Add gossip timeout for dead nodes and make kRandomNodes pluggable

config.go

@@ -126,8 +126,12 @@ type Config struct {
 	// per GossipInterval. Increasing this number causes the gossip messages
 	// to propagate across the cluster more quickly at the expense of
 	// increased bandwidth.
-	GossipInterval time.Duration
-	GossipNodes    int
+	//
+	// GossipToTheDeadTime is the interval after which a node has died that
+	// we will still try to gossip to it. This gives it a chance to refute.
+	GossipInterval      time.Duration
+	GossipNodes         int
+	GossipToTheDeadTime time.Duration
 
 	// EnableCompression is used to control message compression. This can
 	// be used to reduce bandwidth usage at the cost of slightly more CPU
@@ -212,8 +216,9 @@ func DefaultLANConfig() *Config {
 		DisableTcpPings:         false,                  // TCP pings are safe, even with mixed versions
 		AwarenessMaxMultiplier:  8,                      // Probe interval backs off to 8 seconds
 
-		GossipNodes:    3,                      // Gossip to 3 nodes
-		GossipInterval: 200 * time.Millisecond, // Gossip more rapidly
+		GossipNodes:         3,                      // Gossip to 3 nodes
+		GossipInterval:      200 * time.Millisecond, // Gossip more rapidly
+		GossipToTheDeadTime: 30 * time.Second,       // Same as push/pull
 
 		EnableCompression: true, // Enable compression by default
 
@@ -238,6 +243,7 @@ func DefaultWANConfig() *Config {
 	conf.ProbeInterval = 5 * time.Second
 	conf.GossipNodes = 4 // Gossip less frequently, but to an additional node
 	conf.GossipInterval = 500 * time.Millisecond
+	conf.GossipToTheDeadTime = 60 * time.Second
 	return conf
 }
 
@@ -254,6 +260,7 @@ func DefaultLocalConfig() *Config {
 	conf.ProbeTimeout = 200 * time.Millisecond
 	conf.ProbeInterval = time.Second
 	conf.GossipInterval = 100 * time.Millisecond
+	conf.GossipToTheDeadTime = 15 * time.Second
 	return conf
 }
 

state.go

@@ -310,8 +310,11 @@ func (m *Memberlist) probeNode(node *nodeState) {
 
 	// Get some random live nodes.
 	m.nodeLock.RLock()
-	excludes := []string{m.config.Name, node.Name}
-	kNodes := kRandomNodes(m.config.IndirectChecks, excludes, m.nodes)
+	kNodes := kRandomNodes(m.config.IndirectChecks, m.nodes, func(n *nodeState) bool {
+		return n.Name == m.config.Name ||
+			n.Name == node.Name ||
+			n.State != stateAlive
+	})
 	m.nodeLock.RUnlock()
 
 	// Attempt an indirect ping.
@@ -460,10 +463,24 @@ func (m *Memberlist) resetNodes() {
 func (m *Memberlist) gossip() {
 	defer metrics.MeasureSince([]string{"memberlist", "gossip"}, time.Now())
 
-	// Get some random live nodes
+	// Get some random live, suspect, or recently dead nodes
 	m.nodeLock.RLock()
-	excludes := []string{m.config.Name}
-	kNodes := kRandomNodes(m.config.GossipNodes, excludes, m.nodes)
+	kNodes := kRandomNodes(m.config.GossipNodes, m.nodes, func(n *nodeState) bool {
+		if n.Name == m.config.Name {
+			return true
+		}
+
+		switch n.State {
+		case stateAlive, stateSuspect:
+			return false
+
+		case stateDead:
+			return time.Since(n.StateChange) > m.config.GossipToTheDeadTime
+
+		default:
+			return true
+		}
+	})
 	m.nodeLock.RUnlock()
 
 	// Compute the bytes available
@@ -497,8 +514,10 @@ func (m *Memberlist) gossip() {
 func (m *Memberlist) pushPull() {
 	// Get a random live node
 	m.nodeLock.RLock()
-	excludes := []string{m.config.Name}
-	nodes := kRandomNodes(1, excludes, m.nodes)
+	nodes := kRandomNodes(1, m.nodes, func(n *nodeState) bool {
+		return n.Name == m.config.Name ||
+			n.State != stateAlive
+	})
 	m.nodeLock.RUnlock()
 
