Initial support for getting the leader from Zookeeper.

Some tests included for making sure the JSON blob pulled from Zookeeper
is correct.

Updated client to be able to take Zookeeper json cluster config that is
currently being used in aurora (clusters.json usually located at
/etc/aurora/cluster.json).

Changed error messages to no longer have a period at the end as that was
throwing off printing of the error.

Modified samuel's ZK library slightly to stop verbose logging using a
NoOpLogger from stackoverflow.

vendor/github.com/samuel/go-zookeeper/LICENSE

@@ -0,0 +1,25 @@
+Copyright (c) 2013, Samuel Stauffer <samuel@descolada.com>
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright
+  notice, this list of conditions and the following disclaimer.
+* Redistributions in binary form must reproduce the above copyright
+  notice, this list of conditions and the following disclaimer in the
+  documentation and/or other materials provided with the distribution.
+* Neither the name of the author nor the
+  names of its contributors may be used to endorse or promote products
+  derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/github.com/samuel/go-zookeeper/zk/conn.go

@@ -0,0 +1,935 @@
+// Package zk is a native Go client library for the ZooKeeper orchestration service.
+package zk
+
+/*
+TODO:
+* make sure a ping response comes back in a reasonable time
+
+Possible watcher events:
+* Event{Type: EventNotWatching, State: StateDisconnected, Path: path, Err: err}
+*/
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+// ErrNoServer indicates that an operation cannot be completed
+// because attempts to connect to all servers in the list failed.
+var ErrNoServer = errors.New("zk: could not connect to a server")
+
+// ErrInvalidPath indicates that an operation was being attempted on
+// an invalid path. (e.g. empty path)
+var ErrInvalidPath = errors.New("zk: invalid path")
+
+// DefaultLogger uses the stdlib log package for logging.
+var DefaultLogger Logger = defaultLogger{}
+
+const (
+	bufferSize      = 1536 * 1024
+	eventChanSize   = 6
+	sendChanSize    = 16
+	protectedPrefix = "_c_"
+)
+
+type watchType int
+
+const (
+	watchTypeData  = iota
+	watchTypeExist = iota
+	watchTypeChild = iota
+)
+
+type watchPathType struct {
+	path  string
+	wType watchType
+}
+
+type Dialer func(network, address string, timeout time.Duration) (net.Conn, error)
+
+// Logger is an interface that can be implemented to provide custom log output.
+type Logger interface {
+	Printf(string, ...interface{})
+}
+
+// NoOp logger -- http://stackoverflow.com/questions/10571182/go-disable-a-log-logger
+type NopLogger struct {
+	*log.Logger
+}
+
+func (l NopLogger) Printf(string, ...interface{}) {
+	// noop
+}
+
+type Conn struct {
+	lastZxid         int64
+	sessionID        int64
+	state            State // must be 32-bit aligned
+	xid              uint32
+	sessionTimeoutMs int32 // session timeout in milliseconds
+	passwd           []byte
+
+	dialer         Dialer
+	hostProvider   HostProvider
+	serverMu       sync.Mutex // protects server
+	server         string     // remember the address/port of the current server
+	conn           net.Conn
+	eventChan      chan Event
+	shouldQuit     chan struct{}
+	pingInterval   time.Duration
+	recvTimeout    time.Duration
+	connectTimeout time.Duration
+
+	sendChan     chan *request
+	requests     map[int32]*request // Xid -> pending request
+	requestsLock sync.Mutex
+	watchers     map[watchPathType][]chan Event
+	watchersLock sync.Mutex
+
+	// Debug (used by unit tests)
+	reconnectDelay time.Duration
+
+	logger Logger
+}
+
+// connOption represents a connection option.
+type connOption func(c *Conn)
+
+type request struct {
+	xid        int32
+	opcode     int32
+	pkt        interface{}
+	recvStruct interface{}
+	recvChan   chan response
+
+	// Because sending and receiving happen in separate go routines, there's
+	// a possible race condition when creating watches from outside the read
+	// loop. We must ensure that a watcher gets added to the list synchronously
+	// with the response from the server on any request that creates a watch.
+	// In order to not hard code the watch logic for each opcode in the recv
+	// loop the caller can use recvFunc to insert some synchronously code
+	// after a response.
+	recvFunc func(*request, *responseHeader, error)
+}
+
+type response struct {
+	zxid int64
+	err  error
+}
+
+type Event struct {
+	Type   EventType
+	State  State
+	Path   string // For non-session events, the path of the watched node.
+	Err    error
+	Server string // For connection events
+}
+
+// HostProvider is used to represent a set of hosts a ZooKeeper client should connect to.
+// It is an analog of the Java equivalent:
+// http://svn.apache.org/viewvc/zookeeper/trunk/src/java/main/org/apache/zookeeper/client/HostProvider.java?view=markup
+type HostProvider interface {
+	// Init is called first, with the servers specified in the connection string.
+	Init(servers []string) error
+	// Len returns the number of servers.
+	Len() int
+	// Next returns the next server to connect to. retryStart will be true if we've looped through
+	// all known servers without Connected() being called.
+	Next() (server string, retryStart bool)
+	// Notify the HostProvider of a successful connection.
+	Connected()
+}
+
+// ConnectWithDialer establishes a new connection to a pool of zookeeper servers
+// using a custom Dialer. See Connect for further information about session timeout.
+// This method is deprecated and provided for compatibility: use the WithDialer option instead.
+func ConnectWithDialer(servers []string, sessionTimeout time.Duration, dialer Dialer) (*Conn, <-chan Event, error) {
+	return Connect(servers, sessionTimeout, WithDialer(dialer))
+}
+
+// Connect establishes a new connection to a pool of zookeeper
+// servers. The provided session timeout sets the amount of time for which
+// a session is considered valid after losing connection to a server. Within
+// the session timeout it's possible to reestablish a connection to a different
+// server and keep the same session. This is means any ephemeral nodes and
+// watches are maintained.
+func Connect(servers []string, sessionTimeout time.Duration, options ...connOption) (*Conn, <-chan Event, error) {
+	if len(servers) == 0 {
+		return nil, nil, errors.New("zk: server list must not be empty")
+	}
+
+	srvs := make([]string, len(servers))
+
+	for i, addr := range servers {
+		if strings.Contains(addr, ":") {
+			srvs[i] = addr
+		} else {
+			srvs[i] = addr + ":" + strconv.Itoa(DefaultPort)
+		}
+	}
+
+	// Randomize the order of the servers to avoid creating hotspots
+	stringShuffle(srvs)
+
+	ec := make(chan Event, eventChanSize)
+	conn := &Conn{
+		dialer:         net.DialTimeout,
+		hostProvider:   &DNSHostProvider{},
+		conn:           nil,
+		state:          StateDisconnected,
+		eventChan:      ec,
+		shouldQuit:     make(chan struct{}),
+		connectTimeout: 1 * time.Second,
+		sendChan:       make(chan *request, sendChanSize),
+		requests:       make(map[int32]*request),
+		watchers:       make(map[watchPathType][]chan Event),
+		passwd:         emptyPassword,
+		logger:         DefaultLogger,
+
+		// Debug
+		reconnectDelay: 0,
+	}
+
+	// Set provided options.
+	for _, option := range options {
+		option(conn)
+	}
+
+	if err := conn.hostProvider.Init(srvs); err != nil {
+		return nil, nil, err
+	}
+
+	conn.setTimeouts(int32(sessionTimeout / time.Millisecond))
+
+	go func() {
+		conn.loop()
+		conn.flushRequests(ErrClosing)
+		conn.invalidateWatches(ErrClosing)
+		close(conn.eventChan)
+	}()
+	return conn, ec, nil
+}
+
+// WithDialer returns a connection option specifying a non-default Dialer.
+func WithDialer(dialer Dialer) connOption {
+	return func(c *Conn) {
+		c.dialer = dialer
+	}
+}
+
+// WithHostProvider returns a connection option specifying a non-default HostProvider.
+func WithHostProvider(hostProvider HostProvider) connOption {
+	return func(c *Conn) {
+		c.hostProvider = hostProvider
+	}
+}
+
+// WithLogger returns a connection option specifying a non-default logger <PR# #101>
+func WithLogger(logger Logger) connOption {
+	return func(c *Conn) {
+		c.logger = logger
+	}
+}
+
+// WithLogger returns a connection option specifying a non-default logger <PR# #101>
+func WithoutLogger() connOption {
+	return func(c *Conn) {
+		c.logger = NopLogger{log.New(os.Stderr, "", log.LstdFlags)}
+	}
+}
+
+func (c *Conn) Close() {
+	close(c.shouldQuit)
+
+	select {
+	case <-c.queueRequest(opClose, &closeRequest{}, &closeResponse{}, nil):
+	case <-time.After(time.Second):
+	}
+}
+
+// State returns the current state of the connection.
+func (c *Conn) State() State {
+	return State(atomic.LoadInt32((*int32)(&c.state)))
+}
+
+// SessionId returns the current session id of the connection.
+func (c *Conn) SessionID() int64 {
