Revert "MessageQueue: track tail of queue" (3a44b7d7) · Commits · e / os / android_frameworks_base

core/java/android/os/MessageQueue.java

+14 −186

Original line number	Diff line number	Diff line
		@@ -57,7 +57,6 @@ public final class MessageQueue {

		@UnsupportedAppUsage
		Message mMessages;
		private Message mLast;
		@UnsupportedAppUsage
		private final ArrayList<IdleHandler> mIdleHandlers = new ArrayList<IdleHandler>();
		private SparseArray<FileDescriptorRecord> mFileDescriptorRecords;
		@@ -67,10 +66,6 @@ public final class MessageQueue {
		// Indicates whether next() is blocked waiting in pollOnce() with a non-zero timeout.
		private boolean mBlocked;

		// Tracks the number of async message. We use this in enqueueMessage() to avoid searching the
		// queue for async messages when inserting a message at the tail.
		private int mAsyncMessageCount;

		// The next barrier token.
		// Barriers are indicated by messages with a null target whose arg1 field carries the token.
		@UnsupportedAppUsage
		@@ -369,21 +364,12 @@ public final class MessageQueue {
		mBlocked = false;
		if (prevMsg != null) {
		prevMsg.next = msg.next;
		if (prevMsg.next == null) {
		mLast = prevMsg;
		}
		} else {
		mMessages = msg.next;
		if (msg.next == null) {
		mLast = null;
		}
		}
		msg.next = null;
		if (DEBUG) Log.v(TAG, "Returning message: " + msg);
		msg.markInUse();
		if (msg.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		return msg;
		}
		} else {
		@@ -506,14 +492,6 @@ public final class MessageQueue {
		msg.when = when;
		msg.arg1 = token;

		if (Flags.messageQueueTailTracking() && mLast != null && mLast.when <= when) {
		/* Message goes to tail of list */
		mLast.next = msg;
		mLast = msg;
		msg.next = null;
		return token;
		}

		Message prev = null;
		Message p = mMessages;
		if (when != 0) {
		@@ -522,12 +500,6 @@ public final class MessageQueue {
		p = p.next;
		}
		}

		if (p == null) {
		/* We reached the tail of the list, or list is empty. */
		mLast = msg;
		}

		if (prev != null) { // invariant: p == prev.next
		msg.next = p;
		prev.next = msg;
		@@ -568,15 +540,9 @@ public final class MessageQueue {
		final boolean needWake;
		if (prev != null) {
		prev.next = p.next;
		if (prev.next == null) {
		mLast = prev;
		}
		needWake = false;
		} else {
		mMessages = p.next;
		if (mMessages == null) {
		mLast = null;
		}
		needWake = mMessages == null \|\| mMessages.target != null;
		}
		p.recycleUnchecked();
		@@ -616,42 +582,10 @@ public final class MessageQueue {
		msg.next = p;
		mMessages = msg;
		needWake = mBlocked;
		if (p == null) {
		mLast = mMessages;
		}
		} else {
		// Message is to be inserted at tail or middle of queue. Usually we don't have to
		// wake up the event queue unless there is a barrier at the head of the queue and
		// the message is the earliest asynchronous message in the queue.
		//
		// For readability, we split this portion of the function into two blocks based on
		// whether tail tracking is enabled. This has a minor implication for the case
		// where tail tracking is disabled. See the comment below.
		if (Flags.messageQueueTailTracking()) {
		needWake = mBlocked && p.target == null && msg.isAsynchronous()
		&& mAsyncMessageCount == 0;
		if (when >= mLast.when) {
		msg.next = null;
		mLast.next = msg;
		mLast = msg;
		} else {
		// Inserted within the middle of the queue.
		Message prev;
		for (;;) {
		prev = p;
		p = p.next;
		if (p == null \|\| when < p.when) {
		break;
		}
		}
		if (p == null) {
		/* Inserting at tail of queue */
		mLast = msg;
		}
		msg.next = p; // invariant: p == prev.next
		prev.next = msg;
		}
		} else {
		// Inserted within the middle of the queue. Usually we don't have to wake
		// up the event queue unless there is a barrier at the head of the queue
		// and the message is the earliest asynchronous message in the queue.
		needWake = mBlocked && p.target == null && msg.isAsynchronous();
		Message prev;
		for (;;) {
		@@ -666,27 +600,6 @@ public final class MessageQueue {
		}
		msg.next = p; // invariant: p == prev.next
		prev.next = msg;

