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 "nsThreadUtils.h"
#include <functional>
namespace mozilla {
// 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 final : public CancelableIdleRunnable {
public:
// 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 will attempt to run in idle time, with a budget computed
// based on a (capped) estimate for how much idle time is available. If there
// is no idle time within `aMaxDelay` ms, it will fall back to running using
// a specified `aNonIdleBudget`.
static already_AddRefed<IdleTaskRunner> Create(
const CallbackType& aCallback, const char* aRunnableName,
uint32_t aMaxDelay, int64_t aNonIdleBudget, bool aRepeating,
const MayStopProcessingCallbackType& aMayStopProcessing);
NS_IMETHOD Run() override;
// (Used by the task triggering code.) Record the end of the current idle
// period, or null if not running during idle time.
void SetDeadline(mozilla::TimeStamp aDeadline) override;
void SetTimer(uint32_t aDelay, nsIEventTarget* aTarget) override;
// Update the non-idle time budgeted for this callback. This really only
// makes sense for a repeating runner.
void SetBudget(int64_t aBudget);
nsresult Cancel() override;
void Schedule(bool aAllowIdleDispatch);
private:
explicit IdleTaskRunner(
const CallbackType& aCallback, const char* aRunnableName,
uint32_t aMaxDelay, int64_t aNonIdleBudget, bool aRepeating,
const MayStopProcessingCallbackType& aMayStopProcessing);
~IdleTaskRunner();
void CancelTimer();
void SetTimerInternal(uint32_t aDelay);
nsCOMPtr<nsITimer> mTimer;
nsCOMPtr<nsITimer> mScheduleTimer;
CallbackType mCallback;
// Wait this long for idle time before giving up and running a non-idle
// callback.
uint32_t mDelay;
// 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 expected amount of time the callback will run for, when not running
// during idle time.
TimeDuration mBudget;
bool mRepeating;
bool mTimerActive;
MayStopProcessingCallbackType mMayStopProcessing;
const char* mName;
};
} // end of namespace mozilla.
#endif