+	return atomic.LoadInt64(&c.sessionID)
+}
+
+// SetLogger sets the logger to be used for printing errors.
+// Logger is an interface provided by this package.
+func (c *Conn) SetLogger(l Logger) {
+	c.logger = l
+}
+
+func (c *Conn) setTimeouts(sessionTimeoutMs int32) {
+	c.sessionTimeoutMs = sessionTimeoutMs
+	sessionTimeout := time.Duration(sessionTimeoutMs) * time.Millisecond
+	c.recvTimeout = sessionTimeout * 2 / 3
+	c.pingInterval = c.recvTimeout / 2
+}
+
+func (c *Conn) setState(state State) {
+	atomic.StoreInt32((*int32)(&c.state), int32(state))
+	select {
+	case c.eventChan <- Event{Type: EventSession, State: state, Server: c.Server()}:
+	default:
+		// panic("zk: event channel full - it must be monitored and never allowed to be full")
+	}
+}
+
+func (c *Conn) connect() error {
+	var retryStart bool
+	for {
+		c.serverMu.Lock()
+		c.server, retryStart = c.hostProvider.Next()
+		c.serverMu.Unlock()
+		c.setState(StateConnecting)
+		if retryStart {
+			c.flushUnsentRequests(ErrNoServer)
+			select {
+			case <-time.After(time.Second):
+				// pass
+			case <-c.shouldQuit:
+				c.setState(StateDisconnected)
+				c.flushUnsentRequests(ErrClosing)
+				return ErrClosing
+			}
+		}
+
+		zkConn, err := c.dialer("tcp", c.Server(), c.connectTimeout)
+		if err == nil {
+			c.conn = zkConn
+			c.setState(StateConnected)
+			c.logger.Printf("Connected to %s", c.Server())
+			return nil
+		}
+
+		c.logger.Printf("Failed to connect to %s: %+v", c.Server(), err)
+	}
+}
+
+func (c *Conn) loop() {
+	for {
+		if err := c.connect(); err != nil {
+			// c.Close() was called
+			return
+		}
+
+		err := c.authenticate()
+		switch {
+		case err == ErrSessionExpired:
+			c.logger.Printf("Authentication failed: %s", err)
+			c.invalidateWatches(err)
+		case err != nil && c.conn != nil:
+			c.logger.Printf("Authentication failed: %s", err)
+			c.conn.Close()
+		case err == nil:
+			c.logger.Printf("Authenticated: id=%d, timeout=%d", c.SessionID(), c.sessionTimeoutMs)
+			c.hostProvider.Connected()       // mark success
+			closeChan := make(chan struct{}) // channel to tell send loop stop
+			var wg sync.WaitGroup
+
+			wg.Add(1)
+			go func() {
+				err := c.sendLoop(c.conn, closeChan)
+				c.logger.Printf("Send loop terminated: err=%v", err)
+				c.conn.Close() // causes recv loop to EOF/exit
+				wg.Done()
+			}()
+
+			wg.Add(1)
+			go func() {
+				err := c.recvLoop(c.conn)
+				c.logger.Printf("Recv loop terminated: err=%v", err)
+				if err == nil {
+					panic("zk: recvLoop should never return nil error")
+				}
+				close(closeChan) // tell send loop to exit
+				wg.Done()
+			}()
+
+			c.sendSetWatches()
+			wg.Wait()
+		}
+
+		c.setState(StateDisconnected)
+
+		select {
+		case <-c.shouldQuit:
+			c.flushRequests(ErrClosing)
+			return
+		default:
+		}
+
+		if err != ErrSessionExpired {
+			err = ErrConnectionClosed
+		}
+		c.flushRequests(err)
+
+		if c.reconnectDelay > 0 {
+			select {
+			case <-c.shouldQuit:
+				return
+			case <-time.After(c.reconnectDelay):
+			}
+		}
+	}
+}
+
+func (c *Conn) flushUnsentRequests(err error) {
+	for {
+		select {
+		default:
+			return
+		case req := <-c.sendChan:
+			req.recvChan <- response{-1, err}
+		}
+	}
+}
+
+// Send error to all pending requests and clear request map
+func (c *Conn) flushRequests(err error) {
+	c.requestsLock.Lock()
+	for _, req := range c.requests {
+		req.recvChan <- response{-1, err}
+	}
+	c.requests = make(map[int32]*request)
+	c.requestsLock.Unlock()
+}
+
+// Send error to all watchers and clear watchers map
+func (c *Conn) invalidateWatches(err error) {
+	c.watchersLock.Lock()
+	defer c.watchersLock.Unlock()
+
+	if len(c.watchers) >= 0 {
+		for pathType, watchers := range c.watchers {
+			ev := Event{Type: EventNotWatching, State: StateDisconnected, Path: pathType.path, Err: err}
+			for _, ch := range watchers {
+				ch <- ev
+				close(ch)
+			}
+		}
+		c.watchers = make(map[watchPathType][]chan Event)
+	}
+}
+
+func (c *Conn) sendSetWatches() {
+	c.watchersLock.Lock()
+	defer c.watchersLock.Unlock()
+
+	if len(c.watchers) == 0 {
+		return
+	}
+
+	req := &setWatchesRequest{
+		RelativeZxid: c.lastZxid,
+		DataWatches:  make([]string, 0),
+		ExistWatches: make([]string, 0),
+		ChildWatches: make([]string, 0),
+	}
+	n := 0
+	for pathType, watchers := range c.watchers {
+		if len(watchers) == 0 {
+			continue
+		}
+		switch pathType.wType {
+		case watchTypeData:
+			req.DataWatches = append(req.DataWatches, pathType.path)
+		case watchTypeExist:
+			req.ExistWatches = append(req.ExistWatches, pathType.path)
+		case watchTypeChild:
+			req.ChildWatches = append(req.ChildWatches, pathType.path)
+		}
+		n++
+	}
+	if n == 0 {
+		return
+	}
+
+	go func() {
+		res := &setWatchesResponse{}
+		_, err := c.request(opSetWatches, req, res, nil)
+		if err != nil {
+			c.logger.Printf("Failed to set previous watches: %s", err.Error())
+		}
+	}()
+}
+
+func (c *Conn) authenticate() error {
+	buf := make([]byte, 256)
+
+	// Encode and send a connect request.
+	n, err := encodePacket(buf[4:], &connectRequest{
+		ProtocolVersion: protocolVersion,
+		LastZxidSeen:    c.lastZxid,
+		TimeOut:         c.sessionTimeoutMs,
+		SessionID:       c.SessionID(),
+		Passwd:          c.passwd,
+	})
+	if err != nil {
+		return err
+	}
+
+	binary.BigEndian.PutUint32(buf[:4], uint32(n))
+
+	c.conn.SetWriteDeadline(time.Now().Add(c.recvTimeout * 10))
+	_, err = c.conn.Write(buf[:n+4])
+	c.conn.SetWriteDeadline(time.Time{})
+	if err != nil {
+		return err
+	}
+
+	// Receive and decode a connect response.
+	c.conn.SetReadDeadline(time.Now().Add(c.recvTimeout * 10))
+	_, err = io.ReadFull(c.conn, buf[:4])
+	c.conn.SetReadDeadline(time.Time{})
+	if err != nil {
+		return err
+	}
+
+	blen := int(binary.BigEndian.Uint32(buf[:4]))
+	if cap(buf) < blen {
+		buf = make([]byte, blen)
+	}
+
+	_, err = io.ReadFull(c.conn, buf[:blen])
+	if err != nil {
+		return err
+	}
+
+	r := connectResponse{}
+	_, err = decodePacket(buf[:blen], &r)
+	if err != nil {
+		return err
+	}
+	if r.SessionID == 0 {
+		atomic.StoreInt64(&c.sessionID, int64(0))
+		c.passwd = emptyPassword
+		c.lastZxid = 0
+		c.setState(StateExpired)
+		return ErrSessionExpired
+	}
+
+	atomic.StoreInt64(&c.sessionID, r.SessionID)
+	c.setTimeouts(r.TimeOut)
+	c.passwd = r.Passwd
+	c.setState(StateHasSession)
+
+	return nil
+}
+
+func (c *Conn) sendLoop(conn net.Conn, closeChan <-chan struct{}) error {
+	pingTicker := time.NewTicker(c.pingInterval)
+	defer pingTicker.Stop()
+
+	buf := make([]byte, bufferSize)
+	for {
+		select {
+		case req := <-c.sendChan:
+			header := &requestHeader{req.xid, req.opcode}
+			n, err := encodePacket(buf[4:], header)
+			if err != nil {
+				req.recvChan <- response{-1, err}
+				continue
+			}
+
+			n2, err := encodePacket(buf[4+n:], req.pkt)
+			if err != nil {
+				req.recvChan <- response{-1, err}
+				continue
+			}
+
+			n += n2
+
+			binary.BigEndian.PutUint32(buf[:4], uint32(n))
+
+			c.requestsLock.Lock()
+			select {
+			case <-closeChan:
+				req.recvChan <- response{-1, ErrConnectionClosed}
+				c.requestsLock.Unlock()
+				return ErrConnectionClosed
+			default:
+			}
+			c.requests[req.xid] = req
+			c.requestsLock.Unlock()
+
+			conn.SetWriteDeadline(time.Now().Add(c.recvTimeout))
+			_, err = conn.Write(buf[:n+4])
+			conn.SetWriteDeadline(time.Time{})
+			if err != nil {
+				req.recvChan <- response{-1, err}
+				conn.Close()
+				return err
+			}
+		case <-pingTicker.C:
+			n, err := encodePacket(buf[4:], &requestHeader{Xid: -2, Opcode: opPing})
+			if err != nil {
+				panic("zk: opPing should never fail to serialize")
+			}
+
+			binary.BigEndian.PutUint32(buf[:4], uint32(n))
+
+			conn.SetWriteDeadline(time.Now().Add(c.recvTimeout))
+			_, err = conn.Write(buf[:n+4])
+			conn.SetWriteDeadline(time.Time{})
+			if err != nil {
+				conn.Close()
+				return err
+			}
+		case <-closeChan:
+			return nil
+		}
+	}
+}
+
+func (c *Conn) recvLoop(conn net.Conn) error {
+	buf := make([]byte, bufferSize)
+	for {
+		// package length
+		conn.SetReadDeadline(time.Now().Add(c.recvTimeout))
+		_, err := io.ReadFull(conn, buf[:4])
+		if err != nil {
+			return err
+		}
+
+		blen := int(binary.BigEndian.Uint32(buf[:4]))
+		if cap(buf) < blen {
+			buf = make([]byte, blen)
+		}
+
+		_, err = io.ReadFull(conn, buf[:blen])
+		conn.SetReadDeadline(time.Time{})
+		if err != nil {
+			return err
+		}
+
+		res := responseHeader{}
+		_, err = decodePacket(buf[:16], &res)
+		if err != nil {
+			return err
+		}
+
+		if res.Xid == -1 {
+			res := &watcherEvent{}
+			_, err := decodePacket(buf[16:blen], res)
+			if err != nil {
+				return err
+			}
+			ev := Event{
+				Type:  res.Type,
+				State: res.State,
+				Path:  res.Path,
+				Err:   nil,
+			}
+			select {
+			case c.eventChan <- ev:
+			default:
+			}
+			wTypes := make([]watchType, 0, 2)
+			switch res.Type {
