third_party/libevent/epoll.c

   1 /*
   2  * Copyright 2000-2003 Niels Provos <provos@citi.umich.edu>
   3  * All rights reserved.
   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 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <stdint.h>
  32 #include <sys/types.h>
  33 #include <sys/resource.h>
  34 #ifdef HAVE_SYS_TIME_H
  35 #include <sys/time.h>
  36 #else
  37 #include <sys/_libevent_time.h>
  38 #endif
  39 #include <sys/queue.h>
  40 #include <sys/epoll.h>
  41 #include <signal.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <unistd.h>
  46 #include <errno.h>
  47 #ifdef HAVE_FCNTL_H
  48 #include <fcntl.h>
  49 #endif
  50
  51 #include "event.h"
  52 #include "event-internal.h"
  53 #include "evsignal.h"
  54 #include "log.h"
  55
  56 /* due to limitations in the epoll interface, we need to keep track of
  57  * all file descriptors outself.
  58  */
  59 struct evepoll {
  60         struct event *evread;
  61         struct event *evwrite;
  62 };
  63
  64 struct epollop {
  65         struct evepoll *fds;
  66         int nfds;
  67         struct epoll_event *events;
  68         int nevents;
  69         int epfd;
  70 };
  71
  72 static void *epoll_init (struct event_base *);
  73 static int epoll_add    (void *, struct event *);
  74 static int epoll_del    (void *, struct event *);
  75 static int epoll_dispatch       (struct event_base *, void *, struct timeval *);
  76 static void epoll_dealloc       (struct event_base *, void *);
  77
  78 const struct eventop epollops = {
  79         "epoll",
  80         epoll_init,
  81         epoll_add,
  82         epoll_del,
  83         epoll_dispatch,
  84         epoll_dealloc,
  85         1 /* need reinit */
  86 };
  87
  88 #ifdef HAVE_SETFD
  89 #define FD_CLOSEONEXEC(x) do { \
  90         if (fcntl(x, F_SETFD, 1) == -1) \
  91                 event_warn("fcntl(%d, F_SETFD)", x); \
  92 } while (0)
  93 #else
  94 #define FD_CLOSEONEXEC(x)
  95 #endif
  96
  97 /* On Linux kernels at least up to 2.6.24.4, epoll can't handle timeout
  98  * values bigger than (LONG_MAX - 999ULL)/HZ.  HZ in the wild can be
  99  * as big as 1000, and LONG_MAX can be as small as (1<<31)-1, so the
 100  * largest number of msec we can support here is 2147482.  Let's
 101  * round that down by 47 seconds.
 102  */
 103 #define MAX_EPOLL_TIMEOUT_MSEC (35*60*1000)
 104
 105 #define INITIAL_NFILES 32
 106 #define INITIAL_NEVENTS 32
 107 #define MAX_NEVENTS 4096
 108
 109 static void *
 110 epoll_init(struct event_base *base)
 111 {
 112         int epfd;
 113         struct epollop *epollop;
 114
 115         /* Disable epollueue when this environment variable is set */
 116         if (evutil_getenv("EVENT_NOEPOLL"))
 117                 return (NULL);
 118
 119         /* Initalize the kernel queue */
 120         if ((epfd = epoll_create(32000)) == -1) {
 121                 if (errno != ENOSYS)
 122                         event_warn("epoll_create");
 123                 return (NULL);
 124         }
 125
 126         FD_CLOSEONEXEC(epfd);
 127
 128         if (!(epollop = calloc(1, sizeof(struct epollop))))
 129                 return (NULL);
 130
 131         epollop->epfd = epfd;
 132
 133         /* Initalize fields */
 134         epollop->events = malloc(INITIAL_NEVENTS * sizeof(struct epoll_event));
 135         if (epollop->events == NULL) {
 136                 free(epollop);
 137                 return (NULL);
 138         }
 139         epollop->nevents = INITIAL_NEVENTS;
 140
 141         epollop->fds = calloc(INITIAL_NFILES, sizeof(struct evepoll));
 142         if (epollop->fds == NULL) {
 143                 free(epollop->events);
 144                 free(epollop);
 145                 return (NULL);
 146         }
 147         epollop->nfds = INITIAL_NFILES;
 148
 149         evsignal_init(base);
 150
 151         return (epollop);
 152 }
