man/io_uring_submit_and_wait_timeout.3

.\" Copyright (C) 2021 Stefan Roesch <shr@fb.com>
.\"
.\" SPDX-License-Identifier: LGPL-2.0-or-later
.\"
.TH io_uring_submit_and_wait_timeout 3 "November 15, 2021" "liburing-2.1" "liburing Manual"
.SH NAME
io_uring_submit_and_wait_timeout \- submit requests to the submission queue and
wait for the completion with timeout
.SH SYNOPSIS
.nf
.B #include <liburing.h>
.PP
.BI "int io_uring_submit_and_wait_timeout(struct io_uring *" ring ","
.BI "                                     struct io_uring_cqe **" cqe_ptr ","
.BI "                                     unsigned " wait_nr ","
.BI "                                     struct __kernel_timespec *" ts ","
.BI "                                     sigset_t *" sigmask ");"
.fi
.SH DESCRIPTION
.PP
The
.BR io_uring_submit_and_wait_timeout (3)
function submits the next requests from the submission queue belonging to the
.I ring
and waits for
.I wait_nr
completion events, or until the timeout
.I ts
expires. The completion events are stored in the
.I cqe_ptr
array.
.PP
The
.I sigmask
specifies the set of signals to block. If set, it is equivalent to atomically
executing the following calls:
.PP
.in +4n
.EX
sigset_t origmask;

pthread_sigmask(SIG_SETMASK, &sigmask, &origmask);
ret = io_uring_submit_and_wait_timeout(ring, cqe, wait_nr, ts, NULL);
pthread_sigmask(SIG_SETMASK, &origmask, NULL);
.EE
.in
.PP
After the caller retrieves a submission queue entry (SQE) with
.BR io_uring_get_sqe (3)
and prepares the SQE, it can be submitted with
.BR io_uring_submit_and_wait_timeout (3) .

Ideally used with a ring setup with
.BR IORING_SETUP_SINGLE_ISSUER | IORING_SETUP_DEFER_TASKRUN
as that will greatly reduce the number of context switches that an application
will see waiting on multiple requests.

.SH RETURN VALUE
On success
.BR io_uring_submit_and_wait_timeout (3)
returns the number of submitted submission queue entries. On failure it returns
.BR -errno .
Note that in earlier versions of the liburing library, the return value was 0
on success.
The most common failure case is not receiving a completion within the specified
timeout,
.B -ETIME
is returned in this case.
.SH SEE ALSO
.BR io_uring_queue_init_params (3),
.BR io_uring_get_sqe (3),
.BR io_uring_submit (3),
.BR io_uring_submit_and_wait (3),
.BR io_uring_wait_cqe (3)