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 #include <time.h>
41 #include <errno.h>
42
43 #include "ae.h"
44 #include "zmalloc.h"
45 #include "config.h"
46
47 /* Include the best multiplexing layer supported by this system.
48 * The following should be ordered by performances, descending. */
49 #ifdef HAVE_EVPORT
50 #include "ae_evport.c"
51 #else
52 #ifdef HAVE_EPOLL
53 #include "ae_epoll.c"
54 #else
55 #ifdef HAVE_KQUEUE
56 #include "ae_kqueue.c"
57 #else
58 #include "ae_select.c"
59 #endif
60 #endif
61 #endif
62
aeCreateEventLoop(int setsize)63 aeEventLoop *aeCreateEventLoop(int setsize) {
64 aeEventLoop *eventLoop;
65 int i;
66
67 if ((eventLoop = zmalloc(sizeof(*eventLoop))) == NULL) goto err;
68 eventLoop->events = zmalloc(sizeof(aeFileEvent)*setsize);
69 eventLoop->fired = zmalloc(sizeof(aeFiredEvent)*setsize);
70 if (eventLoop->events == NULL || eventLoop->fired == NULL) goto err;
71 eventLoop->setsize = setsize;
72 eventLoop->lastTime = time(NULL);
73 eventLoop->timeEventHead = NULL;
74 eventLoop->timeEventNextId = 0;
75 eventLoop->stop = 0;
76 eventLoop->maxfd = -1;
77 eventLoop->beforesleep = NULL;
78 if (aeApiCreate(eventLoop) == -1) goto err;
79 /* Events with mask == AE_NONE are not set. So let's initialize the
80 * vector with it. */
81 for (i = 0; i < setsize; i++)
82 eventLoop->events[i].mask = AE_NONE;
83 return eventLoop;
84
85 err:
86 if (eventLoop) {
87 zfree(eventLoop->events);
88 zfree(eventLoop->fired);
89 zfree(eventLoop);
90 }
91 return NULL;
92 }
93
94 /* Return the current set size. */
aeGetSetSize(aeEventLoop * eventLoop)95 int aeGetSetSize(aeEventLoop *eventLoop) {
96 return eventLoop->setsize;
97 }
98
99 /* Resize the maximum set size of the event loop.
100 * If the requested set size is smaller than the current set size, but
101 * there is already a file descriptor in use that is >= the requested
102 * set size minus one, AE_ERR is returned and the operation is not
103 * performed at all.
104 *
105 * Otherwise AE_OK is returned and the operation is successful. */
aeResizeSetSize(aeEventLoop * eventLoop,int setsize)106 int aeResizeSetSize(aeEventLoop *eventLoop, int setsize) {
107 int i;
108
109 if (setsize == eventLoop->setsize) return AE_OK;
110 if (eventLoop->maxfd >= setsize) return AE_ERR;
111 if (aeApiResize(eventLoop,setsize) == -1) return AE_ERR;
112
113 eventLoop->events = zrealloc(eventLoop->events,sizeof(aeFileEvent)*setsize);
114 eventLoop->fired = zrealloc(eventLoop->fired,sizeof(aeFiredEvent)*setsize);
115 eventLoop->setsize = setsize;
116
117 /* Make sure that if we created new slots, they are initialized with
118 * an AE_NONE mask. */
119 for (i = eventLoop->maxfd+1; i < setsize; i++)
120 eventLoop->events[i].mask = AE_NONE;
121 return AE_OK;
122 }
123
aeDeleteEventLoop(aeEventLoop * eventLoop)124 void aeDeleteEventLoop(aeEventLoop *eventLoop) {
125 aeApiFree(eventLoop);
126 zfree(eventLoop->events);
127 zfree(eventLoop->fired);
128 zfree(eventLoop);
129 }
130
aeStop(aeEventLoop * eventLoop)131 void aeStop(aeEventLoop *eventLoop) {
132 eventLoop->stop = 1;
133 }
134
aeCreateFileEvent(aeEventLoop * eventLoop,int fd,int mask,aeFileProc * proc,void * clientData)135 int aeCreateFileEvent(aeEventLoop *eventLoop, int fd, int mask,
136 aeFileProc *proc, void *clientData)
137 {
138 if (fd >= eventLoop->setsize) {
139 errno = ERANGE;
140 return AE_ERR;
141 }
142 aeFileEvent *fe = &eventLoop->events[fd];
143
144 if (aeApiAddEvent(eventLoop, fd, mask) == -1)
