Prevent race between nativeWake and dispose, and potential deadlock (3743222f) · Commits · e / os / android_frameworks_base

core/java/android/os/CombinedMessageQueue/MessageQueue.java

+105 −39

Original line number	Diff line number	Diff line
		@@ -73,6 +73,16 @@ public final class MessageQueue {
		@UnsupportedAppUsage
		private final boolean mQuitAllowed;

		/**
		* Used by all native methods.
		*
		* <p>In legacy mode, usage of this field (directly, or indirectly via native method
		* invocations) must be guarded with the lock.
		*
		* <p>In concurrent mode, the Looper thread may access freely, but other threads must first call
		* {@link #incrementMptrRefs()}, check the result, and if true then access the native
		* object, followed by a call to {@link #decrementMptrRefs()}.
		*/
		@UnsupportedAppUsage
		@SuppressWarnings("unused")
		private long mPtr; // used by native code
		@@ -99,6 +109,7 @@ public final class MessageQueue {
		private int mAsyncMessageCount;

		private final AtomicLong mMessageCount = new AtomicLong();
		private final Thread mLooperThread;
		private final String mThreadName;
		private final long mTid;

		@@ -148,7 +159,8 @@ public final class MessageQueue {
		mUseConcurrent = sIsProcessAllowedToUseConcurrent;
		mQuitAllowed = quitAllowed;
		mPtr = nativeInit();
		mThreadName = Thread.currentThread().getName();
		mLooperThread = Thread.currentThread();
		mThreadName = mLooperThread.getName();
		mTid = Process.myTid();
		}

		@@ -402,15 +414,15 @@ public final class MessageQueue {

		private boolean isPollingConcurrent() {
		// If the loop is quitting then it must not be idling.
		if (!incrementQuittingState()) {
		return false;
		}
		if (incrementMptrRefs()) {
		try {
		return nativeIsPolling(mPtr);
		} finally {
		decrementQuittingState();
		decrementMptrRefs();
		}
		}
		return false;
		}

		private boolean isPollingLegacy() {
		synchronized (this) {
		@@ -565,11 +577,12 @@ public final class MessageQueue {
		record.mEvents = events;
		record.mSeq += 1;
		}
		nativeSetFileDescriptorEvents(mPtr, fdNum, events);
		setFileDescriptorEvents(fdNum, events);
		} else if (record != null) {
		record.mEvents = 0;
		mFileDescriptorRecords.removeAt(index);
		nativeSetFileDescriptorEvents(mPtr, fdNum, 0);

		setFileDescriptorEvents(fdNum, 0);
		}
		}

		@@ -786,8 +799,12 @@ public final class MessageQueue {
		*/
		StateNode nextOp = sStackStateActive;
		if (found == null) {
		if (next == null) {
		/* No message to deliver, sleep indefinitely */
		if (getQuitting()) {
		mNextPollTimeoutMillis = 0;
		// State change will be Active->Active, so can immediately return here.
		return null;
		} else if (next == null) {
		/* No message to deliver, sleep indefinitely, unless quitting */
		mNextPollTimeoutMillis = -1;
		nextOp = sStackStateParked;
		if (DEBUG) {
		@@ -1053,11 +1070,8 @@ public final class MessageQueue {
		}

		if (mUseConcurrent) {
		if (!incrementQuittingState()) {
		return;
		}
		if (incrementMptrRefsAndSetQuitting()) {
		try {
		if (setQuitting()) {
		if (safe) {
		removeAllFutureMessages();
		} else {
		@@ -1066,9 +1080,9 @@ public final class MessageQueue {

		// We can assume mPtr != 0 while we hold a ref on our quitting state
		nativeWake(mPtr);
		}
		} finally {
		decrementQuittingState();
		decrementMptrRefs();
		}
		}
		} else {
		synchronized (this) {
		@@ -1232,7 +1246,7 @@ public final class MessageQueue {
		Message m = first.mMessage;
		if (m.target == null && m.arg1 == token) {
		/* Wake up next() in case it was sleeping on this barrier. */
		nativeWake(mPtr);
		concurrentWake();
		}
		} else if (!removed) {
		throw new IllegalStateException("The specified message queue synchronization "
		@@ -2662,45 +2676,97 @@ public final class MessageQueue {
		}

