Don't call nativePollOnce unnecessarily (d07f0cd9) · Commits · e / os / android_frameworks_base

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

+25 −6

Original line number	Diff line number	Diff line
		@@ -98,6 +98,7 @@ public final class MessageQueue {
		@UnsupportedAppUsage
		private final ArrayList<IdleHandler> mIdleHandlers = new ArrayList<IdleHandler>();
		private SparseArray<FileDescriptorRecord> mFileDescriptorRecords;
		private volatile boolean mHasFileDescriptorRecords;
		private IdleHandler[] mPendingIdleHandlers;
		private boolean mQuitting;

		@@ -584,6 +585,16 @@ public final class MessageQueue {

		setFileDescriptorEvents(fdNum, 0);
		}

		// Indicate to maybePollOnce() if we have file descriptor records that
		// need to be polled for events.
		// We write this volatile field here and read it from the worker thread.
		// Adding an FD on a client thread and polling for events on the worker thread are
		// inherently racy. If the worker thread skips polling because it thinks there are
		// no FDs to watch and there is a Message to handle, then the worker will still
		// poll for the same events the next time. Events won't be missed, they'll just be
		// interleaved with Message handling in undefined ways.
		mHasFileDescriptorRecords = mFileDescriptorRecords.size() > 0;
		}

		// Called from native code.
		@@ -853,9 +864,18 @@ public final class MessageQueue {
		}
		}

		private void maybePollOnce(int nextPollTimeoutMillis) {
		if (!Flags.messageQueueNativePollOnceAndForAll()) {
		// If nativePollOnce optimization is not in effect, poll unconditionally.
		nativePollOnce(mPtr, nextPollTimeoutMillis);
		} else if (nextPollTimeoutMillis != 0 \|\| mHasFileDescriptorRecords \|\| getQuitting()) {
		// We need to wait for the next message, or we need to poll for file descriptor events.
		nativePollOnce(mPtr, nextPollTimeoutMillis);
		}
		}

		private Message nextConcurrent() {
		final long ptr = mPtr;
		if (ptr == 0) {
		if (mPtr == 0) {
		return null;
		}

		@@ -867,7 +887,7 @@ public final class MessageQueue {
		}

		mMessageDirectlyQueued = false;
		nativePollOnce(ptr, mNextPollTimeoutMillis);
		maybePollOnce(mNextPollTimeoutMillis);

		Message msg = nextMessage(false, false);
		if (msg != null) {
		@@ -934,8 +954,7 @@ public final class MessageQueue {
		// Return here if the message loop has already quit and been disposed.
		// This can happen if the application tries to restart a looper after quit
		// which is not supported.
		final long ptr = mPtr;
		if (ptr == 0) {
		if (mPtr == 0) {
		return null;
		}

		@@ -946,7 +965,7 @@ public final class MessageQueue {
		Binder.flushPendingCommands();
		}

		nativePollOnce(ptr, nextPollTimeoutMillis);
		maybePollOnce(nextPollTimeoutMillis);

		synchronized (this) {
		// Try to retrieve the next message. Return if found.

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

+22 −1

Original line number	Diff line number	Diff line
		@@ -438,6 +438,7 @@ public final class MessageQueue {
		private final Object mFileDescriptorRecordsLock = new Object();
		@GuardedBy("mFileDescriptorRecordsLock")
		private SparseArray<FileDescriptorRecord> mFileDescriptorRecords;
		private volatile boolean mHasFileDescriptorRecords;

		// The next barrier token.
		// Barriers are indicated by messages with a null target whose arg1 field carries the token.
		@@ -885,6 +886,16 @@ public final class MessageQueue {
		}
		}

		private void maybePollOnce(int nextPollTimeoutMillis) {
		if (!Flags.messageQueueNativePollOnceAndForAll()) {
		// If nativePollOnce optimization is not in effect, poll unconditionally.
		nativePollOnce(mPtr, nextPollTimeoutMillis);
		} else if (nextPollTimeoutMillis != 0 \|\| mHasFileDescriptorRecords \|\| getQuitting()) {
		// We need to wait for the next message, or we need to poll for file descriptor events.
		nativePollOnce(mPtr, nextPollTimeoutMillis);
		}
		}

