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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_SYNCHRONIZATION_CANCELLATION_FLAG_H_
#define BASE_SYNCHRONIZATION_CANCELLATION_FLAG_H_
#include "base/atomicops.h"
#include "base/base_export.h"
#include "base/macros.h"
#include "base/threading/platform_thread.h"
namespace base {
// CancellationFlag allows one thread to cancel jobs executed on some worker
// thread. Calling Set() from one thread and IsSet() from a number of threads
// is thread-safe.
//
// This class IS NOT intended for synchronization between threads.
class BASE_EXPORT CancellationFlag {
public:
CancellationFlag() : flag_(false) {
#if !defined(NDEBUG)
set_on_ = PlatformThread::CurrentId();
#endif
}
~CancellationFlag() {}
// Set the flag. May only be called on the thread which owns the object.
void Set();
bool IsSet() const; // Returns true iff the flag was set.
// For subtle reasons that may be different on different architectures,
// a different thread testing IsSet() may erroneously read 'true' after
// this method has been called.
void UnsafeResetForTesting();
private:
base::subtle::Atomic32 flag_;
#if !defined(NDEBUG)
PlatformThreadId set_on_;
#endif
DISALLOW_COPY_AND_ASSIGN(CancellationFlag);
};
} // namespace base
#endif // BASE_SYNCHRONIZATION_CANCELLATION_FLAG_H_
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