third_party/libevent/evport.c

   1 /*
   2  * Submitted by David Pacheco (dp.spambait@gmail.com)
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  * 3. The name of the author may not be used to endorse or promote products
  13  *    derived from this software without specific prior written permission.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY SUN MICROSYSTEMS, INC. ``AS IS'' AND ANY
  16  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  18  * DISCLAIMED. IN NO EVENT SHALL SUN MICROSYSTEMS, INC. BE LIABLE FOR ANY
  19  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  20  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  21  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  22  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  24  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 /*
  28  * Copyright (c) 2007 Sun Microsystems. All rights reserved.
  29  * Use is subject to license terms.
  30  */
  31
  32 /*
  33  * evport.c: event backend using Solaris 10 event ports. See port_create(3C).
  34  * This implementation is loosely modeled after the one used for select(2) (in
  35  * select.c).
  36  *
  37  * The outstanding events are tracked in a data structure called evport_data.
  38  * Each entry in the ed_fds array corresponds to a file descriptor, and contains
  39  * pointers to the read and write events that correspond to that fd. (That is,
  40  * when the file is readable, the "read" event should handle it, etc.)
  41  *
  42  * evport_add and evport_del update this data structure. evport_dispatch uses it
  43  * to determine where to callback when an event occurs (which it gets from
  44  * port_getn).
  45  *
  46  * Helper functions are used: grow() grows the file descriptor array as
  47  * necessary when large fd's come in. reassociate() takes care of maintaining
  48  * the proper file-descriptor/event-port associations.
  49  *
  50  * As in the select(2) implementation, signals are handled by evsignal.
  51  */
  52
  53 #ifdef HAVE_CONFIG_H
  54 #include "config.h"
  55 #endif
  56
  57 #include <sys/time.h>
  58 #include <assert.h>
  59 #include <sys/queue.h>
  60 #include <errno.h>
  61 #include <poll.h>
  62 #include <port.h>
  63 #include <signal.h>
  64 #include <stdio.h>
  65 #include <stdlib.h>
  66 #include <string.h>
  67 #include <time.h>
  68 #include <unistd.h>
  69 #ifdef CHECK_INVARIANTS
  70 #include <assert.h>
  71 #endif
  72
  73 #include "event.h"
  74 #include "event-internal.h"
  75 #include "log.h"
  76 #include "evsignal.h"
  77
  78
  79 /*
  80  * Default value for ed_nevents, which is the maximum file descriptor number we
  81  * can handle. If an event comes in for a file descriptor F > nevents, we will
  82  * grow the array of file descriptors, doubling its size.
  83  */
  84 #define DEFAULT_NFDS    16
  85
  86
  87 /*
  88  * EVENTS_PER_GETN is the maximum number of events to retrieve from port_getn on
  89  * any particular call. You can speed things up by increasing this, but it will
  90  * (obviously) require more memory.
  91  */
  92 #define EVENTS_PER_GETN 8
  93
  94 /*
  95  * Per-file-descriptor information about what events we're subscribed to. These
  96  * fields are NULL if no event is subscribed to either of them.
  97  */
  98
  99 struct fd_info {
 100         struct event* fdi_revt; /* the event responsible for the "read"  */
 101         struct event* fdi_wevt; /* the event responsible for the "write" */
 102 };
 103
 104 #define FDI_HAS_READ(fdi)  ((fdi)->fdi_revt != NULL)
 105 #define FDI_HAS_WRITE(fdi) ((fdi)->fdi_wevt != NULL)
 106 #define FDI_HAS_EVENTS(fdi) (FDI_HAS_READ(fdi) || FDI_HAS_WRITE(fdi))
 107 #define FDI_TO_SYSEVENTS(fdi) (FDI_HAS_READ(fdi) ? POLLIN : 0) | \
 108     (FDI_HAS_WRITE(fdi) ? POLLOUT : 0)
 109
 110 struct evport_data {
 111         int             ed_port;        /* event port for system events  */
 112         int             ed_nevents;     /* number of allocated fdi's     */
 113         struct fd_info *ed_fds;         /* allocated fdi table           */
 114         /* fdi's that we need to reassoc */
 115         int ed_pending[EVENTS_PER_GETN]; /* fd's with pending events */
 116 };
 117
 118 static void*    evport_init     (struct event_base *);
 119 static int      evport_add      (void *, struct event *);
 120 static int      evport_del      (void *, struct event *);
 121 static int      evport_dispatch (struct event_base *, void *, struct timeval *);
 122 static void     evport_dealloc  (struct event_base *, void *);
 123
 124 const struct eventop evportops = {
 125         "evport",
 126         evport_init,
 127         evport_add,
 128         evport_del,
 129         evport_dispatch,
 130         evport_dealloc,
 131         1 /* need reinit */
 132 };
 133
 134 /*
 135  * Initialize the event port implementation.
