diff --git a/vendor/github.com/coreos/etcd/store/event_history.go b/vendor/github.com/coreos/etcd/store/event_history.go
new file mode 100644
index 0000000..235d87a
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/store/event_history.go
@@ -0,0 +1,129 @@
+// Copyright 2015 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package store
+
+import (
+	"fmt"
+	"path"
+	"strings"
+	"sync"
+
+	etcdErr "github.com/coreos/etcd/error"
+)
+
+type EventHistory struct {
+	Queue      eventQueue
+	StartIndex uint64
+	LastIndex  uint64
+	rwl        sync.RWMutex
+}
+
+func newEventHistory(capacity int) *EventHistory {
+	return &EventHistory{
+		Queue: eventQueue{
+			Capacity: capacity,
+			Events:   make([]*Event, capacity),
+		},
+	}
+}
+
+// addEvent function adds event into the eventHistory
+func (eh *EventHistory) addEvent(e *Event) *Event {
+	eh.rwl.Lock()
+	defer eh.rwl.Unlock()
+
+	eh.Queue.insert(e)
+
+	eh.LastIndex = e.Index()
+
+	eh.StartIndex = eh.Queue.Events[eh.Queue.Front].Index()
+
+	return e
+}
+
+// scan enumerates events from the index history and stops at the first point
+// where the key matches.
+func (eh *EventHistory) scan(key string, recursive bool, index uint64) (*Event, *etcdErr.Error) {
+	eh.rwl.RLock()
+	defer eh.rwl.RUnlock()
+
+	// index should be after the event history's StartIndex
+	if index < eh.StartIndex {
+		return nil,
+			etcdErr.NewError(etcdErr.EcodeEventIndexCleared,
+				fmt.Sprintf("the requested history has been cleared [%v/%v]",
+					eh.StartIndex, index), 0)
+	}
+
+	// the index should come before the size of the queue minus the duplicate count
+	if index > eh.LastIndex { // future index
+		return nil, nil
+	}
+
+	offset := index - eh.StartIndex
+	i := (eh.Queue.Front + int(offset)) % eh.Queue.Capacity
+
+	for {
+		e := eh.Queue.Events[i]
+
+		if !e.Refresh {
+			ok := (e.Node.Key == key)
+
+			if recursive {
+				// add tailing slash
+				nkey := path.Clean(key)
+				if nkey[len(nkey)-1] != '/' {
+					nkey = nkey + "/"
+				}
+
+				ok = ok || strings.HasPrefix(e.Node.Key, nkey)
+			}
+
+			if (e.Action == Delete || e.Action == Expire) && e.PrevNode != nil && e.PrevNode.Dir {
+				ok = ok || strings.HasPrefix(key, e.PrevNode.Key)
+			}
+
+			if ok {
+				return e, nil
+			}
+		}
+
+		i = (i + 1) % eh.Queue.Capacity
+
+		if i == eh.Queue.Back {
+			return nil, nil
+		}
+	}
+}
+
+// clone will be protected by a stop-world lock
+// do not need to obtain internal lock
+func (eh *EventHistory) clone() *EventHistory {
+	clonedQueue := eventQueue{
+		Capacity: eh.Queue.Capacity,
+		Events:   make([]*Event, eh.Queue.Capacity),
+		Size:     eh.Queue.Size,
+		Front:    eh.Queue.Front,
+		Back:     eh.Queue.Back,
+	}
+
+	copy(clonedQueue.Events, eh.Queue.Events)
+	return &EventHistory{
+		StartIndex: eh.StartIndex,
+		Queue:      clonedQueue,
+		LastIndex:  eh.LastIndex,
+	}
+
+}