gecko-dev/layout/base/nsRefreshDriver.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* 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/Vector.h"
#include "mozilla/WeakPtr.h"
#include "nsTObserverArray.h"
#include "nsTArray.h"
#include "nsTHashtable.h"
#include "nsTObserverArray.h"
#include "nsClassHashtable.h"
#include "nsHashKeys.h"
#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"
#include "GeckoProfiler.h"
#include "mozilla/layers/TransactionIdAllocator.h"
class nsPresContext;
class nsIPresShell;
class nsIDocument;
class imgIRequest;
class nsIDOMEvent;
class nsINode;
class nsIRunnable;
namespace mozilla {
class RefreshDriverTimer;
namespace layout {
class VsyncChild;
} // namespace layout
} // 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
virtual void WillRefresh(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
{
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;
/**
* Same thing, but in microseconds since the epoch.
*/
int64_t MostRecentRefreshEpochTime() const;
/**
* Add / remove refresh observers. Returns whether the operation
* succeeded.
*
* 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.
*/
bool AddRefreshObserver(nsARefreshObserver *aObserver,
mozilla::FlushType aFlushType);
bool RemoveRefreshObserver(nsARefreshObserver *aObserver,
mozilla::FlushType aFlushType);
/**
* 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 that we should flush style and layout on
*/
bool AddStyleFlushObserver(nsIPresShell* aShell) {
NS_ASSERTION(!mStyleFlushObservers.Contains(aShell),
"Double-adding style flush observer");
// We only get the cause for the first observer each frame because capturing
// a stack is expensive. This is still useful if (1) you're trying to remove
// all flushes for a particial frame or (2) the costly flush is triggered
// near the call site where the first observer is triggered.
if (!mStyleCause) {
mStyleCause = profiler_get_backtrace();
}
bool appended = mStyleFlushObservers.AppendElement(aShell) != nullptr;
EnsureTimerStarted();
return appended;
}
void RemoveStyleFlushObserver(nsIPresShell* aShell) {
mStyleFlushObservers.RemoveElement(aShell);
}
bool AddLayoutFlushObserver(nsIPresShell* aShell) {
NS_ASSERTION(!IsLayoutFlushObserver(aShell),
"Double-adding layout flush observer");
// We only get the cause for the first observer each frame because capturing
// a stack is expensive. This is still useful if (1) you're trying to remove
// all flushes for a particial frame or (2) the costly flush is triggered
// near the call site where the first observer is triggered.
if (!mReflowCause) {
mReflowCause = profiler_get_backtrace();
}
bool appended = mLayoutFlushObservers.AppendElement(aShell) != nullptr;
EnsureTimerStarted();
return appended;
}
void RemoveLayoutFlushObserver(nsIPresShell* aShell) {
mLayoutFlushObservers.RemoveElement(aShell);
}
bool IsLayoutFlushObserver(nsIPresShell* aShell) {
return mLayoutFlushObservers.Contains(aShell);
}
/**
* "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;
}
/**
* Add a document for which we have FrameRequestCallbacks
*/
void ScheduleFrameRequestCallbacks(nsIDocument* aDocument);
/**
* Remove a document for which we have FrameRequestCallbacks
*/
void RevokeFrameRequestCallbacks(nsIDocument* aDocument);
/**
* Queue a new event to dispatch in next tick before the style flush
*/
void ScheduleEventDispatch(nsINode* aTarget, nsIDOMEvent* aEvent);
/**
* Cancel all pending events scheduled by ScheduleEventDispatch which
* targets any node in aDocument.
*/
void CancelPendingEvents(nsIDocument* aDocument);
/**
* 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
uint64_t GetTransactionId() override;
uint64_t LastTransactionId() const override;
void NotifyTransactionCompleted(uint64_t aTransactionId) override;
void RevokeTransactionId(uint64_t aTransactionId) override;
void ClearPendingTransactions() override;
void ResetInitialTransactionId(uint64_t aTransactionId) override;
mozilla::TimeStamp GetTransactionStart() 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);
static void DispatchIdleRunnableAfterTick(nsIRunnable* aRunnable,
uint32_t aDelay);
static void CancelIdleRunnable(nsIRunnable* aRunnable);
bool SkippedPaints() const
{
return mSkippedPaints;
}
private:
typedef nsTObserverArray<nsARefreshObserver*> ObserverArray;
typedef nsTHashtable<nsISupportsHashKey> RequestTable;
struct ImageStartData {
ImageStartData()
{
}
mozilla::Maybe<mozilla::TimeStamp> mStartTime;
RequestTable mEntries;
};
typedef nsClassHashtable<nsUint32HashKey, ImageStartData> ImageStartTable;
void DispatchPendingEvents();
void DispatchAnimationEvents();
void RunFrameRequestCallbacks(mozilla::TimeStamp aNowTime);
void Tick(int64_t aNowEpoch, mozilla::TimeStamp aNowTime);
enum EnsureTimerStartedFlags {
eNone = 0,
eForceAdjustTimer = 1 << 0,
eAllowTimeToGoBackwards = 1 << 1,
eNeverAdjustTimer = 1 << 2,
};
void EnsureTimerStarted(EnsureTimerStartedFlags aFlags = eNone);
void StopTimer();
uint32_t ObserverCount() const;
uint32_t ImageRequestCount() const;
ObserverArray& ArrayFor(mozilla::FlushType aFlushType);
// Trigger a refresh immediately, if haven't been disconnected or frozen.
void DoRefresh();
double GetRefreshTimerInterval() const;
double GetRegularTimerInterval(bool *outIsDefault = nullptr) const;
static double GetThrottledTimerInterval();
static mozilla::TimeDuration GetMinRecomputeVisibilityInterval();
bool HaveFrameRequestCallbacks() const {
return mFrameRequestCallbackDocs.Length() != 0;
}
void FinishedWaitingForTransaction();
mozilla::RefreshDriverTimer* ChooseTimer() const;
mozilla::RefreshDriverTimer* mActiveTimer;
UniqueProfilerBacktrace mReflowCause;
UniqueProfilerBacktrace mStyleCause;
// nsPresContext passed in constructor and unset in Disconnect.
mozilla::WeakPtr<nsPresContext> mPresContext;
RefPtr<nsRefreshDriver> mRootRefresh;
// The most recently allocated transaction id.
uint64_t mPendingTransaction;
// The most recently completed transaction id.
uint64_t 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;
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;
int64_t mMostRecentRefreshEpochTime;
// 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 mMostRecentTick;
mozilla::TimeStamp mTickStart;
mozilla::TimeStamp mNextThrottledFrameRequestTick;
mozilla::TimeStamp mNextRecomputeVisibilityTick;
// separate arrays for each flush type we support
ObserverArray mObservers[3];
RequestTable mRequests;
ImageStartTable mStartTable;
AutoTArray<nsCOMPtr<nsIRunnable>, 16> mEarlyRunners;
struct PendingEvent {
nsCOMPtr<nsINode> mTarget;
nsCOMPtr<nsIDOMEvent> mEvent;
};
AutoTArray<nsIPresShell*, 16> mStyleFlushObservers;
AutoTArray<nsIPresShell*, 16> mLayoutFlushObservers;
// nsTArray on purpose, because we want to be able to swap.
nsTArray<nsIDocument*> mFrameRequestCallbackDocs;
nsTArray<nsIDocument*> mThrottledFrameRequestCallbackDocs;
nsTObserverArray<nsAPostRefreshObserver*> mPostRefreshObservers;
nsTArray<PendingEvent> mPendingEvents;
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_) */