ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/libev/ev_epoll.c
(Generate patch)

Comparing libev/ev_epoll.c (file contents):
Revision 1.33 by root, Tue Dec 25 07:05:45 2007 UTC vs.
Revision 1.41 by root, Wed Oct 29 07:10:16 2008 UTC

1/* 1/*
2 * libev epoll fd activity backend 2 * libev epoll fd activity backend
3 * 3 *
4 * Copyright (c) 2007 Marc Alexander Lehmann <libev@schmorp.de> 4 * Copyright (c) 2007,2008 Marc Alexander Lehmann <libev@schmorp.de>
5 * All rights reserved. 5 * All rights reserved.
6 * 6 *
7 * Redistribution and use in source and binary forms, with or without modifica- 7 * Redistribution and use in source and binary forms, with or without modifica-
8 * tion, are permitted provided that the following conditions are met: 8 * tion, are permitted provided that the following conditions are met:
9 * 9 *
… …
50 * limits the applicability over poll, so this is not a generic 50 * limits the applicability over poll, so this is not a generic
51 * poll replacement. 51 * poll replacement.
52 * 52 *
53 * lots of "weird code" and complication handling in this file is due 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 54 * to these design problems with epoll, as we try very hard to avoid
55 * epoll_ctl syscalls for common usage patterns. 55 * epoll_ctl syscalls for common usage patterns and handle the breakage
56 * ensuing from receiving events for closed and otherwise long gone
57 * file descriptors.
56 */ 58 */
57 59
58#include <sys/epoll.h> 60#include <sys/epoll.h>
59 61
60static void 62static void
61epoll_modify (EV_P_ int fd, int oev, int nev) 63epoll_modify (EV_P_ int fd, int oev, int nev)
62{ 64{
63 struct epoll_event ev; 65 struct epoll_event ev;
66 unsigned char oldmask;
64 67
65 /* 68 /*
66 * we handle EPOLL_CTL_DEL by ignoring it here 69 * we handle EPOLL_CTL_DEL by ignoring it here
67 * on the assumption that the fd is gone anyways 70 * on the assumption that the fd is gone anyways
68 * if that is wrong, we have to handle the spurious 71 * if that is wrong, we have to handle the spurious
69 * event in epoll_poll. 72 * event in epoll_poll.
73 * the fd is later added, we try to ADD it, and, if that
74 * fails, we assume it still has the same eventmask.
70 */ 75 */
71 if (!nev) 76 if (!nev)
72 return; 77 return;
73 78
74 ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */ 79 oldmask = anfds [fd].emask;
80 anfds [fd].emask = nev;
81
82 /* store the generation counter in the upper 32 bits */
83 ev.data.u64 = (uint64_t)(uint32_t)fd | ((uint64_t)(uint32_t)++anfds [fd].egen << 32);
75 ev.events = (nev & EV_READ ? EPOLLIN : 0) 84 ev.events = (nev & EV_READ ? EPOLLIN : 0)
76 | (nev & EV_WRITE ? EPOLLOUT : 0); 85 | (nev & EV_WRITE ? EPOLLOUT : 0);
77 86
78 if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev))) 87 if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev)))
79 return; 88 return;
80 89
81 if (expect_true (errno == ENOENT)) 90 if (expect_true (errno == ENOENT))
82 { 91 {
83 /* on ENOENT the fd went away, so try to do the right thing */ 92 /* if ENOENT then the fd went away, so try to do the right thing */
84 if (!nev) 93 if (!nev)
85 return; 94 goto dec_egen;
86 95
87 if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)) 96 if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev))
88 return; 97 return;
89 } 98 }
90 else if (expect_true (errno == EEXIST)) 99 else if (expect_true (errno == EEXIST))
91 { 100 {
92 /* on EEXIST we ignored a previous DEL */ 101 /* EEXIST means we ignored a previous DEL, but the fd is still active */
102 /* if the kernel mask is the same as the new mask, we assume it hasn't changed */
103 if (oldmask == nev)
104 goto dec_egen;
105
