chromium/third_party/blink/renderer/platform/scheduler/common/idle_helper.h

// Copyright 2015 The Chromium Authors
// 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_IDLE_HELPER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_SCHEDULER_COMMON_IDLE_HELPER_H_

#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/task/task_observer.h"
#include "base/time/time.h"
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/scheduler/common/cancelable_closure_holder.h"
#include "third_party/blink/renderer/platform/scheduler/common/scheduler_helper.h"
#include "third_party/blink/renderer/platform/scheduler/common/single_thread_idle_task_runner.h"

namespace blink {
namespace scheduler {
namespace idle_helper_unittest {
class BaseIdleHelperTest;
class IdleHelperTest;
}  // namespace idle_helper_unittest

class SchedulerHelper;

// The job of the IdleHelper is to run idle tasks when the system is otherwise
// idle. Idle tasks should be optional work, with no guarantee they will be run
// at all. Idle tasks are subject to three levels of throttling:
//
//   1. Both idle queues are run a BEST_EFFORT priority (i.e. only selected if
//      there is nothing else to do.
//   2. The idle queues are only enabled during an idle period.
//   3. Idle tasks posted from within an idle task run in the next idle period.
//      This is achieved by inserting a fence into the queue.
//
// There are two types of idle periods:
//   1. Short idle period - typically less than 10ms run after begin main frame
//      has finished, with the idle period ending at the compositor provided
//      deadline.
//   2. Long idle periods - typically up to 50ms when no frames are being
//      produced.
//
// Idle tasks are supplied a deadline, and should endeavor to finished before it
// ends to avoid jank.
class PLATFORM_EXPORT IdleHelper : public base::TaskObserver,
                                   public SingleThreadIdleTaskRunner::Delegate { … };

}  // namespace scheduler
}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_SCHEDULER_COMMON_IDLE_HELPER_H_