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- // Copyright 2013 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/one_shot_event.h"
- #include <stddef.h>
- #include <utility>
- #include "base/callback.h"
- #include "base/location.h"
- #include "base/task/single_thread_task_runner.h"
- #include "base/task/task_runner.h"
- #include "base/threading/thread_task_runner_handle.h"
- #include "base/time/time.h"
- namespace base {
- struct OneShotEvent::TaskInfo {
- TaskInfo() {}
- TaskInfo(const Location& from_here,
- scoped_refptr<SingleThreadTaskRunner> runner,
- OnceClosure task,
- const TimeDelta& delay)
- : from_here(from_here),
- runner(std::move(runner)),
- task(std::move(task)),
- delay(delay) {
- CHECK(this->runner.get()); // Detect mistakes with a decent stack frame.
- }
- TaskInfo(TaskInfo&&) = default;
- TaskInfo& operator=(TaskInfo&&) = default;
- Location from_here;
- scoped_refptr<SingleThreadTaskRunner> runner;
- OnceClosure task;
- TimeDelta delay;
- };
- OneShotEvent::OneShotEvent() : signaled_(false) {
- // It's acceptable to construct the OneShotEvent on one thread, but
- // immediately move it to another thread.
- thread_checker_.DetachFromThread();
- }
- OneShotEvent::OneShotEvent(bool signaled) : signaled_(signaled) {
- thread_checker_.DetachFromThread();
- }
- OneShotEvent::~OneShotEvent() {}
- void OneShotEvent::Post(const Location& from_here,
- OnceClosure task,
- scoped_refptr<SingleThreadTaskRunner> runner) const {
- PostImpl(from_here, std::move(task), std::move(runner), TimeDelta());
- }
- void OneShotEvent::PostDelayed(const Location& from_here,
- OnceClosure task,
- const TimeDelta& delay) const {
- PostImpl(from_here, std::move(task), ThreadTaskRunnerHandle::Get(), delay);
- }
- void OneShotEvent::Signal() {
- DCHECK(thread_checker_.CalledOnValidThread());
- CHECK(!signaled_) << "Only call Signal once.";
- signaled_ = true;
- // After this point, a call to Post() from one of the queued tasks
- // could proceed immediately, but the fact that this object is
- // single-threaded prevents that from being relevant.
- // Move tasks to a temporary to ensure no new ones are added.
- std::vector<TaskInfo> moved_tasks;
- std::swap(moved_tasks, tasks_);
- // We could randomize tasks in debug mode in order to check that
- // the order doesn't matter...
- for (TaskInfo& task : moved_tasks) {
- if (task.delay.is_zero())
- task.runner->PostTask(task.from_here, std::move(task.task));
- else
- task.runner->PostDelayedTask(task.from_here, std::move(task.task),
- task.delay);
- }
- DCHECK(tasks_.empty()) << "No new tasks should be added during task running!";
- }
- void OneShotEvent::PostImpl(const Location& from_here,
- OnceClosure task,
- scoped_refptr<SingleThreadTaskRunner> runner,
- const TimeDelta& delay) const {
- DCHECK(thread_checker_.CalledOnValidThread());
- if (is_signaled()) {
- if (delay.is_zero())
- runner->PostTask(from_here, std::move(task));
- else
- runner->PostDelayedTask(from_here, std::move(task), delay);
- } else {
- tasks_.emplace_back(from_here, std::move(runner), std::move(task), delay);
- }
- }
- } // namespace base
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