Function least_cost

devtools/route.c:13–62

#include <stdio.h>

static struct route_hop *least_cost(struct gossmap *map,
				    struct gossmap_node *src,
				    struct gossmap_node *dst)
{
	const struct dijkstra *dij;
	u32 srcidx = gossmap_node_idx(map, src);
	/* 10ksat, budget is 0.5% */
	const struct amount_msat sent = AMOUNT_MSAT(10000000);
	const struct amount_msat budget = amount_msat_div(sent, 200);
	struct amount_msat fee;
	const u32 riskfactor = 10;
	/* Max distance is 20 */
	const u32 distance_budget = ROUTING_MAX_HOPS;
	struct amount_msat maxcost;
	struct route_hop *path;
	struct timemono tstart, tstop;

	setup_locale();
	setup_tmpctx();

	tstart = time_mono();
	dij = dijkstra(tmpctx, map, dst,
		       sent, riskfactor, route_can_carry,
		       route_score_cheaper, NULL);
	tstop = time_mono();

	printf("# Time to find route: %"PRIu64" usec\n",
	       time_to_usec(timemono_between(tstop, tstart)));

	if (dijkstra_distance(dij, srcidx) > distance_budget) {
		printf("failed (too far)\n");
		return NULL;
	}
	if (!amount_msat_add(&maxcost, sent, budget))
		abort();
	path = route_from_dijkstra(map, map, dij, src, sent, 0);
	if (amount_msat_greater(path[0].amount, maxcost)) {
		printf("failed (too expensive)\n");
		return tal_free(path);
	}

	printf("# path length %zu\n", tal_count(path));
	/* We don't pay fee on first hop! */
	if (!amount_msat_sub(&fee, path[0].amount, sent))
		abort();
	printf("# path fee %s\n",
	       type_to_string(tmpctx, struct amount_msat, &fee));
	tal_free(dij);
	return path;
}

int main(int argc, char *argv[])
{