Merge "Fix possible races in vsync infrastructure." (a9daa164) · Commits · e / os / android_frameworks_base

core/java/android/view/Choreographer.java

+72 −7

Original line number	Diff line number	Diff line
		@@ -31,12 +31,20 @@ import android.util.Log;
		* This object is thread-safe. Other threads can add and remove listeners
		* or schedule work to occur at a later time on the UI thread.
		*
		* Ensuring thread-safety is a little tricky because the {@link DisplayEventReceiver}
		* can only be accessed from the UI thread so operations that touch the event receiver
		* are posted to the UI thread if needed.
		*
		* @hide
		*/
		public final class Choreographer extends Handler {
		private static final String TAG = "Choreographer";
		private static final boolean DEBUG = false;

		// Amount of time in ms to wait before actually disposing of the display event
		// receiver after all listeners have been removed.
		private static final long DISPOSE_RECEIVER_DELAY = 200;

		// The default amount of time in ms between animation frames.
		// When vsync is not enabled, we want to have some idea of how long we should
		// wait before posting the next animation message. It is important that the
		@@ -78,6 +86,8 @@ public final class Choreographer extends Handler {

		private static final int MSG_DO_ANIMATION = 0;
		private static final int MSG_DO_DRAW = 1;
		private static final int MSG_DO_SCHEDULE_VSYNC = 2;
		private static final int MSG_DO_DISPOSE_RECEIVER = 3;

		private final Object mLock = new Object();

		@@ -88,6 +98,7 @@ public final class Choreographer extends Handler {

		private boolean mAnimationScheduled;
		private boolean mDrawScheduled;
		private boolean mFrameDisplayEventReceiverNeeded;
		private FrameDisplayEventReceiver mFrameDisplayEventReceiver;
		private long mLastAnimationTime;
		private long mLastDrawTime;
		@@ -158,10 +169,21 @@ public final class Choreographer extends Handler {
		if (DEBUG) {
		Log.d(TAG, "Scheduling vsync for animation.");
		}
		if (mFrameDisplayEventReceiver == null) {
		mFrameDisplayEventReceiver = new FrameDisplayEventReceiver(mLooper);

		// If running on the Looper thread, then schedule the vsync immediately,
		// otherwise post a message to schedule the vsync from the UI thread
		// as soon as possible.
		if (!mFrameDisplayEventReceiverNeeded) {
		mFrameDisplayEventReceiverNeeded = true;
		if (mFrameDisplayEventReceiver != null) {
		removeMessages(MSG_DO_DISPOSE_RECEIVER);
		}
		}
		if (isRunningOnLooperThreadLocked()) {
		doScheduleVsyncLocked();
		} else {
		sendMessageAtFrontOfQueue(obtainMessage(MSG_DO_SCHEDULE_VSYNC));
		}
		mFrameDisplayEventReceiver.scheduleVsync();
		} else {
		final long now = SystemClock.uptimeMillis();
		final long nextAnimationTime = Math.max(mLastAnimationTime + sFrameDelay, now);
		@@ -224,6 +246,12 @@ public final class Choreographer extends Handler {
		case MSG_DO_DRAW:
		doDraw();
		break;
		case MSG_DO_SCHEDULE_VSYNC:
		doScheduleVsync();
		break;
		case MSG_DO_DISPOSE_RECEIVER:
		doDisposeReceiver();
		break;
		}
		}

		@@ -295,6 +323,30 @@ public final class Choreographer extends Handler {
		}
		}

		private void doScheduleVsync() {
		synchronized (mLock) {
		doScheduleVsyncLocked();
		}
		}

		private void doScheduleVsyncLocked() {
		if (mFrameDisplayEventReceiverNeeded && mAnimationScheduled) {
		if (mFrameDisplayEventReceiver == null) {
		mFrameDisplayEventReceiver = new FrameDisplayEventReceiver(mLooper);
		}
		mFrameDisplayEventReceiver.scheduleVsync();
		}
		}

		private void doDisposeReceiver() {
		synchronized (mLock) {
		if (!mFrameDisplayEventReceiverNeeded && mFrameDisplayEventReceiver != null) {
		mFrameDisplayEventReceiver.dispose();
		mFrameDisplayEventReceiver = null;
		}
		}
		}

		/**
		* Adds an animation listener.
		*
		@@ -386,7 +438,9 @@ public final class Choreographer extends Handler {

		if (mAnimationScheduled) {
		mAnimationScheduled = false;
		if (!USE_VSYNC) {
		if (USE_VSYNC) {
		removeMessages(MSG_DO_SCHEDULE_VSYNC);
		} else {
		removeMessages(MSG_DO_ANIMATION);
		}
		}
		@@ -398,13 +452,24 @@ public final class Choreographer extends Handler {
		}
		}

		// Post a message to dispose the display event receiver if we haven't needed
		// it again after a certain amount of time has elapsed. Another reason to
		// defer disposal is that it is possible for use to attempt to dispose the
		// receiver while handling a vsync event that it dispatched, which might
		// cause a few problems...
		if (mFrameDisplayEventReceiverNeeded) {
		mFrameDisplayEventReceiverNeeded = false;
		if (mFrameDisplayEventReceiver != null) {
		mFrameDisplayEventReceiver.dispose();
		mFrameDisplayEventReceiver = null;
		sendEmptyMessageDelayed(MSG_DO_DISPOSE_RECEIVER, DISPOSE_RECEIVER_DELAY);
		}
		}
		}
		}

		private boolean isRunningOnLooperThreadLocked() {
		return Looper.myLooper() == mLooper;
		}