 136  */
 137
 138 static void*
 139 evport_init(struct event_base *base)
 140 {
 141         struct evport_data *evpd;
 142         int i;
 143         /*
 144          * Disable event ports when this environment variable is set
 145          */
 146         if (evutil_getenv("EVENT_NOEVPORT"))
 147                 return (NULL);
 148
 149         if (!(evpd = calloc(1, sizeof(struct evport_data))))
 150                 return (NULL);
 151
 152         if ((evpd->ed_port = port_create()) == -1) {
 153                 free(evpd);
 154                 return (NULL);
 155         }
 156
 157         /*
 158          * Initialize file descriptor structure
 159          */
 160         evpd->ed_fds = calloc(DEFAULT_NFDS, sizeof(struct fd_info));
 161         if (evpd->ed_fds == NULL) {
 162                 close(evpd->ed_port);
 163                 free(evpd);
 164                 return (NULL);
 165         }
 166         evpd->ed_nevents = DEFAULT_NFDS;
 167         for (i = 0; i < EVENTS_PER_GETN; i++)
 168                 evpd->ed_pending[i] = -1;
 169
 170         evsignal_init(base);
 171
 172         return (evpd);
 173 }
 174
 175 #ifdef CHECK_INVARIANTS
 176 /*
 177  * Checks some basic properties about the evport_data structure. Because it
 178  * checks all file descriptors, this function can be expensive when the maximum
 179  * file descriptor ever used is rather large.
 180  */
 181
 182 static void
 183 check_evportop(struct evport_data *evpd)
 184 {
 185         assert(evpd);
 186         assert(evpd->ed_nevents > 0);
 187         assert(evpd->ed_port > 0);
 188         assert(evpd->ed_fds > 0);
 189
 190         /*
 191          * Verify the integrity of the fd_info struct as well as the events to
 192          * which it points (at least, that they're valid references and correct
 193          * for their position in the structure).
 194          */
 195         int i;
 196         for (i = 0; i < evpd->ed_nevents; ++i) {
 197                 struct event    *ev;
 198                 struct fd_info  *fdi;
 199
 200                 fdi = &evpd->ed_fds[i];
 201                 if ((ev = fdi->fdi_revt) != NULL) {
 202                         assert(ev->ev_fd == i);
 203                 }
 204                 if ((ev = fdi->fdi_wevt) != NULL) {
 205                         assert(ev->ev_fd == i);
 206                 }
 207         }
 208 }
 209
 210 /*
 211  * Verifies very basic integrity of a given port_event.
 212  */
 213 static void
 214 check_event(port_event_t* pevt)
 215 {
 216         /*
 217          * We've only registered for PORT_SOURCE_FD events. The only
 218          * other thing we can legitimately receive is PORT_SOURCE_ALERT,
 219          * but since we're not using port_alert either, we can assume
 220          * PORT_SOURCE_FD.
 221          */
 222         assert(pevt->portev_source == PORT_SOURCE_FD);
 223         assert(pevt->portev_user == NULL);
 224 }
 225
 226 #else
 227 #define check_evportop(epop)
 228 #define check_event(pevt)
 229 #endif /* CHECK_INVARIANTS */
 230
 231 /*
 232  * Doubles the size of the allocated file descriptor array.
 233  */
 234 static int
 235 grow(struct evport_data *epdp, int factor)
 236 {
 237         struct fd_info *tmp;
 238         int oldsize = epdp->ed_nevents;
 239         int newsize = factor * oldsize;
 240         assert(factor > 1);
 241
 242         check_evportop(epdp);
 243
 244         tmp = realloc(epdp->ed_fds, sizeof(struct fd_info) * newsize);
 245         if (NULL == tmp)
 246                 return -1;
 247         epdp->ed_fds = tmp;
 248         memset((char*) (epdp->ed_fds + oldsize), 0,
 249             (newsize - oldsize)*sizeof(struct fd_info));
 250         epdp->ed_nevents = newsize;
 251
 252         check_evportop(epdp);
 253
 254         return 0;
 255 }
 256
 257
 258 /*
 259  * (Re)associates the given file descriptor with the event port. The OS events
 260  * are specified (implicitly) from the fd_info struct.
