Golang doozer.Client類代碼示例

func activate(st *store.Store, self string, c *doozer.Client) int64 {
	w := store.NewWatch(st, calGlob)

	for _, base := range store.Getdir(st, calDir) {
		p := calDir + "/" + base
		v, rev := st.Get(p)
		if rev != store.Dir && v[0] == "" {
			seqn, err := c.Set(p, rev, []byte(self))
			if err != nil {
				log.Println(err)
				continue
			}

			w.Stop()
			return seqn
		}
	}

	for ev := range w.C {
		// TODO ev.IsEmpty()
		if ev.IsSet() && ev.Body == "" {
			seqn, err := c.Set(ev.Path, ev.Rev, []byte(self))
			if err != nil {
				log.Println(err)
				continue
			}
			w.Stop()
			return seqn
		}
	}

	return 0
}

// Find possible addresses for cluster named name.
func lookup(b *doozer.Client, name string) (as []string) {
	info, err := b.Walk("/ctl/ns/"+name+"/*", nil, 0, -1)
	if err != nil {
		panic(err)
	}
	for _, e := range info {
		as = append(as, string(e.Body))
	}
	return as
}

// Elect chooses a seed node, and returns a connection to a cal.
// If this process is the seed, returns nil.
func elect(name, id, laddr string, b *doozer.Client) *doozer.Client {
	// advertise our presence, since we might become a cal
	nspath := "/ctl/ns/" + name + "/" + id
	r, err := b.Set(nspath, 0, []byte(laddr))
	if err != nil {
		panic(err)
	}

	// fight to be the seed
	_, err = b.Set("/ctl/boot/"+name, 0, []byte(id))
	switch err {
	case doozer.ErrOldRev:
		// we lost, lookup addresses again
		cl := lookupAndAttach(b, name)
		if cl == nil {
			panic("failed to attach after losing election")
		}

		// also delete our entry, since we're not officially a cal yet.
		// it gets set again in peer.Main when we become a cal.
		err := b.Del(nspath, r)
		if err != nil {
			panic(err)
		}

		return cl
	case nil:
		return nil // we are the seed node -- don't attach
	}
	panic(err)
}

func Main(clusterName, self, baddr string, cl *doozer.Client, udpConn net.PacketConn, listener, webListener net.Listener, pulseInterval, fillDelay, kickTimeout int64) {
	listenAddr := listener.Addr().String()

	var activateSeqn int64
	useSelf := make(chan bool, 1)

	st := store.New()
	pr := &proposer{
		seqns: make(chan int64, alpha),
		props: make(chan *consensus.Prop),
		st:    st,
	}

	calSrv := func() {
		go gc.Pulse(self, st.Seqns, pr, pulseInterval)
		go gc.Clean(st, 360000, time.Tick(1e9))
	}

	if cl == nil { // we are the only node in a new cluster
		set(st, "/ctl/name", clusterName, store.Missing)
		set(st, "/ctl/node/"+self+"/addr", listenAddr, store.Missing)
		set(st, "/ctl/node/"+self+"/hostname", os.Getenv("HOSTNAME"), store.Missing)
		set(st, "/ctl/node/"+self+"/version", Version, store.Missing)
		set(st, "/ctl/cal/0", self, store.Missing)
		calSrv()
		close(useSelf)
	} else {
		setC(cl, "/ctl/node/"+self+"/addr", listenAddr, store.Clobber)
		setC(cl, "/ctl/node/"+self+"/hostname", os.Getenv("HOSTNAME"), store.Clobber)
		setC(cl, "/ctl/node/"+self+"/version", Version, store.Clobber)

		rev, err := cl.Rev()
		if err != nil {
			panic(err)
		}

		walk, err := cl.Walk("/**", &rev, nil, nil)
		if err != nil {
			panic(err)
		}

		watch, err := cl.Watch("/**", rev+1)
		if err != nil {
			panic(err)
		}

		go follow(st.Ops, watch.C)
		follow(st.Ops, walk.C)
		st.Flush()
		ch, err := st.Wait(rev + 1)
		if err == nil {
			<-ch
		}

		go func() {
			activateSeqn = activate(st, self, cl)
			calSrv()
			advanceUntil(cl, st.Seqns, activateSeqn+alpha)
			err := watch.Cancel()
			if err != nil {
				panic(err)
			}
			close(useSelf)
			if baddr != "" {
				b := doozer.New("<boot>", baddr)
				setC(
					b,
					"/ctl/ns/"+clusterName+"/"+self,
					listenAddr,
					store.Missing,
				)
			}
		}()
	}

	start := <-st.Seqns
	cmw := st.Watch(store.Any)
	in := make(chan consensus.Packet, 50)
	out := make(chan consensus.Packet, 50)

	consensus.NewManager(self, start, alpha, in, out, st.Ops, pr.seqns, pr.props, cmw, fillDelay, st)

	if cl == nil {
		// Skip ahead alpha steps so that the registrar can provide a
		// meaningful cluster.
		for i := start + 1; i < start+alpha+1; i++ {
			st.Ops <- store.Op{i, store.Nop}
		}
	}

	shun := make(chan string, 3) // sufficient for a cluster of 7

	go member.Clean(shun, st, pr)

	sv := &server.Server{listenAddr, st, pr, self, alpha}

	go sv.Serve(listener, useSelf)

	if webListener != nil {
		web.Store = st
//.........這裏部分代碼省略.........

func setC(cl *doozer.Client, path, body string, rev int64) {
	_, err := cl.Set(path, rev, []byte(body))
	if err != nil {
		panic(err)
	}
}

func advanceUntil(cl *doozer.Client, ver <-chan int64, done int64) {
	for <-ver < done {
		cl.Nop()
	}
}