[7u10] Review request for 7188708 - REGRESSION: closed/java/awt/EventQueue/PostEventOrderingTest.java fails

[Oleg Pekhovskiy]

Hi David,

I thought about that variant first, then something stopped me.
Anyway, it resolves the regression.

Please review the changes here:
http://cr.openjdk.java.net/~bagiras/7u10/7188708.2/

Thanks,
Oleg

9/7/2012 3:36 PM, David Holmes wrote:
> Hi Oleg,
>
> It seems to me that the original code has the
>
>  isFlushingPendingEvents = false;
>
> in the wrong place: it should only ever be cleared by an invocation 
> that set it. So a simple reorganization of the code would achieve that:
>
>  553     public static void flushPendingEvents()  {
>  554         flushLock.lock();
>  555         try {
>  556             // Don't call flushPendingEvents() recursively
>  557             if (!isFlushingPendingEvents) {
>  558                 isFlushingPendingEvents = true;
> +                     try {
>     559                 AppContext appContext = 
> AppContext.getAppContext();
>     560                 PostEventQueue postEventQueue =
>     561 (PostEventQueue)appContext.get(POST_EVENT_QUEUE_KEY);
>     562                 if (postEventQueue != null) {
>     563                     postEventQueue.flush();
>     564                 }
> +                    } finally {
> +                       isFlushingPendingEvents = false;
> +                    }
>  565             }
>  566         } finally {
> -567
>  568             flushLock.unlock();
>  569         }
>  570     }
>
> David
> -----
>
> On 7/09/2012 11:57 AM, Oleg Pekhovskiy wrote:
>> Hi!
>>
>> Please review the fix for CR:
>> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7188708
>>
>> Webrev:
>> http://cr.openjdk.java.net/~bagiras/7u10/7188708.1/
>>
>> The reason is that isFlushingPendingEvents in
>> SunToolkit.flushPendingEvents() is reset
>> after the first recursive call of flushPendingEvents(). Thus, if there
>> are several pending events in PostEventQueue,
>> recursion would be rejected only for the first event, allowing nested
>> call of PostEventQueue.flush() after.
>>
>> To resolve the problem I added the counter "flushNestingLevel" instead
>> of the flag "isFlushingPendingEvents".
>> It's increased each time entering SunToolkit.flushPendingEvents() and
>> decreased on exit.
>> So, PostEventQueue.flush() method is called only when we enter
>> SunToolkit.flushPendingEvents() for the first time
>> within one thread.
>>
>> That fix was prepared ONLY for 7u10.
>> For JDK 8 the fix for "CR7186109 - Simplify lock machinery for
>> PostEventQueue & EventQueue" should cover this case.
>>
>> Thanks,
>> Oleg