From e0a7fb1dbc7d4d07dce947a43686901dcfa1798a Mon Sep 17 00:00:00 2001
From: Jean Pierre Cimalando <jp-dev@inbox.ru>
Date: Mon, 1 Feb 2021 22:51:24 +0100
Subject: [PATCH] Thread-safety at VST level

---
 vst/CMakeLists.txt        |  3 ++-
 vst/SfizzVstProcessor.cpp | 15 ++++++++++-----
 vst/SfizzVstProcessor.h   |  4 ++--
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/vst/CMakeLists.txt b/vst/CMakeLists.txt
index 02afabef..a2c07724 100644
--- a/vst/CMakeLists.txt
+++ b/vst/CMakeLists.txt
@@ -58,8 +58,9 @@ if(WIN32)
     target_sources(${VSTPLUGIN_PRJ_NAME} PRIVATE vst3.def)
 endif()
 target_link_libraries(${VSTPLUGIN_PRJ_NAME}
-    PRIVATE ${PROJECT_NAME}::${PROJECT_NAME}
+    PRIVATE sfizz::sfizz
     PRIVATE sfizz::editor
+    PRIVATE sfizz::spin_mutex
     PRIVATE sfizz::pugixml sfizz::filesystem)
 target_include_directories(${VSTPLUGIN_PRJ_NAME}
     PRIVATE "${CMAKE_CURRENT_BINARY_DIR}")
diff --git a/vst/SfizzVstProcessor.cpp b/vst/SfizzVstProcessor.cpp
index c77365da..6a22e52f 100644
--- a/vst/SfizzVstProcessor.cpp
+++ b/vst/SfizzVstProcessor.cpp
@@ -138,7 +138,7 @@ tresult PLUGIN_API SfizzVstProcessor::setState(IBStream* stream)
     }
 
     //
-    std::lock_guard<std::mutex> lock(_processMutex);
+    std::lock_guard<SpinMutex> lock(_processMutex);
     _state = s;
 
     syncStateToSynth();
@@ -148,7 +148,7 @@ tresult PLUGIN_API SfizzVstProcessor::setState(IBStream* stream)
 
 tresult PLUGIN_API SfizzVstProcessor::getState(IBStream* stream)
 {
-    std::lock_guard<std::mutex> lock(_processMutex);
+    std::lock_guard<SpinMutex> lock(_processMutex);
     return _state.store(stream);
 }
 
@@ -224,7 +224,7 @@ tresult PLUGIN_API SfizzVstProcessor::process(Vst::ProcessData& data)
     for (unsigned c = 0; c < numChannels; ++c)
         outputs[c] = data.outputs[0].channelBuffers32[c];
 
-    std::unique_lock<std::mutex> lock(_processMutex, std::try_to_lock);
+    std::unique_lock<SpinMutex> lock(_processMutex, std::try_to_lock);
 
     if (!lock.owns_lock()) {
         for (unsigned c = 0; c < numChannels; ++c)
@@ -515,7 +515,7 @@ tresult PLUGIN_API SfizzVstProcessor::notify(Vst::IMessage* message)
         if (result != kResultTrue)
             return result;
 
-        std::unique_lock<std::mutex> lock(_processMutex);
+        std::unique_lock<SpinMutex> lock(_processMutex);
         _state.sfzFile.assign(static_cast<const char *>(data), size);
         loadSfzFileOrDefault(*_synth, _state.sfzFile);
         lock.unlock();
@@ -533,7 +533,7 @@ tresult PLUGIN_API SfizzVstProcessor::notify(Vst::IMessage* message)
         if (result != kResultTrue)
             return result;
 
-        std::unique_lock<std::mutex> lock(_processMutex);
+        std::unique_lock<SpinMutex> lock(_processMutex);
         _state.scalaFile.assign(static_cast<const char *>(data), size);
         _synth->loadScalaFile(_state.scalaFile);
         lock.unlock();
@@ -601,23 +601,28 @@ void SfizzVstProcessor::doBackgroundWork()
 
         if (!std::strcmp(id, "SetNumVoices")) {
             int32 value = *msg->payload<int32>();
+            std::lock_guard<SpinMutex> lock(_processMutex);
             _synth->setNumVoices(value);
         }
         else if (!std::strcmp(id, "SetOversampling")) {
             int32 value = *msg->payload<int32>();
+            std::lock_guard<SpinMutex> lock(_processMutex);
             _synth->setOversamplingFactor(1 << value);
         }
         else if (!std::strcmp(id, "SetPreloadSize")) {
             int32 value = *msg->payload<int32>();
+            std::lock_guard<SpinMutex> lock(_processMutex);
             _synth->setPreloadSize(value);
         }
         else if (!std::strcmp(id, "CheckShouldReload")) {
             if (_synth->shouldReloadFile()) {
                 fprintf(stderr, "[Sfizz] sfz file has changed, reloading\n");
+                std::lock_guard<SpinMutex> lock(_processMutex);
                 loadSfzFileOrDefault(*_synth, _state.sfzFile);
             }
             else if (_synth->shouldReloadScala()) {
                 fprintf(stderr, "[Sfizz] scala file has changed, reloading\n");
+                std::lock_guard<SpinMutex> lock(_processMutex);
                 _synth->loadScalaFile(_state.scalaFile);
             }
         }
diff --git a/vst/SfizzVstProcessor.h b/vst/SfizzVstProcessor.h
index bbbf7490..e8408169 100644
--- a/vst/SfizzVstProcessor.h
+++ b/vst/SfizzVstProcessor.h
@@ -10,8 +10,8 @@
 #include "ring_buffer/ring_buffer.h"
 #include "public.sdk/source/vst/vstaudioeffect.h"
 #include <sfizz.hpp>
+#include <SpinMutex.h>
 #include <thread>
-#include <mutex>
 #include <memory>
 #include <cstdlib>
 
@@ -65,7 +65,7 @@ private:
     Ring_Buffer _fifoToWorker;
     RTSemaphore _semaToWorker;
     Ring_Buffer _fifoMessageFromUi;
-    std::mutex _processMutex;
+    SpinMutex _processMutex;
 
     // file modification periodic checker
     uint32 _fileChangeCounter = 0;