Don't call engine->idle if engine is plugin; Give plugin hosts idle

source/backend/engine/CarlaEngineNative.cpp

@@ -700,6 +700,14 @@ protected:
         return "Plugin";
     }
 
+    void callback(const EngineCallbackOpcode action, const uint pluginId, const int value1, const int value2, const float value3, const char* const valueStr) noexcept override
+    {
+        CarlaEngine::callback(action, pluginId, value1, value2, value3, valueStr);
+
+        if (action == ENGINE_CALLBACK_IDLE)
+            pHost->dispatcher(pHost->handle, NATIVE_HOST_OPCODE_HOST_IDLE, 0, 0, nullptr, 0.0f);
+    }
+
     // -------------------------------------------------------------------
 
     const char* renamePlugin(const uint id, const char* const newName) override

source/backend/plugin/CarlaPluginBridge.cpp

@@ -2531,10 +2531,15 @@ public:
 #endif
         sFirstInit = false;
 
+        const bool needsEngineIdle = pData->engine->getType() != kEngineTypePlugin;
+
         for (; Time::currentTimeMillis() < fLastPongTime + timeoutEnd && fBridgeThread.isThreadRunning();)
         {
             pData->engine->callback(ENGINE_CALLBACK_IDLE, 0, 0, 0, 0.0f, nullptr);
-            pData->engine->idle();
+
+            if (needsEngineIdle)
+                pData->engine->idle();
+
             idle();
 
             if (fInitiated)

source/backend/plugin/CarlaPluginNative.cpp

@@ -2219,6 +2219,9 @@ protected:
             pData->engine->callback(ENGINE_CALLBACK_UI_STATE_CHANGED, pData->id, -1, 0, 0.0f, nullptr);
             fIsUiVisible = false;
             break;
+        case NATIVE_HOST_OPCODE_HOST_IDLE:
+            pData->engine->callback(ENGINE_CALLBACK_IDLE, 0, 0, 0, 0.0f, nullptr);
+            break;
         }
 
         return ret;

source/includes/CarlaNative.h

@@ -103,7 +103,8 @@ typedef enum {
     NATIVE_HOST_OPCODE_RELOAD_PARAMETERS     = 3, /** nothing                                           */
     NATIVE_HOST_OPCODE_RELOAD_MIDI_PROGRAMS  = 4, /** nothing                                           */
     NATIVE_HOST_OPCODE_RELOAD_ALL            = 5, /** nothing                                           */
-    NATIVE_HOST_OPCODE_UI_UNAVAILABLE        = 6  /** nothing                                           */
+    NATIVE_HOST_OPCODE_UI_UNAVAILABLE        = 6, /** nothing                                           */
+    NATIVE_HOST_OPCODE_HOST_IDLE             = 7  /** nothing                                           */
 } NativeHostDispatcherOpcode;
 
 /* ------------------------------------------------------------------------------------------------------------

source/plugin/carla-lv2.cpp

@@ -897,6 +897,7 @@ protected:
         case NATIVE_HOST_OPCODE_RELOAD_PARAMETERS:
         case NATIVE_HOST_OPCODE_RELOAD_MIDI_PROGRAMS:
         case NATIVE_HOST_OPCODE_RELOAD_ALL:
+        case NATIVE_HOST_OPCODE_HOST_IDLE:
             // nothing
             break;
         case NATIVE_HOST_OPCODE_UI_UNAVAILABLE:

source/plugin/carla-vst.cpp

@@ -512,10 +512,27 @@ protected:
     intptr_t handleDispatcher(const NativeHostDispatcherOpcode opcode, const int32_t index, const intptr_t value, void* const ptr, const float opt)
     {
         carla_debug("NativePlugin::handleDispatcher(%i, %i, " P_INTPTR ", %p, %f)", opcode, index, value, ptr, opt);
-        return 0;
+
+        switch (opcode)
+        {
+        case NATIVE_HOST_OPCODE_NULL:
+        case NATIVE_HOST_OPCODE_UPDATE_PARAMETER:
+        case NATIVE_HOST_OPCODE_UPDATE_MIDI_PROGRAM:
+        case NATIVE_HOST_OPCODE_RELOAD_PARAMETERS:
+        case NATIVE_HOST_OPCODE_RELOAD_MIDI_PROGRAMS:
+        case NATIVE_HOST_OPCODE_RELOAD_ALL:
+        case NATIVE_HOST_OPCODE_UI_UNAVAILABLE:
+            break;
+
+        case NATIVE_HOST_OPCODE_HOST_IDLE:
+            fAudioMaster(fEffect, audioMasterIdle, 0, 0, nullptr, 0.0f);
+            break;
+        }
 
         // unused for now
-        (void)opcode; (void)index; (void)value; (void)ptr; (void)opt;
+        return 0;
+
+        (void)index; (void)value; (void)ptr; (void)opt;
     }
 
 private: