1 /*
2 * Copyright (c)1996-2002 by Hartmut Brandt
3 * All rights reserved.
4 *
5 * Author: Hartmut Brandt
6 *
7 * Redistribution of this software and documentation and use in source and
8 * binary forms, with or without modification, are permitted provided that
9 * the following conditions are met:
10 *
11 * 1. Redistributions of source code or documentation must retain the above
12 * copyright notice, this list of conditions and the following disclaimer.
13 * 2. 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 *
17 * THIS SOFTWARE AND DOCUMENTATION IS PROVIDED BY THE AUTHOR
18 * AND ITS CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
19 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
21 * THE AUTHOR OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
24 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
26 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29 /*
30 * These functions try to hide the poll/select/setitimer interface from the
31 * user. You associate callback functions with file descriptors and timers.
32 *
33 * $Begemot: libbegemot/rpoll.c,v 1.14 2004/09/21 15:59:00 brandt Exp $
34 */
35 # include <stdio.h>
36 # include <stdlib.h>
37 # include <stddef.h>
38 # include <stdarg.h>
39 # include <signal.h>
40 # include <string.h>
41 # include <errno.h>
42 # include <time.h>
43 # include <assert.h>
44 # include <unistd.h>
45 # include <sys/time.h>
46
47 /*
48 * There happens to be linuxes which read siginfo.h when including
49 * signal.h, which, for no appearent reason, defines these symbols.
50 */
51 # ifdef POLL_IN
52 # undef POLL_IN
53 # endif
54 # ifdef POLL_OUT
55 # undef POLL_OUT
56 # endif
57
58 # include "rpoll.h"
59
60 /*
61 # define DEBUG
62 */
63
64 # ifdef USE_POLL
65 # ifdef NEED_POLL_XOPEN_TWIDDLE
66 # define __USE_XOPEN
67 # endif
68 # include <poll.h>
69 # ifdef NEED_POLL_XOPEN_TWIDDLE
70 # undef __USE_XOPEN
71 # endif
72 # include <stropts.h>
73 # endif
74
75 /*
76 * the second define is for Linux, which sometimes fails to
77 * declare INFTIM.
78 */
79 # if defined(USE_SELECT) || !defined(INFTIM)
80 # define INFTIM (-1)
81 # endif
82
83 # if defined(SIGPOLL)
84 # define SIGNAL SIGPOLL
85 # else
86 # if defined(SIGIO)
87 # define SIGNAL SIGIO
88 # endif
89 # endif
90
91 # ifdef USE_POLL
92 # define poll_in (POLLIN | POLLRDNORM | POLLRDBAND | POLLPRI)
93 # define poll_out (POLLOUT | POLLWRNORM | POLLWRBAND)
94 # define poll_except (POLLERR | POLLHUP)
95 # endif
96
97 # ifdef BROKEN_SELECT_PROTO
98 # define SELECT_CAST(P) (int *)P
99 # else
100 # define SELECT_CAST(P) P
101 # endif
102
103
104 typedef int64_t tval_t;
105
106 static inline tval_t GETUSECS(void);
107
108 static inline tval_t
GETUSECS(void)109 GETUSECS(void) {
110 struct timeval tval;
111
112 (void)gettimeofday(&tval, NULL);
113 return (tval_t)tval.tv_sec * 1000000 + tval.tv_usec;
114 }
115
116 /*
117 * Simple fatal exit.
118 */
119 static void
_panic(const char * fmt,...)120 _panic(const char *fmt, ...)
