| 1 |
root |
1.5 |
/* |
| 2 |
root |
1.9 |
* libev epoll fd activity backend |
| 3 |
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* |
| 4 |
root |
1.73 |
* Copyright (c) 2007,2008,2009,2010,2011,2016,2017,2019 Marc Alexander Lehmann <libev@schmorp.de> |
| 5 |
root |
1.5 |
* All rights reserved. |
| 6 |
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* |
| 7 |
root |
1.33 |
* Redistribution and use in source and binary forms, with or without modifica- |
| 8 |
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* tion, are permitted provided that the following conditions are met: |
| 9 |
root |
1.60 |
* |
| 10 |
root |
1.33 |
* 1. Redistributions of source code must retain the above copyright notice, |
| 11 |
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* this list of conditions and the following disclaimer. |
| 12 |
root |
1.60 |
* |
| 13 |
root |
1.33 |
* 2. Redistributions in binary form must reproduce the above copyright |
| 14 |
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* notice, this list of conditions and the following disclaimer in the |
| 15 |
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* documentation and/or other materials provided with the distribution. |
| 16 |
root |
1.60 |
* |
| 17 |
root |
1.33 |
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 18 |
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- |
| 19 |
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* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
| 20 |
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- |
| 21 |
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* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| 22 |
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH- |
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* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
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* OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 |
root |
1.5 |
* |
| 28 |
root |
1.33 |
* Alternatively, the contents of this file may be used under the terms of |
| 29 |
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* the GNU General Public License ("GPL") version 2 or any later version, |
| 30 |
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* in which case the provisions of the GPL are applicable instead of |
| 31 |
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* the above. If you wish to allow the use of your version of this file |
| 32 |
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* only under the terms of the GPL and not to allow others to use your |
| 33 |
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* version of this file under the BSD license, indicate your decision |
| 34 |
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* by deleting the provisions above and replace them with the notice |
| 35 |
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* and other provisions required by the GPL. If you do not delete the |
| 36 |
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* provisions above, a recipient may use your version of this file under |
| 37 |
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* either the BSD or the GPL. |
| 38 |
root |
1.5 |
*/ |
| 39 |
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| 40 |
root |
1.32 |
/* |
| 41 |
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* general notes about epoll: |
| 42 |
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* |
| 43 |
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* a) epoll silently removes fds from the fd set. as nothing tells us |
| 44 |
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* that an fd has been removed otherwise, we have to continually |
| 45 |
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* "rearm" fds that we suspect *might* have changed (same |
| 46 |
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* problem with kqueue, but much less costly there). |
| 47 |
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* b) the fact that ADD != MOD creates a lot of extra syscalls due to a) |
| 48 |
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* and seems not to have any advantage. |
| 49 |
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* c) the inability to handle fork or file descriptors (think dup) |
| 50 |
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* limits the applicability over poll, so this is not a generic |
| 51 |
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* poll replacement. |
| 52 |
root |
1.50 |
* d) epoll doesn't work the same as select with many file descriptors |
| 53 |
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* (such as files). while not critical, no other advanced interface |
| 54 |
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* seems to share this (rather non-unixy) limitation. |
| 55 |
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* e) epoll claims to be embeddable, but in practise you never get |
| 56 |
root |
1.55 |
* a ready event for the epoll fd (broken: <=2.6.26, working: >=2.6.32). |
| 57 |
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* f) epoll_ctl returning EPERM means the fd is always ready. |
