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/* |
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* libev epoll fd activity backend |
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* |
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* Copyright (c) 2007,2008,2009,2010,2011,2016,2017,2019 Marc Alexander Lehmann |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without modifica- |
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* tion, are permitted provided that the following conditions are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright notice, |
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* this list of conditions and the following disclaimer. |
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* |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- |
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* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- |
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* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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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. |
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* |
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* Alternatively, the contents of this file may be used under the terms of |
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* the GNU General Public License ("GPL") version 2 or any later version, |
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* in which case the provisions of the GPL are applicable instead of |
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* the above. If you wish to allow the use of your version of this file |
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* only under the terms of the GPL and not to allow others to use your |
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* version of this file under the BSD license, indicate your decision |
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* by deleting the provisions above and replace them with the notice |
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* and other provisions required by the GPL. If you do not delete the |
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* provisions above, a recipient may use your version of this file under |
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* either the BSD or the GPL. |
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*/ |
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40
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/* |
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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
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* 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
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* 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
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* |
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
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* 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
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*/ |
65
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66
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#include |
67
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68
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#define EV_EMASK_EPERM 0x80 |
69
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70
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static void |
71
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8
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epoll_modify (EV_P_ int fd, int oev, int nev) |
72
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{ |
73
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struct epoll_event ev; |
74
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unsigned char oldmask; |
75
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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
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* if the fd is added again, we try to ADD it, and, if that |
82
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* fails, we assume it still has the same eventmask. |
83
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*/ |
84
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8
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50
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if (!nev) |
85
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8
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return; |
86
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87
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8
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oldmask = anfds [fd].emask; |
88
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8
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anfds [fd].emask = nev; |
89
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90
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/* store the generation counter in the upper 32 bits, the fd in the lower 32 bits */ |
91
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24
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ev.data.u64 = (uint64_t)(uint32_t)fd |
92
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16
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| ((uint64_t)(uint32_t)++anfds [fd].egen << 32); |
93
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16
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ev.events = (nev & EV_READ ? EPOLLIN : 0) |
94
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8
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50
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| (nev & EV_WRITE ? EPOLLOUT : 0); |
95
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96
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8
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50
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if (ecb_expect_true (!epoll_ctl (backend_fd, oev && oldmask != nev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev))) |
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0
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50
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97
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8
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return; |
98
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99
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0
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0
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if (ecb_expect_true (errno == ENOENT)) |
100
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{ |
101
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/* if ENOENT then the fd went away, so try to do the right thing */ |
102
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0
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0
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if (!nev) |
103
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0
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goto dec_egen; |
104
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105
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0
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0
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if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)) |
106
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0
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return; |
107
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} |
108
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0
