libev/ev_epoll.c

/*
 * libev epoll fd activity backend
 *
 * Copyright (c) 2007 Marc Alexander Lehmann <libev@schmorp.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * Redistributions in binary form must reproduce the above
 *       copyright notice, this list of conditions and the following
 *       disclaimer in the documentation and/or other materials provided
 *       with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/epoll.h>

static void
epoll_modify (EV_P_ int fd, int oev, int nev)
{
  int mode = nev ? oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL;

  struct epoll_event ev;
  ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */
  ev.events =
      (nev & EV_READ ? EPOLLIN : 0)
      | (nev & EV_WRITE ? EPOLLOUT : 0);

  if (expect_false (epoll_ctl (backend_fd, mode, fd, &ev)))
    if (errno != ENOENT /* on ENOENT the fd went away, so try to do the right thing */
        || (nev && epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)))
      fd_kill (EV_A_ fd);
}

static void
epoll_poll (EV_P_ ev_tstamp timeout)
{
  int i;
  int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.));

  if (expect_false (eventcnt < 0))
    {
      if (errno != EINTR)
        syserr ("(libev) epoll_wait");

      return;
    }

  for (i = 0; i < eventcnt; ++i)
    fd_event (
      EV_A_
      epoll_events [i].data.u64,
      (epoll_events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
      | (epoll_events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0)
    );

  /* if the receive array was full, increase its size */
  if (expect_false (eventcnt == epoll_eventmax))
    {
      ev_free (epoll_events);
      epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1);
      epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
    }
}

int inline_size
epoll_init (EV_P_ int flags)
{
  backend_fd = epoll_create (256);

  if (backend_fd < 0)
    return 0;

  fcntl (backend_fd, F_SETFD, FD_CLOEXEC);

  backend_fudge  = 2e-4; /* needed to compensate for epoll returning early */
  backend_modify = epoll_modify;
  backend_poll   = epoll_poll;

  epoll_eventmax = 64; /* intiial number of events receivable per poll */
  epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);

  return EVBACKEND_EPOLL;
}

void inline_size
epoll_destroy (EV_P)
{
  ev_free (epoll_events);
}

void inline_size
epoll_fork (EV_P)
{
  close (backend_fd);

  while ((backend_fd = epoll_create (256)) < 0)
    syserr ("(libev) epoll_create");

  fcntl (backend_fd, F_SETFD, FD_CLOEXEC);

  fd_rearm_all (EV_A);
}

Revision:	1.30
Committed:	Sun Dec 9 03:19:50 2007 UTC (16 years, 5 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.29:	+1 -1 lines
Log Message:	reduce fudge - it certainly isn't 0 in principle, but 0 in practise everywhere i could test
#	User	Rev	Content
1	root	1.5	/*
2	root	1.9	* libev epoll fd activity backend
3			*
4	root	1.5	* Copyright (c) 2007 Marc Alexander Lehmann <libev@schmorp.de>
5			* All rights reserved.
6			*
7			* Redistribution and use in source and binary forms, with or without
8			* modification, are permitted provided that the following conditions are
9			* met:
10			*
11			* * Redistributions of source code must retain the above copyright
12			* notice, this list of conditions and the following disclaimer.
13			*
14			* * Redistributions in binary form must reproduce the above
15			* copyright notice, this list of conditions and the following
16			* disclaimer in the documentation and/or other materials provided
17			* with the distribution.
18			*
19			* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20			* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21			* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22			* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23			* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24			* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25			* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26			* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27			* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28			* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29			* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30			*/
31
32	root	1.1	#include <sys/epoll.h>
33
34			static void
35	root	1.13	epoll_modify (EV_P_ int fd, int oev, int nev)
36	root	1.1	{
37	root	1.2	int mode = nev ? oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL;
38	root	1.1
39	root	1.2	struct epoll_event ev;
40	root	1.11	ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */
41	root	1.2	ev.events =
42			(nev & EV_READ ? EPOLLIN : 0)
43			\| (nev & EV_WRITE ? EPOLLOUT : 0);
44
45	root	1.29	if (expect_false (epoll_ctl (backend_fd, mode, fd, &ev)))
46	root	1.19	if (errno != ENOENT /* on ENOENT the fd went away, so try to do the right thing */
47	root	1.26	\|\| (nev && epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)))
48	root	1.19	fd_kill (EV_A_ fd);
49	root	1.1	}
50
51	root	1.6	static void
52	root	1.13	epoll_poll (EV_P_ ev_tstamp timeout)
53	root	1.1	{
54	root	1.20	int i;
55	root	1.26	int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.));
56	root	1.1
57	root	1.29	if (expect_false (eventcnt < 0))
58	root	1.20	{
59			if (errno != EINTR)
60	root	1.21	syserr ("(libev) epoll_wait");
61	root	1.20
62			return;
63			}
64	root	1.1
65			for (i = 0; i < eventcnt; ++i)
66			fd_event (
67	root	1.13	EV_A_
68	root	1.14	epoll_events [i].data.u64,
69			(epoll_events [i].events & (EPOLLOUT \| EPOLLERR \| EPOLLHUP) ? EV_WRITE : 0)
70			\| (epoll_events [i].events & (EPOLLIN \| EPOLLERR \| EPOLLHUP) ? EV_READ : 0)
71	root	1.1	);
72
73			/* if the receive array was full, increase its size */
74	root	1.14	if (expect_false (eventcnt == epoll_eventmax))
75	root	1.1	{
76	root	1.20	ev_free (epoll_events);
77	root	1.28	epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1);
78	root	1.23	epoll_events = (struct epoll_event )ev_malloc (sizeof (struct epoll_event) epoll_eventmax);
79	root	1.1	}
80			}
81
82	root	1.27	int inline_size
83	root	1.13	epoll_init (EV_P_ int flags)
84	root	1.1	{
85	root	1.26	backend_fd = epoll_create (256);
86	root	1.1
87	root	1.26	if (backend_fd < 0)
88	root	1.13	return 0;
89	root	1.3
90	root	1.26	fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
91	root	1.1
92	root	1.30	backend_fudge = 2e-4; /* needed to compensate for epoll returning early */
93	root	1.25	backend_modify = epoll_modify;
94			backend_poll = epoll_poll;
95	root	1.1
96	root	1.14	epoll_eventmax = 64; /* intiial number of events receivable per poll */
97	root	1.23	epoll_events = (struct epoll_event )ev_malloc (sizeof (struct epoll_event) epoll_eventmax);
98	root	1.13
99	root	1.24	return EVBACKEND_EPOLL;
100	root	1.1	}
101	root	1.6
102	root	1.27	void inline_size
103	root	1.15	epoll_destroy (EV_P)
104			{
105	root	1.20	ev_free (epoll_events);
106	root	1.15	}
107
108	root	1.27	void inline_size
109	root	1.15	epoll_fork (EV_P)
110			{
111	root	1.26	close (backend_fd);
112	root	1.21
113	root	1.26	while ((backend_fd = epoll_create (256)) < 0)
114	root	1.22	syserr ("(libev) epoll_create");
115	root	1.21
116	root	1.26	fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
117	root	1.15
118	root	1.16	fd_rearm_all (EV_A);
119	root	1.15	}
120