Keep track of active YaComponentPluginImpls

So we can do host callbacks later.

src/plugin/bridges/vst3-impls/component.cpp

@@ -18,11 +18,14 @@
 
 YaComponentPluginImpl::YaComponentPluginImpl(Vst3PluginBridge& bridge,
                                              YaComponent::ConstructArgs&& args)
-    : YaComponent(std::move(args)), bridge(bridge) {}
+    : YaComponent(std::move(args)), bridge(bridge) {
+    bridge.register_component(arguments.instance_id, *this);
+}
 
 YaComponentPluginImpl::~YaComponentPluginImpl() {
     bridge.send_message(
         YaComponent::Destruct{.instance_id = arguments.instance_id});
+    bridge.unregister_component(arguments.instance_id);
 }
 
 tresult PLUGIN_API

src/plugin/bridges/vst3.cpp

@@ -105,3 +105,15 @@ Steinberg::IPluginFactory* Vst3PluginBridge::get_plugin_factory() {
 
     return plugin_factory;
 }
+
+void Vst3PluginBridge::register_component(size_t instance_id,
+                                          YaComponentPluginImpl& component) {
+    std::lock_guard lock(component_instances_mutex);
+    component_instances.emplace(instance_id,
+                                std::ref<YaComponentPluginImpl>(component));
+}
+
+void Vst3PluginBridge::unregister_component(size_t instance_id) {
+    std::lock_guard lock(component_instances_mutex);
+    component_instances.erase(instance_id);
+}

src/plugin/bridges/vst3.h

@@ -23,6 +23,9 @@
 #include "../../common/logging/vst3.h"
 #include "common.h"
 
+// Forward declaration
+class YaComponentPluginImpl;
+
 /**
  * This handles the communication between the native host and a VST3 plugin
  * hosted in our Wine plugin host. VST3 is handled very differently from VST2
@@ -63,6 +66,35 @@ class Vst3PluginBridge : PluginBridge<Vst3Sockets<std::jthread>> {
      */
     Steinberg::IPluginFactory* get_plugin_factory();
 
+    /**
+     * Add a `YaComponentPluginImpl` to the list of registered components so we
+     * can handle host callbacks, called during its constructor.
+     *
+     * @param instance_id The instance ID generated by the plugin host when
+     *   instantiating the `IComponent`. Used as a stable name to refer to
+     *   these.
+     * @param component The actual component instance so we can use its host
+     *   context.
+     *
+     * @see component_instances
+     */
+    void register_component(size_t instance_id,
+                            YaComponentPluginImpl& component);
+
+    /**
+     * Remove a previously registered `YaComponentPluginImpl` from the list of
+     * registered components so we can handle host callbacks, called during its
+     * destructor after asking the Wine plugin host to destroy the component on
+     * its side..
+     *
+     * @param instance_id The instance ID generated by the plugin host when
+     *   instantiating the `IComponent`. Used as a stable name to refer to
+     *   these.
+     *
+     * @see component_instances
+     */
+    void unregister_component(size_t instance_id);
+
     /**
      * Send a control message to the Wine plugin host return the response. This
      * is a shorthand for `sockets.host_vst_control.send_message` for use in
@@ -98,4 +130,20 @@ class Vst3PluginBridge : PluginBridge<Vst3Sockets<std::jthread>> {
      * @related get_plugin_factory
      */
     YaPluginFactory* plugin_factory;
+
+   private:
+    /**
+     * All `IComponent` instances we created from this plugin. We only need to
+     * keep track of them in case the 'real' `IComponent` instance tries to do a
+     * callback through the host context. We store the copy of the host context
+     * passed during `initialize()` in the `YaComponentPluginImpl`. The IDs here
+     * are the same IDs as generated by the Wine plugin host. We store raw
+     * pointers instead of smart pointers because this shouldn't affect the
+     * reference counting. An instance is added here through a call by
+     * `register_component()` in the constractor, and an instance is then
+     * removed through a call to `unregister_component()` in the destructor.
+     */
+    std::map<size_t, std::reference_wrapper<YaComponentPluginImpl>>
+        component_instances;
+    std::mutex component_instances_mutex;
 };