feat(swarm): remove handler field from ConnectionClosed event

misc/allow-block-list/src/lib.rs

@@ -231,7 +231,7 @@ where
         Ok(dummy::ConnectionHandler)
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         match event {
             FromSwarm::ConnectionClosed(_) => {}
             FromSwarm::ConnectionEstablished(_) => {}

misc/connection-limits/src/lib.rs

@@ -314,7 +314,7 @@ impl NetworkBehaviour for Behaviour {
         Ok(dummy::ConnectionHandler)
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         match event {
             FromSwarm::ConnectionClosed(ConnectionClosed {
                 peer_id,

protocols/autonat/src/behaviour.rs

@@ -362,16 +362,14 @@ impl Behaviour {
             peer_id,
             connection_id,
             endpoint,
-            handler,
             remaining_established,
-        }: ConnectionClosed<<Self as NetworkBehaviour>::ConnectionHandler>,
+        }: ConnectionClosed,
     ) {
         self.inner
             .on_swarm_event(FromSwarm::ConnectionClosed(ConnectionClosed {
                 peer_id,
                 connection_id,
                 endpoint,
-                handler,
                 remaining_established,
             }));
 
@@ -536,7 +534,7 @@ impl NetworkBehaviour for Behaviour {
             .handle_established_outbound_connection(connection_id, peer, addr, role_override)
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         self.listen_addresses.on_swarm_event(&event);
 
         match event {

protocols/dcutr/src/behaviour_impl.rs

@@ -164,7 +164,7 @@ impl Behaviour {
             connection_id,
             endpoint: connected_point,
             ..
-        }: ConnectionClosed<<Self as NetworkBehaviour>::ConnectionHandler>,
+        }: ConnectionClosed,
     ) {
         if !connected_point.is_relayed() {
             let connections = self
@@ -357,7 +357,7 @@ impl NetworkBehaviour for Behaviour {
         Poll::Pending
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         self.external_addresses.on_swarm_event(&event);
 
         match event {

protocols/floodsub/src/layer.rs

@@ -307,7 +307,7 @@ impl Floodsub {
             peer_id,
             remaining_established,
             ..
-        }: ConnectionClosed<<Self as NetworkBehaviour>::ConnectionHandler>,
+        }: ConnectionClosed,
     ) {
         if remaining_established > 0 {
             // we only care about peer disconnections
@@ -478,7 +478,7 @@ impl NetworkBehaviour for Floodsub {
         Poll::Pending
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         match event {
             FromSwarm::ConnectionEstablished(connection_established) => {
                 self.on_connection_established(connection_established)

protocols/gossipsub/src/behaviour.rs

@@ -3135,7 +3135,7 @@ where
             endpoint,
             remaining_established,
             ..
-        }: ConnectionClosed<<Self as NetworkBehaviour>::ConnectionHandler>,
+        }: ConnectionClosed,
     ) {
         // Remove IP from peer scoring system
         if let Some((peer_score, ..)) = &mut self.peer_score {
@@ -3484,7 +3484,7 @@ where
         Poll::Pending
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         match event {
             FromSwarm::ConnectionEstablished(connection_established) => {
                 self.on_connection_established(connection_established)

protocols/gossipsub/src/behaviour/tests.rs

@@ -21,7 +21,6 @@
 // Collection of tests for the gossipsub network behaviour
 
 use super::*;
-use crate::protocol::ProtocolConfig;
 use crate::subscription_filter::WhitelistSubscriptionFilter;
 use crate::transform::{DataTransform, IdentityTransform};
 use crate::types::FastMessageId;
@@ -272,13 +271,10 @@ where
         for connection_id in peer_connections.connections.clone() {
             active_connections = active_connections.checked_sub(1).unwrap();
 
