Dogcows Code - chaz/openbox/blob - openbox/timer.c

   1 #include "timer.h"
   2
   3 #ifdef    HAVE_SYS_TIME_H
   4 #  include <sys/time.h>
   5 #endif
   6
   7 static GTimeVal now;
   8 static GTimeVal ret_wait;
   9 static GSList *timers; /* nearest timer is at the top */
  10
  11 #define NEAREST_TIMEOUT (((Timer*)timers->data)->timeout)
  12
  13 static long timecompare(GTimeVal *a, GTimeVal *b)
  14 {
  15     long r;
  16
  17     if ((r = b->tv_sec - a->tv_sec)) return r;
  18     return b->tv_usec - a->tv_usec;
  19
  20 }
  21
  22 static void insert_timer(Timer *self)
  23 {
  24     GSList *it;
  25     for (it = timers; it != NULL; it = it->next) {
  26         Timer *t = it->data;
  27         if (timecompare(&self->timeout, &t->timeout) <= 0) {
  28             timers = g_slist_insert_before(timers, it, self);
  29             break;
  30         }
  31     }
  32     if (it == NULL) /* didnt fit anywhere in the list */
  33         timers = g_slist_append(timers, self);
  34 }
  35
  36 void timer_startup()
  37 {
  38     g_get_current_time(&now);
  39     timers = NULL;
  40 }
  41
  42 void timer_shutdown()
  43 {
  44     GSList *it;
  45     for (it = timers; it != NULL; it = it->next) {
  46         g_free(it->data);
  47     }
  48     g_slist_free(timers);
  49     timers = NULL;
  50 }
  51
  52 Timer *timer_start(long delay, TimeoutHandler cb, void *data)
  53 {
  54     Timer *self = g_new(Timer, 1);
  55     self->delay = delay;
  56     self->action = cb;
  57     self->data = data;
  58     self->del_me = FALSE;
  59     self->last = self->timeout = now;
  60     g_time_val_add(&self->timeout, delay);
  61
  62     insert_timer(self);
  63
  64     return self;
  65 }
  66
  67 void timer_stop(Timer *self)
  68 {
  69     self->del_me = TRUE;
  70 }
  71
  72 /* find the time to wait for the nearest timeout */
  73 static gboolean nearest_timeout_wait(GTimeVal *tm)
  74 {
  75   if (timers == NULL)
  76     return FALSE;
  77
  78   tm->tv_sec = NEAREST_TIMEOUT.tv_sec - now.tv_sec;
  79   tm->tv_usec = NEAREST_TIMEOUT.tv_usec - now.tv_usec;
  80
  81   while (tm->tv_usec < 0) {
  82     tm->tv_usec += G_USEC_PER_SEC;
  83     tm->tv_sec--;
  84   }
  85   tm->tv_sec += tm->tv_usec / G_USEC_PER_SEC;
  86   tm->tv_usec %= G_USEC_PER_SEC;
  87   if (tm->tv_sec < 0)
  88     tm->tv_sec = 0;
  89
  90   return TRUE;
  91 }
  92
  93
  94 void timer_dispatch(GTimeVal **wait)
  95 {
  96     g_get_current_time(&now);
  97
  98     while (timers != NULL) {
  99         Timer *curr = timers->data; /* get the top element */
 100         /* since timer_stop doesn't actually free the timer, we have to do our
 101            real freeing in here.
 102         */
 103         if (curr->del_me) {
 104             timers = g_slist_delete_link(timers, timers); /* delete the top */
 105             g_free(curr);
 106             continue;
 107         }
 108
 109         /* the queue is sorted, so if this timer shouldn't fire, none are
 110            ready */
 111         if (timecompare(&NEAREST_TIMEOUT, &now) <= 0)
 112             break;
 113
 114         /* we set the last fired time to delay msec after the previous firing,
 115            then re-insert.  timers maintain their order and may trigger more
 116            than once if they've waited more than one delay's worth of time.
 117         */
 118         timers = g_slist_delete_link(timers, timers);
 119         g_time_val_add(&curr->last, curr->delay);
 120         curr->action(curr->data);
 121         g_time_val_add(&curr->timeout, curr->delay);
 122         insert_timer(curr);
 123
 124         /* if at least one timer fires, then don't wait on X events, as there
 125            may already be some in the queue from the timer callbacks.
 126         */
 127         ret_wait.tv_sec = ret_wait.tv_usec = 0;
 128         *wait = &ret_wait;
 129         return;
 130     }
 131
 132     if (nearest_timeout_wait(&ret_wait))
 133         *wait = &ret_wait;
 134     else
 135         *wait = NULL;
 136 }