.\" Copyright (C) 2022 Jens Axboe <axboe@kernel.dk>
.\"
.\" SPDX-License-Identifier: LGPL-2.0-or-later
.\"
.TH io_uring_peek_cqe 3 "March 12, 2022" "liburing-2.2" "liburing Manual"
.SH NAME
io_uring_peek_cqe \- check if an io_uring completion event is available
.SH SYNOPSIS
.nf
.B #include <liburing.h>
.PP
.BI "int io_uring_peek_cqe(struct io_uring *" ring ","
.BI "                      struct io_uring_cqe **" cqe_ptr ");"
.fi
.SH DESCRIPTION
.PP
The
.BR io_uring_peek_cqe (3)
function returns an IO completion from the queue belonging to the
.I ring
param, if one is readily available. On successful return,
.I cqe_ptr
param is filled with a valid CQE entry.

This function does not enter the kernel to wait for an event, an event
is only returned if it's already available in the CQ ring.

.SH RETURN VALUE
On success
.BR io_uring_peek_cqe (3)
returns
.B 0
and the cqe_ptr parameter is filled in. On failure it returns
.BR -EAGAIN .
.SH SEE ALSO
.BR io_uring_submit (3),
.BR io_uring_wait_cqes (3),
.BR io_uring_wait_cqe (3)