From 33f37847bc003ac17c80f30b24e2b83575c758da Mon Sep 17 00:00:00 2001
From: ed <eddavies95@gmail.com>
Date: Fri, 2 Apr 2021 14:37:17 +0100
Subject: [PATCH] VST:  Use RAII initialisation for JUCE GUI and
 SharedResourcePointer for MessageThread

---
 .../VST/juce_VST_Wrapper.cpp                  | 59 ++++++++--------
 .../utility/juce_LinuxMessageThread.h         | 67 +++++++++++++------
 2 files changed, 73 insertions(+), 53 deletions(-)

diff --git a/modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.cpp b/modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.cpp
index 4a01ec0b01..6c22a2918e 100644
--- a/modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.cpp
+++ b/modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.cpp
@@ -185,13 +185,12 @@ namespace
         return w;
     }
 
+    static int numActivePlugins = 0;
     static bool messageThreadIsDefinitelyCorrect = false;
 }
 
 #endif
 
-static Array<void*> activePlugins;
-
 //==============================================================================
 // Ableton Live host specific commands
 struct AbletonLiveHostSpecific
@@ -316,44 +315,35 @@ public:
             vstEffect.flags |= Vst2::effFlagsNoSoundInStop;
        #endif
 
-        activePlugins.add (this);
+       #if JUCE_WINDOWS
+        ++numActivePlugins;
+       #endif
     }
 
     ~JuceVSTWrapper() override
     {
         JUCE_AUTORELEASEPOOL
         {
-            {
-               #if JUCE_LINUX || JUCE_BSD
-                MessageManagerLock mmLock;
-               #endif
-                stopTimer();
-                deleteEditor (false);
+           #if JUCE_LINUX || JUCE_BSD
+            MessageManagerLock mmLock;
+           #endif
 
-                hasShutdown = true;
+            stopTimer();
+            deleteEditor (false);
 
-                delete processor;
-                processor = nullptr;
+            hasShutdown = true;
 
-                jassert (editorComp == nullptr);
+            delete processor;
+            processor = nullptr;
 
-                deleteTempChannels();
+            jassert (editorComp == nullptr);
 
-                jassert (activePlugins.contains (this));
-                activePlugins.removeFirstMatchingValue (this);
-            }
+            deleteTempChannels();
 
-            if (activePlugins.size() == 0)
-            {
-               #if JUCE_LINUX || JUCE_BSD
-                SharedMessageThread::deleteInstance();
-               #endif
-                shutdownJuce_GUI();
-
-               #if JUCE_WINDOWS
+           #if JUCE_WINDOWS
+            if (--numActivePlugins == 0)
                 messageThreadIsDefinitelyCorrect = false;
-               #endif
-            }
+           #endif
         }
     }
 
@@ -394,8 +384,6 @@ public:
         const int numMidiEventsComingIn = midiEvents.getNumEvents();
        #endif
 
-        jassert (activePlugins.contains (this));
-
         {
             const int numIn  = processor->getTotalNumInputChannels();
             const int numOut = processor->getTotalNumOutputChannels();
@@ -2044,6 +2032,12 @@ private:
     }
 
     //==============================================================================
+    ScopedJuceInitialiser_GUI libraryInitialiser;
+
+   #if JUCE_LINUX || JUCE_BSD
+    SharedResourcePointer<MessageThread> messageThread;
+   #endif
+
     Vst2::audioMasterCallback hostCallback;
     AudioProcessor* processor = {};
     double sampleRate = 44100.0;
@@ -2096,7 +2090,11 @@ namespace
     {
         JUCE_AUTORELEASEPOOL
         {
-            initialiseJuce_GUI();
+            ScopedJuceInitialiser_GUI libraryInitialiser;
+
+           #if JUCE_LINUX || JUCE_BSD
+            SharedResourcePointer<MessageThread> messageThread;
+           #endif
 
             try
             {
@@ -2164,7 +2162,6 @@ namespace
     {
         PluginHostType::jucePlugInClientCurrentWrapperType = AudioProcessor::wrapperType_VST;
 
-        SharedMessageThread::getInstance();
         return pluginEntryPoint (audioMaster);
     }
 
diff --git a/modules/juce_audio_plugin_client/utility/juce_LinuxMessageThread.h b/modules/juce_audio_plugin_client/utility/juce_LinuxMessageThread.h
index 327c0f4854..e0e2bc5f3d 100644
--- a/modules/juce_audio_plugin_client/utility/juce_LinuxMessageThread.h
+++ b/modules/juce_audio_plugin_client/utility/juce_LinuxMessageThread.h
@@ -25,47 +25,70 @@
 
 #if JUCE_LINUX || JUCE_BSD
 
+#include <thread>
+
 namespace juce
 {
 
-struct SharedMessageThread  : public Thread
+class MessageThread
 {
-    SharedMessageThread()  : Thread ("VstMessageThread")
+public:
+    MessageThread()
     {
-        startThread (7);
-
-        while (! initialised)
-            sleep (1);
+        startThread();
     }
 
-    ~SharedMessageThread() override
+    ~MessageThread()
     {
-        signalThreadShouldExit();
-        JUCEApplicationBase::quit();
-        waitForThreadToExit (5000);
-        clearSingletonInstance();
+        MessageManager::getInstance()->stopDispatchLoop();
+        stopThread();
     }
 
-    void run() override
+    void startThread()
     {
-        initialiseJuce_GUI();
-        initialised = true;
+        shouldExit = false;
 
-        MessageManager::getInstance()->setCurrentThreadAsMessageThread();
+        thread = std::thread { [this]
+        {
+            Thread::setCurrentThreadPriority (7);
+            Thread::setCurrentThreadName ("JUCE Plugin Message Thread");
 
-        XWindowSystem::getInstance();
+            MessageManager::getInstance()->setCurrentThreadAsMessageThread();
+            XWindowSystem::getInstance();
 
-        while ((! threadShouldExit()) && MessageManager::getInstance()->runDispatchLoopUntil (250))
-        {}
+            threadInitialised.signal();
+
+            for (;;)
+            {
+                if (shouldExit
+                    || ! MessageManager::getInstance()->runDispatchLoopUntil (250))
+                {
+                    break;
+                }
+            }
+        } };
+
+        threadInitialised.wait();
     }
 
-    JUCE_DECLARE_SINGLETON (SharedMessageThread, false)
+    void stopThread()
+    {
+        shouldExit = true;
+        thread.join();
+    }
 
-    bool initialised = false;
+    bool isThreadRunning() const noexcept  { return thread.joinable(); }
+
+private:
+    WaitableEvent threadInitialised;
+    std::thread thread;
+
+    std::atomic<bool> shouldExit { false };
+
+    JUCE_DECLARE_NON_MOVEABLE (MessageThread)
+    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (MessageThread)
 };
 
-JUCE_IMPLEMENT_SINGLETON (SharedMessageThread)
-
 } // namespace juce
 
 #endif