 futures = "0.3.0"
 http = "0.2"

examples/chat.rs

@@ -27,8 +27,8 @@
 #![warn(rust_2018_idioms)]
 
 use tokio::net::{TcpListener, TcpStream};
-use tokio::stream::{Stream, StreamExt};
 use tokio::sync::{mpsc, Mutex};
+use tokio_stream::{Stream, StreamExt};
 use tokio_util::codec::{Framed, LinesCodec, LinesCodecError};
 
 use futures::SinkExt;
@@ -101,9 +101,6 @@ async fn main() -> Result<(), Box<dyn Error>> {
 /// Shorthand for the transmit half of the message channel.
 type Tx = mpsc::UnboundedSender<String>;
 
-/// Shorthand for the receive half of the message channel.
-type Rx = mpsc::UnboundedReceiver<String>;
-
 /// Data that is shared between all peers in the chat server.
 ///
 /// This is the set of `Tx` handles for all connected clients. Whenever a
@@ -127,7 +124,7 @@ struct Peer {
     ///
     /// This is used to receive messages from peers. When a message is received
     /// off of this `Rx`, it will be written to the socket.
-    rx: Rx,
+    rx: Pin<Box<dyn Stream<Item = String> + Send>>,
 }
 
 impl Shared {
@@ -159,11 +156,17 @@ impl Peer {
         let addr = lines.get_ref().peer_addr()?;
 
         // Create a channel for this peer
-        let (tx, rx) = mpsc::unbounded_channel();
+        let (tx, mut rx) = mpsc::unbounded_channel();
 
         // Add an entry for this `Peer` in the shared state map.
         state.lock().await.peers.insert(addr, tx);
 
+        let rx = Box::pin(async_stream::stream! {
+            while let Some(item) = rx.recv().await {
+                yield item;
+            }
+        });
+
         Ok(Peer { lines, rx })
     }
 }

examples/print_each_packet.rs

@@ -55,7 +55,7 @@
 #![warn(rust_2018_idioms)]
 
 use tokio::net::TcpListener;
-use tokio::stream::StreamExt;
+use tokio_stream::StreamExt;
 use tokio_util::codec::{BytesCodec, Decoder};
 
 use std::env;

examples/tinydb.rs

@@ -42,7 +42,7 @@
 #![warn(rust_2018_idioms)]
 
 use tokio::net::TcpListener;
-use tokio::stream::StreamExt;
+use tokio_stream::StreamExt;
 use tokio_util::codec::{Framed, LinesCodec};
 
 use futures::SinkExt;

examples/tinyhttp.rs

@@ -20,7 +20,7 @@ use http::{header::HeaderValue, Request, Response, StatusCode};
 extern crate serde_derive;
 use std::{env, error::Error, fmt, io};
 use tokio::net::{TcpListener, TcpStream};
-use tokio::stream::StreamExt;
+use tokio_stream::StreamExt;
 use tokio_util::codec::{Decoder, Encoder, Framed};
 
 #[tokio::main]

examples/udp-codec.rs

@@ -9,8 +9,8 @@
 #![warn(rust_2018_idioms)]
 
 use tokio::net::UdpSocket;
-use tokio::stream::StreamExt;
 use tokio::{io, time};
+use tokio_stream::StreamExt;
 use tokio_util::codec::BytesCodec;
 use tokio_util::udp::UdpFramed;
 

tokio-stream/Cargo.toml

@@ -0,0 +1,35 @@
+[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 = "0.1.0"
+edition = "2018"
+authors = ["Tokio Contributors <[email protected]>"]
+license = "MIT"
+repository = "https://github.com/tokio-rs/tokio"
+homepage = "https://tokio.rs"
+documentation = "https://docs.rs/tokio-stream/0.1.0/tokio_stream"
+description = """
+Utilities to work with `Stream` and `tokio`.
+"""
+categories = ["asynchronous"]
+publish = false
+
+[dependencies]
+futures-core = { version = "0.3.0" }
+pin-project-lite = "0.2.0"
+rand = "0.7.3"
+tokio = { version = "1.0", path = "../tokio", features = ["sync"] }
+async-stream = "0.3"
+
+[dev-dependencies]
+tokio = { version = "1.0", path = "../tokio", features = ["full"] }
+tokio-test = { path = "../tokio-test" }
+futures = { version = "0.3", default-features = false }
+
+proptest = "0.10.0"