		// Use MSB to indicate quitting state. Lower 63 bits hold ref count.
		private static final long QUITTING_MASK = ~(-1L >>> 1);
		private static final long QUITTING_MASK = 1L << 63;

		private boolean incrementQuittingState() {
		long oldVal = (long)sQuittingRefCount.getAndAdd(this, 1);
		/**
		* Increment the mPtr ref count.
		*
		* If this method returns true then the caller may use mPtr until they call
		* {@link #decrementMptrRefs()}.
		* If this method returns false then the caller must not use mPtr, and must
		* instead assume that the MessageQueue is quitting or has already quit and
		* act accordingly.
		*/
		private boolean incrementMptrRefs() {
		while (true) {
		final long oldVal = mQuittingRefCountValue;
		if ((oldVal & QUITTING_MASK) != 0) {
		// If we're quitting we need to drop our ref and indicate to the caller
		sQuittingRefCount.getAndAdd(this, -1);
		// If we're quitting then we're not allowed to increment the ref count.
		return false;
		}
		if (sQuittingRefCount.compareAndSet(this, oldVal, oldVal + 1)) {
		// Successfully incremented the ref count without quitting.
		return true;
		}
		}
		}

		private void decrementQuittingState() {
		/**
		* Decrement the mPtr ref count.
		*
		* Call after {@link #incrementMptrRefs()} to release the ref on mPtr.
		*/
		private void decrementMptrRefs() {
		long oldVal = (long)sQuittingRefCount.getAndAdd(this, -1);
		// If quitting and we were the last ref, wake up looper thread
		if ((oldVal & QUITTING_MASK) != 0 && (oldVal & ~QUITTING_MASK) == 1L) {
		if (oldVal - 1 == QUITTING_MASK) {
		LockSupport.unpark(mLooperThread);
		}
		}

		private boolean setQuitting() {
		long oldVal = (long)sQuittingRefCount.getAndBitwiseOr(this, QUITTING_MASK);
		private boolean incrementMptrRefsAndSetQuitting() {
		while (true) {
		final long oldVal = mQuittingRefCountValue;
		if ((oldVal & QUITTING_MASK) != 0) {
		// If we're quitting then we're not allowed to increment the ref count.
		return false;
		}
		if (sQuittingRefCount.compareAndSet(this, oldVal, (oldVal + 1) \| QUITTING_MASK)) {
		// Successfully incremented the ref count and set quitting.
		return true;
		}
		}
		}

		/**
		* Wake the looper thread.
		*
		* {@link #nativeWake(long)} may be called directly only by the looper thread.
		* Otherwise, call this method to ensure safe access to mPtr.
		*/
		private void concurrentWake() {
		if (incrementMptrRefs()) {
		try {
		nativeWake(mPtr);
		} finally {
		decrementMptrRefs();
		}
		}
		}

		private void setFileDescriptorEvents(int fdNum, int events) {
		if (mUseConcurrent) {
		if (incrementMptrRefs()) {
		try {
		nativeSetFileDescriptorEvents(mPtr, fdNum, events);
		} finally {
		decrementMptrRefs();
		}
		}
		} else {
		nativeSetFileDescriptorEvents(mPtr, fdNum, events);
		}
		}

		private boolean getQuitting() {
		return (mQuittingRefCountValue & QUITTING_MASK) != 0;
		}

