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