Issuing I/O operations

Once initialized, ABT-IO can be used to issue I/O operations as follows.

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <abt-io.h>

int main(int argc, char** argv)
{
    // Argobots must be initialized, either with ABT_init
    // or with margo_init, thallium::engine, or thallium::abt.
    ABT_init(argc, argv);

    // abt_io_init takes the number of ES to create as a parameter.
    abt_io_instance_id abtio = abt_io_init(2);

    // open a file
    int fd = abt_io_open(abtio, "test.txt", O_WRONLY | O_APPEND | O_CREAT, 0600);

    // write to the file
    abt_io_pwrite(abtio, fd, "This is a test", 14, 0);

    // close the file
    abt_io_close(abtio, fd);

    // ABT-IO must be finalized before Argobots it finalized.
    abt_io_finalize(abtio);

    ABT_finalize();

    return 0;
}

The list of available I/O operations is the following.

ABT-IO function	Corresponding POSIX function
abt_io_open	open
abt_io_write	write
abt_io_pwrite	pwrite
abt_io_read	read
abt_io_pread	pread
abt_io_mkostemp	mkostemp
abt_io_unlink	unlink
abt_io_close	close
abt_io_ftruncate	ftruncate
abt_io_truncate	truncate
abt_io_lseek	lseek
abt_io_fdatasync	fdatasync
abt_io_fallocate	fallocate
abt_io_stat	stat
abt_io_statfs	statfs

Important

We highly recommend using the pwrite and pread wrappers rather than the write, read, and lseek wrappers. The former functions include explicit offsets with each operation, while the latter rely on implicit file positioning which will be unreliable and unpredictable if current I/O operations are in flight. ABT-IO inherently does not serialize or otherwise enforce ordering among concurrent operations.