+			case EventNodeCreated:
+				wTypes = append(wTypes, watchTypeExist)
+			case EventNodeDeleted, EventNodeDataChanged:
+				wTypes = append(wTypes, watchTypeExist, watchTypeData, watchTypeChild)
+			case EventNodeChildrenChanged:
+				wTypes = append(wTypes, watchTypeChild)
+			}
+			c.watchersLock.Lock()
+			for _, t := range wTypes {
+				wpt := watchPathType{res.Path, t}
+				if watchers := c.watchers[wpt]; watchers != nil && len(watchers) > 0 {
+					for _, ch := range watchers {
+						ch <- ev
+						close(ch)
+					}
+					delete(c.watchers, wpt)
+				}
+			}
+			c.watchersLock.Unlock()
+		} else if res.Xid == -2 {
+			// Ping response. Ignore.
+		} else if res.Xid < 0 {
+			c.logger.Printf("Xid < 0 (%d) but not ping or watcher event", res.Xid)
+		} else {
+			if res.Zxid > 0 {
+				c.lastZxid = res.Zxid
+			}
+
+			c.requestsLock.Lock()
+			req, ok := c.requests[res.Xid]
+			if ok {
+				delete(c.requests, res.Xid)
+			}
+			c.requestsLock.Unlock()
+
+			if !ok {
+				c.logger.Printf("Response for unknown request with xid %d", res.Xid)
+			} else {
+				if res.Err != 0 {
+					err = res.Err.toError()
+				} else {
+					_, err = decodePacket(buf[16:blen], req.recvStruct)
+				}
+				if req.recvFunc != nil {
+					req.recvFunc(req, &res, err)
+				}
+				req.recvChan <- response{res.Zxid, err}
+				if req.opcode == opClose {
+					return io.EOF
+				}
+			}
+		}
+	}
+}
+
+func (c *Conn) nextXid() int32 {
+	return int32(atomic.AddUint32(&c.xid, 1) & 0x7fffffff)
+}
+
+func (c *Conn) addWatcher(path string, watchType watchType) <-chan Event {
+	c.watchersLock.Lock()
+	defer c.watchersLock.Unlock()
+
+	ch := make(chan Event, 1)
+	wpt := watchPathType{path, watchType}
+	c.watchers[wpt] = append(c.watchers[wpt], ch)
+	return ch
+}
+
+func (c *Conn) queueRequest(opcode int32, req interface{}, res interface{}, recvFunc func(*request, *responseHeader, error)) <-chan response {
+	rq := &request{
+		xid:        c.nextXid(),
+		opcode:     opcode,
+		pkt:        req,
+		recvStruct: res,
+		recvChan:   make(chan response, 1),
+		recvFunc:   recvFunc,
+	}
+	c.sendChan <- rq
+	return rq.recvChan
+}
+
+func (c *Conn) request(opcode int32, req interface{}, res interface{}, recvFunc func(*request, *responseHeader, error)) (int64, error) {
+	r := <-c.queueRequest(opcode, req, res, recvFunc)
+	return r.zxid, r.err
+}
+
+func (c *Conn) AddAuth(scheme string, auth []byte) error {
+	_, err := c.request(opSetAuth, &setAuthRequest{Type: 0, Scheme: scheme, Auth: auth}, &setAuthResponse{}, nil)
+	return err
+}
+
+func (c *Conn) Children(path string) ([]string, *Stat, error) {
+	res := &getChildren2Response{}
+	_, err := c.request(opGetChildren2, &getChildren2Request{Path: path, Watch: false}, res, nil)
+	return res.Children, &res.Stat, err
+}
+
+func (c *Conn) ChildrenW(path string) ([]string, *Stat, <-chan Event, error) {
+	var ech <-chan Event
+	res := &getChildren2Response{}
+	_, err := c.request(opGetChildren2, &getChildren2Request{Path: path, Watch: true}, res, func(req *request, res *responseHeader, err error) {
+		if err == nil {
+			ech = c.addWatcher(path, watchTypeChild)
+		}
+	})
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	return res.Children, &res.Stat, ech, err
+}
+
+func (c *Conn) Get(path string) ([]byte, *Stat, error) {
+	res := &getDataResponse{}
+	_, err := c.request(opGetData, &getDataRequest{Path: path, Watch: false}, res, nil)
+	return res.Data, &res.Stat, err
+}
+
+// GetW returns the contents of a znode and sets a watch
+func (c *Conn) GetW(path string) ([]byte, *Stat, <-chan Event, error) {
+	var ech <-chan Event
+	res := &getDataResponse{}
+	_, err := c.request(opGetData, &getDataRequest{Path: path, Watch: true}, res, func(req *request, res *responseHeader, err error) {
+		if err == nil {
+			ech = c.addWatcher(path, watchTypeData)
+		}
+	})
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	return res.Data, &res.Stat, ech, err
+}
+
+func (c *Conn) Set(path string, data []byte, version int32) (*Stat, error) {
+	if path == "" {
+		return nil, ErrInvalidPath
+	}
+	res := &setDataResponse{}
+	_, err := c.request(opSetData, &SetDataRequest{path, data, version}, res, nil)
+	return &res.Stat, err
+}
+
+func (c *Conn) Create(path string, data []byte, flags int32, acl []ACL) (string, error) {
+	res := &createResponse{}
+	_, err := c.request(opCreate, &CreateRequest{path, data, acl, flags}, res, nil)
+	return res.Path, err
+}
+
+// CreateProtectedEphemeralSequential fixes a race condition if the server crashes
+// after it creates the node. On reconnect the session may still be valid so the
+// ephemeral node still exists. Therefore, on reconnect we need to check if a node
+// with a GUID generated on create exists.
+func (c *Conn) CreateProtectedEphemeralSequential(path string, data []byte, acl []ACL) (string, error) {
+	var guid [16]byte
+	_, err := io.ReadFull(rand.Reader, guid[:16])
+	if err != nil {
+		return "", err
+	}
+	guidStr := fmt.Sprintf("%x", guid)
+
+	parts := strings.Split(path, "/")
+	parts[len(parts)-1] = fmt.Sprintf("%s%s-%s", protectedPrefix, guidStr, parts[len(parts)-1])
+	rootPath := strings.Join(parts[:len(parts)-1], "/")
+	protectedPath := strings.Join(parts, "/")
+
+	var newPath string
+	for i := 0; i < 3; i++ {
+		newPath, err = c.Create(protectedPath, data, FlagEphemeral|FlagSequence, acl)
+		switch err {
+		case ErrSessionExpired:
+			// No need to search for the node since it can't exist. Just try again.
+		case ErrConnectionClosed:
+			children, _, err := c.Children(rootPath)
+			if err != nil {
+				return "", err
+			}
+			for _, p := range children {
+				parts := strings.Split(p, "/")
+				if pth := parts[len(parts)-1]; strings.HasPrefix(pth, protectedPrefix) {
+					if g := pth[len(protectedPrefix) : len(protectedPrefix)+32]; g == guidStr {
+						return rootPath + "/" + p, nil
+					}
+				}
+			}
+		case nil:
+			return newPath, nil
+		default:
+			return "", err
+		}
+	}
+	return "", err
+}
+
+func (c *Conn) Delete(path string, version int32) error {
+	_, err := c.request(opDelete, &DeleteRequest{path, version}, &deleteResponse{}, nil)
+	return err
+}
+
+func (c *Conn) Exists(path string) (bool, *Stat, error) {
+	res := &existsResponse{}
+	_, err := c.request(opExists, &existsRequest{Path: path, Watch: false}, res, nil)
+	exists := true
+	if err == ErrNoNode {
+		exists = false
+		err = nil
+	}
+	return exists, &res.Stat, err
+}
+
+func (c *Conn) ExistsW(path string) (bool, *Stat, <-chan Event, error) {
+	var ech <-chan Event
+	res := &existsResponse{}
+	_, err := c.request(opExists, &existsRequest{Path: path, Watch: true}, res, func(req *request, res *responseHeader, err error) {
+		if err == nil {
+			ech = c.addWatcher(path, watchTypeData)
+		} else if err == ErrNoNode {
+			ech = c.addWatcher(path, watchTypeExist)
+		}
+	})
+	exists := true
+	if err == ErrNoNode {
+		exists = false
+		err = nil
+	}
+	if err != nil {
+		return false, nil, nil, err
+	}
+	return exists, &res.Stat, ech, err
+}
+
+func (c *Conn) GetACL(path string) ([]ACL, *Stat, error) {
+	res := &getAclResponse{}
+	_, err := c.request(opGetAcl, &getAclRequest{Path: path}, res, nil)
+	return res.Acl, &res.Stat, err
+}
+func (c *Conn) SetACL(path string, acl []ACL, version int32) (*Stat, error) {
+	res := &setAclResponse{}
+	_, err := c.request(opSetAcl, &setAclRequest{Path: path, Acl: acl, Version: version}, res, nil)
+	return &res.Stat, err
+}
+
+func (c *Conn) Sync(path string) (string, error) {
+	res := &syncResponse{}
+	_, err := c.request(opSync, &syncRequest{Path: path}, res, nil)
+	return res.Path, err
+}
+
+type MultiResponse struct {
+	Stat   *Stat
+	String string
+}
+
+// Multi executes multiple ZooKeeper operations or none of them. The provided
+// ops must be one of *CreateRequest, *DeleteRequest, *SetDataRequest, or
+// *CheckVersionRequest.
+func (c *Conn) Multi(ops ...interface{}) ([]MultiResponse, error) {
+	req := &multiRequest{
+		Ops:        make([]multiRequestOp, 0, len(ops)),
+		DoneHeader: multiHeader{Type: -1, Done: true, Err: -1},
+	}
+	for _, op := range ops {
+		var opCode int32
+		switch op.(type) {
+		case *CreateRequest:
+			opCode = opCreate
+		case *SetDataRequest:
+			opCode = opSetData
+		case *DeleteRequest:
+			opCode = opDelete
+		case *CheckVersionRequest:
+			opCode = opCheck
+		default:
+			return nil, fmt.Errorf("unknown operation type %T", op)
+		}
+		req.Ops = append(req.Ops, multiRequestOp{multiHeader{opCode, false, -1}, op})
+	}
+	res := &multiResponse{}
+	_, err := c.request(opMulti, req, res, nil)
+	mr := make([]MultiResponse, len(res.Ops))
+	for i, op := range res.Ops {
+		mr[i] = MultiResponse{Stat: op.Stat, String: op.String}
+	}
+	return mr, err
+}
+
+// Server returns the current or last-connected server name.
+func (c *Conn) Server() string {
+	c.serverMu.Lock()
+	defer c.serverMu.Unlock()
+	return c.server
+}

