From c845b3bd68a6daba4d09bbccb3dc049278371d48 Mon Sep 17 00:00:00 2001
From: Asim Aslam <asim@chuhnk.me>
Date: Thu, 9 Aug 2018 18:08:59 +0100
Subject: [PATCH] Add Init to registry

---
 gossip.go | 142 ++++++++++++++++++++++++++++++++----------------------
 1 file changed, 84 insertions(+), 58 deletions(-)

diff --git a/gossip.go b/gossip.go
index 358468c..2be2779 100644
--- a/gossip.go
+++ b/gossip.go
@@ -38,6 +38,7 @@ type gossipRegistry struct {
 	broadcasts *memberlist.TransmitLimitedQueue
 	updates    chan *update
 	options    registry.Options
+	member     *memberlist.Memberlist
 
 	sync.RWMutex
 	services map[string][]*registry.Service
@@ -64,6 +65,80 @@ func init() {
 	cmd.DefaultRegistries["gossip"] = NewRegistry
 }
 
+func configure(g *gossipRegistry, opts ...registry.Option) error {
+	addrs := func() []string {
+		var cAddrs []string
+		for _, addr := range g.options.Addrs {
+			if len(addr) > 0 {
+				cAddrs = append(cAddrs, addr)
+			}
+		}
+		return cAddrs
+	}
+
+	cAddrs := addrs()
+	hostname, _ := os.Hostname()
+
+	for _, o := range opts {
+		o(&g.options)
+	}
+
+	newAddrs := addrs()
+
+	// no new nodes and existing member. no configure
+	if (len(newAddrs) == len(cAddrs)) && g.member != nil {
+		return nil
+	}
+
+	// shutdown old member
+	if g.member != nil {
+		log.Logf("Shutdown old memberlist: %v", g.member.Shutdown())
+	}
+
+	cAddrs = newAddrs
+
+	broadcasts := &memberlist.TransmitLimitedQueue{
+		NumNodes: func() int {
+			return len(cAddrs)
+		},
+		RetransmitMult: 3,
+	}
+
+	c := memberlist.DefaultLocalConfig()
+	c.BindPort = 0
+	c.Name = hostname + "-" + uuid.NewUUID().String()
+	c.Delegate = &delegate{
+		updates:    g.updates,
+		broadcasts: broadcasts,
+	}
+
+	if g.options.Secure {
+		k, ok := g.options.Context.Value(contextSecretKey{}).([]byte)
+		if !ok {
+			k = DefaultKey
+		}
+		c.SecretKey = k
+	}
+
+	m, err := memberlist.Create(c)
+	if err != nil {
+		log.Fatalf("Error creating memberlist: %v", err)
+	}
+
+	if len(cAddrs) > 0 {
+		_, err := m.Join(cAddrs)
+		if err != nil {
+			log.Fatalf("Error joining members: %v", err)
+		}
+	}
+
+	g.broadcasts = broadcasts
+	g.member = m
+
+	log.Logf("Local memberlist node %s:%d\n", m.LocalNode().Addr, m.LocalNode().Port)
+	return nil
+}
+
 func addNodes(old, neu []*registry.Node) []*registry.Node {
 	for _, n := range neu {
 		var seen bool
@@ -342,6 +417,10 @@ func (m *gossipRegistry) run() {
 	}
 }
 
+func (m *gossipRegistry) Init(opts ...registry.Option) error {
+	return configure(m, opts...)
+}
+
 func (m *gossipRegistry) Options() registry.Options {
 	return m.options
 }
@@ -433,66 +512,13 @@ func (m *gossipRegistry) String() string {
 }
 
 func NewRegistry(opts ...registry.Option) registry.Registry {
-	var options registry.Options
-	for _, o := range opts {
-		o(&options)
-	}
-
-	cAddrs := []string{}
-	hostname, _ := os.Hostname()
-	updates := make(chan *update, 100)
-
-	for _, addr := range options.Addrs {
-		if len(addr) > 0 {
-			cAddrs = append(cAddrs, addr)
-		}
-	}
-
-	broadcasts := &memberlist.TransmitLimitedQueue{
-		NumNodes: func() int {
-			return len(cAddrs)
-		},
-		RetransmitMult: 3,
-	}
-
 	mr := &gossipRegistry{
-		options:    options,
-		broadcasts: broadcasts,
-		services:   make(map[string][]*registry.Service),
-		updates:    updates,
-		subs:       make(map[string]chan *registry.Result),
+		options:  registry.Options{},
+		updates:  make(chan *update, 100),
+		services: make(map[string][]*registry.Service),
+		subs:     make(map[string]chan *registry.Result),
 	}
-
+	configure(mr, opts...)
 	go mr.run()
-
-	c := memberlist.DefaultLocalConfig()
-	c.BindPort = 0
-	c.Name = hostname + "-" + uuid.NewUUID().String()
-	c.Delegate = &delegate{
-		updates:    updates,
-		broadcasts: broadcasts,
-	}
-
-	if options.Secure {
-		k, ok := options.Context.Value(contextSecretKey{}).([]byte)
-		if !ok {
-			k = DefaultKey
-		}
-		c.SecretKey = k
-	}
-
-	m, err := memberlist.Create(c)
-	if err != nil {
-		log.Fatalf("Error creating memberlist: %v", err)
-	}
-
-	if len(cAddrs) > 0 {
-		_, err := m.Join(cAddrs)
-		if err != nil {
-			log.Fatalf("Error joining members: %v", err)
-		}
-	}
-
-	log.Logf("Local memberlist node %s:%d\n", m.LocalNode().Addr, m.LocalNode().Port)
 	return mr
 }