84 lines
2.3 KiB
Go
84 lines
2.3 KiB
Go
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/*
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Copyright 2015 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package keymutex
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import (
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"fmt"
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"sync"
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"github.com/golang/glog"
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)
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// KeyMutex is a thread-safe interface for acquiring locks on arbitrary strings.
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type KeyMutex interface {
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// Acquires a lock associated with the specified ID, creates the lock if one doesn't already exist.
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LockKey(id string)
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// Releases the lock associated with the specified ID.
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// Returns an error if the specified ID doesn't exist.
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UnlockKey(id string) error
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}
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// Returns a new instance of a key mutex.
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func NewKeyMutex() KeyMutex {
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return &keyMutex{
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mutexMap: make(map[string]*sync.Mutex),
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}
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}
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type keyMutex struct {
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sync.RWMutex
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mutexMap map[string]*sync.Mutex
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}
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// Acquires a lock associated with the specified ID (creates the lock if one doesn't already exist).
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func (km *keyMutex) LockKey(id string) {
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glog.V(5).Infof("LockKey(...) called for id %q\r\n", id)
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mutex := km.getOrCreateLock(id)
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mutex.Lock()
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glog.V(5).Infof("LockKey(...) for id %q completed.\r\n", id)
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}
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// Releases the lock associated with the specified ID.
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// Returns an error if the specified ID doesn't exist.
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func (km *keyMutex) UnlockKey(id string) error {
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glog.V(5).Infof("UnlockKey(...) called for id %q\r\n", id)
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km.RLock()
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defer km.RUnlock()
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mutex, exists := km.mutexMap[id]
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if !exists {
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return fmt.Errorf("id %q not found", id)
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}
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glog.V(5).Infof("UnlockKey(...) for id. Mutex found, trying to unlock it. %q\r\n", id)
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mutex.Unlock()
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glog.V(5).Infof("UnlockKey(...) for id %q completed.\r\n", id)
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return nil
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}
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// Returns lock associated with the specified ID, or creates the lock if one doesn't already exist.
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func (km *keyMutex) getOrCreateLock(id string) *sync.Mutex {
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km.Lock()
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defer km.Unlock()
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if _, exists := km.mutexMap[id]; !exists {
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km.mutexMap[id] = &sync.Mutex{}
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}
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return km.mutexMap[id]
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}
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