Simplify connection process This patch refactors and simplifies connection process, which has been messy as it was designed for C API. This refactor also removed the unnecessary short-lived WebSocket connection on startup. That unorganized `try_listen` / `start` methods have been pain point for me. It was unclear how the class calls methods one by another, by looking at class. Elimination of startup short-lived WebSocket connection reduces startup time. It was not a bothering one, but there is no technical reason to close the established connection so this is good.

Changes

5 changed files (+290/-330)

• src/Application.vala
  • @@ -46,14 +46,7 @@ var selector = new ServerSelector.Window(this);
    selector.start(); } else { var main_window = new MainWindow.from_server_id(this, settings.connected_server_id); - if (settings.connected_server_addr != "" && settings.connected_server_port > 0) { - main_window.start_with_addr( - settings.connected_server_addr, - settings.connected_server_port - ); - } else { - main_window.start(); - } + main_window.start(); } }
• src/Plac/Connection.vala
  • @@ -15,6 +15,13 @@ //
    // SPDX-License-Identifier: Apache-2.0 namespace Plac { + public errordomain ConnectError { + SERVER_NOT_FOUND, + INVALID_RESPONSE, + SERVER_MISMATCH, + NETWORK_ERROR, + } + public errordomain RequestError { NETWORK_ERROR, UNEXPECTED_RESPONSE,
  • @@ -47,6 +54,129 @@
    conn.send_binary(@"$res_meta$res_headers".data); } + private static async Response send_request( + Soup.WebsocketConnection conn, + string service, + uint64 request_id, + string? json_body = null + ) throws RequestError { + SourceFunc callback = send_request.callback; + Response? resp = null; + + var message_handler_id = conn.message.connect((c, type, bytes) => { + var message = (string) bytes.get_data(); + + Moo.Metadata res_meta; + Moo.Headers res_headers; + try { + res_meta = new Moo.Metadata.from_string(message); + res_headers = new Moo.Headers.from_string(message, res_meta); + } catch (GLib.Error error) { + GLib.log("Plac", LEVEL_WARNING, "Got invalid MOO message: %s", error.message); + return; + } + + if (res_meta.verb == "REQUEST") { + // Application ping message, skip. + return; + } + + if (res_headers.request_id != request_id) { + return; + } + + resp = new Response(res_meta, res_headers, message); + callback(); + }); + + var error_handler_id = conn.error.connect((c, error) => { + GLib.log("Plac", LEVEL_ERROR, "Failed to receive MOO message: %s", error.message); + callback(); + }); + + var req_meta = new Moo.Metadata("REQUEST", service); + var req_headers = new Moo.Headers(); + req_headers.write("Request-Id", @"$request_id"); + + if (json_body != null) { + req_headers.write("Content-Type", "application/json"); + req_headers.write("Content-Length", @"$(json_body.length)"); + + conn.send_binary(@"$req_meta$req_headers$json_body".data); + } else { + conn.send_binary(@"$req_meta$req_headers".data); + } + + yield; + + conn.disconnect(message_handler_id); + conn.disconnect(error_handler_id); + + if (resp == null) { + throw new RequestError.NETWORK_ERROR("Server not found."); + } + + return resp; + } + + private static async Roon.Registry.Info.Response get_registry_info( + Soup.WebsocketConnection conn, uint64 request_id = 1 + ) throws ConnectError { + Response resp; + try { + resp = yield send_request(conn, "com.roonlabs.registry:1/info", request_id); + } catch (RequestError error) { + if (error is RequestError.NETWORK_ERROR) { + throw new ConnectError.NETWORK_ERROR(error.message); + } + + throw new ConnectError.INVALID_RESPONSE(error.message); + } + + if (resp.meta.service != "Success") { + throw new ConnectError.INVALID_RESPONSE("Server error."); + } + + if (resp.headers.content_type != "application/json") { + throw new ConnectError.INVALID_RESPONSE("Not a JSON body."); + } + + Roon.Registry.Info.Response info; + try { + var body = new Moo.JsonBody.from_string(resp.message, resp.headers); + + info = new Roon.Registry.Info.Response.from_json(body.data); + } catch (GLib.Error error) { + throw new ConnectError.INVALID_RESPONSE(error.message); + } + + return info; + } + + private static async Soup.WebsocketConnection ws_connect_async( + GLib.InetSocketAddress address, + uint16 port, + GLib.Cancellable? cancellable = null + ) throws GLib.Error { + var session_singleton = new Session(); + var session = session_singleton.session; + + var url = GLib.Uri.build( + NONE, "ws:", null, address.address.to_string(), port, + "/api", null, null + ); + var msg = new Soup.Message.from_uri("GET", url); + + // Roon API does not specify WebSocket subprotocols. + Soup.WebsocketConnection conn = yield session.websocket_connect_async( + msg, null, null, GLib.Priority.DEFAULT, cancellable + ); + + conn.message.connect(handle_ping); + + return conn; + } + // TODO: Handle connection close and reconnect public class Connection : Object { private size_t request_id = 1;
