From 30388ff5919df33e7184719dfc6c0d9cb110b2e2 Mon Sep 17 00:00:00 2001 From: Jamie Liu Date: Thu, 2 Apr 2020 11:55:55 -0700 Subject: Rename files in //pkg/sync to better reflect what they contain. PiperOrigin-RevId: 304447031 --- pkg/sync/mutex_unsafe.go | 49 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 pkg/sync/mutex_unsafe.go (limited to 'pkg/sync/mutex_unsafe.go') diff --git a/pkg/sync/mutex_unsafe.go b/pkg/sync/mutex_unsafe.go new file mode 100644 index 000000000..3dd15578b --- /dev/null +++ b/pkg/sync/mutex_unsafe.go @@ -0,0 +1,49 @@ +// 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 +} -- cgit v1.2.3