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37 lines
718 B
Go
37 lines
718 B
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package ws
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import (
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"sync"
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"sync/atomic"
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)
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// Modified version of sync.Once (https://github.com/golang/go/blob/master/src/sync/once.go)
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// This version unlocks the mutex early and therefore doesn't hold the lock while executing func f().
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type once struct {
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m sync.Mutex
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done uint32
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}
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func (o *once) Do(f func()) {
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if atomic.LoadUint32(&o.done) == 1 {
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return
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}
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if o.mayExecute() {
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f()
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}
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}
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func (o *once) mayExecute() bool {
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o.m.Lock()
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defer o.m.Unlock()
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if o.done == 0 {
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atomic.StoreUint32(&o.done, 1)
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return true
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}
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return false
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}
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