 261  */
 262 static int
 263 reassociate(struct evport_data *epdp, struct fd_info *fdip, int fd)
 264 {
 265         int sysevents = FDI_TO_SYSEVENTS(fdip);
 266
 267         if (sysevents != 0) {
 268                 if (port_associate(epdp->ed_port, PORT_SOURCE_FD,
 269                                    fd, sysevents, NULL) == -1) {
 270                         event_warn("port_associate");
 271                         return (-1);
 272                 }
 273         }
 274
 275         check_evportop(epdp);
 276
 277         return (0);
 278 }
 279
 280 /*
 281  * Main event loop - polls port_getn for some number of events, and processes
 282  * them.
 283  */
 284
 285 static int
 286 evport_dispatch(struct event_base *base, void *arg, struct timeval *tv)
 287 {
 288         int i, res;
 289         struct evport_data *epdp = arg;
 290         port_event_t pevtlist[EVENTS_PER_GETN];
 291
 292         /*
 293          * port_getn will block until it has at least nevents events. It will
 294          * also return how many it's given us (which may be more than we asked
 295          * for, as long as it's less than our maximum (EVENTS_PER_GETN)) in
 296          * nevents.
 297          */
 298         int nevents = 1;
 299
 300         /*
 301          * We have to convert a struct timeval to a struct timespec
 302          * (only difference is nanoseconds vs. microseconds). If no time-based
 303          * events are active, we should wait for I/O (and tv == NULL).
 304          */
 305         struct timespec ts;
 306         struct timespec *ts_p = NULL;
 307         if (tv != NULL) {
 308                 ts.tv_sec = tv->tv_sec;
 309                 ts.tv_nsec = tv->tv_usec * 1000;
 310                 ts_p = &ts;
 311         }
 312
 313         /*
 314          * Before doing anything else, we need to reassociate the events we hit
 315          * last time which need reassociation. See comment at the end of the
 316          * loop below.
 317          */
 318         for (i = 0; i < EVENTS_PER_GETN; ++i) {
 319                 struct fd_info *fdi = NULL;
 320                 if (epdp->ed_pending[i] != -1) {
 321                         fdi = &(epdp->ed_fds[epdp->ed_pending[i]]);
 322                 }
 323
 324                 if (fdi != NULL && FDI_HAS_EVENTS(fdi)) {
 325                         int fd = FDI_HAS_READ(fdi) ? fdi->fdi_revt->ev_fd :
 326                             fdi->fdi_wevt->ev_fd;
 327                         reassociate(epdp, fdi, fd);
 328                         epdp->ed_pending[i] = -1;
 329                 }
 330         }
 331
 332         if ((res = port_getn(epdp->ed_port, pevtlist, EVENTS_PER_GETN,
 333                     (unsigned int *) &nevents, ts_p)) == -1) {
 334                 if (errno == EINTR || errno == EAGAIN) {
 335                         evsignal_process(base);
 336                         return (0);
 337                 } else if (errno == ETIME) {
 338                         if (nevents == 0)
 339                                 return (0);
 340                 } else {
 341                         event_warn("port_getn");
 342                         return (-1);
 343                 }
 344         } else if (base->sig.evsignal_caught) {
 345                 evsignal_process(base);
 346         }
 347
 348         event_debug(("%s: port_getn reports %d events", __func__, nevents));
 349
 350         for (i = 0; i < nevents; ++i) {
 351                 struct event *ev;
 352                 struct fd_info *fdi;
 353                 port_event_t *pevt = &pevtlist[i];
 354                 int fd = (int) pevt->portev_object;
 355
 356                 check_evportop(epdp);
 357                 check_event(pevt);
 358                 epdp->ed_pending[i] = fd;
 359
 360                 /*
 361                  * Figure out what kind of event it was
 362                  * (because we have to pass this to the callback)
 363                  */
 364                 res = 0;
 365                 if (pevt->portev_events & POLLIN)
 366                         res |= EV_READ;
 367                 if (pevt->portev_events & POLLOUT)
 368                         res |= EV_WRITE;
 369
 370                 assert(epdp->ed_nevents > fd);
 371                 fdi = &(epdp->ed_fds[fd]);
 372
 373                 /*
 374                  * We now check for each of the possible events (READ
 375                  * or WRITE).  Then, we activate the event (which will
 376                  * cause its callback to be executed).
