devpoll.c (7889B)
1 /* 2 * Copyright 2000-2009 Niels Provos <provos@citi.umich.edu> 3 * Copyright 2009-2012 Niels Provos and Nick Mathewson 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 #include "event2/event-config.h" 28 #include "evconfig-private.h" 29 30 #ifdef EVENT__HAVE_DEVPOLL 31 32 #include <sys/types.h> 33 #include <sys/resource.h> 34 #ifdef EVENT__HAVE_SYS_TIME_H 35 #include <sys/time.h> 36 #endif 37 #include <sys/queue.h> 38 #include <sys/devpoll.h> 39 #include <signal.h> 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <unistd.h> 44 #include <fcntl.h> 45 #include <errno.h> 46 47 #include "event2/event.h" 48 #include "event2/event_struct.h" 49 #include "event2/thread.h" 50 #include "event-internal.h" 51 #include "evsignal-internal.h" 52 #include "log-internal.h" 53 #include "evmap-internal.h" 54 #include "evthread-internal.h" 55 56 struct devpollop { 57 struct pollfd *events; 58 int nevents; 59 int dpfd; 60 struct pollfd *changes; 61 int nchanges; 62 }; 63 64 static void *devpoll_init(struct event_base *); 65 static int devpoll_add(struct event_base *, int fd, short old, short events, void *); 66 static int devpoll_del(struct event_base *, int fd, short old, short events, void *); 67 static int devpoll_dispatch(struct event_base *, struct timeval *); 68 static void devpoll_dealloc(struct event_base *); 69 70 const struct eventop devpollops = { 71 "devpoll", 72 devpoll_init, 73 devpoll_add, 74 devpoll_del, 75 devpoll_dispatch, 76 devpoll_dealloc, 77 1, /* need reinit */ 78 EV_FEATURE_FDS|EV_FEATURE_O1, 79 0 80 }; 81 82 #define NEVENT 32000 83 84 static int 85 devpoll_commit(struct devpollop *devpollop) 86 { 87 /* 88 * Due to a bug in Solaris, we have to use pwrite with an offset of 0. 89 * Write is limited to 2GB of data, until it will fail. 90 */ 91 if (pwrite(devpollop->dpfd, devpollop->changes, 92 sizeof(struct pollfd) * devpollop->nchanges, 0) == -1) 93 return (-1); 94 95 devpollop->nchanges = 0; 96 return (0); 97 } 98 99 static int 100 devpoll_queue(struct devpollop *devpollop, int fd, int events) { 101 struct pollfd *pfd; 102 103 if (devpollop->nchanges >= devpollop->nevents) { 104 /* 105 * Change buffer is full, must commit it to /dev/poll before 106 * adding more 107 */ 108 if (devpoll_commit(devpollop) != 0) 109 return (-1); 110 } 111 112 pfd = &devpollop->changes[devpollop->nchanges++]; 113 pfd->fd = fd; 114 pfd->events = events; 115 pfd->revents = 0; 116 117 return (0); 118 } 119 120 static void * 121 devpoll_init(struct event_base *base) 122 { 123 int dpfd, nfiles = NEVENT; 124 struct rlimit rl; 125 struct devpollop *devpollop; 126 127 if (!(devpollop = mm_calloc(1, sizeof(struct devpollop)))) 128 return (NULL); 129 130 if (getrlimit(RLIMIT_NOFILE, &rl) == 0 && 131 rl.rlim_cur != RLIM_INFINITY) 132 nfiles = rl.rlim_cur; 133 134 /* Initialize the kernel queue */ 135 if ((dpfd = evutil_open_closeonexec_("/dev/poll", O_RDWR, 0)) == -1) { 136 event_warn("open: /dev/poll"); 137 mm_free(devpollop); 138 return (NULL); 139 } 140 141 devpollop->dpfd = dpfd; 142 143 /* Initialize fields */ 144 /* FIXME: allocating 'nfiles' worth of space here can be 145 * expensive and unnecessary. See how epoll.c does it instead. */ 146 devpollop->events = mm_calloc(nfiles, sizeof(struct pollfd)); 147 if (devpollop->events == NULL) { 148 mm_free(devpollop); 149 close(dpfd); 150 return (NULL); 151 } 152 devpollop->nevents = nfiles; 153 154 devpollop->changes = mm_calloc(nfiles, sizeof(struct pollfd)); 155 if (devpollop->changes == NULL) { 156 mm_free(devpollop->events); 157 mm_free(devpollop); 158 close(dpfd); 159 return (NULL); 160 } 161 162 evsig_init_(base); 163 164 