EXPERIMENTAL: dev-quiesce to initiate (and test) quiescence.

Signed-off-by: Rusty Russell <[email protected]>

channeld/channeld.c

@@ -294,9 +294,11 @@ static void maybe_send_stfu(struct peer *peer)
 		peer->stfu_sent[LOCAL] = true;
 	}
 
-	/* FIXME: We're finished, do something! */
-	if (peer->stfu_sent[LOCAL] && peer->stfu_sent[REMOTE])
+	if (peer->stfu_sent[LOCAL] && peer->stfu_sent[REMOTE]) {
 		status_unusual("STFU complete: we are quiescent");
+		wire_sync_write(MASTER_FD,
+				towire_channeld_dev_quiesce_reply(tmpctx));
+	}
 }
 
 static void handle_stfu(struct peer *peer, const u8 *stfu)
@@ -3057,6 +3059,21 @@ static void channeld_send_custommsg(struct peer *peer, const u8 *msg)
 		master_badmsg(WIRE_CUSTOMMSG_OUT, msg);
 	sync_crypto_write(peer->pps, take(inner));
 }
+
+#if EXPERIMENTAL_FEATURES
+static void handle_dev_quiesce(struct peer *peer, const u8 *msg)
+{
+	if (!fromwire_channeld_dev_quiesce(msg))
+		master_badmsg(WIRE_CHANNELD_DEV_QUIESCE, msg);
+
+	/* Don't do this twice. */
+	if (peer->stfu)
+		status_failed(STATUS_FAIL_MASTER_IO, "dev_quiesce already");
+
+	peer->stfu = true;
+	maybe_send_stfu(peer);
+}
+#endif /* EXPERIMENTAL_FEATURES */
 #endif /* DEVELOPER */
 
 static void req_in(struct peer *peer, const u8 *msg)
@@ -3105,9 +3122,15 @@ static void req_in(struct peer *peer, const u8 *msg)
 	case WIRE_CHANNELD_DEV_MEMLEAK:
 		handle_dev_memleak(peer, msg);
 		return;
+	case WIRE_CHANNELD_DEV_QUIESCE:
+#if EXPERIMENTAL_FEATURES
+		handle_dev_quiesce(peer, msg);
+		return;
+#endif /* EXPERIMENTAL_FEATURES */
 #else
 	case WIRE_CHANNELD_DEV_REENABLE_COMMIT:
 	case WIRE_CHANNELD_DEV_MEMLEAK:
+	case WIRE_CHANNELD_DEV_QUIESCE:
 #endif /* DEVELOPER */
 	case WIRE_CHANNELD_INIT:
 	case WIRE_CHANNELD_OFFER_HTLC_REPLY:
@@ -3125,6 +3148,7 @@ static void req_in(struct peer *peer, const u8 *msg)
 	case WIRE_CHANNELD_FAIL_FALLEN_BEHIND:
 	case WIRE_CHANNELD_DEV_MEMLEAK_REPLY:
 	case WIRE_CHANNELD_SEND_ERROR_REPLY:
+	case WIRE_CHANNELD_DEV_QUIESCE_REPLY:
 		break;
 	}
 

channeld/channeld_wire.csv

@@ -217,3 +217,7 @@ msgdata,channeld_send_error,reason,wirestring,
 
 # Tell master channeld has sent the error message.
 msgtype,channeld_send_error_reply,1108
+
+# Ask channeld to quiesce.
+msgtype,channeld_dev_quiesce,1009
+msgtype,channeld_dev_quiesce_reply,1109

lightningd/channel_control.c

@@ -425,11 +425,13 @@ static unsigned channel_msg(struct subd *sd, const u8 *msg, const int *fds)
 	case WIRE_CHANNELD_FEERATES:
 	case WIRE_CHANNELD_SPECIFIC_FEERATES:
 	case WIRE_CHANNELD_DEV_MEMLEAK:
+	case WIRE_CHANNELD_DEV_QUIESCE:
 		/* Replies go to requests. */
 	case WIRE_CHANNELD_OFFER_HTLC_REPLY:
 	case WIRE_CHANNELD_DEV_REENABLE_COMMIT_REPLY:
 	case WIRE_CHANNELD_DEV_MEMLEAK_REPLY:
 	case WIRE_CHANNELD_SEND_ERROR:
+	case WIRE_CHANNELD_DEV_QUIESCE_REPLY:
 		break;
 	}
 
@@ -937,4 +939,54 @@ static const struct json_command dev_feerate_command = {
 	"Set feerate for {id} to {feerate}"
 };
 AUTODATA(json_command, &dev_feerate_command);
+
+#if EXPERIMENTAL_FEATURES
+static void quiesce_reply(struct subd *channeld UNUSED,
+			  const u8 *reply,
+			  const int *fds UNUSED,
+			  struct command *cmd)
+{
+	struct json_stream *response;
+
+	response = json_stream_success(cmd);
+	was_pending(command_success(cmd, response));
+}
+
+static struct command_result *json_dev_quiesce(struct command *cmd,
+					       const char *buffer,
+					       const jsmntok_t *obj UNNEEDED,
+					       const jsmntok_t *params)
+{
+	struct node_id *id;
+	struct peer *peer;
+	struct channel *channel;
+	const u8 *msg;
+
+	if (!param(cmd, buffer, params,
+		   p_req("id", param_node_id, &id),
+		   NULL))
+		return command_param_failed();
+
+	peer = peer_by_id(cmd->ld, id);
+	if (!peer)
+		return command_fail(cmd, LIGHTNINGD, "Peer not connected");
+
+	channel = peer_active_channel(peer);
+	if (!channel || !channel->owner || channel->state != CHANNELD_NORMAL)
+		return command_fail(cmd, LIGHTNINGD, "Peer bad state");
+
+	msg = towire_channeld_dev_quiesce(NULL);
+	subd_req(channel->owner, channel->owner, take(msg), -1, 0,
+		 quiesce_reply, cmd);
+	return command_still_pending(cmd);
+}
+
+static const struct json_command dev_quiesce_command = {
+	"dev-quiesce",
+	"developer",
+	json_dev_quiesce,
+	"Initiate quiscence protocol with peer"
+};
+AUTODATA(json_command, &dev_quiesce_command);
+#endif /* EXPERIMENTAL_FEATURES */
 #endif /* DEVELOPER */

tests/test_connection.py

@@ -3494,3 +3494,27 @@ def test_htlc_failed_noclose(node_factory):
 
     time.sleep(35)
     assert l1.rpc.getpeer(l2.info['id'])['connected']
+
+
+@unittest.skipIf(not EXPERIMENTAL_FEATURES, "quiescence is experimental")
+@pytest.mark.developer("quiescence triggering is dev only")
+def test_quiescence(node_factory, executor):
+    l1, l2 = node_factory.line_graph(2)
+
+    # Works fine.
+    l1.pay(l2, 1000)
+
+    assert l1.rpc.call('dev-quiesce', [l2.info['id']]) == {}
+
+    # Both should consider themselves quiescent.
+    l1.daemon.wait_for_log("STFU complete: we are quiescent")
+    l2.daemon.wait_for_log("STFU complete: we are quiescent")
+
+    # Should not be able to increase fees.
+    l1.rpc.call('dev-feerate', [l2.info['id'], 9999])
+
+    try:
+        l1.daemon.wait_for_log('peer_out WIRE_UPDATE_FEE', 5)
+        assert False
+    except TimeoutError:
+        pass