Commit b29b6aac authored Aug 03, 2021 by Tony Huang

Fix split caused apps ANR

If mWindowDrawCountDown is set to non null when mReportNextDraw
is false, it won't get cleared in performingDraw.
If another draw occurs afterwards where mReportNextDraw is true,
but requestDrawWindow doesn't get called, an ANR will occur.
This is because performDraw will end up waiting forever since
mWindowDrawCountDown was previously set to non null,
but there will never be any calls reportDrawFinish to handle the
countDown.

We should only create latch and wait it when mReportNextDraw is
true.

Bug: 195262673
Test: Pass existing tests
Test: Drag and drop split divider quickly
Change-Id: I4ee81a41687c4f61a4828d4c61ba01abee795e89

parent cc3b202f

core/java/android/view/ViewRootImpl.java

+4 −1

Original line number	Original line	Diff line number	Diff line
	@@ -9931,7 +9931,10 @@ public final class ViewRootImpl implements ViewParent,
	if (!mUseMTRenderer) {		if (!mUseMTRenderer) {
	return;		return;
	}		}
			// Only wait if it will report next draw.
			if (mReportNextDraw) {
	mWindowDrawCountDown = new CountDownLatch(mWindowCallbacks.size());		mWindowDrawCountDown = new CountDownLatch(mWindowCallbacks.size());
			}
	for (int i = mWindowCallbacks.size() - 1; i >= 0; i--) {		for (int i = mWindowCallbacks.size() - 1; i >= 0; i--) {
	mWindowCallbacks.get(i).onRequestDraw(mReportNextDraw);		mWindowCallbacks.get(i).onRequestDraw(mReportNextDraw);
	}		}