external/bsd/libevent/dist/poll.c

   1 /*      $NetBSD: poll.c,v 1.1.1.2 2013/04/11 16:43:26 christos Exp $    */
   2 /*      $OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
   3
   4 /*
   5  * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
   6  * Copyright 2007-2012 Niels Provos and Nick Mathewson
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. The name of the author may not be used to endorse or promote products
  17  *    derived from this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30 #include "event2/event-config.h"
  31 #include <sys/cdefs.h>
  32 __RCSID("$NetBSD: poll.c,v 1.1.1.2 2013/04/11 16:43:26 christos Exp $");
  33
  34 #include <sys/types.h>
  35 #ifdef _EVENT_HAVE_SYS_TIME_H
  36 #include <sys/time.h>
  37 #endif
  38 #include <sys/queue.h>
  39 #include <poll.h>
  40 #include <signal.h>
  41 #include <limits.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <unistd.h>
  46 #include <errno.h>
  47
  48 #include "event-internal.h"
  49 #include "evsignal-internal.h"
  50 #include "log-internal.h"
  51 #include "evmap-internal.h"
  52 #include "event2/thread.h"
  53 #include "evthread-internal.h"
  54
  55 struct pollidx {
  56         int idxplus1;
  57 };
  58
  59 struct pollop {
  60         int event_count;                /* Highest number alloc */
  61         int nfds;                       /* Highest number used */
  62         int realloc_copy;               /* True iff we must realloc
  63                                          * event_set_copy */
  64         struct pollfd *event_set;
  65         struct pollfd *event_set_copy;
  66 };
  67
  68 static void *poll_init(struct event_base *);
  69 static int poll_add(struct event_base *, int, short old, short events, void *_idx);
  70 static int poll_del(struct event_base *, int, short old, short events, void *_idx);
  71 static int poll_dispatch(struct event_base *, struct timeval *);
  72 static void poll_dealloc(struct event_base *);
  73
  74 const struct eventop pollops = {
  75         "poll",
  76         poll_init,
  77         poll_add,
  78         poll_del,
  79         poll_dispatch,
  80         poll_dealloc,
  81         0, /* doesn't need_reinit */
  82         EV_FEATURE_FDS,
  83         sizeof(struct pollidx),
  84 };
  85
  86 static void *
  87 poll_init(struct event_base *base)
  88 {
  89         struct pollop *pollop;
  90
  91         if (!(pollop = mm_calloc(1, sizeof(struct pollop))))
  92                 return (NULL);
  93
  94         evsig_init(base);
  95
  96         return (pollop);
  97 }
  98
  99 #ifdef CHECK_INVARIANTS
 100 static void
 101 poll_check_ok(struct pollop *pop)
 102 {
 103         int i, idx;
 104         struct event *ev;
 105
 106         for (i = 0; i < pop->fd_count; ++i) {
 107                 idx = pop->idxplus1_by_fd[i]-1;
 108                 if (idx < 0)
 109                         continue;
 110                 EVUTIL_ASSERT(pop->event_set[idx].fd == i);
 111         }
 112         for (i = 0; i < pop->nfds; ++i) {
 113                 struct pollfd *pfd = &pop->event_set[i];
 114                 EVUTIL_ASSERT(pop->idxplus1_by_fd[pfd->fd] == i+1);
 115         }
 116 }
 117 #else
 118 #define poll_check_ok(pop)
 119 #endif
 120
 121 static int
 122 poll_dispatch(struct event_base *base, struct timeval *tv)
 123 {
 124         int res, i, j, nfds;
 125         long msec = -1;
 126         struct pollop *pop = base->evbase;
 127         struct pollfd *event_set;
 128
 129         poll_check_ok(pop);
 130
 131         nfds = pop->nfds;
 132
 133 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
 134         if (base->th_base_lock) {
 135                 /* If we're using this backend in a multithreaded setting,
 136                  * then we need to work on a copy of event_set, so that we can
 137                  * let other threads modify the main event_set while we're
 138                  * polling. If we're not multithreaded, then we'll skip the
 139                  * copy step here to save memory and time. */
 140                 if (pop->realloc_copy) {
 141                         struct pollfd *tmp = mm_realloc(pop->event_set_copy,
 142                             pop->event_count * sizeof(struct pollfd));
 143                         if (tmp == NULL) {
 144                                 event_warn("realloc");
 145                                 return -1;
 146                         }
 147                         pop->event_set_copy = tmp;
 148                         pop->realloc_copy = 0;
 149                 }
 150                 memcpy(pop->event_set_copy, pop->event_set,
 151                     sizeof(struct pollfd)*nfds);
 152                 event_set = pop->event_set_copy;
 153         } else {
 154                 event_set = pop->event_set;
 155         }
 156 #else
 157         event_set = pop->event_set;
 158 #endif
 159
 160         if (tv != NULL) {
 161                 msec = evutil_tv_to_msec(tv);
 162                 if (msec < 0 || msec > INT_MAX)
 163                         msec = INT_MAX;
 164         }
 165
 166         EVBASE_RELEASE_LOCK(base, th_base_lock);
 167
 168         res = poll(event_set, nfds, msec);
 169
 170         EVBASE_ACQUIRE_LOCK(base, th_base_lock);
 171
 172         if (res == -1) {
 173                 if (errno != EINTR) {
