feat(swarm): allow both Disconnected and NotDialing condition combined

Dialing by default uses the condition `Disconnected`, but it seems appropriate to additionally prevent a dial if already dialing. This means a combination of `Disconnected` and `NotDialing`.

The default is changed to a new variant `DisconnectedAndNotDialing`. This is a breaking change.

Related: #4189.

Pull-Request: #4225.

misc/connection-limits/src/lib.rs

@@ -377,7 +377,8 @@ impl NetworkBehaviour for Behaviour {
 mod tests {
     use super::*;
     use libp2p_swarm::{
-        behaviour::toggle::Toggle, dial_opts::DialOpts, DialError, ListenError, Swarm, SwarmEvent,
+        behaviour::toggle::Toggle, dial_opts::DialOpts, dial_opts::PeerCondition, DialError,
+        ListenError, Swarm, SwarmEvent,
     };
     use libp2p_swarm_test::SwarmExt;
     use quickcheck::*;
@@ -401,14 +402,21 @@ mod tests {
             network
                 .dial(
                     DialOpts::peer_id(target)
+                        // Dial always, even if already dialing or connected.
+                        .condition(PeerCondition::Always)
                         .addresses(vec![addr.clone()])
                         .build(),
                 )
                 .expect("Unexpected connection limit.");
         }
 
         match network
-            .dial(DialOpts::peer_id(target).addresses(vec![addr]).build())
+            .dial(
+                DialOpts::peer_id(target)
+                    .condition(PeerCondition::Always)
+                    .addresses(vec![addr])
+                    .build(),
+            )
             .expect_err("Unexpected dialing success.")
         {
             DialError::Denied { cause } => {

misc/memory-connection-limits/tests/max_bytes.rs

@@ -61,6 +61,8 @@ fn max_bytes() {
         network
             .dial(
                 DialOpts::peer_id(target)
+                    // Always dial, even if connected or already dialing.
+                    .condition(libp2p_swarm::dial_opts::PeerCondition::Always)
                     .addresses(vec![addr.clone()])
                     .build(),
             )
@@ -70,7 +72,12 @@ fn max_bytes() {
     std::thread::sleep(Duration::from_millis(100)); // Memory stats are only updated every 100ms internally, ensure they are up-to-date when we try to exceed it.
 
     match network
-        .dial(DialOpts::peer_id(target).addresses(vec![addr]).build())
+        .dial(
+            DialOpts::peer_id(target)
+                .condition(libp2p_swarm::dial_opts::PeerCondition::Always)
+                .addresses(vec![addr])
+                .build(),
+        )
         .expect_err("Unexpected dialing success.")
     {
         DialError::Denied { cause } => {

misc/memory-connection-limits/tests/max_percentage.rs

@@ -27,7 +27,10 @@ use std::time::Duration;
 use sysinfo::{RefreshKind, SystemExt};
 use util::*;
 
-use libp2p_swarm::{dial_opts::DialOpts, DialError, Swarm};
+use libp2p_swarm::{
+    dial_opts::{DialOpts, PeerCondition},
+    DialError, Swarm,
+};
 use libp2p_swarm_test::SwarmExt;
 
 #[test]
@@ -63,6 +66,8 @@ fn max_percentage() {
         network
             .dial(
                 DialOpts::peer_id(target)
+                    // Always dial, even if already dialing or connected.
+                    .condition(PeerCondition::Always)
                     .addresses(vec![addr.clone()])
                     .build(),
             )
@@ -72,7 +77,12 @@ fn max_percentage() {
     std::thread::sleep(Duration::from_millis(100)); // Memory stats are only updated every 100ms internally, ensure they are up-to-date when we try to exceed it.
 
     match network
-        .dial(DialOpts::peer_id(target).addresses(vec![addr]).build())
+        .dial(
+            DialOpts::peer_id(target)
+                .condition(PeerCondition::Always)
+                .addresses(vec![addr])
+                .build(),
+        )
         .expect_err("Unexpected dialing success.")
     {
         DialError::Denied { cause } => {

protocols/kad/src/behaviour.rs

@@ -1995,7 +1995,9 @@ where
                 }
             }
             DialError::DialPeerConditionFalse(
-                dial_opts::PeerCondition::Disconnected | dial_opts::PeerCondition::NotDialing,
+                dial_opts::PeerCondition::Disconnected
+                | dial_opts::PeerCondition::NotDialing
+                | dial_opts::PeerCondition::DisconnectedAndNotDialing,
             ) => {
                 // We might (still) be connected, or about to be connected, thus do not report the
                 // failure to the queries.

