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Comparing libev/ev_epoll.c (file contents):
Revision 1.18 by root, Sun Nov 4 22:03:17 2007 UTC vs.
Revision 1.34 by root, Fri May 23 16:37:38 2008 UTC

1/* 1/*
2 * libev epoll fd activity backend 2 * libev epoll fd activity backend
3 * 3 *
4 * Copyright (c) 2007 Marc Alexander Lehmann <libev@schmorp.de> 4 * Copyright (c) 2007,2008 Marc Alexander Lehmann <libev@schmorp.de>
5 * All rights reserved. 5 * All rights reserved.
6 * 6 *
7 * Redistribution and use in source and binary forms, with or without 7 * Redistribution and use in source and binary forms, with or without modifica-
8 * modification, are permitted provided that the following conditions are 8 * tion, are permitted provided that the following conditions are met:
9 * met: 9 *
10 * 1. Redistributions of source code must retain the above copyright notice,
11 * this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
19 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
20 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
21 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
22 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
23 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
24 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
25 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
26 * OF THE POSSIBILITY OF SUCH DAMAGE.
10 * 27 *
11 * * Redistributions of source code must retain the above copyright 28 * Alternatively, the contents of this file may be used under the terms of
12 * notice, this list of conditions and the following disclaimer. 29 * the GNU General Public License ("GPL") version 2 or any later version,
30 * in which case the provisions of the GPL are applicable instead of
31 * the above. If you wish to allow the use of your version of this file
32 * only under the terms of the GPL and not to allow others to use your
33 * version of this file under the BSD license, indicate your decision
34 * by deleting the provisions above and replace them with the notice
35 * and other provisions required by the GPL. If you do not delete the
36 * provisions above, a recipient may use your version of this file under
37 * either the BSD or the GPL.
38 */
39
40/*
41 * general notes about epoll:
13 * 42 *
14 * * Redistributions in binary form must reproduce the above 43 * a) epoll silently removes fds from the fd set. as nothing tells us
15 * copyright notice, this list of conditions and the following 44 * that an fd has been removed otherwise, we have to continually
16 * disclaimer in the documentation and/or other materials provided 45 * "rearm" fds that we suspect *might* have changed (same
17 * with the distribution. 46 * problem with kqueue, but much less costly there).
47 * b) the fact that ADD != MOD creates a lot of extra syscalls due to a)
48 * and seems not to have any advantage.
49 * c) the inability to handle fork or file descriptors (think dup)
50 * limits the applicability over poll, so this is not a generic
51 * poll replacement.
18 * 52 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 53 * lots of "weird code" and complication handling in this file is due
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 54 * to these design problems with epoll, as we try very hard to avoid
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 55 * epoll_ctl syscalls for common usage patterns.
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 */ 56 */
31 57
32#include <sys/epoll.h> 58#include <sys/epoll.h>
33 59
34static void 60static void
35epoll_modify (EV_P_ int fd, int oev, int nev) 61epoll_modify (EV_P_ int fd, int oev, int nev)
36{ 62{
37 int mode = nev ? oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL; 63 struct epoll_event ev;
38 64
39 struct epoll_event ev; 65 /*
66 * we handle EPOLL_CTL_DEL by ignoring it here
67 * on the assumption that the fd is gone anyways
68 * if that is wrong, we have to handle the spurious
69 * event in epoll_poll.