 174                         event_warn("poll");
 175                         return (-1);
 176                 }
 177
 178                 return (0);
 179         }
 180
 181         event_debug(("%s: poll reports %d", __func__, res));
 182
 183         if (res == 0 || nfds == 0)
 184                 return (0);
 185
 186         i = random() % nfds;
 187         for (j = 0; j < nfds; j++) {
 188                 int what;
 189                 if (++i == nfds)
 190                         i = 0;
 191                 what = event_set[i].revents;
 192                 if (!what)
 193                         continue;
 194
 195                 res = 0;
 196
 197                 /* If the file gets closed notify */
 198                 if (what & (POLLHUP|POLLERR))
 199                         what |= POLLIN|POLLOUT;
 200                 if (what & POLLIN)
 201                         res |= EV_READ;
 202                 if (what & POLLOUT)
 203                         res |= EV_WRITE;
 204                 if (res == 0)
 205                         continue;
 206
 207                 evmap_io_active(base, event_set[i].fd, res);
 208         }
 209
 210         return (0);
 211 }
 212
 213 static int
 214 poll_add(struct event_base *base, int fd, short old, short events, void *_idx)
 215 {
 216         struct pollop *pop = base->evbase;
 217         struct pollfd *pfd = NULL;
 218         struct pollidx *idx = _idx;
 219         int i;
 220
 221         EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
 222         if (!(events & (EV_READ|EV_WRITE)))
 223                 return (0);
 224
 225         poll_check_ok(pop);
 226         if (pop->nfds + 1 >= pop->event_count) {
 227                 struct pollfd *tmp_event_set;
 228                 int tmp_event_count;
 229
 230                 if (pop->event_count < 32)
 231                         tmp_event_count = 32;
 232                 else
 233                         tmp_event_count = pop->event_count * 2;
 234
 235                 /* We need more file descriptors */
 236                 tmp_event_set = mm_realloc(pop->event_set,
 237                                  tmp_event_count * sizeof(struct pollfd));
 238                 if (tmp_event_set == NULL) {
 239                         event_warn("realloc");
 240                         return (-1);
 241                 }
 242                 pop->event_set = tmp_event_set;
 243
 244                 pop->event_count = tmp_event_count;
 245                 pop->realloc_copy = 1;
 246         }
 247
 248         i = idx->idxplus1 - 1;
 249
 250         if (i >= 0) {
 251                 pfd = &pop->event_set[i];
 252         } else {
 253                 i = pop->nfds++;
 254                 pfd = &pop->event_set[i];
 255                 pfd->events = 0;
 256                 pfd->fd = fd;
 257                 idx->idxplus1 = i + 1;
 258         }
 259
 260         pfd->revents = 0;
 261         if (events & EV_WRITE)
 262                 pfd->events |= POLLOUT;
 263         if (events & EV_READ)
 264                 pfd->events |= POLLIN;
 265         poll_check_ok(pop);
 266
 267         return (0);
 268 }
 269
 270 /*
 271  * Nothing to be done here.
 272  */
 273
 274 static int
 275 poll_del(struct event_base *base, int fd, short old, short events, void *_idx)
 276 {
 277         struct pollop *pop = base->evbase;
 278         struct pollfd *pfd = NULL;
 279         struct pollidx *idx = _idx;
 280         int i;
 281
 282         EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
 283         if (!(events & (EV_READ|EV_WRITE)))
 284                 return (0);
 285
 286         poll_check_ok(pop);
 287         i = idx->idxplus1 - 1;
 288         if (i < 0)
 289                 return (-1);
 290
 291         /* Do we still want to read or write? */
 292         pfd = &pop->event_set[i];
 293         if (events & EV_READ)
 294                 pfd->events &= ~POLLIN;
 295         if (events & EV_WRITE)
 296                 pfd->events &= ~POLLOUT;
 297         poll_check_ok(pop);
 298         if (pfd->events)
 299                 /* Another event cares about that fd. */
 300                 return (0);
 301
 302         /* Okay, so we aren't interested in that fd anymore. */
 303         idx->idxplus1 = 0;
 304
 305         --pop->nfds;
 306         if (i != pop->nfds) {
 307                 /*
 308                  * Shift the last pollfd down into the now-unoccupied
 309                  * position.
 310                  */
 311                 memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],
 312                        sizeof(struct pollfd));
 313                 idx = evmap_io_get_fdinfo(&base->io, pop->event_set[i].fd);
 314                 EVUTIL_ASSERT(idx);
 315                 EVUTIL_ASSERT(idx->idxplus1 == pop->nfds + 1);
 316                 idx->idxplus1 = i + 1;
 317         }
 318
 319         poll_check_ok(pop);
 320         return (0);
 321 }
 322
 323 static void
 324 poll_dealloc(struct event_base *base)
 325 {
 326         struct pollop *pop = base->evbase;
 327
 328         evsig_dealloc(base);
 329         if (pop->event_set)
 330                 mm_free(pop->event_set);
 331         if (pop->event_set_copy)
 332                 mm_free(pop->event_set_copy);
 333
 334         memset(pop, 0, sizeof(struct pollop));
 335         mm_free(pop);
 336 }