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