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