external/bsd/libevent/dist/poll.c

   1 /*      $NetBSD$        */
   2 /*      $OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
   3
   4 /*
   5  * Copyright 2000-2003 Niels Provos <provos@citi.umich.edu>
   6  * All rights reserved.
   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 #ifdef HAVE_CONFIG_H
  31 #include "config.h"
  32 #endif
  33
  34 #include <sys/types.h>
  35 #ifdef HAVE_SYS_TIME_H
  36 #include <sys/time.h>
  37 #else
  38 #include <sys/_time.h>
  39 #endif
  40 #include <sys/queue.h>
  41 #include <poll.h>
  42 #include <signal.h>
  43 #include <stdio.h>
  44 #include <stdlib.h>
  45 #include <string.h>
  46 #include <unistd.h>
  47 #include <errno.h>
  48 #ifdef CHECK_INVARIANTS
  49 #include <assert.h>
  50 #endif
  51
  52 #include "event.h"
  53 #include "event-internal.h"
  54 #include "evsignal.h"
  55 #include "log.h"
  56
  57 struct pollop {
  58         int event_count;                /* Highest number alloc */
  59         int nfds;                       /* Size of event_* */
  60         int fd_count;                   /* Size of idxplus1_by_fd */
  61         struct pollfd *event_set;
  62         struct event **event_r_back;
  63         struct event **event_w_back;
  64         int *idxplus1_by_fd; /* Index into event_set by fd; we add 1 so
  65                               * that 0 (which is easy to memset) can mean
  66                               * "no entry." */
  67 };
  68
  69 static void *poll_init  (struct event_base *);
  70 static int poll_add             (void *, struct event *);
  71 static int poll_del             (void *, struct event *);
  72 static int poll_dispatch        (struct event_base *, void *, struct timeval *);
  73 static void poll_dealloc        (struct event_base *, void *);
  74
  75 const struct eventop pollops = {
  76         "poll",
  77         poll_init,
  78         poll_add,
  79         poll_del,
  80         poll_dispatch,
  81         poll_dealloc,
  82     0
  83 };
  84
  85 static void *
  86 poll_init(struct event_base *base)
  87 {
  88         struct pollop *pollop;
  89
  90         /* Disable poll when this environment variable is set */
  91         if (getenv("EVENT_NOPOLL"))
  92                 return (NULL);
  93
  94         if (!(pollop = calloc(1, sizeof(struct pollop))))
  95                 return (NULL);
  96
  97         evsignal_init(base);
  98
  99         return (pollop);
 100 }
 101
 102 #ifdef CHECK_INVARIANTS
 103 static void
 104 poll_check_ok(struct pollop *pop)
 105 {
 106         int i, idx;
 107         struct event *ev;
 108
 109         for (i = 0; i < pop->fd_count; ++i) {
 110                 idx = pop->idxplus1_by_fd[i]-1;
 111                 if (idx < 0)
 112                         continue;
 113                 assert(pop->event_set[idx].fd == i);
 114                 if (pop->event_set[idx].events & POLLIN) {
 115                         ev = pop->event_r_back[idx];
 116                         assert(ev);
 117                         assert(ev->ev_events & EV_READ);
 118                         assert(ev->ev_fd == i);
 119                 }
 120                 if (pop->event_set[idx].events & POLLOUT) {
 121                         ev = pop->event_w_back[idx];
 122                         assert(ev);
 123                         assert(ev->ev_events & EV_WRITE);
 124                         assert(ev->ev_fd == i);
 125                 }
 126         }
 127         for (i = 0; i < pop->nfds; ++i) {
 128                 struct pollfd *pfd = &pop->event_set[i];
 129                 assert(pop->idxplus1_by_fd[pfd->fd] == i+1);
 130         }
 131 }
 132 #else
 133 #define poll_check_ok(pop)
 134 #endif
 135
 136 static int
 137 poll_dispatch(struct event_base *base, void *arg, struct timeval *tv)
 138 {
 139         int res, i, j, msec = -1, nfds;
 140         struct pollop *pop = arg;
 141
 142         poll_check_ok(pop);
 143
 144         if (tv != NULL)
 145                 msec = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;
 146
 147         nfds = pop->nfds;
 148         res = poll(pop->event_set, nfds, msec);
 149
 150         if (res == -1) {
 151                 if (errno != EINTR) {
