1 // Copyright (c) 2012 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_SEQUENCE_CHECKER_IMPL_H_ 6 #define BASE_SEQUENCE_CHECKER_IMPL_H_ 7 8 #include "base/base_export.h" 9 #include "base/macros.h" 10 #include "base/synchronization/lock.h" 11 #include "base/threading/sequenced_worker_pool.h" 12 #include "base/threading/thread_checker_impl.h" 13 14 namespace base { 15 16 // SequenceCheckerImpl is used to help verify that some methods of a 17 // class are called in sequence -- that is, called from the same 18 // SequencedTaskRunner. It is a generalization of ThreadChecker; in 19 // particular, it behaves exactly like ThreadChecker if constructed 20 // on a thread that is not part of a SequencedWorkerPool. 21 class BASE_EXPORT SequenceCheckerImpl { 22 public: 23 SequenceCheckerImpl(); 24 ~SequenceCheckerImpl(); 25 26 // Returns whether the we are being called on the same sequence token 27 // as previous calls. If there is no associated sequence, then returns 28 // whether we are being called on the underlying ThreadChecker's thread. 29 bool CalledOnValidSequencedThread() const; 30 31 // Unbinds the checker from the currently associated sequence. The 32 // checker will be re-bound on the next call to CalledOnValidSequence(). 33 void DetachFromSequence(); 34 35 private: 36 void EnsureSequenceTokenAssigned() const; 37 38 // Guards all variables below. 39 mutable Lock lock_; 40 41 // Used if |sequence_token_| is not valid. 42 ThreadCheckerImpl thread_checker_; 43 mutable bool sequence_token_assigned_; 44 45 mutable SequencedWorkerPool::SequenceToken sequence_token_; 46 47 DISALLOW_COPY_AND_ASSIGN(SequenceCheckerImpl); 48 }; 49 50 } // namespace base 51 52 #endif // BASE_SEQUENCE_CHECKER_IMPL_H_ 53