commit acf90acf137f236db7cf6df8d7c67228ec2c131b
author dooyoung.hwang <dooyoung.hwang@lge.com> Thu Dec 22 20:04:20 2016 +0900
committer Adrian Roos <roosa@google.com> Wed Dec 28 15:34:23 2016 -0800
tree 65903fa979dcd116960502e734849212ed1d9a85
parent 2f157c421a9fa15660b8f1bc0c64b1ebb45fa64a

QS - Fix race condition in accessibility

When users try to open panel, initialization of accessibility is called
in Main Thread by this callstack.

at android.view.ViewGroup.buildOrderedChildList
at android.view.View.populateAccessibilityNodeInfoDrawingOrderInParent
at android.view.View.onInitializeAccessibilityNodeInfoInternal
at android.view.View.onInitializeAccessibilityNodeInfo
at android.view.View.createAccessibilityNodeInfoInternal
at android.view.View.createAccessibilityNodeInfo
at android.view.accessibility.AccessibilityRecord.setSource
...
at android.view.View.setFlags
at android.view.View.setVisibility
at com.android.systemui.qs.QSContainer.updateQsState
at com.android.systemui.qs.QSContainer.setExpanded
at com.android.systemui.statusbar.phone.NotificationPanelView.updateQsState

And another initialization is tried in QSTileHost Thread by this callstack.

at android.view.ViewGroup.buildOrderedChildList
at android.view.View.populateAccessibilityNodeInfoDrawingOrderInParent
at android.view.View.onInitializeAccessibilityNodeInfoInternal
at android.view.ViewGroup.onInitializeAccessibilityNodeInfoInternal
at android.view.View.onInitializeAccessibilityNodeInfo
at android.view.View.createAccessibilityNodeInfoInternal
at android.view.View.createAccessibilityNodeInfo
at android.view.accessibility.AccessibilityRecord.setSource
...
at android.view.View.announceForAccessibility
at com.android.systemui.qs.QSPanel.onAnnouncementRequested
at com.android.systemui.qs.QSTile.handleStateChanged

This race condition can cause crashes, because the same ArrayList
(mPreSortedChildren or mTempArrayList in ViewGroup) is modified by two
different thread.

Test : manual

Change-Id: I9e0ad1fef4be7dc378463c06d10854e0e4c5b3d6
Fixes: 33947140
(cherry picked from commit 1b0066230edee70aa58bb866ba9b59a4a68690fc)

packages/SystemUI/src/com/android/systemui/qs/QSPanel.java

diff --git a/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java b/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java
index bdb488f..61812b6 100644
--- a/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java
+++ b/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java
@@ -345,7 +345,10 @@
 
             @Override
             public void onAnnouncementRequested(CharSequence announcement) {
-                announceForAccessibility(announcement);
+                if (announcement != null) {
+                    mHandler.obtainMessage(H.ANNOUNCE_FOR_ACCESSIBILITY, announcement)
+                            .sendToTarget();
+                }
             }
         };
         r.tile.addCallback(callback);
@@ -518,10 +521,13 @@
     private class H extends Handler {
         private static final int SHOW_DETAIL = 1;
         private static final int SET_TILE_VISIBILITY = 2;
+        private static final int ANNOUNCE_FOR_ACCESSIBILITY = 3;
         @Override
         public void handleMessage(Message msg) {
             if (msg.what == SHOW_DETAIL) {
                 handleShowDetail((Record)msg.obj, msg.arg1 != 0);
+            } else if (msg.what == ANNOUNCE_FOR_ACCESSIBILITY) {
+                announceForAccessibility((CharSequence)msg.obj);
             }
         }
     }