 152                         event_warn("poll");
 153                         return (-1);
 154                 }
 155
 156                 evsignal_process(base);
 157                 return (0);
 158         } else if (base->sig.evsignal_caught) {
 159                 evsignal_process(base);
 160         }
 161
 162         event_debug(("%s: poll reports %d", __func__, res));
 163
 164         if (res == 0 || nfds == 0)
 165                 return (0);
 166
 167         i = random() % nfds;
 168         for (j = 0; j < nfds; j++) {
 169                 struct event *r_ev = NULL, *w_ev = NULL;
 170                 int what;
 171                 if (++i == nfds)
 172                         i = 0;
 173                 what = pop->event_set[i].revents;
 174
 175                 if (!what)
 176                         continue;
 177
 178                 res = 0;
 179
 180                 /* If the file gets closed notify */
 181                 if (what & (POLLHUP|POLLERR))
 182                         what |= POLLIN|POLLOUT;
 183                 if (what & POLLIN) {
 184                         res |= EV_READ;
 185                         r_ev = pop->event_r_back[i];
 186                 }
 187                 if (what & POLLOUT) {
 188                         res |= EV_WRITE;
 189                         w_ev = pop->event_w_back[i];
 190                 }
 191                 if (res == 0)
 192                         continue;
 193
 194                 if (r_ev && (res & r_ev->ev_events)) {
 195                         event_active(r_ev, res & r_ev->ev_events, 1);
 196                 }
 197                 if (w_ev && w_ev != r_ev && (res & w_ev->ev_events)) {
 198                         event_active(w_ev, res & w_ev->ev_events, 1);
 199                 }
 200         }
 201
 202         return (0);
 203 }
 204
 205 static int
 206 poll_add(void *arg, struct event *ev)
 207 {
 208         struct pollop *pop = arg;
 209         struct pollfd *pfd = NULL;
 210         int i;
 211
 212         if (ev->ev_events & EV_SIGNAL)
 213                 return (evsignal_add(ev));
 214         if (!(ev->ev_events & (EV_READ|EV_WRITE)))
 215                 return (0);
 216
 217         poll_check_ok(pop);
 218         if (pop->nfds + 1 >= pop->event_count) {
 219                 struct pollfd *tmp_event_set;
 220                 struct event **tmp_event_r_back;
 221                 struct event **tmp_event_w_back;
 222                 int tmp_event_count;
 223
 224                 if (pop->event_count < 32)
 225                         tmp_event_count = 32;
 226                 else
 227                         tmp_event_count = pop->event_count * 2;
 228
 229                 /* We need more file descriptors */
 230                 tmp_event_set = realloc(pop->event_set,
 231                                  tmp_event_count * sizeof(struct pollfd));
 232                 if (tmp_event_set == NULL) {
 233                         event_warn("realloc");
 234                         return (-1);
 235                 }
 236                 pop->event_set = tmp_event_set;
 237
 238                 tmp_event_r_back = realloc(pop->event_r_back,
 239                             tmp_event_count * sizeof(struct event *));
 240                 if (tmp_event_r_back == NULL) {
 241                         /* event_set overallocated; that's okay. */
 242                         event_warn("realloc");
 243                         return (-1);
 244                 }
 245                 pop->event_r_back = tmp_event_r_back;
 246
 247                 tmp_event_w_back = realloc(pop->event_w_back,
 248                             tmp_event_count * sizeof(struct event *));
 249                 if (tmp_event_w_back == NULL) {
 250                         /* event_set and event_r_back overallocated; that's
 251                          * okay. */
 252                         event_warn("realloc");
 253                         return (-1);
 254                 }
 255                 pop->event_w_back = tmp_event_w_back;
 256
 257                 pop->event_count = tmp_event_count;
 258         }
 259         if (ev->ev_fd >= pop->fd_count) {
 260                 int *tmp_idxplus1_by_fd;
