/*@
MPI_File_read_ordered_begin - Begin a split collective read using shared file pointer
Input Parameters:
. fh - file handle (handle)
. count - number of elements in buffer (nonnegative integer)
. datatype - datatype of each buffer element (handle)
Output Parameters:
. buf - initial address of buffer (choice)
.N fortran
@*/
int MPI_File_read_ordered_begin(MPI_File fh, void *buf, int count,
MPI_Datatype datatype)
{
int error_code, nprocs, myrank;
MPI_Count datatype_size;
int source, dest;
ADIO_Offset shared_fp, incr;
ADIO_File adio_fh;
static char myname[] = "MPI_FILE_READ_ORDERED_BEGIN";
void *xbuf=NULL, *e32_buf=NULL;
MPIU_THREAD_CS_ENTER(ALLFUNC,);
adio_fh = MPIO_File_resolve(fh);
/* --BEGIN ERROR HANDLING-- */
MPIO_CHECK_FILE_HANDLE(adio_fh, myname, error_code);
MPIO_CHECK_COUNT(adio_fh, count, myname, error_code);
MPIO_CHECK_DATATYPE(adio_fh, datatype, myname, error_code);
if (adio_fh->split_coll_count)
{
error_code = MPIO_Err_create_code(MPI_SUCCESS, MPIR_ERR_RECOVERABLE,
myname, __LINE__, MPI_ERR_IO,
"**iosplitcoll", 0);
error_code = MPIO_Err_return_file(adio_fh, error_code);
goto fn_exit;
}
/* --END ERROR HANDLING-- */
adio_fh->split_coll_count = 1;
MPI_Type_size_x(datatype, &datatype_size);
/* --BEGIN ERROR HANDLING-- */
MPIO_CHECK_INTEGRAL_ETYPE(adio_fh, count, datatype_size, myname, error_code);
MPIO_CHECK_FS_SUPPORTS_SHARED(adio_fh, myname, error_code);
MPIO_CHECK_COUNT_SIZE(adio_fh, count, datatype_size, myname, error_code);
/* --END ERROR HANDLING-- */
ADIOI_TEST_DEFERRED(adio_fh, myname, &error_code);
MPI_Comm_size(adio_fh->comm, &nprocs);
MPI_Comm_rank(adio_fh->comm, &myrank);
incr = (count*datatype_size)/adio_fh->etype_size;
/* Use a message as a 'token' to order the operations */
source = myrank - 1;
dest = myrank + 1;
if (source < 0) source = MPI_PROC_NULL;
if (dest >= nprocs) dest = MPI_PROC_NULL;
MPI_Recv(NULL, 0, MPI_BYTE, source, 0, adio_fh->comm, MPI_STATUS_IGNORE);
ADIO_Get_shared_fp(adio_fh, incr, &shared_fp, &error_code);
/* --BEGIN ERROR HANDLING-- */
if (error_code != MPI_SUCCESS)
{
error_code = MPIO_Err_return_file(adio_fh, error_code);
goto fn_exit;
}
/* --END ERROR HANDLING-- */
MPI_Send(NULL, 0, MPI_BYTE, dest, 0, adio_fh->comm);
xbuf = buf;
if (adio_fh->is_external32)
{
MPI_Aint e32_size = 0;
error_code = MPIU_datatype_full_size(datatype, &e32_size);
if (error_code != MPI_SUCCESS)
goto fn_exit;
e32_buf = ADIOI_Malloc(e32_size*count);
xbuf = e32_buf;
}
ADIO_ReadStridedColl(adio_fh, xbuf, count, datatype, ADIO_EXPLICIT_OFFSET,
shared_fp, &adio_fh->split_status, &error_code);
/* --BEGIN ERROR HANDLING-- */
if (error_code != MPI_SUCCESS)
error_code = MPIO_Err_return_file(adio_fh, error_code);
/* --END ERROR HANDLING-- */
if (e32_buf != NULL) {
error_code = MPIU_read_external32_conversion_fn(xbuf, datatype,
count, e32_buf);
ADIOI_Free(e32_buf);
}
fn_exit:
MPIU_THREAD_CS_EXIT(ALLFUNC,);
return error_code;
}