layout/base/nsRefreshDriver.h
author Jan Varga <jan.varga@gmail.com>
Fri, 23 Aug 2019 04:46:14 +0000
changeset 489534 5df00af5913e90ba7c60411e1e6cb78c2f7c46e0
parent 469632 35aed2f899c30a440c551d51d791c0986db8ac7f
permissions -rw-r--r--
Bug 1563023 - Part 4: Get rid of custom usage tracking in LS by using client usage tracked by QM; r=asuth This patch gets rid of gUsages in LSNG. This provides better consistency and makes it easier to cache quota info on disk. The patch also fixes some edge cases when usage was not adjusted correctly after a failed file or database operation. Differential Revision: https://phabricator.services.mozilla.com/D38229

/* -*- 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/. */

/*
 * Code to notify things that animate before a refresh, at an appropriate
 * refresh rate.  (Perhaps temporary, until replaced by compositor.)
 */

#ifndef nsRefreshDriver_h_
#define nsRefreshDriver_h_

#include "mozilla/FlushType.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/Vector.h"
#include "mozilla/WeakPtr.h"
#include "nsTObserverArray.h"
#include "nsTArray.h"
#include "nsTHashtable.h"
#include "nsClassHashtable.h"
#include "nsHashKeys.h"
#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"
#include "mozilla/dom/VisualViewport.h"
#include "mozilla/layers/TransactionIdAllocator.h"
#include "mozilla/VsyncDispatcher.h"

class nsPresContext;

class imgIRequest;
class nsINode;
class nsIRunnable;

namespace mozilla {
class AnimationEventDispatcher;
class PendingFullscreenEvent;
class PresShell;
class RefreshDriverTimer;
class Runnable;

namespace layout {
class VsyncChild;
}  // namespace layout

namespace dom {
class Event;
}  // namespace dom

}  // namespace mozilla

/**
 * An abstract base class to be implemented by callers wanting to be
 * notified at refresh times.  When nothing needs to be painted, callers
 * may not be notified.
 */
class nsARefreshObserver {
 public:
  // AddRef and Release signatures that match nsISupports.  Implementors
  // must implement reference counting, and those that do implement
  // nsISupports will already have methods with the correct signature.
  //
  // The refresh driver does NOT hold references to refresh observers
  // except while it is notifying them.
  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING

  MOZ_CAN_RUN_SCRIPT virtual void WillRefresh(mozilla::TimeStamp aTime) = 0;
};

/**
 * An abstract base class to be implemented by callers wanting to be notified
 * when the observing refresh driver updated mMostRecentRefresh due to active
 * timer changes. Callers must ensure an observer is removed before it is
 * destroyed.
 */
class nsATimerAdjustmentObserver {
 public:
  virtual void NotifyTimerAdjusted(mozilla::TimeStamp aTime) = 0;
};

/**
 * An abstract base class to be implemented by callers wanting to be notified
 * that a refresh has occurred. Callers must ensure an observer is removed
 * before it is destroyed.
 */
class nsAPostRefreshObserver {
 public:
  virtual void DidRefresh() = 0;
};

class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
                              public nsARefreshObserver {
  using Document = mozilla::dom::Document;
  using TransactionId = mozilla::layers::TransactionId;
  using VVPResizeEvent =
      mozilla::dom::VisualViewport::VisualViewportResizeEvent;
  using VVPScrollEvent =
      mozilla::dom::VisualViewport::VisualViewportScrollEvent;

 public:
  explicit nsRefreshDriver(nsPresContext* aPresContext);
  ~nsRefreshDriver();

  /**
   * Methods for testing, exposed via nsIDOMWindowUtils.  See
   * nsIDOMWindowUtils.advanceTimeAndRefresh for description.
   */
  void AdvanceTimeAndRefresh(int64_t aMilliseconds);
  void RestoreNormalRefresh();
  void DoTick();
  bool IsTestControllingRefreshesEnabled() const {
    return mTestControllingRefreshes;
  }

  /**
   * Return the time of the most recent refresh.  This is intended to be
   * used by callers who want to start an animation now and want to know
   * what time to consider the start of the animation.  (This helps
   * ensure that multiple animations started during the same event off
   * the main event loop have the same start time.)
   */
  mozilla::TimeStamp MostRecentRefresh() const;

