.\" Copyright (C) 2021 Stefan Roesch <shr@fb.com>
.\"
.\" SPDX-License-Identifier: LGPL-2.0-or-later
.\"
.TH io_uring_wait_cqe 3 "November 15, 2021" "liburing-2.1" "liburing Manual"
.SH NAME
io_uring_wait_cqe \- wait for one io_uring completion event
.SH SYNOPSIS
.nf
.B #include <liburing.h>
.PP
.BI "int io_uring_wait_cqe(struct io_uring *" ring ","
.BI "                      struct io_uring_cqe **" cqe_ptr ");"
.fi
.SH DESCRIPTION
.PP
The
.BR io_uring_wait_cqe (3)
function waits for an IO completion from the queue belonging to the
.I ring
param, waiting for it if necessary. If an event is already available in
the ring when invoked, no waiting will occur. The
.I cqe_ptr
param is filled in on success.

After the caller has submitted a request with
.BR io_uring_submit (3),
the application can retrieve the completion with
.BR io_uring_wait_cqe (3).

.SH RETURN VALUE
On success
.BR io_uring_wait_cqe (3)
returns 0 and the cqe_ptr param is filled in. On failure it returns
.BR -errno .
The return value indicates the result of waiting for a CQE, and it has no
relation to the CQE result itself.
.SH SEE ALSO
.BR io_uring_submit (3),
.BR io_uring_wait_cqe_timeout (3),
.BR io_uring_wait_cqes (3)