contrib/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/_time.h>
  38 #endif
  39 #include <sys/queue.h>
  40 #include <sys/tree.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 void *poll_init (struct event_base *);
  70 int poll_add            (void *, struct event *);
  71 int poll_del            (void *, struct event *);
  72 int poll_recalc         (struct event_base *, void *, int);
  73 int poll_dispatch       (struct event_base *, void *, struct timeval *);
  74 void poll_dealloc       (struct event_base *, void *);
  75
  76 const struct eventop pollops = {
  77         "poll",
  78         poll_init,
  79         poll_add,
  80         poll_del,
  81         poll_recalc,
  82         poll_dispatch,
  83         poll_dealloc
  84 };
  85
  86 void *
  87 poll_init(struct event_base *base)
  88 {
  89         struct pollop *pollop;
  90
  91         /* Disable poll when this environment variable is set */
  92         if (getenv("EVENT_NOPOLL"))
  93                 return (NULL);
  94
  95         if (!(pollop = calloc(1, sizeof(struct pollop))))
  96                 return (NULL);
  97
  98         evsignal_init(base);
  99
 100         return (pollop);
 101 }
 102
 103 /*
 104  * Called with the highest fd that we know about.  If it is 0, completely
 105  * recalculate everything.
 106  */
 107
 108 int
 109 poll_recalc(struct event_base *base, void *arg, int max)
 110 {
 111         return (0);
 112 }
 113
 114 #ifdef CHECK_INVARIANTS
 115 static void
 116 poll_check_ok(struct pollop *pop)
 117 {
 118         int i, idx;
 119         struct event *ev;
 120
 121         for (i = 0; i < pop->fd_count; ++i) {
 122                 idx = pop->idxplus1_by_fd[i]-1;
 123                 if (idx < 0)
 124                         continue;
 125                 assert(pop->event_set[idx].fd == i);
 126                 if (pop->event_set[idx].events & POLLIN) {
 127                         ev = pop->event_r_back[idx];
 128                         assert(ev);
 129                         assert(ev->ev_events & EV_READ);
 130                         assert(ev->ev_fd == i);
 131                 }
 132                 if (pop->event_set[idx].events & POLLOUT) {
 133                         ev = pop->event_w_back[idx];
 134                         assert(ev);
 135                         assert(ev->ev_events & EV_WRITE);
 136                         assert(ev->ev_fd == i);
 137                 }
 138         }
 139         for (i = 0; i < pop->nfds; ++i) {
 140                 struct pollfd *pfd = &pop->event_set[i];
 141                 assert(pop->idxplus1_by_fd[pfd->fd] == i+1);
 142         }
 143 }
 144 #else
 145 #define poll_check_ok(pop)
 146 #endif
 147
 148 int
 149 poll_dispatch(struct event_base *base, void *arg, struct timeval *tv)
 150 {
 151         int res, i, msec = -1, nfds;
 152         struct pollop *pop = arg;
 153
 154         poll_check_ok(pop);
 155
 156         if (tv != NULL)
 157                 msec = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;
 158
 159         nfds = pop->nfds;
 160         res = poll(pop->event_set, nfds, msec);
 161
 162         if (res == -1) {
 163                 if (errno != EINTR) {
 164                         event_warn("poll");
 165                         return (-1);
 166                 }
 167
 168                 evsignal_process(base);
 169                 return (0);
 170         } else if (base->sig.evsignal_caught) {
 171                 evsignal_process(base);
 172         }
 173
 174         event_debug(("%s: poll reports %d", __func__, res));
 175
 176         if (res == 0)
 177                 return (0);
 178
 179         for (i = 0; i < nfds; i++) {
 180                 int what = pop->event_set[i].revents;
 181                 struct event *r_ev = NULL, *w_ev = NULL;
 182                 if (!what)
 183                         continue;
 184
 185                 res = 0;
 186
 187                 /* If the file gets closed notify */
 188                 if (what & (POLLHUP|POLLERR))
 189                         what |= POLLIN|POLLOUT;
 190                 if (what & POLLIN) {
 191                         res |= EV_READ;
 192                         r_ev = pop->event_r_back[i];
 193                 }
 194                 if (what & POLLOUT) {
 195                         res |= EV_WRITE;
 196                         w_ev = pop->event_w_back[i];
 197                 }
 198                 if (res == 0)
 199                         continue;
 200
 201                 if (r_ev && (res & r_ev->ev_events)) {
 202                         if (!(r_ev->ev_events & EV_PERSIST))
 203                                 event_del(r_ev);
 204                         event_active(r_ev, res & r_ev->ev_events, 1);
 205                 }
 206                 if (w_ev && w_ev != r_ev && (res & w_ev->ev_events)) {
 207                         if (!(w_ev->ev_events & EV_PERSIST))
 208                                 event_del(w_ev);
 209                         event_active(w_ev, res & w_ev->ev_events, 1);
 210                 }
 211         }
 212
 213         return (0);
 214 }
 215
 216 int
 217 poll_add(void *arg, struct event *ev)
 218 {
 219         struct pollop *pop = arg;
 220         struct pollfd *pfd = NULL;
 221         int i;
 222
 223         if (ev->ev_events & EV_SIGNAL)
 224                 return (evsignal_add(ev));
 225         if (!(ev->ev_events & (EV_READ|EV_WRITE)))
 226                 return (0);
 227
 228         poll_check_ok(pop);
 229         if (pop->nfds + 1 >= pop->event_count) {
 230                 struct pollfd *tmp_event_set;
 231                 struct event **tmp_event_r_back;
 232                 struct event **tmp_event_w_back;
 233                 int tmp_event_count;
 234
 235                 if (pop->event_count < 32)
 236                         tmp_event_count = 32;
