Fresh dep ensure

vendor/k8s.io/kubernetes/pkg/util/keymutex/hashed.go

@@ -0,0 +1,64 @@
+/*
+Copyright 2018 The Kubernetes 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 keymutex
+
+import (
+	"hash/fnv"
+	"runtime"
+	"sync"
+
+	"k8s.io/klog"
+)
+
+// NewHashed returns a new instance of KeyMutex which hashes arbitrary keys to
+// a fixed set of locks. `n` specifies number of locks, if n <= 0, we use
+// number of cpus.
+// Note that because it uses fixed set of locks, different keys may share same
+// lock, so it's possible to wait on same lock.
+func NewHashed(n int) KeyMutex {
+	if n <= 0 {
+		n = runtime.NumCPU()
+	}
+	return &hashedKeyMutex{
+		mutexes: make([]sync.Mutex, n),
+	}
+}
+
+type hashedKeyMutex struct {
+	mutexes []sync.Mutex
+}
+
+// Acquires a lock associated with the specified ID.
+func (km *hashedKeyMutex) LockKey(id string) {
+	klog.V(5).Infof("hashedKeyMutex.LockKey(...) called for id %q\r\n", id)
+	km.mutexes[km.hash(id)%len(km.mutexes)].Lock()
+	klog.V(5).Infof("hashedKeyMutex.LockKey(...) for id %q completed.\r\n", id)
+}
+
+// Releases the lock associated with the specified ID.
+func (km *hashedKeyMutex) UnlockKey(id string) error {
+	klog.V(5).Infof("hashedKeyMutex.UnlockKey(...) called for id %q\r\n", id)
+	km.mutexes[km.hash(id)%len(km.mutexes)].Unlock()
+	klog.V(5).Infof("hashedKeyMutex.UnlockKey(...) for id %q completed.\r\n", id)
+	return nil
+}
+
+func (km *hashedKeyMutex) hash(id string) int {
+	h := fnv.New32a()
+	h.Write([]byte(id))
+	return int(h.Sum32())
+}