		private volatile Thread mLooperThread = null;
		// Must only be called from looper thread
		private boolean checkQuittingAndWaitForRefsToDrop() {
		if (!getQuitting()) {
		return false;
		}
		mLooperThread = Thread.currentThread();
		boolean wasInterrupted = false;
		try {
		while ((mQuittingRefCountValue & ~QUITTING_MASK) != 0) {
		@@ -2903,7 +2969,7 @@ public final class MessageQueue {
		if (sState.compareAndSet(this, old, node)) {
		if (inactive) {
		if (wakeNeeded) {
		nativeWake(mPtr);
		concurrentWake();
		} else {
		mMessageCounts.incrementQueued();
		}
		@@ -2956,7 +3022,7 @@ public final class MessageQueue {
		p.mMessage.recycleUnchecked();
		decAndTraceMessageCount();
		if (mMessageCounts.incrementCancelled()) {
		nativeWake(mPtr);
		concurrentWake();
		}
		}
		} else {

core/java/android/os/ConcurrentMessageQueue/MessageQueue.java

+94 −41

Original line number	Diff line number	Diff line
		@@ -242,39 +242,88 @@ public final class MessageQueue {
		}

		// Use MSB to indicate quitting state. Lower 63 bits hold ref count.
		private static final long QUITTING_MASK = ~(-1L >>> 1);
		private static final long QUITTING_MASK = 1L << 63;

		private boolean incrementQuittingState() {
		long oldVal = (long)sQuittingRefCount.getAndAdd(this, 1);
		/**
		* Increment the mPtr ref count.
		*
		* If this method returns true then the caller may use mPtr until they call
		* {@link #decrementMptrRefs()}.
		* If this method returns false then the caller must not use mPtr, and must
		* instead assume that the MessageQueue is quitting or has already quit and
		* act accordingly.
		*/
		private boolean incrementMptrRefs() {
		while (true) {
		final long oldVal = mQuittingRefCountValue;
		if ((oldVal & QUITTING_MASK) != 0) {
		// If we're quitting we need to drop our ref and indicate to the caller
		sQuittingRefCount.getAndAdd(this, -1);
		// If we're quitting then we're not allowed to increment the ref count.
		return false;
		}
		if (sQuittingRefCount.compareAndSet(this, oldVal, oldVal + 1)) {
		// Successfully incremented the ref count without quitting.
		return true;
		}
		}
		}

		private void decrementQuittingState() {
		/**
		* Decrement the mPtr ref count.
		*
		* Call after {@link #incrementMptrRefs()} to release the ref on mPtr.
		*/
		private void decrementMptrRefs() {
		long oldVal = (long)sQuittingRefCount.getAndAdd(this, -1);
		// If quitting and we were the last ref, wake up looper thread
		if ((oldVal & QUITTING_MASK) != 0 && (oldVal & ~QUITTING_MASK) == 1L) {
		if (oldVal - 1 == QUITTING_MASK) {
		LockSupport.unpark(mLooperThread);
		}
		}

		private boolean setQuitting() {
		long oldVal = (long)sQuittingRefCount.getAndBitwiseOr(this, QUITTING_MASK);
		private boolean incrementMptrRefsAndSetQuitting() {
		while (true) {
		final long oldVal = mQuittingRefCountValue;
		if ((oldVal & QUITTING_MASK) != 0) {
		// If we're quitting then we're not allowed to increment the ref count.
		return false;
		}
		if (sQuittingRefCount.compareAndSet(this, oldVal, (oldVal + 1) \| QUITTING_MASK)) {
		// Successfully incremented the ref count and set quitting.
		return true;
		}
		}
		}

		/**
		* Wake the looper thread.
		*
		* {@link #nativeWake(long)} may be called directly only by the looper thread.
		* Otherwise, call this method to ensure safe access to mPtr.
		*/
		private void concurrentWake() {
		if (incrementMptrRefs()) {
		try {
		nativeWake(mPtr);
		} finally {
		decrementMptrRefs();
		}
		}
		}

		private void setFileDescriptorEvents(int fdNum, int events) {
		if (incrementMptrRefs()) {
		try {
		nativeSetFileDescriptorEvents(mPtr, fdNum, events);
		} finally {
		decrementMptrRefs();
		}
		}
		}

		private boolean getQuitting() {
		return (mQuittingRefCountValue & QUITTING_MASK) != 0;
		}