| 58 |
root |
1.32 |
* |
| 59 |
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* lots of "weird code" and complication handling in this file is due |
| 60 |
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* to these design problems with epoll, as we try very hard to avoid |
| 61 |
root |
1.37 |
* epoll_ctl syscalls for common usage patterns and handle the breakage |
| 62 |
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* ensuing from receiving events for closed and otherwise long gone |
| 63 |
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* file descriptors. |
| 64 |
root |
1.32 |
*/ |
| 65 |
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| 66 |
root |
1.1 |
#include <sys/epoll.h> |
| 67 |
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| 68 |
root |
1.55 |
#define EV_EMASK_EPERM 0x80 |
| 69 |
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| 70 |
root |
1.1 |
static void |
| 71 |
root |
1.13 |
epoll_modify (EV_P_ int fd, int oev, int nev) |
| 72 |
root |
1.1 |
{ |
| 73 |
root |
1.32 |
struct epoll_event ev; |
| 74 |
root |
1.35 |
unsigned char oldmask; |
| 75 |
root |
1.32 |
|
| 76 |
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/* |
| 77 |
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* we handle EPOLL_CTL_DEL by ignoring it here |
| 78 |
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* on the assumption that the fd is gone anyways |
| 79 |
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* if that is wrong, we have to handle the spurious |
| 80 |
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* event in epoll_poll. |
| 81 |
root |
1.43 |
* if the fd is added again, we try to ADD it, and, if that |
| 82 |
root |
1.35 |
* fails, we assume it still has the same eventmask. |
| 83 |
root |
1.32 |
*/ |
| 84 |
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if (!nev) |
| 85 |
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return; |
| 86 |
root |
1.1 |
|
| 87 |
root |
1.35 |
oldmask = anfds [fd].emask; |
| 88 |
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anfds [fd].emask = nev; |
| 89 |
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| 90 |
root |
1.42 |
/* store the generation counter in the upper 32 bits, the fd in the lower 32 bits */ |
| 91 |
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ev.data.u64 = (uint64_t)(uint32_t)fd |
| 92 |
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| ((uint64_t)(uint32_t)++anfds [fd].egen << 32); |
| 93 |
root |
1.32 |
ev.events = (nev & EV_READ ? EPOLLIN : 0) |
| 94 |
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| (nev & EV_WRITE ? EPOLLOUT : 0); |
| 95 |
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| 96 |
root |
1.77 |
if (ecb_expect_true (!epoll_ctl (backend_fd, oev && oldmask != nev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev))) |
| 97 |
root |
1.32 |
return; |
| 98 |
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| 99 |
root |
1.77 |
if (ecb_expect_true (errno == ENOENT)) |
| 100 |
root |
1.32 |
{ |
| 101 |
root |
1.35 |
/* if ENOENT then the fd went away, so try to do the right thing */ |
| 102 |
root |
1.32 |
if (!nev) |
| 103 |
root |
1.36 |
goto dec_egen; |
| 104 |
root |
1.32 |
|
| 105 |
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if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)) |
| 106 |
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return; |
| 107 |
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} |
| 108 |
root |
1.77 |
else if (ecb_expect_true (errno == EEXIST)) |
| 109 |
root |
1.32 |
{ |
| 110 |
root |
1.35 |
/* EEXIST means we ignored a previous DEL, but the fd is still active */ |
| 111 |
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/* if the kernel mask is the same as the new mask, we assume it hasn't changed */ |
| 112 |
root |
1.36 |
if (oldmask == nev) |
| 113 |
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goto dec_egen; |
| 114 |
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| 115 |
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if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev)) |
| 116 |
root |
1.32 |
return; |
| 117 |
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} |
| 118 |
root |
1.77 |
else if (ecb_expect_true (errno == EPERM)) |
| 119 |
root |
1.55 |
{ |
| 120 |
root |
1.57 |
/* EPERM means the fd is always ready, but epoll is too snobbish */ |
| 121 |
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/* to handle it, unlike select or poll. */ |
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root |
1.55 |
anfds [fd].emask = EV_EMASK_EPERM; |
| 123 |
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| 124 |
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/* add fd to epoll_eperms, if not already inside */ |
| 125 |
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if (!(oldmask & EV_EMASK_EPERM)) |
| 126 |
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{ |
| 127 |
root |
1.73 |
array_needsize (int, epoll_eperms, epoll_epermmax, epoll_epermcnt + 1, array_needsize_noinit); |
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root |
1.55 |
epoll_eperms [epoll_epermcnt++] = fd; |
| 129 |
