Golang doozer.Conn類代碼示例

func set(cl *doozer.Conn, id, iter int, path string, value []byte, f cb) {
	for i := 0; i < iter; i++ {
		s := time.Nanoseconds()
		rev, err := cl.Set(path, math.MaxInt64, value)
		e := time.Nanoseconds()
		f(id, i, rev, s, e, err)
	}
}

func watch(conn *doozer.Conn, events chan doozer.Event, revs chan int64) {
	for {
		rev := <-revs
		event, err := conn.Wait("/*", rev)
		if err != nil {
			panic("error waiting for event, bailing")
		}
		revs <- event.Rev + 1
		events <- event
	}
}

func activate(st *store.Store, self string, c *doozer.Conn) int64 {
	rev, _ := st.Snap()

	entries := store.Getdir(st, calDir)
	base := entries[len(entries)-1]
	index, _ := strconv.ParseInt(base, 10, 32)
	index += 1
	p := calDir + "/" + strconv.Itoa(int(index))
	seqn, err := c.Set(p, rev, []byte(self))

	if err != nil {
		panic(err)
	}

	// 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
	// 		}

	// 		return seqn
	// 	}
	// }

	// for {
	// 	ch, err := st.Wait(calGlob, rev+1)
	// 	if err != nil {
	// 		panic(err)
	// 	}
	// 	ev, ok := <-ch
	// 	if !ok {
	// 		panic(io.EOF)
	// 	}
	// 	rev = ev.Rev
	// 	// 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
	// 		}
	// 		return seqn
	// 	} else if ev.IsSet() && ev.Body == self {
	// 		return ev.Seqn
	// 	}
	// }

	return seqn
}

func waitFor(cl *doozer.Conn, path string) {
	var rev int64
	for {
		ev, err := cl.Wait(path, rev)
		if err != nil {
			panic(err)
		}
		if ev.IsSet() && len(ev.Body) > 0 {
			break
		}
		rev = ev.Rev + 1
	}
}

// Find possible addresses for cluster named name.
func lookup(b *doozer.Conn, name string) (as []string) {
	rev, err := b.Rev()
	if err != nil {
		panic(err)
	}

	info, err := b.Walk("/ctl/ns/"+name+"/*", rev, 0, -1)
	if err != nil {
		panic(err)
	}
	for _, e := range info {
		as = append(as, string(e.Body))
	}
	return as
}

func activate(st *store.Store, self string, c *doozer.Conn) int64 {
	rev, _ := st.Snap()

	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
			}

			return seqn
		}
	}

	for {
		ch, err := st.Wait(calGlob, rev+1)
		if err != nil {
			panic(err)
		}
		ev, ok := <-ch
		if !ok {
			panic(io.EOF)
		}
		rev = ev.Rev
		// 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
			}
			return seqn
		} else if ev.IsSet() && ev.Body == self {
			return ev.Seqn
		}
	}

	return 0
}

func follow(st *store.Store, cl *doozer.Conn, rev int64, stop chan bool) {
	for {
		ev, err := cl.Wait("/**", rev)
		if err != nil {
			panic(err)
		}

		// store.Clobber is okay here because the event
		// has already passed through another store
		mut := store.MustEncodeSet(ev.Path, string(ev.Body), store.Clobber)
		st.Ops <- store.Op{ev.Rev, mut}
		rev = ev.Rev + 1

		select {
		case <-stop:
			return
		default:
		}
	}
}

// wait waits on a changes for the fiven file starting at the given
// revision from the given doozer connection. It sends updated peer
// lists on the returned channel.
func wait(d *doozer.Conn, file string, rev *int64) chan []string {
	c := make(chan []string, 1)
	cur := *rev
	go func() {
		for {
			// Wait for the change.
			e, err := d.Wait(file, cur+1)
			if err != nil {
				log.Println("waiting failed (no longer watching):", err)
				close(c)
				return
			}
			// Update the revision and send the change on the channel.
			atomic.CompareAndSwapInt64(rev, cur, e.Rev)
			cur = e.Rev
			c <- strings.Split(string(e.Body), " ")
		}
	}()