 261                 int new_count;
 262                 if (pop->fd_count < 32)
 263                         new_count = 32;
 264                 else
 265                         new_count = pop->fd_count * 2;
 266                 while (new_count <= ev->ev_fd)
 267                         new_count *= 2;
 268                 tmp_idxplus1_by_fd =
 269                         realloc(pop->idxplus1_by_fd, new_count * sizeof(int));
 270                 if (tmp_idxplus1_by_fd == NULL) {
 271                         event_warn("realloc");
 272                         return (-1);
 273                 }
 274                 pop->idxplus1_by_fd = tmp_idxplus1_by_fd;
 275                 memset(pop->idxplus1_by_fd + pop->fd_count,
 276                        0, sizeof(int)*(new_count - pop->fd_count));
 277                 pop->fd_count = new_count;
 278         }
 279
 280         i = pop->idxplus1_by_fd[ev->ev_fd] - 1;
 281         if (i >= 0) {
 282                 pfd = &pop->event_set[i];
 283         } else {
 284                 i = pop->nfds++;
 285                 pfd = &pop->event_set[i];
 286                 pfd->events = 0;
 287                 pfd->fd = ev->ev_fd;
 288                 pop->event_w_back[i] = pop->event_r_back[i] = NULL;
 289                 pop->idxplus1_by_fd[ev->ev_fd] = i + 1;
 290         }
 291
 292         pfd->revents = 0;
 293         if (ev->ev_events & EV_WRITE) {
 294                 pfd->events |= POLLOUT;
 295                 pop->event_w_back[i] = ev;
 296         }
 297         if (ev->ev_events & EV_READ) {
 298                 pfd->events |= POLLIN;
 299                 pop->event_r_back[i] = ev;
 300         }
 301         poll_check_ok(pop);
 302
 303         return (0);
 304 }
 305
 306 /*
 307  * Nothing to be done here.
 308  */
 309
 310 static int
 311 poll_del(void *arg, struct event *ev)
 312 {
 313         struct pollop *pop = arg;
 314         struct pollfd *pfd = NULL;
 315         int i;
 316
 317         if (ev->ev_events & EV_SIGNAL)
 318                 return (evsignal_del(ev));
 319
 320         if (!(ev->ev_events & (EV_READ|EV_WRITE)))
 321                 return (0);
 322
 323         poll_check_ok(pop);
 324         i = pop->idxplus1_by_fd[ev->ev_fd] - 1;
 325         if (i < 0)
 326                 return (-1);
 327
 328         /* Do we still want to read or write? */
 329         pfd = &pop->event_set[i];
 330         if (ev->ev_events & EV_READ) {
 331                 pfd->events &= ~POLLIN;
 332                 pop->event_r_back[i] = NULL;
 333         }
 334         if (ev->ev_events & EV_WRITE) {
 335                 pfd->events &= ~POLLOUT;
 336                 pop->event_w_back[i] = NULL;
 337         }
 338         poll_check_ok(pop);
 339         if (pfd->events)
 340                 /* Another event cares about that fd. */
 341                 return (0);
 342
 343         /* Okay, so we aren't interested in that fd anymore. */
 344         pop->idxplus1_by_fd[ev->ev_fd] = 0;
 345
 346         --pop->nfds;
 347         if (i != pop->nfds) {
 348                 /*
 349                  * Shift the last pollfd down into the now-unoccupied
 350                  * position.
 351                  */
 352                 memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],
 353                        sizeof(struct pollfd));
 354                 pop->event_r_back[i] = pop->event_r_back[pop->nfds];
 355                 pop->event_w_back[i] = pop->event_w_back[pop->nfds];
 356                 pop->idxplus1_by_fd[pop->event_set[i].fd] = i + 1;
 357         }
 358
 359         poll_check_ok(pop);
 360         return (0);
 361 }
 362
 363 static void
 364 poll_dealloc(struct event_base *base, void *arg)
 365 {
 366         struct pollop *pop = arg;
 367
 368         evsignal_dealloc(base);
 369         if (pop->event_set)
 370                 free(pop->event_set);
 371         if (pop->event_r_back)
 372                 free(pop->event_r_back);
 373         if (pop->event_w_back)
 374                 free(pop->event_w_back);
 375         if (pop->idxplus1_by_fd)
 376                 free(pop->idxplus1_by_fd);
 377
 378         memset(pop, 0, sizeof(struct pollop));
 379         free(pop);
 380 }