swarm/CHANGELOG.md

@@ -1,5 +1,9 @@
 ## 0.44.0 - unreleased
 
+- Add `PeerCondition::DisconnectedAndNotDialing` variant, combining pre-existing conditions.
+  This is the new default.
+  A new dialing attempt is iniated _only if_ the peer is both considered disconnected and there is currently no ongoing dialing attempt.
+  See [PR 4225](https://github.com/libp2p/rust-libp2p/pull/4225).
 - Remove deprecated `keep_alive_timeout` in `OneShotHandlerConfig`.
   See [PR 4677](https://github.com/libp2p/rust-libp2p/pull/4677).
 

swarm/src/dial_opts.rs

@@ -311,14 +311,18 @@ impl WithoutPeerIdWithAddress {
 #[derive(Debug, Copy, Clone, Default)]
 pub enum PeerCondition {
     /// A new dialing attempt is initiated _only if_ the peer is currently
-    /// considered disconnected, i.e. there is no established connection
-    /// and no ongoing dialing attempt.
-    #[default]
+    /// considered disconnected, i.e. there is no established connection.
     Disconnected,
     /// A new dialing attempt is initiated _only if_ there is currently
     /// no ongoing dialing attempt, i.e. the peer is either considered
     /// disconnected or connected but without an ongoing dialing attempt.
     NotDialing,
+    /// A combination of [`Disconnected`](PeerCondition::Disconnected) and
+    /// [`NotDialing`](PeerCondition::NotDialing). A new dialing attempt is
+    /// iniated _only if_ the peer is both considered disconnected and there
+    /// is currently no ongoing dialing attempt.
+    #[default]
+    DisconnectedAndNotDialing,
     /// A new dialing attempt is always initiated, only subject to the
     /// configured connection limits.
     Always,

swarm/src/lib.rs

@@ -444,11 +444,13 @@ where
         let connection_id = dial_opts.connection_id();
 
         let should_dial = match (condition, peer_id) {
+            (_, None) => true,
             (PeerCondition::Always, _) => true,
-            (PeerCondition::Disconnected, None) => true,
-            (PeerCondition::NotDialing, None) => true,
             (PeerCondition::Disconnected, Some(peer_id)) => !self.pool.is_connected(peer_id),
             (PeerCondition::NotDialing, Some(peer_id)) => !self.pool.is_dialing(peer_id),
+            (PeerCondition::DisconnectedAndNotDialing, Some(peer_id)) => {
+                !self.pool.is_dialing(peer_id) && !self.pool.is_connected(peer_id)
+            }
         };
 
         if !should_dial {
@@ -1742,6 +1744,7 @@ impl fmt::Display for DialError {
             ),
             DialError::DialPeerConditionFalse(PeerCondition::Disconnected) => write!(f, "Dial error: dial condition was configured to only happen when disconnected (`PeerCondition::Disconnected`), but node is already connected, thus cancelling new dial."),
             DialError::DialPeerConditionFalse(PeerCondition::NotDialing) => write!(f, "Dial error: dial condition was configured to only happen if there is currently no ongoing dialing attempt (`PeerCondition::NotDialing`), but a dial is in progress, thus cancelling new dial."),
+            DialError::DialPeerConditionFalse(PeerCondition::DisconnectedAndNotDialing) => write!(f, "Dial error: dial condition was configured to only happen when both disconnected (`PeerCondition::Disconnected`) and there is currently no ongoing dialing attempt (`PeerCondition::NotDialing`), but node is already connected or dial is in progress, thus cancelling new dial."),
             DialError::DialPeerConditionFalse(PeerCondition::Always) => unreachable!("Dial peer condition is by definition true."),
             DialError::Aborted => write!(
                 f,