gossip: Remember which broadcast index the node_announcement had

Avoids searching for it in the uintmap.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

gossipd/routing.c

@@ -130,6 +130,7 @@ static struct node *new_node(struct routing_state *rstate,
 	n->out = tal_arr(n, struct node_connection *, 0);
 	n->alias = NULL;
 	n->node_announcement = NULL;
+	n->announcement_idx = 0;
 	n->last_timestamp = -1;
 	n->addresses = tal_arr(n, struct wireaddr, 0);
 	node_map_add(rstate->nodes, n);
@@ -1038,7 +1039,8 @@ void handle_node_announcement(
 
 	u8 *tag = tal_arr(tmpctx, u8, 0);
 	towire_pubkey(&tag, &node_id);
-	queue_broadcast(rstate->broadcasts,
+	replace_broadcast(rstate->broadcasts,
+			  &node->announcement_idx,
 			  WIRE_NODE_ANNOUNCEMENT,
 			  tag,
 			  serialized);

gossipd/routing.h

@@ -74,6 +74,9 @@ struct node {
 
 	/* Cached `node_announcement` we might forward to new peers. */
 	u8 *node_announcement;
+
+	/* What index does the announcement broadcast have? */
+	u64 announcement_idx;
 };
 
 const secp256k1_pubkey *node_map_keyof_node(const struct node *n);