  • @@ -59,64 +189,67 @@ public Connection(Soup.WebsocketConnection conn, Server server, string token) {
    Object(conn: conn, server: server, token: token); } - public async Response json_request(string service, string body) throws RequestError { - SourceFunc callback = json_request.callback; - - var req_id = request_id; - request_id += 1; + public static async Connection connect_async( + GLib.InetSocketAddress address, uint16 http_port, string server_id, + Roon.Registry.Register.Request req, + GLib.Cancellable? cancellable = null + ) throws ConnectError { + Soup.WebsocketConnection conn; + try { + conn = yield ws_connect_async(address, http_port, cancellable); + } catch (GLib.Error error) { + GLib.log("Plac", LEVEL_DEBUG, "Handshake error"); + throw new ConnectError.NETWORK_ERROR(error.message); + } - Response? resp = null; - GLib.Error? error = null; + Roon.Registry.Info.Response info; + try { + info = yield get_registry_info(conn); + } catch (ConnectError error) { + throw new ConnectError.SERVER_NOT_FOUND(error.message); + } - var message_handler_id = conn.message.connect((c, type, bytes) => { - var message = (string) bytes.get_data(); + if (info.core_id != server_id) { + throw new ConnectError.SERVER_MISMATCH("Server at the location has different server ID."); + } - Moo.Metadata res_meta; - Moo.Headers res_headers; - try { - res_meta = new Moo.Metadata.from_string(message); - res_headers = new Moo.Headers.from_string(message, res_meta); - } catch (GLib.Error error) { - GLib.log("Plac", LEVEL_WARNING, "Got invalid MOO message: %s", error.message); - return; - } + GLib.log("Plac", LEVEL_DEBUG, "Confirmed the Roon server is running. Registering extension."); - if (res_meta.verb == "REQUEST" || res_headers.request_id != req_id) { - return; + Response register_resp; + try { + register_resp = yield send_request(conn, "com.roonlabs.registry:1/register", 2, req.to_json()); + } catch (RequestError error) { + if (error is RequestError.NETWORK_ERROR) { + throw new ConnectError.NETWORK_ERROR(error.message); } - resp = new Response(res_meta, res_headers, message); - callback(); - }); - - var error_handler_id = conn.error.connect((c, error) => { - GLib.log("Plac", LEVEL_ERROR, "Failed to receive MOO message: %s", error.message); - callback(); - }); - - var req_meta = new Moo.Metadata("REQUEST", service); - var req_headers = new Moo.Headers(); - req_headers.write("Request-Id", @"$req_id"); - - req_headers.write("Content-Type", "application/json"); - req_headers.write("Content-Length", @"$(body.length)"); - - conn.send_binary(@"$req_meta$req_headers$body".data); + throw new ConnectError.INVALID_RESPONSE(error.message); + } - yield; + if (register_resp.meta.service != "Registered") { + throw new ConnectError.INVALID_RESPONSE(@"$(register_resp.meta.service)"); + } - conn.disconnect(message_handler_id); - conn.disconnect(error_handler_id); + Roon.Registry.Register.Response result; + try { + var body = new Moo.JsonBody.from_string(register_resp.message, register_resp.headers); - if (error != null) { - throw new RequestError.NETWORK_ERROR(error.message); + result = new Roon.Registry.Register.Response.from_json(body.data); + } catch (GLib.Error error) { + throw new ConnectError.INVALID_RESPONSE(error.message); } - if (resp == null) { - throw new RequestError.UNEXPECTED_RESPONSE("Got unexpected response from Roon server, failed to parse."); - } + GLib.log("Plac", LEVEL_DEBUG, @"Registered Roon extension at $(address.address):$(http_port)"); - return resp; + return new Connection( + conn, + new Server(address, server_id, info.display_version, info.display_name, http_port), + result.token + ); + } + + public async Response json_request(string service, string body) throws RequestError { + return yield send_request(conn, service, request_id ++, body); } } }
• src/Plac/Server.vala
  • @@ -21,15 +21,7 @@ SERVER_MISMATCH,
