feat(swarm): remove deprecated connection limits

Users are encouraged to use `libp2p::connection_limit::Behaviour` which is a one-to-one replacement for this functionality but built as a `NetworkBehaviour`.

Related: #3647.

Pull-Request: #3885.

misc/metrics/src/swarm.rs

@@ -214,10 +214,6 @@ impl<TBvEv, THandleErr> super::Recorder<libp2p_swarm::SwarmEvent<TBvEv, THandleE
                             };
                         }
                     }
-                    #[allow(deprecated)]
-                    libp2p_swarm::DialError::ConnectionLimit(_) => {
-                        record(OutgoingConnectionError::ConnectionLimit)
-                    }
                     libp2p_swarm::DialError::LocalPeerId { .. } => {
                         record(OutgoingConnectionError::LocalPeerId)
                     }
@@ -320,7 +316,6 @@ enum PeerStatus {
 
 #[derive(EncodeLabelValue, Hash, Clone, Eq, PartialEq, Debug)]
 enum OutgoingConnectionError {
-    ConnectionLimit,
     LocalPeerId,
     NoAddresses,
     DialPeerConditionFalse,
@@ -345,18 +340,13 @@ enum IncomingConnectionError {
     TransportErrorMultiaddrNotSupported,
     TransportErrorOther,
     Aborted,
-    ConnectionLimit,
     Denied,
 }
 
 impl From<&libp2p_swarm::ListenError> for IncomingConnectionError {
     fn from(error: &libp2p_swarm::ListenError) -> Self {
         match error {
             libp2p_swarm::ListenError::WrongPeerId { .. } => IncomingConnectionError::WrongPeerId,
-            #[allow(deprecated)]
-            libp2p_swarm::ListenError::ConnectionLimit(_) => {
-                IncomingConnectionError::ConnectionLimit
-            }
             libp2p_swarm::ListenError::LocalPeerId { .. } => IncomingConnectionError::LocalPeerId,
             libp2p_swarm::ListenError::Transport(
                 libp2p_core::transport::TransportError::MultiaddrNotSupported(_),

protocols/kad/src/behaviour.rs

@@ -1931,8 +1931,6 @@ where
             DialError::DialPeerConditionFalse(dial_opts::PeerCondition::Always) => {
                 unreachable!("DialPeerCondition::Always can not trigger DialPeerConditionFalse.");
             }
-            #[allow(deprecated)]
-            DialError::ConnectionLimit(_) => {}
         }
     }
 

swarm/CHANGELOG.md

@@ -30,12 +30,17 @@
 - Flatten `ConnectionHandlerUpgrErr` and rename to `StreamUpgradeError`.
   See [PR 3882].
 
+- Remove deprecated `ConnectionLimits`.
+  Users should migrate to `libp2p::connection_limits::Behaviour`.
+  See [PR 3885].
+
 [PR 3605]: https://github.com/libp2p/rust-libp2p/pull/3605
 [PR 3715]: https://github.com/libp2p/rust-libp2p/pull/3715
 [PR 3746]: https://github.com/libp2p/rust-libp2p/pull/3746
 [PR 3865]: https://github.com/libp2p/rust-libp2p/pull/3865
 [PR 3882]: https://github.com/libp2p/rust-libp2p/pull/3882
 [PR 3884]: https://github.com/libp2p/rust-libp2p/pull/3884
+[PR 3885]: https://github.com/libp2p/rust-libp2p/pull/3885
 [PR 3886]: https://github.com/libp2p/rust-libp2p/pull/3886
 
 ## 0.42.2

swarm/src/connection.rs

@@ -400,31 +400,6 @@ impl<'a> IncomingInfo<'a> {
     }
 }
 
-/// Information about a connection limit.
-#[deprecated(note = "Use `libp2p::connection_limits` instead.", since = "0.42.1")]
-#[derive(Debug, Clone, Copy)]
-pub struct ConnectionLimit {
-    /// The maximum number of connections.
-    pub limit: u32,
-    /// The current number of connections.
-    pub current: u32,
-}
-
-#[allow(deprecated)]
-impl fmt::Display for ConnectionLimit {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "connection limit exceeded ({}/{})",
-            self.current, self.limit
-        )
-    }
-}
-
-/// A `ConnectionLimit` can represent an error if it has been exceeded.
-#[allow(deprecated)]
-impl std::error::Error for ConnectionLimit {}
-
 struct SubstreamUpgrade<UserData, Upgrade> {
     user_data: Option<UserData>,
     timeout: Delay,

swarm/src/connection/error.rs

@@ -18,8 +18,6 @@
 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
-#[allow(deprecated)]
-use crate::connection::ConnectionLimit;
 use crate::transport::TransportError;
 use crate::Multiaddr;
 use crate::{ConnectedPoint, PeerId};
@@ -90,15 +88,6 @@ pub enum PendingConnectionError<TTransErr> {
     /// An error occurred while negotiating the transport protocol(s) on a connection.
     Transport(TTransErr),
 
-    /// The connection was dropped because the connection limit
-    /// for a peer has been reached.
-    #[deprecated(
-        note = "Use `libp2p::connection_limits` instead and handle `{Dial,Listen}Error::Denied::cause`.",
-        since = "0.42.1"
-    )]
-    #[allow(deprecated)]
-    ConnectionLimit(ConnectionLimit),
-
     /// Pending connection attempt has been aborted.
     Aborted,
 
@@ -117,10 +106,6 @@ impl<T> PendingConnectionError<T> {
     pub fn map<U>(self, f: impl FnOnce(T) -> U) -> PendingConnectionError<U> {
         match self {
             PendingConnectionError::Transport(t) => PendingConnectionError::Transport(f(t)),
-            #[allow(deprecated)]
-            PendingConnectionError::ConnectionLimit(l) => {
-                PendingConnectionError::ConnectionLimit(l)
-            }
             PendingConnectionError::Aborted => PendingConnectionError::Aborted,
             PendingConnectionError::WrongPeerId { obtained, endpoint } => {
                 PendingConnectionError::WrongPeerId { obtained, endpoint }
@@ -145,10 +130,6 @@ where
                     "Pending connection: Transport error on connection: {err}"
                 )
             }
-            #[allow(deprecated)]
-            PendingConnectionError::ConnectionLimit(l) => {
-                write!(f, "Connection error: Connection limit: {l}.")
-            }
             PendingConnectionError::WrongPeerId { obtained, endpoint } => {
                 write!(
                     f,
@@ -172,8 +153,6 @@ where
             PendingConnectionError::WrongPeerId { .. } => None,
             PendingConnectionError::LocalPeerId { .. } => None,
             PendingConnectionError::Aborted => None,
-            #[allow(deprecated)]
-            PendingConnectionError::ConnectionLimit(..) => None,
         }
     }
 }