tokio/src/stream/all.rs → tokio-stream/src/all.rs

@@ -1,4 +1,4 @@
-use crate::stream::Stream;
+use crate::Stream;
 
 use core::future::Future;
 use core::marker::PhantomPinned;

tokio/src/stream/any.rs → tokio-stream/src/any.rs

@@ -1,4 +1,4 @@
-use crate::stream::Stream;
+use crate::Stream;
 
 use core::future::Future;
 use core::marker::PhantomPinned;

tokio/src/stream/chain.rs → tokio-stream/src/chain.rs

@@ -1,4 +1,4 @@
-use crate::stream::{Fuse, Stream};
+use crate::{Fuse, Stream};
 
 use core::pin::Pin;
 use core::task::{Context, Poll};

tokio/src/stream/collect.rs → tokio-stream/src/collect.rs

@@ -1,4 +1,4 @@
-use crate::stream::Stream;
+use crate::Stream;
 
 use core::future::Future;
 use core::marker::PhantomPinned;

tokio/src/stream/empty.rs → tokio-stream/src/empty.rs

@@ -1,4 +1,4 @@
-use crate::stream::Stream;
+use crate::Stream;
 
 use core::marker::PhantomData;
 use core::pin::Pin;
@@ -24,7 +24,7 @@ unsafe impl<T> Sync for Empty<T> {}
 /// Basic usage:
 ///
 /// ```
-/// use tokio::stream::{self, StreamExt};
+/// use tokio_stream::{self as stream, StreamExt};
 ///
 /// #[tokio::main]
 /// async fn main() {

tokio/src/stream/filter.rs → tokio-stream/src/filter.rs

@@ -1,4 +1,4 @@
-use crate::stream::Stream;
+use crate::Stream;
 
 use core::fmt;
 use core::pin::Pin;

tokio/src/stream/filter_map.rs → tokio-stream/src/filter_map.rs

@@ -1,4 +1,4 @@
-use crate::stream::Stream;
+use crate::Stream;
 
 use core::fmt;
 use core::pin::Pin;

tokio/src/stream/fold.rs → tokio-stream/src/fold.rs

@@ -1,4 +1,4 @@
-use crate::stream::Stream;
+use crate::Stream;
 
 use core::future::Future;
 use core::marker::PhantomPinned;

tokio/src/stream/fuse.rs → tokio-stream/src/fuse.rs

@@ -1,4 +1,4 @@
-use crate::stream::Stream;
+use crate::Stream;
 
 use pin_project_lite::pin_project;
 use std::pin::Pin;

tokio/src/stream/iter.rs → tokio-stream/src/iter.rs

@@ -1,4 +1,4 @@
-use crate::stream::Stream;
+use crate::Stream;
 
 use core::pin::Pin;
 use core::task::{Context, Poll};
@@ -8,6 +8,7 @@ use core::task::{Context, Poll};
 #[must_use = "streams do nothing unless polled"]
 pub struct Iter<I> {
     iter: I,
+    yield_amt: usize,
 }
 
 impl<I> Unpin for Iter<I> {}
@@ -20,7 +21,7 @@ impl<I> Unpin for Iter<I> {}
 ///
 /// ```
 /// # async fn dox() {
-/// use tokio::stream::{self, StreamExt};
+/// use tokio_stream::{self as stream, StreamExt};
 ///
 /// let mut stream = stream::iter(vec![17, 19]);
 ///
@@ -35,6 +36,7 @@ where
 {
     Iter {
         iter: i.into_iter(),
+        yield_amt: 0,
     }
 }
 
@@ -45,9 +47,18 @@ where
     type Item = I::Item;
 
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<I::Item>> {
-        let coop = ready!(crate::coop::poll_proceed(cx));
-        coop.made_progress();
-        Poll::Ready(self.iter.next())
+        // 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>) {