openmpi/ompi/mca/sharedfp/lockedfile/sharedfp_lockedfile_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) 2013-2015 University of Houston. All rights reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 */


#include "ompi_config.h"
#include "sharedfp_lockedfile.h"

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

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

    if ( fh->f_sharedfp_data == NULL ) {
	if ( mca_sharedfp_lockedfile_verbose ) {
            opal_output(ompi_sharedfp_base_framework.framework_output,
                        "sharedfp_lockedfile_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(0,"sharedfp_lockedfile_read - error opening the shared file pointer\n");
            return ret;
        }
    }

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

    if ( mca_sharedfp_lockedfile_verbose ) {
        opal_output(ompi_sharedfp_base_framework.framework_output,
                    "sharedfp_lockedfile_read: Bytes Requested is %ld\n",bytesRequested);
    }

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

    /*Request the offset to write bytesRequested bytes*/
    ret = mca_sharedfp_lockedfile_request_position(sh,bytesRequested,&offset);
    offset /= sh->sharedfh->f_etype_size;

    if (-1 != ret )  {
	if ( mca_sharedfp_lockedfile_verbose ) {
            opal_output(ompi_sharedfp_base_framework.framework_output,
                        "sharedfp_lockedfile_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_lockedfile_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;
    mca_sharedfp_base_module_t * shared_fp_base_module=NULL;
    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;

    if ( fh->f_sharedfp_data == NULL){
	if ( mca_sharedfp_lockedfile_verbose ) {
            opal_output(ompi_sharedfp_base_framework.framework_output,
                        "sharedfp_lockedfile_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(0,"sharedfp_lockedfile_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_lockedfile_verbose ) {
                opal_output(ompi_sharedfp_base_framework.framework_output,
                            "sharedfp_lockedfile_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_lockedfile_request_position(sh,bytesRequested,&offsetReceived);
        if( OMPI_SUCCESS != ret ){
            goto exit;
        }
	if ( mca_sharedfp_lockedfile_verbose ) {
            opal_output(ompi_sharedfp_base_framework.framework_output,
                        "sharedfp_lockedfile_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 );

    /*Each process now has its own individual offset in recvBUFF*/
    offset = offsetBuff - sendBuff;
    offset /= sh->sharedfh->f_etype_size;

    if ( mca_sharedfp_lockedfile_verbose ) {
        opal_output(ompi_sharedfp_base_framework.framework_output,
                    "sharedfp_lockedfile_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;
}