gossipd: start streaming gossip from last gossip timestamp minus 10 minutes.

We assume that the time for gossip propagation is < 10 minutes, so by
going back that far from last gossip we won't miss anything,

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

gossipd/gossipd.c

@@ -816,9 +816,15 @@ static struct io_plan *gossip_init(struct io_conn *conn,
 					   dev_fast_gossip,
 					   dev_fast_gossip_prune);
 
-	/* Load stored gossip messages */
+	/* Load stored gossip messages, get last modified time of file */
 	timestamp = gossip_store_load(daemon->rstate, daemon->rstate->gs);
 
+	/* If last_timestamp was > modified time of file, reduce it.
+	 * Usually it's capped to "now", but in the reload case it needs to
+	 * be the gossip_store mtime. */
+	if (daemon->rstate->last_timestamp > timestamp)
+		daemon->rstate->last_timestamp = timestamp;
+
 	/* Now disable all local channels, they can't be connected yet. */
 	gossip_disable_local_channels(daemon);
 
@@ -832,7 +838,7 @@ static struct io_plan *gossip_init(struct io_conn *conn,
 			     gossip_refresh_network, daemon));
 
 	/* Fire up the seeker! */
-	daemon->seeker = new_seeker(daemon, timestamp);
+	daemon->seeker = new_seeker(daemon);
 
 	return daemon_conn_read_next(conn, daemon->master);
 }

gossipd/routing.c

@@ -298,6 +298,7 @@ struct routing_state *new_routing_state(const tal_t *ctx,
 	rstate->chainparams = chainparams;
 	rstate->local_id = *local_id;
 	rstate->local_channel_announced = false;
+	rstate->last_timestamp = 0;
 
 	pending_cannouncement_map_init(&rstate->pending_cannouncements);
 
@@ -2183,6 +2184,10 @@ bool routing_add_channel_update(struct routing_state *rstate,
 			= gossip_store_add(rstate->gs, update,
 					   hc->bcast.timestamp,
 					   NULL);
+		if (hc->bcast.timestamp > rstate->last_timestamp
+		    && hc->bcast.timestamp < time_now().ts.tv_sec)
+			rstate->last_timestamp = hc->bcast.timestamp;
+
 		peer_supplied_good_gossip(peer, 1);
 	}
 
@@ -2504,6 +2509,10 @@ bool routing_add_node_announcement(struct routing_state *rstate,
 			    WIRE_NODE_ANNOUNCEMENT);
 
 	node->bcast.timestamp = timestamp;
+	if (node->bcast.timestamp > rstate->last_timestamp
+	    && node->bcast.timestamp < time_now().ts.tv_sec)
+		rstate->last_timestamp = node->bcast.timestamp;
+
 	if (index)
 		node->bcast.index = index;
 	else {

gossipd/routing.h

@@ -292,6 +292,9 @@ struct routing_state {
         /* A map of local channels by short_channel_ids */
 	struct local_chan_map local_chan_map;
 
+	/* Highest timestamp of gossip we accepted (before now) */
+	u32 last_timestamp;
+
 #if DEVELOPER
 	/* Override local time for gossip messages */
 	struct timeabs *gossip_time;

gossipd/seeker.c

@@ -85,9 +85,6 @@ struct seeker {
 	/* Range of scid blocks we've probed. */
 	size_t scid_probe_start, scid_probe_end;
 
-	/* Timestamp of gossip store (or 0). */
-	u32 last_gossip_timestamp;
-
 	/* During startup, we ask a single peer for gossip. */
 	struct peer *random_peer_softref;
 
@@ -136,14 +133,13 @@ static void set_state_(struct seeker *seeker, enum seeker_state state,
 	seeker->state = state;
 }
 
-struct seeker *new_seeker(struct daemon *daemon, u32 timestamp)
+struct seeker *new_seeker(struct daemon *daemon)
 {
 	struct seeker *seeker = tal(daemon, struct seeker);
 
 	seeker->daemon = daemon;
 	scid_map_init(&seeker->unknown_scids);
 	stale_scid_map_init(&seeker->stale_scids);
-	seeker->last_gossip_timestamp = timestamp;
 	seeker->random_peer_softref = NULL;
 	for (size_t i = 0; i < ARRAY_SIZE(seeker->gossiper_softref); i++)
 		seeker->gossiper_softref[i] = NULL;
@@ -202,12 +198,15 @@ static void disable_gossip_stream(struct seeker *seeker, struct peer *peer)
 
 static void enable_gossip_stream(struct seeker *seeker, struct peer *peer)
 {
-	u32 start;
+	/* We seek some way back, to take into account propagation time */
+	const u32 polltime = GOSSIP_SEEKER_INTERVAL(seeker) * 10;
+	u32 start = seeker->daemon->rstate->last_timestamp;
 	u8 *msg;
 
-	/* FIXME: gets the last minute of gossip, works around our current
-	 * lack of discovery if we're missing gossip. */
-	start = time_now().ts.tv_sec - 60;
+	if (start > polltime)
+		start -= polltime;
+	else
+		start = 0;
 
 	status_debug("seeker: starting gossip from %s",
 		     type_to_string(tmpctx, struct node_id, &peer->id));
@@ -265,23 +264,8 @@ static struct short_channel_id *unknown_scids_arr(const tal_t *ctx,
 /* We have selected this peer to stream us startup gossip */
 static void peer_gossip_startup(struct seeker *seeker, struct peer *peer)
 {
-	const u32 polltime = GOSSIP_SEEKER_INTERVAL(seeker);
-	u8 *msg;
-	u32 start;
-
-	if (seeker->last_gossip_timestamp < polltime)
-		start = 0;
-	else
-		start = seeker->last_gossip_timestamp - polltime;
-
 	selected_peer(seeker, peer);
-
-	status_debug("seeker: startup gossip from t=%u from %s",
-		     start, type_to_string(tmpctx, struct node_id, &peer->id));
-	msg = towire_gossip_timestamp_filter(NULL,
-					     &peer->daemon->chain_hash,
-					     start, UINT32_MAX);
-	queue_peer_msg(peer, take(msg));
+	normal_gossip_start(seeker, peer);
 }
 
 static bool peer_has_gossip_queries(const struct peer *peer)

gossipd/seeker.h

@@ -6,7 +6,7 @@ struct daemon;
 struct peer;
 struct short_channel_id;
 
-struct seeker *new_seeker(struct daemon *daemon, u32 timestamp);
+struct seeker *new_seeker(struct daemon *daemon);
 
 void query_unknown_channel(struct daemon *daemon,
 			   struct peer *peer,