/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2011 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) 2008-2014 University of Houston. All rights reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 */

/* This code is based on the PVFS2 ADIO module in ROMIO
 *   Copyright (C) 1997 University of Chicago.
 *   See COPYRIGHT notice in top-level directory.
 */

#include "ompi_config.h"
#include "fbtl_pvfs2.h"

#include "mpi.h"
#include <unistd.h>
#include "ompi/constants.h"
#include "ompi/mca/fbtl/fbtl.h"

ssize_t  mca_fbtl_pvfs2_preadv (mca_io_ompio_file_t *fh)
{
    int i;
    int ret;
    size_t k;
    int merge = 0;
    char *merge_buf = NULL;
    size_t merge_length = 0;
    OMPI_MPI_OFFSET_TYPE merge_offset = 0;
    PVFS_sysresp_io resp_io;
    PVFS_Request file_req;
    PVFS_Request mem_req;
    mca_fs_pvfs2 *pvfs2_fs;
    ssize_t total_bytes_read=0;

    pvfs2_fs = (mca_fs_pvfs2 *)fh->f_fs_ptr;

    if (NULL == fh->f_io_array) {
        return OMPI_ERROR;
    }

    for (i=0 ; i<fh->f_num_of_io_entries ; i++) {
	if (fh->f_num_of_io_entries != i+1) {
	    if (((OMPI_MPI_OFFSET_TYPE)fh->f_io_array[i].offset +
		 (OPAL_PTRDIFF_TYPE)fh->f_io_array[i].length) ==
		(OMPI_MPI_OFFSET_TYPE)fh->f_io_array[i+1].offset) {
		if (!merge) {
		    merge_offset = (OMPI_MPI_OFFSET_TYPE)
			fh->f_io_array[i].offset;
		    merge_length = fh->f_io_array[i].length;
		}
		merge_length += fh->f_io_array[i+1].length;
		merge++;
		continue;
	    }
	}
	if (merge) {
	    merge_buf = malloc (merge_length);

	    ret = PVFS_Request_contiguous (merge_length,
					   PVFS_BYTE,
					   &mem_req);
	    if (ret != 0) {
		perror("PVFS_Request_contiguous() error");
		return OMPI_ERROR;
	    }
	    ret = PVFS_Request_contiguous (merge_length,
					   PVFS_BYTE,
					   &file_req);
	    if (ret != 0) {
		perror("PVFS_Request_contiguous() error");
		return OMPI_ERROR;
	    }
	    ret = PVFS_sys_read (pvfs2_fs->object_ref,
				 file_req,
				 merge_offset,
				 merge_buf,
				 mem_req,
				 &(pvfs2_fs->credentials),
				 &resp_io);
	    if (ret != 0) {
		perror("PVFS_sys_write() error");
		return OMPI_ERROR;
	    }
	    total_bytes_read += (ssize_t)resp_io.total_completed;

	    k = 0;
	    while (merge >= 0) {
		memcpy (fh->f_io_array[i-merge].memory_address,
			merge_buf + k,
			fh->f_io_array[i-merge].length);
		k += fh->f_io_array[i-merge].length;
		merge --;
	    }
	    merge = 0;
	    merge_offset = 0;
	    merge_length = 0;
	    if (NULL != merge_buf) {
		free (merge_buf);
		merge_buf = NULL;
	    }
	}
	else {
	    ret = PVFS_Request_contiguous (fh->f_io_array[i].length,
					   PVFS_BYTE,
					   &mem_req);
	    if (ret != 0) {
		perror("PVFS_Request_contiguous() error");
		return OMPI_ERROR;
	    }
	    ret = PVFS_Request_contiguous (fh->f_io_array[i].length,
					   PVFS_BYTE,
					   &file_req);
	    if (ret != 0) {
		perror("PVFS_Request_contiguous() error");
		return OMPI_ERROR;
	    }
	    ret = PVFS_sys_read (pvfs2_fs->object_ref,
				 file_req,
				 (OMPI_MPI_OFFSET_TYPE)
				 fh ->f_io_array[i].offset,
				 fh->f_io_array[i].memory_address,
				 mem_req,
				 &(pvfs2_fs->credentials),
				 &resp_io);
	    if (ret != 0) {
		perror("PVFS_sys_write() error");
		return OMPI_ERROR;
	    }
	    total_bytes_read += (ssize_t)resp_io.total_completed;
	}
    }

    return total_bytes_read;
}