return (devpollop); 165 } 166 167 static int 168 devpoll_dispatch(struct event_base *base, struct timeval *tv) 169 { 170 struct devpollop *devpollop = base->evbase; 171 struct pollfd *events = devpollop->events; 172 struct dvpoll dvp; 173 int i, res, timeout = -1; 174 175 if (devpollop->nchanges) 176 devpoll_commit(devpollop); 177 178 if (tv != NULL) 179 timeout = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000; 180 181 dvp.dp_fds = devpollop->events; 182 dvp.dp_nfds = devpollop->nevents; 183 dvp.dp_timeout = timeout; 184 185 EVBASE_RELEASE_LOCK(base, th_base_lock); 186 187 res = ioctl(devpollop->dpfd, DP_POLL, &dvp); 188 189 EVBASE_ACQUIRE_LOCK(base, th_base_lock); 190 191 if (res == -1) { 192 if (errno != EINTR) { 193 event_warn("ioctl: DP_POLL"); 194 return (-1); 195 } 196 197 return (0); 198 } 199 200 event_debug(("%s: devpoll_wait reports %d", __func__, res)); 201 202 for (i = 0; i < res; i++) { 203 int which = 0; 204 int what = events[i].revents; 205 206 if (what & POLLHUP) 207 what |= POLLIN | POLLOUT; 208 else if (what & POLLERR) 209 what |= POLLIN | POLLOUT; 210 211 if (what & POLLIN) 212 which |= EV_READ; 213 if (what & POLLOUT) 214 which |= EV_WRITE; 215 216 if (!which) 217 continue; 218 219 /* XXX(niels): not sure if this works for devpoll */ 220 evmap_io_active_(base, events[i].fd, which); 221 } 222 223 return (0); 224 } 225 226 227 static int 228 devpoll_add(struct event_base *base, int fd, short old, short events, void *p) 229 { 230 struct devpollop *devpollop = base->evbase; 231 int res; 232 (void)p; 233 234 /* 235 * It's not necessary to OR the existing read/write events that we 236 * are currently interested in with the new event we are adding. 237 * The /dev/poll driver ORs any new events with the existing events 238 * that it has cached for the fd. 239 */ 240 241 res = 0; 242 if (events & EV_READ) 243 res |= POLLIN; 244 if (events & EV_WRITE) 245 res |= POLLOUT; 246 247 if (devpoll_queue(devpollop, fd, res) != 0) 248 return (-1); 249 250 return (0); 251 } 252 253 static int 254 devpoll_del(struct event_base *base, int fd, short old, short events, void *p) 255 { 256 struct devpollop *devpollop = base->evbase; 257 int res; 258 (void)p; 259 260 res = 0; 261 if (events & EV_READ) 262 res |= POLLIN; 263 if (events & EV_WRITE) 264 res |= POLLOUT; 265 266 /* 267 * The only way to remove an fd from the /dev/poll monitored set is 268 * to use POLLREMOVE by itself. This removes ALL events for the fd 269 * provided so if we care about two events and are only removing one 270 * we must re-add the other event after POLLREMOVE. 271 */ 272 273 if (devpoll_queue(devpollop, fd, POLLREMOVE) != 0) 274 return (-1); 275 276 if ((res & (POLLIN|POLLOUT)) != (POLLIN|POLLOUT)) { 277 /* 278 * We're not deleting all events, so we must resubmit the 279 * event that we are still interested in if one exists. 280 */ 281 282 if ((res & POLLIN) && (old & EV_WRITE)) { 283 /* Deleting read, still care about write */ 284 devpoll_queue(devpollop, fd, POLLOUT); 285 } else if ((res & POLLOUT) && (old & EV_READ)) { 286 /* Deleting write, still care about read */ 287 devpoll_queue(devpollop, fd, POLLIN); 288 } 289 } 290 291 return (0); 292 } 293 294 static void 295 devpoll_dealloc(struct event_base *base) 296 { 297 struct devpollop *devpollop = base->evbase; 298 299 evsig_dealloc_(base); 300 if (devpollop->events) 301 mm_free(devpollop->events); 302 if (devpollop->changes) 303 mm_free(devpollop->changes); 304 if (devpollop->dpfd >= 0) 305 close(devpollop->dpfd); 306 307 memset(devpollop, 0, sizeof(struct devpollop)); 308 mm_free(devpollop); 309 } 310 311 #endif /* EVENT__HAVE_DEVPOLL */