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libwebsockets/lib/plat/unix/unix-pipe.c
Oliver Langlois 17357ddd5a unix plat: use eventfd in place of pipe where possible
From eventfd man page:
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).
2020-02-09 05:48:16 +00:00

70 lines
1.9 KiB
C

/*
* libwebsockets - small server side websockets and web server implementation
*
* Copyright (C) 2010-2018 Andy Green <andy@warmcat.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation:
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*/
#define _GNU_SOURCE
#include "core/private.h"
int
lws_plat_pipe_create(struct lws *wsi)
{
struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
#if defined(LWS_HAVE_EVENTFD)
pt->dummy_pipe_fds[0] = eventfd(0, EFD_CLOEXEC|EFD_NONBLOCK);
pt->dummy_pipe_fds[1] = -1;
return pt->dummy_pipe_fds[0]<0?-1:0;
#elif defined(LWS_HAVE_PIPE2)
return pipe2(pt->dummy_pipe_fds, O_NONBLOCK);
#else
return pipe(pt->dummy_pipe_fds);
#endif
}
int
lws_plat_pipe_signal(struct lws *wsi)
{
struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
#if defined(LWS_HAVE_EVENTFD)
eventfd_t value = 1;
return eventfd_write(pt->dummy_pipe_fds[0], value);
#else
char buf = 0;
int n;
n = write(pt->dummy_pipe_fds[1], &buf, 1);
return n != 1;
#endif
}
void
lws_plat_pipe_close(struct lws *wsi)
{
struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
if (pt->dummy_pipe_fds[0] && pt->dummy_pipe_fds[0] != -1)
close(pt->dummy_pipe_fds[0]);
if (pt->dummy_pipe_fds[1] && pt->dummy_pipe_fds[1] != -1)
close(pt->dummy_pipe_fds[1]);
pt->dummy_pipe_fds[0] = pt->dummy_pipe_fds[1] = -1;
}