ad_pfs_read.c

mpi并行计算的c++代码 可用vc或gcc编译通过 可以用来搭建并行计算试验环境

/* -*- Mode: C; c-basic-offset:4 ; -*- */
/* 
 *
 *   Copyright (C) 1997 University of Chicago. 
 *   See COPYRIGHT notice in top-level directory.
 */

#include "ad_pfs.h"
#ifdef PROFILE
#include "mpe.h"
#endif

void ADIOI_PFS_ReadContig(ADIO_File fd, void *buf, int count, 
                     MPI_Datatype datatype, int file_ptr_type,
		     ADIO_Offset offset, ADIO_Status *status, int *error_code)
{
    int err=-1, datatype_size, len;
    static char myname[] = "ADIOI_PFS_READCONTIG";

    MPI_Type_size(datatype, &datatype_size);
    len = datatype_size * count;

    if (file_ptr_type == ADIO_EXPLICIT_OFFSET) {
        if (fd->fp_sys_posn != offset) {
#ifdef PROFILE
	    MPE_Log_event(11, 0, "start seek");
#endif
	    lseek(fd->fd_sys, offset, SEEK_SET);
#ifdef PROFILE
	    MPE_Log_event(12, 0, "end seek");
#endif
	}
#ifdef PROFILE
	MPE_Log_event(3, 0, "start read");
#endif
	err = _cread(fd->fd_sys, buf, len);
#ifdef PROFILE
	MPE_Log_event(4, 0, "end read");
#endif
        fd->fp_sys_posn = offset + err;
	/* individual file pointer not updated */        
    }
    else {  /* read from curr. location of ind. file pointer */
        if (fd->fp_sys_posn != fd->fp_ind) {
#ifdef PROFILE
	    MPE_Log_event(11, 0, "start seek");
#endif
	    lseek(fd->fd_sys, fd->fp_ind, SEEK_SET);
#ifdef PROFILE
	    MPE_Log_event(12, 0, "end seek");
#endif
	}
#ifdef PROFILE
	MPE_Log_event(3, 0, "start read");
#endif
	err = _cread(fd->fd_sys, buf, len);
#ifdef PROFILE
	MPE_Log_event(4, 0, "end read");
#endif
	fd->fp_ind += err; 
        fd->fp_sys_posn = fd->fp_ind;
    }         

#ifdef HAVE_STATUS_SET_BYTES
    if (err != -1) MPIR_Status_set_bytes(status, datatype, err);
#endif

    if (err == -1) {
	*error_code = MPIO_Err_create_code(MPI_SUCCESS, MPIR_ERR_RECOVERABLE,
					   myname, __LINE__, MPI_ERR_IO,
					   "**io",
					   "**io %s", strerror(errno));
    }
    else *error_code = MPI_SUCCESS;
}