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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/task/lazy_thread_pool_task_runner.h"
#include <atomic>
#include <utility>
#include "base/check_op.h"
#include "base/lazy_instance_helpers.h"
#include "base/task/thread_pool.h"
#include "build/build_config.h"
namespace base {
namespace internal {
namespace {
ScopedLazyTaskRunnerListForTesting* g_scoped_lazy_task_runner_list_for_testing =
nullptr;
} // namespace
template <typename TaskRunnerType, bool com_sta>
void LazyThreadPoolTaskRunner<TaskRunnerType, com_sta>::Reset() {
uintptr_t state = state_.load(std::memory_order_acquire);
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.
state_.store(0, std::memory_order_relaxed);
}
template <>
scoped_refptr<SequencedTaskRunner>
LazyThreadPoolTaskRunner<SequencedTaskRunner, false>::Create() {
// It is invalid to specify a SingleThreadTaskRunnerThreadMode with a
// LazyThreadPoolSequencedTaskRunner.
DCHECK_EQ(thread_mode_, SingleThreadTaskRunnerThreadMode::SHARED);
return ThreadPool::CreateSequencedTaskRunner(traits_);
}
template <>
scoped_refptr<SingleThreadTaskRunner>
LazyThreadPoolTaskRunner<SingleThreadTaskRunner, false>::Create() {
return ThreadPool::CreateSingleThreadTaskRunner(traits_, thread_mode_);
}
#if BUILDFLAG(IS_WIN)
template <>
scoped_refptr<SingleThreadTaskRunner>
LazyThreadPoolTaskRunner<SingleThreadTaskRunner, true>::Create() {
return ThreadPool::CreateCOMSTATaskRunner(traits_, thread_mode_);
}
#endif
// static
template <typename TaskRunnerType, bool com_sta>
TaskRunnerType* LazyThreadPoolTaskRunner<TaskRunnerType, com_sta>::CreateRaw(
void* void_self) {
auto self =
reinterpret_cast<LazyThreadPoolTaskRunner<TaskRunnerType, com_sta>*>(
void_self);
scoped_refptr<TaskRunnerType> task_runner = self->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
// LazyThreadPoolTaskRunner 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(&LazyThreadPoolTaskRunner<TaskRunnerType, com_sta>::Reset,
Unretained(self)));
}
return task_runner.get();
}
template <typename TaskRunnerType, bool com_sta>
scoped_refptr<TaskRunnerType>
LazyThreadPoolTaskRunner<TaskRunnerType, com_sta>::Get() {
return WrapRefCounted(subtle::GetOrCreateLazyPointer(
state_, &LazyThreadPoolTaskRunner<TaskRunnerType, com_sta>::CreateRaw,
reinterpret_cast<void*>(this), nullptr, nullptr));
}
template class LazyThreadPoolTaskRunner<SequencedTaskRunner, false>;
template class LazyThreadPoolTaskRunner<SingleThreadTaskRunner, false>;
#if BUILDFLAG(IS_WIN)
template class LazyThreadPoolTaskRunner<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::CheckedAutoLock 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::CheckedAutoLock auto_lock(lock_);
callbacks_.push_back(std::move(callback));
}
} // namespace internal
} // namespace base
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