src/ae.c

   1 /* A simple event-driven programming library. Originally I wrote this code
   2  * for the Jim's event-loop (Jim is a Tcl interpreter) but later translated
   3  * it in form of a library for easy reuse.
   4  *
   5  * Copyright (c) 2006-2010, Salvatore Sanfilippo <antirez at gmail dot com>
   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 are met:
  10  *
  11  *   * Redistributions of source code must retain the above copyright notice,
  12  *     this list of conditions and the following disclaimer.
  13  *   * 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  *   * Neither the name of Redis nor the names of its contributors may be used
  17  *     to endorse or promote products derived from this software without
  18  *     specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  21  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  24  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  30  * POSSIBILITY OF SUCH DAMAGE.
  31  */
  32
  33 #include <stdio.h>
  34 #include <sys/time.h>
  35 #include <sys/types.h>
  36 #include <unistd.h>
  37 #include <stdlib.h>
  38 #include <poll.h>
  39 #include <string.h>
  40
  41 #include "ae.h"
  42 #include "zmalloc.h"
  43 #include "config.h"
  44
  45 /* Include the best multiplexing layer supported by this system.
  46  * The following should be ordered by performances, descending. */
  47 #ifdef HAVE_EVPORT
  48 #include "ae_evport.c"
  49 #else
  50     #ifdef HAVE_EPOLL
  51     #include "ae_epoll.c"
  52     #else
  53         #ifdef HAVE_KQUEUE
  54         #include "ae_kqueue.c"
  55         #else
  56         #include "ae_select.c"
  57         #endif
  58     #endif
  59 #endif
  60
  61 aeEventLoop *aeCreateEventLoop(int setsize) {
  62     aeEventLoop *eventLoop;
  63     int i;
  64
  65     if ((eventLoop = zmalloc(sizeof(*eventLoop))) == NULL) goto err;
  66     eventLoop->events = zmalloc(sizeof(aeFileEvent)*setsize);
  67     eventLoop->fired = zmalloc(sizeof(aeFiredEvent)*setsize);
  68     if (eventLoop->events == NULL || eventLoop->fired == NULL) goto err;
  69     eventLoop->setsize = setsize;
  70     eventLoop->timeEventHead = NULL;
  71     eventLoop->timeEventNextId = 0;
  72     eventLoop->stop = 0;
  73     eventLoop->maxfd = -1;
  74     eventLoop->beforesleep = NULL;
  75     if (aeApiCreate(eventLoop) == -1) goto err;
  76     /* Events with mask == AE_NONE are not set. So let's initialize the
  77      * vector with it. */
  78     for (i = 0; i < setsize; i++)
  79         eventLoop->events[i].mask = AE_NONE;
  80     return eventLoop;
  81
  82 err:
  83     if (eventLoop) {
  84         zfree(eventLoop->events);
  85         zfree(eventLoop->fired);
  86         zfree(eventLoop);
  87     }
  88     return NULL;
  89 }
  90
  91 void aeDeleteEventLoop(aeEventLoop *eventLoop) {
  92     aeApiFree(eventLoop);
  93     zfree(eventLoop->events);
  94     zfree(eventLoop->fired);
  95     zfree(eventLoop);
  96 }
  97
  98 void aeStop(aeEventLoop *eventLoop) {
  99     eventLoop->stop = 1;
 100 }
 101
 102 int aeCreateFileEvent(aeEventLoop *eventLoop, int fd, int mask,
 103         aeFileProc *proc, void *clientData)
 104 {
 105     if (fd >= eventLoop->setsize) return AE_ERR;
 106     aeFileEvent *fe = &eventLoop->events[fd];
 107
 108     if (aeApiAddEvent(eventLoop, fd, mask) == -1)
 109         return AE_ERR;
 110     fe->mask |= mask;
 111     if (mask & AE_READABLE) fe->rfileProc = proc;
 112     if (mask & AE_WRITABLE) fe->wfileProc = proc;
 113     fe->clientData = clientData;