		Message next() {
		final long ptr = mPtr;
		if (ptr == 0) {
		@@ -899,7 +910,7 @@ public final class MessageQueue {
		}

		mMessageDirectlyQueued = false;
		nativePollOnce(ptr, mNextPollTimeoutMillis);
		maybePollOnce(mNextPollTimeoutMillis);

		Message msg = nextMessage(false, false);
		if (msg != null) {
		@@ -1750,6 +1761,16 @@ public final class MessageQueue {
		mFileDescriptorRecords.removeAt(index);
		setFileDescriptorEvents(fdNum, 0);
		}

		// Indicate to maybePollOnce() if we have file descriptor records that
		// need to be polled for events.
		// We write this volatile field here and read it from the worker thread.
		// Adding an FD on a client thread and polling for events on the worker thread are
		// inherently racy. If the worker thread skips polling because it thinks there are
		// no FDs to watch and there is a Message to handle, then the worker will still
		// poll for the same events the next time. Events won't be missed, they'll just be
		// interleaved with Message handling in undefined ways.
		mHasFileDescriptorRecords = mFileDescriptorRecords.size() > 0;
		}

		// Called from native code.

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

+22 −1

Original line number	Diff line number	Diff line
		@@ -71,6 +71,7 @@ public final class MessageQueue {
		@UnsupportedAppUsage
		private final ArrayList<IdleHandler> mIdleHandlers = new ArrayList<IdleHandler>();
		private SparseArray<FileDescriptorRecord> mFileDescriptorRecords;
		private volatile boolean mHasFileDescriptorRecords;
		private IdleHandler[] mPendingIdleHandlers;
		private boolean mQuitting;

		@@ -326,6 +327,16 @@ public final class MessageQueue {
		mFileDescriptorRecords.removeAt(index);
		nativeSetFileDescriptorEvents(mPtr, fdNum, 0);
		}

		// Indicate to maybePollOnce() if we have file descriptor records that
		// need to be polled for events.
		// We write this volatile field here and read it from the worker thread.
		// Adding an FD on a client thread and polling for events on the worker thread are
		// inherently racy. If the worker thread skips polling because it thinks there are
		// no FDs to watch and there is a Message to handle, then the worker will still
		// poll for the same events the next time. Events won't be missed, they'll just be
		// interleaved with Message handling in undefined ways.
		mHasFileDescriptorRecords = mFileDescriptorRecords.size() > 0;
		}

		// Called from native code.
		@@ -380,6 +391,16 @@ public final class MessageQueue {

		private static final AtomicLong mMessagesDelivered = new AtomicLong();

		private void maybePollOnce(int nextPollTimeoutMillis) {
		if (!Flags.messageQueueNativePollOnceAndForAll()) {
		// If nativePollOnce optimization is not in effect, poll unconditionally.
		nativePollOnce(mPtr, nextPollTimeoutMillis);
		} else if (nextPollTimeoutMillis != 0 \|\| mHasFileDescriptorRecords) {
		// We need to wait for the next message, or we need to poll for file descriptor events.
		nativePollOnce(mPtr, nextPollTimeoutMillis);
		}
		}

		@UnsupportedAppUsage
		Message next() {
		// Return here if the message loop has already quit and been disposed.
		@@ -397,7 +418,7 @@ public final class MessageQueue {
		Binder.flushPendingCommands();
		}

		nativePollOnce(ptr, nextPollTimeoutMillis);
		maybePollOnce(nextPollTimeoutMillis);

		synchronized (this) {
		// Try to retrieve the next message. Return if found.

core/java/android/os/flags.aconfig

+8 −0

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

		flag {
		name: "message_queue_native_poll_once_and_for_all"
		namespace: "system_performance"
		description: "Don't call nativePollOnce unnecessarily."
		bug: "410218466"
		is_fixed_read_only: false
		}

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