base/sequence_token.cc

   1 // Copyright 2016 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_token.h"
   6
   7 #include "base/atomic_sequence_num.h"
   8 #include "base/check_op.h"
   9 #include "base/no_destructor.h"
  10 #include "base/threading/thread_local.h"
  11
  12 namespace base {
  13
  14 namespace {
  15
  16 base::AtomicSequenceNumber g_sequence_token_generator;
  17
  18 base::AtomicSequenceNumber g_task_token_generator;
  19
  20 ThreadLocalPointer<const SequenceToken>& GetTlsCurrentSequenceToken() {
  21   static base::NoDestructor<ThreadLocalPointer<const SequenceToken>> instance;
  22   return *instance;
  23 }
  24
  25 ThreadLocalPointer<const TaskToken>& GetTlsCurrentTaskToken() {
  26   static base::NoDestructor<ThreadLocalPointer<const TaskToken>> instance;
  27   return *instance;
  28 }
  29
  30 }  // namespace
  31
  32 bool SequenceToken::operator==(const SequenceToken& other) const {
  33   return token_ == other.token_ && IsValid();
  34 }
  35
  36 bool SequenceToken::operator!=(const SequenceToken& other) const {
  37   return !(*this == other);
  38 }
  39
  40 bool SequenceToken::IsValid() const {
  41   return token_ != kInvalidSequenceToken;
  42 }
  43
  44 int SequenceToken::ToInternalValue() const {
  45   return token_;
  46 }
  47
  48 SequenceToken SequenceToken::Create() {
  49   return SequenceToken(g_sequence_token_generator.GetNext());
  50 }
  51
  52 SequenceToken SequenceToken::GetForCurrentThread() {
  53   const SequenceToken* current_sequence_token =
  54       GetTlsCurrentSequenceToken().Get();
  55   return current_sequence_token ? *current_sequence_token : SequenceToken();
  56 }
  57
  58 bool TaskToken::operator==(const TaskToken& other) const {
  59   return token_ == other.token_ && IsValid();
  60 }
  61
  62 bool TaskToken::operator!=(const TaskToken& other) const {
  63   return !(*this == other);
  64 }
  65
  66 bool TaskToken::IsValid() const {
  67   return token_ != kInvalidTaskToken;
  68 }
  69
  70 TaskToken TaskToken::Create() {
  71   return TaskToken(g_task_token_generator.GetNext());
  72 }
  73
  74 TaskToken TaskToken::GetForCurrentThread() {
  75   const TaskToken* current_task_token = GetTlsCurrentTaskToken().Get();
  76   return current_task_token ? *current_task_token : TaskToken();
  77 }
  78
  79 ScopedSetSequenceTokenForCurrentThread::ScopedSetSequenceTokenForCurrentThread(
  80     const SequenceToken& sequence_token)
  81     : sequence_token_(sequence_token), task_token_(TaskToken::Create()) {
  82   DCHECK(!GetTlsCurrentSequenceToken().Get());
  83   DCHECK(!GetTlsCurrentTaskToken().Get());
  84   GetTlsCurrentSequenceToken().Set(&sequence_token_);
  85   GetTlsCurrentTaskToken().Set(&task_token_);
  86 }
  87
  88 ScopedSetSequenceTokenForCurrentThread::
  89     ~ScopedSetSequenceTokenForCurrentThread() {
  90   DCHECK_EQ(GetTlsCurrentSequenceToken().Get(), &sequence_token_);
  91   DCHECK_EQ(GetTlsCurrentTaskToken().Get(), &task_token_);
  92   GetTlsCurrentSequenceToken().Set(nullptr);
  93   GetTlsCurrentTaskToken().Set(nullptr);
  94 }
  95
  96 }  // namespace base