/* $Id: element.c,v 1.7 2004/03/25 00:10:21 jmuelmen Exp $ */

#include "scheduler.h"
#include "queue.h"
#include "parse.h"

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <pthread.h>

queue_el_t *queue_el_create (func_t f, value_t *argv, int argc, 
			     value_t *ret) 
{
     int i;
     queue_el_t *l = malloc(sizeof(queue_el_t));
     l->f = f;
     /* copy the arguments */
     for (i = 0; i < argc; ++i)
	  l->argv[i] = argv[i];
     l->argc = argc;
     l->ret = ret;

     return l;
}

void queue_el_destroy (queue_el_t *l)
{
     free(l);
}

/* thread function that does the actual evaluating */
void *queue_el_execute (void *v) 
{
     queue_el_t *l = (queue_el_t *)v;
     value_t ret = l->f(l->argv, l->argc);

    /* copy the return value into the right place */
     pthread_mutex_lock(&l->ret->mut);
     value_copy(l->ret, &ret);
     l->ret->returned = 1;
     pthread_mutex_unlock(&l->ret->mut);
     /* then signal that the function call has returned */
     pthread_cond_signal(&l->ret->has_returned);
     queue_el_destroy(l);

     return NULL;
}

void queue_el_process (queue_el_t *l)
{
     /* detach a thread that does the actual evaluating; return immediately */
     int err;
     pthread_t proc_thr;
     
     err = pthread_create(&proc_thr, NULL, queue_el_execute, l);
     if (err)
	  perror("creating queue element evaluation thread");
     err = pthread_detach(proc_thr);  
     if (err)  
    	  perror("detaching queue element evaluation thread");  
}