subd: use peer log for messages (if any).

This makes much more sense when you ask for a specific peer's log.
Also, we put the peerid rather than pid ().

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

lightningd/peer_control.c

@@ -699,12 +699,10 @@ static void copy_to_parent_log(const char *prefix,
 			       const char *str,
 			       struct peer *peer)
 {
-	const char *idstr = type_to_string(peer, struct pubkey, &peer->id);
 	if (continued)
-		log_add(peer->ld->log, "Peer %s: ... %s", idstr, str);
+		log_add(peer->ld->log, "%s ... %s", prefix, str);
 	else
-		log_(peer->ld->log, level, "Peer %s: %s", idstr, str);
-	tal_free(idstr);
+		log_(peer->ld->log, level, "%s %s", prefix, str);
 }
 
 void populate_peer(struct lightningd *ld, struct peer *peer)

lightningd/subd.c

@@ -625,7 +625,16 @@ static struct subd *new_subd(struct lightningd *ld,
 		return tal_free(sd);
 	}
 	sd->ld = ld;
-	sd->log = new_log(sd, ld->log_book, "%s(%u):", name, sd->pid);
+	if (peer) {
+		/* FIXME: Use minimal unique pubkey prefix for logs! */
+		const char *idstr = type_to_string(peer, struct pubkey,
+						   &peer->id);
+		sd->log = new_log(sd, peer->log_book, "%s(%s):", name, idstr);
+		tal_free(idstr);
+	} else {
+		sd->log = new_log(sd, ld->log_book, "%s(%u):", name, sd->pid);
+	}
+
 	sd->name = name;
 	sd->must_not_exit = false;
 	sd->msgname = msgname;