121 {
122 va_list ap;
123
124 va_start(ap, fmt);
125 fprintf(stderr, "panic: ");
126 vfprintf(stderr, fmt, ap);
127 fprintf(stderr, "\n");
128 va_end(ap);
129
130 exit(1);
131 }
132
133 static void *
_xrealloc(void * p,size_t s)134 _xrealloc(void *p, size_t s)
135 {
136 void *ptr;
137
138 if(p == NULL) {
139 if((ptr=malloc(s)) == NULL && (s!=0 || (ptr=malloc(1)) == NULL))
140 _panic("out of memory: xrealloc(%lx, %lu)",
141 (unsigned long)p, (unsigned long)s);
142 } else if(s == 0) {
143 free(p);
144 if((ptr=malloc(s)) == NULL && (ptr=malloc(1)) == NULL)
145 _panic("out of memory: xrealloc(%lx, %lu)",
146 (unsigned long)p, (unsigned long)s);
147 } else {
148 if((ptr = realloc(p, s)) == NULL)
149 _panic("out of memory: xrealloc(%lx, %lu)",
150 (unsigned long)p, (unsigned long)s);
151 }
152
153 return ptr;
154 }
155
156 /*
157 * This structure holds one registration record for files
158 */
159 typedef struct {
160 int fd; /* file descriptor (-1 if struct unused) */
161 int mask; /* event flags */
162 void * arg; /* client arg */
163 poll_f func; /* handler */
164 # ifdef USE_POLL
165 struct pollfd *pfd; /* pointer to corresponding poll() structure */
166 # endif
167 } PollReg_t;
168
169 /*
170 * Now for timers
171 */
172 typedef struct {
173 uint64_t usecs; /* microsecond value of the timer */
174 int repeat; /* one shot or repeat? */
175 void *arg; /* client arg */
176 timer_f func; /* handler, 0 means disfunct */
177 tval_t when; /* next time to trigger in usecs! */
178 } PollTim_t;
179
180 /* how many records should our table grow at once? */
181 # define POLL_REG_GROW 100
182
183 # ifdef USE_POLL
184 static struct pollfd * pfd; /* fd list for poll() */
185 # endif
186
187 # ifdef USE_SELECT
188 static fd_set rset, wset, xset; /* file descriptor sets for select() */
189 static int maxfd; /* maximum fd number */
190 # endif
191
192 static int in_dispatch;
193
194 static PollReg_t * regs; /* registration records */
195 static u_int regs_alloc; /* how many are allocated */
196 static u_int regs_used; /* upper used limit */
197 static sigset_t bset; /* blocked signals */
198 static int rebuild; /* rebuild table on next dispatch() */
199
200 static int * tfd; /* sorted entries */
201 static u_int tfd_alloc; /* number of entries allocated */
202 static u_int tfd_used; /* number of entries used */
203 static PollTim_t * tims; /* timer registration records */
204 static u_int tims_alloc; /* how many are allocated */
205 static u_int tims_used; /* how many are used */
206 static int resort; /* resort on next dispatch */
207
208 int rpoll_trace;
209 int rpoll_policy; /* if 0 start sched callbacks from 0 else try round robin */
210
211 static void poll_build(void);
212 static void poll_blocksig(void);
213 static void poll_unblocksig(void);
214 static void sort_timers(void);
215
216
217 /*
218 * Private function to block SIGPOLL or SIGIO for a short time.
219 * Don't forget to call poll_unblock before return from the calling function.
220 * Don't change the mask between this calls (your changes will be lost).
221 */
222 static void
poll_blocksig(void)223 poll_blocksig(void)
224 {
225 sigset_t set;
226
227 sigemptyset(&set);
228 sigaddset(&set, SIGNAL);
229
230 if(sigprocmask(SIG_BLOCK, &set, &bset))
231 _panic("sigprocmask(SIG_BLOCK): %s", strerror(errno));
232 }
233
234 /*
235 * unblock the previously blocked signal
236 */
237 static void
poll_unblocksig(void)238 poll_unblocksig(void)
239 {
240 if(sigprocmask(SIG_SETMASK, &bset, NULL))
241 _panic("sigprocmask(SIG_SETMASK): %s", strerror(errno));
242 }
243
244 /*
245 * Register the file descriptor fd. If the event corresponding to
246 * mask arrives func is called with arg.
247 * If fd is already registered with that func and arg, only the mask
248 * is changed.
