swarm: Remove NotifyHandler::All (#1880)

Remove `NotifyHandler::All` thus removing the requirement for events
send from a `NetworkBehaviour` to a `ProtocolsHandler` to be `Clone`. An
implementor of `NetworkBehaviour` can still notify all
`ProtocolHandler`s for a given peer by emitting one `NotifyHandler`
event per connection to that peer.

protocols/kad/src/handler.rs

@@ -329,7 +329,7 @@ impl From<ProtocolsHandlerUpgrErr<io::Error>> for KademliaHandlerQueryErr {
 }
 
 /// Event to send to the handler.
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub enum KademliaHandlerIn<TUserData> {
     /// Resets the (sub)stream associated with the given request ID,
     /// thus signaling an error to the remote.
@@ -429,7 +429,7 @@ pub enum KademliaHandlerIn<TUserData> {
 
 /// Unique identifier for a request. Must be passed back in order to answer a request from
 /// the remote.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq)]
 pub struct KademliaRequestId {
     /// Unique identifier for an incoming connection.
     connec_unique_id: UniqueConnecId,

protocols/request-response/src/handler/protocol.rs

@@ -118,7 +118,7 @@ where
 /// Request substream upgrade protocol.
 ///
 /// Sends a request and receives a response.
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub struct RequestProtocol<TCodec>
 where
     TCodec: RequestResponseCodec

swarm/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 - Update `libp2p-core`.
 
+- Remove `NotifyHandler::All` thus removing the requirement for events send from
+  a `NetworkBehaviour` to a `ProtocolsHandler` to be `Clone`.
+  [PR 1880](https://github.com/libp2p/rust-libp2p/pull/1880).
+
 # 0.25.1 [2020-11-26]
 
 - Add `ExpandedSwarm::is_connected`.

swarm/src/behaviour.rs

@@ -218,7 +218,7 @@ pub trait NetworkBehaviourEventProcess<TEvent> {
 /// in whose context it is executing.
 ///
 /// [`Swarm`]: super::Swarm
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub enum NetworkBehaviourAction<TInEvent, TOutEvent> {
     /// Instructs the `Swarm` to return an event when it is being polled.
     GenerateEvent(TOutEvent),
@@ -264,7 +264,7 @@ pub enum NetworkBehaviourAction<TInEvent, TOutEvent> {
     NotifyHandler {
         /// The peer for whom a `ProtocolsHandler` should be notified.
         peer_id: PeerId,
-        /// The ID of the connection whose `ProtocolsHandler` to notify.
+        /// The options w.r.t. which connection handler to notify of the event.
         handler: NotifyHandler,
         /// The event to send.
         event: TInEvent,
@@ -325,15 +325,13 @@ impl<TInEvent, TOutEvent> NetworkBehaviourAction<TInEvent, TOutEvent> {
     }
 }
 
-/// The options w.r.t. which connection handlers to notify of an event.
+/// The options w.r.t. which connection handler to notify of an event.
 #[derive(Debug, Clone)]
 pub enum NotifyHandler {
     /// Notify a particular connection handler.
     One(ConnectionId),
     /// Notify an arbitrary connection handler.
     Any,
-    /// Notify all connection handlers.
-    All
 }
 
 /// The available conditions under which a new dialing attempt to

swarm/src/lib.rs

@@ -324,7 +324,7 @@ where
 impl<TBehaviour, TInEvent, TOutEvent, THandler, THandleErr>
     ExpandedSwarm<TBehaviour, TInEvent, TOutEvent, THandler>
 where TBehaviour: NetworkBehaviour<ProtocolsHandler = THandler>,
-      TInEvent: Clone + Send + 'static,
+      TInEvent: Send + 'static,
       TOutEvent: Send + 'static,
       THandler: IntoProtocolsHandler + Send + 'static,
       THandler::Handler: ProtocolsHandler<InEvent = TInEvent, OutEvent = TOutEvent, Error = THandleErr>,
@@ -661,13 +661,6 @@ where TBehaviour: NetworkBehaviour<ProtocolsHandler = THandler>,
                                 return Poll::Pending
                             }
                         }
-                        PendingNotifyHandler::All(ids) => {
-                            if let Some((event, ids)) = notify_all(ids, &mut peer, event, cx) {
-                                let handler = PendingNotifyHandler::All(ids);
-                                this.pending_event = Some((peer_id, handler, event));
-                                return Poll::Pending
-                            }
-                        }
                     }
                 }
             }
@@ -747,14 +740,6 @@ where TBehaviour: NetworkBehaviour<ProtocolsHandler = THandler>,
                                     return Poll::Pending
                                 }
                             }
-                            NotifyHandler::All => {
-                                let ids = peer.connections().into_ids().collect();
-                                if let Some((event, ids)) = notify_all(ids, &mut peer, event, cx) {
-                                    let handler = PendingNotifyHandler::All(ids);
-                                    this.pending_event = Some((peer_id, handler, event));
-                                    return Poll::Pending
-                                }
-                            }
                         }
                     }
                 },
@@ -771,16 +756,15 @@ where TBehaviour: NetworkBehaviour<ProtocolsHandler = THandler>,
     }
 }
 
