ref: 224c03c17e5c664b1b5b8417d1940301d9fccfd5
dir: /time.c/
#include "inc.h"
/* taken from rio */
static Channel* ctimer; /* chan(Timer*)[100] */
static Timer *timer;
static uint
msec(void)
{
return nsec()/1000000;
}
void
timerstop(Timer *t)
{
t->next = timer;
timer = t;
}
void
timercancel(Timer *t)
{
t->cancel = TRUE;
}
static void
timerproc(void*)
{
int i, nt, na, dt, del;
Timer **t, *x;
uint old, new;
rfork(RFFDG);
threadsetname("TIMERPROC");
t = nil;
na = 0;
nt = 0;
old = msec();
for(;;){
sleep(1); /* will sleep minimum incr */
new = msec();
dt = new-old;
old = new;
if(dt < 0) /* timer wrapped; go around, losing a tick */
continue;
for(i=0; i<nt; i++){
x = t[i];
x->dt -= dt;
del = 0;
if(x->cancel){
timerstop(x);
del = 1;
}else if(x->dt <= 0){
/*
* avoid possible deadlock if client is
* now sending on ctimer
*/
if(nbsendul(x->c, 0) > 0)
del = 1;
}
if(del){
memmove(&t[i], &t[i+1], (nt-i-1)*sizeof t[0]);
--nt;
--i;
}
}
if(nt == 0){
x = recvp(ctimer);
gotit:
if(nt == na){
na += 10;
t = realloc(t, na*sizeof(Timer*));
if(t == nil)
abort();
}
t[nt++] = x;
old = msec();
}
if(nbrecv(ctimer, &x) > 0)
goto gotit;
}
}
void
timerinit(void)
{
ctimer = chancreate(sizeof(Timer*), 100);
proccreate(timerproc, nil, mainstacksize);
}
/*
* timeralloc() and timerfree() don't lock, so can only be
* called from the main proc.
*/
Timer*
timerstart(int dt)
{
Timer *t;
t = timer;
if(t)
timer = timer->next;
else{
t = emalloc(sizeof(Timer));
t->c = chancreate(sizeof(int), 0);
}
t->next = nil;
t->dt = dt;
t->cancel = FALSE;
sendp(ctimer, t);
return t;
}