update tokio-stream to 0.1.3 and use BroadcastStream (#2212)

## Issue Addressed

Resolves #2189 

## Proposed Changes

use tokio's `BroadcastStream`

## Additional Info

N/A


Co-authored-by: realbigsean <seananderson33@gmail.com>

Cargo.lock

@@ -6551,6 +6551,7 @@ dependencies = [
  "futures-core",
  "pin-project-lite 0.2.4",
  "tokio 1.1.0",
+ "tokio-util 0.6.3",
 ]
 
 [[package]]

beacon_node/http_api/Cargo.toml

@@ -8,7 +8,7 @@ edition = "2018"
 warp = { git = "https://github.com/paulhauner/warp ", branch = "cors-wildcard" }
 serde = { version = "1.0.116", features = ["derive"] }
 tokio = { version = "1.1.0", features = ["macros","sync"] }
-tokio-stream = "0.1.2"
+tokio-stream = { version = "0.1.3", features = ["sync"] }
 tokio-util = "0.6.3"
 parking_lot = "0.11.0"
 types = { path = "../../consensus/types" }

beacon_node/http_api/src/broadcast_stream.rs

@@ -1,66 +0,0 @@
-// TODO: this should be replaced with the tokio's `BroadcastStream` once it's added to
-// tokio-stream (https://github.com/tokio-rs/tokio/pull/3384)
-
-use std::fmt;
-use std::pin::Pin;
-use std::task::{Context, Poll};
-use tokio::sync::broadcast::error::RecvError;
-use tokio::sync::broadcast::Receiver;
-use tokio_stream::Stream;
-use tokio_util::sync::ReusableBoxFuture;
-
-/// A wrapper around [`tokio::sync::broadcast::Receiver`] that implements [`Stream`].
-///
-/// [`tokio::sync::broadcast::Receiver`]: struct@tokio::sync::broadcast::Receiver
-/// [`Stream`]: trait@crate::Stream
-pub struct BroadcastStream<T> {
-    inner: ReusableBoxFuture<(Result<T, RecvError>, Receiver<T>)>,
-}
-
-/// An error returned from the inner stream of a [`BroadcastStream`].
-#[derive(Debug, PartialEq)]
-pub enum BroadcastStreamRecvError {
-    /// The receiver lagged too far behind. Attempting to receive again will
-    /// return the oldest message still retained by the channel.
-    ///
-    /// Includes the number of skipped messages.
-    Lagged(u64),
-}
-
-async fn make_future<T: Clone>(mut rx: Receiver<T>) -> (Result<T, RecvError>, Receiver<T>) {
-    let result = rx.recv().await;
-    (result, rx)
-}
-
-impl<T: 'static + Clone + Send> BroadcastStream<T> {
-    /// Create a new `BroadcastStream`.
-    pub fn new(rx: Receiver<T>) -> Self {
-        Self {
-            inner: ReusableBoxFuture::new(make_future(rx)),
-        }
-    }
-}
-
-impl<T: 'static + Clone + Send> Stream for BroadcastStream<T> {
-    type Item = Result<T, BroadcastStreamRecvError>;
-    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
-        let (result, rx) = match self.inner.poll(cx) {
-            std::task::Poll::Ready(t) => t,
-            std::task::Poll::Pending => return std::task::Poll::Pending,
-        };
-        self.inner.set(make_future(rx));
-        match result {
-            Ok(item) => Poll::Ready(Some(Ok(item))),
-            Err(RecvError::Closed) => Poll::Ready(None),
-            Err(RecvError::Lagged(n)) => {
-                Poll::Ready(Some(Err(BroadcastStreamRecvError::Lagged(n))))
-            }
-        }
-    }
-}
-
-impl<T> fmt::Debug for BroadcastStream<T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("BroadcastStream").finish()
-    }
-}

beacon_node/http_api/src/lib.rs

@@ -7,7 +7,6 @@
 
 mod beacon_proposer_cache;
 mod block_id;
-mod broadcast_stream;
 mod metrics;
 mod state_id;
 mod validator_inclusion;
@@ -36,7 +35,7 @@ use std::future::Future;
 use std::net::{Ipv4Addr, SocketAddr, SocketAddrV4};
 use std::sync::Arc;
 use tokio::sync::mpsc::UnboundedSender;
-use tokio_stream::StreamExt;
+use tokio_stream::{wrappers::BroadcastStream, StreamExt};
 use types::{
     Attestation, AttestationDuty, AttesterSlashing, CloneConfig, CommitteeCache, Epoch, EthSpec,
     Hash256, ProposerSlashing, PublicKey, PublicKeyBytes, RelativeEpoch, SignedAggregateAndProof,
@@ -2405,23 +2404,22 @@ pub fn serve<T: BeaconChainTypes>(
                                 }
                             };
 
-                            receivers.push(broadcast_stream::BroadcastStream::new(receiver).map(
+                            receivers.push(BroadcastStream::new(receiver).map(|msg| {
-                                |msg| {
                                 match msg {
                                     Ok(data) => Event::default()
                                         .event(data.topic_name())
                                         .json_data(data)
                                         .map_err(|e| {
-                                                warp_utils::reject::server_sent_event_error(
+                                            warp_utils::reject::server_sent_event_error(format!(
-                                                    format!("{:?}", e),
+                                                "{:?}",
-                                                )
+                                                e
+                                            ))
                                         }),
                                     Err(e) => Err(warp_utils::reject::server_sent_event_error(
                                         format!("{:?}", e),
                                     )),
                                 }
-                                },
+                            }));
-                            ));
                         }
                     } else {
                         return Err(warp_utils::reject::custom_server_error(

slasher/service/Cargo.toml

@@ -15,5 +15,5 @@ slot_clock = { path = "../../common/slot_clock" }
 state_processing = { path = "../../consensus/state_processing" }
 task_executor = { path = "../../common/task_executor" }
 tokio = { version = "1.1.0", features = ["full"] }
-tokio-stream = "0.1.2"
+tokio-stream = "0.1.3"
 types = { path = "../../consensus/types" }