michael@0: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #ifndef BASE_SEQUENCE_CHECKER_IMPL_H_
michael@0: #define BASE_SEQUENCE_CHECKER_IMPL_H_
michael@0: 
michael@0: #include "base/base_export.h"
michael@0: #include "base/basictypes.h"
michael@0: #include "base/synchronization/lock.h"
michael@0: #include "base/threading/sequenced_worker_pool.h"
michael@0: #include "base/threading/thread_checker_impl.h"
michael@0: 
michael@0: namespace base {
michael@0: 
michael@0: // SequenceCheckerImpl is used to help verify that some methods of a
michael@0: // class are called in sequence -- that is, called from the same
michael@0: // SequencedTaskRunner. It is a generalization of ThreadChecker; in
michael@0: // particular, it behaves exactly like ThreadChecker if constructed
michael@0: // on a thread that is not part of a SequencedWorkerPool.
michael@0: class BASE_EXPORT SequenceCheckerImpl {
michael@0:  public:
michael@0:   SequenceCheckerImpl();
michael@0:   ~SequenceCheckerImpl();
michael@0: 
michael@0:   // Returns whether the we are being called on the same sequence token
michael@0:   // as previous calls. If there is no associated sequence, then returns
michael@0:   // whether we are being called on the underlying ThreadChecker's thread.
michael@0:   bool CalledOnValidSequencedThread() const;
michael@0: 
michael@0:   // Unbinds the checker from the currently associated sequence. The
michael@0:   // checker will be re-bound on the next call to CalledOnValidSequence().
michael@0:   void DetachFromSequence();
michael@0: 
michael@0:  private:
michael@0:   void EnsureSequenceTokenAssigned() const;
michael@0: 
michael@0:   // Guards all variables below.
michael@0:   mutable Lock lock_;
michael@0: 
michael@0:   // Used if |sequence_token_| is not valid.
michael@0:   ThreadCheckerImpl thread_checker_;
michael@0:   mutable bool sequence_token_assigned_;
michael@0: 
michael@0:   mutable SequencedWorkerPool::SequenceToken sequence_token_;
michael@0: 
michael@0:   DISALLOW_COPY_AND_ASSIGN(SequenceCheckerImpl);
michael@0: };
michael@0: 
michael@0: }  // namespace base
michael@0: 
michael@0: #endif  // BASE_SEQUENCE_CHECKER_IMPL_H_