  /**
   * Add / remove refresh observers.
   * RemoveRefreshObserver returns true if aObserver was found.
   *
   * The flush type affects:
   *   + the order in which the observers are notified (lowest flush
   *     type to highest, in order registered)
   *   + (in the future) which observers are suppressed when the display
   *     doesn't require current position data or isn't currently
   *     painting, and, correspondingly, which get notified when there
   *     is a flush during such suppression
   * and it must be FlushType::Style, FlushType::Layout, or FlushType::Display.
   *
   * The refresh driver does NOT own a reference to these observers;
   * they must remove themselves before they are destroyed.
   *
   * The observer will be called even if there is no other activity.
   */
  void AddRefreshObserver(nsARefreshObserver* aObserver,
                          mozilla::FlushType aFlushType);
  bool RemoveRefreshObserver(nsARefreshObserver* aObserver,
                             mozilla::FlushType aFlushType);
  /**
   * Add / remove an observer wants to know the time when the refresh driver
   * updated the most recent refresh time due to its active timer changes.
   */
  void AddTimerAdjustmentObserver(nsATimerAdjustmentObserver* aObserver);
  void RemoveTimerAdjustmentObserver(nsATimerAdjustmentObserver* aObserver);

  void PostVisualViewportResizeEvent(VVPResizeEvent* aResizeEvent);
  void DispatchVisualViewportResizeEvents();

  void PostScrollEvent(mozilla::Runnable* aScrollEvent, bool aDelayed = false);
  void DispatchScrollEvents();

  void PostVisualViewportScrollEvent(VVPScrollEvent* aScrollEvent);
  void DispatchVisualViewportScrollEvents();

  /**
   * Add an observer that will be called after each refresh. The caller
   * must remove the observer before it is deleted. This does not trigger
   * refresh driver ticks.
   */
  void AddPostRefreshObserver(nsAPostRefreshObserver* aObserver);
  void RemovePostRefreshObserver(nsAPostRefreshObserver* aObserver);

  /**
   * Add/Remove imgIRequest versions of observers.
   *
   * These are used for hooking into the refresh driver for
   * controlling animated images.
   *
   * @note The refresh driver owns a reference to these listeners.
   *
   * @note Technically, imgIRequest objects are not nsARefreshObservers, but
   * for controlling animated image repaint events, we subscribe the
   * imgIRequests to the nsRefreshDriver for notification of paint events.
   *
   * @returns whether the operation succeeded, or void in the case of removal.
   */
  bool AddImageRequest(imgIRequest* aRequest);
  void RemoveImageRequest(imgIRequest* aRequest);

  /**
   * Add / remove presshells which have pending resize event.
   */
  void AddResizeEventFlushObserver(mozilla::PresShell* aPresShell,
                                   bool aDelayed = false) {
    MOZ_DIAGNOSTIC_ASSERT(
        !mResizeEventFlushObservers.Contains(aPresShell) &&
            !mDelayedResizeEventFlushObservers.Contains(aPresShell),
        "Double-adding resize event flush observer");
    if (aDelayed) {
      mDelayedResizeEventFlushObservers.AppendElement(aPresShell);
    } else {
      mResizeEventFlushObservers.AppendElement(aPresShell);
      EnsureTimerStarted();
    }
  }

  void RemoveResizeEventFlushObserver(mozilla::PresShell* aPresShell) {
    mResizeEventFlushObservers.RemoveElement(aPresShell);
    mDelayedResizeEventFlushObservers.RemoveElement(aPresShell);
  }

  /**
   * Add / remove presshells that we should flush style and layout on
   */
  void AddStyleFlushObserver(mozilla::PresShell* aPresShell) {
    MOZ_DIAGNOSTIC_ASSERT(!mStyleFlushObservers.Contains(aPresShell),
                          "Double-adding style flush observer");
    mStyleFlushObservers.AppendElement(aPresShell);
    EnsureTimerStarted();
  }

  void RemoveStyleFlushObserver(mozilla::PresShell* aPresShell) {
    mStyleFlushObservers.RemoveElement(aPresShell);
  }
  void AddLayoutFlushObserver(mozilla::PresShell* aPresShell) {
    MOZ_DIAGNOSTIC_ASSERT(!IsLayoutFlushObserver(aPresShell),
                          "Double-adding layout flush observer");
    mLayoutFlushObservers.AppendElement(aPresShell);
    EnsureTimerStarted();
  }
  void RemoveLayoutFlushObserver(mozilla::PresShell* aPresShell) {
    mLayoutFlushObservers.RemoveElement(aPresShell);
  }

  bool IsLayoutFlushObserver(mozilla::PresShell* aPresShell) {
    return mLayoutFlushObservers.Contains(aPresShell);
  }

  /**
   * "Early Runner" runnables will be called as the first step when refresh
   * driver tick is triggered. Runners shouldn't keep other objects alive,
   * since it isn't guaranteed they will ever get called.
   */
  void AddEarlyRunner(nsIRunnable* aRunnable) {
    mEarlyRunners.AppendElement(aRunnable);
    EnsureTimerStarted();
  }

