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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 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 |
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8 | * modification, are permitted provided that the following conditions are |
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9 | * met: |
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10 | * |
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11 | * * Redistributions of source code must retain the above copyright |
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12 | * notice, this list of conditions and the following disclaimer. |
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13 | * |
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14 | * * Redistributions in binary form must reproduce the above |
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15 | * copyright notice, this list of conditions and the following |
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16 | * disclaimer in the documentation and/or other materials provided |
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17 | * with the distribution. |
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18 | * |
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19 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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20 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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21 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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22 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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23 | * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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24 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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25 | * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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26 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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27 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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28 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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29 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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30 | */ |
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31 | |
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32 | /* |
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33 | * general notes about epoll: |
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34 | * |
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35 | * a) epoll silently removes fds from the fd set. as nothing tells us |
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36 | * that an fd has been removed otherwise, we have to continually |
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37 | * "rearm" fds that we suspect *might* have changed (same |
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38 | * problem with kqueue, but much less costly there). |
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39 | * b) the fact that ADD != MOD creates a lot of extra syscalls due to a) |
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40 | * and seems not to have any advantage. |
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41 | * c) the inability to handle fork or file descriptors (think dup) |
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42 | * limits the applicability over poll, so this is not a generic |
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43 | * poll replacement. |
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44 | * |
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45 | * lots of "weird code" and complication handling in this file is due |
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46 | * to these design problems with epoll, as we try very hard to avoid |
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47 | * epoll_ctl syscalls for common usage patterns. |
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48 | */ |
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49 | |
1 | #include <sys/epoll.h> |
50 | #include <sys/epoll.h> |
2 | |
51 | |
3 | static int epoll_fd = -1; |
52 | static void |
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53 | epoll_modify (EV_P_ int fd, int oev, int nev) |
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54 | { |
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55 | struct epoll_event ev; |
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56 | |
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57 | /* |
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58 | * we handle EPOLL_CTL_DEL by ignoring it here |
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59 | * on the assumption that the fd is gone anyways |
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60 | * if that is wrong, we have to handle the spurious |
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61 | * event in epoll_poll. |
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62 | */ |
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63 | if (!nev) |
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64 | return; |
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65 | |
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66 | ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */ |
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67 | ev.events = (nev & EV_READ ? EPOLLIN : 0) |
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68 | | (nev & EV_WRITE ? EPOLLOUT : 0); |
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69 | |
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70 | if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev))) |
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71 | return; |
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72 | |
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73 | if (expect_true (errno == ENOENT)) |
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74 | { |
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75 | /* on ENOENT the fd went away, so try to do the right thing */ |
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76 | if (!nev) |
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77 | return; |
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78 | |
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79 | if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)) |
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80 | return; |
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81 | } |
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82 | else if (expect_true (errno == EEXIST)) |
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83 | { |
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84 | /* on EEXIST we ignored a previous DEL */ |
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85 | if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev)) |
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86 | return; |
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87 | } |
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88 | |
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89 | fd_kill (EV_A_ fd); |
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90 | } |
4 | |
91 | |
5 | static void |
92 | static void |
6 | epoll_modify (int fd, int oev, int nev) |
93 | epoll_poll (EV_P_ ev_tstamp timeout) |
7 | { |
94 | { |
8 | int mode = nev ? oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL; |
95 | int i; |
