From a06a220866b9f082b5a29ffc63968f1ab4798814 Mon Sep 17 00:00:00 2001
From: Jean Pierre Cimalando <jp-dev@inbox.ru>
Date: Wed, 3 Feb 2021 18:10:18 +0100
Subject: [PATCH] Fix a crash that makes VST fail pluginval

---
 vst/SfizzVstProcessor.cpp | 18 +++++++++++++++---
 vst/SfizzVstProcessor.h   |  2 ++
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/vst/SfizzVstProcessor.cpp b/vst/SfizzVstProcessor.cpp
index 6a22e52f..ec1d77d0 100644
--- a/vst/SfizzVstProcessor.cpp
+++ b/vst/SfizzVstProcessor.cpp
@@ -182,6 +182,9 @@ tresult PLUGIN_API SfizzVstProcessor::setActive(TBool state)
 {
     sfz::Sfizz* synth = _synth.get();
 
+    if (bool(state) == _isActive)
+        return kResultTrue;
+
     if (!synth)
         return kResultFalse;
 
@@ -192,13 +195,13 @@ tresult PLUGIN_API SfizzVstProcessor::setActive(TBool state)
         _fileChangePeriod = static_cast<uint32>(1.0 * processSetup.sampleRate);
         _playStateChangePeriod = static_cast<uint32>(50e-3 * processSetup.sampleRate);
 
-        _workRunning = true;
-        _worker = std::thread([this]() { doBackgroundWork(); });
+        startBackgroundWork();
     } else {
-        synth->allSoundOff();
         stopBackgroundWork();
+        synth->allSoundOff();
     }
 
+    _isActive = bool(state);
     return kResultTrue;
 }
 
@@ -642,6 +645,15 @@ void SfizzVstProcessor::doBackgroundWork()
     }
 }
 
+void SfizzVstProcessor::startBackgroundWork()
+{
+    if (_workRunning)
+        return;
+
+    _workRunning = true;
+    _worker = std::thread([this]() { doBackgroundWork(); });
+}
+
 void SfizzVstProcessor::stopBackgroundWork()
 {
     if (!_workRunning)
diff --git a/vst/SfizzVstProcessor.h b/vst/SfizzVstProcessor.h
index e8408169..1401780b 100644
--- a/vst/SfizzVstProcessor.h
+++ b/vst/SfizzVstProcessor.h
@@ -48,6 +48,7 @@ public:
 private:
     // synth state. acquire processMutex before accessing
     std::unique_ptr<sfz::Sfizz> _synth;
+    bool _isActive = false;
     SfizzVstState _state;
     float _currentStretchedTuning = 0;
 
@@ -94,6 +95,7 @@ private:
 
     // worker
     void doBackgroundWork();
+    void startBackgroundWork();
     void stopBackgroundWork();
     // writer
     bool writeWorkerMessage(const char* type, const void* data, uintptr_t size);