		/*
		* If this block is executing then we have a build without tail tracking -
		* specifically: Flags.messageQueueTailTracking() == false. This is determined
		* at build time so the flag won't change on us during runtime.
		*
		* Since we don't want to pepper the code with extra checks, we only check
		* for tail tracking when we might use mLast. Otherwise, we continue to update
		* mLast as the tail of the list.
		*
		* In this case however we are not maintaining mLast correctly. Since we never
		* use it, this is fine. However, we run the risk of leaking a reference.
		* So set mLast to null in this case to avoid any Message leaks. The other
		* sites will never use the value so we are safe against null pointer derefs.
		*/
		mLast = null;
		}
		}

		if (msg.isAsynchronous()) {
		mAsyncMessageCount++;
		}

		// We can assume mPtr != 0 because mQuitting is false.
		@@ -779,17 +692,10 @@ public final class MessageQueue {
		&& (object == null \|\| p.obj == object)) {
		Message n = p.next;
		mMessages = n;
		if (p.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		p.recycleUnchecked();
		p = n;
		}

		if (p == null) {
		mLast = mMessages;
		}

		// Remove all messages after front.
		while (p != null) {
		Message n = p.next;
		@@ -797,14 +703,8 @@ public final class MessageQueue {
		if (n.target == h && n.what == what
		&& (object == null \|\| n.obj == object)) {
		Message nn = n.next;
		if (n.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		n.recycleUnchecked();
		p.next = nn;
		if (p.next == null) {
		mLast = p;
		}
		continue;
		}
		}
		@@ -826,17 +726,10 @@ public final class MessageQueue {
		&& (object == null \|\| object.equals(p.obj))) {
		Message n = p.next;
		mMessages = n;
		if (p.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		p.recycleUnchecked();
		p = n;
		}

		if (p == null) {
		mLast = mMessages;
		}

		// Remove all messages after front.
		while (p != null) {
		Message n = p.next;
		@@ -844,14 +737,8 @@ public final class MessageQueue {
		if (n.target == h && n.what == what
		&& (object == null \|\| object.equals(n.obj))) {
		Message nn = n.next;
		if (n.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		n.recycleUnchecked();
		p.next = nn;
		if (p.next == null) {
		mLast = p;
		}
		continue;
		}
		}
		@@ -873,17 +760,10 @@ public final class MessageQueue {
		&& (object == null \|\| p.obj == object)) {
		Message n = p.next;
		mMessages = n;
		if (p.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		p.recycleUnchecked();
		p = n;
		}

		if (p == null) {
		mLast = mMessages;
		}

		// Remove all messages after front.
		while (p != null) {
		Message n = p.next;
		@@ -891,14 +771,8 @@ public final class MessageQueue {
		if (n.target == h && n.callback == r
		&& (object == null \|\| n.obj == object)) {
		Message nn = n.next;
		if (n.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		n.recycleUnchecked();
		p.next = nn;
		if (p.next == null) {
		mLast = p;
		}
		continue;
		}
		}
		@@ -920,17 +794,10 @@ public final class MessageQueue {
		&& (object == null \|\| object.equals(p.obj))) {
		Message n = p.next;
		mMessages = n;
		if (p.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		p.recycleUnchecked();
		p = n;
		}

		if (p == null) {
		mLast = mMessages;
		}

		// Remove all messages after front.
		while (p != null) {
		Message n = p.next;
		@@ -938,14 +805,8 @@ public final class MessageQueue {
		if (n.target == h && n.callback == r
		&& (object == null \|\| object.equals(n.obj))) {
		Message nn = n.next;
		if (n.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		n.recycleUnchecked();
		p.next = nn;
		if (p.next == null) {
		mLast = p;
		}
		continue;
		}
		}
		@@ -968,31 +829,18 @@ public final class MessageQueue {
		&& (object == null \|\| p.obj == object)) {
		Message n = p.next;
		mMessages = n;
		if (p.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		p.recycleUnchecked();
		p = n;
		}

		if (p == null) {
		mLast = mMessages;
		}

		// Remove all messages after front.
		while (p != null) {
		Message n = p.next;
		if (n != null) {
		if (n.target == h && (object == null \|\| n.obj == object)) {
		Message nn = n.next;
		if (n.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		n.recycleUnchecked();
		p.next = nn;
		if (p.next == null) {
		mLast = p;
		}
		continue;
		}
		}
		@@ -1014,31 +862,18 @@ public final class MessageQueue {
		&& (object == null \|\| object.equals(p.obj))) {
		Message n = p.next;
		mMessages = n;
		if (p.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		p.recycleUnchecked();
		p = n;
		}

		if (p == null) {
		mLast = mMessages;
		}

		// Remove all messages after front.
		while (p != null) {
		Message n = p.next;
		if (n != null) {
		if (n.target == h && (object == null \|\| object.equals(n.obj))) {
		Message nn = n.next;
		if (n.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		n.recycleUnchecked();
		p.next = nn;
		if (p.next == null) {
		mLast = p;
		}
		continue;
		}
		}
		@@ -1055,8 +890,6 @@ public final class MessageQueue {
		p = n;
		}
		mMessages = null;
		mLast = null;
		mAsyncMessageCount = 0;
		}

		private void removeAllFutureMessagesLocked() {
		@@ -1078,14 +911,9 @@ public final class MessageQueue {
		p = n;
		}
		p.next = null;
		mLast = p;

		do {
		p = n;
		n = p.next;
		if (p.isAsynchronous()) {
		mAsyncMessageCount--;
		}
		p.recycleUnchecked();
		} while (n != null);
		}