core/: Remove TInEvent and TOutEvent (#2183)

TInEvent and TOutEvent are implied through THandler and thus
superflucious. Both are removed in favor of a derivation through
THandler.

Author: mxinden

core/CHANGELOG.md

@@ -12,9 +12,18 @@
 
 - Add `From<&PublicKey> for PeerId` (see [PR 2145]).
 
+- Remove `TInEvent` and `TOutEvent` trait paramters on most public types.
+  `TInEvent` and `TOutEvent` are implied through `THandler` and thus
+  superflucious. Both are removed in favor of a derivation through `THandler`
+  (see [PR 2183]).
+
+- Require `ConnectionHandler::{InEvent,OutEvent,Error}` to implement `Debug`
+  (see [PR 2183]).
+
 [PR 2145]: https://github.com/libp2p/rust-libp2p/pull/2145
 [PR 2142]: https://github.com/libp2p/rust-libp2p/pull/2142
-[PR 2137]: https://github.com/libp2p/rust-libp2p/pull/2137/
+[PR 2137]: https://github.com/libp2p/rust-libp2p/pull/2137
+[PR 2183]: https://github.com/libp2p/rust-libp2p/pull/2183
 
 # 0.29.0 [2021-07-12]
 

core/src/connection.rs

@@ -19,7 +19,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 mod error;
-mod handler;
+pub(crate) mod handler;
 mod listeners;
 mod substream;
 

core/src/connection/handler.rs

@@ -19,7 +19,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 use crate::Multiaddr;
-use std::{task::Context, task::Poll};
+use std::{fmt::Debug, task::Context, task::Poll};
 use super::{Connected, SubstreamEndpoint};
 
 /// The interface of a connection handler.
@@ -30,14 +30,14 @@ pub trait ConnectionHandler {
     ///
     /// See also [`EstablishedConnection::notify_handler`](super::EstablishedConnection::notify_handler)
     /// and [`ConnectionHandler::inject_event`].
-    type InEvent;
+    type InEvent: Debug + Send + 'static;
     /// The outbound type of events that the handler emits to the `Network`
     /// through [`ConnectionHandler::poll`].
     ///
     /// See also [`NetworkEvent::ConnectionEvent`](crate::network::NetworkEvent::ConnectionEvent).
-    type OutEvent;
+    type OutEvent: Debug + Send + 'static;
     /// The type of errors that the handler can produce when polled by the `Network`.
-    type Error;
+    type Error: Debug + Send + 'static;
     /// The type of the substream containing the data.
     type Substream;
     /// Information about a substream. Can be sent to the handler through a `SubstreamEndpoint`,
@@ -91,6 +91,10 @@ where
     }
 }
 
+pub(crate) type THandlerInEvent<THandler> = <<THandler as IntoConnectionHandler>::Handler as ConnectionHandler>::InEvent;
+pub(crate) type THandlerOutEvent<THandler> = <<THandler as IntoConnectionHandler>::Handler as ConnectionHandler>::OutEvent;
+pub(crate) type THandlerError<THandler> = <<THandler as IntoConnectionHandler>::Handler as ConnectionHandler>::Error;
+
 /// Event produced by a handler.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub enum ConnectionHandlerEvent<TOutboundOpenInfo, TCustom> {
@@ -127,4 +131,3 @@ impl<TOutboundOpenInfo, TCustom> ConnectionHandlerEvent<TOutboundOpenInfo, TCust
         }
     }
 }
-

core/src/connection/manager.rs

@@ -44,7 +44,12 @@ use super::{
     ConnectionHandler,
     IntoConnectionHandler,
     PendingConnectionError,
-    Substream
+    Substream,
+    handler::{
+        THandlerInEvent,
+        THandlerOutEvent,
+        THandlerError,
+    },
 };
 use task::{Task, TaskId};
 