249 * We block the IO-signal, so the dispatch function can be called from
250 * within the signal handler.
251 */
252 int
poll_register(int fd,poll_f func,void * arg,int mask)253 poll_register(int fd, poll_f func, void *arg, int mask)
254 {
255 PollReg_t * p;
256
257 poll_blocksig();
258
259 /* already registered? */
260 for(p = regs; p < ®s[regs_alloc]; p++)
261 if(p->fd == fd && p->func == func && p->arg == arg) {
262 p->mask = mask;
263 break;
264 }
265
266 if(p == ®s[regs_alloc]) {
267 /* no - register */
268
269 /* find a free slot */
270 for(p = regs; p < ®s[regs_alloc]; p++)
271 if(p->fd == -1)
272 break;
273
274 if(p == ®s[regs_alloc]) {
275 size_t newsize = regs_alloc + POLL_REG_GROW;
276 regs = _xrealloc(regs, sizeof(regs[0]) * newsize);
277 for(p = ®s[regs_alloc]; p < ®s[newsize]; p++) {
278 p->fd = -1;
279 # ifdef USE_POLL
280 p->pfd = NULL;
281 # endif
282 }
283 p = ®s[regs_alloc];
284 regs_alloc = newsize;
285 }
286
287 p->fd = fd;
288 p->arg = arg;
289 p->mask = mask;
290 p->func = func;
291
292 regs_used++;
293 rebuild = 1;
294 }
295
296 poll_unblocksig();
297
298 if(rpoll_trace)
299 fprintf(stderr, "poll_register(%d, %p, %p, %#x)->%tu",
300 fd, (void *)func, (void *)arg, mask, p - regs);
301 return p - regs;
302 }
303
304 /*
305 * remove registration
306 */
307 void
poll_unregister(int handle)308 poll_unregister(int handle)
309 {
310 if(rpoll_trace)
311 fprintf(stderr, "poll_unregister(%d)", handle);
312
313 poll_blocksig();
314
315 regs[handle].fd = -1;
316 # ifdef USE_POLL
317 regs[handle].pfd = NULL;
318 # endif
319 rebuild = 1;
320 regs_used--;
321
322 poll_unblocksig();
323 }
324
325 /*
326 * Build the structures used by poll() or select()
327 */
328 static void
poll_build(void)329 poll_build(void)
330 {
331 PollReg_t * p;
332
333 # ifdef USE_POLL
334 struct pollfd * f;
335
336 f = pfd = _xrealloc(pfd, sizeof(pfd[0]) * regs_used);
337
338 for(p = regs; p < ®s[regs_alloc]; p++)
339 if(p->fd >= 0) {
340 f->fd = p->fd;
341 f->events = 0;
342 if(p->mask & POLL_IN)
343 f->events |= poll_in;
344 if(p->mask & POLL_OUT)
345 f->events |= poll_out;
346 if(p->mask & POLL_EXCEPT)
347 f->events |= poll_except;
348 f->revents = 0;
349 p->pfd = f++;
350 }
351 assert(f == &pfd[regs_used]);
352 # endif
353
354 # ifdef USE_SELECT
355 FD_ZERO(&rset);
356 FD_ZERO(&wset);
357 FD_ZERO(&xset);
358 maxfd = -1;
359 for(p = regs; p < ®s[regs_alloc]; p++)
360 if(p->fd >= 0) {
361 if(p->fd > maxfd)
362 maxfd = p->fd;
363 if(p->mask & POLL_IN)
364 FD_SET(p->fd, &rset);
365 if(p->mask & POLL_OUT)
366 FD_SET(p->fd, &wset);
367 if(p->mask & POLL_EXCEPT)
368 FD_SET(p->fd, &xset);
369 }
370 # endif
371 }
372
373 int
poll_start_timer(u_int msecs,int repeat,timer_f func,void * arg)374 poll_start_timer(u_int msecs, int repeat, timer_f func, void *arg)
375 {
376 return (poll_start_utimer((unsigned long long)msecs * 1000,
377 repeat, func, arg));
378 }
379
380 int
poll_start_utimer(unsigned long long usecs,int repeat,timer_f func,void * arg)381 poll_start_utimer(unsigned long long usecs, int repeat, timer_f func, void *arg)
382 {
