706657 - java.lang.NullPointerException @ TabsTray$TabsAdapter$2.onClick(TabsTray.java:246)

Status: RESOLVED WORKSFORME

(Firefox for Android Graveyard :: General, defect, P3)

Description

[Aaron Train [:aaronmt]]

I/ActivityManager(  110): Displayed org.mozilla.fennec/org.mozilla.gecko.TabsTray: +324ms
I/dalvikvm( 2916): Total arena pages for JIT: 11
I/GeckoApp( 2724): Got message: Tab:Selected
I/GeckoApp( 2724): Switched to tab: 7
D/dalvikvm( 2724): GC_EXTERNAL_ALLOC freed 334K, 55% free 3526K/7815K, external 13443K/15017K, paused 51ms
I/GeckoDoorHangerPopup( 2724): Showing all doorhangers for tab: 7
I/GeckoApp( 2724): Got message: Tab:Closed
I/GeckoApp( 2724): Destroyed a tab
I/GeckoTabs( 2724): Removed a tab with id: 8
I/GeckoDoorHangerPopup( 2724): Showing all doorhangers for tab: 7
E/GeckoApp( 2724): top level exception
E/GeckoApp( 2724): java.lang.NullPointerException
E/GeckoApp( 2724): 	at org.mozilla.gecko.TabsTray$TabsAdapter$2.onClick(TabsTray.java:246)
E/GeckoApp( 2724): 	at android.view.View.performClick(View.java:2485)
E/GeckoApp( 2724): 	at android.view.View$PerformClick.run(View.java:9080)
E/GeckoApp( 2724): 	at android.os.Handler.handleCallback(Handler.java:587)
E/GeckoApp( 2724): 	at android.os.Handler.dispatchMessage(Handler.java:92)
E/GeckoApp( 2724): 	at android.os.Looper.loop(Looper.java:130)
E/GeckoApp( 2724): 	at org.mozilla.gecko.GeckoApp$24.run(GeckoApp.java:1333)
E/GeckoApp( 2724): 	at android.os.Handler.handleCallback(Handler.java:587)
E/GeckoApp( 2724): 	at android.os.Handler.dispatchMessage(Handler.java:92)
E/GeckoApp( 2724): 	at android.os.Looper.loop(Looper.java:130)
E/GeckoApp( 2724): 	at android.app.ActivityThread.main(ActivityThread.java:3683)
E/GeckoApp( 2724): 	at java.lang.reflect.Method.invokeNative(Native Method)
E/GeckoApp( 2724): 	at java.lang.reflect.Method.invoke(Method.java:507)
E/GeckoApp( 2724): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
E/GeckoApp( 2724): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
E/GeckoApp( 2724): 	at dalvik.system.NativeStart.main(Native Method)

This happened at some point in closing a tab; don't have all the STR.

--
Samsung Nexus S (Android 2.3.6)
20111130112926
http://hg.mozilla.org/projects/birch/rev/f605f17ba73d

Comment 1

[Sriram Ramasubramanian [:sriram]]

Attachment: Patch

This patch adds a preventive check while accessing tabs.

Comment 2

[Mark Finkle (:mfinkle) (use needinfo?)]

Comment on attachment 578117 [details] [diff] [review]
Patch

>                         Tab tab = tabs.getTab(tabId);
> 
>                         if (tabs.isSelectedTab(tab)) {
>                             int index = tabs.getIndexOf(tab);
>                             if (index >= 1)
>                                 index--;
>                             else
>                                 index = 1;
>-                            int id = tabs.getTabAt(index).getId();
>-                            GeckoAppShell.sendEventToGecko(new GeckoEvent("Tab:Select", String.valueOf(id)));
>+
>+                            Tab nextTab = tabs.getTabAt(index);
>+                            if (nextTab != null) {
>+                                int id = nextTab.getId();
>+                                GeckoAppShell.sendEventToGecko(new GeckoEvent("Tab:Select", String.valueOf(id)));
>+                            }
>+                            
>                             GeckoAppShell.sendEventToGecko(new GeckoEvent("Tab:Close", v.getTag().toString()));
>                         } else {

Just trying to figure this out a bit:
* If the tab we are closing is the selected tab, we check the current tab index
  * if greater than or equal to 1, select the next lower tab in the list
  * if equal to 0 use the tab at index 1 (technically the index could be -1 but the tab must exist since we just checked if it was selected.

The tab at the nextTab index might not exist! How can that be? We must be missing a race condition here somewhere.

* I don't like separating the Tab:Select and Tab:Close. That might lead to a situation where there is not tab selected in browser.js

Can we add more logging to see what the cause of the race could be?

Comment 3

[Lucas Rocha (:lucasr)]

Bug 701884 is probably related.

Comment 4

[Mark Finkle (:mfinkle) (use needinfo?)]

Aaron - Can you still repro this?