@@ -88,15 +93,15 @@ impl ConnectionId {
 }
 
 /// A connection `Manager` orchestrates the I/O of a set of connections.
-pub struct Manager<I, O, H, E, HE> {
+pub struct Manager<H: IntoConnectionHandler, E> {
     /// The tasks of the managed connections.
     ///
     /// Each managed connection is associated with a (background) task
     /// spawned onto an executor. Each `TaskInfo` in `tasks` is linked to such a
     /// background task via a channel. Closing that channel (i.e. dropping
     /// the sender in the associated `TaskInfo`) stops the background task,
     /// which will attempt to gracefully close the connection.
-    tasks: FnvHashMap<TaskId, TaskInfo<I>>,
+    tasks: FnvHashMap<TaskId, TaskInfo<THandlerInEvent<H>>>,
 
     /// Next available identifier for a new connection / task.
     next_task_id: TaskId,
@@ -115,13 +120,13 @@ pub struct Manager<I, O, H, E, HE> {
 
     /// Sender distributed to managed tasks for reporting events back
     /// to the manager.
-    events_tx: mpsc::Sender<task::Event<O, H, E, HE>>,
+    events_tx: mpsc::Sender<task::Event<H, E>>,
 
     /// Receiver for events reported from managed tasks.
-    events_rx: mpsc::Receiver<task::Event<O, H, E, HE>>
+    events_rx: mpsc::Receiver<task::Event<H, E>>
 }
 
-impl<I, O, H, E, HE> fmt::Debug for Manager<I, O, H, E, HE>
+impl<H: IntoConnectionHandler, E> fmt::Debug for Manager<H, E>
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_map()
@@ -179,7 +184,7 @@ enum TaskState {
 
 /// Events produced by the [`Manager`].
 #[derive(Debug)]
-pub enum Event<'a, I, O, H, TE, HE> {
+pub enum Event<'a, H: IntoConnectionHandler, TE> {
     /// A connection attempt has failed.
     PendingConnectionError {
         /// The connection ID.
@@ -206,35 +211,35 @@ pub enum Event<'a, I, O, H, TE, HE> {
         connected: Connected,
         /// The error that occurred, if any. If `None`, the connection
         /// has been actively closed.
-        error: Option<ConnectionError<HE>>,
+        error: Option<ConnectionError<THandlerError<H>>>,
     },
 
     /// A connection has been established.
     ConnectionEstablished {
         /// The entry associated with the new connection.
-        entry: EstablishedEntry<'a, I>,
+        entry: EstablishedEntry<'a, THandlerInEvent<H>>,
     },
 
     /// A connection handler has produced an event.
     ConnectionEvent {
         /// The entry associated with the connection that produced the event.
-        entry: EstablishedEntry<'a, I>,
+        entry: EstablishedEntry<'a, THandlerInEvent<H>>,
         /// The produced event.
-        event: O
+        event: THandlerOutEvent<H>
     },
 
     /// A connection to a node has changed its address.
     AddressChange {
         /// The entry associated with the connection that changed address.
-        entry: EstablishedEntry<'a, I>,
+        entry: EstablishedEntry<'a, THandlerInEvent<H>>,
         /// The former [`ConnectedPoint`].
         old_endpoint: ConnectedPoint,
         /// The new [`ConnectedPoint`].
         new_endpoint: ConnectedPoint,
     },
 }
 
-impl<I, O, H, TE, HE> Manager<I, O, H, TE, HE> {
+impl<H: IntoConnectionHandler, TE> Manager<H, TE> {
     /// Creates a new connection manager.
     pub fn new(config: ManagerConfig) -> Self {
         let (tx, rx) = mpsc::channel(config.task_event_buffer_size);
@@ -255,19 +260,13 @@ impl<I, O, H, TE, HE> Manager<I, O, H, TE, HE> {
     /// processing the node's events.
     pub fn add_pending<F, M>(&mut self, future: F, handler: H) -> ConnectionId
     where
-        I: Send + 'static,
-        O: Send + 'static,
         TE: error::Error + Send + 'static,
-        HE: error::Error + Send + 'static,
         M: StreamMuxer + Send + Sync + 'static,
         M::OutboundSubstream: Send + 'static,
         F: Future<Output = ConnectResult<M, TE>> + Send + 'static,
         H: IntoConnectionHandler + Send + 'static,
         H::Handler: ConnectionHandler<
             Substream = Substream<M>,
-            InEvent = I,
-            OutEvent = O,
-            Error = HE
         > + Send + 'static,
         <H::Handler as ConnectionHandler>::OutboundOpenInfo: Send + 'static,
     {
@@ -293,15 +292,9 @@ impl<I, O, H, TE, HE> Manager<I, O, H, TE, HE> {
         H: IntoConnectionHandler + Send + 'static,
         H::Handler: ConnectionHandler<
             Substream = Substream<M>,
-            InEvent = I,
-            OutEvent = O,
-            Error = HE
         > + Send + 'static,
         <H::Handler as ConnectionHandler>::OutboundOpenInfo: Send + 'static,
         TE: error::Error + Send + 'static,
-        HE: error::Error + Send + 'static,
-        I: Send + 'static,
-        O: Send + 'static,
         M: StreamMuxer + Send + Sync + 'static,
         M::OutboundSubstream: Send + 'static,
     {
@@ -313,7 +306,7 @@ impl<I, O, H, TE, HE> Manager<I, O, H, TE, HE> {
             sender: tx, state: TaskState::Established(info)
         });
 