383 PollTim_t *p;
384
385 /* find unused entry */
386 for(p = tims; p < &tims[tims_alloc]; p++)
387 if(p->func == NULL)
388 break;
389
390 if(p == &tims[tims_alloc]) {
391 if(tims_alloc == tims_used) {
392 size_t newsize = tims_alloc + POLL_REG_GROW;
393 tims = _xrealloc(tims, sizeof(tims[0]) * newsize);
394 for(p = &tims[tims_alloc]; p < &tims[newsize]; p++)
395 p->func = NULL;
396 p = &tims[tims_alloc];
397 tims_alloc = newsize;
398 }
399 }
400
401 /* create entry */
402 p->usecs = usecs;
403 p->repeat = repeat;
404 p->arg = arg;
405 p->func = func;
406 p->when = GETUSECS() + usecs;
407
408 tims_used++;
409
410 resort = 1;
411
412 if(rpoll_trace)
413 fprintf(stderr, "poll_start_utimer(%llu, %d, %p, %p)->%tu",
414 usecs, repeat, (void *)func, (void *)arg, p - tims);
415
416 return p - tims;
417 }
418
419 /*
420 * Here we have to look into the sorted table, whether any entry there points
421 * into the registration table for the deleted entry. This is needed,
422 * because a unregistration can occure while we are scanning through the
423 * table in dispatch(). Do this only, if we are really there - resorting
424 * will sort out things if we are called from outside the loop.
425 */
426 void
poll_stop_timer(int handle)427 poll_stop_timer(int handle)
428 {
429 u_int i;
430
431 if(rpoll_trace)
432 fprintf(stderr, "poll_stop_timer(%d)", handle);
433
434 tims[handle].func = NULL;
435 tims_used--;
436
437 resort = 1;
438
439 if(!in_dispatch)
440 return;
441
442 for(i = 0; i < tfd_used; i++)
443 if(tfd[i] == handle) {
444 tfd[i] = -1;
445 break;
446 }
447 }
448
449 /*
450 * Squeeze and sort timer table.
451 * Should perhaps use a custom sort.
452 */
453 static int
tim_cmp(const void * p1,const void * p2)454 tim_cmp(const void *p1, const void *p2)
455 {
456 int t1 = *(const int *)p1;
457 int t2 = *(const int *)p2;
458
459 return tims[t1].when < tims[t2].when ? -1
460 : tims[t1].when > tims[t2].when ? +1
461 : 0;
462 }
463
464 /*
465 * Reconstruct the tfd-array. This will be an sorted array of indexes
466 * to the used entries in tims. The next timer to expire will be infront
467 * of the array. tfd_used is the number of used entries. The array is
468 * re-allocated if needed.
469 */
470 static void
sort_timers(void)471 sort_timers(void)
472 {
473 int *pp;
474 u_int i;
475
476 if(tims_used > tfd_alloc) {
477 tfd_alloc = tims_used;
478 tfd = _xrealloc(tfd, sizeof(int *) * tfd_alloc);
479 }
480
481 pp = tfd;
482
483 for(i = 0; i < tims_alloc; i++)
484 if(tims[i].func)
485 *pp++ = i;
486 assert(pp - tfd == (ptrdiff_t)tims_used);
487
488 tfd_used = tims_used;
489 if(tfd_used > 1)
490 qsort(tfd, tfd_used, sizeof(int), tim_cmp);
491 }
492
493 /*
494 * Poll the file descriptors and dispatch to the right function
495 * If wait is true the poll blocks until somewhat happens.
496 * Don't use a pointer here, because the called function may cause
497 * a reallocation! The check for pfd != NULL is required, because
498 * a sequence of unregister/register could make the wrong callback
499 * to be called. So we clear pfd in unregister and check here.
