[petsc-dev] Integrating PFLOTRAN, PETSC & SAMRAI

[Boyce Griffith]

On 6/6/11 5:06 PM, Boyce Griffith wrote:
>
>
> On 6/6/11 4:59 PM, Jed Brown wrote:
>> On Mon, Jun 6, 2011 at 22:49, Boyce Griffith <griffith at cims.nyu.edu
>> <mailto:griffith at cims.nyu.edu>> wrote:
>>
>> I stash a pointer to the SAMRAI vector object in the PETSc Vec as
>> vec->data.
>>
>>
>> Great, somewhere in your FormResidual(), you access this data. Otherwise
>> there would be no way for you to change the output data (unless you did
>> some sort of hidden sharing which would be super fragile). So why not
>> have that API increment the state? For example, VecRestoreArray()
>> increments state for PETSc vectors. Since everyone accesses the vector
>> through this API, they never have to call PetscObjectStateIncrease()
>> themselves.
>
> I never call VecGetArray() / VecRestoreArray() --- it doesn't really
> make sense here because there is no single array associated with the
> data. In fact, the wrapper class sets ops->getarray to PETSC_NULL.
>
>> Why not have your accessor manage the state? This would be the logically
>> consistent way to do it.
>
> I agree --- right now, I have a getVector() method but no
> restoreVector() method. Probably the right thing to do is to have a
> restoreVector() function that updates the state.

Oh, right, except that getVector() is called even on Vec's that are not 
modified.

-- Boyce