Recover from buffer stuffing for canned animations (a3f13550) · Commits · e / os / android_frameworks_base

core/java/android/view/Choreographer.java

+154 −3

Original line number	Diff line number	Diff line
		@@ -189,6 +189,11 @@ public final class Choreographer {
		@UnsupportedAppUsage
		private long mLastFrameTimeNanos;

		// Keeps track of the last scheduled frame time without additional offsets
		// added from buffer stuffing recovery. Used to compare timing of vsyncs to
		// determine idle state.
		private long mLastNoOffsetFrameTimeNanos;

		/** DO NOT USE since this will not updated when screen refresh changes. */
		@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R,
		publicAlternatives = "Use {@link android.view.Display#getRefreshRate} instead")
		@@ -203,6 +208,50 @@ public final class Choreographer {
		private final FrameData mFrameData = new FrameData();
		private volatile boolean mInDoFrameCallback = false;

		private static class BufferStuffingData {
		enum RecoveryAction {
		// No recovery
		NONE,
		// Recovery has started, adds a negative offset
		OFFSET,
		// Recovery has started, delays a frame to return buffer count
		// back toward threshold.
		DELAY_FRAME
		}
		// The maximum number of times frames will be delayed per buffer stuffing event.
		// Since buffer stuffing can persist for several consecutive frames following the
		// initial missed frame, we want to adjust the timeline with enough frame delays and
		// offsets to return the queued buffer count back to threshold.
		public static final int MAX_FRAME_DELAYS = 3;

		// Whether buffer stuffing recovery has begun. Recovery can only end
		// when events are idle.
		public boolean isRecovering = false;

		// The number of frames delayed so far during recovery. Used to compare with
		// MAX_FRAME_DELAYS to safeguard against excessive frame delays during recovery.
		// Also used as unique cookie for tracing.
		public int numberFrameDelays = 0;

		// The number of additional frame delays scheduled during recovery to wait for the next
		// vsync. These are scheduled when frame times appear to go backward or frames are
		// being skipped due to FPSDivisor.
		public int numberWaitsForNextVsync = 0;

		/**
		* After buffer stuffing recovery has ended with a detected idle state, the
		* recovery data trackers can be reset in preparation for any future
		* stuffing events.
		*/
		public void reset() {
		isRecovering = false;
		numberFrameDelays = 0;
		numberWaitsForNextVsync = 0;
		}
		}

		private final BufferStuffingData mBufferStuffingData = new BufferStuffingData();

		/**
		* Contains information about the current frame for jank-tracking,
		* mainly timings of key events along with a bit of metadata about
		@@ -850,13 +899,99 @@ public final class Choreographer {
		Trace.traceEnd(Trace.TRACE_TAG_VIEW);
		}

		// Conducts logic for beginning or ending buffer stuffing recovery.
		// Returns an enum for the recovery action that should be taken in doFrame().
		BufferStuffingData.RecoveryAction checkBufferStuffingRecovery(long frameTimeNanos,
		DisplayEventReceiver.VsyncEventData vsyncEventData) {
		// Canned animations can recover from buffer stuffing whenever more
		// than 2 buffers are queued.
		if (vsyncEventData.numberQueuedBuffers > 2) {
		mBufferStuffingData.isRecovering = true;
		// Intentional frame delay that can happen at most MAX_FRAME_DELAYS times per
		// buffer stuffing event until the buffer count returns to threshold. The
		// delayed frames are compensated for by the negative offsets added to the
		// animation timestamps.
		if (mBufferStuffingData.numberFrameDelays < mBufferStuffingData.MAX_FRAME_DELAYS) {
		if (Trace.isTagEnabled(Trace.TRACE_TAG_VIEW)) {
		Trace.asyncTraceForTrackBegin(
		Trace.TRACE_TAG_VIEW, "Buffer stuffing recovery", "Thread "
		+ android.os.Process.myTid() + ", recover frame #"
		+ mBufferStuffingData.numberFrameDelays,
		mBufferStuffingData.numberFrameDelays);
		}
		mBufferStuffingData.numberFrameDelays++;
		scheduleVsyncLocked();
		return BufferStuffingData.RecoveryAction.DELAY_FRAME;
		}
		}

		if (mBufferStuffingData.isRecovering) {
		// Includes an additional expected frame delay from the natural scheduling
		// of the next vsync event.
		int totalFrameDelays = mBufferStuffingData.numberFrameDelays
		+ mBufferStuffingData.numberWaitsForNextVsync + 1;
		long vsyncsSinceLastCallback =
		(frameTimeNanos - mLastNoOffsetFrameTimeNanos) / mLastFrameIntervalNanos;

