gossip: Have the broadcast_state track its message count

This is far more precise than bolting on the stale tracking in the
`gossip_store`.

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

gossipd/broadcast.c

@@ -27,6 +27,7 @@ struct broadcast_state *new_broadcast_state(tal_t *ctx)
 	uintmap_init(&bstate->broadcasts);
 	/* Skip 0 because we initialize peers with 0 */
 	bstate->next_index = 1;
+	bstate->count = 0;
 	return bstate;
 }
 
@@ -43,6 +44,7 @@ static void destroy_queued_message(struct queued_message *msg,
 				   struct broadcast_state *bstate)
 {
 	broadcast_del(bstate, msg->index, msg->payload);
+	bstate->count--;
 }
 
 static struct queued_message *new_queued_message(const tal_t *ctx,
@@ -58,6 +60,7 @@ static struct queued_message *new_queued_message(const tal_t *ctx,
 	msg->timestamp = timestamp;
 	uintmap_add(&bstate->broadcasts, index, msg);
 	tal_add_destructor2(msg, destroy_queued_message, bstate);
+	bstate->count++;
 	return msg;
 }
 

gossipd/broadcast.h

@@ -12,6 +12,7 @@
 struct broadcast_state {
 	u64 next_index;
 	UINTMAP(struct queued_message *) broadcasts;
+	size_t count;
 };
 
 struct broadcast_state *new_broadcast_state(tal_t *ctx);