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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 #include "base/sequence_checker_impl.h"
6 
7 namespace base {
8 
SequenceCheckerImpl()9 SequenceCheckerImpl::SequenceCheckerImpl()
10     : sequence_token_assigned_(false) {
11   AutoLock auto_lock(lock_);
12   EnsureSequenceTokenAssigned();
13 }
14 
~SequenceCheckerImpl()15 SequenceCheckerImpl::~SequenceCheckerImpl() {}
16 
CalledOnValidSequencedThread() const17 bool SequenceCheckerImpl::CalledOnValidSequencedThread() const {
18   AutoLock auto_lock(lock_);
19   EnsureSequenceTokenAssigned();
20 
21   // If this thread is not associated with a SequencedWorkerPool,
22   // SequenceChecker behaves as a ThreadChecker. See header for details.
23   if (!sequence_token_.IsValid())
24     return thread_checker_.CalledOnValidThread();
25 
26   return sequence_token_.Equals(
27       SequencedWorkerPool::GetSequenceTokenForCurrentThread());
28 }
29 
DetachFromSequence()30 void SequenceCheckerImpl::DetachFromSequence() {
31   AutoLock auto_lock(lock_);
32   thread_checker_.DetachFromThread();
33   sequence_token_assigned_ = false;
34   sequence_token_ = SequencedWorkerPool::SequenceToken();
35 }
36 
EnsureSequenceTokenAssigned() const37 void SequenceCheckerImpl::EnsureSequenceTokenAssigned() const {
38   lock_.AssertAcquired();
39   if (sequence_token_assigned_)
40     return;
41 
42   sequence_token_assigned_ = true;
43   sequence_token_ = SequencedWorkerPool::GetSequenceTokenForCurrentThread();
44 }
45 
46 }  // namespace base
47