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man/io_uring_for_each_cqe.3
63 строки
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Ammar Faizi
man/io_uring_for_each_cqe: Explicitly tell it's a macro and add an example
09 июн 2023, 06:00
09 июн 2023, 06:00
298c083
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.\" Copyright (C) 2023 Jens Axboe <axboe@kernel.dk> .\" .\" SPDX-License-Identifier: LGPL-2.0-or-later .\" .TH io_uring_for_each_cqe 3 "June 04, 2023" "liburing-2.4" "liburing Manual" .SH NAME io_uring_for_each_cqe \- iterate pending completion events .SH SYNOPSIS .nf .B #include <liburing.h> .PP .BI "io_uring_for_each_cqe(struct io_uring *" ring "," .BI " unsigned " head "," .BI " struct io_uring_cqe *" cqe ") { } .fi .SH DESCRIPTION .PP The .BR io_uring_for_each_cqe (3) is a macro helper that iterates completion events belonging to the .I ring using .I head as a temporary iterator, and points .I cqe to each pending event when iterating. This helper provides an efficient way to iterate all pending events in the ring, and then advancing the CQ ring by calling .BR io_uring_cq_advance (3) with the number of CQEs consumed when done. As updating the kernel visible CQ ring state involves an ordered write, doing it once for a number of events is more efficient than handling each completion separately and calling .BR io_uring_cqe_seen (3) for each of them. .SH EXAMPLE .EX void handle_cqes(struct io_uring *ring) { struct io_uring_cqe *cqe; unsigned head; unsigned i = 0; io_uring_for_each_cqe(ring, head, cqe) { /* handle completion */ printf("cqe: %d\\n", cqe->res); i++; } io_uring_cq_advance(ring, i); } .EE .SH RETURN VALUE None .SH SEE ALSO .BR io_uring_wait_cqe_timeout (3), .BR io_uring_wait_cqe (3), .BR io_uring_wait_cqes (3), .BR io_uring_cqe_seen (3), .BR io_uring_buf_ring_cq_advance (3)