<AWT Dev> Review request for 8165829: Android Studio 2.x crashes with NPE at sun.lwawt.macosx.CAccessibility.getAccessibleIndexInParent

[Anton Tarasov]

On 9/16/2016 1:32 PM, Sergey Bylokhov wrote:
> On 15.09.16 14:48, Anton Tarasov wrote:
>>> Yes, and my suggestion was to use the new method and default values
>>> everywhere instead of invokeAndWait(Callable,Component).
>>
>> But the default value for a reference would be null, there's no need to
>> request something else, unlike for primitive wrappers.
>>
>> Or your idea is to force passing a def value anyway?
>
> If the references like Point from getLocationOnScreen() can be null, 
> then ok. looks fine.

Yes, it can.

Anton.

>
>>
>> Anton.
>>
>>>>> On 15.09.16 12:45, Anton Tarasov wrote:
>>>>>> Hello,
>>>>>>
>>>>>> Please review the fix:
>>>>>>
>>>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8165829
>>>>>> webrev: http://cr.openjdk.java.net/~ant/JDK-8165829/jdk9/webrev.0
>>>>>>
>>>>>> (The bug is currently closed as “not an issue”, which is not quite
>>>>>> true.
>>>>>> So once and if the fix is approved I can take the ownership of the
>>>>>> bug).
>>>>>>
>>>>>> The problem is this. Sometimes when a frame is closed there may
>>>>>> appear a
>>>>>> race condition:
>>>>>>
>>>>>> - removeNotify() is called on the frame on EDT and it removes all 
>>>>>> the
>>>>>> events associated with the frame from the event queue.
>>>>>>
>>>>>> - The frame is requested by accessibility via the CAccessibility
>>>>>> static
>>>>>> methods (like CAccessibility.getAccessibleIndexInParent). Those
>>>>>> methods
>>>>>> are called from native on AppKit thread and they perform via
>>>>>> invokeAndWait. The latter is wrapped with an InvocationEvent whose
>>>>>> source is set to the frame. But, once the event is put on the event
>>>>>> queue, it's purged by the removeNotify() call. As the result,
>>>>>> invokeAndWait returns null. Then, in some of the mentioned methods
>>>>>> 'null' is unboxed to a primitive 'int' or 'boolean' which results
>>>>>> in NPE
>>>>>> propagated to native. On the native side, the NPE is not properly
>>>>>> handled and is just re-thrown.
>>>>>>
>>>>>> I don't have a simple and safe solution for the race. So, I 
>>>>>> suggest to
>>>>>> fix the NPE/crash at least.
>>>>>>
>>>>>> Thanks,
>>>>>> Anton.
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
>