1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef BASE_SYNCHRONIZATION_CANCELLATION_FLAG_H_
6#define BASE_SYNCHRONIZATION_CANCELLATION_FLAG_H_
7#pragma once
8
9#include "base/base_api.h"
10#include "base/atomicops.h"
11#include "base/threading/platform_thread.h"
12
13namespace base {
14
15// CancellationFlag allows one thread to cancel jobs executed on some worker
16// thread. Calling Set() from one thread and IsSet() from a number of threads
17// is thread-safe.
18//
19// This class IS NOT intended for synchronization between threads.
20class BASE_API CancellationFlag {
21 public:
22  CancellationFlag() : flag_(false) {
23#if !defined(NDEBUG)
24    set_on_ = PlatformThread::CurrentId();
25#endif
26  }
27  ~CancellationFlag() {}
28
29  // Set the flag. May only be called on the thread which owns the object.
30  void Set();
31  bool IsSet() const;  // Returns true iff the flag was set.
32
33 private:
34  base::subtle::Atomic32 flag_;
35#if !defined(NDEBUG)
36  PlatformThreadId set_on_;
37#endif
38
39  DISALLOW_COPY_AND_ASSIGN(CancellationFlag);
40};
41
42}  // namespace base
43
44#endif  // BASE_SYNCHRONIZATION_CANCELLATION_FLAG_H_
45