    NETWORK_ERROR, } - public errordomain ConnectError { - SERVER_NOT_FOUND, - INVALID_REQUEST, - INVALID_RESPONSE, - SERVER_MISMATCH, - NETWORK_ERROR, - } - - public class Server : Object { + public class Server : Object, WebSocketConnectable { /** * IP address of the server. */
  • @@ -54,187 +46,6 @@ public string name { get; construct; }
    public Server(GLib.InetSocketAddress address, string id, string version, string name, uint16 http_port) { Object(address: address, id: id, version: version, name: name, http_port: http_port); - } - - public static async Server from_address( - GLib.InetSocketAddress address, uint16 http_port, string id, GLib.Cancellable? cancellable = null - ) throws ResolveServerError { - Soup.WebsocketConnection conn; - try { - conn = yield ws_connect(address, http_port, cancellable); - } catch (GLib.Error error) { - GLib.log("Plac", LEVEL_DEBUG, "Handshake error"); - throw new ResolveServerError.NETWORK_ERROR(error.message); - } - - Roon.Registry.Info.Response info; - try { - info = yield get_registry_info(conn); - } catch (ConnectError error) { - throw new ResolveServerError.SERVER_NOT_FOUND(error.message); - } - - if (info.core_id != id) { - throw new ResolveServerError.SERVER_MISMATCH("Server at the location has different server ID."); - } - - return new Server(address, id, info.display_version, info.display_name, http_port); - } - - /** - * TODO: Move connection-related code to `Connection` class - */ - private static async Soup.WebsocketConnection ws_connect( - GLib.InetSocketAddress address, - uint16 port, - GLib.Cancellable? cancellable = null - ) throws GLib.Error { - var session_singleton = new Session(); - var session = session_singleton.session; - - var url = GLib.Uri.build( - NONE, "ws:", null, address.address.to_string(), port, - "/api", null, null - ); - var msg = new Soup.Message.from_uri("GET", url); - - // Roon API does not specify WebSocket subprotocols. - Soup.WebsocketConnection conn = yield session.websocket_connect_async( - msg, null, null, GLib.Priority.DEFAULT, cancellable - ); - - conn.message.connect(handle_ping); - - return conn; - } - - private static async Response send_request( - Soup.WebsocketConnection conn, - string service, - uint64 request_id, - string? json_body = null - ) throws ConnectError { - SourceFunc callback = send_request.callback; - Response? resp = null; - - var message_handler_id = conn.message.connect((c, type, bytes) => { - var message = (string) bytes.get_data(); - - Moo.Metadata res_meta; - Moo.Headers res_headers; - try { - res_meta = new Moo.Metadata.from_string(message); - res_headers = new Moo.Headers.from_string(message, res_meta); - } catch (GLib.Error error) { - GLib.log("Plac", LEVEL_WARNING, "Got invalid MOO message: %s", error.message); - return; - } - - if (res_meta.verb == "REQUEST") { - // Application ping message, skip. - return; - } - - if (res_headers.request_id != request_id) { - GLib.log("Plac", LEVEL_DEBUG, "Ignoring response with unexpected Request-Id"); - return; - } - - resp = new Response(res_meta, res_headers, message); - callback(); - }); - - var error_handler_id = conn.error.connect((c, error) => { - GLib.log("Plac", LEVEL_ERROR, "Failed to receive MOO message: %s", error.message); - callback(); - }); - - var req_meta = new Moo.Metadata("REQUEST", service); - var req_headers = new Moo.Headers(); - req_headers.write("Request-Id", @"$request_id"); - - if (json_body != null) { - req_headers.write("Content-Type", "application/json"); - req_headers.write("Content-Length", @"$(json_body.length)"); - - conn.send_binary(@"$req_meta$req_headers$json_body".data); - } else { - conn.send_binary(@"$req_meta$req_headers".data); - } - - yield; - - conn.disconnect(message_handler_id); - conn.disconnect(error_handler_id); - - if (resp == null) { - throw new ConnectError.SERVER_NOT_FOUND("Server not found."); - } - - return resp; - } - - private static async Roon.Registry.Info.Response get_registry_info( - Soup.WebsocketConnection conn, uint64 request_id = 1 - ) throws ConnectError { - var resp = yield send_request(conn, "com.roonlabs.registry:1/info", request_id); - - if (resp.meta.service != "Success") { - throw new ConnectError.INVALID_RESPONSE("Server error."); - } - - if (resp.headers.content_type != "application/json") { - throw new ConnectError.INVALID_RESPONSE("Not a JSON body."); - } - - Roon.Registry.Info.Response info; - try { - var body = new Moo.JsonBody.from_string(resp.message, resp.headers); - - info = new Roon.Registry.Info.Response.from_json(body.data); - } catch (GLib.Error error) { - throw new ConnectError.INVALID_RESPONSE(error.message); - } - - return info; - } - - public async Connection connect_async(Roon.Registry.Register.Request req) throws ConnectError { - GLib.log("Plac", LEVEL_DEBUG, @"Connecting to $(this.address.address):$(this.http_port)"); - - Soup.WebsocketConnection conn; - try { - conn = yield ws_connect(address, http_port); - } catch (GLib.Error error) { - GLib.log("Plac", LEVEL_DEBUG, "Handshake error"); - throw new ConnectError.NETWORK_ERROR(error.message); - } - - var info = yield get_registry_info(conn, 1); - - if (info.core_id != id) { - throw new ConnectError.SERVER_MISMATCH("Got unexpected server ID."); - } - - GLib.log("Plac", LEVEL_DEBUG, "Confirmed the Roon server is running. Registering extension."); - - var register_resp = yield send_request(conn, "com.roonlabs.registry:1/register", 2, req.to_json()); - if (register_resp.meta.service != "Registered") { - throw new ConnectError.INVALID_RESPONSE(@"$(register_resp.meta.service)"); - } - - Roon.Registry.Register.Response result; - try { - var body = new Moo.JsonBody.from_string(register_resp.message, register_resp.headers); - - result = new Roon.Registry.Register.Response.from_json(body.data); - } catch (GLib.Error error) { - throw new ConnectError.INVALID_RESPONSE(error.message); - } - - GLib.log("Plac", LEVEL_DEBUG, @"Registered Roon extension at $(this.address.address):$(this.http_port)"); - - return new Connection(conn, this, result.token); } } }
• src/Plac/WebSocketConnectable.vala (new)
  • @@ -0,0 +1,22 @@
    + // Copyright 2025 Shota FUJI + // + // Licensed under the Apache License, Version 2.0 (the "License"); + // you may not use this file except in compliance with the License. + // You may obtain a copy of the License at + // + // http://www.apache.org/licenses/LICENSE-2.0 + // + // Unless required by applicable law or agreed to in writing, software + // distributed under the License is distributed on an "AS IS" BASIS, + // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + // See the License for the specific language governing permissions and + // limitations under the License. + // + // SPDX-License-Identifier: Apache-2.0 + + namespace Plac { + public interface WebSocketConnectable : Object { + public abstract GLib.InetSocketAddress address { get; construct; } + public abstract uint16 http_port { get; construct; } + } + }
• src/Windows/MainWindow.vala
  • @@ -20,6 +20,15 @@ CONNECTION_ERROR,
    SERVER_NOT_FOUND } + private class ServerLocation : Object, Plac.WebSocketConnectable { + public GLib.InetSocketAddress address { get; construct; } + public uint16 http_port { get; construct; } + + public ServerLocation(GLib.InetSocketAddress address, uint16 http_port) { + Object(address: address, http_port: http_port); + } + } + [GtkTemplate(ui = "/jp/pocka/plac/gtk-adwaita/ui/main-window.ui")] class MainWindow : Adw.ApplicationWindow { [GtkChild]
  • @@ -72,7 +81,9 @@ this.display, provider, Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION
    ); error_banner.button_clicked.connect(() => { - try_listen(); + connect_async.begin((_obj, res) => { + connect_async.end(res); + }); }); var explore_row = new BrowseHierarchyRow(BROWSE, "Explore");
  • @@ -106,64 +117,75 @@ }
    public void start() { root_stack.visible_child_name = "loading"; + this.present(); - try_listen(); + connect_async.begin((_obj, res) => { + connect_async.end(res); + }); + } - this.present(); + private async void connect_async() { + Plac.WebSocketConnectable dest; + if (server != null) { + dest = server; + } else if (settings.connected_server_addr != "" && settings.connected_server_port > 0) { + var ip_addr = settings.connected_server_addr; + var port = settings.connected_server_port; + + var colon = ip_addr.index_of(":"); + var patched_ip_addr = colon < 0 ? ip_addr : ip_addr.slice(0, colon); + var address = new GLib.InetSocketAddress.from_string(patched_ip_addr, port); + dest = new ServerLocation(address, port); + } else { + try { + dest = yield resolve_server_async(); + } catch (ResolveError error) { + error_banner.title = error.message; + error_banner.revealed = true; + return; + } + } + + listen_async.begin(dest, (_obj, res) => { + listen_async.end(res); + }); } - public void start_with_addr(string ip_addr, uint16 port) { - root_stack.visible_child_name = "loading"; + private async Plac.Server resolve_server_async() throws ResolveError { + GLib.SourceFunc callback = resolve_server_async.callback; + Plac.Server? server = null; + GLib.Error? error = null; - try_listen_with_addr(ip_addr, port); + var scanner = new Plac.ServerScanner(); + scanner.start(); - this.present(); - } + scanner.found.connect((found) => { + if (server_id == found.id) { + server = found; + callback(); + } + }); - private void try_listen(string? token = null) { - error_banner.revealed = false; + scanner.scan_failed.connect((e) => { + error = e; + }); - if (conn != null) { - listen_events(); - } else { - resolve_server.begin((obj, res) => { - try { - resolve_server.end(res); - } catch (GLib.Error e) { - error_banner.title = e.message; - error_banner.revealed = true; - return; - } + yield; + scanner.stop(); - listen_events(token); - }); + if (error != null) { + throw new ResolveError.CONNECTION_ERROR(error.message); } - } - private void try_listen_with_addr(string ip_addr, uint16 port) { - if (conn != null) { - return; + if (server == null) { + throw new ResolveError.SERVER_NOT_FOUND(error.message); } - var colon = ip_addr.index_of(":"); - var patched_ip_addr = colon < 0 ? ip_addr : ip_addr.slice(0, colon); - var address = new GLib.InetSocketAddress.from_string(patched_ip_addr, port); - Plac.Server.from_address.begin(address, port, server_id, null, (obj, res) => { - try { - this.server = Plac.Server.from_address.end(res); - } catch (Plac.ResolveServerError error) { - GLib.log("Plac", LEVEL_DEBUG, "Failed to resolve: %s", error.message); - GLib.log("Plac", LEVEL_INFO, "Failed to restore connection, scanning server"); - try_listen(settings.connected_server_token); - return; - } - - listen_events(settings.connected_server_token); - }); + return server; } - private void listen_events(string? token = null) { - this.title = "Plac - %s".printf(server.name); + private async void listen_async(Plac.WebSocketConnectable dest) { + var token = settings.connected_server_token; root_stack.visible_child_name = "loading"; playback_toolbar.visible = false;
  • @@ -181,54 +203,33 @@ req.required_services.append_val("com.roonlabs.transport:2");
    req.required_services.append_val("com.roonlabs.browse:1"); req.provided_services.append_val("com.roonlabs.ping:1"); - server.connect_async.begin(req, (obj, res) => { - try { - var conn = server.connect_async.end(res); - this.conn = conn; - zones = new Plac.ZonesModel(conn); - - root_stack.visible_child_name = "main"; - playback_toolbar.visible = true; - - settings.connected_server_id = server.id; - settings.connected_server_token = conn.token; - settings.connected_server_addr = server.address.address.to_string(); - settings.connected_server_port = server.http_port; - - playback_toolbar.conn = conn; - playback_toolbar.zones_model = zones; - browse.start(conn, zones); - } catch (Plac.ConnectError error) { - GLib.log("Plac", LEVEL_CRITICAL, "Failed to connect: %s", error.message); - error_banner.title = "Connection error: %s".printf(error.message); - error_banner.revealed = true; - } - }); - } + try { + var conn = yield Plac.Connection.connect_async( + dest.address, dest.http_port, server_id, req + ); - private async void resolve_server() throws GLib.Error { - GLib.SourceFunc callback = resolve_server.callback; - GLib.Error? error = null; + this.conn = conn; + this.server = conn.server; - var scanner = new Plac.ServerScanner(); - scanner.start(); + this.title = "Plac - %s".printf(server.name); - scanner.found.connect((found) => { - if (server_id == found.id) { - server = found; - callback(); - } - }); + zones = new Plac.ZonesModel(conn); - scanner.scan_failed.connect((e) => { - error = e; - }); + root_stack.visible_child_name = "main"; + playback_toolbar.visible = true; - yield; - scanner.stop(); + settings.connected_server_id = server.id; + settings.connected_server_token = conn.token; + settings.connected_server_addr = server.address.address.to_string(); + settings.connected_server_port = server.http_port; - if (error != null) { - throw error; + playback_toolbar.conn = conn; + playback_toolbar.zones_model = zones; + browse.start(conn, zones); + } catch (Plac.ConnectError error) { + GLib.log("Plac", LEVEL_CRITICAL, "Failed to connect: %s", error.message); + error_banner.title = "Connection error: %s".printf(error.message); + error_banner.revealed = true; } } }