devtool/route: simple routing tool and benchmark.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

devtools/Makefile

@@ -1,6 +1,6 @@
 DEVTOOLS_SRC := devtools/gen_print_wire.c devtools/gen_print_onion_wire.c devtools/print_wire.c
 DEVTOOLS_OBJS := $(DEVTOOLS_SRC:.c=.o)
-DEVTOOLS := devtools/bolt11-cli devtools/decodemsg devtools/onion devtools/dump-gossipstore devtools/gossipwith devtools/create-gossipstore devtools/mkcommit devtools/mkfunding devtools/mkclose devtools/mkgossip devtools/mkencoded devtools/checkchannels devtools/mkquery devtools/lightning-checkmessage devtools/topology
+DEVTOOLS := devtools/bolt11-cli devtools/decodemsg devtools/onion devtools/dump-gossipstore devtools/gossipwith devtools/create-gossipstore devtools/mkcommit devtools/mkfunding devtools/mkclose devtools/mkgossip devtools/mkencoded devtools/checkchannels devtools/mkquery devtools/lightning-checkmessage devtools/topology devtools/route
 ifeq ($(EXPERIMENTAL_FEATURES),1)
 DEVTOOLS += devtools/blindedpath
 endif
@@ -93,6 +93,8 @@ devtools/mkquery: $(DEVTOOLS_COMMON_OBJS) $(CCAN_OBJS) $(BITCOIN_OBJS) wire/from
 
 devtools/lightning-checkmessage: $(DEVTOOLS_COMMON_OBJS) $(CCAN_OBJS) $(BITCOIN_OBJS) wire/fromwire.o wire/towire.o devtools/lightning-checkmessage.o
 
+devtools/route: $(DEVTOOLS_COMMON_OBJS) $(CCAN_OBJS) $(BITCOIN_OBJS) wire/fromwire.o wire/towire.o wire/tlvstream.o common/gossmap.o common/random_select.o common/route.o common/dijkstra.o devtools/clean_topo.o devtools/route.o
+
 devtools/topology: $(DEVTOOLS_COMMON_OBJS) $(CCAN_OBJS) $(BITCOIN_OBJS) wire/fromwire.o wire/towire.o wire/tlvstream.o common/gossmap.o common/random_select.o common/dijkstra.o common/route.o devtools/clean_topo.o devtools/topology.o
 
 # Make sure these depend on everything.

devtools/route.c

@@ -0,0 +1,165 @@
+#include <ccan/err/err.h>
+#include <ccan/opt/opt.h>
+#include <ccan/time/time.h>
+#include <common/amount.h>
+#include <common/dijkstra.h>
+#include <common/gossmap.h>
+#include <common/node_id.h>
+#include <common/pseudorand.h>
+#include <common/random_select.h>
+#include <common/route.h>
+#include <common/type_to_string.h>
+#include <devtools/clean_topo.h>
+#include <inttypes.h>
+#include <stdio.h>
+
+/* ->B->C->D.  D needs 100msat, each charges 10msat. */
+static struct amount_msat route_amount(struct route **path,
+				       size_t npath,
+				       struct amount_msat amount)
+{
+	if (npath == 0)
+		return amount;
+
+	amount = route_amount(path+1, npath-1, amount);
+	if (!amount_msat_add_fee(&amount,
+				 path[0]->c->half[path[0]->dir].base_fee,
+				 path[0]->c->half[path[0]->dir].proportional_fee))
+		abort();
+	return amount;
+}
+
+static struct route **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 **path;
+	struct timemono tstart, tstop;
+
+	setup_locale();
+	setup_tmpctx();
+
+	tstart = time_mono();
+	dij = dijkstra(tmpctx, map, dst,
+		       sent, riskfactor, route_can_carry,
+		       route_path_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();
+	if (amount_msat_greater(dijkstra_amount(dij, srcidx), maxcost)) {
+		printf("failed (too expensive)\n");
+		return NULL;
+	}
+
+	path = route_from_dijkstra(map, dij, src);
+	printf("# path length %zu\n", tal_count(path));
+	/* We don't pay fee on first hop! */
+	if (!amount_msat_sub(&fee,
+			     route_amount(path+1, tal_count(path)-1, sent),
+			     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[])
+{
+	struct timemono tstart, tstop;
+	struct gossmap_node *n, *dst;
+	struct gossmap *map;
+	struct node_id dstid;
+	bool clean_topology = false;
+
+	opt_register_noarg("--clean-topology", opt_set_bool, &clean_topology,
+			   "Clean up topology before run");
+	opt_register_noarg("-h|--help", opt_usage_and_exit,
+			   "<gossipstore> <srcid>|all <dstid>\n"
+			   "A routing test and benchmark program.",
+			   "Get usage information");
+	opt_parse(&argc, argv, opt_log_stderr_exit);
+	if (argc != 4)
+		opt_usage_exit_fail("Expect 3 arguments");
+
+	tstart = time_mono();
+	map = gossmap_load(NULL, argv[1]);
+	if (!map)
+		err(1, "Loading gossip store %s", argv[1]);
+	tstop = time_mono();
+
+	printf("# Time to load: %"PRIu64" msec\n",
+	       time_to_msec(timemono_between(tstop, tstart)));
+
+	if (clean_topology)
+		clean_topo(map, false);
+
+	if (!node_id_from_hexstr(argv[3], strlen(argv[3]), &dstid))
+		errx(1, "Bad dstid");
+	dst = gossmap_find_node(map, &dstid);
+	if (!dst)
+		errx(1, "Unknown destination node '%s'", argv[3]);
+
+	if (streq(argv[2], "all")) {
+		for (n = gossmap_first_node(map);
+		     n;
+		     n = gossmap_next_node(map, n)) {
+			struct node_id srcid, dstid;
+
+			gossmap_node_get_id(map, n, &srcid);
+			gossmap_node_get_id(map, dst, &dstid);
+			printf("# %s->%s\n",
+			       type_to_string(tmpctx, struct node_id, &srcid),
+			       type_to_string(tmpctx, struct node_id, &dstid));
+			tal_free(least_cost(map, n, dst));
+		}
+	} else {
+		struct route **path;
+		struct node_id srcid;
+
+		if (!node_id_from_hexstr(argv[2], strlen(argv[2]), &srcid))
+			errx(1, "Bad srcid");
+		n = gossmap_find_node(map, &srcid);
+		if (!n)
+			errx(1, "Unknown source node '%s'", argv[2]);
+		path = least_cost(map, n, dst);
+		if (!path)
+			exit(1);
+		for (size_t i = 0; i < tal_count(path); i++) {
+			struct gossmap_node *from, *to;
+			struct node_id fromid, toid;
+			struct short_channel_id scid;
+
+			from = gossmap_nth_node(map, path[i]->c, path[i]->dir);
+			to = gossmap_nth_node(map, path[i]->c, !path[i]->dir);
+			gossmap_node_get_id(map, from, &fromid);
+			gossmap_node_get_id(map, to, &toid);
+			scid = gossmap_chan_scid(map, path[i]->c);
+			printf("%s->%s via %s\n",
+			       type_to_string(tmpctx, struct node_id, &fromid),
+			       type_to_string(tmpctx, struct node_id, &toid),
+			       type_to_string(tmpctx, struct short_channel_id,
+					      &scid));
+		}
+	}
+
+	tal_free(map);
+}