Roll src/third_party/WebKit 1dfb44f:c96f7be (svn 183545:183546)
[chromium-blink-merge.git] / base / sequence_checker_impl.h
blob741aafee645946791a95515cad1d1833f10aaec8
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.
5 #ifndef BASE_SEQUENCE_CHECKER_IMPL_H_
6 #define BASE_SEQUENCE_CHECKER_IMPL_H_
8 #include "base/base_export.h"
9 #include "base/basictypes.h"
10 #include "base/synchronization/lock.h"
11 #include "base/threading/sequenced_worker_pool.h"
12 #include "base/threading/thread_checker_impl.h"
14 namespace base {
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();
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;
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();
35 private:
36 void EnsureSequenceTokenAssigned() const;
38 // Guards all variables below.
39 mutable Lock lock_;
41 // Used if |sequence_token_| is not valid.
42 ThreadCheckerImpl thread_checker_;
43 mutable bool sequence_token_assigned_;
45 mutable SequencedWorkerPool::SequenceToken sequence_token_;
47 DISALLOW_COPY_AND_ASSIGN(SequenceCheckerImpl);
50 } // namespace base
52 #endif // BASE_SEQUENCE_CHECKER_IMPL_H_