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Name	Size	Permission
atomic	[ DIR ]	drwxr-xr-x
cond.go	2.54 KB	-rw-r--r--
cond_test.go	5.07 KB	-rw-r--r--
example_pool_test.go	1 KB	-rw-r--r--
example_test.go	1.14 KB	-rw-r--r--
export_test.go	1.27 KB	-rw-r--r--
map.go	11 KB	-rw-r--r--
map_bench_test.go	4.79 KB	-rw-r--r--
map_reference_test.go	3.39 KB	-rw-r--r--
map_test.go	3.45 KB	-rw-r--r--
mutex.go	7.32 KB	-rw-r--r--
mutex_test.go	5.7 KB	-rw-r--r--
once.go	2.25 KB	-rw-r--r--
once_test.go	1.1 KB	-rw-r--r--
pool.go	8.15 KB	-rw-r--r--
pool_test.go	7.25 KB	-rw-r--r--
poolqueue.go	8.87 KB	-rw-r--r--
runtime.go	2.17 KB	-rw-r--r--
runtime_sema_test.go	1.34 KB	-rw-r--r--
rwmutex.go	4.42 KB	-rw-r--r--
rwmutex_test.go	4.36 KB	-rw-r--r--
waitgroup.go	4.41 KB	-rw-r--r--
waitgroup_test.go	5.78 KB	-rw-r--r--

Code Editor : cond.go

// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sync

import (
	"sync/atomic"
	"unsafe"
)

// Cond implements a condition variable, a rendezvous point
// for goroutines waiting for or announcing the occurrence
// of an event.
//
// Each Cond has an associated Locker L (often a *Mutex or *RWMutex),
// which must be held when changing the condition and
// when calling the Wait method.
//
// A Cond must not be copied after first use.
type Cond struct {
	noCopy noCopy

// L is held while observing or changing the condition
	L Locker

notify  notifyList
	checker copyChecker
}

// NewCond returns a new Cond with Locker l.
func NewCond(l Locker) *Cond {
	return &Cond{L: l}
}

// Wait atomically unlocks c.L and suspends execution
// of the calling goroutine. After later resuming execution,
// Wait locks c.L before returning. Unlike in other systems,
// Wait cannot return unless awoken by Broadcast or Signal.
//
// Because c.L is not locked when Wait first resumes, the caller
// typically cannot assume that the condition is true when
// Wait returns. Instead, the caller should Wait in a loop:
//
//    c.L.Lock()
//    for !condition() {
//        c.Wait()
//    }
//    ... make use of condition ...
//    c.L.Unlock()
//
func (c *Cond) Wait() {
	c.checker.check()
	t := runtime_notifyListAdd(&c.notify)
	c.L.Unlock()
	runtime_notifyListWait(&c.notify, t)
	c.L.Lock()
}

// Signal wakes one goroutine waiting on c, if there is any.
//
// It is allowed but not required for the caller to hold c.L
// during the call.
func (c *Cond) Signal() {
	c.checker.check()
	runtime_notifyListNotifyOne(&c.notify)
}

// Broadcast wakes all goroutines waiting on c.
//
// It is allowed but not required for the caller to hold c.L
// during the call.
func (c *Cond) Broadcast() {
	c.checker.check()
	runtime_notifyListNotifyAll(&c.notify)
}

// copyChecker holds back pointer to itself to detect object copying.
type copyChecker uintptr

func (c *copyChecker) check() {
	if uintptr(*c) != uintptr(unsafe.Pointer(c)) &&
		!atomic.CompareAndSwapUintptr((*uintptr)(c), 0, uintptr(unsafe.Pointer(c))) &&
		uintptr(*c) != uintptr(unsafe.Pointer(c)) {
		panic("sync.Cond is copied")
	}
}

// noCopy may be embedded into structs which must not be copied
// after the first use.
//
// See https://golang.org/issues/8005#issuecomment-190753527
// for details.
type noCopy struct{}

// Lock is a no-op used by -copylocks checker from `go vet`.
func (*noCopy) Lock()   {}
func (*noCopy) Unlock() {}

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Code Editor : cond.go