Don't lockup host UI when changing zita plugin params

source/native-plugins/zita-at1.cpp

@@ -41,6 +41,7 @@ using namespace AT1;
 // AT1 Plugin
 
 class AT1Plugin : public NativePluginClass,
+                  public X_handler_thread<Mainwin>::SetValueCallback,
                   private Mainwin::ValueChangedCallback
 {
 public:
@@ -68,7 +69,7 @@ public:
           rootwin(nullptr),
           mainwin(nullptr),
           handler(nullptr),
-          handlerThread(),
+          handlerThread(this),
           leakDetector_AT1Plugin()
     {
         CARLA_SAFE_ASSERT(host != nullptr);
@@ -347,18 +348,7 @@ public:
         if (mainwin == nullptr)
             return;
 
-        const CarlaMutexLocker cml(handlerThread.getLock());
-
-        if (index < kParameterNROTARY)
-        {
-            mainwin->_rotary[index]->set_value(value);
-            return;
-        }
-        if (index == kParameterM_CHANNEL)
-        {
-            mainwin->setchan_ui(value);
-            return;
-        }
+        handlerThread.setParameterValueLater(index, value);
     }
 
     // -------------------------------------------------------------------
@@ -396,6 +386,25 @@ public:
     }
 
     // -------------------------------------------------------------------
+    // X_handler_thread callbacks
+
+    void setParameterValueFromHandlerThread(uint32_t index, float value) override
+    {
+        CARLA_SAFE_ASSERT_RETURN(mainwin != nullptr,);
+
+        if (index < kParameterNROTARY)
+        {
+            mainwin->_rotary[index]->set_value(value);
+            return;
+        }
+        if (index == kParameterM_CHANNEL)
+        {
+            mainwin->setchan_ui(value);
+            return;
+        }
+    }
+
+    // -------------------------------------------------------------------
 
 private:
     // Fake jack client

source/native-plugins/zita-bls1.cpp

@@ -41,6 +41,7 @@ using namespace BLS1;
 // BLS1 Plugin
 
 class BLS1Plugin : public NativePluginClass,
+                   public X_handler_thread<Mainwin>::SetValueCallback,
                    private Mainwin::ValueChangedCallback
 {
 public:
@@ -66,7 +67,7 @@ public:
           rootwin(nullptr),
           mainwin(nullptr),
           handler(nullptr),
-          handlerThread(),
+          handlerThread(this),
           leakDetector_BLS1Plugin()
     {
         CARLA_SAFE_ASSERT(host != nullptr);
@@ -306,9 +307,7 @@ public:
         if (mainwin == nullptr)
             return;
 
-        const CarlaMutexLocker cml(handlerThread.getLock());
-
-        mainwin->_rotary[index]->set_value(value);
+        handlerThread.setParameterValueLater(index, value);
     }
 
     // -------------------------------------------------------------------
@@ -346,6 +345,16 @@ public:
     }
 
     // -------------------------------------------------------------------
+    // X_handler_thread callbacks
+
+    void setParameterValueFromHandlerThread(uint32_t index, float value) override
+    {
+        CARLA_SAFE_ASSERT_RETURN(mainwin != nullptr,);
+
+        mainwin->_rotary[index]->set_value(value);
+    }
+
+    // -------------------------------------------------------------------
 
 private:
     // Fake jack client

source/native-plugins/zita-common.hpp

@@ -20,6 +20,7 @@
 
 #include "CarlaMutex.hpp"
 #include "CarlaThread.hpp"
+#include "LinkedList.hpp"
 
