Remove flag message_queue_tail_tracking (8e985f5a) · Commits · e / os / android_frameworks_base

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

+11 −43

Original line number	Diff line number	Diff line
		@@ -1176,7 +1176,7 @@ public final class MessageQueue {
		msg.arg1 = token;
		incAndTraceMessageCount(msg, when);

		if (Flags.messageQueueTailTracking() && mLast != null && mLast.when <= when) {
		if (mLast != null && mLast.when <= when) {
		/* Message goes to tail of list */
		mLast.next = msg;
		mLast = msg;
		@@ -1359,7 +1359,6 @@ public final class MessageQueue {
		// 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()) {
		if (when >= mLast.when) {
		needWake = needWake && mAsyncMessageCount == 0;
		msg.next = null;
		@@ -1385,37 +1384,6 @@ public final class MessageQueue {
		msg.next = p; // invariant: p == prev.next
		prev.next = msg;
		}
		} else {
		Message prev;
		for (;;) {
		prev = p;
		p = p.next;
		if (p == null \|\| when < p.when) {
		break;
		}
		if (needWake && p.isAsynchronous()) {
		needWake = false;
		}
		}
		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()) {

core/java/android/os/LegacyMessageQueue/MessageQueue.java

+11 −46

Original line number	Diff line number	Diff line
		@@ -560,7 +560,7 @@ public final class MessageQueue {
		msg.when = when;
		msg.arg1 = token;

		if (Flags.messageQueueTailTracking() && mLast != null && mLast.when <= when) {
		if (mLast != null && mLast.when <= when) {
		/* Message goes to tail of list */
		mLast.next = msg;
		mLast = msg;
		@@ -679,10 +679,6 @@ public final class MessageQueue {
		// the message is the earliest asynchronous message in the queue.
		needWake = mBlocked && p.target == null && msg.isAsynchronous();

		// 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()) {
		if (when >= mLast.when) {
		needWake = needWake && mAsyncMessageCount == 0;
		msg.next = null;
		@@ -708,37 +704,6 @@ public final class MessageQueue {
		msg.next = p; // invariant: p == prev.next
		prev.next = msg;
		}
		} else {
		Message prev;
		for (;;) {
		prev = p;
		p = p.next;
		if (p == null \|\| when < p.when) {
		break;
		}
		if (needWake && p.isAsynchronous()) {
		needWake = false;
		}
		}
		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()) {

core/java/android/os/flags.aconfig

+0 −8

Original line number	Diff line number	Diff line
		@@ -310,14 +310,6 @@ flag {
		is_exported: true
		}

		flag {
		name: "message_queue_tail_tracking"
		namespace: "system_performance"
		description: "track tail of message queue."
		bug: "305311707"
		is_fixed_read_only: true
		}

		flag {
		name: "message_queue_testability"
		namespace: "system_performance"