3 * $Id: sel.c,v 1.6 1999/09/26 14:28:11 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 1.6 1999/09/26 14:28:11 mdw
34 * (sel_select): Almost pointless efficiency tweak.
36 * Revision 1.5 1999/08/31 17:42:22 mdw
37 * New function `sel_force' to force a descriptor to be `selected'.
39 * Revision 1.4 1999/08/19 18:30:26 mdw
40 * Implement hooks for foreign select-using systems (currently not well
43 * Revision 1.3 1999/05/21 22:13:59 mdw
44 * Use new `tv' macros. Fix ordering bug for timeout selectors.
46 * Revision 1.2 1999/05/15 10:33:32 mdw
47 * Fix copyright notices.
49 * Revision 1.1 1999/05/14 21:01:14 mdw
50 * Integrated `select' handling bits from the background resolver project.
54 /*----- Header files ------------------------------------------------------*/
60 #include <sys/types.h>
67 /*----- Main code ---------------------------------------------------------*/
69 /* --- @sel_init@ --- *
71 * Arguments: @sel_state *s@ = pointer to a state block to initialize
75 * Use: Initializes a select state block.
78 void sel_init(sel_state *s)
82 for (i = 0; i < SEL_MODES; i++) {
91 /* --- @sel_initfile@ --- *
93 * Arguments: @sel_state *s@ = select state to attach to
94 * @sel_file *f@ = pointer to a file block to initialize
95 * @int fd@ = the file descriptor to listen to
96 * @unsigned mode@ = what to listen for
97 * @void (*func)(int fd, unsigned mode, void *p)@ = handler
98 * @void *p@ = argument to pass to handler
102 * Use: Initializes a file block ready for use. The file block
103 * isn't added to the list of things to do until a call to
107 void sel_initfile(sel_state *s, sel_file *f,
108 int fd, unsigned mode,
109 void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/),
119 /* --- @sel_addfile@ --- *
121 * Arguments: @sel_file *f@ = pointer to a file block
125 * Use: Adds a file block into the list of things to listen to.
128 void sel_addfile(sel_file *f)
130 sel_file **ff = &f->s->files[f->mode];
132 /* --- This little dance looks like line-noise, but it does the job --- */
134 while (*ff && (*ff)->fd > f->fd)
137 f->prev = (sel_file *)ff;
141 FD_SET(f->fd, f->s->fd + f->mode);
144 /* --- @sel_force@ --- *
146 * Arguments: @sel_file *f@ = pointer to file selector
150 * Use: Forces a file selector to be considered ready. This is only
151 * useful during a call to @sel_select@. Of particular use is
152 * forcing a write selector when there's something interesting
156 void sel_force(sel_file *f)
159 FD_SET(f->fd, &f->s->args->fd[f->mode]);
162 /* --- @sel_rmfile@ --- *
164 * Arguments: @sel_file *f@ = pointer to a file block
168 * Use: Removes a file block from the list of things to listen to.
171 void sel_rmfile(sel_file *f)
173 f->prev->next = f->next;
175 f->next->prev = f->prev;
176 FD_CLR(f->fd, f->s->fd + f->mode);
179 /* --- @sel_addtimer@ --- *
181 * Arguments: @sel_state *s@ = pointer to a state block
182 * @sel_timer *t@ = pointer to a timer block
183 * @struct timeval *tv@ = pointer to time to activate
184 * @void (*func)(struct timeval *tv, void *p)@ = handler
185 * @void *p@ = argument for handler function
189 * Use: Registers and sets up a timer.
192 void sel_addtimer(sel_state *s, sel_timer *t,
194 void (*func)(struct timeval */*tv*/, void */*p*/),
197 sel_timer **tt = &s->timers;
199 /* --- Set up the timer block --- */
205 /* --- More line noise --- */
207 while (*tt && TV_CMP(&(*tt)->tv, <, tv))
210 t->prev = (sel_timer *)tt;
216 /* --- @sel_rmtimer@ --- *
218 * Arguments: @sel_timer *t@ = pointer to timer block
222 * Use: Removes a timer from the list of timers.
225 void sel_rmtimer(sel_timer *t)
227 t->prev->next = t->next;
229 t->next->prev = t->prev;
232 /* --- @sel_addhook@ --- *
234 * Arguments: @sel_state *s@ = pointer to state block
235 * @sel_hook *h@ = pointer to hook block
236 * @sel_hookfn before, after@ = hook functions
237 * @void *p@ = pointer argument to pass to hook functions
241 * Use: Registers hook functions to be called on each select call.
244 void sel_addhook(sel_state *s, sel_hook *h,
245 sel_hookfn before, sel_hookfn after,
252 h->prev = (sel_hook *)&s->hooks;
258 /* --- @sel_rmhook@ --- *
260 * Arguments: @sel_hook *h@ = pointer to hook block
264 * Use: Removes hook functions.
267 void sel_rmhook(sel_hook *h)
270 h->next->prev = h->prev;
271 h->prev->next = h->next;
274 /* --- @sel_fdmerge@ --- *
276 * Arguments: @fd_set *dest@ = destination FD set
277 * @fd_set *fd@ = pointer to set to merge
278 * @int maxfd@ = highest numbered descriptor in @fd@ + 1
280 * Returns: Actual highest numbered descriptor.
282 * Use: Merges file descriptor sets, and returns an accurate @maxfd@
286 int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd)
290 for (i = 0; i < maxfd; i++) {
291 if (FD_ISSET(i, fd)) {
300 /* --- @sel_select@ --- *
302 * Arguments: @sel_state *s@ = pointer to state block
304 * Returns: Zero if all OK, -1 on error.
306 * Use: Does a @select@ call (or equivalent @poll@).
309 int sel_select(sel_state *s)
314 /* --- Initialize the argument block --- */
319 for (i = 0; i < SEL_MODES; i++) {
320 if (s->files[i] && s->files[i]->fd >= a.maxfd)
321 a.maxfd = s->files[i]->fd + 1;
325 memcpy(a.fd, s->fd, sizeof(a.fd));
326 if (s->timers || s->hooks)
327 gettimeofday(&a.now, 0);
331 TV_SUB(&a.tv, &s->timers->tv, &a.now);
336 /* --- Grind through the pre hooks --- */
339 sel_hook *h = s->hooks;
344 hh->before(s, &a, hh->p);
348 /* --- Run the @select@ call --- */
350 if ((err = select(a.maxfd,
351 &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC],
358 gettimeofday(&a.now, 0);
360 /* --- Run through the hooks again --- */
363 sel_hook *h = s->hooks;
368 hh->after(s, &a, hh->p);
372 /* --- Run through the timers --- */
376 for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = tt) {
378 t->next = t->prev = t;
379 t->func(&a.now, t->p);
383 t->prev = (sel_timer *)&s->timers;
386 /* --- And finally run through the files --- *
388 * Do reads first. It's quite possible that a read might prompt a write,
389 * but the other way around is less likely. Fortunately, the modes are
390 * in the right order for this.
396 for (i = 0; i < SEL_MODES; i++) {
398 for (f = s->files[i]; f; f = ff) {
400 if (FD_ISSET(f->fd, a.fd + i))
401 f->func(f->fd, i, f->p);
410 /*----- That's all, folks -------------------------------------------------*/