// Copyright 2017 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/task_scheduler/lazy_task_runner.h"
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#include <utility>
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#include "base/lazy_instance.h"
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#include "base/logging.h"
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#include "base/task_scheduler/post_task.h"
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namespace base {
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namespace internal {
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namespace {
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ScopedLazyTaskRunnerListForTesting* g_scoped_lazy_task_runner_list_for_testing =
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nullptr;
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} // namespace
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template <typename TaskRunnerType, bool com_sta>
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void LazyTaskRunner<TaskRunnerType, com_sta>::Reset() {
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subtle::AtomicWord state = subtle::Acquire_Load(&state_);
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DCHECK_NE(state, kLazyInstanceStateCreating) << "Race: all threads should be "
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"unwound in unittests before "
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"resetting TaskRunners.";
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// Return if no reference is held by this instance.
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if (!state)
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return;
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// Release the reference acquired in Get().
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SequencedTaskRunner* task_runner = reinterpret_cast<TaskRunnerType*>(state);
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task_runner->Release();
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// Clear the state.
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subtle::NoBarrier_Store(&state_, 0);
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}
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template <>
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scoped_refptr<SequencedTaskRunner>
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LazyTaskRunner<SequencedTaskRunner, false>::Create() {
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// It is invalid to specify a SingleThreadTaskRunnerThreadMode with a
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// LazySequencedTaskRunner.
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DCHECK_EQ(thread_mode_, SingleThreadTaskRunnerThreadMode::SHARED);
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return CreateSequencedTaskRunnerWithTraits(traits_);
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}
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template <>
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scoped_refptr<SingleThreadTaskRunner>
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LazyTaskRunner<SingleThreadTaskRunner, false>::Create() {
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return CreateSingleThreadTaskRunnerWithTraits(traits_, thread_mode_);
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}
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#if defined(OS_WIN)
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template <>
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scoped_refptr<SingleThreadTaskRunner>
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LazyTaskRunner<SingleThreadTaskRunner, true>::Create() {
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return CreateCOMSTATaskRunnerWithTraits(traits_, thread_mode_);
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}
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#endif
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// static
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template <typename TaskRunnerType, bool com_sta>
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TaskRunnerType* LazyTaskRunner<TaskRunnerType, com_sta>::CreateRaw(
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void* void_self) {
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auto self =
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reinterpret_cast<LazyTaskRunner<TaskRunnerType, com_sta>*>(void_self);
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scoped_refptr<TaskRunnerType> task_runner = self->Create();
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// Acquire a reference to the TaskRunner. The reference will either
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// never be released or be released in Reset(). The reference is not
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// managed by a scoped_refptr because adding a scoped_refptr member to
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// LazyTaskRunner would prevent its static initialization.
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task_runner->AddRef();
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// Reset this instance when the current
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// ScopedLazyTaskRunnerListForTesting is destroyed, if any.
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if (g_scoped_lazy_task_runner_list_for_testing) {
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g_scoped_lazy_task_runner_list_for_testing->AddCallback(BindOnce(
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&LazyTaskRunner<TaskRunnerType, com_sta>::Reset, Unretained(self)));
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}
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return task_runner.get();
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}
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template <typename TaskRunnerType, bool com_sta>
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scoped_refptr<TaskRunnerType> LazyTaskRunner<TaskRunnerType, com_sta>::Get() {
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return WrapRefCounted(subtle::GetOrCreateLazyPointer(
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&state_, &LazyTaskRunner<TaskRunnerType, com_sta>::CreateRaw,
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reinterpret_cast<void*>(this), nullptr, nullptr));
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}
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template class LazyTaskRunner<SequencedTaskRunner, false>;
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template class LazyTaskRunner<SingleThreadTaskRunner, false>;
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#if defined(OS_WIN)
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template class LazyTaskRunner<SingleThreadTaskRunner, true>;
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#endif
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ScopedLazyTaskRunnerListForTesting::ScopedLazyTaskRunnerListForTesting() {
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DCHECK(!g_scoped_lazy_task_runner_list_for_testing);
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g_scoped_lazy_task_runner_list_for_testing = this;
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}
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ScopedLazyTaskRunnerListForTesting::~ScopedLazyTaskRunnerListForTesting() {
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internal::AutoSchedulerLock auto_lock(lock_);
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for (auto& callback : callbacks_)
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std::move(callback).Run();
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g_scoped_lazy_task_runner_list_for_testing = nullptr;
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}
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void ScopedLazyTaskRunnerListForTesting::AddCallback(OnceClosure callback) {
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internal::AutoSchedulerLock auto_lock(lock_);
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callbacks_.push_back(std::move(callback));
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}
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} // namespace internal
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} // namespace base
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