/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
/* 
 *
 *   Copyright (C) 2007 UChicago/Argonne LLC
 *   See COPYRIGHT notice in top-level directory.
 */

#include "adio.h"


/* this "collective" open is useful for frankly broken file systems such
 * as NFS where a create from one client might not be immediately
 * visible on another */

void ADIOI_FAILSAFE_OpenColl(ADIO_File fd, int rank, 
	int access_mode, int *error_code)
{
    MPI_Comm tmp_comm;
    int orig_amode_excl, orig_amode_wronly;

    orig_amode_excl = access_mode;
    if ((access_mode & ADIO_CREATE) && (access_mode & ADIO_EXCL)) {
	/* the open should fail if the file exists. Only *1* process
	 * should check this. Otherwise, if all processes try to check
	 * and the file does not exist, one process will create the file
	 * and others who reach later will return error. */ 
	if(rank == fd->hints->ranklist[0]) {
	    fd->access_mode = access_mode;

	    /* if the lower-level file system tries to communicate, COMM_SELF
	     * will ensure it doesn't get stuck waiting for non-existant
	     * participants */
	    tmp_comm = fd->comm;
	    fd->comm = MPI_COMM_SELF;
	    (*(fd->fns->ADIOI_xxx_Open))(fd, error_code);
	    MPI_Bcast(error_code, 1, MPI_INT, \
		    fd->hints->ranklist[0], tmp_comm);
	    /* if no error, close the file and reopen normally below */
	    if (*error_code == MPI_SUCCESS)
		(*(fd->fns->ADIOI_xxx_Close))(fd, error_code);
	    /* and put it all back the way we found it for subsequent code */
	    fd->comm = tmp_comm;
	}
	else MPI_Bcast(error_code, 1, MPI_INT,
		fd->hints->ranklist[0], fd->comm);
	if (*error_code != MPI_SUCCESS) {
	    return;
	}
	else {
	    /* turn off EXCL for real open */
	    access_mode = access_mode ^ ADIO_EXCL;
	}
    }
    /* if we are doing deferred open, non-aggregators should return now */
    if (fd->hints->deferred_open && !(fd->is_agg)) {
	/* we might have turned off EXCL for the aggregators.
	 * restore access_mode that non-aggregators get the right
	 * value from get_amode */
	fd->access_mode = orig_amode_excl;
	*error_code = MPI_SUCCESS;
	return;
    }

/* For writing with data sieving, a read-modify-write is needed. If 
   the file is opened for write_only, the read will fail. Therefore,
   if write_only, open the file as read_write, but record it as write_only
   in fd, so that get_amode returns the right answer. */

    orig_amode_wronly = access_mode;
    if (access_mode & ADIO_WRONLY) {
	access_mode = access_mode ^ ADIO_WRONLY;
	access_mode = access_mode | ADIO_RDWR;
    }
    fd->access_mode = access_mode;

    (*(fd->fns->ADIOI_xxx_Open))(fd, error_code);

    /* if error, may be it was due to the change in amode above. 
       therefore, reopen with access mode provided by the user.*/ 
    fd->access_mode = orig_amode_wronly;  
    if (*error_code != MPI_SUCCESS) 
        (*(fd->fns->ADIOI_xxx_Open))(fd, error_code);

    if(*error_code != MPI_SUCCESS) return;
    /* if we turned off EXCL earlier, then we should turn it back on */
    if (fd->access_mode != orig_amode_excl) fd->access_mode = orig_amode_excl;

    /* for deferred open: this process has opened the file (because if we are
     * not an aggregaor and we are doing deferred open, we returned earlier)*/
    fd->is_open = 1;
}



/* 
 * vim: ts=8 sts=4 sw=4 noexpandtab 
 */