vendor/github.com/samuel/go-zookeeper/zk/constants.go

@@ -0,0 +1,240 @@
+package zk
+
+import (
+	"errors"
+)
+
+const (
+	protocolVersion = 0
+
+	DefaultPort = 2181
+)
+
+const (
+	opNotify       = 0
+	opCreate       = 1
+	opDelete       = 2
+	opExists       = 3
+	opGetData      = 4
+	opSetData      = 5
+	opGetAcl       = 6
+	opSetAcl       = 7
+	opGetChildren  = 8
+	opSync         = 9
+	opPing         = 11
+	opGetChildren2 = 12
+	opCheck        = 13
+	opMulti        = 14
+	opClose        = -11
+	opSetAuth      = 100
+	opSetWatches   = 101
+	// Not in protocol, used internally
+	opWatcherEvent = -2
+)
+
+const (
+	EventNodeCreated         = EventType(1)
+	EventNodeDeleted         = EventType(2)
+	EventNodeDataChanged     = EventType(3)
+	EventNodeChildrenChanged = EventType(4)
+
+	EventSession     = EventType(-1)
+	EventNotWatching = EventType(-2)
+)
+
+var (
+	eventNames = map[EventType]string{
+		EventNodeCreated:         "EventNodeCreated",
+		EventNodeDeleted:         "EventNodeDeleted",
+		EventNodeDataChanged:     "EventNodeDataChanged",
+		EventNodeChildrenChanged: "EventNodeChildrenChanged",
+		EventSession:             "EventSession",
+		EventNotWatching:         "EventNotWatching",
+	}
+)
+
+const (
+	StateUnknown           = State(-1)
+	StateDisconnected      = State(0)
+	StateConnecting        = State(1)
+	StateAuthFailed        = State(4)
+	StateConnectedReadOnly = State(5)
+	StateSaslAuthenticated = State(6)
+	StateExpired           = State(-112)
+	// StateAuthFailed        = State(-113)
+
+	StateConnected  = State(100)
+	StateHasSession = State(101)
+)
+
+const (
+	FlagEphemeral = 1
+	FlagSequence  = 2
+)
+
+var (
+	stateNames = map[State]string{
+		StateUnknown:           "StateUnknown",
+		StateDisconnected:      "StateDisconnected",
+		StateConnectedReadOnly: "StateConnectedReadOnly",
+		StateSaslAuthenticated: "StateSaslAuthenticated",
+		StateExpired:           "StateExpired",
+		StateAuthFailed:        "StateAuthFailed",
+		StateConnecting:        "StateConnecting",
+		StateConnected:         "StateConnected",
+		StateHasSession:        "StateHasSession",
+	}
+)
+
+type State int32
+
+func (s State) String() string {
+	if name := stateNames[s]; name != "" {
+		return name
+	}
+	return "Unknown"
+}
+
+type ErrCode int32
+
+var (
+	ErrConnectionClosed        = errors.New("zk: connection closed")
+	ErrUnknown                 = errors.New("zk: unknown error")
+	ErrAPIError                = errors.New("zk: api error")
+	ErrNoNode                  = errors.New("zk: node does not exist")
+	ErrNoAuth                  = errors.New("zk: not authenticated")
+	ErrBadVersion              = errors.New("zk: version conflict")
+	ErrNoChildrenForEphemerals = errors.New("zk: ephemeral nodes may not have children")
+	ErrNodeExists              = errors.New("zk: node already exists")
+	ErrNotEmpty                = errors.New("zk: node has children")
+	ErrSessionExpired          = errors.New("zk: session has been expired by the server")
+	ErrInvalidACL              = errors.New("zk: invalid ACL specified")
+	ErrAuthFailed              = errors.New("zk: client authentication failed")
+	ErrClosing                 = errors.New("zk: zookeeper is closing")
+	ErrNothing                 = errors.New("zk: no server responsees to process")
+	ErrSessionMoved            = errors.New("zk: session moved to another server, so operation is ignored")
+
+	// ErrInvalidCallback         = errors.New("zk: invalid callback specified")
+	errCodeToError = map[ErrCode]error{
+		0:                          nil,
+		errAPIError:                ErrAPIError,
+		errNoNode:                  ErrNoNode,
+		errNoAuth:                  ErrNoAuth,
+		errBadVersion:              ErrBadVersion,
+		errNoChildrenForEphemerals: ErrNoChildrenForEphemerals,
+		errNodeExists:              ErrNodeExists,
+		errNotEmpty:                ErrNotEmpty,
+		errSessionExpired:          ErrSessionExpired,
+		// errInvalidCallback:         ErrInvalidCallback,
+		errInvalidAcl:   ErrInvalidACL,
+		errAuthFailed:   ErrAuthFailed,
+		errClosing:      ErrClosing,
+		errNothing:      ErrNothing,
+		errSessionMoved: ErrSessionMoved,
+	}
+)
+
+func (e ErrCode) toError() error {
+	if err, ok := errCodeToError[e]; ok {
+		return err
+	}
+	return ErrUnknown
+}
+
+const (
+	errOk = 0
+	// System and server-side errors
+	errSystemError          = -1
+	errRuntimeInconsistency = -2
+	errDataInconsistency    = -3
+	errConnectionLoss       = -4
+	errMarshallingError     = -5
+	errUnimplemented        = -6
+	errOperationTimeout     = -7
+	errBadArguments         = -8
+	errInvalidState         = -9
+	// API errors
+	errAPIError                = ErrCode(-100)
+	errNoNode                  = ErrCode(-101) // *
+	errNoAuth                  = ErrCode(-102)
+	errBadVersion              = ErrCode(-103) // *
+	errNoChildrenForEphemerals = ErrCode(-108)
+	errNodeExists              = ErrCode(-110) // *
+	errNotEmpty                = ErrCode(-111)
+	errSessionExpired          = ErrCode(-112)
+	errInvalidCallback         = ErrCode(-113)
+	errInvalidAcl              = ErrCode(-114)
+	errAuthFailed              = ErrCode(-115)
+	errClosing                 = ErrCode(-116)
+	errNothing                 = ErrCode(-117)
+	errSessionMoved            = ErrCode(-118)
+)
+
+// Constants for ACL permissions
+const (
+	PermRead = 1 << iota
+	PermWrite
+	PermCreate
+	PermDelete
+	PermAdmin
+	PermAll = 0x1f
+)
+
+var (
+	emptyPassword = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+	opNames       = map[int32]string{
+		opNotify:       "notify",
+		opCreate:       "create",
+		opDelete:       "delete",
+		opExists:       "exists",
+		opGetData:      "getData",
+		opSetData:      "setData",
+		opGetAcl:       "getACL",
+		opSetAcl:       "setACL",
+		opGetChildren:  "getChildren",
+		opSync:         "sync",
+		opPing:         "ping",
+		opGetChildren2: "getChildren2",
+		opCheck:        "check",
+		opMulti:        "multi",
+		opClose:        "close",
+		opSetAuth:      "setAuth",
+		opSetWatches:   "setWatches",
+
+		opWatcherEvent: "watcherEvent",
+	}
+)
+
+type EventType int32
+
+func (t EventType) String() string {
+	if name := eventNames[t]; name != "" {
+		return name
+	}
+	return "Unknown"
+}
+
+// Mode is used to build custom server modes (leader|follower|standalone).
+type Mode uint8
+
+func (m Mode) String() string {
+	if name := modeNames[m]; name != "" {
+		return name
+	}
+	return "unknown"
+}
+
+const (
+	ModeUnknown    Mode = iota
+	ModeLeader     Mode = iota
+	ModeFollower   Mode = iota
+	ModeStandalone Mode = iota
+)
+
+var (
+	modeNames = map[Mode]string{
+		ModeLeader:     "leader",
+		ModeFollower:   "follower",
+		ModeStandalone: "standalone",
+	}
+)

vendor/github.com/samuel/go-zookeeper/zk/dnshostprovider.go

@@ -0,0 +1,88 @@
+package zk
+
+import (
+	"fmt"
+	"net"
+	"sync"
+)
+
+// DNSHostProvider is the default HostProvider. It currently matches
+// the Java StaticHostProvider, resolving hosts from DNS once during
+// the call to Init.  It could be easily extended to re-query DNS
+// periodically or if there is trouble connecting.
+type DNSHostProvider struct {
+	mu         sync.Mutex // Protects everything, so we can add asynchronous updates later.
+	servers    []string
+	curr       int
+	last       int
+	lookupHost func(string) ([]string, error) // Override of net.LookupHost, for testing.
+}
+
+// Init is called first, with the servers specified in the connection
+// string. It uses DNS to look up addresses for each server, then
+// shuffles them all together.
+func (hp *DNSHostProvider) Init(servers []string) error {
+	hp.mu.Lock()
+	defer hp.mu.Unlock()
+
+	lookupHost := hp.lookupHost
+	if lookupHost == nil {
+		lookupHost = net.LookupHost
+	}
+
+	found := []string{}
+	for _, server := range servers {
+		host, port, err := net.SplitHostPort(server)
+		if err != nil {
+			return err
+		}
+		addrs, err := lookupHost(host)
+		if err != nil {
+			return err
+		}
+		for _, addr := range addrs {
+			found = append(found, net.JoinHostPort(addr, port))
+		}
+	}
+
+	if len(found) == 0 {
+		return fmt.Errorf("No hosts found for addresses %q", servers)
+	}
+
+	// Randomize the order of the servers to avoid creating hotspots
+	stringShuffle(found)
+
+	hp.servers = found
+	hp.curr = -1
+	hp.last = -1
+
+	return nil
+}
+
+// Len returns the number of servers available
+func (hp *DNSHostProvider) Len() int {
+	hp.mu.Lock()
+	defer hp.mu.Unlock()
+	return len(hp.servers)
+}
+
+// Next returns the next server to connect to. retryStart will be true
+// if we've looped through all known servers without Connected() being
+// called.
+func (hp *DNSHostProvider) Next() (server string, retryStart bool) {
+	hp.mu.Lock()
+	defer hp.mu.Unlock()
+	hp.curr = (hp.curr + 1) % len(hp.servers)
+	retryStart = hp.curr == hp.last
+	if hp.last == -1 {
+		hp.last = 0
+	}
+	return hp.servers[hp.curr], retryStart
+}
+
+// Connected notifies the HostProvider of a successful connection.
+func (hp *DNSHostProvider) Connected() {
+	hp.mu.Lock()
+	defer hp.mu.Unlock()
+	hp.last = hp.curr
+}