		// Detected idle state due to a longer inactive period since the last vsync callback
		// than the total expected number of vsync frame delays. End buffer stuffing recovery.
		// There are no frames to animate and offsets no longer need to be added
		// since the idle state gives the animation a chance to catch up.
		if (vsyncsSinceLastCallback > totalFrameDelays) {
		if (DEBUG_JANK) {
		Log.d(TAG, "End buffer stuffing recovery");
		}
		if (Trace.isTagEnabled(Trace.TRACE_TAG_VIEW)) {
		for (int i = 0; i < mBufferStuffingData.numberFrameDelays; i++) {
		Trace.asyncTraceForTrackEnd(
		Trace.TRACE_TAG_VIEW, "Buffer stuffing recovery", i);
		}
		}
		mBufferStuffingData.reset();

		} else {
		if (DEBUG_JANK) {
		Log.d(TAG, "Adjust animation timeline with a negative offset");
		}
		if (Trace.isTagEnabled(Trace.TRACE_TAG_VIEW)) {
		Trace.instantForTrack(
		Trace.TRACE_TAG_VIEW, "Buffer stuffing recovery",
		"Negative offset added to animation");
		}
		return BufferStuffingData.RecoveryAction.OFFSET;
		}
		}
		return BufferStuffingData.RecoveryAction.NONE;
		}

		void doFrame(long frameTimeNanos, int frame,
		DisplayEventReceiver.VsyncEventData vsyncEventData) {
		final long startNanos;
		final long frameIntervalNanos = vsyncEventData.frameInterval;
		boolean resynced = false;
		long offsetFrameTimeNanos = frameTimeNanos;

		// Evaluate if buffer stuffing recovery needs to start or end, and
		// what actions need to be taken for recovery.
		switch (checkBufferStuffingRecovery(frameTimeNanos, vsyncEventData)) {
		case NONE:
		// Without buffer stuffing recovery, offsetFrameTimeNanos is
		// synonymous with frameTimeNanos.
		break;
		case OFFSET:
		// Add animation offset. Used to update frame timeline with
		// offset before jitter is calculated.
		offsetFrameTimeNanos = frameTimeNanos - frameIntervalNanos;
		break;
		case DELAY_FRAME:
		// Intentional frame delay to help restore queued buffer count to threshold.
		return;
		default:
		break;
		}

		try {
		FrameTimeline timeline = mFrameData.update(frameTimeNanos, vsyncEventData);
		FrameTimeline timeline = mFrameData.update(offsetFrameTimeNanos, vsyncEventData);
		if (Trace.isTagEnabled(Trace.TRACE_TAG_VIEW)) {
		Trace.traceBegin(
		Trace.TRACE_TAG_VIEW, "Choreographer#doFrame " + timeline.mVsyncId);
		@@ -867,15 +1002,18 @@ public final class Choreographer {
		traceMessage("Frame not scheduled");
		return; // no work to do
		}
		mLastNoOffsetFrameTimeNanos = frameTimeNanos;

		if (DEBUG_JANK && mDebugPrintNextFrameTimeDelta) {
		mDebugPrintNextFrameTimeDelta = false;
		Log.d(TAG, "Frame time delta: "
		+ ((frameTimeNanos - mLastFrameTimeNanos) * 0.000001f) + " ms");
		+ ((offsetFrameTimeNanos - mLastFrameTimeNanos) * 0.000001f) + " ms");
		}

		long intendedFrameTimeNanos = frameTimeNanos;
		long intendedFrameTimeNanos = offsetFrameTimeNanos;
		startNanos = System.nanoTime();
		// Calculating jitter involves using the original frame time without
		// adjustments from buffer stuffing
		final long jitterNanos = startNanos - frameTimeNanos;
		if (jitterNanos >= frameIntervalNanos) {
		frameTimeNanos = startNanos;
		@@ -899,6 +1037,13 @@ public final class Choreographer {
		+ " ms in the past.");
		}
		}
		if (mBufferStuffingData.isRecovering) {
		frameTimeNanos -= frameIntervalNanos;
		if (DEBUG_JANK) {
		Log.d(TAG, "Adjusted animation timeline with a negative offset after"
		+ " jitter calculation");
		}
		}
		timeline = mFrameData.update(
		frameTimeNanos, mDisplayEventReceiver, jitterNanos);
		resynced = true;
		@@ -910,6 +1055,9 @@ public final class Choreographer {
		+ "previously skipped frame. Waiting for next vsync.");
		}
		traceMessage("Frame time goes backward");
		if (mBufferStuffingData.isRecovering) {
		mBufferStuffingData.numberWaitsForNextVsync++;
		}
		scheduleVsyncLocked();
		return;
		}
		@@ -918,6 +1066,9 @@ public final class Choreographer {
		long timeSinceVsync = frameTimeNanos - mLastFrameTimeNanos;
		if (timeSinceVsync < (frameIntervalNanos * mFPSDivisor) && timeSinceVsync > 0) {
		traceMessage("Frame skipped due to FPSDivisor");
		if (mBufferStuffingData.isRecovering) {
		mBufferStuffingData.numberWaitsForNextVsync++;
		}
		scheduleVsyncLocked();
		return;
		}

core/java/android/view/DisplayEventReceiver.java

+6 −1

Original line number	Diff line number	Diff line
		@@ -207,6 +207,8 @@ public abstract class DisplayEventReceiver {
		// reasonable timestamps.
		public int frameTimelinesLength = 1;

		public int numberQueuedBuffers = 0;

