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// Copyright (c) 2012 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_SEQUENCE_CHECKER_IMPL_H_
#define BASE_SEQUENCE_CHECKER_IMPL_H_
#include "base/base_export.h"
#include "base/basictypes.h"
#include "base/synchronization/lock.h"
#include "base/threading/sequenced_worker_pool.h"
#include "base/threading/thread_checker_impl.h"
namespace base {
// SequenceCheckerImpl is used to help verify that some methods of a
// class are called in sequence -- that is, called from the same
// SequencedTaskRunner. It is a generalization of ThreadChecker; in
// particular, it behaves exactly like ThreadChecker if constructed
// on a thread that is not part of a SequencedWorkerPool.
class BASE_EXPORT SequenceCheckerImpl {
public:
SequenceCheckerImpl();
~SequenceCheckerImpl();
// Returns whether the we are being called on the same sequence token
// as previous calls. If there is no associated sequence, then returns
// whether we are being called on the underlying ThreadChecker's thread.
bool CalledOnValidSequencedThread() const;
// Unbinds the checker from the currently associated sequence. The
// checker will be re-bound on the next call to CalledOnValidSequence().
void DetachFromSequence();
private:
void EnsureSequenceTokenAssigned() const;
// Guards all variables below.
mutable Lock lock_;
// Used if |sequence_token_| is not valid.
ThreadCheckerImpl thread_checker_;
mutable bool sequence_token_assigned_;
mutable SequencedWorkerPool::SequenceToken sequence_token_;
DISALLOW_COPY_AND_ASSIGN(SequenceCheckerImpl);
};
} // namespace base
#endif // BASE_SEQUENCE_CHECKER_IMPL_H_
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