vendor/github.com/samuel/go-zookeeper/zk/flw.go

@@ -0,0 +1,266 @@
+package zk
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// FLWSrvr is a FourLetterWord helper function. In particular, this function pulls the srvr output
+// from the zookeeper instances and parses the output. A slice of *ServerStats structs are returned
+// as well as a boolean value to indicate whether this function processed successfully.
+//
+// If the boolean value is false there was a problem. If the *ServerStats slice is empty or nil,
+// then the error happened before we started to obtain 'srvr' values. Otherwise, one of the
+// servers had an issue and the "Error" value in the struct should be inspected to determine
+// which server had the issue.
+func FLWSrvr(servers []string, timeout time.Duration) ([]*ServerStats, bool) {
+	// different parts of the regular expression that are required to parse the srvr output
+	const (
+		zrVer   = `^Zookeeper version: ([A-Za-z0-9\.\-]+), built on (\d\d/\d\d/\d\d\d\d \d\d:\d\d [A-Za-z0-9:\+\-]+)`
+		zrLat   = `^Latency min/avg/max: (\d+)/(\d+)/(\d+)`
+		zrNet   = `^Received: (\d+).*\n^Sent: (\d+).*\n^Connections: (\d+).*\n^Outstanding: (\d+)`
+		zrState = `^Zxid: (0x[A-Za-z0-9]+).*\n^Mode: (\w+).*\n^Node count: (\d+)`
+	)
+
+	// build the regex from the pieces above
+	re, err := regexp.Compile(fmt.Sprintf(`(?m:\A%v.*\n%v.*\n%v.*\n%v)`, zrVer, zrLat, zrNet, zrState))
+	if err != nil {
+		return nil, false
+	}
+
+	imOk := true
+	servers = FormatServers(servers)
+	ss := make([]*ServerStats, len(servers))
+
+	for i := range ss {
+		response, err := fourLetterWord(servers[i], "srvr", timeout)
+
+		if err != nil {
+			ss[i] = &ServerStats{Error: err}
+			imOk = false
+			continue
+		}
+
+		matches := re.FindAllStringSubmatch(string(response), -1)
+
+		if matches == nil {
+			err := fmt.Errorf("unable to parse fields from zookeeper response (no regex matches)")
+			ss[i] = &ServerStats{Error: err}
+			imOk = false
+			continue
+		}
+
+		match := matches[0][1:]
+
+		// determine current server
+		var srvrMode Mode
+		switch match[10] {
+		case "leader":
+			srvrMode = ModeLeader
+		case "follower":
+			srvrMode = ModeFollower
+		case "standalone":
+			srvrMode = ModeStandalone
+		default:
+			srvrMode = ModeUnknown
+		}
+
+		buildTime, err := time.Parse("01/02/2006 15:04 MST", match[1])
+
+		if err != nil {
+			ss[i] = &ServerStats{Error: err}
+			imOk = false
+			continue
+		}
+
+		parsedInt, err := strconv.ParseInt(match[9], 0, 64)
+
+		if err != nil {
+			ss[i] = &ServerStats{Error: err}
+			imOk = false
+			continue
+		}
+
+		// the ZxID value is an int64 with two int32s packed inside
+		// the high int32 is the epoch (i.e., number of leader elections)
+		// the low int32 is the counter
+		epoch := int32(parsedInt >> 32)
+		counter := int32(parsedInt & 0xFFFFFFFF)
+
+		// within the regex above, these values must be numerical
+		// so we can avoid useless checking of the error return value
+		minLatency, _ := strconv.ParseInt(match[2], 0, 64)
+		avgLatency, _ := strconv.ParseInt(match[3], 0, 64)
+		maxLatency, _ := strconv.ParseInt(match[4], 0, 64)
+		recv, _ := strconv.ParseInt(match[5], 0, 64)
+		sent, _ := strconv.ParseInt(match[6], 0, 64)
+		cons, _ := strconv.ParseInt(match[7], 0, 64)
+		outs, _ := strconv.ParseInt(match[8], 0, 64)
+		ncnt, _ := strconv.ParseInt(match[11], 0, 64)
+
+		ss[i] = &ServerStats{
+			Sent:        sent,
+			Received:    recv,
+			NodeCount:   ncnt,
+			MinLatency:  minLatency,
+			AvgLatency:  avgLatency,
+			MaxLatency:  maxLatency,
+			Connections: cons,
+			Outstanding: outs,
+			Epoch:       epoch,
+			Counter:     counter,
+			BuildTime:   buildTime,
+			Mode:        srvrMode,
+			Version:     match[0],
+		}
+	}
+
+	return ss, imOk
+}
+
+// FLWRuok is a FourLetterWord helper function. In particular, this function
+// pulls the ruok output from each server.
+func FLWRuok(servers []string, timeout time.Duration) []bool {
+	servers = FormatServers(servers)
+	oks := make([]bool, len(servers))
+
+	for i := range oks {
+		response, err := fourLetterWord(servers[i], "ruok", timeout)
+
+		if err != nil {
+			continue
+		}
+
+		if bytes.Equal(response[:4], []byte("imok")) {
+			oks[i] = true
+		}
+	}
+	return oks
+}
+
+// FLWCons is a FourLetterWord helper function. In particular, this function
+// pulls the ruok output from each server.
+//
+// As with FLWSrvr, the boolean value indicates whether one of the requests had
+// an issue. The Clients struct has an Error value that can be checked.
+func FLWCons(servers []string, timeout time.Duration) ([]*ServerClients, bool) {
+	const (
+		zrAddr = `^ /((?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?):(?:\d+))\[\d+\]`
+		zrPac  = `\(queued=(\d+),recved=(\d+),sent=(\d+),sid=(0x[A-Za-z0-9]+),lop=(\w+),est=(\d+),to=(\d+),`
+		zrSesh = `lcxid=(0x[A-Za-z0-9]+),lzxid=(0x[A-Za-z0-9]+),lresp=(\d+),llat=(\d+),minlat=(\d+),avglat=(\d+),maxlat=(\d+)\)`
+	)
+
+	re, err := regexp.Compile(fmt.Sprintf("%v%v%v", zrAddr, zrPac, zrSesh))
+	if err != nil {
+		return nil, false
+	}
+
+	servers = FormatServers(servers)
+	sc := make([]*ServerClients, len(servers))
+	imOk := true
+
+	for i := range sc {
+		response, err := fourLetterWord(servers[i], "cons", timeout)
+
+		if err != nil {
+			sc[i] = &ServerClients{Error: err}
+			imOk = false
+			continue
+		}
+
+		scan := bufio.NewScanner(bytes.NewReader(response))
+
+		var clients []*ServerClient
+
+		for scan.Scan() {
+			line := scan.Bytes()
+
+			if len(line) == 0 {
+				continue
+			}
+
+			m := re.FindAllStringSubmatch(string(line), -1)
+
+			if m == nil {
+				err := fmt.Errorf("unable to parse fields from zookeeper response (no regex matches)")
+				sc[i] = &ServerClients{Error: err}
+				imOk = false
+				continue
+			}
+
+			match := m[0][1:]
+
+			queued, _ := strconv.ParseInt(match[1], 0, 64)
+			recvd, _ := strconv.ParseInt(match[2], 0, 64)
+			sent, _ := strconv.ParseInt(match[3], 0, 64)
+			sid, _ := strconv.ParseInt(match[4], 0, 64)
+			est, _ := strconv.ParseInt(match[6], 0, 64)
+			timeout, _ := strconv.ParseInt(match[7], 0, 32)
+			lcxid, _ := parseInt64(match[8])
+			lzxid, _ := parseInt64(match[9])
+			lresp, _ := strconv.ParseInt(match[10], 0, 64)
+			llat, _ := strconv.ParseInt(match[11], 0, 32)
+			minlat, _ := strconv.ParseInt(match[12], 0, 32)
+			avglat, _ := strconv.ParseInt(match[13], 0, 32)
+			maxlat, _ := strconv.ParseInt(match[14], 0, 32)
+
+			clients = append(clients, &ServerClient{
+				Queued:        queued,
+				Received:      recvd,
+				Sent:          sent,
+				SessionID:     sid,
+				Lcxid:         int64(lcxid),
+				Lzxid:         int64(lzxid),
+				Timeout:       int32(timeout),
+				LastLatency:   int32(llat),
+				MinLatency:    int32(minlat),
+				AvgLatency:    int32(avglat),
+				MaxLatency:    int32(maxlat),
+				Established:   time.Unix(est, 0),
+				LastResponse:  time.Unix(lresp, 0),
+				Addr:          match[0],
+				LastOperation: match[5],
+			})
+		}
+
+		sc[i] = &ServerClients{Clients: clients}
+	}
+
+	return sc, imOk
+}
+
+// parseInt64 is similar to strconv.ParseInt, but it also handles hex values that represent negative numbers
+func parseInt64(s string) (int64, error) {
+	if strings.HasPrefix(s, "0x") {
+		i, err := strconv.ParseUint(s, 0, 64)
+		return int64(i), err
+	}
+	return strconv.ParseInt(s, 0, 64)
+}
+
+func fourLetterWord(server, command string, timeout time.Duration) ([]byte, error) {
+	conn, err := net.DialTimeout("tcp", server, timeout)
+	if err != nil {
+		return nil, err
+	}
+
+	// the zookeeper server should automatically close this socket
+	// once the command has been processed, but better safe than sorry
+	defer conn.Close()
+
+	conn.SetWriteDeadline(time.Now().Add(timeout))
+	_, err = conn.Write([]byte(command))
+	if err != nil {
+		return nil, err
+	}
+
+	conn.SetReadDeadline(time.Now().Add(timeout))
+	return ioutil.ReadAll(conn)
+}

