Vendor main dependencies.

vendor/github.com/docker/libkv/store/zookeeper/zookeeper.go

@@ -0,0 +1,429 @@
+package zookeeper
+
+import (
+	"strings"
+	"time"
+
+	"github.com/docker/libkv"
+	"github.com/docker/libkv/store"
+	zk "github.com/samuel/go-zookeeper/zk"
+)
+
+const (
+	// SOH control character
+	SOH = "\x01"
+
+	defaultTimeout = 10 * time.Second
+)
+
+// Zookeeper is the receiver type for
+// the Store interface
+type Zookeeper struct {
+	timeout time.Duration
+	client  *zk.Conn
+}
+
+type zookeeperLock struct {
+	client *zk.Conn
+	lock   *zk.Lock
+	key    string
+	value  []byte
+}
+
+// Register registers zookeeper to libkv
+func Register() {
+	libkv.AddStore(store.ZK, New)
+}
+
+// New creates a new Zookeeper client given a
+// list of endpoints and an optional tls config
+func New(endpoints []string, options *store.Config) (store.Store, error) {
+	s := &Zookeeper{}
+	s.timeout = defaultTimeout
+
+	// Set options
+	if options != nil {
+		if options.ConnectionTimeout != 0 {
+			s.setTimeout(options.ConnectionTimeout)
+		}
+	}
+
+	// Connect to Zookeeper
+	conn, _, err := zk.Connect(endpoints, s.timeout)
+	if err != nil {
+		return nil, err
+	}
+	s.client = conn
+
+	return s, nil
+}
+
+// setTimeout sets the timeout for connecting to Zookeeper
+func (s *Zookeeper) setTimeout(time time.Duration) {
+	s.timeout = time
+}
+
+// Get the value at "key", returns the last modified index
+// to use in conjunction to Atomic calls
+func (s *Zookeeper) Get(key string) (pair *store.KVPair, err error) {
+	resp, meta, err := s.client.Get(s.normalize(key))
+
+	if err != nil {
+		if err == zk.ErrNoNode {
+			return nil, store.ErrKeyNotFound
+		}
+		return nil, err
+	}
+
+	// FIXME handle very rare cases where Get returns the
+	// SOH control character instead of the actual value
+	if string(resp) == SOH {
+		return s.Get(store.Normalize(key))
+	}
+
+	pair = &store.KVPair{
+		Key:       key,
+		Value:     resp,
+		LastIndex: uint64(meta.Version),
+	}
+
+	return pair, nil
+}
+
+// createFullPath creates the entire path for a directory
+// that does not exist
+func (s *Zookeeper) createFullPath(path []string, ephemeral bool) error {
+	for i := 1; i <= len(path); i++ {
+		newpath := "/" + strings.Join(path[:i], "/")
+		if i == len(path) && ephemeral {
+			_, err := s.client.Create(newpath, []byte{}, zk.FlagEphemeral, zk.WorldACL(zk.PermAll))
+			return err
+		}
+		_, err := s.client.Create(newpath, []byte{}, 0, zk.WorldACL(zk.PermAll))
+		if err != nil {
+			// Skip if node already exists
+			if err != zk.ErrNodeExists {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// Put a value at "key"
+func (s *Zookeeper) Put(key string, value []byte, opts *store.WriteOptions) error {
+	fkey := s.normalize(key)
+
+	exists, err := s.Exists(key)
+	if err != nil {
+		return err
+	}
+
+	if !exists {
+		if opts != nil && opts.TTL > 0 {
+			s.createFullPath(store.SplitKey(strings.TrimSuffix(key, "/")), true)
+		} else {
+			s.createFullPath(store.SplitKey(strings.TrimSuffix(key, "/")), false)
+		}
+	}
+
+	_, err = s.client.Set(fkey, value, -1)
+	return err
+}
+
+// Delete a value at "key"
+func (s *Zookeeper) Delete(key string) error {
+	err := s.client.Delete(s.normalize(key), -1)
+	if err == zk.ErrNoNode {
+		return store.ErrKeyNotFound
+	}
+	return err
+}
+
+// Exists checks if the key exists inside the store
+func (s *Zookeeper) Exists(key string) (bool, error) {
+	exists, _, err := s.client.Exists(s.normalize(key))
+	if err != nil {
+		return false, err
+	}
+	return exists, nil
+}
+
+// Watch for changes on a "key"
+// It returns a channel that will receive changes or pass
+// on errors. Upon creation, the current value will first
+// be sent to the channel. Providing a non-nil stopCh can
+// be used to stop watching.
