base/sequence_token.cc

   1 // Copyright 2016 The Chromium Authors
   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_token.h"
   6
   7 #include "base/atomic_sequence_num.h"
   8 #include "third_party/abseil-cpp/absl/base/attributes.h"
   9
  10 namespace base {
  11
  12 namespace {
  13
  14 base::AtomicSequenceNumber g_sequence_token_generator;
  15
  16 base::AtomicSequenceNumber g_task_token_generator;
  17
  18 ABSL_CONST_INIT thread_local SequenceToken current_sequence_token;
  19 ABSL_CONST_INIT thread_local TaskToken current_task_token;
  20
  21 }  // namespace
  22
  23 bool SequenceToken::operator==(const SequenceToken& other) const {
  24   return token_ == other.token_ && IsValid();
  25 }
  26
  27 bool SequenceToken::operator!=(const SequenceToken& other) const {
  28   return !(*this == other);
  29 }
  30
  31 bool SequenceToken::IsValid() const {
  32   return token_ != kInvalidSequenceToken;
  33 }
  34
  35 int SequenceToken::ToInternalValue() const {
  36   return token_;
  37 }
  38
  39 SequenceToken SequenceToken::Create() {
  40   return SequenceToken(g_sequence_token_generator.GetNext());
  41 }
  42
  43 SequenceToken SequenceToken::GetForCurrentThread() {
  44   return current_sequence_token;
  45 }
  46
  47 bool TaskToken::operator==(const TaskToken& other) const {
  48   return token_ == other.token_ && IsValid();
  49 }
  50
  51 bool TaskToken::operator!=(const TaskToken& other) const {
  52   return !(*this == other);
  53 }
  54
  55 bool TaskToken::IsValid() const {
  56   return token_ != kInvalidTaskToken;
  57 }
  58
  59 TaskToken TaskToken::Create() {
  60   return TaskToken(g_task_token_generator.GetNext());
  61 }
  62
  63 TaskToken TaskToken::GetForCurrentThread() {
  64   return current_task_token;
  65 }
  66
  67 ScopedSetSequenceTokenForCurrentThread::ScopedSetSequenceTokenForCurrentThread(
  68     const SequenceToken& sequence_token)
  69     // The lambdas here exist because invalid tokens don't compare equal, so
  70     // passing invalid sequence/task tokens as the third args to AutoReset
  71     // constructors doesn't work.
  72     : sequence_token_resetter_(&current_sequence_token,
  73                                [&sequence_token]() {
  74                                  DCHECK(!current_sequence_token.IsValid());
  75                                  return sequence_token;
  76                                }()),
  77       task_token_resetter_(&current_task_token, [] {
  78         DCHECK(!current_task_token.IsValid());
  79         return TaskToken::Create();
  80       }()) {}
  81
  82 ScopedSetSequenceTokenForCurrentThread::
  83     ~ScopedSetSequenceTokenForCurrentThread() = default;
  84
  85 }  // namespace base