gecko-dev/dom/base/TimeoutManager.h

/* -*- 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 mozilla_dom_TimeoutManager_h__
#define mozilla_dom_TimeoutManager_h__

#include "mozilla/dom/Timeout.h"

class nsITimeoutHandler;
class nsGlobalWindow;

namespace mozilla {
namespace dom {

// This class manages the timeouts in a Window's setTimeout/setInterval pool.
class TimeoutManager final
{
public:
  explicit TimeoutManager(nsGlobalWindow& aWindow);
  TimeoutManager(const TimeoutManager& rhs) = delete;
  void operator=(const TimeoutManager& rhs) = delete;

  bool IsRunningTimeout() const { return mTimeoutFiringDepth > 0; }

  static uint32_t GetNestingLevel() { return sNestingLevel; }
  static void SetNestingLevel(uint32_t aLevel) { sNestingLevel = aLevel; }

  bool HasTimeouts() const { return !mTimeouts.isEmpty(); }

  nsresult SetTimeout(nsITimeoutHandler* aHandler,
                      int32_t interval, bool aIsInterval,
                      mozilla::dom::Timeout::Reason aReason,
                      int32_t* aReturn);
  void ClearTimeout(int32_t aTimerId,
                    mozilla::dom::Timeout::Reason aReason);

  // The timeout implementation functions.
  void RunTimeout(mozilla::dom::Timeout* aTimeout);
  // Return true if |aTimeout| needs to be reinserted into the timeout list.
  bool RescheduleTimeout(mozilla::dom::Timeout* aTimeout, const TimeStamp& now,
                         bool aRunningPendingTimeouts);

  void ClearAllTimeouts();
  // Insert aTimeout into the list, before all timeouts that would
  // fire after it, but no earlier than mTimeoutInsertionPoint, if any.
  void InsertTimeoutIntoList(mozilla::dom::Timeout* aTimeout);
  uint32_t GetTimeoutId(mozilla::dom::Timeout::Reason aReason);

  // Apply back pressure to the window if the TabGroup ThrottledEventQueue
  // exists and has too many runnables waiting to run.  For example, increase
  // the minimum timer delay, etc.
  void MaybeApplyBackPressure();

  // Check the current ThrottledEventQueue depth and update the back pressure
  // state.  If the queue has drained back pressure may be canceled.
  void CancelOrUpdateBackPressure(nsGlobalWindow* aWindow);

  // When timers are being throttled and we reduce the thottle delay we must
  // reschedule.  The amount of the old throttle delay must be provided in
  // order to bound how many timers must be examined.
  nsresult ResetTimersForThrottleReduction();

  int32_t DOMMinTimeoutValue() const;

  // aTimeout is the timeout that we're about to start running.  This function
  // returns the current timeout.
  mozilla::dom::Timeout* BeginRunningTimeout(mozilla::dom::Timeout* aTimeout);
  // aTimeout is the last running timeout.
  void EndRunningTimeout(mozilla::dom::Timeout* aTimeout);

  void UnmarkGrayTimers();

  // These four methods are intended to be called from the corresponding methods
  // on nsGlobalWindow.
  void Suspend();
  void Resume();
  void Freeze();
  void Thaw();

  // Initialize TimeoutManager before the first time it is accessed.
  static void Initialize();

  // Run some code for each Timeout in our list.
  template <class Callable>
  void ForEachTimeout(Callable c)
  {
    for (Timeout* timeout = mTimeouts.getFirst();
         timeout;
         timeout = timeout->getNext()) {
      c(timeout);
    }
  }

private:
  nsresult ResetTimersForThrottleReduction(int32_t aPreviousThrottleDelayMS);

private:
  // Each nsGlobalWindow object has a TimeoutManager member.  This reference
  // points to that holder object.
  nsGlobalWindow&             mWindow;
  // mTimeouts is generally sorted by mWhen, unless mTimeoutInsertionPoint is
  // non-null.  In that case, the dummy timeout pointed to by
  // mTimeoutInsertionPoint may have a later mWhen than some of the timeouts
  // that come after it.
  mozilla::LinkedList<mozilla::dom::Timeout> mTimeouts;
  // If mTimeoutInsertionPoint is non-null, insertions should happen after it.
  // This is a dummy timeout at the moment; if that ever changes, the logic in
  // ResetTimersForThrottleReduction needs to change.
  mozilla::dom::Timeout*      mTimeoutInsertionPoint;
  uint32_t                    mTimeoutIdCounter;
  uint32_t                    mTimeoutFiringDepth;
  mozilla::dom::Timeout*      mRunningTimeout;

   // The current idle request callback timeout handle
  uint32_t                    mIdleCallbackTimeoutCounter;

  int32_t                     mBackPressureDelayMS;

  static uint32_t             sNestingLevel;
};

}
}

#endif