{core,swarm}: Remove Network abstraction (#2492)

This commit removes the `Network` abstraction, thus managing `Listeners`
and the connection `Pool` in `Swarm` directly. This is done under the
assumption that noone uses the `Network` abstraction directly, but
instead everyone always uses it through `Swarm`. Both `Listeners` and
`Pool` are moved from `libp2p-core` into `libp2p-swarm`. Given that they
are no longer exposed via `Network`, they can be treated as an
implementation detail of `libp2p-swarm` and `Swarm`.

This change does not include any behavioural changes.

This change has the followin benefits:

- Removal of `NetworkEvent`, which was mostly an isomorphism of
  `SwarmEvent`.
- Removal of the never-directly-used `Network` abstraction.
- Removal of now obsolete verbose `Peer` (`core/src/network/peer.rs`)
  construct.
- Removal of `libp2p-core` `DialOpts`, which is a direct mapping of
  `libp2p-swarm` `DialOpts`.
- Allowing breaking changes to the connection handling and `Swarm` API
  interface without a breaking change in `libp2p-core` and thus a
  without a breaking change in `/transport` protocols.

This change enables the following potential future changes:

- Removal of `NodeHandler` and `ConnectionHandler`. Thus allowing to
  rename `ProtocolsHandler` into `ConnectionHandler`.
- Moving `NetworkBehaviour` and `ProtocolsHandler` into `libp2p-core`,
  having `libp2p-xxx` protocol crates only depend on `libp2p-core` and
  thus allowing general breaking changes to `Swarm` without breaking all
  `libp2p-xxx` crates.

core/CHANGELOG.md

@@ -1,5 +1,9 @@
 # 0.32.0 [unreleased]
 
+- Remove `Network`. `libp2p-core` is from now on an auxiliary crate only. Users
+  that have previously used `Network` only, will need to use `Swarm` instead. See
+  [PR 2492].
+
 - Update to `multiaddr` `v0.14.0`.
 
 - Update to `multihash` `v0.16.0`.
@@ -10,6 +14,7 @@
 
 [PR 2456]: https://github.com/libp2p/rust-libp2p/pull/2456
 [RUSTSEC-2022-0009]: https://rustsec.org/advisories/RUSTSEC-2022-0009.html
+[PR 2492]: https://github.com/libp2p/rust-libp2p/pull/2492
 
 # 0.31.0 [2022-01-27]
 

core/Cargo.toml

@@ -49,11 +49,11 @@ criterion = "0.3"
 libp2p-mplex = { path = "../muxers/mplex" }
 libp2p-noise = { path = "../transports/noise" }
 libp2p-tcp = { path = "../transports/tcp" }
-serde_json = "1.0"
-rmp-serde = "1.0"
 multihash = { version = "0.16", default-features = false, features = ["arb"] }
 quickcheck = "0.9.0"
 rand07 = { package = "rand", version = "0.7" }
+rmp-serde = "1.0"
+serde_json = "1.0"
 
 [build-dependencies]
 prost-build = "0.9"

core/src/connection.rs

@@ -18,29 +18,7 @@
 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
-mod error;
-pub(crate) mod handler;
-mod listeners;
-mod substream;
-
-pub(crate) mod pool;
-
-pub use error::{
-    ConnectionError, PendingConnectionError, PendingInboundConnectionError,
-    PendingOutboundConnectionError,
-};
-pub use handler::{ConnectionHandler, ConnectionHandlerEvent, IntoConnectionHandler};
-pub use listeners::{ListenerId, ListenersEvent, ListenersStream};
-pub use pool::{ConnectionCounters, ConnectionLimits};
-pub use pool::{EstablishedConnection, EstablishedConnectionIter, PendingConnection};
-pub use substream::{Close, Substream, SubstreamEndpoint};
-
 use crate::multiaddr::{Multiaddr, Protocol};
-use crate::muxing::StreamMuxer;
-use crate::PeerId;
-use std::hash::Hash;
-use std::{error::Error, fmt, pin::Pin, task::Context, task::Poll};
-use substream::{Muxing, SubstreamEvent};
 