  /**
   * Remember whether our presshell's view manager needs a flush
   */
  void ScheduleViewManagerFlush();
  void RevokeViewManagerFlush() { mViewManagerFlushIsPending = false; }
  bool ViewManagerFlushIsPending() { return mViewManagerFlushIsPending; }
  bool HasScheduleFlush() { return mHasScheduleFlush; }

  /**
   * Add a document for which we have FrameRequestCallbacks
   */
  void ScheduleFrameRequestCallbacks(Document* aDocument);

  /**
   * Remove a document for which we have FrameRequestCallbacks
   */
  void RevokeFrameRequestCallbacks(Document* aDocument);

  /**
   * Queue a new fullscreen event to be dispatched in next tick before
   * the style flush
   */
  void ScheduleFullscreenEvent(
      mozilla::UniquePtr<mozilla::PendingFullscreenEvent> aEvent);

  /**
   * Cancel all pending fullscreen events scheduled by ScheduleFullscreenEvent
   * which targets any node in aDocument.
   */
  void CancelPendingFullscreenEvents(Document* aDocument);

  /**
   * Queue new animation events to dispatch in next tick.
   */
  void ScheduleAnimationEventDispatch(
      mozilla::AnimationEventDispatcher* aDispatcher) {
    NS_ASSERTION(!mAnimationEventFlushObservers.Contains(aDispatcher),
                 "Double-adding animation event flush observer");
    mAnimationEventFlushObservers.AppendElement(aDispatcher);
    EnsureTimerStarted();
  }

  /**
   * Cancel all pending animation events associated with |aDispatcher|.
   */
  void CancelPendingAnimationEvents(
      mozilla::AnimationEventDispatcher* aDispatcher);

  /**
   * Schedule a frame visibility update "soon", subject to the heuristics and
   * throttling we apply to visibility updates.
   */
  void ScheduleFrameVisibilityUpdate() { mNeedToRecomputeVisibility = true; }

  /**
   * Tell the refresh driver that it is done driving refreshes and
   * should stop its timer and forget about its pres context.  This may
   * be called from within a refresh.
   */
  void Disconnect();

  bool IsFrozen() { return mFreezeCount > 0; }

  /**
   * Freeze the refresh driver.  It should stop delivering future
   * refreshes until thawed. Note that the number of calls to Freeze() must
   * match the number of calls to Thaw() in order for the refresh driver to
   * be un-frozen.
   */
  void Freeze();

  /**
   * Thaw the refresh driver.  If the number of calls to Freeze() matches the
   * number of calls to this function, the refresh driver should start
   * delivering refreshes again.
   */
  void Thaw();

  /**
   * Throttle or unthrottle the refresh driver.  This is done if the
   * corresponding presshell is hidden or shown.
   */
  void SetThrottled(bool aThrottled);

  /**
   * Return the prescontext we were initialized with
   */
  nsPresContext* GetPresContext() const { return mPresContext; }

  /**
   * PBackgroundChild actor is created asynchronously in content process.
   * We can't create vsync-based timers during PBackground startup. This
   * function will be called when PBackgroundChild actor is created. Then we can
   * do the pending vsync-based timer creation.
   */
  static void PVsyncActorCreated(mozilla::layout::VsyncChild* aVsyncChild);

#ifdef DEBUG
  /**
   * Check whether the given observer is an observer for the given flush type
   */
  bool IsRefreshObserver(nsARefreshObserver* aObserver,
                         mozilla::FlushType aFlushType);
#endif

  /**
   * Default interval the refresh driver uses, in ms.
   */
  static int32_t DefaultInterval();

  bool IsInRefresh() { return mInRefresh; }

  void SetIsResizeSuppressed() { mResizeSuppressed = true; }
  bool IsResizeSuppressed() const { return mResizeSuppressed; }

  /**
   * The latest value of process-wide jank levels.
   *
   * For each i, sJankLevels[i] counts the number of times delivery of
   * vsync to the main thread has been delayed by at least 2^i
   * ms. This data structure has been designed to make it easy to
   * determine how much jank has taken place between two instants in
   * time.
   *
   * Return `false` if `aJank` needs to be grown to accomodate the
   * data but we didn't have enough memory.
   */
  static bool GetJankLevels(mozilla::Vector<uint64_t>& aJank);

