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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.
#ifndef BASE_MESSAGE_LOOP_PENDING_TASK_QUEUE_H_
#define BASE_MESSAGE_LOOP_PENDING_TASK_QUEUE_H_
#include "base/macros.h"
#include "base/pending_task.h"
#include "base/sequence_checker.h"
namespace base {
namespace internal {
// Provides storage for tasks deferred by MessageLoop via DelayedQueue and
// DeferredQueue.
class PendingTaskQueue {
public:
// Provides a read-write task queue.
class Queue {
public:
Queue() = default;
virtual ~Queue() = default;
// Returns the next task. HasTasks() is assumed to be true.
virtual const PendingTask& Peek() = 0;
// Removes and returns the next task. HasTasks() is assumed to be true.
virtual PendingTask Pop() = 0;
// Whether this queue has tasks.
virtual bool HasTasks() = 0;
// Removes all tasks.
virtual void Clear() = 0;
// Adds the task to the end of the queue.
virtual void Push(PendingTask pending_task) = 0;
private:
DISALLOW_COPY_AND_ASSIGN(Queue);
};
PendingTaskQueue();
~PendingTaskQueue();
Queue& delayed_tasks() { return delayed_tasks_; }
Queue& deferred_tasks() { return deferred_tasks_; }
bool HasPendingHighResolutionTasks() const {
return delayed_tasks_.HasPendingHighResolutionTasks();
}
// Reports UMA metrics about its queues before the MessageLoop goes to sleep
// per being idle.
void ReportMetricsOnIdle() const;
private:
// The queue for holding tasks that should be run later and sorted by expected
// run time.
class DelayedQueue : public Queue {
public:
DelayedQueue();
~DelayedQueue() override;
// Queue:
const PendingTask& Peek() override;
PendingTask Pop() override;
// Whether this queue has tasks after sweeping the cancelled ones in front.
bool HasTasks() override;
void Clear() override;
void Push(PendingTask pending_task) override;
size_t Size() const;
bool HasPendingHighResolutionTasks() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return pending_high_res_tasks_ > 0;
}
private:
DelayedTaskQueue queue_;
// Number of high resolution tasks in |queue_|.
int pending_high_res_tasks_ = 0;
SEQUENCE_CHECKER(sequence_checker_);
DISALLOW_COPY_AND_ASSIGN(DelayedQueue);
};
// The queue for holding tasks that couldn't be run while the MessageLoop was
// nested. These are generally processed during the idle stage.
class DeferredQueue : public Queue {
public:
DeferredQueue();
~DeferredQueue() override;
// Queue:
const PendingTask& Peek() override;
PendingTask Pop() override;
bool HasTasks() override;
void Clear() override;
void Push(PendingTask pending_task) override;
private:
TaskQueue queue_;
SEQUENCE_CHECKER(sequence_checker_);
DISALLOW_COPY_AND_ASSIGN(DeferredQueue);
};
DelayedQueue delayed_tasks_;
DeferredQueue deferred_tasks_;
DISALLOW_COPY_AND_ASSIGN(PendingTaskQueue);
};
} // namespace internal
} // namespace base
#endif // BASE_MESSAGE_LOOP_PENDING_TASK_QUEUE_H_