 /// Connection identifier.
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
@@ -53,7 +31,34 @@ impl ConnectionId {
     /// in test environments. There is in general no guarantee
     /// that all connection IDs are based on non-negative integers.
     pub fn new(id: usize) -> Self {
-        ConnectionId(id)
+        Self(id)
+    }
+}
+
+impl std::ops::Add<usize> for ConnectionId {
+    type Output = Self;
+
+    fn add(self, other: usize) -> Self {
+        Self(self.0 + other)
+    }
+}
+
+/// The ID of a single listener.
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct ListenerId(u64);
+
+impl ListenerId {
+    /// Creates a `ListenerId` from a non-negative integer.
+    pub fn new(id: u64) -> Self {
+        Self(id)
+    }
+}
+
+impl std::ops::Add<u64> for ListenerId {
+    type Output = Self;
+
+    fn add(self, other: u64) -> Self {
+        Self(self.0 + other)
     }
 }
 
@@ -236,181 +241,3 @@ impl ConnectedPoint {
         }
     }
 }
-
-/// Information about a successfully established connection.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Connected {
-    /// The connected endpoint, including network address information.
-    pub endpoint: ConnectedPoint,
-    /// Information obtained from the transport.
-    pub peer_id: PeerId,
-}
-
-/// Event generated by a [`Connection`].
-#[derive(Debug, Clone)]
-pub enum Event<T> {
-    /// Event generated by the [`ConnectionHandler`].
-    Handler(T),
-    /// Address of the remote has changed.
-    AddressChange(Multiaddr),
-}
-
-/// A multiplexed connection to a peer with an associated `ConnectionHandler`.
-pub struct Connection<TMuxer, THandler>
-where
-    TMuxer: StreamMuxer,
-    THandler: ConnectionHandler<Substream = Substream<TMuxer>>,
-{
-    /// Node that handles the muxing.
-    muxing: substream::Muxing<TMuxer, THandler::OutboundOpenInfo>,
-    /// Handler that processes substreams.
-    handler: THandler,
-}
-
-impl<TMuxer, THandler> fmt::Debug for Connection<TMuxer, THandler>
-where
-    TMuxer: StreamMuxer,
-    THandler: ConnectionHandler<Substream = Substream<TMuxer>> + fmt::Debug,
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("Connection")
-            .field("muxing", &self.muxing)
-            .field("handler", &self.handler)
-            .finish()
-    }
-}
-
-impl<TMuxer, THandler> Unpin for Connection<TMuxer, THandler>
-where
-    TMuxer: StreamMuxer,
-    THandler: ConnectionHandler<Substream = Substream<TMuxer>>,
-{
-}
-
-impl<TMuxer, THandler> Connection<TMuxer, THandler>
-where
-    TMuxer: StreamMuxer,
-    THandler: ConnectionHandler<Substream = Substream<TMuxer>>,
-{
-    /// Builds a new `Connection` from the given substream multiplexer
-    /// and connection handler.
-    pub fn new(muxer: TMuxer, handler: THandler) -> Self {
-        Connection {
-            muxing: Muxing::new(muxer),
-            handler,
-        }
-    }
-
-    /// Returns a reference to the `ConnectionHandler`
-    pub fn handler(&self) -> &THandler {
-        &self.handler
-    }
-
-    /// Returns a mutable reference to the `ConnectionHandler`
-    pub fn handler_mut(&mut self) -> &mut THandler {
-        &mut self.handler
-    }
-
-    /// Notifies the connection handler of an event.
-    pub fn inject_event(&mut self, event: THandler::InEvent) {
-        self.handler.inject_event(event);
-    }
-
-    /// Begins an orderly shutdown of the connection, returning the connection
-    /// handler and a `Future` that resolves when connection shutdown is complete.
-    pub fn close(self) -> (THandler, Close<TMuxer>) {
-        (self.handler, self.muxing.close().0)
-    }
-
-    /// Polls the connection for events produced by the associated handler
-    /// as a result of I/O activity on the substream multiplexer.
-    pub fn poll(
-        mut self: Pin<&mut Self>,
-        cx: &mut Context<'_>,
-    ) -> Poll<Result<Event<THandler::OutEvent>, ConnectionError<THandler::Error>>> {
