release/src-rt-6.x.4708/router/libevent/poll.c

   1 /*      $OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
   2
   3 /*
   4  * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
   5  * Copyright 2007-2012 Niels Provos and Nick Mathewson
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. The name of the author may not be used to endorse or promote products
  16  *    derived from this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29 #include "event2/event-config.h"
  30
  31 #include <sys/types.h>
  32 #ifdef _EVENT_HAVE_SYS_TIME_H
  33 #include <sys/time.h>
  34 #endif
  35 #include <sys/queue.h>
  36 #include <poll.h>
  37 #include <signal.h>
  38 #include <limits.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42 #include <unistd.h>
  43 #include <errno.h>
  44
  45 #include "event-internal.h"
  46 #include "evsignal-internal.h"
  47 #include "log-internal.h"
  48 #include "evmap-internal.h"
  49 #include "event2/thread.h"
  50 #include "evthread-internal.h"
  51
  52 struct pollidx {
  53         int idxplus1;
  54 };
  55
  56 struct pollop {
  57         int event_count;                /* Highest number alloc */
  58         int nfds;                       /* Highest number used */
  59         int realloc_copy;               /* True iff we must realloc
  60                                          * event_set_copy */
  61         struct pollfd *event_set;
  62         struct pollfd *event_set_copy;
  63 };
  64
  65 static void *poll_init(struct event_base *);
  66 static int poll_add(struct event_base *, int, short old, short events, void *_idx);
  67 static int poll_del(struct event_base *, int, short old, short events, void *_idx);
  68 static int poll_dispatch(struct event_base *, struct timeval *);
  69 static void poll_dealloc(struct event_base *);
  70
  71 const struct eventop pollops = {
  72         "poll",
  73         poll_init,
  74         poll_add,
  75         poll_del,
  76         poll_dispatch,
  77         poll_dealloc,
  78         0, /* doesn't need_reinit */
  79         EV_FEATURE_FDS,
  80         sizeof(struct pollidx),
  81 };
  82
  83 static void *
  84 poll_init(struct event_base *base)
  85 {
  86         struct pollop *pollop;
  87
  88         if (!(pollop = mm_calloc(1, sizeof(struct pollop))))
  89                 return (NULL);
  90
  91         evsig_init(base);
  92
  93         return (pollop);
  94 }
  95
  96 #ifdef CHECK_INVARIANTS
  97 static void
  98 poll_check_ok(struct pollop *pop)
  99 {
 100         int i, idx;
 101         struct event *ev;
 102
 103         for (i = 0; i < pop->fd_count; ++i) {
 104                 idx = pop->idxplus1_by_fd[i]-1;
 105                 if (idx < 0)
 106                         continue;
 107                 EVUTIL_ASSERT(pop->event_set[idx].fd == i);
 108         }
 109         for (i = 0; i < pop->nfds; ++i) {
 110                 struct pollfd *pfd = &pop->event_set[i];
 111                 EVUTIL_ASSERT(pop->idxplus1_by_fd[pfd->fd] == i+1);
 112         }
 113 }
 114 #else
 115 #define poll_check_ok(pop)
 116 #endif
 117
 118 static int
 119 poll_dispatch(struct event_base *base, struct timeval *tv)
 120 {
 121         int res, i, j, nfds;
 122         long msec = -1;
 123         struct pollop *pop = base->evbase;
 124         struct pollfd *event_set;
 125
 126         poll_check_ok(pop);
 127
 128         nfds = pop->nfds;
 129
 130 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
 131         if (base->th_base_lock) {
 132                 /* If we're using this backend in a multithreaded setting,
 133                  * then we need to work on a copy of event_set, so that we can
 134                  * let other threads modify the main event_set while we're
 135                  * polling. If we're not multithreaded, then we'll skip the
 136                  * copy step here to save memory and time. */
 137                 if (pop->realloc_copy) {
 138                         struct pollfd *tmp = mm_realloc(pop->event_set_copy,
 139                             pop->event_count * sizeof(struct pollfd));
 140                         if (tmp == NULL) {
 141                                 event_warn("realloc");
 142                                 return -1;
 143                         }
 144                         pop->event_set_copy = tmp;
 145                         pop->realloc_copy = 0;
 146                 }
 147                 memcpy(pop->event_set_copy, pop->event_set,
 148                     sizeof(struct pollfd)*nfds);
 149                 event_set = pop->event_set_copy;
 150         } else {
 151                 event_set = pop->event_set;
 152         }
 153 #else
 154         event_set = pop->event_set;
 155 #endif
 156
 157         if (tv != NULL) {
 158                 msec = evutil_tv_to_msec(tv);
 159                 if (msec < 0 || msec > INT_MAX)
 160                         msec = INT_MAX;
 161         }
 162
 163         EVBASE_RELEASE_LOCK(base, th_base_lock);
 164
 165         res = poll(event_set, nfds, msec);
 166
 167         EVBASE_ACQUIRE_LOCK(base, th_base_lock);
 168
 169         if (res == -1) {
 170                 if (errno != EINTR) {
 171                         event_warn("poll");
 172                         return (-1);
