Merge pull request #5483 from oasisprotocol/peternose/stable/23.0.x/b…

…ackport-5480

[BACKPORT/23.0.x] go/p2p/peermgmt: Find peers and connect only when needed

.cargo/audit.toml

@@ -2,4 +2,5 @@
 ignore = [
     "RUSTSEC-2020-0071", # Remove once upstream dependencies are updated.
     "RUSTSEC-2021-0124", # Remove once upstream dependencies are updated.
+    "RUSTSEC-2023-0071", # Does not affect our current use of the library.
 ]

.changelog/5480.bugfix.md

@@ -0,0 +1,5 @@
+go/p2p/peermgmt: Find peers and connect only when needed
+
+If we are already connected to a sufficient number of peers
+for a given topic or protocol, there's no need to retrieve
+additional peers from the registry or the seed node.

go/p2p/peermgmt/peermgr.go

@@ -366,11 +366,6 @@ func (m *PeerManager) connectPeers(ctx context.Context, registered bool) {
 		}()
 	}
 
-	var (
-		peerCh <-chan peer.AddrInfo
-		limit  int
-	)
-
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -379,30 +374,34 @@ func (m *PeerManager) connectPeers(ctx context.Context, registered bool) {
 
 		switch registered {
 		case true:
-			peerCh = m.registry.findProtocolPeers(ctx, p)
-			limit = d.min - connected
+			if limit := d.min - connected; limit > 0 {
+				peerCh := m.registry.findProtocolPeers(ctx, p)
+				connectPeers(peerCh, limit)
+			}
 		default:
-			peerCh = m.discovery.findPeers(ctx, string(p))
-			limit = d.total - connected
+			if limit := d.total - connected; limit > 0 {
+				peerCh := m.discovery.findPeers(ctx, string(p))
+				connectPeers(peerCh, limit)
+			}
 		}
-
-		connectPeers(peerCh, limit)
 	}
 
 	for t, d := range m.topics {
 		connected := m.NumTopicPeers(t)
 
 		switch registered {
 		case true:
-			peerCh = m.registry.findTopicPeers(ctx, t)
-			limit = d.min - connected
+			if limit := d.min - connected; limit > 0 {
+				peerCh := m.registry.findTopicPeers(ctx, t)
+				connectPeers(peerCh, limit)
+			}
 
 		default:
-			peerCh = m.discovery.findPeers(ctx, t)
-			limit = d.total - connected
+			if limit := d.total - connected; limit > 0 {
+				peerCh := m.discovery.findPeers(ctx, t)
+				connectPeers(peerCh, limit)
+			}
 		}
-
-		connectPeers(peerCh, limit)
 	}
 }