-            let dummy_handler = Handler::new(ProtocolConfig::default(), Duration::ZERO);
-
             gs.on_swarm_event(FromSwarm::ConnectionClosed(ConnectionClosed {
                 peer_id: *peer_id,
                 connection_id,
                 endpoint: &fake_endpoint,
-                handler: dummy_handler,
                 remaining_established: active_connections,
             }));
         }

protocols/identify/src/behaviour.rs

@@ -339,7 +339,7 @@ impl NetworkBehaviour for Behaviour {
         Ok(self.discovered_peers.get(&peer))
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         let listen_addr_changed = self.listen_addresses.on_swarm_event(&event);
         let external_addr_changed = self.external_addresses.on_swarm_event(&event);
 

protocols/kad/src/behaviour.rs

@@ -1941,7 +1941,7 @@ where
             remaining_established,
             connection_id,
             ..
-        }: ConnectionClosed<<Self as NetworkBehaviour>::ConnectionHandler>,
+        }: ConnectionClosed,
     ) {
         self.connections.remove(&connection_id);
 
@@ -2433,7 +2433,7 @@ where
         }
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         self.listen_addresses.on_swarm_event(&event);
         let external_addresses_changed = self.external_addresses.on_swarm_event(&event);
 

protocols/mdns/src/behaviour.rs

@@ -224,7 +224,7 @@ where
         void::unreachable(ev)
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         self.listen_addresses.on_swarm_event(&event);
 
         match event {

protocols/perf/src/client.rs

@@ -155,7 +155,7 @@ impl NetworkBehaviour for Behaviour {
         )
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         match event {
             FromSwarm::ConnectionEstablished(ConnectionEstablished { peer_id, .. }) => {
                 self.connected.insert(peer_id);
@@ -164,7 +164,6 @@ impl NetworkBehaviour for Behaviour {
                 peer_id,
                 connection_id: _,
                 endpoint: _,
-                handler: _,
                 remaining_established,
             }) => {
                 if remaining_established == 0 {

protocols/perf/src/client/behaviour.rs

@@ -104,7 +104,7 @@ impl NetworkBehaviour for Behaviour {
         Ok(Handler::default())
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         match event {
             FromSwarm::ConnectionEstablished(ConnectionEstablished { peer_id, .. }) => {
                 self.connected.insert(peer_id);

protocols/perf/src/server.rs

@@ -118,7 +118,7 @@ impl NetworkBehaviour for Behaviour {
         )
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         self.request_response.on_swarm_event(event);
     }
 

protocols/perf/src/server/behaviour.rs

@@ -77,7 +77,7 @@ impl NetworkBehaviour for Behaviour {
         Ok(Handler::default())
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         match event {
             FromSwarm::ConnectionEstablished(_) => {}
             FromSwarm::ConnectionClosed(_) => {}

protocols/ping/src/lib.rs

@@ -153,7 +153,7 @@ impl NetworkBehaviour for Behaviour {
         }
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         match event {
             FromSwarm::ConnectionEstablished(_)
             | FromSwarm::ConnectionClosed(_)

protocols/relay/src/behaviour.rs

@@ -219,7 +219,7 @@ impl Behaviour {
             peer_id,
             connection_id,
             ..
-        }: ConnectionClosed<<Self as NetworkBehaviour>::ConnectionHandler>,
+        }: ConnectionClosed,
     ) {
         if let hash_map::Entry::Occupied(mut peer) = self.reservations.entry(peer_id) {
             peer.get_mut().remove(&connection_id);
@@ -301,7 +301,7 @@ impl NetworkBehaviour for Behaviour {
         )))
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         self.external_addresses.on_swarm_event(&event);
 
         match event {

protocols/relay/src/priv_client.rs

@@ -125,7 +125,7 @@ impl Behaviour {
             connection_id,
             endpoint,
             ..
-        }: ConnectionClosed<<Self as NetworkBehaviour>::ConnectionHandler>,
+        }: ConnectionClosed,
     ) {
         if !endpoint.is_relayed() {
             match self.directly_connected_peers.entry(peer_id) {
@@ -193,7 +193,7 @@ impl NetworkBehaviour for Behaviour {
         Ok(Either::Left(handler))
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         match event {
             FromSwarm::ConnectionEstablished(ConnectionEstablished {
                 peer_id,

protocols/rendezvous/src/client.rs

@@ -226,7 +226,7 @@ impl NetworkBehaviour for Behaviour {
             .on_connection_handler_event(peer_id, connection_id, event);
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         self.external_addresses.on_swarm_event(&event);
 
         self.inner.on_swarm_event(event);

protocols/rendezvous/src/server.rs

@@ -231,7 +231,7 @@ impl NetworkBehaviour for Behaviour {
         }
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         self.inner.on_swarm_event(event);
     }
 }

protocols/request-response/src/lib.rs

@@ -644,7 +644,7 @@ where
             connection_id,
             remaining_established,
             ..
-        }: ConnectionClosed<<Self as NetworkBehaviour>::ConnectionHandler>,
+        }: ConnectionClosed,
     ) {
         let connections = self
             .connected
@@ -765,7 +765,7 @@ where
         ))
     }
 