-/// Connections to notify of a pending event.
+/// Connection to notify of a pending event.
 ///
-/// The connection IDs to notify of an event are captured at the time
+/// The connection IDs out of which to notify one of an event are captured at
-/// the behaviour emits the event, in order not to forward the event
+/// the time the behaviour emits the event, in order not to forward the event to
-/// to new connections which the behaviour may not have been aware of
+/// a new connection which the behaviour may not have been aware of at the time
-/// at the time it issued the request for sending it.
+/// it issued the request for sending it.
 enum PendingNotifyHandler {
     One(ConnectionId),
     Any(SmallVec<[ConnectionId; 10]>),
-    All(SmallVec<[ConnectionId; 10]>),
 }
 
 /// Notify a single connection of an event.
@@ -855,60 +839,11 @@ where
         })
 }
 
-/// Notify all of the given connections of a peer of an event.
-///
-/// Returns `Some` with the given event and a new list of connections if
-/// at least one of the given connections is currently not able to receive
-/// the event, in which case the current task is scheduled to be woken up and
-/// the returned connections are those which still need to receive the event.
-///
-/// Returns `None` if all connections are either closing or the event
-/// was successfully sent to all handlers whose connections are not closing,
-/// in either case the event is consumed.
-fn notify_all<'a, TTrans, TInEvent, TOutEvent, THandler>(
-    ids: SmallVec<[ConnectionId; 10]>,
-    peer: &mut ConnectedPeer<'a, TTrans, TInEvent, TOutEvent, THandler>,
-    event: TInEvent,
-    cx: &mut Context<'_>,
-) -> Option<(TInEvent, SmallVec<[ConnectionId; 10]>)>
-where
-    TTrans: Transport,
-    TInEvent: Clone,
-    THandler: IntoConnectionHandler,
-{
-    if ids.len() == 1 {
-        if let Some(mut conn) = peer.connection(ids[0]) {
-            return notify_one(&mut conn, event, cx).map(|e| (e, ids))
-        }
-    }
-
-    let mut pending = SmallVec::new();
-    for id in ids.into_iter() {
-        if let Some(mut conn) = peer.connection(id) {
-            match conn.poll_ready_notify_handler(cx) {
-                Poll::Pending => pending.push(id),
-                Poll::Ready(Ok(())) => {
-                    // Can now only fail due to the connection suddenly closing,
-                    // which we ignore.
-                    let _ = conn.notify_handler(event.clone());
-                },
-                Poll::Ready(Err(())) => {} // connection is closing
-            }
-        }
-    }
-
-    if !pending.is_empty() {
-        return Some((event, pending))
-    }
-
-    None
-}
-
 impl<TBehaviour, TInEvent, TOutEvent, THandler> Stream for
     ExpandedSwarm<TBehaviour, TInEvent, TOutEvent, THandler>
 where TBehaviour: NetworkBehaviour<ProtocolsHandler = THandler>,
       THandler: IntoProtocolsHandler + Send + 'static,
-      TInEvent: Clone + Send + 'static,
+      TInEvent: Send + 'static,
       TOutEvent: Send + 'static,
       THandler::Handler: ProtocolsHandler<InEvent = TInEvent, OutEvent = TOutEvent>,
 {
@@ -929,7 +864,7 @@ impl<TBehaviour, TInEvent, TOutEvent, THandler> FusedStream for
     ExpandedSwarm<TBehaviour, TInEvent, TOutEvent, THandler>
 where TBehaviour: NetworkBehaviour<ProtocolsHandler = THandler>,
       THandler: IntoProtocolsHandler + Send + 'static,
-      TInEvent: Clone + Send + 'static,
+      TInEvent: Send + 'static,
       TOutEvent: Send + 'static,
       THandler::Handler: ProtocolsHandler<InEvent = TInEvent, OutEvent = TOutEvent>,
 {