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Comparing libev/ev_epoll.c (file contents):
Revision 1.19 by root, Sun Nov 4 23:14:11 2007 UTC vs.
Revision 1.48 by root, Sat Jul 25 10:14:35 2009 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) 2007,2008,2009 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:
10 * 9 *
11 * * Redistributions of source code must retain the above copyright 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
12 * notice, this list of conditions and the following disclaimer. 14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
13 * 16 *
14 * * Redistributions in binary form must reproduce the above 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
15 * copyright notice, this list of conditions and the following 18 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
16 * disclaimer in the documentation and/or other materials provided 19 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
17 * with the distribution. 20 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
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 21 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 25 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Alternatively, the contents of this file may be used under the terms of
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:
42 *
43 * a) epoll silently removes fds from the fd set. as nothing tells us
44 * that an fd has been removed otherwise, we have to continually
45 * "rearm" fds that we suspect *might* have changed (same
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.
52 *
53 * lots of "weird code" and complication handling in this file is due
54 * to these design problems with epoll, as we try very hard to avoid
55 * epoll_ctl syscalls for common usage patterns and handle the breakage
56 * ensuing from receiving events for closed and otherwise long gone
57 * file descriptors.
30 */ 58 */
31 59
32#include <sys/epoll.h> 60#include <sys/epoll.h>
33 61
34static void 62static void
35epoll_modify (EV_P_ int fd, int oev, int nev) 63epoll_modify (EV_P_ int fd, int oev, int nev)
36{ 64{
37 int mode = nev ? oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL;
38
39 struct epoll_event ev; 65 struct epoll_event ev;
40 ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */ 66 unsigned char oldmask;
41 ev.events = 67
68 /*
69 * we handle EPOLL_CTL_DEL by ignoring it here
70 * on the assumption that the fd is gone anyways
71 * if that is wrong, we have to handle the spurious
72 * event in epoll_poll.
73 * if the fd is added again, we try to ADD it, and, if that
74 * fails, we assume it still has the same eventmask.
75 */
76 if (!nev)
77 return;
78
79 oldmask = anfds [fd].emask;
80 anfds [fd].emask = nev;
81
82 /* store the generation counter in the upper 32 bits, the fd in the lower 32 bits */
83 ev.data.u64 = (uint64_t)(uint32_t)fd
84 | ((uint64_t)(uint32_t)++anfds [fd].egen << 32);
42 (nev & EV_READ ? EPOLLIN : 0) 85 ev.events = (nev & EV_READ ? EPOLLIN : 0)
43 | (nev & EV_WRITE ? EPOLLOUT : 0); 86 | (nev & EV_WRITE ? EPOLLOUT : 0);
44 87
45 if (epoll_ctl (epoll_fd, mode, fd, &ev)) 88 if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev)))
89 return;
90
91 if (expect_true (errno == ENOENT))
92 {
46 if (errno != ENOENT /* on ENOENT the fd went away, so try to do the right thing */ 93 /* if ENOENT then the fd went away, so try to do the right thing */
94 if (!nev)
95 goto dec_egen;
96
47 || (nev && epoll_ctl (epoll_fd, EPOLL_CTL_ADD, fd, &ev))) 97 if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev))
98 return;
99 }
100 else if (expect_true (errno == EEXIST))
101 {
102 /* EEXIST means we ignored a previous DEL, but the fd is still active */
103 /* if the kernel mask is the same as the new mask, we assume it hasn't changed */
104 if (oldmask == nev)
105 goto dec_egen;
106
107 if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev))
108 return;
109 }
110
48 fd_kill (EV_A_ fd); 111 fd_kill (EV_A_ fd);
112
113dec_egen:
114 /* we didn't successfully call epoll_ctl, so decrement the generation counter again */
115 --anfds [fd].egen;
49} 116}
50 117
51static void 118static void
52epoll_poll (EV_P_ ev_tstamp timeout) 119epoll_poll (EV_P_ ev_tstamp timeout)
53{ 120{
