4 * This module tracks any timers set up by schedule_timer(). It
5 * keeps all the currently active timers in a list; it informs the
6 * front end of when the next timer is due to go off if that
7 * changes; and, very importantly, it tracks the context pointers
8 * passed to schedule_timer(), so that if a context is freed all
9 * the timers associated with it can be immediately annulled.
24 static tree234 *timers = NULL;
25 static tree234 *timer_contexts = NULL;
28 static int compare_timers(void *av, void *bv)
30 struct timer *a = (struct timer *)av;
31 struct timer *b = (struct timer *)bv;
32 long at = a->now - now;
33 long bt = b->now - now;
41 * Failing that, compare on the other two fields, just so that
42 * we don't get unwanted equality.
46 else if (a->fn > b->fn)
51 else if (a->ctx > b->ctx)
55 * Failing _that_, the two entries genuinely are equal, and we
56 * never have a need to store them separately in the tree.
61 static int compare_timer_contexts(void *av, void *bv)
72 static void init_timers(void)
75 timers = newtree234(compare_timers);
76 timer_contexts = newtree234(compare_timer_contexts);
81 long schedule_timer(int ticks, timer_fn_t fn, void *ctx)
84 struct timer *t, *first;
88 when = ticks + GETTICKCOUNT();
89 assert(when - now > 0);
91 t = snew(struct timer);
96 if (t != add234(timers, t)) {
97 sfree(t); /* identical timer already exists */
99 add234(timer_contexts, t->ctx);/* don't care if this fails */
102 first = (struct timer *)index234(timers, 0);
105 * This timer is the very first on the list, so we must
106 * notify the front end.
108 timer_change_notify(first->now);
115 * Call to run any timers whose time has reached the present.
116 * Returns the time (in ticks) expected until the next timer after
119 int run_timers(long anow, long *next)
128 first = (struct timer *)index234(timers, 0);
131 return FALSE; /* no timers remaining */
133 if (find234(timer_contexts, first->ctx, NULL) == NULL) {
135 * This timer belongs to a context that has been
136 * expired. Delete it without running.
138 delpos234(timers, 0);
140 } else if (first->now - now <= 0) {
142 * This timer is active and has reached its running
145 delpos234(timers, 0);
146 first->fn(first->ctx, first->now);
150 * This is the first still-active timer that is in the
151 * future. Return how long it has yet to go.
160 * Call to expire all timers associated with a given context.
162 void expire_timer_context(void *ctx)
167 * We don't bother to check the return value; if the context
168 * already wasn't in the tree (presumably because no timers
169 * ever actually got scheduled for it) then that's fine and we
170 * simply don't need to do anything.
172 del234(timer_contexts, ctx);