closestnode.b

件主要用于帮助计算机爱好者学习蚁群算法时做有关蚁群算法的试验。蚁群算法作为一种优秀的新兴的算法

Measurement closest(double beta, Node t[]) {
	Measurement self = get_distance_tcp(t, -1);
	double avg_lat = array_avg(self.distance);
	double min_lat = array_min(self.distance);
	double max_lat = array_max(self.distance);
	Node ring_m[] = array_intersect(
		ring_ge((1.0 - beta) * min_lat), ring_le((1.0 + beta) * max_lat));
	if (array_size(ring_m) == 0) {
		return self;
	}
	Measurement r_lat[] = get_distance_tcp(ring_m, t, 
		ceil((2.0 * beta + 1.0) * max_lat));
	int min_index = -1; 
	min_lat = avg_lat;
	for (int i = 0; i < array_size(r_lat); i = i + 1) { 
		double cur_lat = array_avg(r_lat[i].distance);
		if (cur_lat < min_lat) {
			min_index = i;
			min_lat = cur_lat; 
		}
	}
	if (min_index == -1) {
		return self;
	}
	Measurement min_n = r_lat[min_index];	
	if (min_n.addr != 0 && min_lat < (avg_lat * beta)) {
		Measurement ret_n = rpc(ring_m[min_index], closest, beta, t);
		if (ret_n.addr != 0) {
			return ret_n;
		}
	}	
	return min_n;
}

int main() {
	Node t1 = {dns_lookup("www.cs.berkeley.edu"), 80, 0, 0};
	Node ts[] = {t1};
	Node e = {dns_lookup("planetlab1.cs.cornell.edu"), 3964, 0, 0};	
	Measurement r = rpc(e, closest, 0.5, ts);
	if (r.addr == 0) {
		r.addr = e.addr;
		r.port = e.port;
	}
	print("Closest node is ");
	println(dns_addr(r.addr));
	for (int i = 0; i < array_size(r.distance); i = i + 1) {
		print("--> ");
		print(r.distance[i]);
		print(" from ");
		println(dns_addr(ts[i].addr));
	}
	return 0;
}