Request/send config for VST3 plugins

Using the new Vst3MessageHandler.

src/common/communication/common.h

@@ -195,7 +195,11 @@ class Sockets {
     /**
      * Depending on the value of the `listen` argument passed to the
      * constructor, either accept connections made to the sockets on the Linux
-     * side or connect to the sockets on the Wine side
+     * side or connect to the sockets on the Wine side.
+     *
+     * @remark On the plugin side `PluginBridge::connect_sockets_guarded()`
+     *   should be used instead so we can terminate everything in the event that
+     *   Wine fails to start.
      */
     virtual void connect() = 0;
 

src/plugin/bridges/vst3.cpp

@@ -38,8 +38,20 @@ Vst3PluginBridge::Vst3PluginBridge()
     // host
     connect_sockets_guarded();
 
+    // Now that communication is set up the Wine host can send callbacks to this
+    // bridge class, and we can send control messages to the Wine host. This
+    // messaging mechanism is how we relay the VST3 communication protocol. As a
+    // first thing, the Wine VST host will ask us for a copy of the
+    // configuration.
     host_callback_handler = std::jthread([&]() {
-        // TODO: Handle callbacks
-        // sockets.vst_host_callback.receive_multi();
+        sockets.vst_host_callback.receive_messages(
+            std::pair<Vst3Logger&, bool>(logger, false),
+            [&](CallbackRequest request) -> CallbackResponse {
+                return std::visit(overload{[&](const WantsConfiguration&)
+                                               -> WantsConfiguration::Response {
+                                      return config;
+                                  }},
+                                  request);
+            });
     });
 }

src/wine-host/bridges/common.h

@@ -78,7 +78,10 @@ class HostBridge {
      * Wine window, and embedding that Wine window into a window provided by the
      * host. Should be empty when the editor is not open.
      *
-     * @see should_postpone_message_loop
+     * TODO: This should be moved back to `Vst2Bridge`, `handle_x11_events()``
+     *       and `handle_win32_events()` should be made pure virtual. A single
+     *       `Vst3Bridge` instance will handle multiple plugin instances because
+     *       of the way VST3 works.
      */
     std::optional<Editor> editor;
 };

src/wine-host/bridges/vst2.h

@@ -63,6 +63,10 @@ class Vst2Bridge : public HostBridge {
                std::string plugin_dll_path,
                std::string endpoint_base_dir);
 
+    /**
+     * Here we'll handle incoming `dispatch()` messages until the sockets get
+     * closed during `effClose()`.
+     */
     void run() override;
 
     /**

src/wine-host/bridges/vst3.cpp

@@ -45,16 +45,17 @@ Vst3Bridge::Vst3Bridge(MainContext& main_context,
 
     sockets.connect();
 
-    // TODO: We should send a copy of the configuration from the plugin at this
-    // point config = sockets.host_vst_control.receive_single<Configuration>();
-
-    control_handler = Win32Thread([&]() {
-        // TODO: Handle control messages
-        // sockets.host_vst_control.receive_multi();
-    });
+    // Fetch this instance's configuration from the plugin to finish the setup
+    // process
+    config = sockets.vst_host_callback.send_message(WantsConfiguration{},
+                                                    std::nullopt);
 }
 
 void Vst3Bridge::run() {
-    // TODO: Do something
+    // TODO: Handle events
+    // sockets.host_vst_control.receive_messages(
+    //     std::nullopt, [&](ControlRequest request) -> ControlResponse {
+    //     });
+
     std::cerr << "TODO: Not yet implemented" << std::endl;
 }

src/wine-host/bridges/vst3.h

@@ -52,6 +52,10 @@ class Vst3Bridge : public HostBridge {
                std::string plugin_dll_path,
                std::string endpoint_base_dir);
 
+    /**
+     * Here we'll listen for and handle incoming control messages until the
+     * sockets get closed.
+     */
     void run() override;
 
    private:
@@ -79,9 +83,4 @@ class Vst3Bridge : public HostBridge {
      *       threads to exit.
      */
     Vst3Sockets<Win32Thread> sockets;
-
-    /**
-     * Handles control messages host over the `hsot_vst_control` sockets.
-     */
-    Win32Thread control_handler;
 };