[petsc-dev] MatAXPY does not increase state

[Jed Brown]

"Jose E. Roman" <jroman at dsic.upv.es> writes:

> Hi.
>
> We are having problems since the MatStructure flag was removed from KSPSetOperators.
> https://bitbucket.org/petsc/petsc/commits/b37f9b8
>
> Tracking our problem leads to blame MatAXPY, which does not increase
> the state of the first Mat argument. The attached patch fixes the
> problem for us. Is this the right thing to do?

Sort of.

> diff --git a/src/mat/impls/aij/seq/aij.c b/src/mat/impls/aij/seq/aij.c
> index f05b858..91a51d5 100644
> --- a/src/mat/impls/aij/seq/aij.c
> +++ b/src/mat/impls/aij/seq/aij.c
> @@ -2862,6 +2862,7 @@ PetscErrorCode MatAXPY_SeqAIJ(Mat Y,PetscScalar a,Mat X,MatStructure str)
>      ierr = MatHeaderReplace(Y,B);CHKERRQ(ierr);
>      ierr = PetscFree(nnz);CHKERRQ(ierr);
>    }
> +  ierr = PetscObjectStateIncrease((PetscObject)Y);CHKERRQ(ierr);
>    PetscFunctionReturn(0);
>  }

I would rather move this up to the place where memory is actually
accessed.  Vec typically uses VecGetArray to manage access (and state),
while Mat usually uses direct access.  There may be many places with
this issue.

> diff --git a/src/mat/utils/gcreate.c b/src/mat/utils/gcreate.c
> index 55665bf..eb8fd76 100644
> --- a/src/mat/utils/gcreate.c
> +++ b/src/mat/utils/gcreate.c
> @@ -336,8 +336,9 @@ PetscErrorCode MatHeaderMerge(Mat A,Mat C)
>  #define __FUNCT__ "MatHeaderReplace"
>  PETSC_EXTERN PetscErrorCode MatHeaderReplace(Mat A,Mat C)
>  {
> -  PetscErrorCode ierr;
> -  PetscInt       refct;
> +  PetscErrorCode   ierr;
> +  PetscInt         refct;
> +  PetscObjectState state;
>  
>    PetscFunctionBegin;
>    PetscValidHeaderSpecific(A,MAT_CLASSID,1);
> @@ -356,9 +357,11 @@ PETSC_EXTERN PetscErrorCode MatHeaderReplace(Mat A,Mat C)
>  
>    /* copy C over to A */
>    refct = ((PetscObject)A)->refct;
> +  state = ((PetscObject)A)->state;
>    ierr  = PetscMemcpy(A,C,sizeof(struct _p_Mat));CHKERRQ(ierr);
>  
>    ((PetscObject)A)->refct = refct;
> +  ((PetscObject)A)->state = state;

Surely this should increment state so that someone holding a reference
to A can tell that it has changed.

>    ierr = PetscFree(C);CHKERRQ(ierr);
>    PetscFunctionReturn(0);
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