openmpi/ompi/mca/sharedfp/sm/sharedfp_sm_read.c

/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2005 The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  All rights
 *                         reserved.
 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * Copyright (c) 2013      University of Houston. All rights reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 */


#include "ompi_config.h"
#include "sharedfp_sm.h"

#include "mpi.h"
#include "ompi/constants.h"
#include "ompi/mca/sharedfp/sharedfp.h"

int mca_sharedfp_sm_read ( mca_io_ompio_file_t *fh,
                           void *buf, int count, MPI_Datatype datatype, MPI_Status *status)
{
    int ret = OMPI_SUCCESS;
    OMPI_MPI_OFFSET_TYPE offset = 0;
    long bytesRequested = 0;
    size_t numofBytes;
    struct mca_sharedfp_base_data_t *sh = NULL;
    mca_sharedfp_base_module_t * shared_fp_base_module = NULL;

    if( NULL == fh->f_sharedfp_data){
	if ( mca_sharedfp_sm_verbose ) {
	    printf("sharedfp_sm_read - opening the shared file pointer\n");
	}
        shared_fp_base_module = fh->f_sharedfp;

        ret = shared_fp_base_module->sharedfp_file_open(fh->f_comm,
                                                        fh->f_filename,
                                                        fh->f_amode,
                                                        fh->f_info,
                                                        fh);
        if (  OMPI_SUCCESS != ret ) {
            opal_output(1,"sharedfp_sm_read - error opening the shared file pointer\n");
            return ret;
        }
    }

    /* Calculate the number of bytes to write */
    opal_datatype_type_size ( &datatype->super, &numofBytes);
    bytesRequested = count * numofBytes;

    /* Retrieve the shared file data struct */
    sh = fh->f_sharedfp_data;

    if ( mca_sharedfp_sm_verbose ) {
	printf("sharedfp_sm_read: Bytes Requested is %ld\n",bytesRequested);
    }

    /*Request the offset to write bytesRequested bytes*/
    ret = mca_sharedfp_sm_request_position(sh,bytesRequested,&offset);

    if (  -1 != ret ) {
	if ( mca_sharedfp_sm_verbose ) {
	    printf("sharedfp_sm_read: Offset received is %lld\n",offset);
	}

        /* Read the file */
        ret = ompio_io_ompio_file_read_at(sh->sharedfh,offset,buf,count,datatype,status);
    }

    return ret;
}

int mca_sharedfp_sm_read_ordered (mca_io_ompio_file_t *fh,
                                  void *buf,
                                  int count,
                                  struct ompi_datatype_t *datatype,
                                  ompi_status_public_t *status)
{
    int ret = OMPI_SUCCESS;
    OMPI_MPI_OFFSET_TYPE offset = 0;
    long sendBuff = 0;
    long *buff=NULL;
    long offsetBuff;
    OMPI_MPI_OFFSET_TYPE offsetReceived = 0;
    long bytesRequested = 0;
    int recvcnt = 1, sendcnt = 1;
    size_t numofBytes;
    int rank, size, i;
    struct mca_sharedfp_base_data_t *sh = NULL;
    mca_sharedfp_base_module_t * shared_fp_base_module = NULL;

    if ( NULL == fh->f_sharedfp_data){
 	if ( mca_sharedfp_sm_verbose ) {
	    printf("sharedfp_sm_read_ordered: opening the shared file pointer\n");
	}
        shared_fp_base_module = fh->f_sharedfp;

        ret = shared_fp_base_module->sharedfp_file_open(fh->f_comm,
                                                        fh->f_filename,
                                                        fh->f_amode,
                                                        fh->f_info,
                                                        fh);
        if (  OMPI_SUCCESS != ret ) {
            opal_output(1,"sharedfp_sm_read_ordered - error opening the shared file pointer\n");
            return ret;
        }
    }

    /*Retrieve the new communicator*/
    sh = fh->f_sharedfp_data;

    /* Calculate the number of bytes to read*/
    opal_datatype_type_size ( &datatype->super, &numofBytes);
    sendBuff = count * numofBytes;

    /* Get the ranks in the communicator */
    rank = ompi_comm_rank ( sh->comm );
    size = ompi_comm_size ( sh->comm );

    if ( 0  == rank ) {
        buff = (long*)malloc(sizeof(long) * size);
        if (  NULL == buff )
            return OMPI_ERR_OUT_OF_RESOURCE;
    }

    ret = sh->comm->c_coll.coll_gather ( &sendBuff, sendcnt, OMPI_OFFSET_DATATYPE,
					 buff, recvcnt, OMPI_OFFSET_DATATYPE, 0,
					 sh->comm, sh->comm->c_coll.coll_gather_module );
    if( OMPI_SUCCESS != ret){
	goto exit;
    }

    /* All the counts are present now in the recvBuff.
    ** The size of recvBuff is sizeof_newComm
    */
    if (  0 == rank ) {
        for (i = 0; i < size ; i ++) {
	    bytesRequested += buff[i];
	    if ( mca_sharedfp_sm_verbose ) {
		printf("mca_sharedfp_sm_read_ordered: Bytes requested are %ld\n",bytesRequested);
	    }
        }

        /* Request the offset to read bytesRequested bytes
	** only the root process needs to do the request,
	** since the root process will then tell the other
	** processes at what offset they should read their
	** share of the data.
	*/
        ret = mca_sharedfp_sm_request_position(sh,bytesRequested,&offsetReceived);
        if( OMPI_SUCCESS != ret){
	    goto exit;
        }
	if ( mca_sharedfp_sm_verbose ) {
	    printf("mca_sharedfp_sm_read_ordered: Offset received is %lld\n",offsetReceived);
	}

        buff[0] += offsetReceived;
        for (i = 1 ; i < size; i++)  {
            buff[i] += buff[i-1];
        }
    }

    /* Scatter the results to the other processes*/
    ret = sh->comm->c_coll.coll_scatter ( buff, sendcnt, OMPI_OFFSET_DATATYPE,
					  &offsetBuff, recvcnt, OMPI_OFFSET_DATATYPE, 0,
					  sh->comm, sh->comm->c_coll.coll_scatter_module );
    if( OMPI_SUCCESS != ret){
	goto exit;
    }

    /*Each process now has its own individual offset in recvBUFF*/
    offset = offsetBuff - sendBuff;
    if ( mca_sharedfp_sm_verbose ) {
	printf("mca_sharedfp_sm_read_ordered: Offset returned is %lld\n",offset);
    }

    /* read to the file */
    ret = ompio_io_ompio_file_read_at_all(sh->sharedfh,offset,buf,count,datatype,status);

exit:
    if ( NULL != buff ) {
	free ( buff );
    }

    return ret;
}