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) 2006-2009, 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     if (aeApiCreate(eventLoop) == -1) {
  66         zfree(eventLoop);
  67         return NULL;
  68     }
  69     /* Events with mask == AE_NONE are not set. So let's initialize the
  70      * vector with it. */
  71     for (i = 0; i < AE_SETSIZE; i++)
  72         eventLoop->events[i].mask = AE_NONE;
  73     return eventLoop;
  74 }
  75
  76 void aeDeleteEventLoop(aeEventLoop *eventLoop) {
  77     aeApiFree(eventLoop);
  78     zfree(eventLoop);
  79 }
  80
  81 void aeStop(aeEventLoop *eventLoop) {
  82     eventLoop->stop = 1;
  83 }
  84
  85 int aeCreateFileEvent(aeEventLoop *eventLoop, int fd, int mask,
  86         aeFileProc *proc, void *clientData)
  87 {
  88     if (fd >= AE_SETSIZE) return AE_ERR;
  89     aeFileEvent *fe = &eventLoop->events[fd];
  90
  91     if (aeApiAddEvent(eventLoop, fd, mask) == -1)
  92         return AE_ERR;
  93     fe->mask |= mask;
  94     if (mask & AE_READABLE) fe->rfileProc = proc;
  95     if (mask & AE_WRITABLE) fe->wfileProc = proc;
  96     fe->clientData = clientData;
  97     if (fd > eventLoop->maxfd)
  98         eventLoop->maxfd = fd;
  99     return AE_OK;
 100 }
 101
 102 void aeDeleteFileEvent(aeEventLoop *eventLoop, int fd, int mask)
 103 {
 104     if (fd >= AE_SETSIZE) return;
 105     aeFileEvent *fe = &eventLoop->events[fd];
 106
 107     if (fe->mask == AE_NONE) return;
 108     fe->mask = fe->mask & (~mask);
 109     if (fd == eventLoop->maxfd && fe->mask == AE_NONE) {
 110         /* Update the max fd */
 111         int j;
 112
 113         for (j = eventLoop->maxfd-1; j >= 0; j--)
 114             if (eventLoop->events[j].mask != AE_NONE) break;
 115         eventLoop->maxfd = j;
 116     }
 117     aeApiDelEvent(eventLoop, fd, mask);
 118 }
 119
 120 static void aeGetTime(long *seconds, long *milliseconds)
 121 {
 122     struct timeval tv;
 123
 124     gettimeofday(&tv, NULL);
 125     *seconds = tv.tv_sec;
 126     *milliseconds = tv.tv_usec/1000;
 127 }
 128
 129 static void aeAddMillisecondsToNow(long long milliseconds, long *sec, long *ms) {
 130     long cur_sec, cur_ms, when_sec, when_ms;
 131
 132     aeGetTime(&cur_sec, &cur_ms);
 133     when_sec = cur_sec + milliseconds/1000;
 134     when_ms = cur_ms + milliseconds%1000;
 135     if (when_ms >= 1000) {
 136         when_sec ++;
 137         when_ms -= 1000;
 138     }
 139     *sec = when_sec;
 140     *ms = when_ms;
 141 }
 142
 143 long long aeCreateTimeEvent(aeEventLoop *eventLoop, long long milliseconds,
 144         aeTimeProc *proc, void *clientData,
 145         aeEventFinalizerProc *finalizerProc)
 146 {
 147     long long id = eventLoop->timeEventNextId++;
 148     aeTimeEvent *te;
 149
 150     te = zmalloc(sizeof(*te));
 151     if (te == NULL) return AE_ERR;
 152     te->id = id;
 153     aeAddMillisecondsToNow(milliseconds,&te->when_sec,&te->when_ms);
 154     te->timeProc = proc;
 155     te->finalizerProc = finalizerProc;
 156     te->clientData = clientData;
 157     te->next = eventLoop->timeEventHead;
 158     eventLoop->timeEventHead = te;
 159     return id;
 160 }
 161
 162 int aeDeleteTimeEvent(aeEventLoop *eventLoop, long long id)
 163 {
 164     aeTimeEvent *te, *prev = NULL;
 165
 166     te = eventLoop->timeEventHead;
 167     while(te) {
 168         if (te->id == id) {
 169             if (prev == NULL)
 170                 eventLoop->timeEventHead = te->next;
 171             else
 172                 prev->next = te->next;
 173             if (te->finalizerProc)
 174                 te->finalizerProc(eventLoop, te->clientData);
 175             zfree(te);
 176             return AE_OK;
 177         }
 178         prev = te;
 179         te = te->next;
 180     }
 181     return AE_ERR; /* NO event with the specified ID found */
 182 }
 183
 184 /* Search the first timer to fire.