145 return AE_ERR;
146 fe->mask |= mask;
147 if (mask & AE_READABLE) fe->rfileProc = proc;
148 if (mask & AE_WRITABLE) fe->wfileProc = proc;
149 fe->clientData = clientData;
150 if (fd > eventLoop->maxfd)
151 eventLoop->maxfd = fd;
152 return AE_OK;
153 }
154
aeDeleteFileEvent(aeEventLoop * eventLoop,int fd,int mask)155 void aeDeleteFileEvent(aeEventLoop *eventLoop, int fd, int mask)
156 {
157 if (fd >= eventLoop->setsize) return;
158 aeFileEvent *fe = &eventLoop->events[fd];
159 if (fe->mask == AE_NONE) return;
160
161 aeApiDelEvent(eventLoop, fd, mask);
162 fe->mask = fe->mask & (~mask);
163 if (fd == eventLoop->maxfd && fe->mask == AE_NONE) {
164 /* Update the max fd */
165 int j;
166
167 for (j = eventLoop->maxfd-1; j >= 0; j--)
168 if (eventLoop->events[j].mask != AE_NONE) break;
169 eventLoop->maxfd = j;
170 }
171 }
172
aeGetFileEvents(aeEventLoop * eventLoop,int fd)173 int aeGetFileEvents(aeEventLoop *eventLoop, int fd) {
174 if (fd >= eventLoop->setsize) return 0;
175 aeFileEvent *fe = &eventLoop->events[fd];
176
177 return fe->mask;
178 }
179
aeGetTime(long * seconds,long * milliseconds)180 static void aeGetTime(long *seconds, long *milliseconds)
181 {
182 struct timeval tv;
183
184 gettimeofday(&tv, NULL);
185 *seconds = tv.tv_sec;
186 *milliseconds = tv.tv_usec/1000;
187 }
188
aeAddMillisecondsToNow(long long milliseconds,long * sec,long * ms)189 static void aeAddMillisecondsToNow(long long milliseconds, long *sec, long *ms) {
190 long cur_sec, cur_ms, when_sec, when_ms;
191
192 aeGetTime(&cur_sec, &cur_ms);
193 when_sec = cur_sec + milliseconds/1000;
194 when_ms = cur_ms + milliseconds%1000;
195 if (when_ms >= 1000) {
196 when_sec ++;
197 when_ms -= 1000;
198 }
199 *sec = when_sec;
200 *ms = when_ms;
201 }
202
aeCreateTimeEvent(aeEventLoop * eventLoop,long long milliseconds,aeTimeProc * proc,void * clientData,aeEventFinalizerProc * finalizerProc)203 long long aeCreateTimeEvent(aeEventLoop *eventLoop, long long milliseconds,
204 aeTimeProc *proc, void *clientData,
205 aeEventFinalizerProc *finalizerProc)
206 {
207 long long id = eventLoop->timeEventNextId++;
208 aeTimeEvent *te;
209
210 te = zmalloc(sizeof(*te));
211 if (te == NULL) return AE_ERR;
212 te->id = id;
213 aeAddMillisecondsToNow(milliseconds,&te->when_sec,&te->when_ms);
214 te->timeProc = proc;
215 te->finalizerProc = finalizerProc;
216 te->clientData = clientData;
217 te->next = eventLoop->timeEventHead;
218 eventLoop->timeEventHead = te;
219 return id;
220 }
221
aeDeleteTimeEvent(aeEventLoop * eventLoop,long long id)222 int aeDeleteTimeEvent(aeEventLoop *eventLoop, long long id)
223 {
224 aeTimeEvent *te, *prev = NULL;
225
226 te = eventLoop->timeEventHead;
227 while(te) {
228 if (te->id == id) {
229 if (prev == NULL)
230 eventLoop->timeEventHead = te->next;
231 else
232 prev->next = te->next;
233 if (te->finalizerProc)
234 te->finalizerProc(eventLoop, te->clientData);
235 zfree(te);
236 return AE_OK;
237 }
238 prev = te;
239 te = te->next;
240 }
241 return AE_ERR; /* NO event with the specified ID found */
242 }
243
244 /* Search the first timer to fire.
245 * This operation is useful to know how many time the select can be
246 * put in sleep without to delay any event.
247 * If there are no timers NULL is returned.
248 *
249 * Note that's O(N) since time events are unsorted.
250 * Possible optimizations (not needed by Redis so far, but...):
251 * 1) Insert the event in order, so that the nearest is just the head.