-        let task: Pin<Box<Task<Pin<Box<future::Pending<_>>>, _, _, _, _, _>>> =
+        let task: Pin<Box<Task<Pin<Box<future::Pending<_>>>, _, _, _>>> =
             Box::pin(Task::established(task_id, self.events_tx.clone(), rx, conn));
 
         if let Some(executor) = &mut self.executor {
@@ -326,7 +319,7 @@ impl<I, O, H, TE, HE> Manager<I, O, H, TE, HE> {
     }
 
     /// Gets an entry for a managed connection, if it exists.
-    pub fn entry(&mut self, id: ConnectionId) -> Option<Entry<'_, I>> {
+    pub fn entry(&mut self, id: ConnectionId) -> Option<Entry<'_, THandlerInEvent<H>>> {
         if let hash_map::Entry::Occupied(task) = self.tasks.entry(id.0) {
             Some(Entry::new(task))
         } else {
@@ -340,7 +333,7 @@ impl<I, O, H, TE, HE> Manager<I, O, H, TE, HE> {
     }
 
     /// Polls the manager for events relating to the managed connections.
-    pub fn poll<'a>(&'a mut self, cx: &mut Context<'_>) -> Poll<Event<'a, I, O, H, TE, HE>> {
+    pub fn poll<'a>(&'a mut self, cx: &mut Context<'_>) -> Poll<Event<'a, H, TE>> {
         // Advance the content of `local_spawns`.
         while let Poll::Ready(Some(_)) = self.local_spawns.poll_next_unpin(cx) {}
 

core/src/connection/manager/task.rs

@@ -31,6 +31,11 @@ use crate::{
         IntoConnectionHandler,
         PendingConnectionError,
         Substream,
+        handler::{
+            THandlerInEvent,
+            THandlerOutEvent,
+            THandlerError,
+        },
     },
 };
 use futures::{prelude::*, channel::mpsc, stream};
@@ -53,23 +58,23 @@ pub enum Command<T> {
 
 /// Events that a task can emit to its manager.
 #[derive(Debug)]
-pub enum Event<T, H, TE, HE> {
+pub enum Event<H: IntoConnectionHandler, TE> {
     /// A connection to a node has succeeded.
     Established { id: TaskId, info: Connected },
     /// A pending connection failed.
     Failed { id: TaskId, error: PendingConnectionError<TE>, handler: H },
     /// A node we are connected to has changed its address.
     AddressChange { id: TaskId, new_address: Multiaddr },
     /// Notify the manager of an event from the connection.
-    Notify { id: TaskId, event: T },
+    Notify { id: TaskId, event: THandlerOutEvent<H> },
     /// A connection closed, possibly due to an error.
     ///
     /// If `error` is `None`, the connection has completed
     /// an active orderly close.
-    Closed { id: TaskId, error: Option<ConnectionError<HE>> }
+    Closed { id: TaskId, error: Option<ConnectionError<THandlerError<H>>> }
 }
 
