gecko-dev/xpcom/threads/IdleTaskRunner.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef IdleTaskRunner_h
#define IdleTaskRunner_h
#include "mozilla/TimeStamp.h"
#include "mozilla/TaskCategory.h"
#include "mozilla/TaskController.h"
#include "nsThreadUtils.h"
#include <functional>
namespace mozilla {
class IdleTaskRunnerTask;
// A general purpose repeating callback runner (it can be configured to a
// one-time runner, too.) If it is running repeatedly, one has to either
// explicitly Cancel() the runner or have MayStopProcessing() callback return
// true to completely remove the runner.
class IdleTaskRunner {
public:
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(IdleTaskRunner)
// Return true if some meaningful work was done.
using CallbackType = std::function<bool(TimeStamp aDeadline)>;
// A callback for "stop processing" decision. Return true to
// stop processing. This can be an alternative to Cancel() or
// work together in different way.
using MayStopProcessingCallbackType = std::function<bool()>;
public:
// An IdleTaskRunner has (up to) three phases:
//
// - (duration aStartDelay) waiting to run (aStartDelay can be zero)
//
// - (duration aMaxDelay) attempting to find a long enough amount of idle
// time, at least aMinimumUsefulBudget
//
// - overdue for idle time, run as soon as possible
//
// If aRepeating is true, then aStartDelay applies only to the first run; the
// second run will attempt to run in the first idle slice that is long
// enough.
//
// All durations are in milliseconds.
//
static already_AddRefed<IdleTaskRunner> Create(
const CallbackType& aCallback, const char* aRunnableName,
TimeDuration aStartDelay, TimeDuration aMaxDelay,
TimeDuration aMinimumUsefulBudget, bool aRepeating,
const MayStopProcessingCallbackType& aMayStopProcessing);
void Run();
// (Used by the task triggering code.) Record the end of the current idle
// period, or null if not running during idle time.
void SetIdleDeadline(mozilla::TimeStamp aDeadline);
void SetTimer(TimeDuration aDelay, nsIEventTarget* aTarget);
// Update the minimum idle time that this callback would be invoked for.
void SetMinimumUsefulBudget(int64_t aMinimumUsefulBudget);
void Cancel();
void Schedule(bool aAllowIdleDispatch);
const char* GetName() { return mName; }
private:
explicit IdleTaskRunner(
const CallbackType& aCallback, const char* aRunnableName,
TimeDuration aStartDelay, TimeDuration aMaxDelay,
TimeDuration aMinimumUsefulBudget, bool aRepeating,
const MayStopProcessingCallbackType& aMayStopProcessing);
~IdleTaskRunner();
void CancelTimer();
void SetTimerInternal(TimeDuration aDelay);
nsCOMPtr<nsITimer> mTimer;
nsCOMPtr<nsITimer> mScheduleTimer;
CallbackType mCallback;
// Do not run until this time.
const mozilla::TimeStamp mStartTime;
// Wait this long for idle time before giving up and running a non-idle
// callback.
TimeDuration mMaxDelay;
// If running during idle time, the expected end of the current idle period.
// The null timestamp when the run is triggered by aMaxDelay instead of idle.
TimeStamp mDeadline;
// The least duration worth calling the callback for during idle time.
TimeDuration mMinimumUsefulBudget;
bool mRepeating;
bool mTimerActive;
MayStopProcessingCallbackType mMayStopProcessing;
const char* mName;
RefPtr<IdleTaskRunnerTask> mTask;
};
} // end of namespace mozilla.
#endif