 153
 154 static int
 155 epoll_recalc(struct event_base *base, void *arg, int max)
 156 {
 157         struct epollop *epollop = arg;
 158
 159         if (max >= epollop->nfds) {
 160                 struct evepoll *fds;
 161                 int nfds;
 162
 163                 nfds = epollop->nfds;
 164                 while (nfds <= max)
 165                         nfds <<= 1;
 166
 167                 fds = realloc(epollop->fds, nfds * sizeof(struct evepoll));
 168                 if (fds == NULL) {
 169                         event_warn("realloc");
 170                         return (-1);
 171                 }
 172                 epollop->fds = fds;
 173                 memset(fds + epollop->nfds, 0,
 174                     (nfds - epollop->nfds) * sizeof(struct evepoll));
 175                 epollop->nfds = nfds;
 176         }
 177
 178         return (0);
 179 }
 180
 181 static int
 182 epoll_dispatch(struct event_base *base, void *arg, struct timeval *tv)
 183 {
 184         struct epollop *epollop = arg;
 185         struct epoll_event *events = epollop->events;
 186         struct evepoll *evep;
 187         int i, res, timeout = -1;
 188
 189         if (tv != NULL)
 190                 timeout = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;
 191
 192         if (timeout > MAX_EPOLL_TIMEOUT_MSEC) {
 193                 /* Linux kernels can wait forever if the timeout is too big;
 194                  * see comment on MAX_EPOLL_TIMEOUT_MSEC. */
 195                 timeout = MAX_EPOLL_TIMEOUT_MSEC;
 196         }
 197
 198         res = epoll_wait(epollop->epfd, events, epollop->nevents, timeout);
 199
 200         if (res == -1) {
 201                 if (errno != EINTR) {
 202                         event_warn("epoll_wait");
 203                         return (-1);
 204                 }
 205
 206                 evsignal_process(base);
 207                 return (0);
 208         } else if (base->sig.evsignal_caught) {
 209                 evsignal_process(base);
 210         }
 211
 212         event_debug(("%s: epoll_wait reports %d", __func__, res));
 213
 214         for (i = 0; i < res; i++) {
 215                 int what = events[i].events;
 216                 struct event *evread = NULL, *evwrite = NULL;
 217                 int fd = events[i].data.fd;
 218
 219                 if (fd < 0 || fd >= epollop->nfds)
 220                         continue;
 221                 evep = &epollop->fds[fd];
 222
 223                 if (what & (EPOLLHUP|EPOLLERR)) {
 224                         evread = evep->evread;
 225                         evwrite = evep->evwrite;
 226                 } else {
 227                         if (what & EPOLLIN) {
 228                                 evread = evep->evread;
 229                         }
 230
 231                         if (what & EPOLLOUT) {
 232                                 evwrite = evep->evwrite;
 233                         }
 234                 }
 235
 236                 if (!(evread||evwrite))
 237                         continue;
 238
 239                 if (evread != NULL)
 240                         event_active(evread, EV_READ, 1);
 241                 if (evwrite != NULL)
 242                         event_active(evwrite, EV_WRITE, 1);
 243         }
 244
 245         if (res == epollop->nevents && epollop->nevents < MAX_NEVENTS) {
 246                 /* We used all of the event space this time.  We should
 247                    be ready for more events next time. */
 248                 int new_nevents = epollop->nevents * 2;
 249                 struct epoll_event *new_events;
 250
 251                 new_events = realloc(epollop->events,
 252                     new_nevents * sizeof(struct epoll_event));
 253                 if (new_events) {
 254                         epollop->events = new_events;
