/**
* fh is shared by all processes.
* In case of reading, after one process finishes, and the fh moves to the new position,
* the another process use this fh to reading.
*
* int MPI_File_seek_shared(MPI_File fh, MPI_Offset offset, int whence);
* int MPI_File_get_position_shared(MPI_File fh, MPI_Offset * offset);
*
* int MPI_File_write_shared(MPI_File fh, void * buf, int count, MPI_Datatype datatype, MPI_Status * status);
* int MPI_File_read_shared(MPI_File fh, void * buf, int count, MPI_Datatype datatype, MPI_Status * status);
*
* non-blocking read/write, need MPI_Wait to wait for finishing
* int MPI_File_iread_shared(MPI_File fh, void * buf, int count, MPI_Datatype datatype, MPI_Request * request)
* int MPI_File_iwrite_shared(MPI_File fh, void * buf, int count, MPI_Datatype datatype, MPI_Request * request)
*
* read/write in oder of rankID
* int MPI_File_read_ordered(MPI_File fh, void * buf, int count, MPI_Datatype datatype, MPI_Status * status);
* int MPI_File_write_ordered(MPI_File fh, void * buf, int count, MPI_Datatype datatype, MPI_Status * status);
*/
int main(int argc, char *argv[])
{
int totalTaskNum, rankID;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rankID);
MPI_Comm_size(MPI_COMM_WORLD, &totalTaskNum);
char *filename = "file.txt";
MPI_File fh;
MPI_Status status;
MPI_File_open(MPI_COMM_WORLD, filename, MPI_MODE_CREATE | MPI_MODE_RDWR, MPI_INFO_NULL, &fh);
char write_buf[128];
sprintf(write_buf, "rankID = %d, totalTaskNum = %d\n", rankID, totalTaskNum);
// MPI_File_write_shared(fh, write_buf, strlen(write_buf), MPI_CHAR, &status);
// MPI_File_write_ordered(fh, write_buf, strlen(write_buf), MPI_CHAR, &status);
MPI_Request request;
MPI_File_iwrite_shared(fh, write_buf, strlen(write_buf), MPI_CHAR, &request);
MPI_Wait(&request, &status);
MPI_Offset offset;
MPI_File_get_position_shared(fh, &offset);
printf("1: rankID = %d, Now the position is offset = %lld\n", rankID, offset);
sleep(3);
MPI_Offset offset2 = 0;
int whence = MPI_SEEK_SET;
MPI_File_seek_shared(fh, offset2, whence);
MPI_File_get_position_shared(fh, &offset);
printf("2: rankID = %d, Now the position is offset = %lld\n", rankID, offset);
sleep(3);
char read_buf[30];
// MPI_File_read_ordered(fh, read_buf, sizeof(read_buf), MPI_CHAR, &status);
// MPI_File_read_shared(fh, read_buf, sizeof(read_buf), MPI_CHAR, &status);
MPI_File_iread_shared(fh, read_buf, sizeof(read_buf), MPI_CHAR, &request);
MPI_Wait(&request, &status);
printf("rankID = %d, content = '%s'\n", rankID, read_buf);
MPI_File_close(&fh);//after open, fh has the communicator info
MPI_Finalize();
return 0;
}
void FORTRAN_API mpi_file_get_position_shared_(MPI_Fint *fh, MPI_Offset *offset, int *ierr )
{
MPI_File fh_c;
fh_c = MPI_File_f2c(*fh);
*ierr = MPI_File_get_position_shared(fh_c, offset);
}
static int
destroyAFiledataMPINONB(void *v)
{
int iret = 0;
aFiledataM *of;
MPI_Status status;
int rankNode = commInqRankNode ();
MPI_Offset endpos;
of = (aFiledataM * ) v;
xdebug ( "IOPE%d: close file %d, name=\"%s\"",
rankNode, of->fileID, of->name );
/* close file */
xmpi(MPI_Wait(&of->request, &status));
xmpi(MPI_Barrier(commInqCommNode()));
xmpi(MPI_File_get_position_shared(of->fh, &endpos));
xmpi(MPI_File_set_size(of->fh, endpos));
iret = MPI_File_close ( & ( of->fh ));
/* file closed, cleanup */
dbuffer_cleanup ( & ( of->db1 ));
dbuffer_cleanup ( & ( of->db2 ));
free ( of );
xdebug ( "IOPE%d: closed file, cleaned up, return",
rankNode );
return iret == MPI_SUCCESS ? 0 : -1;
}
JNIEXPORT jlong JNICALL Java_mpi_File_getPositionShared(
JNIEnv *env, jobject jthis, jlong fh)
{
MPI_Offset offset;
int rc = MPI_File_get_position_shared((MPI_File)fh, &offset);
ompi_java_exceptionCheck(env, rc);
return (jlong)offset;
}
void ompi_file_get_position_shared_f(MPI_Fint *fh, MPI_Offset *offset,
MPI_Fint *ierr)
{
int c_ierr;
MPI_File c_fh = MPI_File_f2c(*fh);
MPI_Offset c_offset;
c_ierr = MPI_File_get_position_shared(c_fh, &c_offset);
if (NULL != ierr) *ierr = OMPI_INT_2_FINT(c_ierr);
if (MPI_SUCCESS == c_ierr) {
*offset = (MPI_Offset) c_offset;
}
}