	return c
}

// 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.Conn) *doozer.Conn {
	// 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))
	if err, ok := err.(*doozer.Error); ok && err.Err == 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
	} else if err != nil {
		panic(err)
	}

	return nil // we are the seed node -- don't attach
}

// Find possible addresses for cluster named name.
func lookup(b *doozer.Conn, name string) (as []string) {
	rev, err := b.Rev()
	if err != nil {
		panic(err)
	}

	path := "/ctl/ns/" + name
	names, err := b.Getdir(path, rev, 0, -1)
	if err == doozer.ErrNoEnt {
		return nil
	} else if err, ok := err.(*doozer.Error); ok && err.Err == doozer.ErrNoEnt {
		return nil
	} else if err != nil {
		panic(err)
	}

	path += "/"
	for _, name := range names {
		body, _, err := b.Get(path+name, &rev)
		if err != nil {
			panic(err)
		}
		as = append(as, string(body))
	}
	return as
}

// watch updates the peer list of servers based on changes to the
// doozer configuration or signals from the OS.
func watch(d *doozer.Conn) {
	peerFile := "/peers"
	var peers []string
	var rev int64

	// Run the initial get.
	data, rev, err := d.Get(peerFile, nil)
	if err != nil {
		log.Println("initial peer list get:", err)
		log.Println("using empty set to start")
		peers = []string{}
	} else {
		peers = strings.Split(string(data), " ")
	}

	// Add myself to the list.
	peers = append(peers, "http://"+addr)
	rev, err = d.Set(peerFile, rev,
		[]byte(strings.Join(peers, " ")))
	if err != nil {
		log.Println("unable to add myself to the peer list (no longer watching).")
		return
	}
	pool.Set(peers...)
	log.Println("added myself to the peer list.")

	// Setup signal handling to deal with ^C and others.
	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, os.Interrupt, os.Kill)

	// Get the channel that's listening for changes.
	updates := wait(d, peerFile, &rev)

	for {
		select {
		case <-sigs:
			// Remove ourselves from the peer list and exit.
			for i, peer := range peers {
				if peer == "http://"+addr {
					peers = append(peers[:i], peers[i+1:]...)
					d.Set(peerFile, rev, []byte(strings.Join(peers, " ")))
					log.Println("removed myself from peer list before exiting.")
				}
			}
			os.Exit(1)

		case update, ok := <-updates:
			// If the channel was closed, we should stop selecting on it.
			if !ok {
				updates = nil
				continue
			}

			// Otherwise, update the peer list.
			peers = update
			log.Println("got new peer list:", strings.Join(peers, " "))
			pool.Set(peers...)
		}
	}
}

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

	canWrite := make(chan bool, 1)
	in := make(chan consensus.Packet, 50)
	out := make(chan consensus.Packet, 50)

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

	calSrv := func(start int64) {
		go gc.Pulse(self, st.Seqns, pr, pulseInterval)
		go gc.Clean(st, hi, time.Tick(1e9))
		var m consensus.Manager
		m.Self = self
		m.DefRev = start
		m.Alpha = alpha
		m.In = in
		m.Out = out
		m.Ops = st.Ops
		m.PSeqn = pr.seqns
		m.Props = pr.props
		m.TFill = fillDelay
		m.Store = st
		m.Ticker = time.Tick(10e6)
		go m.Run()
	}