-        loop {
-            let mut io_pending = false;
-
-            // Perform I/O on the connection through the muxer, informing the handler
-            // of new substreams.
-            match self.muxing.poll(cx) {
-                Poll::Pending => io_pending = true,
-                Poll::Ready(Ok(SubstreamEvent::InboundSubstream { substream })) => self
-                    .handler
-                    .inject_substream(substream, SubstreamEndpoint::Listener),
-                Poll::Ready(Ok(SubstreamEvent::OutboundSubstream {
-                    user_data,
-                    substream,
-                })) => {
-                    let endpoint = SubstreamEndpoint::Dialer(user_data);
-                    self.handler.inject_substream(substream, endpoint)
-                }
-                Poll::Ready(Ok(SubstreamEvent::AddressChange(address))) => {
-                    self.handler.inject_address_change(&address);
-                    return Poll::Ready(Ok(Event::AddressChange(address)));
-                }
-                Poll::Ready(Err(err)) => return Poll::Ready(Err(ConnectionError::IO(err))),
-            }
-
-            // Poll the handler for new events.
-            match self.handler.poll(cx) {
-                Poll::Pending => {
-                    if io_pending {
-                        return Poll::Pending; // Nothing to do
-                    }
-                }
-                Poll::Ready(Ok(ConnectionHandlerEvent::OutboundSubstreamRequest(user_data))) => {
-                    self.muxing.open_substream(user_data);
-                }
-                Poll::Ready(Ok(ConnectionHandlerEvent::Custom(event))) => {
-                    return Poll::Ready(Ok(Event::Handler(event)));
-                }
-                Poll::Ready(Err(err)) => return Poll::Ready(Err(ConnectionError::Handler(err))),
-            }
-        }
-    }
-}
-
-/// Borrowed information about an incoming connection currently being negotiated.
-#[derive(Debug, Copy, Clone)]
-pub struct IncomingInfo<'a> {
-    /// Local connection address.
-    pub local_addr: &'a Multiaddr,
-    /// Address used to send back data to the remote.
-    pub send_back_addr: &'a Multiaddr,
-}
-
-impl<'a> IncomingInfo<'a> {
-    /// Builds the [`PendingPoint`] corresponding to the incoming connection.
-    pub fn to_pending_point(&self) -> PendingPoint {
-        PendingPoint::Listener {
-            local_addr: self.local_addr.clone(),
-            send_back_addr: self.send_back_addr.clone(),
-        }
-    }
-    /// Builds the [`ConnectedPoint`] corresponding to the incoming connection.
-    pub fn to_connected_point(&self) -> ConnectedPoint {
-        ConnectedPoint::Listener {
-            local_addr: self.local_addr.clone(),
-            send_back_addr: self.send_back_addr.clone(),
-        }
-    }
-}
-
-/// Information about a connection limit.
-#[derive(Debug, Clone)]
-pub struct ConnectionLimit {
-    /// The maximum number of connections.
-    pub limit: u32,
-    /// The current number of connections.
-    pub current: u32,
-}
-
-impl fmt::Display for ConnectionLimit {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}/{}", self.current, self.limit)
-    }
-}
-
-/// A `ConnectionLimit` can represent an error if it has been exceeded.
-impl Error for ConnectionLimit {}

core/src/lib.rs

@@ -61,18 +61,16 @@ pub mod connection;
 pub mod either;
 pub mod identity;
 pub mod muxing;
-pub mod network;
 pub mod peer_record;
 pub mod signed_envelope;
 pub mod transport;
 pub mod upgrade;
 
-pub use connection::{Connected, ConnectedPoint, Endpoint};
+pub use connection::{ConnectedPoint, Endpoint};
 pub use identity::PublicKey;
 pub use multiaddr::Multiaddr;
 pub use multihash;
 pub use muxing::StreamMuxer;
-pub use network::{DialOpts, Network};
 pub use peer_id::PeerId;
 pub use peer_record::PeerRecord;
 pub use signed_envelope::SignedEnvelope;