54 int eventcnt = epoll_wait (epoll_fd, epoll_events, epoll_eventmax, ceil (timeout * 1000.));
55 int i; 121 int i;
122 int eventcnt;
123
124 /* epoll wait times cannot be larger than (LONG_MAX - 999UL) / HZ msecs, which is below */
125 /* the default libev max wait time, however. */
126 EV_RELEASE_CB;
127 eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.));
128 EV_ACQUIRE_CB;
56 129
57 if (eventcnt < 0) 130 if (expect_false (eventcnt < 0))
131 {
132 if (errno != EINTR)
133 ev_syserr ("(libev) epoll_wait");
134
58 return; 135 return;
136 }
59 137
60 for (i = 0; i < eventcnt; ++i) 138 for (i = 0; i < eventcnt; ++i)
61 fd_event ( 139 {
62 EV_A_ 140 struct epoll_event *ev = epoll_events + i;
63 epoll_events [i].data.u64, 141
142 int fd = (uint32_t)ev->data.u64; /* mask out the lower 32 bits */
143 int want = anfds [fd].events;
64 (epoll_events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) 144 int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
65 | (epoll_events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0) 145 | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0);
66 ); 146
147 /* check for spurious notification */
148 if (expect_false ((uint32_t)anfds [fd].egen != (uint32_t)(ev->data.u64 >> 32)))
149 {
150 /* recreate kernel state */
151 postfork = 1;
152 continue;
153 }
154
155 if (expect_false (got & ~want))
156 {
157 anfds [fd].emask = want;
158
159 /* we received an event but are not interested in it, try mod or del */
160 /* I don't think we ever need MOD, but let's handle it anyways */
161 ev->events = (want & EV_READ ? EPOLLIN : 0)
162 | (want & EV_WRITE ? EPOLLOUT : 0);
163
164 if (epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev))
165 {
166 postfork = 1; /* an error occured, recreate kernel state */
167 continue;
168 }
169 }
170
171 fd_event (EV_A_ fd, got);
172 }
67 173
68 /* if the receive array was full, increase its size */ 174 /* if the receive array was full, increase its size */
69 if (expect_false (eventcnt == epoll_eventmax)) 175 if (expect_false (eventcnt == epoll_eventmax))
70 { 176 {
71 free (epoll_events); 177 ev_free (epoll_events);
72 epoll_eventmax = array_roundsize (epoll_events, epoll_eventmax << 1); 178 epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1);
73 epoll_events = malloc (sizeof (struct epoll_event) * epoll_eventmax); 179 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
74 } 180 }
75} 181}
76 182
77static int 183int inline_size
78epoll_init (EV_P_ int flags) 184epoll_init (EV_P_ int flags)
79{ 185{
186#ifdef EPOLL_CLOEXEC
187 backend_fd = epoll_create1 (EPOLL_CLOEXEC);
188
189 if (backend_fd <= 0)
190#endif
80 epoll_fd = epoll_create (256); 191 backend_fd = epoll_create (256);
81 192
82 if (epoll_fd < 0) 193 if (backend_fd < 0)
83 return 0; 194 return 0;
84 195
85 fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); 196 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
86 197
87 method_fudge = 1e-3; /* needed to compensate for epoll returning early */ 198 backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */
88 method_modify = epoll_modify; 199 backend_modify = epoll_modify;
89 method_poll = epoll_poll; 200 backend_poll = epoll_poll;
90 201
91 epoll_eventmax = 64; /* intiial number of events receivable per poll */ 202 epoll_eventmax = 64; /* initial number of events receivable per poll */
92 epoll_events = malloc (sizeof (struct epoll_event) * epoll_eventmax); 203 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
93 204
94 return EVMETHOD_EPOLL; 205 return EVBACKEND_EPOLL;
95} 206}
96 207
97static void 208void inline_size
98epoll_destroy (EV_P) 209epoll_destroy (EV_P)
99{ 210{
100 close (epoll_fd);
101
102 free (epoll_events); 211 ev_free (epoll_events);
103} 212}
104 213
105static void 214void inline_size
106epoll_fork (EV_P) 215epoll_fork (EV_P)
107{ 216{
108 epoll_fd = epoll_create (256); 217 close (backend_fd);
218
219 while ((backend_fd = epoll_create (256)) < 0)
220 ev_syserr ("(libev) epoll_create");
221
109 fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); 222 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
110 223
111 fd_rearm_all (EV_A); 224 fd_rearm_all (EV_A);
112} 225}
113 226

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