Refresh TTL; prune expired nodes.

registry/memory/memory.go

@@ -3,6 +3,7 @@ package memory
 
 import (
 	"context"
+	"strings"
 	"sync"
 	"time"
 
@@ -12,13 +13,15 @@ import (
 )
 
 var (
-	timeout = time.Millisecond * 10
+	sendEventTime = 10 * time.Millisecond
+	ttlPruneTime  = 1 * time.Minute
+	DefaultTTL    = 1 * time.Minute
 )
 
 // node tracks node registration timestamp and TTL
 type node struct {
-	ts  time.Time
-	ttl time.Duration
+	lastSeen time.Time
+	ttl      time.Duration
 }
 
 type Registry struct {
@@ -44,12 +47,67 @@ func NewRegistry(opts ...registry.Option) registry.Registry {
 		services = make(map[string][]*registry.Service)
 	}
 
-	return &Registry{
+	reg := &Registry{
 		options:  options,
 		Services: services,
 		nodes:    make(map[string]*node),
 		Watchers: make(map[string]*Watcher),
 	}
+
+	go reg.ttlPrune()
+
+	return reg
+}
+
+// nodeTrackId returns a string we use to track a node of a given service
+func nodeTrackId(svcName, svcVersion, nodeId string) string {
+	return svcName + "+" + svcVersion + "+" + nodeId
+}
+
+func (m *Registry) ttlPrune() {
+	prune := time.NewTicker(ttlPruneTime)
+	defer prune.Stop()
+
+	for {
+		select {
+		case <-prune.C:
+			m.Lock()
+			for nodeTrackId, node := range m.nodes {
+				// if we exceed the TTL threshold we need to stop tracking the node
+				if time.Since(node.lastSeen) > node.ttl {
+					// split nodeTrackID into service Name, Version and Node Id
+					trackIdSplit := strings.Split(nodeTrackId, "+")
+					svcName, svcVersion, nodeId := trackIdSplit[0], trackIdSplit[1], trackIdSplit[2]
+					log.Logf("TTL threshold reached for node %s for service %s", nodeId, svcName)
+					// we need to find a node that expired and delete it from service nodes
+					if _, ok := m.Services[svcName]; ok {
+						for _, service := range m.Services[svcName] {
+							if service.Version != svcVersion {
+								continue
+							}
+							// find expired service node and delete it
+							var nodes []*registry.Node
+							for _, n := range service.Nodes {
+								var del bool
+								if n.Id == nodeId {
+									del = true
+								}
+								if !del {
+									nodes = append(nodes, n)
+								}
+							}
+							service.Nodes = nodes
+						}
+					}
+					// stop tracking the node
+					delete(m.nodes, nodeTrackId)
+				}
+			}
+			m.Unlock()
+		}
+	}
+
+	return
 }
 
 func (m *Registry) sendEvent(r *registry.Result) {
@@ -70,7 +128,7 @@ func (m *Registry) sendEvent(r *registry.Result) {
 		default:
 			select {
 			case w.res <- r:
-			case <-time.After(timeout):
+			case <-time.After(sendEventTime):
 			}
 		}
 	}
@@ -125,14 +183,19 @@ func (m *Registry) Register(s *registry.Service, opts ...registry.RegisterOption
 		o(&options)
 	}
 
+	// if no TTL has been set, set it to DefaultTTL
+	if options.TTL.Seconds() == 0.0 {
+		options.TTL = DefaultTTL
+	}
+
 	if service, ok := m.Services[s.Name]; !ok {
 		m.Services[s.Name] = []*registry.Service{s}
 		// add all nodes into nodes map to track their TTL
 		for _, n := range s.Nodes {
 			log.Logf("Tracking node %s for service %s", n.Id, s.Name)
-			m.nodes[s.Name+n.Id] = &node{
-				ts:  time.Now(),
-				ttl: options.TTL,
+			m.nodes[nodeTrackId(s.Name, s.Version, n.Id)] = &node{
+				lastSeen: time.Now(),
+				ttl:      options.TTL,
 			}
 		}
 		go m.sendEvent(&registry.Result{Action: "update", Service: s})
@@ -159,9 +222,9 @@ func (m *Registry) Register(s *registry.Service, opts ...registry.RegisterOption
 			// we know s is the new [version of] service; we need to strart tracking its nodes
 			for _, n := range s.Nodes {
 				log.Logf("Tracking node %s for service %s", n.Id, s.Name)
-				m.nodes[s.Name+n.Id] = &node{
-					ts:  time.Now(),
-					ttl: options.TTL,
+				m.nodes[nodeTrackId(s.Name, s.Version, n.Id)] = &node{
+					lastSeen: time.Now(),
+					ttl:      options.TTL,
 				}
 			}
 			go m.sendEvent(&registry.Result{Action: "update", Service: s})
@@ -181,9 +244,9 @@ func (m *Registry) Register(s *registry.Service, opts ...registry.RegisterOption
 					}
 					if !found {
 						log.Logf("Tracking node %s for service %s", n.Id, s.Name)
-						m.nodes[s.Name+n.Id] = &node{
-							ts:  time.Now(),
-							ttl: options.TTL,
+						m.nodes[nodeTrackId(s.Name, s.Version, n.Id)] = &node{
+							lastSeen: time.Now(),
+							ttl:      options.TTL,
 						}
 					}
 				}
@@ -191,6 +254,15 @@ func (m *Registry) Register(s *registry.Service, opts ...registry.RegisterOption
 				go m.sendEvent(&registry.Result{Action: "update", Service: s})
 				return nil
 			}
+			// refresh the timestamp and TTL of the service node
+			for _, n := range s.Nodes {
+				trackId := nodeTrackId(s.Name, s.Version, n.Id)
+				log.Logf("Refreshing TTL for node %s for service %s", n.Id, s.Name)
+				if trackedNode, ok := m.nodes[trackId]; ok {
+					trackedNode.lastSeen = time.Now()
+					trackedNode.ttl = options.TTL
+				}
+			}
 		}
 	}
 
@@ -218,7 +290,7 @@ func (m *Registry) Deregister(s *registry.Service) error {
 		if service := registry.Remove(service, []*registry.Service{s}); len(service) == 0 {
 			id := svcNodes[s.Name][s.Version][0]
 			log.Logf("Stopped tracking node %s for service %s", id, s.Name)
-			delete(m.nodes, s.Name+id)
+			delete(m.nodes, nodeTrackId(s.Name, s.Version, id))
 			delete(m.Services, s.Name)
 		} else {
 			// find out which nodes have been removed
@@ -233,7 +305,7 @@ func (m *Registry) Deregister(s *registry.Service) error {
 					}
 					if !found {
 						log.Logf("Stopped tracking node %s for service %s", id, s.Name)
-						delete(m.nodes, s.Name+id)
+						delete(m.nodes, nodeTrackId(s.Name, s.Version, id))
 					}
 				}
 				m.Services[s.Name] = service