sys/src/9/port/alarm.c

   1 #include        "u.h"
   2 #include        "../port/lib.h"
   3 #include        "mem.h"
   4 #include        "dat.h"
   5 #include        "fns.h"
   6
   7 static Alarms   alarms;
   8 static Rendez   alarmr;
   9
  10 void
  11 alarmkproc(void*)
  12 {
  13         Proc *rp;
  14         ulong now, when;
  15
  16         while(waserror())
  17                 ;
  18
  19         for(;;){
  20                 now = MACHP(0)->ticks;
  21                 qlock(&alarms);
  22                 for(rp = alarms.head; rp != nil; rp = rp->palarm){
  23                         if((when = rp->alarm) == 0)
  24                                 continue;
  25                         if((long)(now - when) < 0)
  26                                 break;
  27                         if(!canqlock(&rp->debug))
  28                                 break;
  29                         if(rp->alarm != 0){
  30                                 postnote(rp, 0, "alarm", NUser);
  31                                 rp->alarm = 0;
  32                         }
  33                         qunlock(&rp->debug);
  34                 }
  35                 alarms.head = rp;
  36                 qunlock(&alarms);
  37
  38                 sleep(&alarmr, return0, 0);
  39         }
  40 }
  41
  42 /*
  43  *  called every clock tick on cpu0
  44  */
  45 void
  46 checkalarms(void)
  47 {
  48         Proc *p;
  49         ulong now, when;
  50
  51         p = alarms.head;
  52         if(p != nil){
  53                 now = MACHP(0)->ticks;
  54                 when = p->alarm;
  55                 if(when == 0 || (long)(now - when) >= 0)
  56                         wakeup(&alarmr);
  57         }
  58 }
  59
  60 ulong
  61 procalarm(ulong time)
  62 {
  63         Proc **l, *f;
  64         ulong when, old;
  65
  66         when = MACHP(0)->ticks;
  67         old = up->alarm;
  68         if(old) {
  69                 old -= when;
  70                 if((long)old > 0)
  71                         old = tk2ms(old);
  72                 else
  73                         old = 0;
  74         }
  75         if(time == 0) {
  76                 up->alarm = 0;
  77                 return old;
  78         }
  79         when += ms2tk(time);
  80         if(when == 0)
  81                 when = 1;
  82
  83         qlock(&alarms);
  84         l = &alarms.head;
  85         for(f = *l; f; f = f->palarm) {
  86                 if(up == f){
  87                         *l = f->palarm;
  88                         break;
  89                 }
  90                 l = &f->palarm;
  91         }
  92         l = &alarms.head;
  93         for(f = *l; f; f = f->palarm) {
  94                 time = f->alarm;
  95                 if(time != 0 && (long)(time - when) >= 0)
  96                         break;
  97                 l = &f->palarm;
  98         }
  99         up->palarm = f;
 100         *l = up;
 101         up->alarm = when;
 102         qunlock(&alarms);
 103
 104         return old;
 105 }