[liblouis-liblouisxml] Re: Java bindings for lou_registerLogCallback and lou_setLogLevel
- From: Bert Frees <bertfrees@xxxxxxxxx>
- To: liblouis-liblouisxml@xxxxxxxxxxxxx
- Date: Thu, 12 Jun 2014 16:44:17 +0200
From my experience, it will not lead to a crash, the logging will just
silently fail. The program will just continue as if nothing happened
except that nothing will be logged. The developer may not understand why
if this behaviour is not documented. So I'm considering to add this
wrapper function.
Bert
Michael Whapples writes:
> Hello,
> I think my concern mostly relates to the possible result the user will
> experience.
>
> Could the callback object being garbage collected lead to a crash of the
> JVM? If yes then that is probably not acceptable in my mind.
>
> It it could only lead to a exception being thrown then its not quite so
> bad and may be let the application developer choose.
>
> Michael Whapples
> On 12/06/2014 14:13, Bert Frees wrote:
>> Hi Michael,
>>
>> Good point.
>>
>> No, JNA doesn't take care of that and neither do my bindings. It's
>> currently the responsibility of the calling application to keep a
>> reference to the callback object.
>>
>> I guess I could make a convenience wrapper function that keeps a
>> reference for you, just like you do in the liblouisutdml
>> bindings. Something to be considered.
>>
>> Thanks,
>> Bert
>>
>>
>>
>> Michael Whapples writes:
>>
>>> Thanks for sharing that.
>>>
>>> One thing I think I notice in that is that your bindings never take a
>>> reference to the callback object. This is not a problem providing the
>>> calling application uses it correctly, but should it not then
>>> potentially the callback object could be garbage collected and then
>>> liblouis may try and call it and things fall over. Is that correct or
>>> does JNA do something?
>>>
>>> In the LibLouisUTDML bindings I get the bindings to take and hold a
>>> global reference to the callback object and only release that reference
>>> when lou_registerLogCallback is called again (may it be called with NULL
>>> to free the callback or another callback object).
>>>
>>> Michael Whapples
>>> On 12/06/2014 12:38, Bert Frees wrote:
>>>> Hello Michael,
>>>>
>>>> I've updated my JNA based Java bindings to support
>>>> lou_registerLogCallback and lou_setLogLevel. See
>>>> https://github.com/liblouis/liblouis-java/commit/a30a1ad7212bed369c3ffd651c393ca241f83ae6
>>>> if you like to know how I did it.
>>>>
>>>> Cheers,
>>>> Bert
>>>> For a description of the software, to download it and links to
>>>> project pages go to http://www.abilitiessoft.com
>>> For a description of the software, to download it and links to
>>> project pages go to http://www.abilitiessoft.com
>> For a description of the software, to download it and links to
>> project pages go to http://www.abilitiessoft.com
>
> For a description of the software, to download it and links to
> project pages go to http://www.abilitiessoft.com
For a description of the software, to download it and links to
project pages go to http://www.abilitiessoft.com
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