 237                 else
 238                         tmp_event_count = pop->event_count * 2;
 239
 240                 /* We need more file descriptors */
 241                 tmp_event_set = realloc(pop->event_set,
 242                                  tmp_event_count * sizeof(struct pollfd));
 243                 if (tmp_event_set == NULL) {
 244                         event_warn("realloc");
 245                         return (-1);
 246                 }
 247                 pop->event_set = tmp_event_set;
 248
 249                 tmp_event_r_back = realloc(pop->event_r_back,
 250                             tmp_event_count * sizeof(struct event *));
 251                 if (tmp_event_r_back == NULL) {
 252                         /* event_set overallocated; that's okay. */
 253                         event_warn("realloc");
 254                         return (-1);
 255                 }
 256                 pop->event_r_back = tmp_event_r_back;
 257
 258                 tmp_event_w_back = realloc(pop->event_w_back,
 259                             tmp_event_count * sizeof(struct event *));
 260                 if (tmp_event_w_back == NULL) {
 261                         /* event_set and event_r_back overallocated; that's
 262                          * okay. */
 263                         event_warn("realloc");
 264                         return (-1);
 265                 }
 266                 pop->event_w_back = tmp_event_w_back;
 267
 268                 pop->event_count = tmp_event_count;
 269         }
 270         if (ev->ev_fd >= pop->fd_count) {
 271                 int *tmp_idxplus1_by_fd;
 272                 int new_count;
 273                 if (pop->fd_count < 32)
 274                         new_count = 32;
 275                 else
 276                         new_count = pop->fd_count * 2;
 277                 while (new_count <= ev->ev_fd)
 278                         new_count *= 2;
 279                 tmp_idxplus1_by_fd =
 280                         realloc(pop->idxplus1_by_fd, new_count * sizeof(int));
 281                 if (tmp_idxplus1_by_fd == NULL) {
 282                         event_warn("realloc");
 283                         return (-1);
 284                 }
 285                 pop->idxplus1_by_fd = tmp_idxplus1_by_fd;
 286                 memset(pop->idxplus1_by_fd + pop->fd_count,
 287                        0, sizeof(int)*(new_count - pop->fd_count));
 288                 pop->fd_count = new_count;
 289         }
 290
 291         i = pop->idxplus1_by_fd[ev->ev_fd] - 1;
 292         if (i >= 0) {
 293                 pfd = &pop->event_set[i];
 294         } else {
 295                 i = pop->nfds++;
 296                 pfd = &pop->event_set[i];
 297                 pfd->events = 0;
 298                 pfd->fd = ev->ev_fd;
 299                 pop->event_w_back[i] = pop->event_r_back[i] = NULL;
 300                 pop->idxplus1_by_fd[ev->ev_fd] = i + 1;
 301         }
 302
 303         pfd->revents = 0;
 304         if (ev->ev_events & EV_WRITE) {
 305                 pfd->events |= POLLOUT;
 306                 pop->event_w_back[i] = ev;
 307         }
 308         if (ev->ev_events & EV_READ) {
 309                 pfd->events |= POLLIN;
 310                 pop->event_r_back[i] = ev;
 311         }
 312         poll_check_ok(pop);
 313
 314         return (0);
 315 }
 316
 317 /*
 318  * Nothing to be done here.
 319  */
 320
 321 int
 322 poll_del(void *arg, struct event *ev)
 323 {
 324         struct pollop *pop = arg;
 325         struct pollfd *pfd = NULL;
 326         int i;
 327
 328         if (ev->ev_events & EV_SIGNAL)
 329                 return (evsignal_del(ev));
 330
 331         if (!(ev->ev_events & (EV_READ|EV_WRITE)))
 332                 return (0);
 333
 334         poll_check_ok(pop);
 335         i = pop->idxplus1_by_fd[ev->ev_fd] - 1;
 336         if (i < 0)
 337                 return (-1);
 338
 339         /* Do we still want to read or write? */
 340         pfd = &pop->event_set[i];
 341         if (ev->ev_events & EV_READ) {
 342                 pfd->events &= ~POLLIN;
 343                 pop->event_r_back[i] = NULL;
 344         }
 345         if (ev->ev_events & EV_WRITE) {
 346                 pfd->events &= ~POLLOUT;
 347                 pop->event_w_back[i] = NULL;
 348         }
 349         poll_check_ok(pop);
 350         if (pfd->events)
 351                 /* Another event cares about that fd. */
 352                 return (0);
 353
 354         /* Okay, so we aren't interested in that fd anymore. */
 355         pop->idxplus1_by_fd[ev->ev_fd] = 0;
 356
 357         --pop->nfds;
 358         if (i != pop->nfds) {
 359                 /*
 360                  * Shift the last pollfd down into the now-unoccupied
 361                  * position.
 362                  */
 363                 memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],
 364                        sizeof(struct pollfd));
 365                 pop->event_r_back[i] = pop->event_r_back[pop->nfds];
 366                 pop->event_w_back[i] = pop->event_w_back[pop->nfds];
 367                 pop->idxplus1_by_fd[pop->event_set[i].fd] = i + 1;
 368         }
 369
 370         poll_check_ok(pop);
 371         return (0);
 372 }
 373
 374 void
 375 poll_dealloc(struct event_base *base, void *arg)
 376 {
 377         struct pollop *pop = arg;
 378
 379         evsignal_dealloc(base);
 380         if (pop->event_set)
 381                 free(pop->event_set);
 382         if (pop->event_r_back)
 383                 free(pop->event_r_back);
 384         if (pop->event_w_back)
 385                 free(pop->event_w_back);
 386         if (pop->idxplus1_by_fd)
 387                 free(pop->idxplus1_by_fd);
 388
 389         memset(pop, 0, sizeof(struct pollop));
 390         free(pop);
 391 }