diff --git a/vendor/github.com/coreos/etcd/pkg/wait/wait.go b/vendor/github.com/coreos/etcd/pkg/wait/wait.go
new file mode 100644
index 0000000..9b1df41
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/pkg/wait/wait.go
@@ -0,0 +1,91 @@
+// 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 wait provides utility functions for polling, listening using Go
+// channel.
+package wait
+
+import (
+	"log"
+	"sync"
+)
+
+// Wait is an interface that provides the ability to wait and trigger events that
+// are associated with IDs.
+type Wait interface {
+	// Register waits returns a chan that waits on the given ID.
+	// The chan will be triggered when Trigger is called with
+	// the same ID.
+	Register(id uint64) <-chan interface{}
+	// Trigger triggers the waiting chans with the given ID.
+	Trigger(id uint64, x interface{})
+	IsRegistered(id uint64) bool
+}
+
+type list struct {
+	l sync.RWMutex
+	m map[uint64]chan interface{}
+}
+
+// New creates a Wait.
+func New() Wait {
+	return &list{m: make(map[uint64]chan interface{})}
+}
+
+func (w *list) Register(id uint64) <-chan interface{} {
+	w.l.Lock()
+	defer w.l.Unlock()
+	ch := w.m[id]
+	if ch == nil {
+		ch = make(chan interface{}, 1)
+		w.m[id] = ch
+	} else {
+		log.Panicf("dup id %x", id)
+	}
+	return ch
+}
+
+func (w *list) Trigger(id uint64, x interface{}) {
+	w.l.Lock()
+	ch := w.m[id]
+	delete(w.m, id)
+	w.l.Unlock()
+	if ch != nil {
+		ch <- x
+		close(ch)
+	}
+}
+
+func (w *list) IsRegistered(id uint64) bool {
+	w.l.RLock()
+	defer w.l.RUnlock()
+	_, ok := w.m[id]
+	return ok
+}
+
+type waitWithResponse struct {
+	ch <-chan interface{}
+}
+
+func NewWithResponse(ch <-chan interface{}) Wait {
+	return &waitWithResponse{ch: ch}
+}
+
+func (w *waitWithResponse) Register(id uint64) <-chan interface{} {
+	return w.ch
+}
+func (w *waitWithResponse) Trigger(id uint64, x interface{}) {}
+func (w *waitWithResponse) IsRegistered(id uint64) bool {
+	panic("waitWithResponse.IsRegistered() shouldn't be called")
+}