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