 	// If no nodes, bail

state_test.go

@@ -1680,6 +1680,54 @@ func TestMemberlist_Gossip(t *testing.T) {
 	}
 }
 
+func TestMemberlist_GossipToDead(t *testing.T) {
+	ch := make(chan NodeEvent, 2)
+
+	addr1 := getBindAddr()
+	addr2 := getBindAddr()
+	ip1 := []byte(addr1)
+	ip2 := []byte(addr2)
+
+	m1 := HostMemberlist(addr1.String(), t, func(c *Config) {
+		c.GossipInterval = time.Millisecond
+		c.GossipToTheDeadTime = 100 * time.Millisecond
+	})
+	m2 := HostMemberlist(addr2.String(), t, func(c *Config) {
+		c.Events = &ChannelEventDelegate{ch}
+	})
+
+	defer m1.Shutdown()
+	defer m2.Shutdown()
+
+	a1 := alive{Node: addr1.String(), Addr: ip1, Port: 7946, Incarnation: 1}
+	m1.aliveNode(&a1, nil, true)
+	a2 := alive{Node: addr2.String(), Addr: ip2, Port: 7946, Incarnation: 1}
+	m1.aliveNode(&a2, nil, false)
+
+	// Shouldn't send anything to m2 here, node has been dead for 2x the GossipToTheDeadTime
+	m1.nodeMap[addr2.String()].State = stateDead
+	m1.nodeMap[addr2.String()].StateChange = time.Now().Add(-200 * time.Millisecond)
+	m1.gossip()
+
+	select {
+	case <-ch:
+		t.Fatalf("shouldn't get gossip")
+	case <-time.After(50 * time.Millisecond):
+	}
+
+	// Should gossip to m2 because its state has changed within GossipToTheDeadTime
+	m1.nodeMap[addr2.String()].StateChange = time.Now().Add(-20 * time.Millisecond)
+	m1.gossip()
+
+	for i := 0; i < 2; i++ {
+		select {
+		case <-ch:
+		case <-time.After(50 * time.Millisecond):
+			t.Fatalf("timeout")
+		}
+	}
+}
+
 func TestMemberlist_PushPull(t *testing.T) {
 	addr1 := getBindAddr()
 	addr2 := getBindAddr()

util.go

@@ -207,9 +207,10 @@ func moveDeadNodes(nodes []*nodeState) int {
 	return n - numDead
 }
 
-// kRandomNodes is used to select up to k random nodes, excluding a given
-// node and any non-alive nodes. It is possible that less than k nodes are returned.
-func kRandomNodes(k int, excludes []string, nodes []*nodeState) []*nodeState {
+// kRandomNodes is used to select up to k random nodes, excluding any nodes where
+// the filter function returns true. It is possible that less than k nodes are
+// returned.
+func kRandomNodes(k int, nodes []*nodeState, filterFn func(*nodeState) bool) []*nodeState {
 	n := len(nodes)
 	kNodes := make([]*nodeState, 0, k)
 OUTER:
@@ -221,16 +222,9 @@ OUTER:
 		idx := randomOffset(n)
 		node := nodes[idx]
 
-		// Exclude node if match
-		for _, exclude := range excludes {
-			if node.Name == exclude {
-				continue OUTER
-			}
-		}
-
-		// Exclude if not alive
-		if node.State != stateAlive {
-			continue
+		// Give the filter a shot at it.
+		if filterFn != nil && filterFn(node) {
+			continue OUTER
 		}
 
 		// Check if we have this node already

util_test.go

@@ -295,9 +295,16 @@ func TestKRandomNodes(t *testing.T) {
 		})
 	}
 
-	s1 := kRandomNodes(3, []string{"test0"}, nodes)
-	s2 := kRandomNodes(3, []string{"test0"}, nodes)
-	s3 := kRandomNodes(3, []string{"test0"}, nodes)
+	filterFunc := func(n *nodeState) bool {
+		if n.Name == "test0" || n.State != stateAlive {
+			return true
+		}
+		return false
+	}
+
+	s1 := kRandomNodes(3, nodes, filterFunc)
+	s2 := kRandomNodes(3, nodes, filterFunc)
+	s3 := kRandomNodes(3, nodes, filterFunc)
 
 	if reflect.DeepEqual(s1, s2) {
 		t.Fatalf("unexpected equal")