 114     if (fd > eventLoop->maxfd)
 115         eventLoop->maxfd = fd;
 116     return AE_OK;
 117 }
 118
 119 void aeDeleteFileEvent(aeEventLoop *eventLoop, int fd, int mask)
 120 {
 121     if (fd >= eventLoop->setsize) return;
 122     aeFileEvent *fe = &eventLoop->events[fd];
 123
 124     if (fe->mask == AE_NONE) return;
 125     fe->mask = fe->mask & (~mask);
 126     if (fd == eventLoop->maxfd && fe->mask == AE_NONE) {
 127         /* Update the max fd */
 128         int j;
 129
 130         for (j = eventLoop->maxfd-1; j >= 0; j--)
 131             if (eventLoop->events[j].mask != AE_NONE) break;
 132         eventLoop->maxfd = j;
 133     }
 134     aeApiDelEvent(eventLoop, fd, mask);
 135 }
 136
 137 int aeGetFileEvents(aeEventLoop *eventLoop, int fd) {
 138     if (fd >= eventLoop->setsize) return 0;
 139     aeFileEvent *fe = &eventLoop->events[fd];
 140
 141     return fe->mask;
 142 }
 143
 144 static void aeGetTime(long *seconds, long *milliseconds)
 145 {
 146     struct timeval tv;
 147
 148     gettimeofday(&tv, NULL);
 149     *seconds = tv.tv_sec;
 150     *milliseconds = tv.tv_usec/1000;
 151 }
 152
 153 static void aeAddMillisecondsToNow(long long milliseconds, long *sec, long *ms) {
 154     long cur_sec, cur_ms, when_sec, when_ms;
 155
 156     aeGetTime(&cur_sec, &cur_ms);
 157     when_sec = cur_sec + milliseconds/1000;
 158     when_ms = cur_ms + milliseconds%1000;
 159     if (when_ms >= 1000) {
 160         when_sec ++;
 161         when_ms -= 1000;
 162     }
 163     *sec = when_sec;
 164     *ms = when_ms;
 165 }
 166
 167 long long aeCreateTimeEvent(aeEventLoop *eventLoop, long long milliseconds,
 168         aeTimeProc *proc, void *clientData,
 169         aeEventFinalizerProc *finalizerProc)
 170 {
 171     long long id = eventLoop->timeEventNextId++;
 172     aeTimeEvent *te;
 173
 174     te = zmalloc(sizeof(*te));
 175     if (te == NULL) return AE_ERR;
 176     te->id = id;
 177     aeAddMillisecondsToNow(milliseconds,&te->when_sec,&te->when_ms);
 178     te->timeProc = proc;
 179     te->finalizerProc = finalizerProc;
 180     te->clientData = clientData;
 181     te->next = eventLoop->timeEventHead;
 182     eventLoop->timeEventHead = te;
 183     return id;
 184 }
 185
 186 int aeDeleteTimeEvent(aeEventLoop *eventLoop, long long id)
 187 {
 188     aeTimeEvent *te, *prev = NULL;
 189
 190     te = eventLoop->timeEventHead;
 191     while(te) {
 192         if (te->id == id) {
 193             if (prev == NULL)
 194                 eventLoop->timeEventHead = te->next;
 195             else
 196                 prev->next = te->next;
 197             if (te->finalizerProc)
 198                 te->finalizerProc(eventLoop, te->clientData);
 199             zfree(te);
 200             return AE_OK;
 201         }
 202         prev = te;
 203         te = te->next;
 204     }
 205     return AE_ERR; /* NO event with the specified ID found */
 206 }
 207
 208 /* Search the first timer to fire.
 209  * This operation is useful to know how many time the select can be
 210  * put in sleep without to delay any event.
 211  * If there are no timers NULL is returned.
 212  *
 213  * Note that's O(N) since time events are unsorted.
 214  * Possible optimizations (not needed by Redis so far, but...):
 215  * 1) Insert the event in order, so that the nearest is just the head.
 216  *    Much better but still insertion or deletion of timers is O(N).
 217  * 2) Use a skiplist to have this operation as O(1) and insertion as O(log(N)).