 185  * This operation is useful to know how many time the select can be
 186  * put in sleep without to delay any event.
 187  * If there are no timers NULL is returned.
 188  *
 189  * Note that's O(N) since time events are unsorted.
 190  * Possible optimizations (not needed by Redis so far, but...):
 191  * 1) Insert the event in order, so that the nearest is just the head.
 192  *    Much better but still insertion or deletion of timers is O(N).
 193  * 2) Use a skiplist to have this operation as O(1) and insertion as O(log(N)).
 194  */
 195 static aeTimeEvent *aeSearchNearestTimer(aeEventLoop *eventLoop)
 196 {
 197     aeTimeEvent *te = eventLoop->timeEventHead;
 198     aeTimeEvent *nearest = NULL;
 199
 200     while(te) {
 201         if (!nearest || te->when_sec < nearest->when_sec ||
 202                 (te->when_sec == nearest->when_sec &&
 203                  te->when_ms < nearest->when_ms))
 204             nearest = te;
 205         te = te->next;
 206     }
 207     return nearest;
 208 }
 209
 210 /* Process time events */
 211 static int processTimeEvents(aeEventLoop *eventLoop) {
 212     int processed = 0;
 213     aeTimeEvent *te;
 214     long long maxId;
 215
 216     te = eventLoop->timeEventHead;
 217     maxId = eventLoop->timeEventNextId-1;
 218     while(te) {
 219         long now_sec, now_ms;
 220         long long id;
 221
 222         if (te->id > maxId) {
 223             te = te->next;
 224             continue;
 225         }
 226         aeGetTime(&now_sec, &now_ms);
 227         if (now_sec > te->when_sec ||
 228             (now_sec == te->when_sec && now_ms >= te->when_ms))
 229         {
 230             int retval;
 231
 232             id = te->id;
 233             retval = te->timeProc(eventLoop, id, te->clientData);
 234             processed++;
 235             /* After an event is processed our time event list may
 236              * no longer be the same, so we restart from head.
 237              * Still we make sure to don't process events registered
 238              * by event handlers itself in order to don't loop forever.
 239              * To do so we saved the max ID we want to handle.
 240              *
 241              * FUTURE OPTIMIZATIONS:
 242              * Note that this is NOT great algorithmically. Redis uses
 243              * a single time event so it's not a problem but the right
 244              * way to do this is to add the new elements on head, and
 245              * to flag deleted elements in a special way for later
 246              * deletion (putting references to the nodes to delete into
 247              * another linked list). */
 248             if (retval != AE_NOMORE) {
 249                 aeAddMillisecondsToNow(retval,&te->when_sec,&te->when_ms);
 250             } else {
 251                 aeDeleteTimeEvent(eventLoop, id);
 252             }
 253             te = eventLoop->timeEventHead;
 254         } else {
 255             te = te->next;
 256         }
 257     }
 258     return processed;
 259 }
 260
 261 /* Process every pending time event, then every pending file event
 262  * (that may be registered by time event callbacks just processed).
 263  * Without special flags the function sleeps until some file event
 264  * fires, or when the next time event occurrs (if any).
 265  *
 266  * If flags is 0, the function does nothing and returns.
 267  * if flags has AE_ALL_EVENTS set, all the kind of events are processed.
 268  * if flags has AE_FILE_EVENTS set, file events are processed.
 269  * if flags has AE_TIME_EVENTS set, time events are processed.
 270  * if flags has AE_DONT_WAIT set the function returns ASAP until all
 271  * the events that's possible to process without to wait are processed.