  // mozilla::layers::TransactionIdAllocator
  TransactionId GetTransactionId(bool aThrottle) override;
  TransactionId LastTransactionId() const override;
  void NotifyTransactionCompleted(TransactionId aTransactionId) override;
  void RevokeTransactionId(TransactionId aTransactionId) override;
  void ClearPendingTransactions() override;
  void ResetInitialTransactionId(TransactionId aTransactionId) override;
  mozilla::TimeStamp GetTransactionStart() override;
  mozilla::VsyncId GetVsyncId() override;
  mozilla::TimeStamp GetVsyncStart() override;

  bool IsWaitingForPaint(mozilla::TimeStamp aTime);

  // nsARefreshObserver
  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override {
    return TransactionIdAllocator::AddRef();
  }
  NS_IMETHOD_(MozExternalRefCountType) Release(void) override {
    return TransactionIdAllocator::Release();
  }
  virtual void WillRefresh(mozilla::TimeStamp aTime) override;

  /**
   * Compute the time when the currently active refresh driver timer
   * will start its next tick.
   *
   * Expects a non-null default value that is the upper bound of the
   * expected deadline. If the next expected deadline is later than
   * the default value, the default value is returned.
   *
   * If we're animating and we have skipped paints a time in the past
   * is returned.
   */
  static mozilla::TimeStamp GetIdleDeadlineHint(mozilla::TimeStamp aDefault);

  /**
   * It returns the expected timestamp of the next tick or nothing if the next
   * tick is missed.
   */
  static mozilla::Maybe<mozilla::TimeStamp> GetNextTickHint();

  static void DispatchIdleRunnableAfterTickUnlessExists(nsIRunnable* aRunnable,
                                                        uint32_t aDelay);
  static void CancelIdleRunnable(nsIRunnable* aRunnable);

  void NotifyDOMContentLoaded();

  // Schedule a refresh so that any delayed events will run soon.
  void RunDelayedEventsSoon();

  void InitializeTimer() {
    MOZ_ASSERT(!mActiveTimer);
    EnsureTimerStarted();
  }

 private:
  typedef nsTObserverArray<nsARefreshObserver*> ObserverArray;
  typedef nsTArray<RefPtr<VVPResizeEvent>> VisualViewportResizeEventArray;
  typedef nsTArray<RefPtr<mozilla::Runnable>> ScrollEventArray;
  typedef nsTArray<RefPtr<VVPScrollEvent>> VisualViewportScrollEventArray;
  typedef nsTHashtable<nsISupportsHashKey> RequestTable;
  struct ImageStartData {
    ImageStartData() {}

    mozilla::Maybe<mozilla::TimeStamp> mStartTime;
    RequestTable mEntries;
  };
  typedef nsClassHashtable<nsUint32HashKey, ImageStartData> ImageStartTable;

  void RunFullscreenSteps();
  void DispatchAnimationEvents();
  MOZ_CAN_RUN_SCRIPT
  void RunFrameRequestCallbacks(mozilla::TimeStamp aNowTime);
  void UpdateIntersectionObservations();
  MOZ_CAN_RUN_SCRIPT_BOUNDARY
  void Tick(mozilla::VsyncId aId, mozilla::TimeStamp aNowTime);

  enum EnsureTimerStartedFlags {
    eNone = 0,
    eForceAdjustTimer = 1 << 0,
    eAllowTimeToGoBackwards = 1 << 1,
    eNeverAdjustTimer = 1 << 2,
  };
  void EnsureTimerStarted(EnsureTimerStartedFlags aFlags = eNone);
  void StopTimer();

  bool HasObservers() const;
  // Note: This should only be called in the dtor of nsRefreshDriver.
  uint32_t ObserverCount() const;
  bool HasImageRequests() const;
  ObserverArray& ArrayFor(mozilla::FlushType aFlushType);
  // Trigger a refresh immediately, if haven't been disconnected or frozen.
  void DoRefresh();

  double GetRegularTimerInterval() const;
  static double GetThrottledTimerInterval();

  static mozilla::TimeDuration GetMinRecomputeVisibilityInterval();

  bool HaveFrameRequestCallbacks() const {
    return mFrameRequestCallbackDocs.Length() != 0;
  }

  void FinishedWaitingForTransaction();

  mozilla::RefreshDriverTimer* ChooseTimer() const;
  mozilla::RefreshDriverTimer* mActiveTimer;

  // nsPresContext passed in constructor and unset in Disconnect.
  mozilla::WeakPtr<nsPresContext> mPresContext;

  RefPtr<nsRefreshDriver> mRootRefresh;

  // The most recently allocated transaction id.
  TransactionId mNextTransactionId;
  // This number is mCompletedTransaction + (pending transaction count).
  // When we revoke a transaction id, we revert this number (since it's
  // no longer outstanding), but not mNextTransactionId (since we don't
  // want to reuse the number).
  TransactionId mOutstandingTransactionId;
  // The most recently completed transaction id.
  TransactionId mCompletedTransaction;

  uint32_t mFreezeCount;

