3 * $Id: sel.c,v 1.9 2001/02/03 19:07:08 mdw Exp $
5 * I/O multiplexing support
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
14 * mLib is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.9 2001/02/03 19:07:08 mdw
34 * Ensure that timers set to go off in the past don't case a problem.
36 * Revision 1.8 2000/03/23 20:42:08 mdw
37 * Rearrange timeout handling to avoid list corruptions.
39 * Revision 1.7 1999/12/11 11:12:17 mdw
40 * Fix comment formatting error.
42 * Revision 1.6 1999/09/26 14:28:11 mdw
43 * (sel_select): Almost pointless efficiency tweak.
45 * Revision 1.5 1999/08/31 17:42:22 mdw
46 * New function `sel_force' to force a descriptor to be `selected'.
48 * Revision 1.4 1999/08/19 18:30:26 mdw
49 * Implement hooks for foreign select-using systems (currently not well
52 * Revision 1.3 1999/05/21 22:13:59 mdw
53 * Use new `tv' macros. Fix ordering bug for timeout selectors.
55 * Revision 1.2 1999/05/15 10:33:32 mdw
56 * Fix copyright notices.
58 * Revision 1.1 1999/05/14 21:01:14 mdw
59 * Integrated `select' handling bits from the background resolver project.
63 /*----- Header files ------------------------------------------------------*/
69 #include <sys/types.h>
76 /*----- Main code ---------------------------------------------------------*/
78 /* --- @sel_init@ --- *
80 * Arguments: @sel_state *s@ = pointer to a state block to initialize
84 * Use: Initializes a select state block.
87 void sel_init(sel_state *s)
91 for (i = 0; i < SEL_MODES; i++) {
100 /* --- @sel_initfile@ --- *
102 * Arguments: @sel_state *s@ = select state to attach to
103 * @sel_file *f@ = pointer to a file block to initialize
104 * @int fd@ = the file descriptor to listen to
105 * @unsigned mode@ = what to listen for
106 * @void (*func)(int fd, unsigned mode, void *p)@ = handler
107 * @void *p@ = argument to pass to handler
111 * Use: Initializes a file block ready for use. The file block
112 * isn't added to the list of things to do until a call to
116 void sel_initfile(sel_state *s, sel_file *f,
117 int fd, unsigned mode,
118 void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/),
128 /* --- @sel_addfile@ --- *
130 * Arguments: @sel_file *f@ = pointer to a file block
134 * Use: Adds a file block into the list of things to listen to.
137 void sel_addfile(sel_file *f)
139 sel_file **ff = &f->s->files[f->mode];
141 /* --- This little dance looks like line-noise, but it does the job --- */
143 while (*ff && (*ff)->fd > f->fd)
146 f->prev = (sel_file *)ff;
150 FD_SET(f->fd, f->s->fd + f->mode);
153 /* --- @sel_force@ --- *
155 * Arguments: @sel_file *f@ = pointer to file selector
159 * Use: Forces a file selector to be considered ready. This is only
160 * useful during a call to @sel_select@. Of particular use is
161 * forcing a write selector when there's something interesting
165 void sel_force(sel_file *f)
168 FD_SET(f->fd, &f->s->args->fd[f->mode]);
171 /* --- @sel_rmfile@ --- *
173 * Arguments: @sel_file *f@ = pointer to a file block
177 * Use: Removes a file block from the list of things to listen to.
180 void sel_rmfile(sel_file *f)
182 f->prev->next = f->next;
184 f->next->prev = f->prev;
185 FD_CLR(f->fd, f->s->fd + f->mode);
188 /* --- @sel_addtimer@ --- *
190 * Arguments: @sel_state *s@ = pointer to a state block
191 * @sel_timer *t@ = pointer to a timer block
192 * @struct timeval *tv@ = pointer to time to activate
193 * @void (*func)(struct timeval *tv, void *p)@ = handler
194 * @void *p@ = argument for handler function
198 * Use: Registers and sets up a timer.