vendor/github.com/samuel/go-zookeeper/zk/lock.go

@@ -0,0 +1,142 @@
+package zk
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+var (
+	// ErrDeadlock is returned by Lock when trying to lock twice without unlocking first
+	ErrDeadlock = errors.New("zk: trying to acquire a lock twice")
+	// ErrNotLocked is returned by Unlock when trying to release a lock that has not first be acquired.
+	ErrNotLocked = errors.New("zk: not locked")
+)
+
+// Lock is a mutual exclusion lock.
+type Lock struct {
+	c        *Conn
+	path     string
+	acl      []ACL
+	lockPath string
+	seq      int
+}
+
+// NewLock creates a new lock instance using the provided connection, path, and acl.
+// The path must be a node that is only used by this lock. A lock instances starts
+// unlocked until Lock() is called.
+func NewLock(c *Conn, path string, acl []ACL) *Lock {
+	return &Lock{
+		c:    c,
+		path: path,
+		acl:  acl,
+	}
+}
+
+func parseSeq(path string) (int, error) {
+	parts := strings.Split(path, "-")
+	return strconv.Atoi(parts[len(parts)-1])
+}
+
+// Lock attempts to acquire the lock. It will wait to return until the lock
+// is acquired or an error occurs. If this instance already has the lock
+// then ErrDeadlock is returned.
+func (l *Lock) Lock() error {
+	if l.lockPath != "" {
+		return ErrDeadlock
+	}
+
+	prefix := fmt.Sprintf("%s/lock-", l.path)
+
+	path := ""
+	var err error
+	for i := 0; i < 3; i++ {
+		path, err = l.c.CreateProtectedEphemeralSequential(prefix, []byte{}, l.acl)
+		if err == ErrNoNode {
+			// Create parent node.
+			parts := strings.Split(l.path, "/")
+			pth := ""
+			for _, p := range parts[1:] {
+				pth += "/" + p
+				_, err := l.c.Create(pth, []byte{}, 0, l.acl)
+				if err != nil && err != ErrNodeExists {
+					return err
+				}
+			}
+		} else if err == nil {
+			break
+		} else {
+			return err
+		}
+	}
+	if err != nil {
+		return err
+	}
+
+	seq, err := parseSeq(path)
+	if err != nil {
+		return err
+	}
+
+	for {
+		children, _, err := l.c.Children(l.path)
+		if err != nil {
+			return err
+		}
+
+		lowestSeq := seq
+		prevSeq := 0
+		prevSeqPath := ""
+		for _, p := range children {
+			s, err := parseSeq(p)
+			if err != nil {
+				return err
+			}
+			if s < lowestSeq {
+				lowestSeq = s
+			}
+			if s < seq && s > prevSeq {
+				prevSeq = s
+				prevSeqPath = p
+			}
+		}
+
+		if seq == lowestSeq {
+			// Acquired the lock
+			break
+		}
+
+		// Wait on the node next in line for the lock
+		_, _, ch, err := l.c.GetW(l.path + "/" + prevSeqPath)
+		if err != nil && err != ErrNoNode {
+			return err
+		} else if err != nil && err == ErrNoNode {
+			// try again
+			continue
+		}
+
+		ev := <-ch
+		if ev.Err != nil {
+			return ev.Err
+		}
+	}
+
+	l.seq = seq
+	l.lockPath = path
+	return nil
+}
+
+// Unlock releases an acquired lock. If the lock is not currently acquired by
+// this Lock instance than ErrNotLocked is returned.
+func (l *Lock) Unlock() error {
+	if l.lockPath == "" {
+		return ErrNotLocked
+	}
+	if err := l.c.Delete(l.lockPath, -1); err != nil {
+		return err
+	}
+	l.lockPath = ""
+	l.seq = 0
+	return nil
+}

vendor/github.com/samuel/go-zookeeper/zk/server_help.go

@@ -0,0 +1,190 @@
+package zk
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"math/rand"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
+type TestServer struct {
+	Port int
+	Path string
+	Srv  *Server
+}
+
+type TestCluster struct {
+	Path    string
+	Servers []TestServer
+}
+
+func StartTestCluster(size int, stdout, stderr io.Writer) (*TestCluster, error) {
+	tmpPath, err := ioutil.TempDir("", "gozk")
+	if err != nil {
+		return nil, err
+	}
+	success := false
+	startPort := int(rand.Int31n(6000) + 10000)
+	cluster := &TestCluster{Path: tmpPath}
+	defer func() {
+		if !success {
+			cluster.Stop()
+		}
+	}()
+	for serverN := 0; serverN < size; serverN++ {
+		srvPath := filepath.Join(tmpPath, fmt.Sprintf("srv%d", serverN))
+		if err := os.Mkdir(srvPath, 0700); err != nil {
+			return nil, err
+		}
+		port := startPort + serverN*3
+		cfg := ServerConfig{
+			ClientPort: port,
+			DataDir:    srvPath,
+		}
+		for i := 0; i < size; i++ {
+			cfg.Servers = append(cfg.Servers, ServerConfigServer{
+				ID:                 i + 1,
+				Host:               "127.0.0.1",
+				PeerPort:           startPort + i*3 + 1,
+				LeaderElectionPort: startPort + i*3 + 2,
+			})
+		}
+		cfgPath := filepath.Join(srvPath, "zoo.cfg")
+		fi, err := os.Create(cfgPath)
+		if err != nil {
+			return nil, err
+		}
+		err = cfg.Marshall(fi)
+		fi.Close()
+		if err != nil {
+			return nil, err
+		}
+
+		fi, err = os.Create(filepath.Join(srvPath, "myid"))
+		if err != nil {
+			return nil, err
+		}
+		_, err = fmt.Fprintf(fi, "%d\n", serverN+1)
+		fi.Close()
+		if err != nil {
+			return nil, err
+		}
+
+		srv := &Server{
+			ConfigPath: cfgPath,
+			Stdout:     stdout,
+			Stderr:     stderr,
+		}
+		if err := srv.Start(); err != nil {
+			return nil, err
+		}
+		cluster.Servers = append(cluster.Servers, TestServer{
+			Path: srvPath,
+			Port: cfg.ClientPort,
+			Srv:  srv,
+		})
+	}
+	if err := cluster.waitForStart(10, time.Second); err != nil {
+		return nil, err
+	}
+	success = true
+	return cluster, nil
+}
+
+func (ts *TestCluster) Connect(idx int) (*Conn, error) {
+	zk, _, err := Connect([]string{fmt.Sprintf("127.0.0.1:%d", ts.Servers[idx].Port)}, time.Second*15)
+	return zk, err
+}
+
+func (ts *TestCluster) ConnectAll() (*Conn, <-chan Event, error) {
+	return ts.ConnectAllTimeout(time.Second * 15)
+}
+
+func (ts *TestCluster) ConnectAllTimeout(sessionTimeout time.Duration) (*Conn, <-chan Event, error) {
+	hosts := make([]string, len(ts.Servers))
+	for i, srv := range ts.Servers {
+		hosts[i] = fmt.Sprintf("127.0.0.1:%d", srv.Port)
+	}
+	zk, ch, err := Connect(hosts, sessionTimeout)
+	return zk, ch, err
+}
+
+func (ts *TestCluster) Stop() error {
+	for _, srv := range ts.Servers {
+		srv.Srv.Stop()
+	}
+	defer os.RemoveAll(ts.Path)
+	return ts.waitForStop(5, time.Second)
+}
+
+// waitForStart blocks until the cluster is up
+func (ts *TestCluster) waitForStart(maxRetry int, interval time.Duration) error {
+	// verify that the servers are up with SRVR
+	serverAddrs := make([]string, len(ts.Servers))
+	for i, s := range ts.Servers {
+		serverAddrs[i] = fmt.Sprintf("127.0.0.1:%d", s.Port)
+	}
+
+	for i := 0; i < maxRetry; i++ {
+		_, ok := FLWSrvr(serverAddrs, time.Second)
+		if ok {
+			return nil
+		}
+		time.Sleep(interval)
+	}
+	return fmt.Errorf("unable to verify health of servers")
+}
+
+// waitForStop blocks until the cluster is down
+func (ts *TestCluster) waitForStop(maxRetry int, interval time.Duration) error {
+	// verify that the servers are up with RUOK
+	serverAddrs := make([]string, len(ts.Servers))
+	for i, s := range ts.Servers {
+		serverAddrs[i] = fmt.Sprintf("127.0.0.1:%d", s.Port)
+	}
+
+	var success bool
+	for i := 0; i < maxRetry && !success; i++ {
+		success = true
+		for _, ok := range FLWRuok(serverAddrs, time.Second) {
+			if ok {
+				success = false
+			}
+		}
+		if !success {
+			time.Sleep(interval)
+		}
+	}
+	if !success {
+		return fmt.Errorf("unable to verify servers are down")
+	}
+	return nil
+}
+
+func (tc *TestCluster) StartServer(server string) {
+	for _, s := range tc.Servers {
+		if strings.HasSuffix(server, fmt.Sprintf(":%d", s.Port)) {
+			s.Srv.Start()
+			return
+		}
+	}
+	panic(fmt.Sprintf("Unknown server: %s", server))
+}
+
+func (tc *TestCluster) StopServer(server string) {
+	for _, s := range tc.Servers {
+		if strings.HasSuffix(server, fmt.Sprintf(":%d", s.Port)) {
+			s.Srv.Stop()
+			return
+		}
+	}
+	panic(fmt.Sprintf("Unknown server: %s", server))
+}