 #include <png.h>
 #include <clxclient.h>
@@ -29,17 +30,32 @@
 
 // -----------------------------------------------------------------------
 
+struct X_handler_Param {
+    uint32_t index;
+    float value;
+};
+
+typedef LinkedList<X_handler_Param> ParamList;
+
 template<class MainwinType>
 class X_handler_thread : public CarlaThread
 {
 public:
-    X_handler_thread()
+    struct SetValueCallback {
+        virtual ~SetValueCallback() {}
+        virtual void setParameterValueFromHandlerThread(const uint32_t index, const float value) = 0;
+    };
+
+    X_handler_thread(SetValueCallback* const cb)
         : CarlaThread("X_handler"),
+          fCallback(cb),
           fMutex(),
           fHandler(nullptr),
           fRootwin(nullptr),
           fMainwin(nullptr),
-          fClosed(false) {}
+          fClosed(false),
+          fParamMutex(),
+          fParamChanges() {}
 
     void setupAndRun(X_handler* const h, X_rootwin* const r, MainwinType* const m) noexcept
     {
@@ -71,6 +87,14 @@ public:
         return fMutex;
     }
 
+    void setParameterValueLater(const uint32_t index, const float value) noexcept
+    {
+        const CarlaMutexLocker cml(fParamMutex);
+
+        const X_handler_Param param = { index, value };
+        fParamChanges.append(param);
+    }
+
     bool wasClosed() noexcept
     {
         if (fClosed)
@@ -82,12 +106,17 @@ public:
     }
 
 private:
+    SetValueCallback* const fCallback;
+
     CarlaMutex    fMutex;
     X_handler*    fHandler;
     X_rootwin*    fRootwin;
     MainwinType*  fMainwin;
     volatile bool fClosed;
 
+    CarlaMutex fParamMutex;
+    ParamList  fParamChanges;
+
     void run() override
     {
         for (; ! shouldThreadExit();)
@@ -99,6 +128,18 @@ private:
 
                 CARLA_SAFE_ASSERT_RETURN(fMainwin != nullptr,);
 
+                {
+                    const CarlaMutexLocker cml(fParamMutex);
+
+                    for (ParamList::Itenerator it = fParamChanges.begin(); it.valid(); it.next())
+                    {
+                        const X_handler_Param& param(it.getValue());
+                        fCallback->setParameterValueFromHandlerThread(param.index, param.value);
+                    }
+
+                    fParamChanges.clear();
+                }
+
                 for (; (ev = fMainwin->process()) == EV_X11;)
                 {
                     fRootwin->handle_event();

source/native-plugins/zita-rev1.cpp

@@ -40,6 +40,7 @@ using namespace REV1;
 // REV1 Plugin
 
 class REV1Plugin : public NativePluginClass,
+                   public X_handler_thread<Mainwin>::SetValueCallback,
                    private Mainwin::ValueChangedCallback
 {
 public:
@@ -69,7 +70,7 @@ public:
           rootwin(nullptr),
           mainwin(nullptr),
           handler(nullptr),
-          handlerThread(),
+          handlerThread(this),
           leakDetector_REV1Plugin()
     {
         CARLA_SAFE_ASSERT(host != nullptr);
@@ -387,14 +388,7 @@ public:
         if (mainwin == nullptr)
             return;
 
-        uint32_t rindex = index;
-
-        if (kIsAmbisonic && index == kParameterOPMIXorRGXYZ)
-            rindex += 1;
-
-        const CarlaMutexLocker cml(handlerThread.getLock());
-
-        mainwin->_rotary[rindex]->set_value(value);
+        handlerThread.setParameterValueLater(index, value);
     }
 
     // -------------------------------------------------------------------
@@ -437,6 +431,21 @@ public:
     }
 
     // -------------------------------------------------------------------
+    // X_handler_thread callbacks
+
+    void setParameterValueFromHandlerThread(uint32_t index, float value) override
+    {
+        CARLA_SAFE_ASSERT_RETURN(mainwin != nullptr,);
+
+        uint32_t rindex = index;
+
+        if (kIsAmbisonic && index == kParameterOPMIXorRGXYZ)
+            rindex += 1;
+
+        mainwin->_rotary[rindex]->set_value(value);
+    }
+
+    // -------------------------------------------------------------------
 
 private:
     const bool     kIsAmbisonic;