// 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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#ifndef V8_LIBPLATFORM_DEFAULT_FOREGROUND_TASK_RUNNER_H_
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#define V8_LIBPLATFORM_DEFAULT_FOREGROUND_TASK_RUNNER_H_
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#include <queue>
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#include "include/libplatform/libplatform.h"
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#include "include/v8-platform.h"
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#include "src/base/platform/condition-variable.h"
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#include "src/base/platform/mutex.h"
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namespace v8 {
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namespace platform {
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class V8_PLATFORM_EXPORT DefaultForegroundTaskRunner
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: public NON_EXPORTED_BASE(TaskRunner) {
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public:
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using TimeFunction = double (*)();
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DefaultForegroundTaskRunner(IdleTaskSupport idle_task_support,
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TimeFunction time_function);
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void Terminate();
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std::unique_ptr<Task> PopTaskFromQueue(MessageLoopBehavior wait_for_work);
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std::unique_ptr<IdleTask> PopTaskFromIdleQueue();
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void WaitForTaskLocked(const base::LockGuard<base::Mutex>&);
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double MonotonicallyIncreasingTime();
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// v8::TaskRunner implementation.
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void PostTask(std::unique_ptr<Task> task) override;
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void PostDelayedTask(std::unique_ptr<Task> task,
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double delay_in_seconds) override;
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void PostIdleTask(std::unique_ptr<IdleTask> task) override;
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bool IdleTasksEnabled() override;
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private:
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// The same as PostTask, but the lock is already held by the caller. The
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// {guard} parameter should make sure that the caller is holding the lock.
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void PostTaskLocked(std::unique_ptr<Task> task,
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const base::LockGuard<base::Mutex>&);
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// A caller of this function has to hold {lock_}. The {guard} parameter should
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// make sure that the caller is holding the lock.
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std::unique_ptr<Task> PopTaskFromDelayedQueueLocked(
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const base::LockGuard<base::Mutex>&);
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bool terminated_ = false;
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base::Mutex lock_;
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base::ConditionVariable event_loop_control_;
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std::queue<std::unique_ptr<Task>> task_queue_;
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IdleTaskSupport idle_task_support_;
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std::queue<std::unique_ptr<IdleTask>> idle_task_queue_;
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// Some helper constructs for the {delayed_task_queue_}.
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using DelayedEntry = std::pair<double, std::unique_ptr<Task>>;
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// Define a comparison operator for the delayed_task_queue_ to make sure
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// that the unique_ptr in the DelayedEntry is not accessed in the priority
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// queue. This is necessary because we have to reset the unique_ptr when we
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// remove a DelayedEntry from the priority queue.
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struct DelayedEntryCompare {
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bool operator()(DelayedEntry& left, DelayedEntry& right) {
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return left.first > right.first;
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}
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};
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std::priority_queue<DelayedEntry, std::vector<DelayedEntry>,
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DelayedEntryCompare>
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delayed_task_queue_;
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TimeFunction time_function_;
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};
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} // namespace platform
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} // namespace v8
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#endif // V8_LIBPLATFORM_DEFAULT_FOREGROUND_TASK_RUNNER_H_
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