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96 | int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.)); |
9 | |
97 | |
10 | struct epoll_event ev; |
98 | if (expect_false (eventcnt < 0)) |
11 | ev.data.fd = fd; |
99 | { |
12 | ev.events = |
100 | if (errno != EINTR) |
13 | (nev & EV_READ ? EPOLLIN : 0) |
101 | syserr ("(libev) epoll_wait"); |
14 | | (nev & EV_WRITE ? EPOLLOUT : 0); |
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15 | |
102 | |
16 | fprintf (stderr, "reify %d,%d,%d m%d (r=%d)\n", fd, oev, nev, mode,//D |
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17 | epoll_ctl (epoll_fd, mode, fd, &ev) |
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18 | );//D |
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19 | } |
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20 | |
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21 | void epoll_postfork_child (void) |
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22 | { |
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23 | int fd; |
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24 | |
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25 | epoll_fd = epoll_create (256); |
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26 | |
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27 | /* re-register interest in fds */ |
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28 | for (fd = 0; fd < anfdmax; ++fd) |
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29 | if (anfds [fd].wev) |
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30 | epoll_modify (fd, EV_NONE, anfds [fd].wev); |
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31 | } |
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32 | |
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33 | static struct epoll_event *events; |
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34 | static int eventmax; |
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35 | |
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36 | static void epoll_poll (ev_tstamp timeout) |
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37 | { |
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38 | int eventcnt = epoll_wait (epoll_fd, events, eventmax, ceil (timeout * 1000.)); |
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39 | int i; |
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40 | |
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41 | if (eventcnt < 0) |
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42 | return; |
103 | return; |
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104 | } |
43 | |
105 | |
44 | for (i = 0; i < eventcnt; ++i) |
106 | for (i = 0; i < eventcnt; ++i) |
45 | fd_event ( |
107 | { |
46 | events [i].data.fd, |
108 | struct epoll_event *ev = epoll_events + i; |
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109 | |
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110 | int fd = ev->data.u64; |
47 | (events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) |
111 | int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) |
48 | | (events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0) |
112 | | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0); |
49 | ); |
113 | int want = anfds [fd].events; |
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114 | |
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115 | if (expect_false (got & ~want)) |
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116 | { |
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117 | /* we received an event but are not interested in it, try mod or del */ |
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118 | ev->events = (want & EV_READ ? EPOLLIN : 0) |
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119 | | (want & EV_WRITE ? EPOLLOUT : 0); |
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120 | |
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121 | epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev); |
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122 | } |
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123 | |
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124 | fd_event (EV_A_ fd, got); |
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125 | } |
50 | |
126 | |
51 | /* if the receive array was full, increase its size */ |
127 | /* if the receive array was full, increase its size */ |
52 | if (eventcnt == eventmax) |
128 | if (expect_false (eventcnt == epoll_eventmax)) |
53 | { |
129 | { |
54 | free (events); |
130 | ev_free (epoll_events); |
55 | eventmax += eventmax >> 1; |
131 | epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1); |
56 | events = malloc (sizeof (struct epoll_event) * eventmax); |
132 | epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); |
57 | } |
133 | } |
58 | } |
134 | } |
59 | |
135 | |
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136 | int inline_size |
60 | int epoll_init (int flags) |
137 | epoll_init (EV_P_ int flags) |
61 | { |
138 | { |
62 | epoll_fd = epoll_create (256); |
139 | backend_fd = epoll_create (256); |
63 | |
140 | |
64 | if (epoll_fd < 0) |
141 | if (backend_fd < 0) |
65 | return 0; |
142 | return 0; |
66 | |
143 | |
67 | ev_method = EVMETHOD_EPOLL; |
144 | fcntl (backend_fd, F_SETFD, FD_CLOEXEC); |
68 | method_fudge = 1e-3; /* needed to compensate for epoll returning early */ |
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69 | method_modify = epoll_modify; |
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70 | method_poll = epoll_poll; |
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71 | |
145 | |
72 | eventmax = 64; /* intiial number of events receivable per poll */ |
146 | backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */ |
73 | events = malloc (sizeof (struct epoll_event) * eventmax); |
147 | backend_modify = epoll_modify; |
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148 | backend_poll = epoll_poll; |
74 | |
149 | |
75 | return 1; |
150 | epoll_eventmax = 64; /* intiial number of events receivable per poll */ |
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151 | epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); |
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152 | |
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153 | return EVBACKEND_EPOLL; |
76 | } |
154 | } |
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155 | |
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156 | void inline_size |
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157 | epoll_destroy (EV_P) |
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158 | { |
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159 | ev_free (epoll_events); |
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160 | } |
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161 | |
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162 | void inline_size |
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163 | epoll_fork (EV_P) |
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164 | { |
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165 | close (backend_fd); |
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166 | |
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167 | while ((backend_fd = epoll_create (256)) < 0) |
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168 | syserr ("(libev) epoll_create"); |
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169 | |
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170 | fcntl (backend_fd, F_SETFD, FD_CLOEXEC); |
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171 | |
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172 | fd_rearm_all (EV_A); |
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173 | } |
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174 | |