 173                 }
 174
 175                 return (0);
 176         }
 177
 178         event_debug(("%s: poll reports %d", __func__, res));
 179
 180         if (res == 0 || nfds == 0)
 181                 return (0);
 182
 183         i = random() % nfds;
 184         for (j = 0; j < nfds; j++) {
 185                 int what;
 186                 if (++i == nfds)
 187                         i = 0;
 188                 what = event_set[i].revents;
 189                 if (!what)
 190                         continue;
 191
 192                 res = 0;
 193
 194                 /* If the file gets closed notify */
 195                 if (what & (POLLHUP|POLLERR))
 196                         what |= POLLIN|POLLOUT;
 197                 if (what & POLLIN)
 198                         res |= EV_READ;
 199                 if (what & POLLOUT)
 200                         res |= EV_WRITE;
 201                 if (res == 0)
 202                         continue;
 203
 204                 evmap_io_active(base, event_set[i].fd, res);
 205         }
 206
 207         return (0);
 208 }
 209
 210 static int
 211 poll_add(struct event_base *base, int fd, short old, short events, void *_idx)
 212 {
 213         struct pollop *pop = base->evbase;
 214         struct pollfd *pfd = NULL;
 215         struct pollidx *idx = _idx;
 216         int i;
 217
 218         EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
 219         if (!(events & (EV_READ|EV_WRITE)))
 220                 return (0);
 221
 222         poll_check_ok(pop);
 223         if (pop->nfds + 1 >= pop->event_count) {
 224                 struct pollfd *tmp_event_set;
 225                 int tmp_event_count;
 226
 227                 if (pop->event_count < 32)
 228                         tmp_event_count = 32;
 229                 else
 230                         tmp_event_count = pop->event_count * 2;
 231
 232                 /* We need more file descriptors */
 233                 tmp_event_set = mm_realloc(pop->event_set,
 234                                  tmp_event_count * sizeof(struct pollfd));
 235                 if (tmp_event_set == NULL) {
 236                         event_warn("realloc");
 237                         return (-1);
 238                 }
 239                 pop->event_set = tmp_event_set;
 240
 241                 pop->event_count = tmp_event_count;
 242                 pop->realloc_copy = 1;
 243         }
 244
 245         i = idx->idxplus1 - 1;
 246
 247         if (i >= 0) {
 248                 pfd = &pop->event_set[i];
 249         } else {
 250                 i = pop->nfds++;
 251                 pfd = &pop->event_set[i];
 252                 pfd->events = 0;
 253                 pfd->fd = fd;
 254                 idx->idxplus1 = i + 1;
 255         }
 256
 257         pfd->revents = 0;
 258         if (events & EV_WRITE)
 259                 pfd->events |= POLLOUT;
 260         if (events & EV_READ)
 261                 pfd->events |= POLLIN;
 262         poll_check_ok(pop);
 263
 264         return (0);
 265 }
 266
 267 /*
 268  * Nothing to be done here.
 269  */
 270
 271 static int
 272 poll_del(struct event_base *base, int fd, short old, short events, void *_idx)
 273 {
 274         struct pollop *pop = base->evbase;
 275         struct pollfd *pfd = NULL;
 276         struct pollidx *idx = _idx;
 277         int i;
 278
 279         EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
 280         if (!(events & (EV_READ|EV_WRITE)))
 281                 return (0);
 282
 283         poll_check_ok(pop);
 284         i = idx->idxplus1 - 1;
 285         if (i < 0)
 286                 return (-1);
 287
 288         /* Do we still want to read or write? */
 289         pfd = &pop->event_set[i];
 290         if (events & EV_READ)
 291                 pfd->events &= ~POLLIN;
 292         if (events & EV_WRITE)
 293                 pfd->events &= ~POLLOUT;
 294         poll_check_ok(pop);
 295         if (pfd->events)
 296                 /* Another event cares about that fd. */
 297                 return (0);
 298
 299         /* Okay, so we aren't interested in that fd anymore. */
 300         idx->idxplus1 = 0;
 301
 302         --pop->nfds;
 303         if (i != pop->nfds) {
 304                 /*
 305                  * Shift the last pollfd down into the now-unoccupied
 306                  * position.
 307                  */
 308                 memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],
 309                        sizeof(struct pollfd));
 310                 idx = evmap_io_get_fdinfo(&base->io, pop->event_set[i].fd);
 311                 EVUTIL_ASSERT(idx);
 312                 EVUTIL_ASSERT(idx->idxplus1 == pop->nfds + 1);
 313                 idx->idxplus1 = i + 1;
 314         }
 315
 316         poll_check_ok(pop);
 317         return (0);
 318 }
 319
 320 static void
 321 poll_dealloc(struct event_base *base)
 322 {
 323         struct pollop *pop = base->evbase;
 324
 325         evsig_dealloc(base);
 326         if (pop->event_set)
 327                 mm_free(pop->event_set);
 328         if (pop->event_set_copy)
 329                 mm_free(pop->event_set_copy);
 330
 331         memset(pop, 0, sizeof(struct pollop));
 332         mm_free(pop);
 333 }