gossip: instead of refresh interval, have routing know prune_timeout.

This is twice the 'update_channel_interval' we get handed.

We delete the non-existent channel_add_connection and delete_connection
declarations from the header too.

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

gossipd/gossip.c

@@ -83,8 +83,6 @@ struct daemon {
 
 	/* To make sure our node_announcement timestamps increase */
 	u32 last_announce_timestamp;
-
-	u32 update_channel_interval;
 };
 
 /* Peers we're trying to reach. */
@@ -1331,19 +1329,19 @@ static void gossip_send_keepalive_update(struct routing_state *rstate,
 
 }
 
-static void gossip_prune_network(struct daemon *daemon)
+static void gossip_refresh_network(struct daemon *daemon)
 {
 	u64 now = time_now().ts.tv_sec;
 	struct node_map_iter it;
 	/* Anything below this highwater mark ought to be pruned */
-	s64 highwater = now - 2*daemon->update_channel_interval;
+	s64 highwater = now - daemon->rstate->prune_timeout;
 	struct node *n;
 	const tal_t *pruned = tal_tmpctx(daemon);
 
 	/* Schedule next run now */
 	new_reltimer(&daemon->timers, daemon,
-		     time_from_sec(daemon->update_channel_interval/2),
-		     gossip_prune_network, daemon);
+		     time_from_sec(daemon->rstate->prune_timeout/4),
+		     gossip_refresh_network, daemon);
 
 	/* Find myself in the network */
 	n = get_node(daemon->rstate, &daemon->id);
@@ -1361,7 +1359,7 @@ static void gossip_prune_network(struct daemon *daemon)
 				continue;
 			}
 
-			if (now - nc->last_timestamp < daemon->update_channel_interval) {
+			if (now - nc->last_timestamp < daemon->rstate->prune_timeout / 2) {
 				/* No need to send a keepalive update message */
 				continue;
 			}
@@ -1522,21 +1520,24 @@ static struct io_plan *gossip_init(struct daemon_conn *master,
 {
 	struct bitcoin_blkid chain_hash;
 	u16 port;
+	u32 update_channel_interval;
 
 	if (!fromwire_gossipctl_init(
 		daemon, msg, &daemon->broadcast_interval, &chain_hash,
 		&daemon->id, &port, &daemon->globalfeatures,
 		&daemon->localfeatures, &daemon->wireaddrs, daemon->rgb,
-		daemon->alias, &daemon->update_channel_interval)) {
+		daemon->alias, &update_channel_interval)) {
 		master_badmsg(WIRE_GOSSIPCTL_INIT, msg);
 	}
-	daemon->rstate = new_routing_state(daemon, &chain_hash, &daemon->id);
+	/* Prune time is twice update time */
+	daemon->rstate = new_routing_state(daemon, &chain_hash, &daemon->id,
+					   update_channel_interval * 2);
 
 	setup_listeners(daemon, port);
 
 	new_reltimer(&daemon->timers, daemon,
-		     time_from_sec(daemon->update_channel_interval/2),
-		     gossip_prune_network, daemon);
+		     time_from_sec(daemon->rstate->prune_timeout/4),
+		     gossip_refresh_network, daemon);
 
 	return daemon_conn_read_next(master->conn, master);
 }

gossipd/routing.c

@@ -94,13 +94,15 @@ static struct node_map *empty_node_map(const tal_t *ctx)
 
 struct routing_state *new_routing_state(const tal_t *ctx,
 					const struct bitcoin_blkid *chain_hash,
-					const struct pubkey *local_id)
+					const struct pubkey *local_id,
+					u32 prune_timeout)
 {
 	struct routing_state *rstate = tal(ctx, struct routing_state);
 	rstate->nodes = empty_node_map(rstate);
 	rstate->broadcasts = new_broadcast_state(rstate);
 	rstate->chain_hash = *chain_hash;
 	rstate->local_id = *local_id;
+	rstate->prune_timeout = prune_timeout;
 	list_head_init(&rstate->pending_cannouncement);
 	uintmap_init(&rstate->channels);
 
@@ -242,9 +244,9 @@ static struct node_connection *new_node_connection(struct routing_state *rstate,
 	c->unroutable_until = 0;
 	c->active = false;
 	c->flags = idx;
-	/* We haven't seen channel_update: give it an hour before we prune,
+	/* We haven't seen channel_update: make it halfway to prune time,
 	 * which should be older than any update we'd see. */
-	c->last_timestamp = time_now().ts.tv_sec - (1209600 - 3600);
+	c->last_timestamp = time_now().ts.tv_sec - rstate->prune_timeout/2;
 