93 if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev)) 106 if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev))
94 return; 107 return;
95 } 108 }
96 109
97 fd_kill (EV_A_ fd); 110 fd_kill (EV_A_ fd);
111
112dec_egen:
113 /* we didn't successfully call epoll_ctl, so decrement the generation counter again */
114 --anfds [fd].egen;
98} 115}
99 116
100static void 117static void
101epoll_poll (EV_P_ ev_tstamp timeout) 118epoll_poll (EV_P_ ev_tstamp timeout)
102{ 119{
… …
104 int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.)); 121 int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.));
105 122
106 if (expect_false (eventcnt < 0)) 123 if (expect_false (eventcnt < 0))
107 { 124 {
108 if (errno != EINTR) 125 if (errno != EINTR)
109 syserr ("(libev) epoll_wait"); 126 ev_syserr ("(libev) epoll_wait");
110 127
111 return; 128 return;
112 } 129 }
113 130
114 for (i = 0; i < eventcnt; ++i) 131 for (i = 0; i < eventcnt; ++i)
115 { 132 {
116 struct epoll_event *ev = epoll_events + i; 133 struct epoll_event *ev = epoll_events + i;
117 134
118 int fd = ev->data.u64; 135 int fd = (uint32_t)ev->data.u64; /* mask out the lower 32 bits */
136 int want = anfds [fd].events;
119 int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) 137 int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
120 | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0); 138 | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0);
121 int want = anfds [fd].events; 139
140 /* check for spurious notification */
141 if (expect_false ((uint32_t)anfds [fd].egen != (uint32_t)(ev->data.u64 >> 32)))
142 {
143 /* recreate kernel state */
144 postfork = 1;
145 continue;
146 }
122 147
123 if (expect_false (got & ~want)) 148 if (expect_false (got & ~want))
124 { 149 {
150 anfds [fd].emask = want;
151
125 /* we received an event but are not interested in it, try mod or del */ 152 /* we received an event but are not interested in it, try mod or del */
153 /* I don't think we ever need MOD, but let's handle it anyways */
126 ev->events = (want & EV_READ ? EPOLLIN : 0) 154 ev->events = (want & EV_READ ? EPOLLIN : 0)
127 | (want & EV_WRITE ? EPOLLOUT : 0); 155 | (want & EV_WRITE ? EPOLLOUT : 0);
128 156
129 epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev); 157 if (epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev))
158 {
159 postfork = 1; /* an error occured, recreate kernel state */
160 continue;
161 }
130 } 162 }
131 163
132 fd_event (EV_A_ fd, got); 164 fd_event (EV_A_ fd, got);
133 } 165 }
134 166
… …
153 185
154 backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */ 186 backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */
155 backend_modify = epoll_modify; 187 backend_modify = epoll_modify;
156 backend_poll = epoll_poll; 188 backend_poll = epoll_poll;
157 189
158 epoll_eventmax = 64; /* intiial number of events receivable per poll */ 190 epoll_eventmax = 64; /* initial number of events receivable per poll */
159 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); 191 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
160 192
161 return EVBACKEND_EPOLL; 193 return EVBACKEND_EPOLL;
162} 194}
163 195
… …
171epoll_fork (EV_P) 203epoll_fork (EV_P)
172{ 204{
173 close (backend_fd); 205 close (backend_fd);
174 206
175 while ((backend_fd = epoll_create (256)) < 0) 207 while ((backend_fd = epoll_create (256)) < 0)
176 syserr ("(libev) epoll_create"); 208 ev_syserr ("(libev) epoll_create");
177 209
178 fcntl (backend_fd, F_SETFD, FD_CLOEXEC); 210 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
179 211
180 fd_rearm_all (EV_A); 212 fd_rearm_all (EV_A);
181} 213}

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines