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// Copyright 2019 The gVisor Authors.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build go1.13
// +build !go1.15
// When updating the build constraint (above), check that syncMutex matches the
// standard library sync.Mutex definition.
package sync
import (
"sync"
"sync/atomic"
"unsafe"
)
// Mutex is a try lock.
type Mutex struct {
sync.Mutex
}
type syncMutex struct {
state int32
sema uint32
}
func (m *Mutex) state() *int32 {
return &(*syncMutex)(unsafe.Pointer(&m.Mutex)).state
}
const (
mutexUnlocked = 0
mutexLocked = 1
)
// TryLock tries to aquire the mutex. It returns true if it succeeds and false
// otherwise. TryLock does not block.
func (m *Mutex) TryLock() bool {
if atomic.CompareAndSwapInt32(m.state(), mutexUnlocked, mutexLocked) {
if RaceEnabled {
RaceAcquire(unsafe.Pointer(&m.Mutex))
}
return true
}
return false
}
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