=head1 NAME

nbd_aio_command_completed - check if the command completed

=head1 SYNOPSIS

 #include <libnbd.h>

 int nbd_aio_command_completed (
       struct nbd_handle *h, uint64_t cookie
     );

=head1 DESCRIPTION

Return true if the command completed.
If this function returns
true then the command was successful and it has been retired.
Return false if the command is still in flight.  This can also
fail with an error in case the command failed (in this case
the command is also retired).  A command is retired either via
this command, or by using a completion callback which returns C<1>.

The C<cookie> parameter is the positive unique 64 bit cookie
for the command, as returned by a call such as L<nbd_aio_pread(3)>.

=head1 RETURN VALUE

This call returns a boolean value.

=head1 ERRORS

On error C<-1> is returned.

Refer to L<libnbd(3)/ERROR HANDLING>
for how to get further details of the error.

The following parameters must not be NULL: C<h>.
For more information see L<libnbd(3)/Non-NULL parameters>.

=head1 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_COMMAND_COMPLETED 1

=head1 SEE ALSO

L<nbd_aio_pread(3)>,
L<nbd_create(3)>,
L<libnbd(3)>.

=head1 AUTHORS

Eric Blake

Richard W.M. Jones

=head1 COPYRIGHT

Copyright Red Hat
