naiveproxy/base/task_scheduler/lazy_task_runner.cc
2018-02-02 05:49:39 -05:00

117 lines
3.8 KiB
C++

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