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Comparing libev/ev_epoll.c (file contents):
Revision 1.1 by root, Tue Oct 30 20:59:31 2007 UTC vs.
Revision 1.34 by root, Fri May 23 16:37:38 2008 UTC

1/*
2 * libev epoll fd activity backend
3 *
4 * Copyright (c) 2007,2008 Marc Alexander Lehmann <libev@schmorp.de>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without modifica-
8 * tion, are permitted provided that the following conditions are 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.
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.
56 */
57
1#include <sys/epoll.h> 58#include <sys/epoll.h>
2 59
3static int epoll_fd = -1; 60static void
61epoll_modify (EV_P_ int fd, int oev, int nev)
62{
63 struct epoll_event ev;
64
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
74 ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */
75 ev.events = (nev & EV_READ ? EPOLLIN : 0)
76 | (nev & EV_WRITE ? EPOLLOUT : 0);
77
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
97 fd_kill (EV_A_ fd);
98}
4 99
5static void 100static void
6epoll_reify_fd (int fd) 101epoll_poll (EV_P_ ev_tstamp timeout)
7{ 102{
8 ANFD *anfd = anfds + fd; 103 int i;
9 struct ev_io *w; 104 int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.));
10 105
11 int wev = 0; 106 if (expect_false (eventcnt < 0))
107 {
108 if (errno != EINTR)
109 syserr ("(libev) epoll_wait");
12 110
13 for (w = anfd->head; w; w = w->next) 111 return;
14 wev |= w->events; 112 }
15 113
16 if (anfd->wev != wev) 114 for (i = 0; i < eventcnt; ++i)
17 { 115 {
18 int mode = wev ? anfd->wev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL; 116 struct epoll_event *ev = epoll_events + i;
19 struct epoll_event ev; 117
20 ev.events = wev; 118 int fd = ev->data.u64;
21 ev.data.fd = fd; 119 int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
22 fprintf (stderr, "reify %d,%d,%d m%d (r=%d)\n", fd, anfd->wev, wev, mode,//D 120 | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0);
23 epoll_ctl (epoll_fd, mode, fd, &ev) 121 int want = anfds [fd].events;
24 );//D 122
25 anfd->wev = wev; 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 }
134
135 /* if the receive array was full, increase its size */
136 if (expect_false (eventcnt == epoll_eventmax))
137 {
138 ev_free (epoll_events);
139 epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1);
140 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
26 } 141 }
27} 142}
28 143
29void epoll_postfork_child (void) 144int inline_size
145epoll_init (EV_P_ int flags)
30{ 146{
31 int i; 147 backend_fd = epoll_create (256);
32 148
33 epoll_fd = epoll_create (256); 149 if (backend_fd < 0)
150 return 0;
34 151
35 for (i = 0; i < anfdmax; ++i) 152 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
36 epoll_reify_fd (i); 153
154 backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */
155 backend_modify = epoll_modify;
156 backend_poll = epoll_poll;
157
158 epoll_eventmax = 64; /* intiial number of events receivable per poll */
159 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
160
161 return EVBACKEND_EPOLL;
37} 162}
38 163
39static void epoll_reify (void) 164void inline_size
165epoll_destroy (EV_P)
40{ 166{
41 int i; 167 ev_free (epoll_events);
42 for (i = 0; i < fdchangecnt; ++i)
43 epoll_reify_fd (fdchanges [i]);
44} 168}
45 169
46static struct epoll_event *events; 170void inline_size
47static int eventmax; 171epoll_fork (EV_P)
172{
173 close (backend_fd);
48 174
49static void epoll_poll (ev_tstamp timeout) 175 while ((backend_fd = epoll_create (256)) < 0)
50{ 176 syserr ("(libev) epoll_create");
51 int eventcnt = epoll_wait (epoll_fd, events, eventmax, ceil (timeout * 1000.));
52 int i;
53 177
54 if (eventcnt < 0) 178 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
55 return;
56 179
57 for (i = 0; i < eventcnt; ++i) 180 fd_rearm_all (EV_A);
58 fd_event (
59 events [i].data.fd,
60 (events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLPRI) ? EV_WRITE : 0)
61 | (events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0)
62 );
63
64 /* if the receive array was full, increase its size */
65 if (eventcnt == eventmax)
66 {
67 free (events);
68 eventmax += eventmax >> 1;
69 events = malloc (sizeof (struct epoll_event) * eventmax);
70 }
71} 181}
72 182
73int epoll_init (int flags)
74{
75 epoll_fd = epoll_create (256);
76
77 if (epoll_fd < 0)
78 return 0;
79
80 ev_method = EVMETHOD_EPOLL;
81 method_fudge = 1e-3; /* needed to compensate fro epoll returning early */
82 method_reify = epoll_reify;
83 method_poll = epoll_poll;
84
85 eventmax = 64; /* intiial number of events receivable per poll */
86 events = malloc (sizeof (struct epoll_event) * eventmax);
87
88 return 1;
89}

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