-impl<T, H, TE, HE> Event<T, H, TE, HE> {
+impl<H: IntoConnectionHandler, TE> Event<H, TE> {
     pub fn id(&self) -> &TaskId {
         match self {
             Event::Established { id, .. } => id,
@@ -82,7 +87,7 @@ impl<T, H, TE, HE> Event<T, H, TE, HE> {
 }
 
 /// A `Task` is a [`Future`] that handles a single connection.
-pub struct Task<F, M, H, I, O, E>
+pub struct Task<F, M, H, E>
 where
     M: StreamMuxer,
     H: IntoConnectionHandler,
@@ -92,16 +97,16 @@ where
     id: TaskId,
 
     /// Sender to emit events to the manager of this task.
-    events: mpsc::Sender<Event<O, H, E, <H::Handler as ConnectionHandler>::Error>>,
+    events: mpsc::Sender<Event<H, E>>,
 
     /// Receiver for commands sent by the manager of this task.
-    commands: stream::Fuse<mpsc::Receiver<Command<I>>>,
+    commands: stream::Fuse<mpsc::Receiver<Command<THandlerInEvent<H>>>>,
 
     /// Inner state of this `Task`.
-    state: State<F, M, H, O, E>,
+    state: State<F, M, H, E>,
 }
 
-impl<F, M, H, I, O, E> Task<F, M, H, I, O, E>
+impl<F, M, H, E> Task<F, M, H, E>
 where
     M: StreamMuxer,
     H: IntoConnectionHandler,
@@ -110,8 +115,8 @@ where
     /// Create a new task to connect and handle some node.
     pub fn pending(
         id: TaskId,
-        events: mpsc::Sender<Event<O, H, E, <H::Handler as ConnectionHandler>::Error>>,
-        commands: mpsc::Receiver<Command<I>>,
+        events: mpsc::Sender<Event<H, E>>,
+        commands: mpsc::Receiver<Command<THandlerInEvent<H>>>,
         future: F,
         handler: H
     ) -> Self {
@@ -129,8 +134,8 @@ where
     /// Create a task for an existing node we are already connected to.
     pub fn established(
         id: TaskId,
-        events: mpsc::Sender<Event<O, H, E, <H::Handler as ConnectionHandler>::Error>>,
-        commands: mpsc::Receiver<Command<I>>,
+        events: mpsc::Sender<Event<H, E>>,
+        commands: mpsc::Receiver<Command<THandlerInEvent<H>>>,
         connection: Connection<M, H::Handler>
     ) -> Self {
         Task {
@@ -143,7 +148,7 @@ where
 }
 
 /// The state associated with the `Task` of a connection.
-enum State<F, M, H, O, E>
+enum State<F, M, H, E>
 where
     M: StreamMuxer,
     H: IntoConnectionHandler,
@@ -165,33 +170,35 @@ where
         /// is polled for new events in this state, otherwise the event
         /// must be sent to the `Manager` before the connection can be
         /// polled again.
-        event: Option<Event<O, H, E, <H::Handler as ConnectionHandler>::Error>>
+        event: Option<Event<H, E>>,
     },
 
     /// The connection is closing (active close).
     Closing(Close<M>),
 
     /// The task is terminating with a final event for the `Manager`.
-    Terminating(Event<O, H, E, <H::Handler as ConnectionHandler>::Error>),
+    Terminating(Event<H, E>),
 
     /// The task has finished.
     Done
 }
 
-impl<F, M, H, I, O, E> Unpin for Task<F, M, H, I, O, E>
+impl<F, M, H, E> Unpin for Task<F, M, H, E>
 where
     M: StreamMuxer,
     H: IntoConnectionHandler,
     H::Handler: ConnectionHandler<Substream = Substream<M>>
 {
 }
 
-impl<F, M, H, I, O, E> Future for Task<F, M, H, I, O, E>
+impl<F, M, H, E> Future for Task<F, M, H, E>
 where
     M: StreamMuxer,
     F: Future<Output = ConnectResult<M, E>>,
     H: IntoConnectionHandler,
-    H::Handler: ConnectionHandler<Substream = Substream<M>, InEvent = I, OutEvent = O>
+    H::Handler: ConnectionHandler<
+        Substream = Substream<M>,
+    > + Send + 'static,
 {
     type Output = ();