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// Copyright 2013, Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package sync2
import (
"sync"
)
// Cond is an alternate implementation of sync.Cond
type Cond struct {
L sync.Locker
sema chan struct{}
waiters AtomicInt64
}
func NewCond(l sync.Locker) *Cond {
return &Cond{L: l, sema: make(chan struct{})}
}
func (c *Cond) Wait() {
c.waiters.Add(1)
c.L.Unlock()
<-c.sema
c.L.Lock()
}
func (c *Cond) Signal() {
for {
w := c.waiters.Get()
if w == 0 {
return
}
if c.waiters.CompareAndSwap(w, w-1) {
break
}
}
c.sema <- struct{}{}
}
func (c *Cond) Broadcast() {
var w int64
for {
w = c.waiters.Get()
if w == 0 {
return
}
if c.waiters.CompareAndSwap(w, 0) {
break
}
}
for i := int64(0); i < w; i++ {
c.sema <- struct{}{}
}
}
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