252 * Much better but still insertion or deletion of timers is O(N).
253 * 2) Use a skiplist to have this operation as O(1) and insertion as O(log(N)).
254 */
aeSearchNearestTimer(aeEventLoop * eventLoop)255 static aeTimeEvent *aeSearchNearestTimer(aeEventLoop *eventLoop)
256 {
257 aeTimeEvent *te = eventLoop->timeEventHead;
258 aeTimeEvent *nearest = NULL;
259
260 while(te) {
261 if (!nearest || te->when_sec < nearest->when_sec ||
262 (te->when_sec == nearest->when_sec &&
263 te->when_ms < nearest->when_ms))
264 nearest = te;
265 te = te->next;
266 }
267 return nearest;
268 }
269
270 /* Process time events */
processTimeEvents(aeEventLoop * eventLoop)271 static int processTimeEvents(aeEventLoop *eventLoop) {
272 int processed = 0;
273 aeTimeEvent *te;
274 long long maxId;
275 time_t now = time(NULL);
276
277 /* If the system clock is moved to the future, and then set back to the
278 * right value, time events may be delayed in a random way. Often this
279 * means that scheduled operations will not be performed soon enough.
280 *
281 * Here we try to detect system clock skews, and force all the time
282 * events to be processed ASAP when this happens: the idea is that
283 * processing events earlier is less dangerous than delaying them
284 * indefinitely, and practice suggests it is. */
285 if (now < eventLoop->lastTime) {
286 te = eventLoop->timeEventHead;
287 while(te) {
288 te->when_sec = 0;
289 te = te->next;
290 }
291 }
292 eventLoop->lastTime = now;
293
294 te = eventLoop->timeEventHead;
295 maxId = eventLoop->timeEventNextId-1;
296 while(te) {
297 long now_sec, now_ms;
298 long long id;
299
300 if (te->id > maxId) {
301 te = te->next;
302 continue;
303 }
304 aeGetTime(&now_sec, &now_ms);
305 if (now_sec > te->when_sec ||
306 (now_sec == te->when_sec && now_ms >= te->when_ms))
307 {
308 int retval;
309
310 id = te->id;
311 retval = te->timeProc(eventLoop, id, te->clientData);
312 processed++;
313 /* After an event is processed our time event list may
314 * no longer be the same, so we restart from head.
315 * Still we make sure to don't process events registered
316 * by event handlers itself in order to don't loop forever.
317 * To do so we saved the max ID we want to handle.
318 *
319 * FUTURE OPTIMIZATIONS:
320 * Note that this is NOT great algorithmically. Redis uses
321 * a single time event so it's not a problem but the right
322 * way to do this is to add the new elements on head, and
323 * to flag deleted elements in a special way for later
324 * deletion (putting references to the nodes to delete into
325 * another linked list). */
326 if (retval != AE_NOMORE) {
327 aeAddMillisecondsToNow(retval,&te->when_sec,&te->when_ms);
328 } else {
329 aeDeleteTimeEvent(eventLoop, id);
330 }
331 te = eventLoop->timeEventHead;
332 } else {
333 te = te->next;
334 }
335 }
336 return processed;
337 }
338
339 /* Process every pending time event, then every pending file event
340 * (that may be registered by time event callbacks just processed).
341 * Without special flags the function sleeps until some file event
342 * fires, or when the next time event occurs (if any).
343 *
344 * If flags is 0, the function does nothing and returns.
345 * if flags has AE_ALL_EVENTS set, all the kind of events are processed.
346 * if flags has AE_FILE_EVENTS set, file events are processed.
347 * if flags has AE_TIME_EVENTS set, time events are processed.
348 * if flags has AE_DONT_WAIT set the function returns ASAP until all
349 * the events that's possible to process without to wait are processed.