201 void sel_addtimer(sel_state *s, sel_timer *t,
203 void (*func)(struct timeval */*tv*/, void */*p*/),
206 sel_timer **tt = &s->timers;
208 /* --- Set up the timer block --- */
214 /* --- More line noise --- */
216 while (*tt && TV_CMP(&(*tt)->tv, <, tv))
219 t->prev = (sel_timer *)tt;
225 /* --- @sel_rmtimer@ --- *
227 * Arguments: @sel_timer *t@ = pointer to timer block
231 * Use: Removes a timer from the list of timers.
234 void sel_rmtimer(sel_timer *t)
236 t->prev->next = t->next;
238 t->next->prev = t->prev;
241 /* --- @sel_addhook@ --- *
243 * Arguments: @sel_state *s@ = pointer to state block
244 * @sel_hook *h@ = pointer to hook block
245 * @sel_hookfn before, after@ = hook functions
246 * @void *p@ = pointer argument to pass to hook functions
250 * Use: Registers hook functions to be called on each select call.
253 void sel_addhook(sel_state *s, sel_hook *h,
254 sel_hookfn before, sel_hookfn after,
261 h->prev = (sel_hook *)&s->hooks;
267 /* --- @sel_rmhook@ --- *
269 * Arguments: @sel_hook *h@ = pointer to hook block
273 * Use: Removes hook functions.
276 void sel_rmhook(sel_hook *h)
279 h->next->prev = h->prev;
280 h->prev->next = h->next;
283 /* --- @sel_fdmerge@ --- *
285 * Arguments: @fd_set *dest@ = destination FD set
286 * @fd_set *fd@ = pointer to set to merge
287 * @int maxfd@ = highest numbered descriptor in @fd@ + 1
289 * Returns: Actual highest numbered descriptor.
291 * Use: Merges file descriptor sets, and returns an accurate @maxfd@
295 int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd)
299 for (i = 0; i < maxfd; i++) {
300 if (FD_ISSET(i, fd)) {
309 /* --- @sel_select@ --- *
311 * Arguments: @sel_state *s@ = pointer to state block
313 * Returns: Zero if all OK, -1 on error.
315 * Use: Does a @select@ call (or equivalent @poll@).
318 int sel_select(sel_state *s)
323 /* --- Initialize the argument block --- */
328 for (i = 0; i < SEL_MODES; i++) {
329 if (s->files[i] && s->files[i]->fd >= a.maxfd)
330 a.maxfd = s->files[i]->fd + 1;
334 memcpy(a.fd, s->fd, sizeof(a.fd));
335 if (s->timers || s->hooks)
336 gettimeofday(&a.now, 0);
340 if (TV_CMP(&s->timers->tv, >, &a.now))
341 TV_SUB(&a.tv, &s->timers->tv, &a.now);
350 /* --- Grind through the pre hooks --- */
353 sel_hook *h = s->hooks;
358 hh->before(s, &a, hh->p);
362 /* --- Run the @select@ call --- */
364 if ((err = select(a.maxfd,
365 &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC],
372 gettimeofday(&a.now, 0);
374 /* --- Run through the hooks again --- */
377 sel_hook *h = s->hooks;
382 hh->after(s, &a, hh->p);
386 /* --- Run through the timers --- */
388 if (s->timers && TV_CMP(&s->timers->tv, <=, &a.now)) {
391 for (t = tt; t && TV_CMP(&t->tv, <=, &a.now); t = t->next)
395 t->prev = (sel_timer *)&s->timers;
398 for (t = tt; t; t = tt) {
400 t->func(&a.now, t->p);
404 /* --- And finally run through the files --- *
406 * Do reads first. It's quite possible that a read might prompt a write,
407 * but the other way around is less likely. Fortunately, the modes are
408 * in the right order for this.
414 for (i = 0; i < SEL_MODES; i++) {
416 for (f = s->files[i]; f; f = ff) {
418 if (FD_ISSET(f->fd, a.fd + i))
419 f->func(f->fd, i, f->p);
428 /*----- That's all, folks -------------------------------------------------*/