-    fn on_swarm_event(&mut self, event: FromSwarm<Self::ConnectionHandler>) {
+    fn on_swarm_event(&mut self, event: FromSwarm) {
         match event {
             FromSwarm::ConnectionEstablished(connection_established) => {
                 self.on_connection_established(connection_established)

swarm-derive/src/lib.rs

@@ -286,26 +286,15 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> syn::Result<Toke
         data_struct
             .fields
             .iter()
-            .enumerate()
-            // The outmost handler belongs to the last behaviour.
             .rev()
             .enumerate()
-            .map(|(enum_n, (field_n, field))| {
-                let handler = if field_n == 0 {
-                    // Given that the iterator is reversed, this is the innermost handler only.
-                    quote! { let handler = handlers }
-                } else {
-                    quote! {
-                        let (handlers, handler) = handlers.into_inner()
-                    }
-                };
+            .map(|(enum_n, field)| {
                 let inject = match field.ident {
                     Some(ref i) => quote! {
                     self.#i.on_swarm_event(#from_swarm::ConnectionClosed(#connection_closed {
                             peer_id,
                             connection_id,
                             endpoint,
-                            handler,
                             remaining_established,
                         }));
                     },
@@ -314,14 +303,12 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> syn::Result<Toke
                             peer_id,
                             connection_id,
                             endpoint,
-                            handler,
                             remaining_established,
                         }));
                     },
                 };
 
                 quote! {
-                    #handler;
                     #inject;
                 }
             })
@@ -842,7 +829,7 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> syn::Result<Toke
                 std::task::Poll::Pending
             }
 
-            fn on_swarm_event(&mut self, event: #from_swarm<Self::ConnectionHandler>) {
+            fn on_swarm_event(&mut self, event: #from_swarm) {
                 match event {
                     #from_swarm::ConnectionEstablished(
                         #connection_established { peer_id, connection_id, endpoint, failed_addresses, other_established })
@@ -851,7 +838,7 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> syn::Result<Toke
                         #address_change { peer_id, connection_id, old, new })
                     => { #(#on_address_change_stmts)* }
                     #from_swarm::ConnectionClosed(
-                        #connection_closed { peer_id, connection_id, endpoint, handler: handlers, remaining_established })
+                        #connection_closed { peer_id, connection_id, endpoint, remaining_established })
                     => { #(#on_connection_closed_stmts)* }
                     #from_swarm::DialFailure(
                         #dial_failure { peer_id, connection_id, error })

swarm/CHANGELOG.md

@@ -66,6 +66,10 @@
 
 - Add ability to `downcast_ref` ConnectionDenied errors. See [PR 4020].
 
+- Remove `handler` field from `ConnectionClosed`.
+  If you need to transfer state from a `ConnectionHandler` to its `NetworkBehaviour` when a connection closes, use `ConnectionHandler::poll_close`.
+  See [PR 4076.
+
 [PR 3292]: https://github.com/libp2p/rust-libp2p/pull/3292
 [PR 3605]: https://github.com/libp2p/rust-libp2p/pull/3605
 [PR 3651]: https://github.com/libp2p/rust-libp2p/pull/3651
@@ -84,6 +88,7 @@
 [PR 3956]: https://github.com/libp2p/rust-libp2p/pull/3956
 [PR 4020]: https://github.com/libp2p/rust-libp2p/pull/4020
 [PR 4037]: https://github.com/libp2p/rust-libp2p/pull/4037
+[PR 4076]: https://github.com/libp2p/rust-libp2p/pull/4076
 
 ## 0.42.2