third_party/libevent/poll.c

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