		/**
		* Listens for animation frame timing events.
		*/

core/java/android/view/DisplayEventReceiver.java

+4 −0

Original line number	Diff line number	Diff line
		@@ -25,6 +25,10 @@ import android.util.Log;
		/**
		* Provides a low-level mechanism for an application to receive display events
		* such as vertical sync.
		*
		* The display event receive is NOT thread safe. Moreover, its methods must only
		* be called on the Looper thread to which it is attached.
		*
		* @hide
		*/
		public abstract class DisplayEventReceiver {

core/jni/android_view_DisplayEventReceiver.cpp

+13 −25

Original line number	Diff line number	Diff line
		@@ -59,21 +59,20 @@ private:
		sp<Looper> mLooper;
		DisplayEventReceiver mReceiver;
		bool mWaitingForVsync;
		bool mFdCallbackRegistered;
		};


		NativeDisplayEventReceiver::NativeDisplayEventReceiver(JNIEnv* env,
		jobject receiverObj, const sp<Looper>& looper) :
		mReceiverObjGlobal(env->NewGlobalRef(receiverObj)),
		mLooper(looper), mWaitingForVsync(false), mFdCallbackRegistered(false) {
		mLooper(looper), mWaitingForVsync(false) {
		ALOGV("receiver %p ~ Initializing input event receiver.", this);
		}

		NativeDisplayEventReceiver::~NativeDisplayEventReceiver() {
		ALOGV("receiver %p ~ Disposing display event receiver.", this);

		if (mFdCallbackRegistered) {
		if (!mReceiver.initCheck()) {
		mLooper->removeFd(mReceiver.getFd());
		}

		@@ -88,6 +87,11 @@ status_t NativeDisplayEventReceiver::initialize() {
		return result;
		}

		int rc = mLooper->addFd(mReceiver.getFd(), 0, ALOOPER_EVENT_INPUT,
		handleReceiveCallback, this);
		if (rc < 0) {
		return UNKNOWN_ERROR;
		}
		return OK;
		}

		@@ -113,15 +117,6 @@ status_t NativeDisplayEventReceiver::scheduleVsync() {
		return status;
		}

		if (!mFdCallbackRegistered) {
		int rc = mLooper->addFd(mReceiver.getFd(), 0, ALOOPER_EVENT_INPUT,
		handleReceiveCallback, this);
		if (rc < 0) {
		return UNKNOWN_ERROR;
		}
		mFdCallbackRegistered = true;
		}

		mWaitingForVsync = true;
		}
		return OK;
		@@ -133,7 +128,6 @@ int NativeDisplayEventReceiver::handleReceiveCallback(int receiveFd, int events,
		if (events & (ALOOPER_EVENT_ERROR \| ALOOPER_EVENT_HANGUP)) {
		ALOGE("Display event receiver pipe was closed or an error occurred. "
		"events=0x%x", events);
		r->mFdCallbackRegistered = false;
		return 0; // remove the callback
		}

		@@ -150,7 +144,7 @@ int NativeDisplayEventReceiver::handleReceiveCallback(int receiveFd, int events,
		DisplayEventReceiver::Event buf[EVENT_BUFFER_SIZE];
		ssize_t n;
		while ((n = r->mReceiver.getEvents(buf, EVENT_BUFFER_SIZE)) > 0) {
		ALOGV("receiver %p ~ Read %d events.", this, int(n));
		ALOGV("receiver %p ~ Read %d events.", data, int(n));
		while (n-- > 0) {
		if (buf[n].header.type == DisplayEventReceiver::DISPLAY_EVENT_VSYNC) {
		vsyncTimestamp = buf[n].header.timestamp;
		@@ -161,20 +155,20 @@ int NativeDisplayEventReceiver::handleReceiveCallback(int receiveFd, int events,
		}

		if (vsyncTimestamp < 0) {
		ALOGV("receiver %p ~ Woke up but there was no vsync pulse!", this);
		ALOGV("receiver %p ~ Woke up but there was no vsync pulse!", data);
		return 1; // keep the callback, did not obtain a vsync pulse
		}

		ALOGV("receiver %p ~ Vsync pulse: timestamp=%lld, count=%d",
		this, vsyncTimestamp, vsyncCount);
		data, vsyncTimestamp, vsyncCount);
		r->mWaitingForVsync = false;

		JNIEnv* env = AndroidRuntime::getJNIEnv();

		ALOGV("receiver %p ~ Invoking vsync handler.", this);
		ALOGV("receiver %p ~ Invoking vsync handler.", data);
		env->CallVoidMethod(r->mReceiverObjGlobal,
		gDisplayEventReceiverClassInfo.dispatchVsync, vsyncTimestamp, vsyncCount);
		ALOGV("receiver %p ~ Returned from vsync handler.", this);
		ALOGV("receiver %p ~ Returned from vsync handler.", data);

		if (env->ExceptionCheck()) {
		ALOGE("An exception occurred while dispatching a vsync event.");
		@@ -182,14 +176,8 @@ int NativeDisplayEventReceiver::handleReceiveCallback(int receiveFd, int events,
		env->ExceptionClear();
		}

		// Check whether dispatchVsync called scheduleVsync reentrantly and set mWaitingForVsync.
		// If so, keep the callback, otherwise remove it.
		if (r->mWaitingForVsync) {
		return 1; // keep the callback
		}
		r->mFdCallbackRegistered = false;
		return 0; // remove the callback
		}


		static jint nativeInit(JNIEnv* env, jclass clazz, jobject receiverObj,