		private volatile Thread mLooperThread = null;
		// Must only be called from looper thread
		private boolean checkQuittingAndWaitForRefsToDrop() {
		if (!getQuitting()) {
		@@ -379,6 +428,7 @@ public final class MessageQueue {
		}

		private final MessageCounts mMessageCounts = new MessageCounts();
		private final Thread mLooperThread;

		private final Object mIdleHandlersLock = new Object();
		@GuardedBy("mIdleHandlersLock")
		@@ -421,6 +471,7 @@ public final class MessageQueue {
		MessageQueue(boolean quitAllowed) {
		mQuitAllowed = quitAllowed;
		mPtr = nativeInit();
		mLooperThread = Thread.currentThread();
		}

		@android.ravenwood.annotation.RavenwoodReplace
		@@ -565,15 +616,15 @@ public final class MessageQueue {
		*/
		public boolean isPolling() {
		// If the loop is quitting then it must not be idling.
		if (!incrementQuittingState()) {
		return false;
		}
		if (incrementMptrRefs()) {
		try {
		return nativeIsPolling(mPtr);
		} finally {
		decrementQuittingState();
		decrementMptrRefs();
		}
		}
		return false;
		}

		/* Helper to choose the correct queue to insert into. */
		private void insertIntoPriorityQueue(MessageNode msgNode) {
		@@ -778,7 +829,11 @@ public final class MessageQueue {
		*/
		StateNode nextOp = sStackStateActive;
		if (found == null) {
		if (next == null) {
		if (getQuitting()) {
		mNextPollTimeoutMillis = 0;
		// State change will be Active->Active, so can immediately return here.
		return null;
		} else if (next == null) {
		/* No message to deliver, sleep indefinitely */
		mNextPollTimeoutMillis = -1;
		nextOp = sStackStateParked;
		@@ -911,11 +966,10 @@ public final class MessageQueue {
		throw new IllegalStateException("Main thread not allowed to quit.");
		}

		if (!incrementQuittingState()) {
		if (!incrementMptrRefsAndSetQuitting()) {
		return;
		}
		try {
		if (setQuitting()) {
		if (safe) {
		removeAllFutureMessages();
		} else {
		@@ -924,9 +978,8 @@ public final class MessageQueue {

		// We can assume mPtr != 0 while we hold a ref on our quitting state
		nativeWake(mPtr);
		}
		} finally {
		decrementQuittingState();
		decrementMptrRefs();
		}
		}

		@@ -1027,7 +1080,7 @@ public final class MessageQueue {
		if (sState.compareAndSet(this, old, node)) {
		if (inactive) {
		if (wakeNeeded) {
		nativeWake(mPtr);
		concurrentWake();
		} else {
		mMessageCounts.incrementQueued();
		}
		@@ -1128,7 +1181,7 @@ public final class MessageQueue {
		Message m = first.mMessage;
		if (m.target == null && m.arg1 == token) {
		/* Wake up next() in case it was sleeping on this barrier. */
		nativeWake(mPtr);
		concurrentWake();
		}
		} else if (!removed) {
		throw new IllegalStateException("The specified message queue synchronization "
		@@ -1251,7 +1304,7 @@ public final class MessageQueue {
		if (p.removeFromStack()) {
		p.mMessage.recycleUnchecked();
		if (mMessageCounts.incrementCancelled()) {
		nativeWake(mPtr);
		concurrentWake();
		}
		}
		} else {
		@@ -1691,11 +1744,11 @@ public final class MessageQueue {
		record.mEvents = events;
		record.mSeq += 1;
		}
		nativeSetFileDescriptorEvents(mPtr, fdNum, events);
		setFileDescriptorEvents(fdNum, events);
		} else if (record != null) {
		record.mEvents = 0;
		mFileDescriptorRecords.removeAt(index);
		nativeSetFileDescriptorEvents(mPtr, fdNum, 0);
		setFileDescriptorEvents(fdNum, 0);
		}
		}