+func (s *Zookeeper) Watch(key string, stopCh <-chan struct{}) (<-chan *store.KVPair, error) {
+	// Get the key first
+	pair, err := s.Get(key)
+	if err != nil {
+		return nil, err
+	}
+
+	// Catch zk notifications and fire changes into the channel.
+	watchCh := make(chan *store.KVPair)
+	go func() {
+		defer close(watchCh)
+
+		// Get returns the current value to the channel prior
+		// to listening to any event that may occur on that key
+		watchCh <- pair
+		for {
+			_, _, eventCh, err := s.client.GetW(s.normalize(key))
+			if err != nil {
+				return
+			}
+			select {
+			case e := <-eventCh:
+				if e.Type == zk.EventNodeDataChanged {
+					if entry, err := s.Get(key); err == nil {
+						watchCh <- entry
+					}
+				}
+			case <-stopCh:
+				// There is no way to stop GetW so just quit
+				return
+			}
+		}
+	}()
+
+	return watchCh, nil
+}
+
+// WatchTree watches for changes on a "directory"
+// It returns a channel that will receive changes or pass
+// on errors. Upon creating a watch, the current childs values
+// will be sent to the channel .Providing a non-nil stopCh can
+// be used to stop watching.
+func (s *Zookeeper) WatchTree(directory string, stopCh <-chan struct{}) (<-chan []*store.KVPair, error) {
+	// List the childrens first
+	entries, err := s.List(directory)
+	if err != nil {
+		return nil, err
+	}
+
+	// Catch zk notifications and fire changes into the channel.
+	watchCh := make(chan []*store.KVPair)
+	go func() {
+		defer close(watchCh)
+
+		// List returns the children values to the channel
+		// prior to listening to any events that may occur
+		// on those keys
+		watchCh <- entries
+
+		for {
+			_, _, eventCh, err := s.client.ChildrenW(s.normalize(directory))
+			if err != nil {
+				return
+			}
+			select {
+			case e := <-eventCh:
+				if e.Type == zk.EventNodeChildrenChanged {
+					if kv, err := s.List(directory); err == nil {
+						watchCh <- kv
+					}
+				}
+			case <-stopCh:
+				// There is no way to stop GetW so just quit
+				return
+			}
+		}
+	}()
+
+	return watchCh, nil
+}
+
+// List child nodes of a given directory
+func (s *Zookeeper) List(directory string) ([]*store.KVPair, error) {
+	keys, stat, err := s.client.Children(s.normalize(directory))
+	if err != nil {
+		if err == zk.ErrNoNode {
+			return nil, store.ErrKeyNotFound
+		}
+		return nil, err
+	}
+
+	kv := []*store.KVPair{}
+
+	// FIXME Costly Get request for each child key..
+	for _, key := range keys {
+		pair, err := s.Get(strings.TrimSuffix(directory, "/") + s.normalize(key))
+		if err != nil {
+			// If node is not found: List is out of date, retry
+			if err == zk.ErrNoNode {
+				return s.List(directory)
+			}
+			return nil, err
+		}
+
+		kv = append(kv, &store.KVPair{
+			Key:       key,
+			Value:     []byte(pair.Value),
+			LastIndex: uint64(stat.Version),
+		})
+	}
+
+	return kv, nil
+}
+
+// DeleteTree deletes a range of keys under a given directory
+func (s *Zookeeper) DeleteTree(directory string) error {
+	pairs, err := s.List(directory)
+	if err != nil {
+		return err
+	}
+
+	var reqs []interface{}
+
+	for _, pair := range pairs {
+		reqs = append(reqs, &zk.DeleteRequest{
+			Path:    s.normalize(directory + "/" + pair.Key),
+			Version: -1,
+		})
+	}
+
+	_, err = s.client.Multi(reqs...)