 218  */
 219 static aeTimeEvent *aeSearchNearestTimer(aeEventLoop *eventLoop)
 220 {
 221     aeTimeEvent *te = eventLoop->timeEventHead;
 222     aeTimeEvent *nearest = NULL;
 223
 224     while(te) {
 225         if (!nearest || te->when_sec < nearest->when_sec ||
 226                 (te->when_sec == nearest->when_sec &&
 227                  te->when_ms < nearest->when_ms))
 228             nearest = te;
 229         te = te->next;
 230     }
 231     return nearest;
 232 }
 233
 234 /* Process time events */
 235 static int processTimeEvents(aeEventLoop *eventLoop) {
 236     int processed = 0;
 237     aeTimeEvent *te;
 238     long long maxId;
 239
 240     te = eventLoop->timeEventHead;
 241     maxId = eventLoop->timeEventNextId-1;
 242     while(te) {
 243         long now_sec, now_ms;
 244         long long id;
 245
 246         if (te->id > maxId) {
 247             te = te->next;
 248             continue;
 249         }
 250         aeGetTime(&now_sec, &now_ms);
 251         if (now_sec > te->when_sec ||
 252             (now_sec == te->when_sec && now_ms >= te->when_ms))
 253         {
 254             int retval;
 255
 256             id = te->id;
 257             retval = te->timeProc(eventLoop, id, te->clientData);
 258             processed++;
 259             /* After an event is processed our time event list may
 260              * no longer be the same, so we restart from head.
 261              * Still we make sure to don't process events registered
 262              * by event handlers itself in order to don't loop forever.
 263              * To do so we saved the max ID we want to handle.
 264              *
 265              * FUTURE OPTIMIZATIONS:
 266              * Note that this is NOT great algorithmically. Redis uses
 267              * a single time event so it's not a problem but the right
 268              * way to do this is to add the new elements on head, and
 269              * to flag deleted elements in a special way for later
 270              * deletion (putting references to the nodes to delete into
 271              * another linked list). */
 272             if (retval != AE_NOMORE) {
 273                 aeAddMillisecondsToNow(retval,&te->when_sec,&te->when_ms);
 274             } else {
 275                 aeDeleteTimeEvent(eventLoop, id);
 276             }
 277             te = eventLoop->timeEventHead;
 278         } else {
 279             te = te->next;
 280         }
 281     }
 282     return processed;
 283 }
 284
 285 /* Process every pending time event, then every pending file event
 286  * (that may be registered by time event callbacks just processed).
 287  * Without special flags the function sleeps until some file event
 288  * fires, or when the next time event occurrs (if any).
 289  *
 290  * If flags is 0, the function does nothing and returns.
 291  * if flags has AE_ALL_EVENTS set, all the kind of events are processed.
 292  * if flags has AE_FILE_EVENTS set, file events are processed.
 293  * if flags has AE_TIME_EVENTS set, time events are processed.
 294  * if flags has AE_DONT_WAIT set the function returns ASAP until all
 295  * the events that's possible to process without to wait are processed.
