connectd: warn if we ignore peer incoming for longer than 5 seconds.

One reason why ping processing could be slow is that, once we receive
a message from the peer to send to a subdaemon, we don't listen for
others until we've drained that subdaemon queue entirely.

This can happens for reestablish: slow machines can take a while to
set that subdaemon up.

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

connectd/connectd.c

@@ -147,6 +147,7 @@ static struct peer *new_peer(struct daemon *daemon,
 	peer->sent_to_peer = NULL;
 	peer->urgent = false;
 	peer->draining = false;
+	peer->peer_in_lastmsg = -1;
 	peer->peer_outq = msg_queue_new(peer, false);
 	peer->last_recv_time = time_now();
 	peer->is_websocket = is_websocket;

connectd/connectd.h

@@ -96,6 +96,10 @@ struct peer {
 	/* Last time we received traffic */
 	struct timeabs last_recv_time;
 
+	/* How long have we been ignoring peer input? */
+	struct timemono peer_in_lasttime;
+	int peer_in_lastmsg;
+
 	/* Ratelimits for onion messages.  One token per msec. */
 	size_t onionmsg_incoming_tokens;
 	struct timemono onionmsg_last_incoming;

connectd/multiplex.c

@@ -1147,6 +1147,16 @@ static struct io_plan *write_to_subd(struct io_conn *subd_conn,
 
 		/* Tell them to read again. */
 		io_wake(&subd->peer->peer_in);
+		if (subd->peer->peer_in_lastmsg != -1) {
+			u64 msec = time_to_msec(timemono_between(time_mono(),
+								 subd->peer->peer_in_lasttime));
+			if (msec > 5000)
+				status_peer_broken(&subd->peer->id,
+						   "wake delay for %s: %"PRIu64"msec",
+						   peer_wire_name(subd->peer->peer_in_lastmsg),
+						   msec);
+			subd->peer->peer_in_lastmsg = -1;
+		}
 
 		/* Wait for them to wake us */
 		return msg_queue_wait(subd_conn, subd->outq,
@@ -1317,6 +1327,9 @@ static struct io_plan *read_body_from_peer_done(struct io_conn *peer_conn,
        }
 
        /* Wait for them to wake us */
+       peer->peer_in_lastmsg = type;
+       peer->peer_in_lasttime = time_mono();
+
        return io_wait(peer_conn, &peer->peer_in, next_read, peer);
 }