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Comparing libev/ev_epoll.c (file contents):
Revision 1.32 by root, Thu Dec 13 16:52:50 2007 UTC vs.
Revision 1.36 by root, Mon Oct 27 11:08:29 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:
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 *
… …
47 * epoll_ctl syscalls for common usage patterns. 55 * epoll_ctl syscalls for common usage patterns.
48 */ 56 */
49 57
50#include <sys/epoll.h> 58#include <sys/epoll.h>
51 59
60void inline_size
61unsigned_char_init (unsigned char *base, int count)
62{
63 /* memset might be overkill */
64 while (count--)
65 *base++ = 0;
66}
67
52static void 68static void
53epoll_modify (EV_P_ int fd, int oev, int nev) 69epoll_modify (EV_P_ int fd, int oev, int nev)
54{ 70{
55 struct epoll_event ev; 71 struct epoll_event ev;
72 unsigned char oldmask;
56 73
57 /* 74 /*
58 * we handle EPOLL_CTL_DEL by ignoring it here 75 * we handle EPOLL_CTL_DEL by ignoring it here
59 * on the assumption that the fd is gone anyways 76 * on the assumption that the fd is gone anyways
60 * if that is wrong, we have to handle the spurious 77 * if that is wrong, we have to handle the spurious
61 * event in epoll_poll. 78 * event in epoll_poll.
79 * the fd is later added, we try to ADD it, and, if that
80 * fails, we assume it still has the same eventmask.
62 */ 81 */
63 if (!nev) 82 if (!nev)
64 return; 83 return;
65 84
66 ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */ 85 oldmask = anfds [fd].emask;
86 anfds [fd].emask = nev;
87
88 /* store the generation counter in the upper 32 bits */
89 ev.data.u64 = fd | ((uint64_t)++anfds [fd].egen << 32);
67 ev.events = (nev & EV_READ ? EPOLLIN : 0) 90 ev.events = (nev & EV_READ ? EPOLLIN : 0)
68 | (nev & EV_WRITE ? EPOLLOUT : 0); 91 | (nev & EV_WRITE ? EPOLLOUT : 0);
69 92
70 if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev))) 93 if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev)))
71 return; 94 return;
72 95
73 if (expect_true (errno == ENOENT)) 96 if (expect_true (errno == ENOENT))
74 { 97 {
75 /* on ENOENT the fd went away, so try to do the right thing */ 98 /* if ENOENT then the fd went away, so try to do the right thing */
76 if (!nev) 99 if (!nev)
77 return; 100 goto dec_egen;
78 101
79 if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)) 102 if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev))
80 return; 103 return;
81 } 104 }
82 else if (expect_true (errno == EEXIST)) 105 else if (expect_true (errno == EEXIST))
83 { 106 {
84 /* on EEXIST we ignored a previous DEL */ 107 /* EEXIST means we ignored a previous DEL, but the fd is still active */
108 /* if the kernel mask is the same as the new mask, we assume it hasn't changed */
109 if (oldmask == nev)
110 goto dec_egen;
111
85 if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev)) 112 if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev))
86 return; 113 return;
87 } 114 }
88 115
89 fd_kill (EV_A_ fd); 116 fd_kill (EV_A_ fd);
117
118dec_egen:
119 /* we didn't successfully call epoll_ctl, so decrement the generation counter again */
120 --anfds [fd].egen;
90} 121}
91 122
92static void 123static void
93epoll_poll (EV_P_ ev_tstamp timeout) 124epoll_poll (EV_P_ ev_tstamp timeout)
94{ 125{
… …
105 136
106 for (i = 0; i < eventcnt; ++i) 137 for (i = 0; i < eventcnt; ++i)
107 { 138 {
108 struct epoll_event *ev = epoll_events + i; 139 struct epoll_event *ev = epoll_events + i;
109 140
110 int fd = ev->data.u64; 141 int fd = (uint32_t)ev->data.u64; /* mask out the lower 32 bits */
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 int want = anfds [fd].events;
114 145
146 if (anfds [fd].egen != (unsigned char)(ev->data.u64 >> 32))
147 /*fprintf (stderr, "spurious notification fd %d, %d vs %d\n", fd, (int)(ev->data.u64 >> 32), anfds [fd].egen);*/
148 continue;
149
115 if (expect_false (got & ~want)) 150 if (expect_false (got & ~want))
116 { 151 {
152 anfds [fd].emask = want;
153
117 /* we received an event but are not interested in it, try mod or del */ 154 /* we received an event but are not interested in it, try mod or del */
155 /* I don't think we ever need MOD, but let's handle it anyways */
118 ev->events = (want & EV_READ ? EPOLLIN : 0) 156 ev->events = (want & EV_READ ? EPOLLIN : 0)
119 | (want & EV_WRITE ? EPOLLOUT : 0); 157 | (want & EV_WRITE ? EPOLLOUT : 0);
120 158
121 epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev); 159 epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev);
122 } 160 }

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