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1 | /* |
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2 | * libev epoll fd activity backend |
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3 | * |
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4 | * Copyright (c) 2007,2008 Marc Alexander Lehmann <libev@schmorp.de> |
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5 | * All rights reserved. |
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6 | * |
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7 | * Redistribution and use in source and binary forms, with or without modifica- |
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8 | * tion, are permitted provided that the following conditions are met: |
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9 | * |
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10 | * 1. Redistributions of source code must retain the above copyright notice, |
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11 | * this list of conditions and the following disclaimer. |
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12 | * |
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13 | * 2. Redistributions in binary form must reproduce the above copyright |
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14 | * notice, this list of conditions and the following disclaimer in the |
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15 | * documentation and/or other materials provided with the distribution. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
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18 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- |
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19 | * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
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20 | * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- |
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21 | * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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22 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
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23 | * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
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24 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH- |
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25 | * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
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26 | * OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | * |
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28 | * Alternatively, the contents of this file may be used under the terms of |
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29 | * the GNU General Public License ("GPL") version 2 or any later version, |
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30 | * in which case the provisions of the GPL are applicable instead of |
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31 | * the above. If you wish to allow the use of your version of this file |
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32 | * only under the terms of the GPL and not to allow others to use your |
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33 | * version of this file under the BSD license, indicate your decision |
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34 | * by deleting the provisions above and replace them with the notice |
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35 | * and other provisions required by the GPL. If you do not delete the |
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36 | * provisions above, a recipient may use your version of this file under |
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37 | * either the BSD or the GPL. |
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38 | */ |
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39 | |
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40 | /* |
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41 | * general notes about epoll: |
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42 | * |
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43 | * a) epoll silently removes fds from the fd set. as nothing tells us |
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44 | * that an fd has been removed otherwise, we have to continually |
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45 | * "rearm" fds that we suspect *might* have changed (same |
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46 | * problem with kqueue, but much less costly there). |
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47 | * b) the fact that ADD != MOD creates a lot of extra syscalls due to a) |
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48 | * and seems not to have any advantage. |
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49 | * c) the inability to handle fork or file descriptors (think dup) |
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50 | * limits the applicability over poll, so this is not a generic |
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51 | * poll replacement. |
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52 | * |
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53 | * lots of "weird code" and complication handling in this file is due |
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54 | * to these design problems with epoll, as we try very hard to avoid |
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55 | * epoll_ctl syscalls for common usage patterns. |
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56 | */ |
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57 | |
1 | #include <sys/epoll.h> |
58 | #include <sys/epoll.h> |
2 | |
59 | |
3 | static int epoll_fd = -1; |
60 | void inline_size |
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61 | unsigned_char_init (unsigned char *base, int count) |
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62 | { |
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63 | /* memset might be overkill */ |
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64 | while (count--) |
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65 | *base++ = 0; |
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66 | } |
4 | |
67 | |
5 | static void |
68 | static void |
6 | epoll_modify (int fd, int oev, int nev) |
69 | epoll_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; |
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9 | |
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10 | struct epoll_event ev; |
71 | struct epoll_event ev; |
11 | ev.data.fd = fd; |
72 | unsigned char oldmask; |
12 | ev.events = |
73 | |
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74 | /* |
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75 | * we handle EPOLL_CTL_DEL by ignoring it here |
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76 | * on the assumption that the fd is gone anyways |
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77 | * if that is wrong, we have to handle the spurious |
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78 | * event in epoll_poll. |
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79 | * the fd is later added, we try to ADD it, and, if that |
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80 | * fails, we assume it still has the same eventmask. |
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81 | */ |
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82 | if (!nev) |
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83 | return; |
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84 | |
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85 | oldmask = anfds [fd].emask; |
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86 | anfds [fd].emask = nev; |
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87 | |
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88 | /* store the generation counter in the upper 32 bits */ |
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89 | ev.data.u64 = fd | ((uint64_t)++anfds [fd].egen << 32); |
13 | (nev & EV_READ ? EPOLLIN : 0) |
90 | ev.events = (nev & EV_READ ? EPOLLIN : 0) |
14 | | (nev & EV_WRITE ? EPOLLOUT : 0); |
91 | | (nev & EV_WRITE ? EPOLLOUT : 0); |
15 | |
92 | |
16 | fprintf (stderr, "reify %d,%d,%d m%d (r=%d)\n", fd, oev, nev, mode,//D |
93 | if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev))) |
17 | epoll_ctl (epoll_fd, mode, fd, &ev) |
94 | return; |
18 | );//D |
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19 | } |
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20 | |
95 | |
