<AWT Dev> RFR: 8170493: JNI exception pending in JavaComponentAccessibility.m:142

[Sergey Bylokhov]

Hi, Phil.
Nothing from my side.

> 
> Any [additonial] comment on this ?
> 
> -phil.
> 
> On 01/26/2017 01:55 PM, Philip Race wrote:
>> LIke I said in the bug report, if we get OOME here then we'll get more
>> from the following calls and if we want to make this accessibility code robust
>> against this theoretical problem a massive destabilising re-write is needed.
>> 
>> How about this change instead
>> --- a/src/java.desktop/macosx/native/libawt_lwawt/awt/JavaComponentAccessibility.m
>> +++ b/src/java.desktop/macosx/native/libawt_lwawt/awt/JavaComponentAccessibility.m
>> @@ -136,7 +136,7 @@
>>         fJavaRole = [javaRole retain];
>> 
>>         fAccessible = (*env)->NewWeakGlobalRef(env, accessible);
>> -
>> +        (*env)->ExceptionClear(env); // in case of OOME
>>         jobject jcomponent = [(AWTView *)fView awtComponent:env];
>>         fComponent = (*env)->NewWeakGlobalRef(env, jcomponent);
>>         (*env)->DeleteLocalRef(env, jcomponent);
>> 
>> -----
>> 
>> ExceptionClear is harmless if there is no exception pending.
>> And we will be "using jni correctly" in making the next call to NewWeakGlobalRef
>> .. .even if it fails.
>> 
>> fAccessible is mostly guarded against use of NULL so it might even make things better
>> but definitely won't harm anything.
>> 
>> If we ever see a real issue here that de-stabilising re-write will be needed.
>> But not in JDK 9.
>> 
>> Its either make the mostly useless small change or "will not fix" but
>> we are supposed to be fixing these JNI correctness bugs.
>> 
>> -phil.
>> 
>> On 1/16/17, 7:17 AM, Sergey Bylokhov wrote:
>>> Hi, Phi.
>>>> // these constants are duplicated in CAccessibility.java
>>>> @@ -136,7 +137,7 @@
>>>>         fJavaRole = [javaRole retain];
>>>> 
>>> I am not sure but it seems strange that we will return the "self"(and will use it later), because it is not nil and was not properly initialized (for example fActionsLOCK field which is used for synchronization will be nil).
>