23fe1a52dc
Currently, we use `pipe` for `wakeup_create`, which requires ***two***
file descriptors. Furthermore, given its complexity inside, `pipe` is a
bit heavyweight for just a simple event wait/notify mechanism.
`eventfd` would be a more suitable solution for this kind of scenario,
kernel also advocates for developers to use `eventfd` instead of `pipe`
in some simple use cases:
Applications can use an eventfd file descriptor instead of a pipe
(see pipe(2) in all cases where a pipe is used simply to signal
events. The kernel overhead of an eventfd file descriptor is much
lower than that of a pipe, and only one file descriptor is required
(versus the two required for a pipe).
This change adds the new backend of `eventfd` for `wakeup_create` and
uses it where available, eliminating the overhead of `pipe`. Also, it
optimizes the `wakeup_create` to eliminate the system calls that make
file descriptors non-blocking by moving the logic of setting
non-blocking flags on file descriptors to `socketpair.c` and using
`SOCK_NONBLOCK` for `socketpair(2)`, `EFD_NONBLOCK` for `eventfd(2)`.
Ref:
https://man7.org/linux/man-pages/man7/pipe.7.html
https://man7.org/linux/man-pages/man2/eventfd.2.html
https://man7.org/linux/man-pages/man2/socketpair.2.html
https://www.gnu.org/software/gnulib/manual/html_node/eventfd.html
Closes #13874
96 lines
3.0 KiB
C
96 lines
3.0 KiB
C
#ifndef HEADER_CURL_SOCKETPAIR_H
|
|
#define HEADER_CURL_SOCKETPAIR_H
|
|
/***************************************************************************
|
|
* _ _ ____ _
|
|
* Project ___| | | | _ \| |
|
|
* / __| | | | |_) | |
|
|
* | (__| |_| | _ <| |___
|
|
* \___|\___/|_| \_\_____|
|
|
*
|
|
* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
|
|
*
|
|
* This software is licensed as described in the file COPYING, which
|
|
* you should have received as part of this distribution. The terms
|
|
* are also available at https://curl.se/docs/copyright.html.
|
|
*
|
|
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
|
|
* copies of the Software, and permit persons to whom the Software is
|
|
* furnished to do so, under the terms of the COPYING file.
|
|
*
|
|
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
|
|
* KIND, either express or implied.
|
|
*
|
|
* SPDX-License-Identifier: curl
|
|
*
|
|
***************************************************************************/
|
|
|
|
#include "curl_setup.h"
|
|
|
|
#if defined(HAVE_EVENTFD) && \
|
|
defined(__x86_64__) && \
|
|
defined(__aarch64__) && \
|
|
defined(__ia64__) && \
|
|
defined(__ppc64__) && \
|
|
defined(__mips64) && \
|
|
defined(__sparc64__) && \
|
|
defined(__riscv_64e) && \
|
|
defined(__s390x__)
|
|
|
|
/* Use eventfd only with 64-bit CPU architectures because eventfd has a
|
|
* stringent rule of requiring the 8-byte buffer when calling read(2) and
|
|
* write(2) on it. In some rare cases, the C standard library implementation
|
|
* on a 32-bit system might choose to define uint64_t as a 32-bit type for
|
|
* various reasons (memory limitations, compatibility with older code),
|
|
* which makes eventfd broken.
|
|
*/
|
|
#define USE_EVENTFD 1
|
|
|
|
#define wakeup_write write
|
|
#define wakeup_read read
|
|
#define wakeup_close close
|
|
#define wakeup_create(p,nb) Curl_eventfd(p,nb)
|
|
|
|
#include <curl/curl.h>
|
|
int Curl_eventfd(curl_socket_t socks[2], bool nonblocking);
|
|
|
|
#elif defined(HAVE_PIPE)
|
|
|
|
#define wakeup_write write
|
|
#define wakeup_read read
|
|
#define wakeup_close close
|
|
#define wakeup_create(p,nb) Curl_pipe(p,nb)
|
|
|
|
#include <curl/curl.h>
|
|
int Curl_pipe(curl_socket_t socks[2], bool nonblocking);
|
|
|
|
#else /* HAVE_PIPE */
|
|
|
|
#define wakeup_write swrite
|
|
#define wakeup_read sread
|
|
#define wakeup_close sclose
|
|
|
|
#if defined(USE_UNIX_SOCKETS) && defined(HAVE_SOCKETPAIR)
|
|
#define SOCKETPAIR_FAMILY AF_UNIX
|
|
#elif !defined(HAVE_SOCKETPAIR)
|
|
#define SOCKETPAIR_FAMILY 0 /* not used */
|
|
#else
|
|
#error "unsupported unix domain and socketpair build combo"
|
|
#endif
|
|
|
|
#ifdef SOCK_CLOEXEC
|
|
#define SOCKETPAIR_TYPE (SOCK_STREAM | SOCK_CLOEXEC)
|
|
#else
|
|
#define SOCKETPAIR_TYPE SOCK_STREAM
|
|
#endif
|
|
|
|
#define wakeup_create(p,nb)\
|
|
Curl_socketpair(SOCKETPAIR_FAMILY, SOCKETPAIR_TYPE, 0, p, nb)
|
|
|
|
#endif /* HAVE_PIPE */
|
|
|
|
#include <curl/curl.h>
|
|
|
|
int Curl_socketpair(int domain, int type, int protocol,
|
|
curl_socket_t socks[2], bool nonblocking);
|
|
#endif /* HEADER_CURL_SOCKETPAIR_H */
|