 377                  */
 378
 379                 if ((res & EV_READ) && ((ev = fdi->fdi_revt) != NULL)) {
 380                         event_active(ev, res, 1);
 381                 }
 382
 383                 if ((res & EV_WRITE) && ((ev = fdi->fdi_wevt) != NULL)) {
 384                         event_active(ev, res, 1);
 385                 }
 386         } /* end of all events gotten */
 387
 388         check_evportop(epdp);
 389
 390         return (0);
 391 }
 392
 393
 394 /*
 395  * Adds the given event (so that you will be notified when it happens via
 396  * the callback function).
 397  */
 398
 399 static int
 400 evport_add(void *arg, struct event *ev)
 401 {
 402         struct evport_data *evpd = arg;
 403         struct fd_info *fdi;
 404         int factor;
 405
 406         check_evportop(evpd);
 407
 408         /*
 409          * Delegate, if it's not ours to handle.
 410          */
 411         if (ev->ev_events & EV_SIGNAL)
 412                 return (evsignal_add(ev));
 413
 414         /*
 415          * If necessary, grow the file descriptor info table
 416          */
 417
 418         factor = 1;
 419         while (ev->ev_fd >= factor * evpd->ed_nevents)
 420                 factor *= 2;
 421
 422         if (factor > 1) {
 423                 if (-1 == grow(evpd, factor)) {
 424                         return (-1);
 425                 }
 426         }
 427
 428         fdi = &evpd->ed_fds[ev->ev_fd];
 429         if (ev->ev_events & EV_READ)
 430                 fdi->fdi_revt = ev;
 431         if (ev->ev_events & EV_WRITE)
 432                 fdi->fdi_wevt = ev;
 433
 434         return reassociate(evpd, fdi, ev->ev_fd);
 435 }
 436
 437 /*
 438  * Removes the given event from the list of events to wait for.
 439  */
 440
 441 static int
 442 evport_del(void *arg, struct event *ev)
 443 {
 444         struct evport_data *evpd = arg;
 445         struct fd_info *fdi;
 446         int i;
 447         int associated = 1;
 448
 449         check_evportop(evpd);
 450
 451         /*
 452          * Delegate, if it's not ours to handle
 453          */
 454         if (ev->ev_events & EV_SIGNAL) {
 455                 return (evsignal_del(ev));
 456         }
 457
 458         if (evpd->ed_nevents < ev->ev_fd) {
 459                 return (-1);
 460         }
 461
 462         for (i = 0; i < EVENTS_PER_GETN; ++i) {
 463                 if (evpd->ed_pending[i] == ev->ev_fd) {
 464                         associated = 0;
 465                         break;
 466                 }
 467         }
 468
 469         fdi = &evpd->ed_fds[ev->ev_fd];
 470         if (ev->ev_events & EV_READ)
 471                 fdi->fdi_revt = NULL;
 472         if (ev->ev_events & EV_WRITE)
 473                 fdi->fdi_wevt = NULL;
 474
 475         if (associated) {
 476                 if (!FDI_HAS_EVENTS(fdi) &&
 477                     port_dissociate(evpd->ed_port, PORT_SOURCE_FD,
 478                     ev->ev_fd) == -1) {
 479                         /*
 480                          * Ignre EBADFD error the fd could have been closed
 481                          * before event_del() was called.
 482                          */
 483                         if (errno != EBADFD) {
 484                                 event_warn("port_dissociate");
 485                                 return (-1);
 486                         }
 487                 } else {
 488                         if (FDI_HAS_EVENTS(fdi)) {
 489                                 return (reassociate(evpd, fdi, ev->ev_fd));
 490                         }
 491                 }
 492         } else {
 493                 if (fdi->fdi_revt == NULL && fdi->fdi_wevt == NULL) {
 494                         evpd->ed_pending[i] = -1;
 495                 }
 496         }
 497         return 0;
 498 }
 499
 500
 501 static void
 502 evport_dealloc(struct event_base *base, void *arg)
 503 {
 504         struct evport_data *evpd = arg;
 505
 506         evsignal_dealloc(base);
 507
 508         close(evpd->ed_port);
 509
 510         if (evpd->ed_fds)
 511                 free(evpd->ed_fds);
 512         free(evpd);
 513 }