70 */
71 if (!nev)
72 return;
73
40 ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */ 74 ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */
41 ev.events =
42 (nev & EV_READ ? EPOLLIN : 0) 75 ev.events = (nev & EV_READ ? EPOLLIN : 0)
43 | (nev & EV_WRITE ? EPOLLOUT : 0); 76 | (nev & EV_WRITE ? EPOLLOUT : 0);
44 77
45 if (epoll_ctl (epoll_fd, mode, fd, &ev)) 78 if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev)))
79 return;
80
81 if (expect_true (errno == ENOENT))
82 {
83 /* on ENOENT the fd went away, so try to do the right thing */
84 if (!nev)
85 return;
86
87 if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev))
88 return;
89 }
90 else if (expect_true (errno == EEXIST))
91 {
92 /* on EEXIST we ignored a previous DEL */
93 if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev))
94 return;
95 }
96
46 fd_kill (EV_A_ fd); 97 fd_kill (EV_A_ fd);
47} 98}
48 99
49static void 100static void
50epoll_poll (EV_P_ ev_tstamp timeout) 101epoll_poll (EV_P_ ev_tstamp timeout)
51{ 102{
52 int eventcnt = epoll_wait (epoll_fd, epoll_events, epoll_eventmax, ceil (timeout * 1000.));
53 int i; 103 int i;
104 int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.));
54 105
55 if (eventcnt < 0) 106 if (expect_false (eventcnt < 0))
107 {
108 if (errno != EINTR)
109 syserr ("(libev) epoll_wait");
110
56 return; 111 return;
112 }
57 113
58 for (i = 0; i < eventcnt; ++i) 114 for (i = 0; i < eventcnt; ++i)
59 fd_event ( 115 {
60 EV_A_ 116 struct epoll_event *ev = epoll_events + i;
61 epoll_events [i].data.u64, 117
118 int fd = ev->data.u64;
62 (epoll_events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) 119 int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
63 | (epoll_events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0) 120 | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0);
64 ); 121 int want = anfds [fd].events;
122
123 if (expect_false (got & ~want))
124 {
125 /* we received an event but are not interested in it, try mod or del */
126 ev->events = (want & EV_READ ? EPOLLIN : 0)
127 | (want & EV_WRITE ? EPOLLOUT : 0);
128
129 epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev);
130 }
131
132 fd_event (EV_A_ fd, got);
133 }
65 134
66 /* if the receive array was full, increase its size */ 135 /* if the receive array was full, increase its size */
67 if (expect_false (eventcnt == epoll_eventmax)) 136 if (expect_false (eventcnt == epoll_eventmax))
68 { 137 {
69 free (epoll_events); 138 ev_free (epoll_events);
70 epoll_eventmax = array_roundsize (epoll_events, epoll_eventmax << 1); 139 epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1);
71 epoll_events = malloc (sizeof (struct epoll_event) * epoll_eventmax); 140 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
72 } 141 }
73} 142}
74 143
75static int 144int inline_size
76epoll_init (EV_P_ int flags) 145epoll_init (EV_P_ int flags)
77{ 146{
78 epoll_fd = epoll_create (256); 147 backend_fd = epoll_create (256);
79 148
80 if (epoll_fd < 0) 149 if (backend_fd < 0)
81 return 0; 150 return 0;
82 151
83 fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); 152 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
84 153
85 method_fudge = 1e-3; /* needed to compensate for epoll returning early */ 154 backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */
86 method_modify = epoll_modify; 155 backend_modify = epoll_modify;
87 method_poll = epoll_poll; 156 backend_poll = epoll_poll;
88 157
89 epoll_eventmax = 64; /* intiial number of events receivable per poll */ 158 epoll_eventmax = 64; /* intiial number of events receivable per poll */
90 epoll_events = malloc (sizeof (struct epoll_event) * epoll_eventmax); 159 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
91 160
92 return EVMETHOD_EPOLL; 161 return EVBACKEND_EPOLL;
93} 162}
94 163
95static void 164void inline_size
96epoll_destroy (EV_P) 165epoll_destroy (EV_P)
97{ 166{
98 close (epoll_fd);
99
100 free (epoll_events); 167 ev_free (epoll_events);
101} 168}
102 169
103static void 170void inline_size
104epoll_fork (EV_P) 171epoll_fork (EV_P)
105{ 172{
106 epoll_fd = epoll_create (256); 173 close (backend_fd);
174
175 while ((backend_fd = epoll_create (256)) < 0)
176 syserr ("(libev) epoll_create");
177
107 fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); 178 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
108 179
109 fd_rearm_all (EV_A); 180 fd_rearm_all (EV_A);
110} 181}
111 182

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