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