  // How long we wait between ticks for throttled (which generally means
  // non-visible) documents registered with a non-throttled refresh driver.
  const mozilla::TimeDuration mThrottledFrameRequestInterval;

  // How long we wait, at a minimum, before recomputing approximate frame
  // visibility information. This is a minimum because, regardless of this
  // interval, we only recompute visibility when we've seen a layout or style
  // flush since the last time we did it.
  const mozilla::TimeDuration mMinRecomputeVisibilityInterval;

  bool mThrottled;
  bool mNeedToRecomputeVisibility;
  bool mTestControllingRefreshes;
  bool mViewManagerFlushIsPending;

  // True if the view manager needs a flush. Layers-free mode uses this value
  // to know when to notify invalidation.
  bool mHasScheduleFlush;

  bool mInRefresh;

  // True if the refresh driver is suspended waiting for transaction
  // id's to be returned and shouldn't do any work during Tick().
  bool mWaitingForTransaction;
  // True if Tick() was skipped because of mWaitingForTransaction and
  // we should schedule a new Tick immediately when resumed instead
  // of waiting until the next interval.
  bool mSkippedPaints;

  // True if view managers should delay any resize request until the
  // next tick by the refresh driver. This flag will be reset at the
  // start of every tick.
  bool mResizeSuppressed;

  // True if the next tick should notify DOMContentFlushed.
  bool mNotifyDOMContentFlushed;

  // Number of seconds that the refresh driver is blocked waiting for a
  // compositor transaction to be completed before we append a note to the gfx
  // critical log. The number is doubled every time the threshold is hit.
  uint64_t mWarningThreshold;
  mozilla::TimeStamp mMostRecentRefresh;
  mozilla::TimeStamp mTickStart;
  mozilla::VsyncId mTickVsyncId;
  mozilla::TimeStamp mTickVsyncTime;
  mozilla::TimeStamp mNextThrottledFrameRequestTick;
  mozilla::TimeStamp mNextRecomputeVisibilityTick;
  mozilla::TimeStamp mInitialTimerRunningLimit;

  // separate arrays for each flush type we support
  ObserverArray mObservers[4];
  // These observers should NOT be included in HasObservers() since that method
  // is used to determine whether or not to stop the timer, or restore it when
  // thawing the refresh driver. On the other hand these observers are intended
  // to be called when the timer is re-started and should not influence its
  // starting or stopping.
  nsTObserverArray<nsATimerAdjustmentObserver*> mTimerAdjustmentObservers;
  RequestTable mRequests;
  ImageStartTable mStartTable;
  AutoTArray<nsCOMPtr<nsIRunnable>, 16> mEarlyRunners;
  VisualViewportResizeEventArray mVisualViewportResizeEvents;
  ScrollEventArray mScrollEvents;
  VisualViewportScrollEventArray mVisualViewportScrollEvents;

  // Scroll events on documents that might have events suppressed.
  ScrollEventArray mDelayedScrollEvents;

  AutoTArray<mozilla::PresShell*, 16> mResizeEventFlushObservers;
  AutoTArray<mozilla::PresShell*, 16> mDelayedResizeEventFlushObservers;
  AutoTArray<mozilla::PresShell*, 16> mStyleFlushObservers;
  AutoTArray<mozilla::PresShell*, 16> mLayoutFlushObservers;
  // nsTArray on purpose, because we want to be able to swap.
  nsTArray<Document*> mFrameRequestCallbackDocs;
  nsTArray<Document*> mThrottledFrameRequestCallbackDocs;
  nsTObserverArray<nsAPostRefreshObserver*> mPostRefreshObservers;
  nsTArray<mozilla::UniquePtr<mozilla::PendingFullscreenEvent>>
      mPendingFullscreenEvents;
  AutoTArray<mozilla::AnimationEventDispatcher*, 16>
      mAnimationEventFlushObservers;

  void BeginRefreshingImages(RequestTable& aEntries,
                             mozilla::TimeStamp aDesired);

  friend class mozilla::RefreshDriverTimer;

  static void Shutdown();

  // `true` if we are currently in jank-critical mode.
  //
  // In jank-critical mode, any iteration of the event loop that takes
  // more than 16ms to compute will cause an ongoing animation to miss
  // frames.
  //
  // For simplicity, the current implementation assumes that we are
  // in jank-critical mode if and only if the vsync driver has at least
  // one observer.
  static bool IsJankCritical();
};

#endif /* !defined(nsRefreshDriver_h_) */