Add PeerList.Remove to remove peers

This removes a peer from a specific peer list. It does not affect any
existing connections to the peer.

If the peer is not reference from any other peer lists, and has no
connections, then it will get GC'd.

peer.go

@@ -37,6 +37,9 @@ var (
 	// ErrNoPeers indicates that there are no peers.
 	ErrNoPeers = errors.New("no peers available")
 
+	// ErrPeerNotFound indicates that the specified peer was not found.
+	ErrPeerNotFound = errors.New("peer not found")
+
 	peerRng = NewRand(time.Now().UnixNano())
 )
 
@@ -122,6 +125,23 @@ func (l *PeerList) Get(prevSelected map[string]struct{}) (*Peer, error) {
 	return peer, nil
 }
 
+// Remove removes a peer from the peer list. It returns an error if the peer cannot be found.
+// Remove does not affect connections to the peer in any way.
+func (l *PeerList) Remove(hostPort string) error {
+	l.Lock()
+	defer l.Unlock()
+
+	p, ok := l.peersByHostPort[hostPort]
+	if !ok {
+		return ErrPeerNotFound
+	}
+
+	p.delSC()
+	delete(l.peersByHostPort, hostPort)
+	l.peerHeap.removePeer(p)
+
+	return nil
+}
 func (l *PeerList) choosePeer(prevSelected map[string]struct{}, avoidHost bool) *Peer {
 	var psPopList []*peerScore
 	var ps *peerScore
@@ -327,6 +347,13 @@ func (p *Peer) addSC() {
 	p.Unlock()
 }
 
+// delSC removes a reference to a peer from a subchannel (e.g. peer list).
+func (p *Peer) delSC() {
+	p.Lock()
+	p.scCount--
+	p.Unlock()
+}
+
 // canRemove returns whether this peer can be safely removed from the root peer list.
 func (p *Peer) canRemove() bool {
 	p.RLock()

peer_test.go

@@ -180,13 +180,32 @@ func TestOutboundPeerNotAdded(t *testing.T) {
 	})
 }
 
+func TestRemovePeerNotFound(t *testing.T) {
+	peers := testutils.NewClient(t, nil).Peers()
+	peers.Add("1.1.1.1:1")
+	assert.Error(t, peers.Remove("not-found"), "Remove should fa")
+	assert.NoError(t, peers.Remove("1.1.1.1:1"), "Remove shouldn't fail for existing peer")
+}
+
 func TestPeerRemovedFromRootPeers(t *testing.T) {
 	tests := []struct {
-		addHostPort bool
-		expectFound bool
+		addHostPort    bool
+		removeHostPort bool
+		expectFound    bool
 	}{
-		{true, true},
-		{false, false},
+		{
+			addHostPort: true,
+			expectFound: true,
+		},
+		{
+			addHostPort:    true,
+			removeHostPort: true,
+			expectFound:    false,
+		},
+		{
+			addHostPort: false,
+			expectFound: false,
+		},
 	}
 
 	ctx, cancel := NewContext(time.Second)
@@ -203,6 +222,11 @@ func TestPeerRemovedFromRootPeers(t *testing.T) {
 
 			assert.NoError(t, ch.Ping(ctx, hostPort), "Ping failed")
 
+			if tt.removeHostPort {
+				require.NoError(t, server.Peers().Remove(clientHP), "Failed to remove peer")
+
+			}
+
 			waitTillInboundEmpty(t, server, clientHP, func() {
 				ch.Close()
 			})