gossipd: simplify seeker startup.

Most nodes don't really care about exact timestamps on gossip filters,
so just keep a flag on whether we have anything in the gossip_store,
and use that to determine whether we ask peers for everything.

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

gossipd/gossipd.c

@@ -498,6 +498,9 @@ static void handle_recv_gossip(struct daemon *daemon, const u8 *outermsg)
 handled_msg:
 	if (err)
 		queue_peer_msg(peer->daemon, &peer->id, take(err));
+	else
+		/* Some peer gave us gossip, so we're not at zero. */
+		peer->daemon->gossip_store_populated = true;
 }
 
 /*~ connectd's input handler is very simple. */
@@ -674,7 +677,6 @@ bool timestamp_reasonable(const struct daemon *daemon, u32 timestamp)
 static void gossip_init(struct daemon *daemon, const u8 *msg)
 {
 	u32 *dev_gossip_time;
-	u32 timestamp;
 
 	if (!fromwire_gossipd_init(daemon, msg,
 				     &chainparams,
@@ -696,14 +698,9 @@ static void gossip_init(struct daemon *daemon, const u8 *msg)
 
 	daemon->rstate = new_routing_state(daemon, daemon);
 
-	/* Load stored gossip messages, get last modified time of file */
-	timestamp = gossip_store_load(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;
+	/* Load stored gossip messages (FIXME: API sucks)*/
+	daemon->gossip_store_populated =
+		(gossip_store_load(daemon->rstate->gs) != 0);
 
 	/* Start the twice- weekly refresh timer. */
 	notleak(new_reltimer(&daemon->timers, daemon,

gossipd/gossipd.h

@@ -65,6 +65,9 @@ struct daemon {
 	/* Features lightningd told us to set. */
 	struct feature_set *our_features;
 
+	/* Was there anything in the gossip store at startup? */
+	bool gossip_store_populated;
+
 	/* Override local time for gossip messages */
 	struct timeabs *dev_gossip_time;
 

gossipd/routing.c

@@ -242,7 +242,6 @@ struct routing_state *new_routing_state(const tal_t *ctx,
 	rstate->daemon = daemon;
 	rstate->nodes = new_node_map(rstate);
 	rstate->gs = gossip_store_new(daemon);
-	rstate->last_timestamp = 0;
 	rstate->dying_channels = tal_arr(rstate, struct dying_channel, 0);
 
 	rstate->pending_cannouncements = tal(rstate, struct pending_cannouncement_map);
@@ -1375,9 +1374,6 @@ bool routing_add_channel_update(struct routing_state *rstate,
 		hc->rgraph.index
 			= gossip_store_add(rstate->gs, update, timestamp,
 					   zombie, spam, dying, NULL);
-		if (hc->bcast.timestamp > rstate->last_timestamp
-		    && hc->bcast.timestamp < time_now().ts.tv_sec)
-			rstate->last_timestamp = hc->bcast.timestamp;
 		if (!spam)
 			hc->bcast.index = hc->rgraph.index;
 
@@ -1794,9 +1790,6 @@ bool routing_add_node_announcement(struct routing_state *rstate,
 		node->rgraph.index
 			= gossip_store_add(rstate->gs, msg, timestamp,
 					   false, spam, false, NULL);
-		if (node->bcast.timestamp > rstate->last_timestamp
-		    && node->bcast.timestamp < time_now().ts.tv_sec)
-			rstate->last_timestamp = node->bcast.timestamp;
 		if (!spam)
 			node->bcast.index = node->rgraph.index;
 

gossipd/routing.h

@@ -200,9 +200,6 @@ struct routing_state {
 	 * checks if we get another announcement for the same scid. */
 	struct txout_failures *txf;
 
-	/* Highest timestamp of gossip we accepted (before now) */
-	u32 last_timestamp;
-
 	/* Channels which are closed, but we're waiting 12 blocks */
 	struct dying_channel *dying_channels;
 };

gossipd/seeker.c

@@ -209,17 +209,21 @@ static void disable_gossip_stream(struct seeker *seeker, struct peer *peer)
 
 static void enable_gossip_stream(struct seeker *seeker, struct peer *peer)
 {
-	/* 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;
+	u32 start;
 	u8 *msg;
 
-	if (start > polltime)
-		start -= polltime;
-	else
+	/* Modern timestamp_filter is a trinary: 0 = all, FFFFFFFF = none,
+	 * other = from now on */
+	if (seeker->daemon->gossip_store_populated) {
+		/* Just in case they care */
+		start = time_now().ts.tv_sec - GOSSIP_SEEKER_INTERVAL(seeker) * 10;
+	} else {
 		start = 0;
+	}
 
-	status_peer_debug(&peer->id, "seeker: starting gossip");
+	status_peer_debug(&peer->id, "seeker: starting gossip (%s)",
+			  seeker->daemon->gossip_store_populated
+			  ? "streaming" : "EVERTHING");
 
 	/* This is allowed even if they don't understand it (odd) */
 	msg = towire_gossip_timestamp_filter(NULL,