vendor/github.com/samuel/go-zookeeper/zk/server_java.go

@@ -0,0 +1,136 @@
+package zk
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+type ErrMissingServerConfigField string
+
+func (e ErrMissingServerConfigField) Error() string {
+	return fmt.Sprintf("zk: missing server config field '%s'", string(e))
+}
+
+const (
+	DefaultServerTickTime                 = 2000
+	DefaultServerInitLimit                = 10
+	DefaultServerSyncLimit                = 5
+	DefaultServerAutoPurgeSnapRetainCount = 3
+	DefaultPeerPort                       = 2888
+	DefaultLeaderElectionPort             = 3888
+)
+
+type ServerConfigServer struct {
+	ID                 int
+	Host               string
+	PeerPort           int
+	LeaderElectionPort int
+}
+
+type ServerConfig struct {
+	TickTime                 int    // Number of milliseconds of each tick
+	InitLimit                int    // Number of ticks that the initial synchronization phase can take
+	SyncLimit                int    // Number of ticks that can pass between sending a request and getting an acknowledgement
+	DataDir                  string // Direcrory where the snapshot is stored
+	ClientPort               int    // Port at which clients will connect
+	AutoPurgeSnapRetainCount int    // Number of snapshots to retain in dataDir
+	AutoPurgePurgeInterval   int    // Purge task internal in hours (0 to disable auto purge)
+	Servers                  []ServerConfigServer
+}
+
+func (sc ServerConfig) Marshall(w io.Writer) error {
+	if sc.DataDir == "" {
+		return ErrMissingServerConfigField("dataDir")
+	}
+	fmt.Fprintf(w, "dataDir=%s\n", sc.DataDir)
+	if sc.TickTime <= 0 {
+		sc.TickTime = DefaultServerTickTime
+	}
+	fmt.Fprintf(w, "tickTime=%d\n", sc.TickTime)
+	if sc.InitLimit <= 0 {
+		sc.InitLimit = DefaultServerInitLimit
+	}
+	fmt.Fprintf(w, "initLimit=%d\n", sc.InitLimit)
+	if sc.SyncLimit <= 0 {
+		sc.SyncLimit = DefaultServerSyncLimit
+	}
+	fmt.Fprintf(w, "syncLimit=%d\n", sc.SyncLimit)
+	if sc.ClientPort <= 0 {
+		sc.ClientPort = DefaultPort
+	}
+	fmt.Fprintf(w, "clientPort=%d\n", sc.ClientPort)
+	if sc.AutoPurgePurgeInterval > 0 {
+		if sc.AutoPurgeSnapRetainCount <= 0 {
+			sc.AutoPurgeSnapRetainCount = DefaultServerAutoPurgeSnapRetainCount
+		}
+		fmt.Fprintf(w, "autopurge.snapRetainCount=%d\n", sc.AutoPurgeSnapRetainCount)
+		fmt.Fprintf(w, "autopurge.purgeInterval=%d\n", sc.AutoPurgePurgeInterval)
+	}
+	if len(sc.Servers) > 0 {
+		for _, srv := range sc.Servers {
+			if srv.PeerPort <= 0 {
+				srv.PeerPort = DefaultPeerPort
+			}
+			if srv.LeaderElectionPort <= 0 {
+				srv.LeaderElectionPort = DefaultLeaderElectionPort
+			}
+			fmt.Fprintf(w, "server.%d=%s:%d:%d\n", srv.ID, srv.Host, srv.PeerPort, srv.LeaderElectionPort)
+		}
+	}
+	return nil
+}
+
+var jarSearchPaths = []string{
+	"zookeeper-*/contrib/fatjar/zookeeper-*-fatjar.jar",
+	"../zookeeper-*/contrib/fatjar/zookeeper-*-fatjar.jar",
+	"/usr/share/java/zookeeper-*.jar",
+	"/usr/local/zookeeper-*/contrib/fatjar/zookeeper-*-fatjar.jar",
+	"/usr/local/Cellar/zookeeper/*/libexec/contrib/fatjar/zookeeper-*-fatjar.jar",
+}
+
+func findZookeeperFatJar() string {
+	var paths []string
+	zkPath := os.Getenv("ZOOKEEPER_PATH")
+	if zkPath == "" {
+		paths = jarSearchPaths
+	} else {
+		paths = []string{filepath.Join(zkPath, "contrib/fatjar/zookeeper-*-fatjar.jar")}
+	}
+	for _, path := range paths {
+		matches, _ := filepath.Glob(path)
+		// TODO: could sort by version and pick latest
+		if len(matches) > 0 {
+			return matches[0]
+		}
+	}
+	return ""
+}
+
+type Server struct {
+	JarPath        string
+	ConfigPath     string
+	Stdout, Stderr io.Writer
+
+	cmd *exec.Cmd
+}
+
+func (srv *Server) Start() error {
+	if srv.JarPath == "" {
+		srv.JarPath = findZookeeperFatJar()
+		if srv.JarPath == "" {
+			return fmt.Errorf("zk: unable to find server jar")
+		}
+	}
+	srv.cmd = exec.Command("java", "-jar", srv.JarPath, "server", srv.ConfigPath)
+	srv.cmd.Stdout = srv.Stdout
+	srv.cmd.Stderr = srv.Stderr
+	return srv.cmd.Start()
+}
+
+func (srv *Server) Stop() error {
+	srv.cmd.Process.Signal(os.Kill)
+	return srv.cmd.Wait()
+}

