Subversion Repositories planix.SVN

#include "stdinc.h"
#include "dat.h"
#include "fns.h"
#include "error.h"

struct Periodic {
        VtLock *lk;
        int die;                /* flag: quit if set */
        void (*f)(void*);       /* call this each period */
        void *a;                /* argument to f */
        int msec;               /* period */
};

static void periodicThread(void *a);

Periodic *
periodicAlloc(void (*f)(void*), void *a, int msec)
{
        Periodic *p;

        p = vtMemAllocZ(sizeof(Periodic));
        p->lk = vtLockAlloc();
        p->f = f;
        p->a = a;
        p->msec = msec;
        if(p->msec < 10)
                p->msec = 10;

        vtThread(periodicThread, p);
        return p;
}

void
periodicKill(Periodic *p)
{
        if(p == nil)
                return;
        vtLock(p->lk);
        p->die = 1;
        vtUnlock(p->lk);
}

static void
periodicFree(Periodic *p)
{
        vtLockFree(p->lk);
        vtMemFree(p);
}

static void
periodicThread(void *a)
{
        Periodic *p = a;
        vlong t, ct, ts;                /* times in ms. */

        vtThreadSetName("periodic");

        ct = nsec() / 1000000;
        t = ct + p->msec;               /* call p->f at or after this time */

        for(;;){
                ts = t - ct;            /* ms. to next cycle's start */
                if(ts > 1000)
                        ts = 1000;      /* bound sleep duration */
                if(ts > 0)
                        sleep(ts);      /* wait for cycle's start */

                vtLock(p->lk);
                if(p->die){
                        vtUnlock(p->lk);
                        break;
                }
                ct = nsec() / 1000000;
                if(t <= ct){            /* due to call p->f? */
                        p->f(p->a);
                        ct = nsec() / 1000000;
                        while(t <= ct)  /* advance t to future cycle start */
                                t += p->msec;
                }
                vtUnlock(p->lk);
        }
        periodicFree(p);
}