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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 #include "base/logging.h"
8 #include "base/memory/ptr_util.h"
9 #include "base/sequence_token.h"
10 #include "base/threading/thread_checker_impl.h"
11 
12 namespace base {
13 
14 class SequenceCheckerImpl::Core {
15  public:
Core()16   Core() : sequence_token_(SequenceToken::GetForCurrentThread()) {}
17 
18   ~Core() = default;
19 
CalledOnValidSequence() const20   bool CalledOnValidSequence() const {
21     if (sequence_token_.IsValid())
22       return sequence_token_ == SequenceToken::GetForCurrentThread();
23 
24     // SequenceChecker behaves as a ThreadChecker when it is not bound to a
25     // valid sequence token.
26     return thread_checker_.CalledOnValidThread();
27   }
28 
29  private:
30   SequenceToken sequence_token_;
31 
32   // Used when |sequence_token_| is invalid.
33   ThreadCheckerImpl thread_checker_;
34 };
35 
SequenceCheckerImpl()36 SequenceCheckerImpl::SequenceCheckerImpl() : core_(std::make_unique<Core>()) {}
37 SequenceCheckerImpl::~SequenceCheckerImpl() = default;
38 
CalledOnValidSequence() const39 bool SequenceCheckerImpl::CalledOnValidSequence() const {
40   AutoLock auto_lock(lock_);
41   if (!core_)
42     core_ = std::make_unique<Core>();
43   return core_->CalledOnValidSequence();
44 }
45 
DetachFromSequence()46 void SequenceCheckerImpl::DetachFromSequence() {
47   AutoLock auto_lock(lock_);
48   core_.reset();
49 }
50 
51 }  // namespace base
52