/*@
MPI_Buffer_detach - Removes an existing buffer (for use in MPI_Bsend etc)
Output Parameters:
+ buffer - initial buffer address (choice)
- size - buffer size, in bytes (integer)
Notes:
The reason that 'MPI_Buffer_detach' returns the address and size of the
buffer being detached is to allow nested libraries to replace and restore
the buffer. For example, consider
.vb
int size, mysize, idummy;
void *ptr, *myptr, *dummy;
MPI_Buffer_detach( &ptr, &size );
MPI_Buffer_attach( myptr, mysize );
...
... library code ...
...
MPI_Buffer_detach( &dummy, &idummy );
MPI_Buffer_attach( ptr, size );
.ve
This is much like the action of the Unix signal routine and has the same
strengths (it is simple) and weaknesses (it only works for nested usages).
Note that for this approach to work, MPI_Buffer_detach must return MPI_SUCCESS
even when there is no buffer to detach. In that case, it returns a size of
zero. The MPI 1.1 standard for 'MPI_BUFFER_DETACH' contains the text
.vb
The statements made in this section describe the behavior of MPI for
buffered-mode sends. When no buffer is currently associated, MPI behaves
as if a zero-sized buffer is associated with the process.
.ve
This could be read as applying only to the various Bsend routines. This
implementation takes the position that this applies to 'MPI_BUFFER_DETACH'
as well.
.N fortran
The Fortran binding for this routine is different. Because Fortran
does not have pointers, it is impossible to provide a way to use the
output of this routine to exchange buffers. In this case, only the
size field is set.
Notes for C:
Even though the 'bufferptr' argument is declared as 'void *', it is
really the address of a void pointer. See the rationale in the
standard for more details.
@*/
int MPI_Buffer_detach(
void *bufferptr,
int *size )
{
disableSignal();
return MPIR_BsendRelease( (void **)bufferptr, size );
revertSignal();
}
/*@
MPI_Buffer_detach - Removes an existing buffer (for use in MPI_Bsend etc)
Output Parameters:
+ buffer - initial buffer address (choice)
- size - buffer size, in bytes (integer)
Notes:
The reason that 'MPI_Buffer_detach' returns the address and size of the
buffer being detached is to allow nested libraries to replace and restore
the buffer. For example, consider
.vb
int size, mysize, idummy;
void *ptr, *myptr, *dummy;
MPI_Buffer_detach( &ptr, &size );
MPI_Buffer_attach( myptr, mysize );
...
... library code ...
...
MPI_Buffer_detach( &dummy, &idummy );
MPI_Buffer_attach( ptr, size );
.ve
This is much like the action of the Unix signal routine and has the same
strengths (it is simple) and weaknesses (it only works for nested usages).
Note that for this approach to work, MPI_Buffer_detach must return MPI_SUCCESS
even when there is no buffer to detach. In that case, it returns a size of
zero. The MPI 1.1 standard for 'MPI_BUFFER_DETACH' contains the text
.vb
The statements made in this section describe the behavior of MPI for
buffered-mode sends. When no buffer is currently associated, MPI behaves
as if a zero-sized buffer is associated with the process.
.ve
This could be read as applying only to the various Bsend routines. This
implementation takes the position that this applies to 'MPI_BUFFER_DETACH'
as well.
.N fortran
The Fortran binding for this routine is different. Because Fortran
does not have pointers, it is impossible to provide a way to use the
output of this routine to exchange buffers. In this case, only the
size field is set.
Notes for C:
Even though the 'bufferptr' argument is declared as 'void *', it is
really the address of a void pointer. See the rationale in the
standard for more details.
@*/
EXPORT_MPI_API int MPI_Buffer_detach(
void *bufferptr,
int *size )
{
return MPIR_BsendRelease( (void **)bufferptr, size );
}