[petsc-dev] MatISGetLocalMat: need to MatDestroy the returned local matrice ?

[Jed Brown]

It should get/restore.

On May 19, 2017 12:10:32 PM MDT, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>   Jed,
>
>     Should this utilize the Get/Restore paradigm? 
>
>If not should the name be different to prevent confusion? Currently we
>have 
>
>  XXXCreate -->  user needs to call a destroy
>
>   XXXXGetYYY  --> user needs to call a restore (but not always?)
>
>   Could we introduce say
>
>    XXXAccessYYY   --> user does not call destroy or restore ?
>
>  Barry
>
>> On May 19, 2017, at 9:20 AM, Jed Brown <jed at jedbrown.org> wrote:
>> 
>> Thanks.  I just pushed this.
>> 
>> commit 96a6f12955a790d77f6eb7eb6b1dcf9dd5e1cf30
>> Author: Jed Brown <jed at jedbrown.org>
>> Date:   Fri May 19 08:17:45 2017 -0600
>> 
>>    MatISGetLocalMat: add note on reference counting
>> 
>>    Reported-by: Franck Houssen <franck.houssen at inria.fr>
>> 
>> diff --git a/src/mat/impls/is/matis.c b/src/mat/impls/is/matis.c
>> index dc4a894aae..287c0aa554 100644
>> --- a/src/mat/impls/is/matis.c
>> +++ b/src/mat/impls/is/matis.c
>> @@ -837,6 +837,9 @@ PetscErrorCode MatISGetLocalMat_IS(Mat mat,Mat
>*local)
>>   matrix and want to provide it to the inner matrix object to improve
>the performance
>>   of the MatSetValues() operation.
>> 
>> +  This function does not increase the reference count for the local
>Mat.  Do not destroy it and do not attempt to use
>> +  your reference after destroying the parent mat.
>> +
>> .seealso: MATIS
>> @*/
>> PetscErrorCode MatISGetLocalMat(Mat mat,Mat *local)
>> 
>> Franck Houssen <franck.houssen at inria.fr> writes:
>> 
>>> Hello, 
>>> 
>>> Do I need to MatDestroy the local matrix returned by
>MatISGetLocalMat ? (the global matrix has been created with
>MatCreateIS) 
>>> 
>>> Tried to look in the source tree... But I'am not sure to get the
>answer: in petsc-3.7.6/src/mat/impls/is/matis.c, MatISGetLocalMat seems
>to call MatISGetLocalMat_C, but, I can't find MatISGetLocalMat_C in the
>source tree !?... 
>>> 
>>> Franck 
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