NAME

       nbd_aio_peek_command_completed - check if any command has completed

SYNOPSIS

        #include <libnbd.h>

        int64_t nbd_aio_peek_command_completed (struct nbd_handle *h);

DESCRIPTION

       Return the unique positive 64 bit cookie of the first non-retired but completed command, 0
       if there are in-flight commands but none of them are awaiting retirement, or "-1" on error
       including when there are no in-flight commands. Any cookie returned by this function must
       still be passed to nbd_aio_command_completed(3) to actually retire the command and learn
       whether the command was successful.

RETURN VALUE

       This call returns a 64 bit signed integer ≥ 0.

ERRORS

       On error "-1" is returned.

       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details of the error.

       The following parameters must not be NULL: "h".  For more information see "Non-NULL
       parameters" in libnbd(3).

VERSION

       This function first appeared in libnbd 1.0.

       If you need to test if this function is available at compile time check if the following
       macro is defined:

        #define LIBNBD_HAVE_NBD_AIO_PEEK_COMMAND_COMPLETED 1

SEE ALSO

       nbd_aio_command_completed(3), nbd_create(3), libnbd(3).

AUTHORS

       Eric Blake

       Richard W.M. Jones

COPYRIGHT

       Copyright (C) 2019-2021 Red Hat Inc.

LICENSE

       This library is free software; you can redistribute it and/or modify it under the terms of
       the GNU Lesser General Public License as published by the Free Software Foundation; either
       version 2 of the License, or (at your option) any later version.

       This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
       without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
       See the GNU Lesser General Public License for more details.

       You should have received a copy of the GNU Lesser General Public License along with this
       library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
       Floor, Boston, MA 02110-1301 USA