[petsc-dev] Fortran callbacks when null

[Jed Brown]

This looks fine to me.

Barry Smith <bsmith at mcs.anl.gov> writes:

>   Jed,
>
>      It seems currently for any optional callbacks from Fortran we have this ugly code
>
>   if (FORTRANNULLFUNCTION(d)) {
>       *ierr = TSMonitorSet(*ts,ourmonitor,NULL,NULL);
>     } else {
>       *ierr = PetscObjectSetFortranCallback((PetscObject)*ts,PETSC_FORTRAN_CALLBACK_CLASS,&_cb.mondestroy,(PetscVoidFunction)d,mctx);
>       *ierr = TSMonitorSet(*ts,ourmonitor,NULL,ourmonitordestroy);
>     }
>
> This posses multiply uglinesses 
>
> 1) the same duplicate  if () ugliness people need to write and maintain for each XXXSetFunctionXXX() routine in PETSc
>
> 2) If the user passes in, by mistake something like PETSC_NULL_SOMETHING else as the function we cannot error check for that since FORTRANNULLFUNCTION is inside an if ()
>
> Could we refactor these so that 
>
> a) PetscObjectSetFortranCallback() handles a NULL function (by simply not calling the function in that case) and
>
> b) we replace the if (FORTRANNULLFUNCTION) block monstrosity by something like 
>
>   CHKFORTRANNULLFUNCTION(d);  <<< this does error checking
>   *ierr = PetscObjectSetFortranCallback((PetscObject)*ts,PETSC_FORTRAN_CALLBACK_CLASS,&_cb.mondestroy,(PetscVoidFunction)d,mctx); if (*ierr) return;
>   *ierr = TSMonitorSet(*ts,ourmonitor,NULL,ourmonitordestroy);
>
>    everywhere?
>
>    If this looks correct to you, just let me know and I'll implement it.
>
>   Barry
>
>
>
>
>> Begin forwarded message:
>> 
>> From: Praveen C <cpraveen at gmail.com>
>> Subject: Re: [petsc-users] Segmentation fault due to TSDestroy
>> Date: March 20, 2017 at 7:46:18 AM CDT
>> To: petsc-users <petsc-users at mcs.anl.gov>
>> 
>> It turns out the problem was with this
>> 
>>    call TSMonitorSet(ts, Monitor, ctx, PETSC_NULL_OBJECT, ierr); CHKERRQ(ierr)
>> 
>> The correct way is
>> 
>>    call TSMonitorSet(ts, Monitor, ctx, PETSC_NULL_FUNCTION, ierr); CHKERRQ(ierr)
>> 
>> Thanks
>> praveen
>> 
>> On Sat, Mar 18, 2017 at 9:30 PM, Satish Balay <balay at mcs.anl.gov <mailto:balay at mcs.anl.gov>> wrote:
>> Perhaps there is some memory corruption - you can try runnng the code with valgrind.
>> 
>> Satish
>> 
>> On Sat, 18 Mar 2017, Praveen C wrote:
>> 
>> > Dear all
>> >
>> > I get a segmentation fault when I call TSDestroy. Without TSDestroy the
>> > code runs fine. I have included portion of my code below.
>> >
>> > subroutine runts(ctx)
>> >    use userdata
>> >    use comdata
>> >    use mtsdata
>> >    implicit none
>> > #include <petsc/finclude/petsc.h90>
>> >    type(tsdata) :: ctx
>> >    ! Local variables
>> >    integer,parameter :: h = 100 ! File id for history file
>> >    TS                :: ts
>> >    Vec               :: u
>> >    PetscErrorCode    :: ierr
>> >    external          :: RHSFunction, Monitor
>> >
>> >    call VecDuplicate(ctx%p%v_res, u, ierr); CHKERRQ(ierr)
>> >
>> >    ! Copy initial condition into u
>> >    call VecCopy(ctx%p%v_u, u, ierr); CHKERRQ(ierr)
>> >
>> >    call TSCreate(PETSC_COMM_WORLD, ts, ierr); CHKERRQ(ierr)
>> >    call TSSetProblemType(ts, TS_NONLINEAR, ierr); CHKERRQ(ierr)
>> >    call TSSetRHSFunction(ts, PETSC_NULL_OBJECT, RHSFunction, ctx, ierr);
>> > CHKERRQ(ierr)
>> >    call TSSetInitialTimeStep(ts, 0.0, dtg, ierr); CHKERRQ(ierr)
>> >    call TSSetType(ts, TSRK, ierr); CHKERRQ(ierr);
>> >    call TSSetDuration(ts, itmax, tfinal, ierr); CHKERRQ(ierr);
>> >    call TSSetExactFinalTime(ts, TS_EXACTFINALTIME_MATCHSTEP, ierr);
>> > CHKERRQ(ierr);
>> >    call TSMonitorSet(ts, Monitor, ctx, PETSC_NULL_OBJECT, ierr);
>> > CHKERRQ(ierr)
>> >    call TSSetSolution(ts, u, ierr); CHKERRQ(ierr)
>> >    call TSSetFromOptions(ts, ierr); CHKERRQ(ierr)
>> >    call TSSetUp(ts, ierr); CHKERRQ(ierr)
>> >
>> >    call TSSolve(ts, u, ierr); CHKERRQ(ierr)
>> >
>> >    call VecCopy(u, ctx%p%v_u, ierr); CHKERRQ(ierr)
>> >    call VecDestroy(u, ierr); CHKERRQ(ierr)
>> >    call TSDestroy(ts, ierr); CHKERRQ(ierr)
>> >
>> > end subroutine runts
>> >
>> > Thanks
>> > praveen
>> >
>> 
>> 
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