 	/* Hook it into in/out arrays. */
 	chan->connections[idx] = c;

gossipd/routing.h

@@ -157,6 +157,9 @@ struct routing_state {
 	/* Our own ID so we can identify local channels */
 	struct pubkey local_id;
 
+	/* How old does a channel have to be before we prune it? */
+	u32 prune_timeout;
+
         /* A map of channels indexed by short_channel_ids */
 	UINTMAP(struct routing_channel*) channels;
 };
@@ -177,7 +180,8 @@ struct route_hop {
 
 struct routing_state *new_routing_state(const tal_t *ctx,
 					const struct bitcoin_blkid *chain_hash,
-					const struct pubkey *local_id);
+					const struct pubkey *local_id,
+					u32 prune_timeout);
 
 struct routing_channel *new_routing_channel(struct routing_state *rstate,
 					    const struct short_channel_id *scid,
@@ -236,12 +240,7 @@ void routing_failure(struct routing_state *rstate,
 void mark_channel_unroutable(struct routing_state *rstate,
 			     const struct short_channel_id *channel);
 
-/* Add the connection to the channel */
-void channel_add_connection(struct routing_state *rstate,
-			    struct routing_channel *chan,
-			    struct node_connection *nc);
-
-void delete_connection(struct routing_channel *chan, int idx);
+void route_prune(struct routing_state *rstate);
 
 /* Utility function that, given a source and a destination, gives us
  * the direction bit the matching channel should get */

gossipd/test/run-bench-find_route.c

@@ -191,7 +191,7 @@ int main(int argc, char *argv[])
 	secp256k1_ctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY
 						 | SECP256K1_CONTEXT_SIGN);
 
-	rstate = new_routing_state(ctx, &zerohash, &me);
+	rstate = new_routing_state(ctx, &zerohash, &me, 0);
 	opt_register_noarg("--perfme", opt_set_bool, &perfme,
 			   "Run perfme-start and perfme-stop around benchmark");
 

gossipd/test/run-find_route-specific.c

@@ -110,7 +110,7 @@ int main(void)
 			   strlen("02ea622d5c8d6143f15ed3ce1d501dd0d3d09d3b1c83a44d0034949f8a9ab60f06"),
 			   &c);
 
-	rstate = new_routing_state(ctx, &zerohash, &a);
+	rstate = new_routing_state(ctx, &zerohash, &a, 0);
 
 	/* [{'active': True, 'short_id': '6990:2:1/1', 'fee_per_kw': 10, 'delay': 5, 'flags': 1, 'destination': '0230ad0e74ea03976b28fda587bb75bdd357a1938af4424156a18265167f5e40ae', 'source': '02ea622d5c8d6143f15ed3ce1d501dd0d3d09d3b1c83a44d0034949f8a9ab60f06', 'last_update': 1504064344}, */
 	nc = get_or_make_connection(rstate, &c, &b, "6990:2:1");

gossipd/test/run-find_route.c

@@ -146,7 +146,7 @@ int main(void)
 						 | SECP256K1_CONTEXT_SIGN);
 
 	memset(&tmp, 'a', sizeof(tmp));
-	rstate = new_routing_state(ctx, &zerohash, &a);
+	rstate = new_routing_state(ctx, &zerohash, &a, 0);
 
 	pubkey_from_privkey(&tmp, &a);
 	new_node(rstate, &a);

tests/test_lightningd.py

@@ -1854,7 +1854,7 @@ class LightningDTests(BaseLightningDTests):
         assert [c['active'] for c in l2.rpc.listchannels()['channels']] == [True, True]
         assert [c['public'] for c in l2.rpc.listchannels()['channels']] == [True, True]
 
-    @unittest.skip("Temporarily broken for short pruning times")
+    @unittest.skipIf(not DEVELOPER, "needs DEVELOPER=1 for --dev-broadcast-interval")
     def test_gossip_pruning(self):
         """ Create channel and see it being updated in time before pruning
         """
@@ -1889,6 +1889,12 @@ class LightningDTests(BaseLightningDTests):
         ])
 
         # Now kill l3, so that l2 and l1 can prune it from their view after 10 seconds
+
+        # FIXME: This sleep() masks a real bug: that channeld sends a
+        # channel_update message (to disable the channel) with same
+        # timestamp as the last keepalive, and thus is ignored.  The minimal
+        # fix is to backdate the keepalives 1 second, but maybe we should
+        # simply have gossipd generate all updates?
         time.sleep(1)
         l3.stop()