// Copyright 2017 the V8 project 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 "src/libplatform/default-foreground-task-runner.h"
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#include "src/base/platform/mutex.h"
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#include "src/libplatform/default-platform.h"
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namespace v8 {
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namespace platform {
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DefaultForegroundTaskRunner::DefaultForegroundTaskRunner(
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IdleTaskSupport idle_task_support, TimeFunction time_function)
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: idle_task_support_(idle_task_support), time_function_(time_function) {}
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void DefaultForegroundTaskRunner::Terminate() {
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base::LockGuard<base::Mutex> guard(&lock_);
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terminated_ = true;
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// Drain the task queues.
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while (!task_queue_.empty()) task_queue_.pop();
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while (!delayed_task_queue_.empty()) delayed_task_queue_.pop();
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while (!idle_task_queue_.empty()) idle_task_queue_.pop();
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}
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void DefaultForegroundTaskRunner::PostTaskLocked(
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std::unique_ptr<Task> task, const base::LockGuard<base::Mutex>&) {
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if (terminated_) return;
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task_queue_.push(std::move(task));
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event_loop_control_.NotifyOne();
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}
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void DefaultForegroundTaskRunner::PostTask(std::unique_ptr<Task> task) {
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base::LockGuard<base::Mutex> guard(&lock_);
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PostTaskLocked(std::move(task), guard);
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}
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double DefaultForegroundTaskRunner::MonotonicallyIncreasingTime() {
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return time_function_();
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}
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void DefaultForegroundTaskRunner::PostDelayedTask(std::unique_ptr<Task> task,
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double delay_in_seconds) {
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DCHECK_GE(delay_in_seconds, 0.0);
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base::LockGuard<base::Mutex> guard(&lock_);
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if (terminated_) return;
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double deadline = MonotonicallyIncreasingTime() + delay_in_seconds;
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delayed_task_queue_.push(std::make_pair(deadline, std::move(task)));
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}
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void DefaultForegroundTaskRunner::PostIdleTask(std::unique_ptr<IdleTask> task) {
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CHECK_EQ(IdleTaskSupport::kEnabled, idle_task_support_);
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base::LockGuard<base::Mutex> guard(&lock_);
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if (terminated_) return;
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idle_task_queue_.push(std::move(task));
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}
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bool DefaultForegroundTaskRunner::IdleTasksEnabled() {
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return idle_task_support_ == IdleTaskSupport::kEnabled;
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}
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std::unique_ptr<Task> DefaultForegroundTaskRunner::PopTaskFromQueue(
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MessageLoopBehavior wait_for_work) {
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base::LockGuard<base::Mutex> guard(&lock_);
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// Move delayed tasks that hit their deadline to the main queue.
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std::unique_ptr<Task> task = PopTaskFromDelayedQueueLocked(guard);
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while (task) {
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PostTaskLocked(std::move(task), guard);
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task = PopTaskFromDelayedQueueLocked(guard);
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}
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while (task_queue_.empty()) {
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if (wait_for_work == MessageLoopBehavior::kDoNotWait) return {};
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WaitForTaskLocked(guard);
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}
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task = std::move(task_queue_.front());
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task_queue_.pop();
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return task;
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}
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std::unique_ptr<Task>
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DefaultForegroundTaskRunner::PopTaskFromDelayedQueueLocked(
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const base::LockGuard<base::Mutex>&) {
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if (delayed_task_queue_.empty()) return {};
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double now = MonotonicallyIncreasingTime();
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const DelayedEntry& deadline_and_task = delayed_task_queue_.top();
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if (deadline_and_task.first > now) return {};
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// The const_cast here is necessary because there does not exist a clean way
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// to get a unique_ptr out of the priority queue. We provide the priority
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// queue with a custom comparison operator to make sure that the priority
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// queue does not access the unique_ptr. Therefore it should be safe to reset
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// the unique_ptr in the priority queue here. Note that the DelayedEntry is
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// removed from the priority_queue immediately afterwards.
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std::unique_ptr<Task> result =
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std::move(const_cast<DelayedEntry&>(deadline_and_task).second);
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delayed_task_queue_.pop();
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return result;
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}
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std::unique_ptr<IdleTask> DefaultForegroundTaskRunner::PopTaskFromIdleQueue() {
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base::LockGuard<base::Mutex> guard(&lock_);
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if (idle_task_queue_.empty()) return {};
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std::unique_ptr<IdleTask> task = std::move(idle_task_queue_.front());
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idle_task_queue_.pop();
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return task;
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}
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void DefaultForegroundTaskRunner::WaitForTaskLocked(
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const base::LockGuard<base::Mutex>&) {
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event_loop_control_.Wait(&lock_);
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}
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} // namespace platform
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} // namespace v8
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