		VsyncEventData() {
		frameTimelines = new FrameTimeline[FRAME_TIMELINES_CAPACITY];
		for (int i = 0; i < frameTimelines.length; i++) {
		@@ -217,11 +219,13 @@ public abstract class DisplayEventReceiver {
		// Called from native code.
		@SuppressWarnings("unused")
		VsyncEventData(FrameTimeline[] frameTimelines, int preferredFrameTimelineIndex,
		int frameTimelinesLength, long frameInterval) {
		int frameTimelinesLength, long frameInterval,
		int numberQueuedBuffers) {
		this.frameTimelines = frameTimelines;
		this.preferredFrameTimelineIndex = preferredFrameTimelineIndex;
		this.frameTimelinesLength = frameTimelinesLength;
		this.frameInterval = frameInterval;
		this.numberQueuedBuffers = numberQueuedBuffers;
		}

		void copyFrom(VsyncEventData other) {
		@@ -231,6 +235,7 @@ public abstract class DisplayEventReceiver {
		for (int i = 0; i < frameTimelines.length; i++) {
		frameTimelines[i].copyFrom(other.frameTimelines[i]);
		}
		numberQueuedBuffers = other.numberQueuedBuffers;
		}

		public FrameTimeline preferredFrameTimeline() {

core/java/android/view/SurfaceControl.java

+25 −0

Original line number	Diff line number	Diff line
		@@ -22,6 +22,7 @@ import static android.graphics.Matrix.MSKEW_X;
		import static android.graphics.Matrix.MSKEW_Y;
		import static android.graphics.Matrix.MTRANS_X;
		import static android.graphics.Matrix.MTRANS_Y;
		import static android.view.flags.Flags.bufferStuffingRecovery;
		import static android.view.SurfaceControlProto.HASH_CODE;
		import static android.view.SurfaceControlProto.LAYER_ID;
		import static android.view.SurfaceControlProto.NAME;
		@@ -660,6 +661,13 @@ public final class SurfaceControl implements Parcelable {
		*/
		public static final int CAN_OCCLUDE_PRESENTATION = 0x00001000;

		/**
		* Indicates that the SurfaceControl should recover from buffer stuffing when
		* possible. This is the case when the SurfaceControl is a ViewRootImpl.
		* @hide
		*/
		public static final int RECOVERABLE_FROM_BUFFER_STUFFING = 0x00002000;

		/**
		* Surface creation flag: Creates a surface where color components are interpreted
		* as "non pre-multiplied" by their alpha channel. Of course this flag is
		@@ -4813,6 +4821,23 @@ public final class SurfaceControl implements Parcelable {
		nativeSetDesiredPresentTimeNanos(mNativeObject, desiredPresentTimeNanos);
		return this;
		}

		/**
		* Specifies that the SurfaceControl is a buffer producer that should recover from buffer
		* stuffing, meaning that the SurfaceControl is a ViewRootImpl.
		*
		* @hide
		*/
		@NonNull
		public Transaction setRecoverableFromBufferStuffing(@NonNull SurfaceControl sc) {
		if (bufferStuffingRecovery()) {
		checkPreconditions(sc);
		nativeSetFlags(mNativeObject, sc.mNativeObject, RECOVERABLE_FROM_BUFFER_STUFFING,
		RECOVERABLE_FROM_BUFFER_STUFFING);
		}
		return this;
		}

		/**
		* Writes the transaction to parcel, clearing the transaction as if it had been applied so
		* it can be used to store future transactions. It's the responsibility of the parcel

core/java/android/view/ViewRootImpl.java

+3 −0

Original line number	Diff line number	Diff line
		@@ -2757,6 +2757,9 @@ public final class ViewRootImpl implements ViewParent,
		// Only call transferFrom if the surface has changed to prevent inc the generation ID and
		// causing EGL resources to be recreated.
		mSurface.transferFrom(blastSurface);

		// Since the SurfaceControl is a VRI, indicate that it can recover from buffer stuffing.
		mTransaction.setRecoverableFromBufferStuffing(mSurfaceControl).applyAsyncUnsafe();
		}

		private void setBoundsLayerCrop(Transaction t) {

core/java/android/view/flags/view_flags.aconfig

+8 −0

Original line number	Diff line number	Diff line
		@@ -133,3 +133,11 @@ flag {
		bug: "333417898"
		is_fixed_read_only: true
		}

		flag {
		name: "buffer_stuffing_recovery"
		namespace: "window_surfaces"
		description: "Recover from buffer stuffing when SurfaceFlinger misses a frame"
		bug: "294922229"
		is_fixed_read_only: true
		}
		No newline at end of file