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58 lines
1.5 KiB
58 lines
1.5 KiB
/* |
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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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) |
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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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km.mutexes[km.hash(id)%uint32(len(km.mutexes))].Lock() |
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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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km.mutexes[km.hash(id)%uint32(len(km.mutexes))].Unlock() |
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return nil |
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} |
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func (km *hashedKeyMutex) hash(id string) uint32 { |
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h := fnv.New32a() |
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h.Write([]byte(id)) |
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return h.Sum32() |
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}
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