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// Copyright 2015 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.
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_SCHEDULER_COMMON_SCHEDULER_HELPER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_SCHEDULER_COMMON_SCHEDULER_HELPER_H_
#include <stddef.h>
#include <memory>
#include "base/macros.h"
#include "base/message_loop/message_loop.h"
#include "base/task/sequence_manager/sequence_manager.h"
#include "base/time/tick_clock.h"
#include "third_party/blink/public/platform/task_type.h"
#include "third_party/blink/renderer/platform/platform_export.h"
namespace blink {
namespace scheduler {
// Common scheduler functionality for default tasks.
class PLATFORM_EXPORT SchedulerHelper
: public base::sequence_manager::SequenceManager::Observer {
public:
explicit SchedulerHelper(
std::unique_ptr<base::sequence_manager::SequenceManager>
sequence_manager);
~SchedulerHelper() override;
// SequenceManager::Observer implementation:
void OnBeginNestedRunLoop() override;
void OnExitNestedRunLoop() override;
const base::TickClock* GetClock() const;
base::TimeTicks NowTicks() const;
void SetTimerSlack(base::TimerSlack timer_slack);
// Returns the default task queue.
virtual scoped_refptr<base::sequence_manager::TaskQueue>
DefaultTaskQueue() = 0;
// Returns the control task queue. Tasks posted to this queue are executed
// with the highest priority. Care must be taken to avoid starvation of other
// task queues.
virtual scoped_refptr<base::sequence_manager::TaskQueue>
ControlTaskQueue() = 0;
// Returns task runner for the default queue.
scoped_refptr<base::SingleThreadTaskRunner> DefaultTaskRunner();
// Adds or removes a task observer from the scheduler. The observer will be
// notified before and after every executed task. These functions can only be
// called on the thread this class was created on.
void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer);
void RemoveTaskObserver(base::MessageLoop::TaskObserver* task_observer);
void AddTaskTimeObserver(
base::sequence_manager::TaskTimeObserver* task_time_observer);
void RemoveTaskTimeObserver(
base::sequence_manager::TaskTimeObserver* task_time_observer);
// Shuts down the scheduler by dropping any remaining pending work in the work
// queues. After this call any work posted to the task queue will be
// silently dropped.
void Shutdown();
// Returns true if Shutdown() has been called. Otherwise returns false.
bool IsShutdown() const { return !sequence_manager_.get(); }
inline void CheckOnValidThread() const {
DCHECK(thread_checker_.CalledOnValidThread());
}
class PLATFORM_EXPORT Observer {
public:
virtual ~Observer() = default;
// Called when scheduler executes task with nested run loop.
virtual void OnBeginNestedRunLoop() = 0;
// Called when the scheduler spots we've exited a nested run loop.
virtual void OnExitNestedRunLoop() = 0;
};
// Called once to set the Observer. This function is called on the main
// thread. If |observer| is null, then no callbacks will occur.
// Note |observer| is expected to outlive the SchedulerHelper.
void SetObserver(Observer* observer);
// Remove all canceled delayed tasks.
void SweepCanceledDelayedTasks();
// Accessor methods.
base::sequence_manager::TimeDomain* real_time_domain() const;
void RegisterTimeDomain(base::sequence_manager::TimeDomain* time_domain);
void UnregisterTimeDomain(base::sequence_manager::TimeDomain* time_domain);
bool GetAndClearSystemIsQuiescentBit();
double GetSamplingRateForRecordingCPUTime() const;
bool HasCPUTimingForEachTask() const;
// Test helpers.
void SetWorkBatchSizeForTesting(size_t work_batch_size);
protected:
void InitDefaultQueues(
scoped_refptr<base::sequence_manager::TaskQueue> default_task_queue,
scoped_refptr<base::sequence_manager::TaskQueue> control_task_queue,
TaskType default_task_type);
base::ThreadChecker thread_checker_;
std::unique_ptr<base::sequence_manager::SequenceManager> sequence_manager_;
private:
friend class SchedulerHelperTest;
scoped_refptr<base::SingleThreadTaskRunner> default_task_runner_;
Observer* observer_; // NOT OWNED
DISALLOW_COPY_AND_ASSIGN(SchedulerHelper);
};
} // namespace scheduler
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_SCHEDULER_COMMON_SCHEDULER_HELPER_H_
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