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Comparing libev/ev_epoll.c (file contents):
Revision 1.3 by root, Wed Oct 31 00:24:16 2007 UTC vs.
Revision 1.35 by root, Thu Oct 23 04:56:49 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; 60void inline_size
61unsigned_char_init (unsigned char *base, int count)
62{
63 /* memset might be overkill */
64 while (count--)
65 *base++ = 0;
66}
4 67
5static void 68static void
6epoll_modify (int fd, int oev, int nev) 69epoll_modify (EV_P_ int fd, int oev, int nev)
7{ 70{
8 int mode = nev ? oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL;
9
10 struct epoll_event ev; 71 struct epoll_event ev;
11 ev.data.fd = fd; 72 unsigned char oldmask;
12 ev.events = 73
74 /*
75 * we handle EPOLL_CTL_DEL by ignoring it here
76 * on the assumption that the fd is gone anyways
77 * if that is wrong, we have to handle the spurious
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.
81 */
82 if (!nev)
83 return;
84
85 oldmask = anfds [fd].emask;
86 anfds [fd].emask = nev;
87
88 ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */
13 (nev & EV_READ ? EPOLLIN : 0) 89 ev.events = (nev & EV_READ ? EPOLLIN : 0)
14 | (nev & EV_WRITE ? EPOLLOUT : 0); 90 | (nev & EV_WRITE ? EPOLLOUT : 0);
15 91
16 fprintf (stderr, "reify %d,%d,%d m%d (r=%d)\n", fd, oev, nev, mode,//D 92 if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev)))
17 epoll_ctl (epoll_fd, mode, fd, &ev) 93 return;
18 );//D
19}
20 94
21void epoll_postfork_child (void) 95 if (expect_true (errno == ENOENT))
22{ 96 {
23 int fd; 97 /* if ENOENT then the fd went away, so try to do the right thing */
98 if (!nev)
99 return;
24 100
25 epoll_fd = epoll_create (256); 101 if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev))
26 fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); 102 return;
103 }
104 else if (expect_true (errno == EEXIST))
105 {
106 /* EEXIST means we ignored a previous DEL, but the fd is still active */
107 /* if the kernel mask is the same as the new mask, we assume it hasn't changed */
108 if (oldmask == nev || !epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev))
109 return;
110 }
27 111
28 /* re-register interest in fds */ 112 fd_kill (EV_A_ fd);
29 for (fd = 0; fd < anfdmax; ++fd)
30 if (anfds [fd].wev)
31 epoll_modify (fd, EV_NONE, anfds [fd].wev);
32} 113}
33 114
34static struct epoll_event *events; 115static void
35static int eventmax;
36
37static void epoll_poll (ev_tstamp timeout) 116epoll_poll (EV_P_ ev_tstamp timeout)
38{ 117{
39 int eventcnt = epoll_wait (epoll_fd, events, eventmax, ceil (timeout * 1000.));
40 int i; 118 int i;
119 int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.));
41 120
42 if (eventcnt < 0) 121 if (expect_false (eventcnt < 0))
122 {
123 if (errno != EINTR)
124 syserr ("(libev) epoll_wait");
125
43 return; 126 return;
127 }
44 128
45 for (i = 0; i < eventcnt; ++i) 129 for (i = 0; i < eventcnt; ++i)
46 fd_event ( 130 {
47 events [i].data.fd, 131 struct epoll_event *ev = epoll_events + i;
132
133 int fd = ev->data.u64;
48 (events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) 134 int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
49 | (events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0) 135 | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0);
50 ); 136 int want = anfds [fd].events;
137
138 if (expect_false (got & ~want))
139 {
140 anfds [fd].emask = want;
141
142 /* we received an event but are not interested in it, try mod or del */
143 /* I don't think we ever need MOD, but let's handle it anyways */
144 ev->events = (want & EV_READ ? EPOLLIN : 0)
145 | (want & EV_WRITE ? EPOLLOUT : 0);
146
147 epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev);
148 }
149
150 fd_event (EV_A_ fd, got);
151 }
51 152
52 /* if the receive array was full, increase its size */ 153 /* if the receive array was full, increase its size */
53 if (eventcnt == eventmax) 154 if (expect_false (eventcnt == epoll_eventmax))
54 { 155 {
55 free (events); 156 ev_free (epoll_events);
56 eventmax += eventmax >> 1; 157 epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1);
57 events = malloc (sizeof (struct epoll_event) * eventmax); 158 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
58 } 159 }
59} 160}
60 161
162int inline_size
61void epoll_init (int flags) 163epoll_init (EV_P_ int flags)
62{ 164{
63 epoll_fd = epoll_create (256); 165 backend_fd = epoll_create (256);
64 166
65 if (epoll_fd < 0) 167 if (backend_fd < 0)
66 return; 168 return 0;
67 169
68 fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); 170 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
69 171
70 ev_method = EVMETHOD_EPOLL; 172 backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */
71 method_fudge = 1e-3; /* needed to compensate for epoll returning early */
72 method_modify = epoll_modify; 173 backend_modify = epoll_modify;
73 method_poll = epoll_poll; 174 backend_poll = epoll_poll;
74 175
75 eventmax = 64; /* intiial number of events receivable per poll */ 176 epoll_eventmax = 64; /* intiial number of events receivable per poll */
76 events = malloc (sizeof (struct epoll_event) * eventmax); 177 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
178
179 return EVBACKEND_EPOLL;
77} 180}
181
182void inline_size
183epoll_destroy (EV_P)
184{
185 ev_free (epoll_events);
186}
187
188void inline_size
189epoll_fork (EV_P)
190{
191 close (backend_fd);
192
193 while ((backend_fd = epoll_create (256)) < 0)
194 syserr ("(libev) epoll_create");
195
196 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
197
198 fd_rearm_all (EV_A);
199}
200

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