vendor/github.com/samuel/go-zookeeper/zk/structs.go

@@ -0,0 +1,600 @@
+package zk
+
+import (
+	"encoding/binary"
+	"errors"
+	"log"
+	"reflect"
+	"runtime"
+	"time"
+)
+
+var (
+	ErrUnhandledFieldType = errors.New("zk: unhandled field type")
+	ErrPtrExpected        = errors.New("zk: encode/decode expect a non-nil pointer to struct")
+	ErrShortBuffer        = errors.New("zk: buffer too small")
+)
+
+type defaultLogger struct{}
+
+func (defaultLogger) Printf(format string, a ...interface{}) {
+	log.Printf(format, a...)
+}
+
+type ACL struct {
+	Perms  int32
+	Scheme string
+	ID     string
+}
+
+type Stat struct {
+	Czxid          int64 // The zxid of the change that caused this znode to be created.
+	Mzxid          int64 // The zxid of the change that last modified this znode.
+	Ctime          int64 // The time in milliseconds from epoch when this znode was created.
+	Mtime          int64 // The time in milliseconds from epoch when this znode was last modified.
+	Version        int32 // The number of changes to the data of this znode.
+	Cversion       int32 // The number of changes to the children of this znode.
+	Aversion       int32 // The number of changes to the ACL of this znode.
+	EphemeralOwner int64 // The session id of the owner of this znode if the znode is an ephemeral node. If it is not an ephemeral node, it will be zero.
+	DataLength     int32 // The length of the data field of this znode.
+	NumChildren    int32 // The number of children of this znode.
+	Pzxid          int64 // last modified children
+}
+
+// ServerClient is the information for a single Zookeeper client and its session.
+// This is used to parse/extract the output fo the `cons` command.
+type ServerClient struct {
+	Queued        int64
+	Received      int64
+	Sent          int64
+	SessionID     int64
+	Lcxid         int64
+	Lzxid         int64
+	Timeout       int32
+	LastLatency   int32
+	MinLatency    int32
+	AvgLatency    int32
+	MaxLatency    int32
+	Established   time.Time
+	LastResponse  time.Time
+	Addr          string
+	LastOperation string // maybe?
+	Error         error
+}
+
+// ServerClients is a struct for the FLWCons() function. It's used to provide
+// the list of Clients.
+//
+// This is needed because FLWCons() takes multiple servers.
+type ServerClients struct {
+	Clients []*ServerClient
+	Error   error
+}
+
+// ServerStats is the information pulled from the Zookeeper `stat` command.
+type ServerStats struct {
+	Sent        int64
+	Received    int64
+	NodeCount   int64
+	MinLatency  int64
+	AvgLatency  int64
+	MaxLatency  int64
+	Connections int64
+	Outstanding int64
+	Epoch       int32
+	Counter     int32
+	BuildTime   time.Time
+	Mode        Mode
+	Version     string
+	Error       error
+}
+
+type requestHeader struct {
+	Xid    int32
+	Opcode int32
+}
+
+type responseHeader struct {
+	Xid  int32
+	Zxid int64
+	Err  ErrCode
+}
+
+type multiHeader struct {
+	Type int32
+	Done bool
+	Err  ErrCode
+}
+
+type auth struct {
+	Type   int32
+	Scheme string
+	Auth   []byte
+}
+
+// Generic request structs
+
+type pathRequest struct {
+	Path string
+}
+
+type PathVersionRequest struct {
+	Path    string
+	Version int32
+}
+
+type pathWatchRequest struct {
+	Path  string
+	Watch bool
+}
+
+type pathResponse struct {
+	Path string
+}
+
+type statResponse struct {
+	Stat Stat
+}
+
+//
+
+type CheckVersionRequest PathVersionRequest
+type closeRequest struct{}
+type closeResponse struct{}
+
+type connectRequest struct {
+	ProtocolVersion int32
+	LastZxidSeen    int64
+	TimeOut         int32
+	SessionID       int64
+	Passwd          []byte
+}
+
+type connectResponse struct {
+	ProtocolVersion int32
+	TimeOut         int32
+	SessionID       int64
+	Passwd          []byte
+}
+
+type CreateRequest struct {
+	Path  string
+	Data  []byte
+	Acl   []ACL
+	Flags int32
+}
+
+type createResponse pathResponse
+type DeleteRequest PathVersionRequest
+type deleteResponse struct{}
+
+type errorResponse struct {
+	Err int32
+}
+
+type existsRequest pathWatchRequest
+type existsResponse statResponse
+type getAclRequest pathRequest
+
+type getAclResponse struct {
+	Acl  []ACL
+	Stat Stat
+}
+
+type getChildrenRequest pathRequest
+
+type getChildrenResponse struct {
+	Children []string
+}
+
+type getChildren2Request pathWatchRequest
+
+type getChildren2Response struct {
+	Children []string
+	Stat     Stat
+}
+
+type getDataRequest pathWatchRequest
+
+type getDataResponse struct {
+	Data []byte
+	Stat Stat
+}
+
+type getMaxChildrenRequest pathRequest
+
+type getMaxChildrenResponse struct {
+	Max int32
+}
+
+type getSaslRequest struct {
+	Token []byte
+}
+
+type pingRequest struct{}
+type pingResponse struct{}
+
+type setAclRequest struct {
+	Path    string
+	Acl     []ACL
+	Version int32
+}
+
+type setAclResponse statResponse
+
+type SetDataRequest struct {
+	Path    string
+	Data    []byte
+	Version int32
+}
+
+type setDataResponse statResponse
+
+type setMaxChildren struct {
+	Path string
+	Max  int32
+}
+
+type setSaslRequest struct {
+	Token string
+}
+
+type setSaslResponse struct {
+	Token string
+}
+
+type setWatchesRequest struct {
+	RelativeZxid int64
+	DataWatches  []string
+	ExistWatches []string
+	ChildWatches []string
+}
+
+type setWatchesResponse struct{}
+
+type syncRequest pathRequest
+type syncResponse pathResponse
+
+type setAuthRequest auth
+type setAuthResponse struct{}
+
+type multiRequestOp struct {
+	Header multiHeader
+	Op     interface{}
+}
+type multiRequest struct {
+	Ops        []multiRequestOp
+	DoneHeader multiHeader
+}
+type multiResponseOp struct {
+	Header multiHeader
+	String string
+	Stat   *Stat
+}
+type multiResponse struct {
+	Ops        []multiResponseOp
+	DoneHeader multiHeader
+}
+
+func (r *multiRequest) Encode(buf []byte) (int, error) {
+	total := 0
+	for _, op := range r.Ops {
+		op.Header.Done = false
+		n, err := encodePacketValue(buf[total:], reflect.ValueOf(op))
+		if err != nil {
+			return total, err
+		}
+		total += n
+	}
+	r.DoneHeader.Done = true
+	n, err := encodePacketValue(buf[total:], reflect.ValueOf(r.DoneHeader))
+	if err != nil {
+		return total, err
+	}
+	total += n
+
+	return total, nil
+}
+
+func (r *multiRequest) Decode(buf []byte) (int, error) {
+	r.Ops = make([]multiRequestOp, 0)
+	r.DoneHeader = multiHeader{-1, true, -1}
+	total := 0
+	for {
+		header := &multiHeader{}
+		n, err := decodePacketValue(buf[total:], reflect.ValueOf(header))
+		if err != nil {
+			return total, err
+		}
+		total += n
+		if header.Done {
+			r.DoneHeader = *header
+			break
+		}
+
+		req := requestStructForOp(header.Type)
+		if req == nil {
+			return total, ErrAPIError
+		}
+		n, err = decodePacketValue(buf[total:], reflect.ValueOf(req))
+		if err != nil {
+			return total, err
+		}
+		total += n
+		r.Ops = append(r.Ops, multiRequestOp{*header, req})
+	}
+	return total, nil
+}
+
+func (r *multiResponse) Decode(buf []byte) (int, error) {
+	r.Ops = make([]multiResponseOp, 0)
+	r.DoneHeader = multiHeader{-1, true, -1}
+	total := 0
+	for {
+		header := &multiHeader{}
+		n, err := decodePacketValue(buf[total:], reflect.ValueOf(header))
+		if err != nil {
+			return total, err
+		}
+		total += n
+		if header.Done {
+			r.DoneHeader = *header
+			break
+		}
+
+		res := multiResponseOp{Header: *header}
+		var w reflect.Value
+		switch header.Type {
+		default:
+			return total, ErrAPIError
+		case opCreate:
+			w = reflect.ValueOf(&res.String)
+		case opSetData:
+			res.Stat = new(Stat)
+			w = reflect.ValueOf(res.Stat)
+		case opCheck, opDelete:
+		}
+		if w.IsValid() {
+			n, err := decodePacketValue(buf[total:], w)
+			if err != nil {
+				return total, err
+			}
+			total += n
+		}
+		r.Ops = append(r.Ops, res)
+	}
+	return total, nil
+}
+
+type watcherEvent struct {
+	Type  EventType
+	State State
+	Path  string
+}
+
+type decoder interface {
+	Decode(buf []byte) (int, error)
+}
+
+type encoder interface {
+	Encode(buf []byte) (int, error)
+}
+
+func decodePacket(buf []byte, st interface{}) (n int, err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			if e, ok := r.(runtime.Error); ok && e.Error() == "runtime error: slice bounds out of range" {
+				err = ErrShortBuffer
+			} else {
+				panic(r)
+			}
+		}
+	}()
+
+	v := reflect.ValueOf(st)
+	if v.Kind() != reflect.Ptr || v.IsNil() {
+		return 0, ErrPtrExpected
+	}
+	return decodePacketValue(buf, v)
+}
+
+func decodePacketValue(buf []byte, v reflect.Value) (int, error) {
+	rv := v
+	kind := v.Kind()
+	if kind == reflect.Ptr {
+		if v.IsNil() {
+			v.Set(reflect.New(v.Type().Elem()))
+		}
+		v = v.Elem()
+		kind = v.Kind()
+	}
+
+	n := 0
+	switch kind {
+	default:
+		return n, ErrUnhandledFieldType
+	case reflect.Struct:
+		if de, ok := rv.Interface().(decoder); ok {
+			return de.Decode(buf)
+		} else if de, ok := v.Interface().(decoder); ok {
+			return de.Decode(buf)
+		} else {
+			for i := 0; i < v.NumField(); i++ {
+				field := v.Field(i)
+				n2, err := decodePacketValue(buf[n:], field)
+				n += n2
+				if err != nil {
+					return n, err
+				}
+			}
+		}
+	case reflect.Bool:
+		v.SetBool(buf[n] != 0)
+		n++
+	case reflect.Int32:
+		v.SetInt(int64(binary.BigEndian.Uint32(buf[n : n+4])))
+		n += 4
+	case reflect.Int64:
+		v.SetInt(int64(binary.BigEndian.Uint64(buf[n : n+8])))
+		n += 8
+	case reflect.String:
+		ln := int(binary.BigEndian.Uint32(buf[n : n+4]))
+		v.SetString(string(buf[n+4 : n+4+ln]))
+		n += 4 + ln
+	case reflect.Slice:
+		switch v.Type().Elem().Kind() {
+		default:
+			count := int(binary.BigEndian.Uint32(buf[n : n+4]))
+			n += 4
+			values := reflect.MakeSlice(v.Type(), count, count)
+			v.Set(values)
+			for i := 0; i < count; i++ {
+				n2, err := decodePacketValue(buf[n:], values.Index(i))
+				n += n2
+				if err != nil {
+					return n, err
+				}
+			}
+		case reflect.Uint8:
+			ln := int(int32(binary.BigEndian.Uint32(buf[n : n+4])))
+			if ln < 0 {
+				n += 4
+				v.SetBytes(nil)
+			} else {
+				bytes := make([]byte, ln)
+				copy(bytes, buf[n+4:n+4+ln])
+				v.SetBytes(bytes)
+				n += 4 + ln
+			}
+		}
+	}
+	return n, nil
+}
+
+func encodePacket(buf []byte, st interface{}) (n int, err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			if e, ok := r.(runtime.Error); ok && e.Error() == "runtime error: slice bounds out of range" {
+				err = ErrShortBuffer
+			} else {
+				panic(r)
+			}
+		}
+	}()
+
+	v := reflect.ValueOf(st)
+	if v.Kind() != reflect.Ptr || v.IsNil() {
+		return 0, ErrPtrExpected
+	}
+	return encodePacketValue(buf, v)
+}
+
+func encodePacketValue(buf []byte, v reflect.Value) (int, error) {
+	rv := v
+	for v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface {
+		v = v.Elem()
+	}
+
+	n := 0
+	switch v.Kind() {
+	default:
+		return n, ErrUnhandledFieldType
+	case reflect.Struct:
+		if en, ok := rv.Interface().(encoder); ok {
+			return en.Encode(buf)
+		} else if en, ok := v.Interface().(encoder); ok {
+			return en.Encode(buf)
+		} else {
+			for i := 0; i < v.NumField(); i++ {
+				field := v.Field(i)
+				n2, err := encodePacketValue(buf[n:], field)
+				n += n2
+				if err != nil {
+					return n, err
+				}
+			}
+		}
+	case reflect.Bool:
+		if v.Bool() {
+			buf[n] = 1
+		} else {
+			buf[n] = 0
+		}
+		n++
+	case reflect.Int32:
+		binary.BigEndian.PutUint32(buf[n:n+4], uint32(v.Int()))
+		n += 4
+	case reflect.Int64:
+		binary.BigEndian.PutUint64(buf[n:n+8], uint64(v.Int()))
+		n += 8
+	case reflect.String:
+		str := v.String()
+		binary.BigEndian.PutUint32(buf[n:n+4], uint32(len(str)))
+		copy(buf[n+4:n+4+len(str)], []byte(str))
+		n += 4 + len(str)
+	case reflect.Slice:
+		switch v.Type().Elem().Kind() {
+		default:
+			count := v.Len()
+			startN := n
+			n += 4
+			for i := 0; i < count; i++ {
+				n2, err := encodePacketValue(buf[n:], v.Index(i))
+				n += n2
+				if err != nil {
+					return n, err
+				}
+			}
+			binary.BigEndian.PutUint32(buf[startN:startN+4], uint32(count))
+		case reflect.Uint8:
+			if v.IsNil() {
+				binary.BigEndian.PutUint32(buf[n:n+4], uint32(0xffffffff))
+				n += 4
+			} else {
+				bytes := v.Bytes()
+				binary.BigEndian.PutUint32(buf[n:n+4], uint32(len(bytes)))
+				copy(buf[n+4:n+4+len(bytes)], bytes)
+				n += 4 + len(bytes)
+			}
+		}
+	}
+	return n, nil
+}
+
+func requestStructForOp(op int32) interface{} {
+	switch op {
+	case opClose:
+		return &closeRequest{}
+	case opCreate:
+		return &CreateRequest{}
+	case opDelete:
+		return &DeleteRequest{}
+	case opExists:
+		return &existsRequest{}
+	case opGetAcl:
+		return &getAclRequest{}
+	case opGetChildren:
+		return &getChildrenRequest{}
+	case opGetChildren2:
+		return &getChildren2Request{}
+	case opGetData:
+		return &getDataRequest{}
+	case opPing:
+		return &pingRequest{}
+	case opSetAcl:
+		return &setAclRequest{}
+	case opSetData:
+		return &SetDataRequest{}
+	case opSetWatches:
+		return &setWatchesRequest{}
+	case opSync:
+		return &syncRequest{}
+	case opSetAuth:
+		return &setAuthRequest{}
+	case opCheck:
+		return &CheckVersionRequest{}
+	case opMulti:
+		return &multiRequest{}
+	}
+	return nil
+}

vendor/github.com/samuel/go-zookeeper/zk/util.go

@@ -0,0 +1,54 @@
+package zk
+
+import (
+	"crypto/sha1"
+	"encoding/base64"
+	"fmt"
+	"math/rand"
+	"strconv"
+	"strings"
+)
+
+// AuthACL produces an ACL list containing a single ACL which uses the
+// provided permissions, with the scheme "auth", and ID "", which is used
+// by ZooKeeper to represent any authenticated user.
+func AuthACL(perms int32) []ACL {
+	return []ACL{{perms, "auth", ""}}
+}
+
+// WorldACL produces an ACL list containing a single ACL which uses the
+// provided permissions, with the scheme "world", and ID "anyone", which
+// is used by ZooKeeper to represent any user at all.
+func WorldACL(perms int32) []ACL {
+	return []ACL{{perms, "world", "anyone"}}
+}
+
+func DigestACL(perms int32, user, password string) []ACL {
+	userPass := []byte(fmt.Sprintf("%s:%s", user, password))
+	h := sha1.New()
+	if n, err := h.Write(userPass); err != nil || n != len(userPass) {
+		panic("SHA1 failed")
+	}
+	digest := base64.StdEncoding.EncodeToString(h.Sum(nil))
+	return []ACL{{perms, "digest", fmt.Sprintf("%s:%s", user, digest)}}
+}
+
+// FormatServers takes a slice of addresses, and makes sure they are in a format
+// that resembles <addr>:<port>. If the server has no port provided, the
+// DefaultPort constant is added to the end.
+func FormatServers(servers []string) []string {
+	for i := range servers {
+		if !strings.Contains(servers[i], ":") {
+			servers[i] = servers[i] + ":" + strconv.Itoa(DefaultPort)
+		}
+	}
+	return servers
+}
+
+// stringShuffle performs a Fisher-Yates shuffle on a slice of strings
+func stringShuffle(s []string) {
+	for i := len(s) - 1; i > 0; i-- {
+		j := rand.Intn(i + 1)
+		s[i], s[j] = s[j], s[i]
+	}
+}