350 *
351 * The function returns the number of events processed. */
aeProcessEvents(aeEventLoop * eventLoop,int flags)352 int aeProcessEvents(aeEventLoop *eventLoop, int flags)
353 {
354 int processed = 0, numevents;
355
356 /* Nothing to do? return ASAP */
357 if (!(flags & AE_TIME_EVENTS) && !(flags & AE_FILE_EVENTS)) return 0;
358
359 /* Note that we want call select() even if there are no
360 * file events to process as long as we want to process time
361 * events, in order to sleep until the next time event is ready
362 * to fire. */
363 if (eventLoop->maxfd != -1 ||
364 ((flags & AE_TIME_EVENTS) && !(flags & AE_DONT_WAIT))) {
365 int j;
366 aeTimeEvent *shortest = NULL;
367 struct timeval tv, *tvp;
368
369 if (flags & AE_TIME_EVENTS && !(flags & AE_DONT_WAIT))
370 shortest = aeSearchNearestTimer(eventLoop);
371 if (shortest) {
372 long now_sec, now_ms;
373
374 /* Calculate the time missing for the nearest
375 * timer to fire. */
376 aeGetTime(&now_sec, &now_ms);
377 tvp = &tv;
378 tvp->tv_sec = shortest->when_sec - now_sec;
379 if (shortest->when_ms < now_ms) {
380 tvp->tv_usec = ((shortest->when_ms+1000) - now_ms)*1000;
381 tvp->tv_sec --;
382 } else {
383 tvp->tv_usec = (shortest->when_ms - now_ms)*1000;
384 }
385 if (tvp->tv_sec < 0) tvp->tv_sec = 0;
386 if (tvp->tv_usec < 0) tvp->tv_usec = 0;
387 } else {
388 /* If we have to check for events but need to return
389 * ASAP because of AE_DONT_WAIT we need to set the timeout
390 * to zero */
391 if (flags & AE_DONT_WAIT) {
392 tv.tv_sec = tv.tv_usec = 0;
393 tvp = &tv;
394 } else {
395 /* Otherwise we can block */
396 tvp = NULL; /* wait forever */
397 }
398 }
399
400 numevents = aeApiPoll(eventLoop, tvp);
401 for (j = 0; j < numevents; j++) {
402 aeFileEvent *fe = &eventLoop->events[eventLoop->fired[j].fd];
403 int mask = eventLoop->fired[j].mask;
404 int fd = eventLoop->fired[j].fd;
405 int rfired = 0;
406
407 /* note the fe->mask & mask & ... code: maybe an already processed
408 * event removed an element that fired and we still didn't
409 * processed, so we check if the event is still valid. */
410 if (fe->mask & mask & AE_READABLE) {
411 rfired = 1;
412 fe->rfileProc(eventLoop,fd,fe->clientData,mask);
413 }
414 if (fe->mask & mask & AE_WRITABLE) {
415 if (!rfired || fe->wfileProc != fe->rfileProc)
416 fe->wfileProc(eventLoop,fd,fe->clientData,mask);
417 }
418 processed++;
419 }
420 }
421 /* Check time events */
422 if (flags & AE_TIME_EVENTS)
423 processed += processTimeEvents(eventLoop);
424
425 return processed; /* return the number of processed file/time events */
426 }
427
428 /* Wait for milliseconds until the given file descriptor becomes
429 * writable/readable/exception */
aeWait(int fd,int mask,long long milliseconds)430 int aeWait(int fd, int mask, long long milliseconds) {
431 struct pollfd pfd;
432 int retmask = 0, retval;
433
434 memset(&pfd, 0, sizeof(pfd));
435 pfd.fd = fd;
436 if (mask & AE_READABLE) pfd.events |= POLLIN;
437 if (mask & AE_WRITABLE) pfd.events |= POLLOUT;
438
439 if ((retval = poll(&pfd, 1, milliseconds))== 1) {
440 if (pfd.revents & POLLIN) retmask |= AE_READABLE;
441 if (pfd.revents & POLLOUT) retmask |= AE_WRITABLE;
442 if (pfd.revents & POLLERR) retmask |= AE_WRITABLE;
443 if (pfd.revents & POLLHUP) retmask |= AE_WRITABLE;
444 return retmask;
445 } else {
446 return retval;
447 }
448 }
449
aeMain(aeEventLoop * eventLoop)450 void aeMain(aeEventLoop *eventLoop) {
451 eventLoop->stop = 0;
452 while (!eventLoop->stop) {
453 if (eventLoop->beforesleep != NULL)
454 eventLoop->beforesleep(eventLoop);
455 aeProcessEvents(eventLoop, AE_ALL_EVENTS);
456 }
457 }
458
aeGetApiName(void)459 char *aeGetApiName(void) {
460 return aeApiName();
461 }
462
aeSetBeforeSleepProc(aeEventLoop * eventLoop,aeBeforeSleepProc * beforesleep)463 void aeSetBeforeSleepProc(aeEventLoop *eventLoop, aeBeforeSleepProc *beforesleep) {
464 eventLoop->beforesleep = beforesleep;
465 }
466