 296  *
 297  * The function returns the number of events processed. */
 298 int aeProcessEvents(aeEventLoop *eventLoop, int flags)
 299 {
 300     int processed = 0, numevents;
 301
 302     /* Nothing to do? return ASAP */
 303     if (!(flags & AE_TIME_EVENTS) && !(flags & AE_FILE_EVENTS)) return 0;
 304
 305     /* Note that we want call select() even if there are no
 306      * file events to process as long as we want to process time
 307      * events, in order to sleep until the next time event is ready
 308      * to fire. */
 309     if (eventLoop->maxfd != -1 ||
 310         ((flags & AE_TIME_EVENTS) && !(flags & AE_DONT_WAIT))) {
 311         int j;
 312         aeTimeEvent *shortest = NULL;
 313         struct timeval tv, *tvp;
 314
 315         if (flags & AE_TIME_EVENTS && !(flags & AE_DONT_WAIT))
 316             shortest = aeSearchNearestTimer(eventLoop);
 317         if (shortest) {
 318             long now_sec, now_ms;
 319
 320             /* Calculate the time missing for the nearest
 321              * timer to fire. */
 322             aeGetTime(&now_sec, &now_ms);
 323             tvp = &tv;
 324             tvp->tv_sec = shortest->when_sec - now_sec;
 325             if (shortest->when_ms < now_ms) {
 326                 tvp->tv_usec = ((shortest->when_ms+1000) - now_ms)*1000;
 327                 tvp->tv_sec --;
 328             } else {
 329                 tvp->tv_usec = (shortest->when_ms - now_ms)*1000;
 330             }
 331             if (tvp->tv_sec < 0) tvp->tv_sec = 0;
 332             if (tvp->tv_usec < 0) tvp->tv_usec = 0;
 333         } else {
 334             /* If we have to check for events but need to return
 335              * ASAP because of AE_DONT_WAIT we need to se the timeout
 336              * to zero */
 337             if (flags & AE_DONT_WAIT) {
 338                 tv.tv_sec = tv.tv_usec = 0;
 339                 tvp = &tv;
 340             } else {
 341                 /* Otherwise we can block */
 342                 tvp = NULL; /* wait forever */
 343             }
 344         }
 345
 346         numevents = aeApiPoll(eventLoop, tvp);
 347         for (j = 0; j < numevents; j++) {
 348             aeFileEvent *fe = &eventLoop->events[eventLoop->fired[j].fd];
 349             int mask = eventLoop->fired[j].mask;
 350             int fd = eventLoop->fired[j].fd;
 351             int rfired = 0;
 352
 353             /* note the fe->mask & mask & ... code: maybe an already processed
 354              * event removed an element that fired and we still didn't
 355              * processed, so we check if the event is still valid. */
 356             if (fe->mask & mask & AE_READABLE) {
 357                 rfired = 1;
 358                 fe->rfileProc(eventLoop,fd,fe->clientData,mask);
 359             }
 360             if (fe->mask & mask & AE_WRITABLE) {
 361                 if (!rfired || fe->wfileProc != fe->rfileProc)
 362                     fe->wfileProc(eventLoop,fd,fe->clientData,mask);
 363             }
 364             processed++;
 365         }
 366     }
 367     /* Check time events */
 368     if (flags & AE_TIME_EVENTS)
 369         processed += processTimeEvents(eventLoop);
 370
 371     return processed; /* return the number of processed file/time events */
 372 }
 373
 374 /* Wait for millseconds until the given file descriptor becomes
 375  * writable/readable/exception */
 376 int aeWait(int fd, int mask, long long milliseconds) {
 377     struct pollfd pfd;
 378     int retmask = 0, retval;
 379
 380     memset(&pfd, 0, sizeof(pfd));
 381     pfd.fd = fd;
 382     if (mask & AE_READABLE) pfd.events |= POLLIN;
 383     if (mask & AE_WRITABLE) pfd.events |= POLLOUT;
 384
 385     if ((retval = poll(&pfd, 1, milliseconds))== 1) {
 386         if (pfd.revents & POLLIN) retmask |= AE_READABLE;
 387         if (pfd.revents & POLLOUT) retmask |= AE_WRITABLE;
 388         if (pfd.revents & POLLERR) retmask |= AE_WRITABLE;
 389         if (pfd.revents & POLLHUP) retmask |= AE_WRITABLE;
 390         return retmask;
 391     } else {
 392         return retval;
 393     }
 394 }
 395
 396 void aeMain(aeEventLoop *eventLoop) {
 397     eventLoop->stop = 0;
 398     while (!eventLoop->stop) {
 399         if (eventLoop->beforesleep != NULL)
 400             eventLoop->beforesleep(eventLoop);
 401         aeProcessEvents(eventLoop, AE_ALL_EVENTS);
 402     }
 403 }
 404
 405 char *aeGetApiName(void) {
 406     return aeApiName();
 407 }
 408
 409 void aeSetBeforeSleepProc(aeEventLoop *eventLoop, aeBeforeSleepProc *beforesleep) {
 410     eventLoop->beforesleep = beforesleep;
 411 }