diff --git a/vendor/github.com/coreos/etcd/pkg/contention/contention.go b/vendor/github.com/coreos/etcd/pkg/contention/contention.go
new file mode 100644
index 0000000..26ce9a2
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/pkg/contention/contention.go
@@ -0,0 +1,69 @@
+// Copyright 2016 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 contention
+
+import (
+	"sync"
+	"time"
+)
+
+// TimeoutDetector detects routine starvations by
+// observing the actual time duration to finish an action
+// or between two events that should happen in a fixed
+// interval. If the observed duration is longer than
+// the expectation, the detector will report the result.
+type TimeoutDetector struct {
+	mu          sync.Mutex // protects all
+	maxDuration time.Duration
+	// map from event to time
+	// time is the last seen time of the event.
+	records map[uint64]time.Time
+}
+
+// NewTimeoutDetector creates the TimeoutDetector.
+func NewTimeoutDetector(maxDuration time.Duration) *TimeoutDetector {
+	return &TimeoutDetector{
+		maxDuration: maxDuration,
+		records:     make(map[uint64]time.Time),
+	}
+}
+
+// Reset resets the NewTimeoutDetector.
+func (td *TimeoutDetector) Reset() {
+	td.mu.Lock()
+	defer td.mu.Unlock()
+
+	td.records = make(map[uint64]time.Time)
+}
+
+// Observe observes an event for given id. It returns false and exceeded duration
+// if the interval is longer than the expectation.
+func (td *TimeoutDetector) Observe(which uint64) (bool, time.Duration) {
+	td.mu.Lock()
+	defer td.mu.Unlock()
+
+	ok := true
+	now := time.Now()
+	exceed := time.Duration(0)
+
+	if pt, found := td.records[which]; found {
+		exceed = now.Sub(pt) - td.maxDuration
+		if exceed > 0 {
+			ok = false
+		}
+	}
+	td.records[which] = now
+	return ok, exceed
+}