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0
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else if (ecb_expect_true (errno == EEXIST)) |
109
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{ |
110
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/* 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
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0
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0
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if (oldmask == nev) |
113
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0
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goto dec_egen; |
114
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115
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0
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0
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if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev)) |
116
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0
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return; |
117
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} |
118
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0
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0
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else if (ecb_expect_true (errno == EPERM)) |
119
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{ |
120
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/* EPERM means the fd is always ready, but epoll is too snobbish */ |
121
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/* to handle it, unlike select or poll. */ |
122
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0
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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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0
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0
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if (!(oldmask & EV_EMASK_EPERM)) |
126
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{ |
127
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0
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0
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array_needsize (int, epoll_eperms, epoll_epermmax, epoll_epermcnt + 1, array_needsize_noinit); |
128
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0
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epoll_eperms [epoll_epermcnt++] = fd; |
129
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} |
130
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131
|
0
|
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return; |
132
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|
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} |
133
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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
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136
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0
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fd_kill (EV_A_ fd); |
137
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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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0
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--anfds [fd].egen; |
141
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} |
142
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143
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static void |
144
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19
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epoll_poll (EV_P_ ev_tstamp timeout) |
145
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{ |
146
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int i; |
147
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int eventcnt; |
148
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149
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19
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50
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if (ecb_expect_false (epoll_epermcnt)) |
150
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0
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timeout = EV_TS_CONST (0.); |
151
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152
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/* 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
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19
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50
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EV_RELEASE_CB; |
155
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19
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eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, EV_TS_TO_MSEC (timeout)); |
156
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19
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50
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EV_ACQUIRE_CB; |
157
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158
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19
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50
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if (ecb_expect_false (eventcnt < 0)) |
159
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|
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{ |
160
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0
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0
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if (errno != EINTR) |
161
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0
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ev_syserr ("(libev) epoll_wait"); |
162
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|
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163
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0
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return; |
164
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|
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} |
165
|
|
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166
|
20
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100
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for (i = 0; i < eventcnt; ++i) |
167
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|
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{ |
168
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1
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struct epoll_event *ev = epoll_events + i; |
169
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|
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170
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1
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int fd = (uint32_t)ev->data.u64; /* mask out the lower 32 bits */ |
171
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1
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int want = anfds [fd].events; |
172
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1
|
50
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int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) |
173
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1
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|
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| (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0); |
174
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|
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175
|
|
|
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/* |
176
|
|
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|
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* check for spurious notification. |
177
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|