	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(<-st.Seqns)
		// Skip ahead alpha steps so that the registrar can provide a
		// meaningful cluster.
		for i := 0; i < alpha; i++ {
			st.Ops <- store.Op{1 + <-st.Seqns, store.Nop}
		}
		canWrite <- true
	} 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)
		}

		stop := make(chan bool, 1)
		go follow(st, cl, rev+1, stop)

		errs := make(chan os.Error)
		go func() {
			e, ok := <-errs
			if ok {
				panic(e)
			}
		}()
		doozer.Walk(cl, rev, "/", cloner{st.Ops, cl}, errs)
		close(errs)
		st.Flush()

		ch, err := st.Wait(store.Any, rev+1)
		if err == nil {
			<-ch
		}

		go func() {
			n := activate(st, self, cl)
			calSrv(n)
			advanceUntil(cl, st.Seqns, n+alpha)
			stop <- true
			canWrite <- true
			if buri != "" {
				b, err := doozer.DialUri(buri, "")
				if err != nil {
					panic(err)
				}
				setC(
					b,
					"/ctl/ns/"+clusterName+"/"+self,
					listenAddr,
					store.Missing,
				)
			}
		}()
	}

	shun := make(chan string, 3) // sufficient for a cluster of 7
	go member.Clean(shun, st, pr)
	go server.ListenAndServe(listener, canWrite, st, pr, rwsk, rosk)

	if rwsk == "" && rosk == "" && webListener != nil {
//.........這裏部分代碼省略.........

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

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

func Main(clusterName, self, buri, rwsk, rosk string, cl *doozer.Conn, udpConn *net.UDPConn, listener, webListener net.Listener, pulseInterval, fillDelay, kickTimeout int64, hi int64) {
	listenAddr := listener.Addr().String()

	canWrite := make(chan bool, 1)
	in := make(chan consensus.Packet, 50)
	out := make(chan consensus.Packet, 50)

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

	calSrv := func(start int64) {
		go gc.Pulse(self, st.Seqns, pr, pulseInterval)
		go gc.Clean(st, hi, time.Tick(1e9))
		var m consensus.Manager
		m.Self = self
		m.DefRev = start
		m.Alpha = alpha
		m.In = in
		m.Out = out
		m.Ops = st.Ops
		m.PSeqn = pr.seqns
		m.Props = pr.props
		m.TFill = fillDelay
		m.Store = st
		m.Ticker = time.Tick(10e6)
		go m.Run()
	}

	hostname, err := os.Hostname()
	if err != nil {
		hostname = "unknown"
	}

	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", hostname, store.Missing)
		set(st, "/ctl/node/"+self+"/version", Version, store.Missing)
		set(st, "/ctl/cal/0", self, store.Missing)
		if buri == "" {
			set(st, "/ctl/ns/"+clusterName+"/"+self, listenAddr, store.Missing)
		}
		calSrv(<-st.Seqns)
		// Skip ahead alpha steps so that the registrar can provide a
		// meaningful cluster.
		for i := 0; i < alpha; i++ {
			st.Ops <- store.Op{1 + <-st.Seqns, store.Nop}
		}
		canWrite <- true
		go setReady(pr, self)
	} else {
		setC(cl, "/ctl/node/"+self+"/addr", listenAddr, store.Clobber)
		setC(cl, "/ctl/node/"+self+"/hostname", hostname, store.Clobber)
		setC(cl, "/ctl/node/"+self+"/version", Version, store.Clobber)

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

		stop := make(chan bool, 1)
		go follow(st, cl, rev+1, stop)

		errs := make(chan error)
		go func() {
			e, ok := <-errs
			if ok {
				panic(e)
			}
		}()
		doozer.Walk(cl, rev, "/", cloner{st.Ops, cl, rev}, errs)
		close(errs)
		st.Flush()

		ch, err := st.Wait(store.Any, rev+1)
		if err == nil {
			<-ch
		}

		go func() {
			n := activate(st, self, cl)
			calSrv(n)
			advanceUntil(cl, st.Seqns, n+alpha)
			stop <- true
			canWrite <- true
			go setReady(pr, self)
			if buri != "" {
				b, err := doozer.DialUri(buri, "")
				if err != nil {
					panic(err)
				}
				setC(
					b,
					"/ctl/ns/"+clusterName+"/"+self,
					listenAddr,
					store.Missing,
//.........這裏部分代碼省略.........