+	return err
+}
+
+// AtomicPut put a value at "key" if the key has not been
+// modified in the meantime, throws an error if this is the case
+func (s *Zookeeper) AtomicPut(key string, value []byte, previous *store.KVPair, _ *store.WriteOptions) (bool, *store.KVPair, error) {
+	var lastIndex uint64
+
+	if previous != nil {
+		meta, err := s.client.Set(s.normalize(key), value, int32(previous.LastIndex))
+		if err != nil {
+			// Compare Failed
+			if err == zk.ErrBadVersion {
+				return false, nil, store.ErrKeyModified
+			}
+			return false, nil, err
+		}
+		lastIndex = uint64(meta.Version)
+	} else {
+		// Interpret previous == nil as create operation.
+		_, err := s.client.Create(s.normalize(key), value, 0, zk.WorldACL(zk.PermAll))
+		if err != nil {
+			// Directory does not exist
+			if err == zk.ErrNoNode {
+
+				// Create the directory
+				parts := store.SplitKey(strings.TrimSuffix(key, "/"))
+				parts = parts[:len(parts)-1]
+				if err = s.createFullPath(parts, false); err != nil {
+					// Failed to create the directory.
+					return false, nil, err
+				}
+
+				// Create the node
+				if _, err := s.client.Create(s.normalize(key), value, 0, zk.WorldACL(zk.PermAll)); err != nil {
+					// Node exist error (when previous nil)
+					if err == zk.ErrNodeExists {
+						return false, nil, store.ErrKeyExists
+					}
+					return false, nil, err
+				}
+
+			} else {
+				// Node Exists error (when previous nil)
+				if err == zk.ErrNodeExists {
+					return false, nil, store.ErrKeyExists
+				}
+
+				// Unhandled error
+				return false, nil, err
+			}
+		}
+		lastIndex = 0 // Newly created nodes have version 0.
+	}
+
+	pair := &store.KVPair{
+		Key:       key,
+		Value:     value,
+		LastIndex: lastIndex,
+	}
+
+	return true, pair, nil
+}
+
+// AtomicDelete deletes a value at "key" if the key
+// has not been modified in the meantime, throws an
+// error if this is the case
+func (s *Zookeeper) AtomicDelete(key string, previous *store.KVPair) (bool, error) {
+	if previous == nil {
+		return false, store.ErrPreviousNotSpecified
+	}
+
+	err := s.client.Delete(s.normalize(key), int32(previous.LastIndex))
+	if err != nil {
+		// Key not found
+		if err == zk.ErrNoNode {
+			return false, store.ErrKeyNotFound
+		}
+		// Compare failed
+		if err == zk.ErrBadVersion {
+			return false, store.ErrKeyModified
+		}
+		// General store error
+		return false, err
+	}
+	return true, nil
+}
+
+// NewLock returns a handle to a lock struct which can
+// be used to provide mutual exclusion on a key
+func (s *Zookeeper) NewLock(key string, options *store.LockOptions) (lock store.Locker, err error) {
+	value := []byte("")
+
+	// Apply options
+	if options != nil {
+		if options.Value != nil {
+			value = options.Value
+		}
+	}
+
+	lock = &zookeeperLock{
+		client: s.client,
+		key:    s.normalize(key),
+		value:  value,
+		lock:   zk.NewLock(s.client, s.normalize(key), zk.WorldACL(zk.PermAll)),
+	}
+
+	return lock, err
+}
+
+// Lock attempts to acquire the lock and blocks while
+// doing so. It returns a channel that is closed if our
+// lock is lost or if an error occurs
+func (l *zookeeperLock) Lock(stopChan chan struct{}) (<-chan struct{}, error) {
+	err := l.lock.Lock()
+
+	if err == nil {
+		// We hold the lock, we can set our value
+		// FIXME: The value is left behind
+		// (problematic for leader election)
+		_, err = l.client.Set(l.key, l.value, -1)
+	}
+
+	return make(chan struct{}), err
+}
+
+// Unlock the "key". Calling unlock while
+// not holding the lock will throw an error
+func (l *zookeeperLock) Unlock() error {
+	return l.lock.Unlock()
+}
+
+// Close closes the client connection
+func (s *Zookeeper) Close() {
+	s.client.Close()
+}
+
+// Normalize the key for usage in Zookeeper
+func (s *Zookeeper) normalize(key string) string {
+	key = store.Normalize(key)
+	return strings.TrimSuffix(key, "/")
+}