Function count_possible_destinations

devtools/topology.c:123–155

What nodes can n reach without going through exclude? */

/* What nodes can n reach without going through exclude? */
static size_t count_possible_destinations(const struct gossmap *map,
					  struct gossmap_node *start,
					  struct gossmap_node *exclude,
					  bool is_first_node)
{
	const struct dijkstra *dij;
	size_t distance_budget, num;

	dij = dijkstra(tmpctx, map, start, AMOUNT_MSAT(0), 0,
		       channel_usable_from_excl, route_score_shorter, exclude);

	if (is_first_node)
		distance_budget = ROUTING_MAX_HOPS - 1;
	else
		distance_budget = ROUTING_MAX_HOPS - 2;

	assert(dijkstra_distance(dij, gossmap_node_idx(map, start)) == 0);
	assert(dijkstra_distance(dij, gossmap_node_idx(map, exclude)) == UINT_MAX);

	num = 0;
	for (struct gossmap_node *n = gossmap_first_node(map);
	     n;
	     n = gossmap_next_node(map, n)) {
		if (dijkstra_distance(dij, gossmap_node_idx(map, n)) <= distance_budget)
			num++;
	}

	/* Now double-check with flood-fill. */
	bool *visited = tal_arrz(tmpctx, bool, gossmap_max_node_idx(map));
	visit(map, start, exclude, visited);
	assert(memcount(visited, tal_bytelen(visited), true) == num);
	return num;
}

static bool measure_least_cost(struct gossmap *map,
			       struct gossmap_node *src,