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