21 | void epoll_postfork_child (void) |
96 | if (expect_true (errno == ENOENT)) |
22 | { |
97 | { |
23 | int fd; |
98 | /* if ENOENT then the fd went away, so try to do the right thing */ |
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99 | if (!nev) |
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100 | goto dec_egen; |
24 | |
101 | |
25 | epoll_fd = epoll_create (256); |
102 | if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)) |
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103 | return; |
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104 | } |
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105 | else if (expect_true (errno == EEXIST)) |
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106 | { |
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107 | /* EEXIST means we ignored a previous DEL, but the fd is still active */ |
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108 | /* if the kernel mask is the same as the new mask, we assume it hasn't changed */ |
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109 | if (oldmask == nev) |
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110 | goto dec_egen; |
26 | |
111 | |
27 | /* re-register interest in fds */ |
112 | if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev)) |
28 | for (fd = 0; fd < anfdmax; ++fd) |
113 | return; |
29 | if (anfds [fd].wev) |
114 | } |
30 | epoll_modify (fd, EV_NONE, anfds [fd].wev); |
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31 | } |
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32 | |
115 | |
33 | static struct epoll_event *events; |
116 | fd_kill (EV_A_ fd); |
34 | static int eventmax; |
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35 | |
117 | |
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118 | dec_egen: |
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119 | /* we didn't successfully call epoll_ctl, so decrement the generation counter again */ |
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120 | --anfds [fd].egen; |
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121 | } |
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122 | |
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123 | static void |
36 | static void epoll_poll (ev_tstamp timeout) |
124 | epoll_poll (EV_P_ ev_tstamp timeout) |
37 | { |
125 | { |
38 | int eventcnt = epoll_wait (epoll_fd, events, eventmax, ceil (timeout * 1000.)); |
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39 | int i; |
126 | int i; |
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127 | int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.)); |
40 | |
128 | |
41 | if (eventcnt < 0) |
129 | if (expect_false (eventcnt < 0)) |
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130 | { |
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131 | if (errno != EINTR) |
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132 | syserr ("(libev) epoll_wait"); |
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133 | |
42 | return; |
134 | return; |
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135 | } |
43 | |
136 | |
44 | for (i = 0; i < eventcnt; ++i) |
137 | for (i = 0; i < eventcnt; ++i) |
45 | fd_event ( |
138 | { |
46 | events [i].data.fd, |
139 | struct epoll_event *ev = epoll_events + i; |
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140 | |
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141 | int fd = (uint32_t)ev->data.u64; /* mask out the lower 32 bits */ |
47 | (events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) |
142 | int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) |
48 | | (events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0) |
143 | | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0); |
49 | ); |
144 | int want = anfds [fd].events; |
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145 | |
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146 | if (anfds [fd].egen != (unsigned char)(ev->data.u64 >> 32)) |
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147 | /*fprintf (stderr, "spurious notification fd %d, %d vs %d\n", fd, (int)(ev->data.u64 >> 32), anfds [fd].egen);*/ |
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148 | continue; |
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149 | |
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150 | if (expect_false (got & ~want)) |
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151 | { |
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152 | anfds [fd].emask = want; |
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153 | |
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154 | /* we received an event but are not interested in it, try mod or del */ |
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155 | /* I don't think we ever need MOD, but let's handle it anyways */ |
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156 | ev->events = (want & EV_READ ? EPOLLIN : 0) |
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157 | | (want & EV_WRITE ? EPOLLOUT : 0); |
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158 | |
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159 | epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev); |
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160 | } |
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161 | |
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162 | fd_event (EV_A_ fd, got); |
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163 | } |
50 | |
164 | |
51 | /* if the receive array was full, increase its size */ |
165 | /* if the receive array was full, increase its size */ |
52 | if (eventcnt == eventmax) |
166 | if (expect_false (eventcnt == epoll_eventmax)) |
53 | { |
167 | { |
54 | free (events); |
168 | ev_free (epoll_events); |
55 | eventmax += eventmax >> 1; |
169 | epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1); |
56 | events = malloc (sizeof (struct epoll_event) * eventmax); |
170 | epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); |
57 | } |
171 | } |
58 | } |
172 | } |
59 | |
173 | |
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174 | int inline_size |
60 | int epoll_init (int flags) |
175 | epoll_init (EV_P_ int flags) |
61 | { |
176 | { |
62 | epoll_fd = epoll_create (256); |
177 | backend_fd = epoll_create (256); |
63 | |
178 | |
64 | if (epoll_fd < 0) |
179 | if (backend_fd < 0) |
65 | return 0; |
180 | return 0; |
66 | |
181 | |
67 | ev_method = EVMETHOD_EPOLL; |
182 | fcntl (backend_fd, F_SETFD, FD_CLOEXEC); |
68 | method_fudge = 1e-3; /* needed to compensate for epoll returning early */ |
183 | |
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184 | backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */ |
69 | method_modify = epoll_modify; |
185 | backend_modify = epoll_modify; |
70 | method_poll = epoll_poll; |
186 | backend_poll = epoll_poll; |
71 | |
187 | |
72 | eventmax = 64; /* intiial number of events receivable per poll */ |
188 | epoll_eventmax = 64; /* intiial number of events receivable per poll */ |
73 | events = malloc (sizeof (struct epoll_event) * eventmax); |
189 | epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); |
74 | |
190 | |
75 | return 1; |
191 | return EVBACKEND_EPOLL; |
76 | } |
192 | } |
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193 | |
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194 | void inline_size |
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195 | epoll_destroy (EV_P) |
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196 | { |
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197 | ev_free (epoll_events); |
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198 | } |
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199 | |
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200 | void inline_size |
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201 | epoll_fork (EV_P) |
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202 | { |
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203 | close (backend_fd); |
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204 | |
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205 | while ((backend_fd = epoll_create (256)) < 0) |
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206 | syserr ("(libev) epoll_create"); |
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207 | |
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208 | fcntl (backend_fd, F_SETFD, FD_CLOEXEC); |
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209 | |
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210 | fd_rearm_all (EV_A); |
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211 | } |
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212 | |