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/*
* 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"
#include "opal/util/output.h"
#include "opal/util/fd.h"
/*Use fcntl to lock the hidden file which stores the current position*/
#include <fcntl.h>
#include <unistd.h>
int mca_sharedfp_lockedfile_request_position(struct mca_sharedfp_base_data_t * sh,
int bytes_requested,
OMPI_MPI_OFFSET_TYPE *offset)
{
int ret = OMPI_SUCCESS;
/*file descriptor for the hidden file that we want to lock*/
int fd;
/* flock structure that is used to setup the desired fcntl operation */
struct flock fl;
OMPI_MPI_OFFSET_TYPE position = 0;
/*buffer to use when reading from the locked file*/
OMPI_MPI_OFFSET_TYPE buf;
/*int count = 1;*/
struct mca_sharedfp_lockedfile_data * lockedfile_data = sh->selected_module_data;
int handle = lockedfile_data->handle;
*offset = 0;
/* get the saved file descriptor,
* the hidden file was opened during sharedfp_lockedfile_file_open function */
fd = handle;
/*set up the flock structure*/
fl.l_type = F_WRLCK;
fl.l_whence = SEEK_SET;
fl.l_start = 0;
fl.l_len = 0;
fl.l_pid = getpid();
/* Acquire an exclusive lock */
if (fcntl(fd, F_SETLKW, &fl) == -1) {
opal_output(0,"sharedfp_lockedfile_request_position: error acquiring lock: fcntl(%d,F_SETLKW,&fl)\n",fd);
opal_output(0,"sharedfp_lockedfile_request_position: error(%i): %s", errno, strerror(errno));
return OMPI_ERROR;
}
else{
if ( mca_sharedfp_lockedfile_verbose ) {
opal_output(ompi_sharedfp_base_framework.framework_output,
"sharedfp_lockedfile_request_position: Success: acquired lock.for fd: %d\n",fd);
}
}
/* read from the file */
lseek ( fd, 0, SEEK_SET );
ret = opal_fd_read ( fd, sizeof(OMPI_MPI_OFFSET_TYPE), &buf);
if (OPAL_SUCCESS != ret ) {
goto exit;
}
if ( mca_sharedfp_lockedfile_verbose ) {
opal_output(ompi_sharedfp_base_framework.framework_output,
"sharedfp_lockedfile_request_position: Read last_offset=%lld! ret=%d\n",buf, ret);
}
/* increment the position */
position = buf + bytes_requested;
if ( mca_sharedfp_lockedfile_verbose ) {
opal_output(ompi_sharedfp_base_framework.framework_output,
"sharedfp_lockedfile_request_position: old_offset=%lld, bytes_requested=%d, new offset=%lld!\n",
buf,bytes_requested,position);
}
/* write to the file */
lseek ( fd, 0, SEEK_SET );
ret = opal_best_effort_write ( fd, &position, sizeof(OMPI_MPI_OFFSET_TYPE));
/* No need to handle error case here, the subsequent steps are identical
in case of ret != OPAL_SUCCESS, namely release lock and return ret */
exit:
/* unlock the file */
if ( mca_sharedfp_lockedfile_verbose ) {
opal_output(ompi_sharedfp_base_framework.framework_output,
"sharedfp_lockedfile_request_position: Releasing lock...");
}
/* NOTE: We thought we could reuse the flock struct
** and only reset the l_type parameter, but it gave
** an invalid argument error. On my machine the invalid
** argument was l_whence. I reset it, but I also decided to
** reset all of the other parameters to avoid further problems.
*/
fl.l_type = F_UNLCK; /* set to unlock same region */
fl.l_whence = SEEK_SET;
fl.l_start = 0;
fl.l_len = 0;
fl.l_pid = getpid();
if (fcntl(fd, F_SETLK, &fl) == -1) {
opal_output(0,"sharedfp_lockedfile_request_position:failed to release lock for fd: %d\n",fd);
opal_output(0,"error(%i): %s", errno, strerror(errno));
/* Only overwrite error code if it was OPAL_SUCCESS previously */
if (OPAL_SUCCESS == ret ) {
ret = OMPI_ERROR;
}
}
else {
if ( mca_sharedfp_lockedfile_verbose ) {
opal_output(ompi_sharedfp_base_framework.framework_output,
"sharedfp_lockedfile_request_position: released lock.for fd: %d\n",fd);
}
}
/* return position */
*offset = buf;
return ret;
}
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