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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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|
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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
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1
|
50
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|
|
|
|
if (ecb_expect_false ((uint32_t)anfds [fd].egen != (uint32_t)(ev->data.u64 >> 32))) |
182
|
|
|
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{ |
183
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|
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|
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/* recreate kernel state */ |
184
|
0
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|
|
|
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|
postfork |= 2; |
185
|
0
|
|
|
|
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|
continue; |
186
|
|
|
|
|
|
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} |
187
|
|
|
|
|
|
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|
188
|
1
|
50
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|
|
|
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if (ecb_expect_false (got & ~want)) |
189
|
|
|
|
|
|
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{ |
190
|
0
|
|
|
|
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|
anfds [fd].emask = want; |
191
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|
|
|
|
|
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|
192
|
|
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|
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/* |
193
|
|
|
|
|
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* we received an event but are not interested in it, try mod or del |
194
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|
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* this often happens because we optimistically do not unregister fds |
195
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|
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|
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* when we are no longer interested in them, but also when we get spurious |
196
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|
|
|
|
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* notifications for fds from another process. this is partially handled |
197
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|
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|
|
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* above with the gencounter check (== our fd is not the event fd), and |
198
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|
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|
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* partially here, when epoll_ctl returns an error (== a child has the fd |
199
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|
|
|
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* but we closed it). |
200
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|
|
|
|
|
|
* note: for events such as POLLHUP, where we can't know whether it refers |
201
|
|
|
|
|
|
|
* to EV_READ or EV_WRITE, we might issue redundant EPOLL_CTL_MOD calls. |
202
|
|
|
|
|
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*/ |
203
|
0
|
|
|
|
|
|
ev->events = (want & EV_READ ? EPOLLIN : 0) |
204
|
0
|
0
|
|
|
|
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| (want & EV_WRITE ? EPOLLOUT : 0); |
205
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|
|
|
|
|
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|
206
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|
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/* pre-2.6.9 kernels require a non-null pointer with EPOLL_CTL_DEL, */ |
207
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|
|
|
|
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/* which is fortunately easy to do for us. */ |
208
|
0
|
0
|
|
|
|
|
if (epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev)) |
|
|
0
|
|
|
|
|
|
209
|
|
|
|
|
|
|
{ |
210
|
0
|
|
|
|
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|
postfork |= 2; /* an error occurred, recreate kernel state */ |
211
|
0
|
|
|
|
|
|
continue; |
212
|
|
|
|
|
|
|
} |
213
|
|
|
|
|
|
|
} |
214
|
|
|
|
|
|
|
|
215
|
1
|
|
|
|
|
|
fd_event (EV_A_ fd, got); |
216
|
|
|
|
|
|
|
} |
217
|
|
|
|
|
|
|
|
218
|
|
|
|
|
|
|
/* if the receive array was full, increase its size */ |
219
|
19
|
50
|
|
|
|
|
if (ecb_expect_false (eventcnt == epoll_eventmax)) |
220
|
|
|
|
|
|
|
{ |
221
|
0
|
|
|
|
|
|
ev_free (epoll_events); |
222
|
0
|
|
|
|
|
|
epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1); |
223
|
0
|
|
|
|
|
|
epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); |
224
|
|
|
|
|
|
|
} |
225
|
|
|
|
|
|
|
|
226
|
|
|
|
|
|
|
/* now synthesize events for all fds where epoll fails, while select works... */ |
227
|
19
|
50
|
|
|
|
|
for (i = epoll_epermcnt; i--; ) |
228
|
|
|
|
|
|
|
{ |
229
|
0
|
|
|
|
|
|
int fd = epoll_eperms [i]; |
230
|
0
|
|
|
|
|
|
unsigned char events = anfds [fd].events & (EV_READ | EV_WRITE); |
231
|
|
|
|
|
|
|
|
232
|
0
|
0
|
|
|
|
|
if (anfds [fd].emask & EV_EMASK_EPERM && events) |
|
|
0
|
|
|
|
|
|
233
|
0
|
|
|
|
|
|
fd_event (EV_A_ fd, events); |
234
|
|
|
|
|
|
|
else |
235
|
|
|
|
|
|
|
{ |
236
|
0
|
|
|
|
|
|
epoll_eperms [i] = epoll_eperms [--epoll_epermcnt]; |
237
|
0
|
|
|
|
|
|
anfds [fd].emask = 0; |
238
|
|
|
|
|
|
|
} |
239
|
|
|
|
|
|
|
} |
240
|
|
|
|
|
|
|
} |
241
|
|
|
|
|
|
|
|
242
|
|
|
|
|
|
|
static int |
243
|
7
|
|
|
|
|
|
epoll_epoll_create (void) |
244
|
|
|
|
|
|
|
{ |
245
|
|
|
|
|
|
|
int fd; |
246
|
|
|
|
|
|
|
|
247
|
|
|
|
|
|
|
#if defined EPOLL_CLOEXEC && !defined __ANDROID__ |
248
|
7
|
|
|
|
|
|
fd = epoll_create1 (EPOLL_CLOEXEC); |
249
|
|
|
|
|
|
|
|
250
|
7
|
50
|
|
|
|
|
if (fd < 0 && (errno == EINVAL || errno == ENOSYS)) |
|
|
0
|
|
|
|
|
|
|
|
0
|
|
|
|
|
|
251
|
|
|
|
|
|
|
#endif |
252
|
|
|
|
|
|
|
{ |
253
|
0
|
|
|
|
|
|
fd = epoll_create (256); |
254
|
|
|
|
|
|
|
|
255
|
0
|
0
|
|
|
|
|
if (fd >= 0) |
256
|
0
|
|
|
|
|
|
fcntl (fd, F_SETFD, FD_CLOEXEC); |
257
|
|
|
|
|
|
|
} |
258
|
|
|
|
|
|
|
|
259
|
7
|
|
|
|
|
|
return fd; |
260
|
|
|
|
|
|
|
} |
261
|
|
|
|
|
|
|
|
262
|
|
|
|
|
|
|
inline_size |
263
|
|
|
|
|
|
|
int |
264
|
7
|
|
|
|
|
|
epoll_init (EV_P_ int flags) |
265
|
|
|
|
|
|
|
{ |
266
|
7
|
50
|
|
|
|
|
if ((backend_fd = epoll_epoll_create ()) < 0) |
267
|
0
|
|
|
|
|
|
return 0; |
268
|
|
|
|
|
|
|
|
269
|
7
|
|
|
|
|
|
backend_mintime = EV_TS_CONST (1e-3); /* epoll does sometimes return early, this is just to avoid the worst */ |
270
|
7
|
|
|
|
|
|
backend_modify = epoll_modify; |
271
|
7
|
|
|
|
|
|
backend_poll = epoll_poll; |
272
|
|
|
|
|
|
|
|
273
|
7
|
|
|
|
|
|
epoll_eventmax = 64; /* initial number of events receivable per poll */ |
274
|
7
|
|
|
|
|
|
epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); |
275
|
|
|
|
|
|
|
|
276
|
7
|
|
|
|
|
|
return EVBACKEND_EPOLL; |
277
|
|
|
|
|
|
|
} |
278
|
|
|
|
|
|
|
|
279
|
|
|
|
|
|
|
inline_size |
280
|
|
|
|
|
|
|
void |
281
|
2
|
|
|
|
|
|
epoll_destroy (EV_P) |
282
|
|
|
|
|
|
|
{ |
283
|
2
|
|
|
|
|
|
ev_free (epoll_events); |
284
|
2
|
|
|
|
|
|
array_free (epoll_eperm, EMPTY); |
285
|
2
|
|
|
|
|
|
} |
286
|
|
|
|
|
|
|
|
287
|
|
|
|
|
|
|
ecb_cold |
288
|
|
|
|
|
|
|
static void |
289
|
0
|
|
|
|
|
|
epoll_fork (EV_P) |
290
|
|
|
|
|
|
|
{ |
291
|
0
|
|
|
|
|
|
close (backend_fd); |
292
|
|
|
|
|
|
|
|
293
|
0
|
0
|
|
|
|
|
while ((backend_fd = epoll_epoll_create ()) < 0) |
294
|
0
|
|
|
|
|
|
ev_syserr ("(libev) epoll_create"); |
295
|
|
|
|
|
|
|
|
296
|
0
|
|
|
|
|
|
fd_rearm_all (EV_A); |
297
|
0
|
|
|
|
|
|
} |
298
|
|
|
|
|
|
|
|