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} |
| 130 |
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| 131 |
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return; |
| 132 |
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} |
| 133 |
root |
1.76 |
else |
| 134 |
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assert (("libev: I/O watcher with invalid fd found in epoll_ctl", errno != EBADF && errno != ELOOP && errno != EINVAL)); |
| 135 |
root |
1.32 |
|
| 136 |
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fd_kill (EV_A_ fd); |
| 137 |
root |
1.36 |
|
| 138 |
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dec_egen: |
| 139 |
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/* we didn't successfully call epoll_ctl, so decrement the generation counter again */ |
| 140 |
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--anfds [fd].egen; |
| 141 |
root |
1.1 |
} |
| 142 |
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| 143 |
root |
1.6 |
static void |
| 144 |
root |
1.13 |
epoll_poll (EV_P_ ev_tstamp timeout) |
| 145 |
root |
1.1 |
{ |
| 146 |
root |
1.20 |
int i; |
| 147 |
root |
1.44 |
int eventcnt; |
| 148 |
root |
1.58 |
|
| 149 |
root |
1.77 |
if (ecb_expect_false (epoll_epermcnt)) |
| 150 |
root |
1.62 |
timeout = 0.; |
| 151 |
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| 152 |
root |
1.48 |
/* epoll wait times cannot be larger than (LONG_MAX - 999UL) / HZ msecs, which is below */ |
| 153 |
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/* the default libev max wait time, however. */ |
| 154 |
root |
1.46 |
EV_RELEASE_CB; |
| 155 |
root |
1.62 |
eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, timeout * 1e3); |
| 156 |
root |
1.46 |
EV_ACQUIRE_CB; |
| 157 |
root |
1.1 |
|
| 158 |
root |
1.77 |
if (ecb_expect_false (eventcnt < 0)) |
| 159 |
root |
1.20 |
{ |
| 160 |
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if (errno != EINTR) |
| 161 |
root |
1.38 |
ev_syserr ("(libev) epoll_wait"); |
| 162 |
root |
1.20 |
|
| 163 |
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return; |
| 164 |
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} |
| 165 |
root |
1.1 |
|
| 166 |
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for (i = 0; i < eventcnt; ++i) |
| 167 |
root |
1.32 |
{ |
| 168 |
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struct epoll_event *ev = epoll_events + i; |
| 169 |
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| 170 |
root |
1.37 |
int fd = (uint32_t)ev->data.u64; /* mask out the lower 32 bits */ |
| 171 |
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int want = anfds [fd].events; |
| 172 |
root |
1.32 |
int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) |
| 173 |
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| (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0); |
| 174 |
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| 175 |
root |
1.64 |
/* |
| 176 |
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* check for spurious notification. |
| 177 |
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* this only finds spurious notifications on egen updates |
| 178 |
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* other spurious notifications will be found by epoll_ctl, below |
| 179 |
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* we assume that fd is always in range, as we never shrink the anfds array |
| 180 |
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*/ |
| 181 |
root |
1.77 |
if (ecb_expect_false ((uint32_t)anfds [fd].egen != (uint32_t)(ev->data.u64 >> 32))) |
| 182 |
root |
1.37 |
{ |
| 183 |
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/* recreate kernel state */ |
| 184 |
root |
1.69 |
postfork |= 2; |
| 185 |
root |
1.37 |
continue; |
| 186 |
|
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} |
| 187 |
root |
1.36 |
|
| 188 |
root |
1.77 |
if (ecb_expect_false (got & ~want)) |
| 189 |
root |
1.32 |
{ |
| 190 |
root |
1.35 |
anfds [fd].emask = want; |
| 191 |
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|
| 192 |
root |
1.64 |
/* |
| 193 |
|
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* we received an event but are not interested in it, try mod or del |
| 194 |
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* this often happens because we optimistically do not unregister fds |
| 195 |
|
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* when we are no longer interested in them, but also when we get spurious |
| 196 |
|
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* notifications for fds from another process. this is partially handled |
| 197 |
|
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* above with the gencounter check (== our fd is not the event fd), and |
| 198 |
|
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* partially here, when epoll_ctl returns an error (== a child has the fd |
| 199 |
|
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* but we closed it). |
| 200 |
|
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*/ |
| 201 |
root |
1.32 |
ev->events = (want & EV_READ ? EPOLLIN : 0) |
| 202 |
|
