Also sync VST3 audio thread scheduling priorities

The exact same thing as the last commit, but for VST3 plugins.

src/common/serialization/vst3/plugin/audio-processor.h

@@ -250,10 +250,22 @@ class YaAudioProcessor : public Steinberg::Vst::IAudioProcessor {
 
         YaProcessData data;
 
+        /**
+         * We'll periodically synchronize the realtime priority setting of the
+         * host's audio thread with the Wine plugin host. We'll do this
+         * approximately every ten seconds, as doing this getting and setting
+         * scheduler information has a non trivial amount of overhead (even if
+         * it's only a single microsoecond).
+         */
+        std::optional<int> new_realtime_priority;
+
         template <typename S>
         void serialize(S& s) {
             s.value8b(instance_id);
             s.object(data);
+
+            s.ext(new_realtime_priority, bitsery::ext::StdOptional{},
+                  [](S& s, int& priority) { s.value4b(priority); });
         }
     };
 

src/common/utils.h

@@ -21,6 +21,14 @@
 #endif
 #include <boost/filesystem.hpp>
 
+/**
+ * The interval in seconds between synchronizing the Wine plugin host's audio
+ * thread scheduling priority with the host's audio thread.
+ *
+ * @relates Vst2Bridge::last_audio_thread_priority_synchronization
+ */
+constexpr time_t audio_thread_priority_synchronization_interval = 10;
+
 // The cannonical overloading template for `std::visitor`, not sure why this
 // isn't part of the standard library
 template <class... Ts>

src/plugin/bridges/vst2.cpp

@@ -19,14 +19,6 @@
 #include "../../common/communication/vst2.h"
 #include "../utils.h"
 
-/**
- * The interval in seconds between synchronizing the Wine plugin host's audio
- * thread scheduling priority with the host's audio thread.
- *
- * @relates Vst2Bridge::last_audio_thread_priority_synchronization
- */
-constexpr time_t audio_thread_priority_synchronization_interval = 10;
-
 intptr_t dispatch_proxy(AEffect*, int, int, intptr_t, void*, float);
 void process_proxy(AEffect*, float**, float**, int);
 void process_replacing_proxy(AEffect*, float**, float**, int);

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

@@ -141,10 +141,23 @@ tresult PLUGIN_API Vst3PluginProxyImpl::setProcessing(TBool state) {
 
 tresult PLUGIN_API
 Vst3PluginProxyImpl::process(Steinberg::Vst::ProcessData& data) {
+    // We'll synchronize the scheduling priority of the audio thread on the Wine
+    // plugin host with that of the host's audio thread every once in a while
+    std::optional<int> new_realtime_priority = std::nullopt;
+    time_t now = std::time(nullptr);
+    if (now > last_audio_thread_priority_synchronization +
+                  audio_thread_priority_synchronization_interval) {
+        new_realtime_priority = get_realtime_priority();
+        last_audio_thread_priority_synchronization = now;
+    }
+
     // TODO: Check whether reusing a `YaProcessData` object make a difference in
     //       terms of performance
-    ProcessResponse response = bridge.send_audio_processor_message(
-        YaAudioProcessor::Process{.instance_id = instance_id(), .data = data});
+    ProcessResponse response =
+        bridge.send_audio_processor_message(YaAudioProcessor::Process{
+            .instance_id = instance_id(),
+            .data = data,
+            .new_realtime_priority = new_realtime_priority});
 
     response.output_data.write_back_outputs(data);
 

src/plugin/bridges/vst3-impls/plugin-proxy.h

@@ -375,6 +375,13 @@ class Vst3PluginProxyImpl : public Vst3PluginProxy {
      */
     Steinberg::IPtr<Steinberg::FUnknown> host_context;
 
+    /**
+     * We'll periodically synchronize the Wine host's audio thread priority with
+     * that of the host. Since the overhead from doing so does add up, we'll
+     * only do this every once in a while.
+     */
+    time_t last_audio_thread_priority_synchronization = 0;
+
     /**
      * Used to assign unique identifiers to context menus created by
      * `IComponentHandler3::CreateContextMenu`.

src/wine-host/bridges/vst3.cpp

@@ -1129,6 +1129,14 @@ size_t Vst3Bridge::register_object_instance(
                     },
                     [&](YaAudioProcessor::Process& request)
                         -> YaAudioProcessor::Process::Response {
+                        // As suggested by Jack Winter, we'll synchronize this
+                        // thread's audio processing priority with that of the
+                        // host's audio thread every once in a while
+                        if (request.new_realtime_priority) {
+                            set_realtime_priority(
+                                true, *request.new_realtime_priority);
+                        }
+
                         const tresult result =
                             object_instances[request.instance_id]
                                 .audio_processor->process(request.data.get());