 272  *
 273  * The function returns the number of events processed. */
 274 int aeProcessEvents(aeEventLoop *eventLoop, int flags)
 275 {
 276     int processed = 0, numevents;
 277
 278     /* Nothing to do? return ASAP */
 279     if (!(flags & AE_TIME_EVENTS) && !(flags & AE_FILE_EVENTS)) return 0;
 280
 281     /* Note that we want call select() even if there are no
 282      * file events to process as long as we want to process time
 283      * events, in order to sleep until the next time event is ready
 284      * to fire. */
 285     if (eventLoop->maxfd != -1 ||
 286         ((flags & AE_TIME_EVENTS) && !(flags & AE_DONT_WAIT))) {
 287         int j;
 288         aeTimeEvent *shortest = NULL;
 289         struct timeval tv, *tvp;
 290
 291         if (flags & AE_TIME_EVENTS && !(flags & AE_DONT_WAIT))
 292             shortest = aeSearchNearestTimer(eventLoop);
 293         if (shortest) {
 294             long now_sec, now_ms;
 295
 296             /* Calculate the time missing for the nearest
 297              * timer to fire. */
 298             aeGetTime(&now_sec, &now_ms);
 299             tvp = &tv;
 300             tvp->tv_sec = shortest->when_sec - now_sec;
 301             if (shortest->when_ms < now_ms) {
 302                 tvp->tv_usec = ((shortest->when_ms+1000) - now_ms)*1000;
 303                 tvp->tv_sec --;
 304             } else {
 305                 tvp->tv_usec = (shortest->when_ms - now_ms)*1000;
 306             }
 307             if (tvp->tv_sec < 0) tvp->tv_sec = 0;
 308             if (tvp->tv_usec < 0) tvp->tv_usec = 0;
 309         } else {
 310             /* If we have to check for events but need to return
 311              * ASAP because of AE_DONT_WAIT we need to se the timeout
 312              * to zero */
 313             if (flags & AE_DONT_WAIT) {
 314                 tv.tv_sec = tv.tv_usec = 0;
 315                 tvp = &tv;
 316             } else {
 317                 /* Otherwise we can block */
 318                 tvp = NULL; /* wait forever */
 319             }
 320         }
 321
 322         numevents = aeApiPoll(eventLoop, tvp);
 323         for (j = 0; j < numevents; j++) {
 324             aeFileEvent *fe = &eventLoop->events[eventLoop->fired[j].fd];
 325             int mask = eventLoop->fired[j].mask;
 326             int fd = eventLoop->fired[j].fd;
 327             int rfired = 0;
 328
 329             /* note the fe->mask & mask & ... code: maybe an already processed
 330              * event removed an element that fired and we still didn't
 331              * processed, so we check if the event is still valid. */
 332             if (fe->mask & mask & AE_READABLE) {
 333                 rfired = 1;
 334                 fe->rfileProc(eventLoop,fd,fe->clientData,mask);
 335             }
 336             if (fe->mask & mask & AE_WRITABLE) {
 337                 if (!rfired || fe->wfileProc != fe->rfileProc)
 338                     fe->wfileProc(eventLoop,fd,fe->clientData,mask);
 339             }
 340             processed++;
 341         }
 342     }
 343     /* Check time events */
 344     if (flags & AE_TIME_EVENTS)
 345         processed += processTimeEvents(eventLoop);
 346
 347     return processed; /* return the number of processed file/time events */
 348 }
 349
 350 /* Wait for millseconds until the given file descriptor becomes
 351  * writable/readable/exception */
 352 int aeWait(int fd, int mask, long long milliseconds) {
 353     struct timeval tv;
 354     fd_set rfds, wfds, efds;
 355     int retmask = 0, retval;
 356
 357     tv.tv_sec = milliseconds/1000;
 358     tv.tv_usec = (milliseconds%1000)*1000;
 359     FD_ZERO(&rfds);
 360     FD_ZERO(&wfds);
 361     FD_ZERO(&efds);
 362
 363     if (mask & AE_READABLE) FD_SET(fd,&rfds);
 364     if (mask & AE_WRITABLE) FD_SET(fd,&wfds);
 365     if ((retval = select(fd+1, &rfds, &wfds, &efds, &tv)) > 0) {
 366         if (FD_ISSET(fd,&rfds)) retmask |= AE_READABLE;
 367         if (FD_ISSET(fd,&wfds)) retmask |= AE_WRITABLE;
 368         return retmask;
 369     } else {
 370         return retval;
 371     }
 372 }
 373
 374 void aeMain(aeEventLoop *eventLoop) {
 375     eventLoop->stop = 0;
 376     while (!eventLoop->stop)
 377         aeProcessEvents(eventLoop, AE_ALL_EVENTS);
 378 }
 379
 380 char *aeGetApiName(void) {
 381     return aeApiName();
 382 }