500 */
501 void
poll_dispatch(int wait)502 poll_dispatch(int wait)
503 {
504 u_int i, idx;
505 int ret;
506 tval_t now;
507 tval_t tout;
508 static u_int last_index;
509
510 # ifdef USE_SELECT
511 fd_set nrset, nwset, nxset;
512 struct timeval tv;
513 # endif
514
515 in_dispatch = 1;
516
517 if(rebuild) {
518 rebuild = 0;
519 poll_build();
520 }
521 if(resort) {
522 resort = 0;
523 sort_timers();
524 }
525
526 /* in wait mode - compute the timeout */
527 if(wait) {
528 if(tfd_used) {
529 now = GETUSECS();
530 # ifdef DEBUG
531 {
532 fprintf(stderr, "now=%llu", now);
533 for(i = 0; i < tims_used; i++)
534 fprintf(stderr, "timers[%2d] = %lld",
535 i, tfd[i]->when - now);
536 }
537 # endif
538 if((tout = tims[tfd[0]].when - now) < 0)
539 tout = 0;
540 } else
541 tout = INFTIM;
542 } else
543 tout = 0;
544
545 # ifdef DEBUG
546 fprintf(stderr, "rpoll -- selecting with tout=%u", tout);
547 # endif
548
549 # ifdef USE_POLL
550 ret = poll(pfd, regs_used, tout == INFTIM ? INFTIM : (tout / 1000));
551 # endif
552
553 # ifdef USE_SELECT
554 nrset = rset;
555 nwset = wset;
556 nxset = xset;
557 if(tout != INFTIM) {
558 tv.tv_sec = tout / 1000000;
559 tv.tv_usec = tout % 1000000;
560 }
561 ret = select(maxfd+1,
562 SELECT_CAST(&nrset),
563 SELECT_CAST(&nwset),
564 SELECT_CAST(&nxset), (tout==INFTIM) ? NULL : &tv);
565 # endif
566
567 if(ret == -1) {
568 if(errno == EINTR)
569 return;
570 _panic("poll/select: %s", strerror(errno));
571 }
572
573 /* dispatch files */
574 if(ret > 0) {
575 for(i = 0; i < regs_alloc; i++) {
576 idx = rpoll_policy ? ((last_index+i) % regs_alloc) : i;
577
578 assert(idx < regs_alloc);
579
580 if(regs[idx].fd >= 0) {
581 int mask = 0;
582
583 # ifdef USE_POLL
584 if(regs[idx].pfd) {
585 if ((regs[idx].mask & POLL_IN) &&
586 (regs[idx].pfd->revents & poll_in))
587 mask |= POLL_IN;
588 if ((regs[idx].mask & POLL_OUT) &&
589 (regs[idx].pfd->revents & poll_out))
590 mask |= POLL_OUT;
591 if((regs[idx].mask & POLL_EXCEPT) &&
592 (regs[idx].pfd->revents & poll_except))
593 mask |= POLL_EXCEPT;
594 }
595 # endif
596 # ifdef USE_SELECT
597 if ((regs[idx].mask & POLL_IN) &&
598 FD_ISSET(regs[idx].fd, &nrset))
599 mask |= POLL_IN;
600 if ((regs[idx].mask & POLL_OUT) &&
601 FD_ISSET(regs[idx].fd, &nwset))
602 mask |= POLL_OUT;
603 if ((regs[idx].mask & POLL_EXCEPT) &&
604 FD_ISSET(regs[idx].fd, &nxset))
605 mask |= POLL_EXCEPT;
606 # endif
607 assert(idx < regs_alloc);
608
609 if(mask) {
610 if(rpoll_trace)
611 fprintf(stderr, "poll_dispatch() -- "
612 "file %d/%d %x",
613 regs[idx].fd, idx, mask);
614 (*regs[idx].func)(regs[idx].fd, mask, regs[idx].arg);
615 }
616 }
617
618 }
619 last_index++;
620 }
621
622 /* dispatch timeouts */
623 if(tfd_used) {
624 now = GETUSECS();
