sequenced_task_runner_handle.cc 1.6 KB

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  1. // Copyright 2015 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. #include "base/threading/sequenced_task_runner_handle.h"
  5. #include <utility>
  6. #include "base/check_op.h"
  7. #include "base/lazy_instance.h"
  8. #include "base/threading/thread_local.h"
  9. namespace base {
  10. namespace {
  11. LazyInstance<ThreadLocalPointer<SequencedTaskRunnerHandle>>::Leaky
  12. sequenced_task_runner_tls = LAZY_INSTANCE_INITIALIZER;
  13. } // namespace
  14. // static
  15. const scoped_refptr<SequencedTaskRunner>& SequencedTaskRunnerHandle::Get() {
  16. const SequencedTaskRunnerHandle* current =
  17. sequenced_task_runner_tls.Pointer()->Get();
  18. CHECK(current)
  19. << "Error: This caller requires a sequenced context (i.e. the current "
  20. "task needs to run from a SequencedTaskRunner). If you're in a test "
  21. "refer to //docs/threading_and_tasks_testing.md.";
  22. return current->task_runner_;
  23. }
  24. // static
  25. bool SequencedTaskRunnerHandle::IsSet() {
  26. return !!sequenced_task_runner_tls.Pointer()->Get();
  27. }
  28. SequencedTaskRunnerHandle::SequencedTaskRunnerHandle(
  29. scoped_refptr<SequencedTaskRunner> task_runner)
  30. : task_runner_(std::move(task_runner)) {
  31. DCHECK(task_runner_->RunsTasksInCurrentSequence());
  32. DCHECK(!SequencedTaskRunnerHandle::IsSet());
  33. sequenced_task_runner_tls.Pointer()->Set(this);
  34. }
  35. SequencedTaskRunnerHandle::~SequencedTaskRunnerHandle() {
  36. DCHECK(task_runner_->RunsTasksInCurrentSequence());
  37. DCHECK_EQ(sequenced_task_runner_tls.Pointer()->Get(), this);
  38. sequenced_task_runner_tls.Pointer()->Set(nullptr);
  39. }
  40. } // namespace base