daemon_conn: don't rely on outq_empty callback telling us to retry queue.

We had at least one bug caused by it not returning true when it had
queued something.  Instead, just re-check thq queue after it's called.

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

common/daemon_conn.c

@@ -18,9 +18,8 @@ struct daemon_conn {
 	/* Callback for incoming messages */
 	struct io_plan *(*recv)(struct io_conn *conn, const u8 *, void *);
 
-	/* Called whenever we've cleared the msg_out queue. If it returns
-	 * true, it has added packets to msg_out queue. */
-	bool (*outq_empty)(void *);
+	/* Called whenever we've cleared the msg_out queue. */
+	void (*outq_empty)(void *);
 
 	/* Arg for both callbacks. */
 	void *arg;
@@ -46,8 +45,14 @@ static struct io_plan *daemon_conn_write_next(struct io_conn *conn,
 {
 	const u8 *msg;
 
-again:
 	msg = msg_dequeue(dc->out);
+
+	/* If nothing in queue, give empty callback a chance to queue somthing */
+	if (!msg && dc->outq_empty) {
+		dc->outq_empty(dc->arg);
+		msg = msg_dequeue(dc->out);
+	}
+
 	if (msg) {
 		int fd = msg_extract_fd(msg);
 		if (fd >= 0) {
@@ -57,9 +62,6 @@ again:
 		}
 		return io_write_wire(conn, take(msg), daemon_conn_write_next,
 				     dc);
-	} else if (dc->outq_empty) {
-		if (dc->outq_empty(dc->arg))
-			goto again;
 	}
 	return msg_queue_wait(conn, dc->out, daemon_conn_write_next, dc);
 }
@@ -114,7 +116,7 @@ struct daemon_conn *daemon_conn_new_(const tal_t *ctx, int fd,
 				     struct io_plan *(*recv)(struct io_conn *,
 							     const u8 *,
 							     void *),
-				     bool (*outq_empty)(void *),
+				     void (*outq_empty)(void *),
 				     void *arg)
 {
 	struct daemon_conn *dc = tal(NULL, struct daemon_conn);

common/daemon_conn.h

@@ -21,14 +21,14 @@
 					     (recv), (arg), 	       \
 					     struct io_conn *,		\
 					     const u8 *),		\
-			 typesafe_cb(bool, void *,  (outq_empty), (arg)), \
+			 typesafe_cb(void, void *,  (outq_empty), (arg)), \
 			 arg)
 
 struct daemon_conn *daemon_conn_new_(const tal_t *ctx, int fd,
 				     struct io_plan *(*recv)(struct io_conn *,
 							     const u8 *,
 							     void *),
-				     bool (*outq_empty)(void *),
+				     void (*outq_empty)(void *),
 				     void *arg);
 
 /**

gossipd/gossipd.c

@@ -808,7 +808,7 @@ static void uniquify_node_ids(struct pubkey **ids)
 	tal_resize(ids, dst);
 }
 
-static bool create_next_scid_reply(struct peer *peer)
+static void maybe_create_next_scid_reply(struct peer *peer)
 {
 	struct routing_state *rstate = peer->daemon->rstate;
 	size_t i, num;
@@ -883,27 +883,24 @@ static bool create_next_scid_reply(struct peer *peer)
 							     &rstate->chain_hash,
 							     true);
 		queue_peer_msg(peer, take(end));
-		sent = true;
 		peer->scid_queries = tal_free(peer->scid_queries);
 		peer->scid_query_idx = 0;
 		peer->scid_query_nodes = tal_free(peer->scid_query_nodes);
 		peer->scid_query_nodes_idx = 0;
 	}
-
-	return sent;
 }
 
 /* If we're supposed to be sending gossip, do so now. */
-static bool maybe_queue_gossip(struct peer *peer)
+static void maybe_queue_gossip(struct peer *peer)
 {
 	const u8 *next;
 
 	if (peer->gossip_timer)
-		return false;
+		return;
 
 #if DEVELOPER
 	if (suppress_gossip)
-		return false;
+		return;
 #endif
 
 	next = next_broadcast(peer->daemon->rstate->broadcasts,
@@ -913,7 +910,7 @@ static bool maybe_queue_gossip(struct peer *peer)
 
 	if (next) {
 		queue_peer_msg(peer, next);
-		return true;
+		return;
 	}
 
 	/* Gossip is drained.  Wait for next timer. */
@@ -921,20 +918,18 @@ static bool maybe_queue_gossip(struct peer *peer)
 		= new_reltimer(&peer->daemon->timers, peer,
 			       time_from_msec(peer->daemon->broadcast_interval_msec),
 			       wake_gossip_out, peer);
-	return false;
 }
 
 /**
  * dump_gossip - catch the peer up with the latest gossip.
  */
-static bool dump_gossip(struct peer *peer)
+static void dump_gossip(struct peer *peer)
 {
 	/* Do we have scid query replies to send? */
-	if (create_next_scid_reply(peer))
-		return true;
+	maybe_create_next_scid_reply(peer);
 
-	/* Otherwise queue any gossip we want to send */
-	return maybe_queue_gossip(peer);
+	/* Queue any gossip we want to send */
+	maybe_queue_gossip(peer);
 }
 
 static void update_local_channel(struct daemon *daemon,