625 for(i = 0; i < tfd_used; i++) {
626 if(tfd[i] < 0)
627 continue;
628 if(tims[tfd[i]].when > now)
629 break;
630 if(rpoll_trace)
631 fprintf(stderr, "rpoll_dispatch() -- timeout %d",tfd[i]);
632 (*tims[tfd[i]].func)(tfd[i], tims[tfd[i]].arg);
633 if(tfd[i] < 0)
634 continue;
635 if(tims[tfd[i]].repeat)
636 tims[tfd[i]].when = now + tims[tfd[i]].usecs;
637 else {
638 tims[tfd[i]].func = NULL;
639 tims_used--;
640 tfd[i] = -1;
641 }
642 resort = 1;
643 }
644 }
645 in_dispatch = 0;
646 }
647
648
649 # ifdef TESTME
650 struct timeval start, now;
651 int t0, t1;
652
653 double elaps(void);
654 void infunc(int fd, int mask, void *arg);
655
656 double
elaps(void)657 elaps(void)
658 {
659 gettimeofday(&now, NULL);
660
661 return (double)(10 * now.tv_sec + now.tv_usec / 100000 -
662 10 * start.tv_sec - start.tv_usec / 100000) / 10;
663 }
664
665 void
infunc(int fd,int mask,void * arg)666 infunc(int fd, int mask, void *arg)
667 {
668 char buf[1024];
669 int ret;
670
671 mask = mask;
672 arg = arg;
673 if((ret = read(fd, buf, sizeof(buf))) < 0)
674 _panic("read: %s", strerror(errno));
675 write(1, "stdin:", 6);
676 write(1, buf, ret);
677 }
678
679 void tfunc0(int tid, void *arg);
680 void tfunc1(int tid, void *arg);
681
682 void
tfunc0(int tid,void * arg)683 tfunc0(int tid, void *arg)
684 {
685 printf("%4.1f -- %d: %s\n", elaps(), tid, (char *)arg);
686 }
687 void
tfunc1(int tid,void * arg)688 tfunc1(int tid, void *arg)
689 {
690 printf("%4.1f -- %d: %s\n", elaps(), tid, (char *)arg);
691 }
692 void
tfunc2(int tid,void * arg)693 tfunc2(int tid, void *arg)
694 {
695 static u_int count = 0;
696
697 if (++count % 10000 == 0)
698 printf("%4.1f -- %d\n", elaps(), tid);
699 }
700
701 void first(int tid, void *arg);
702 void second(int tid, void *arg);
703
704 void
second(int tid,void * arg)705 second(int tid, void *arg)
706 {
707 printf("%4.1f -- %d: %s\n", elaps(), tid, (char *)arg);
708 poll_start_utimer(5500000, 0, first, "first");
709 poll_stop_timer(t1);
710 t0 = poll_start_timer(1000, 1, tfunc0, "1 second");
711 }
712 void
first(int tid,void * arg)713 first(int tid, void *arg)
714 {
715 printf("%4.1f -- %d: %s\n", elaps(), tid, (char *)arg);
716 poll_start_timer(3700, 0, second, "second");
717 poll_stop_timer(t0);
718 t1 = poll_start_timer(250, 1, tfunc1, "1/4 second");
719 }
720
721 int
main(int argc,char * argv[])722 main(int argc, char *argv[])
723 {
724 argv = argv;
725 gettimeofday(&start, NULL);
726 poll_register(0, infunc, NULL, POLL_IN);
727
728 if (argc < 2) {
729 t0 = poll_start_timer(1000, 1, tfunc0, "1 second");
730 poll_start_timer(2500, 0, first, "first");
731 } else {
732 t0 = poll_start_utimer(300, 1, tfunc2, NULL);
733 }
734
735 while(1)
736 poll_dispatch(1);
737
738 return 0;
739 }
740 # endif
741