ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/libev/ev_epoll.c
(Generate patch)

Comparing libev/ev_epoll.c (file contents):
Revision 1.32 by root, Thu Dec 13 16:52:50 2007 UTC vs.
Revision 1.45 by root, Fri Jul 10 00:36:21 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 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.
30 */ 38 */
31 39
32/* 40/*
33 * general notes about epoll: 41 * general notes about epoll:
34 * 42 *
… …
42 * limits the applicability over poll, so this is not a generic 50 * limits the applicability over poll, so this is not a generic
43 * poll replacement. 51 * poll replacement.
44 * 52 *
45 * lots of "weird code" and complication handling in this file is due 53 * lots of "weird code" and complication handling in this file is due
46 * to these design problems with epoll, as we try very hard to avoid 54 * to these design problems with epoll, as we try very hard to avoid
47 * epoll_ctl syscalls for common usage patterns. 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.
48 */ 58 */
49 59
50#include <sys/epoll.h> 60#include <sys/epoll.h>
51 61
52static void 62static void
53epoll_modify (EV_P_ int fd, int oev, int nev) 63epoll_modify (EV_P_ int fd, int oev, int nev)
54{ 64{
55 struct epoll_event ev; 65 struct epoll_event ev;
66 unsigned char oldmask;
56 67
57 /* 68 /*
58 * we handle EPOLL_CTL_DEL by ignoring it here 69 * we handle EPOLL_CTL_DEL by ignoring it here
59 * on the assumption that the fd is gone anyways 70 * on the assumption that the fd is gone anyways
60 * if that is wrong, we have to handle the spurious 71 * if that is wrong, we have to handle the spurious
61 * event in epoll_poll. 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.
62 */ 75 */
63 if (!nev) 76 if (!nev)
64 return; 77 return;
65 78
66 ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */ 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);
67 ev.events = (nev & EV_READ ? EPOLLIN : 0) 85 ev.events = (nev & EV_READ ? EPOLLIN : 0)
68 | (nev & EV_WRITE ? EPOLLOUT : 0); 86 | (nev & EV_WRITE ? EPOLLOUT : 0);
69 87
70 if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev))) 88 if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev)))
71 return; 89 return;
72 90
73 if (expect_true (errno == ENOENT)) 91 if (expect_true (errno == ENOENT))
74 { 92 {
75 /* 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 */
76 if (!nev) 94 if (!nev)
77 return; 95 goto dec_egen;
78 96
79 if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)) 97 if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev))
80 return; 98 return;
81 } 99 }
82 else if (expect_true (errno == EEXIST)) 100 else if (expect_true (errno == EEXIST))
83 { 101 {
84 /* on EEXIST we ignored a previous DEL */ 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
85 if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev)) 107 if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev))
86 return; 108 return;
87 } 109 }
88 110
89 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;
90} 116}
91 117
92static void 118static void
93epoll_poll (EV_P_ ev_tstamp timeout) 119epoll_poll (EV_P_ ev_tstamp timeout)
94{ 120{
95 int i; 121 int i;
122 int eventcnt;
123
124 EV_SUSPEND_CB;
96 int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.)); 125 eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.));
126 EV_RESUME_CB;
97 127
98 if (expect_false (eventcnt < 0)) 128 if (expect_false (eventcnt < 0))
99 { 129 {
100 if (errno != EINTR) 130 if (errno != EINTR)
101 syserr ("(libev) epoll_wait"); 131 ev_syserr ("(libev) epoll_wait");
102 132
103 return; 133 return;
104 } 134 }
105 135
106 for (i = 0; i < eventcnt; ++i) 136 for (i = 0; i < eventcnt; ++i)
107 { 137 {
108 struct epoll_event *ev = epoll_events + i; 138 struct epoll_event *ev = epoll_events + i;
109 139
110 int fd = ev->data.u64; 140 int fd = (uint32_t)ev->data.u64; /* mask out the lower 32 bits */
141 int want = anfds [fd].events;
111 int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) 142 int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
112 | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0); 143 | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0);
113 int want = anfds [fd].events; 144
145 /* check for spurious notification */
146 if (expect_false ((uint32_t)anfds [fd].egen != (uint32_t)(ev->data.u64 >> 32)))
147 {
148 /* recreate kernel state */
149 postfork = 1;
150 continue;
151 }
114 152
115 if (expect_false (got & ~want)) 153 if (expect_false (got & ~want))
116 { 154 {
155 anfds [fd].emask = want;
156
117 /* we received an event but are not interested in it, try mod or del */ 157 /* we received an event but are not interested in it, try mod or del */
158 /* I don't think we ever need MOD, but let's handle it anyways */
118 ev->events = (want & EV_READ ? EPOLLIN : 0) 159 ev->events = (want & EV_READ ? EPOLLIN : 0)
119 | (want & EV_WRITE ? EPOLLOUT : 0); 160 | (want & EV_WRITE ? EPOLLOUT : 0);
120 161
121 epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev); 162 if (epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev))
163 {
164 postfork = 1; /* an error occured, recreate kernel state */
165 continue;
166 }
122 } 167 }
123 168
124 fd_event (EV_A_ fd, got); 169 fd_event (EV_A_ fd, got);
125 } 170 }
126 171
… …
145 190
146 backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */ 191 backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */
147 backend_modify = epoll_modify; 192 backend_modify = epoll_modify;
148 backend_poll = epoll_poll; 193 backend_poll = epoll_poll;
149 194
150 epoll_eventmax = 64; /* intiial number of events receivable per poll */ 195 epoll_eventmax = 64; /* initial number of events receivable per poll */
151 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); 196 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
152 197
153 return EVBACKEND_EPOLL; 198 return EVBACKEND_EPOLL;
154} 199}
155 200
… …
163epoll_fork (EV_P) 208epoll_fork (EV_P)
164{ 209{
165 close (backend_fd); 210 close (backend_fd);
166 211
167 while ((backend_fd = epoll_create (256)) < 0) 212 while ((backend_fd = epoll_create (256)) < 0)
168 syserr ("(libev) epoll_create"); 213 ev_syserr ("(libev) epoll_create");
169 214
170 fcntl (backend_fd, F_SETFD, FD_CLOEXEC); 215 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
171 216
172 fd_rearm_all (EV_A); 217 fd_rearm_all (EV_A);
173} 218}

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines