Move the flush request to the audio thread

src/common/serialization/clap.h

@@ -151,11 +151,7 @@ using ClapMainThreadCallbackRequest =
                  clap::ext::note_ports::host::SupportedDialects,
                  clap::ext::note_ports::host::Rescan,
                  clap::ext::params::host::Rescan,
-                 clap::ext::params::host::Clear,
-                 // This doesn't need to be done on the main thread, but we
-                 // don't have an alternative per-plugin instance socket
-                 // available so this is probably fine
-                 clap::ext::params::host::RequestFlush>;
+                 clap::ext::params::host::Clear>;
 
 template <typename S>
 void serialize(S& s, ClapMainThreadCallbackRequest& payload) {
@@ -177,7 +173,9 @@ void serialize(S& s, ClapMainThreadCallbackRequest& payload) {
  *       used.
  */
 using ClapAudioThreadCallbackRequest =
-    std::variant<WantsConfiguration, clap::ext::tail::host::Changed>;
+    std::variant<WantsConfiguration,
+                 clap::ext::params::host::RequestFlush,
+                 clap::ext::tail::host::Changed>;
 
 template <typename S>
 void serialize(S& s, ClapAudioThreadCallbackRequest& payload) {

src/common/serialization/clap/ext/params.h

@@ -223,8 +223,6 @@ struct FlushResponse {
     }
 };
 
-// TODO: This can be either a main thread or an audio thread function call
-//       depending on whether or not the plugin is active
 /**
  * Message struct for `clap_plugin_params::flush()`.
  */

src/plugin/bridges/clap.cpp

@@ -179,17 +179,6 @@ ClapPluginBridge::ClapPluginBridge(const ghc::filesystem::path& plugin_path)
 
                     return Ack{};
                 },
-                [&](const clap::ext::params::host::RequestFlush& request)
-                    -> clap::ext::params::host::RequestFlush::Response {
-                    const auto& [plugin_proxy, _] =
-                        get_proxy(request.owner_instance_id);
-
-                    // This doesn't need to be called from the main thread
-                    plugin_proxy.host_extensions_.params->request_flush(
-                        plugin_proxy.host_);
-
-                    return Ack{};
-                },
             });
     });
 }
@@ -277,6 +266,16 @@ void ClapPluginBridge::register_plugin_proxy(
                     //        hell. I haven't been able to figure out why.
                     return {};
                 },
+                [&](const clap::ext::params::host::RequestFlush& request)
+                    -> clap::ext::params::host::RequestFlush::Response {
+                    const auto& [plugin_proxy, _] =
+                        get_proxy(request.owner_instance_id);
+
+                    plugin_proxy.host_extensions_.params->request_flush(
+                        plugin_proxy.host_);
+
+                    return Ack{};
+                },
                 [&](const clap::ext::tail::host::Changed& request)
                     -> clap::ext::tail::host::Changed::Response {
                     // FIXME:

src/plugin/bridges/clap.h

@@ -116,8 +116,8 @@ class ClapPluginBridge : PluginBridge<ClapSockets<std::jthread>> {
     }
 
     /**
-     * Send an a message to a plugin instance's audio thread. This is separate
-     * from `send_message()`, which shares one socket for all plugin instances.
+     * Send a message to a plugin instance's audio thread. This is separate from
+     * `send_message()`, which shares one socket for all plugin instances.
      */
     template <typename T>
     typename T::Response send_audio_thread_message(const T& object) {

src/wine-host/bridges/clap-impls/host-proxy.cpp

@@ -197,7 +197,7 @@ clap_host_proxy::ext_params_request_flush(const clap_host_t* host) {
     assert(host && host->host_data);
     auto self = static_cast<clap_host_proxy*>(host->host_data);
 
-    self->bridge_.send_main_thread_message(
+    self->bridge_.send_audio_thread_message(
         clap::ext::params::host::RequestFlush{.owner_instance_id =
                                                   self->owner_instance_id()});
 }