 255                         epollop->nevents = new_nevents;
 256                 }
 257         }
 258
 259         return (0);
 260 }
 261
 262
 263 static int
 264 epoll_add(void *arg, struct event *ev)
 265 {
 266         struct epollop *epollop = arg;
 267         struct epoll_event epev = {0, {0}};
 268         struct evepoll *evep;
 269         int fd, op, events;
 270
 271         if (ev->ev_events & EV_SIGNAL)
 272                 return (evsignal_add(ev));
 273
 274         fd = ev->ev_fd;
 275         if (fd >= epollop->nfds) {
 276                 /* Extent the file descriptor array as necessary */
 277                 if (epoll_recalc(ev->ev_base, epollop, fd) == -1)
 278                         return (-1);
 279         }
 280         evep = &epollop->fds[fd];
 281         op = EPOLL_CTL_ADD;
 282         events = 0;
 283         if (evep->evread != NULL) {
 284                 events |= EPOLLIN;
 285                 op = EPOLL_CTL_MOD;
 286         }
 287         if (evep->evwrite != NULL) {
 288                 events |= EPOLLOUT;
 289                 op = EPOLL_CTL_MOD;
 290         }
 291
 292         if (ev->ev_events & EV_READ)
 293                 events |= EPOLLIN;
 294         if (ev->ev_events & EV_WRITE)
 295                 events |= EPOLLOUT;
 296
 297         epev.data.fd = fd;
 298         epev.events = events;
 299         if (epoll_ctl(epollop->epfd, op, ev->ev_fd, &epev) == -1)
 300                         return (-1);
 301
 302         /* Update events responsible */
 303         if (ev->ev_events & EV_READ)
 304                 evep->evread = ev;
 305         if (ev->ev_events & EV_WRITE)
 306                 evep->evwrite = ev;
 307
 308         return (0);
 309 }
 310
 311 static int
 312 epoll_del(void *arg, struct event *ev)
 313 {
 314         struct epollop *epollop = arg;
 315         struct epoll_event epev = {0, {0}};
 316         struct evepoll *evep;
 317         int fd, events, op;
 318         int needwritedelete = 1, needreaddelete = 1;
 319
 320         if (ev->ev_events & EV_SIGNAL)
 321                 return (evsignal_del(ev));
 322
 323         fd = ev->ev_fd;
 324         if (fd >= epollop->nfds)
 325                 return (0);
 326         evep = &epollop->fds[fd];
 327
 328         op = EPOLL_CTL_DEL;
 329         events = 0;
 330
 331         if (ev->ev_events & EV_READ)
 332                 events |= EPOLLIN;
 333         if (ev->ev_events & EV_WRITE)
 334                 events |= EPOLLOUT;
 335
 336         if ((events & (EPOLLIN|EPOLLOUT)) != (EPOLLIN|EPOLLOUT)) {
 337                 if ((events & EPOLLIN) && evep->evwrite != NULL) {
 338                         needwritedelete = 0;
 339                         events = EPOLLOUT;
 340                         op = EPOLL_CTL_MOD;
 341                 } else if ((events & EPOLLOUT) && evep->evread != NULL) {
 342                         needreaddelete = 0;
 343                         events = EPOLLIN;
 344                         op = EPOLL_CTL_MOD;
 345                 }
 346         }
 347
 348         epev.events = events;
 349         epev.data.fd = fd;
 350
 351         if (needreaddelete)
 352                 evep->evread = NULL;
 353         if (needwritedelete)
 354                 evep->evwrite = NULL;
 355
 356         if (epoll_ctl(epollop->epfd, op, fd, &epev) == -1)
 357                 return (-1);
 358
 359         return (0);
 360 }
 361
 362 static void
 363 epoll_dealloc(struct event_base *base, void *arg)
 364 {
 365         struct epollop *epollop = arg;
 366
 367         evsignal_dealloc(base);
 368         if (epollop->fds)
 369                 free(epollop->fds);
 370         if (epollop->events)
 371                 free(epollop->events);
 372         if (epollop->epfd >= 0)
 373                 close(epollop->epfd);
 374
 375         memset(epollop, 0, sizeof(struct epollop));
 376         free(epollop);
 377 }