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| (want & EV_WRITE ? EPOLLOUT : 0); |
| 203 |
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|
| 204 |
root |
1.49 |
/* pre-2.6.9 kernels require a non-null pointer with EPOLL_CTL_DEL, */ |
| 205 |
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/* which is fortunately easy to do for us. */ |
| 206 |
root |
1.37 |
if (epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev)) |
| 207 |
|
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{ |
| 208 |
root |
1.70 |
postfork |= 2; /* an error occurred, recreate kernel state */ |
| 209 |
root |
1.37 |
continue; |
| 210 |
|
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} |
| 211 |
root |
1.32 |
} |
| 212 |
|
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|
| 213 |
|
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fd_event (EV_A_ fd, got); |
| 214 |
|
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} |
| 215 |
root |
1.1 |
|
| 216 |
|
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/* if the receive array was full, increase its size */ |
| 217 |
root |
1.77 |
if (ecb_expect_false (eventcnt == epoll_eventmax)) |
| 218 |
root |
1.1 |
{ |
| 219 |
root |
1.20 |
ev_free (epoll_events); |
| 220 |
root |
1.28 |
epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1); |
| 221 |
root |
1.23 |
epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); |
| 222 |
root |
1.1 |
} |
| 223 |
root |
1.55 |
|
| 224 |
root |
1.56 |
/* now synthesize events for all fds where epoll fails, while select works... */ |
| 225 |
root |
1.55 |
for (i = epoll_epermcnt; i--; ) |
| 226 |
|
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{ |
| 227 |
|
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int fd = epoll_eperms [i]; |
| 228 |
|
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unsigned char events = anfds [fd].events & (EV_READ | EV_WRITE); |
| 229 |
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|
| 230 |
|
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if (anfds [fd].emask & EV_EMASK_EPERM && events) |
| 231 |
|
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fd_event (EV_A_ fd, events); |
| 232 |
|
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else |
| 233 |
root |
1.68 |
{ |
| 234 |
|
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epoll_eperms [i] = epoll_eperms [--epoll_epermcnt]; |
| 235 |
|
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anfds [fd].emask = 0; |
| 236 |
|
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} |
| 237 |
root |
1.55 |
} |
| 238 |
root |
1.1 |
} |
| 239 |
|
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|
| 240 |
root |
1.74 |
static int |
| 241 |
root |
1.75 |
epoll_epoll_create (void) |
| 242 |
root |
1.1 |
{ |
| 243 |
root |
1.74 |
int fd; |
| 244 |
|
|
|
| 245 |
root |
1.72 |
#if defined EPOLL_CLOEXEC && !defined __ANDROID__ |
| 246 |
root |
1.74 |
fd = epoll_create1 (EPOLL_CLOEXEC); |
| 247 |
root |
1.47 |
|
| 248 |
root |
1.74 |
if (fd < 0 && (errno == EINVAL || errno == ENOSYS)) |
| 249 |
root |
1.47 |
#endif |
| 250 |
root |
1.74 |
{ |
| 251 |
|
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fd = epoll_create (256); |
| 252 |
|
|
|
| 253 |
|
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if (fd >= 0) |
| 254 |
|
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fcntl (fd, F_SETFD, FD_CLOEXEC); |
| 255 |
|
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} |
| 256 |
|
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|
| 257 |
|
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return fd; |
| 258 |
|
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} |
| 259 |
root |
1.1 |
|
| 260 |
root |
1.74 |
inline_size |
| 261 |
|
|
int |
| 262 |
|
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epoll_init (EV_P_ int flags) |
| 263 |
|
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{ |
| 264 |
root |
1.75 |
if ((backend_fd = epoll_epoll_create ()) < 0) |
| 265 |
root |
1.13 |
return 0; |
| 266 |
root |
1.3 |
|
| 267 |
root |
1.66 |
backend_mintime = 1e-3; /* epoll does sometimes return early, this is just to avoid the worst */ |
| 268 |
root |
1.63 |
backend_modify = epoll_modify; |
| 269 |
|
|
backend_poll = epoll_poll; |
| 270 |
root |
1.1 |
|
| 271 |
root |
1.37 |
epoll_eventmax = 64; /* initial number of events receivable per poll */ |
| 272 |
root |
1.23 |
epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); |
| 273 |
root |
1.13 |
|
| 274 |
root |
1.24 |
return EVBACKEND_EPOLL; |
| 275 |
root |
1.1 |
} |
| 276 |
root |
1.6 |
|
| 277 |
root |
1.71 |
inline_size |
| 278 |
|
|
void |
| 279 |
root |
1.15 |
epoll_destroy (EV_P) |
| 280 |
|
|
{ |
| 281 |
root |
1.20 |
ev_free (epoll_events); |
| 282 |
root |
1.55 |
array_free (epoll_eperm, EMPTY); |
| 283 |
root |
1.15 |
} |
| 284 |
|
|
|
| 285 |
root |
1.71 |
inline_size |
| 286 |
|
|
void |
| 287 |
root |
1.15 |
epoll_fork (EV_P) |
| 288 |
|
|
{ |
| 289 |
root |
1.26 |
close (backend_fd); |
| 290 |
root |
1.21 |
|
| 291 |
root |
1.75 |
while ((backend_fd = epoll_epoll_create ()) < 0) |
| 292 |
root |
1.38 |
ev_syserr ("(libev) epoll_create"); |
| 293 |
root |
1.21 |
|
| 294 |
root |
1.16 |
fd_rearm_all (EV_A); |
| 295 |
root |
1.15 |
} |
| 296 |
|
|
|