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) && rp->alarm <= now){
  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
  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 && p->alarm <= now)
  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
  71         qlock(&alarms);
  72         l = &alarms.head;
  73         for(f = *l; f; f = f->palarm) {
  74                 if(up == f){
  75                         *l = f->palarm;
  76                         break;
  77                 }
  78                 l = &f->palarm;
  79         }
  80
  81         up->palarm = 0;
  82         if(alarms.head) {
  83                 l = &alarms.head;
  84                 for(f = *l; f; f = f->palarm) {
  85                         if(f->alarm > when) {
  86                                 up->palarm = f;
  87                                 *l = up;
  88                                 goto done;
  89                         }
  90                         l = &f->palarm;
  91                 }
  92                 *l = up;
  93         }
  94         else
  95                 alarms.head = up;
  96 done:
  97         up->alarm = when;
  98         qunlock(&alarms);
  99
 100         return old;
 101 }