Enable patchbay engine mode in settings; Fix ScopedActionLock

resources/ui/carla_settings.ui

@@ -741,6 +741,11 @@
                     <string>Continuous Rack</string>
                    </property>
                   </item>
+                  <item>
+                   <property name="text">
+                    <string>Patchbay (EXPERIMENTAL)</string>
+                   </property>
+                  </item>
                  </widget>
                 </item>
                </layout>
@@ -757,7 +762,12 @@
                  <widget class="QComboBox" name="cb_engine_process_mode_other">
                   <item>
                    <property name="text">
-                    <string>Continuous Rack (EXPERIMENTAL)</string>
+                    <string>Continuous Rack</string>
+                   </property>
+                  </item>
+                  <item>
+                   <property name="text">
+                    <string>Patchbay (EXPERIMENTAL)</string>
                    </property>
                   </item>
                  </widget>

source/backend/engine/CarlaEngine.cpp

@@ -594,7 +594,7 @@ bool CarlaEngine::removePlugin(const uint id)
     pData->thread.stopThread(500);
 
 #ifndef BUILD_BRIDGE
-    const bool lockWait(isRunning() && pData->options.processMode != ENGINE_PROCESS_MODE_MULTIPLE_CLIENTS);
+    const bool lockWait(isRunning() /*&& pData->options.processMode != ENGINE_PROCESS_MODE_MULTIPLE_CLIENTS*/);
     const ScopedActionLock sal(pData, kEnginePostActionRemovePlugin, id, 0, lockWait);
 
     for (uint i=id; i < pData->curPluginCount; ++i)
@@ -604,6 +604,9 @@ bool CarlaEngine::removePlugin(const uint id)
         plugin2->updateOscURL();
     }
 
+    if (pData->options.processMode == ENGINE_PROCESS_MODE_PATCHBAY)
+        pData->graph.removePlugin(plugin);
+
     if (isOscControlRegistered())
         oscSend_control_remove_plugin(id);
 #else
@@ -611,9 +614,6 @@ bool CarlaEngine::removePlugin(const uint id)
     carla_zeroStruct(pData->plugins, 1);
 #endif
 
-    if (pData->options.processMode == ENGINE_PROCESS_MODE_PATCHBAY)
-        pData->graph.removePlugin(plugin);
-
     delete plugin;
 
     if (isRunning() && ! pData->aboutToClose)
@@ -777,7 +777,7 @@ bool CarlaEngine::switchPlugins(const uint idA, const uint idB) noexcept
 
     pData->thread.stopThread(500);
 
-    const bool lockWait(isRunning() && pData->options.processMode != ENGINE_PROCESS_MODE_MULTIPLE_CLIENTS);
+    const bool lockWait(isRunning() /*&& pData->options.processMode != ENGINE_PROCESS_MODE_MULTIPLE_CLIENTS*/);
     const ScopedActionLock sal(pData, kEnginePostActionSwitchPlugins, idA, idB, lockWait);
 
     CarlaPlugin* const pluginA(pData->plugins[idA].plugin);

source/backend/engine/CarlaEngineGraph.cpp

@@ -940,6 +940,9 @@ public:
 
         if (const int numChan = audio.getNumChannels())
         {
+            if (fPlugin->getAudioInCount() == 0)
+                audio.clear();
+
             float* audioBuffers[numChan];
 
             for (int i=0; i<numChan; ++i)
@@ -983,10 +986,11 @@ public:
 
         if (CarlaEngineEventPort* const port = fPlugin->getDefaultEventOutPort())
         {
-            const EngineEvent* const engineEvents(port->fBuffer);
+            /*const*/ EngineEvent* const engineEvents(port->fBuffer);
             CARLA_SAFE_ASSERT_RETURN(engineEvents != nullptr,);
 
             fillJuceMidiBufferFromEngineEvents(midi, engineEvents);
+            carla_zeroStruct<EngineEvent>(engineEvents, kMaxEngineEventInternalCount);
         }
     }
 
@@ -1175,10 +1179,8 @@ void PatchbayGraph::removePlugin(CarlaPlugin* const plugin)
     // TODO
     //removePluginFromPatchbay(plugin);
 
-    graph.removeNode(plugin->getPatchbayNodeId());
-
     // Fix plugin Ids properties
-    for (uint i=plugin->getId(), count=engine->getCurrentPluginCount(); i<count; ++i)
+    for (uint i=0, count=engine->getCurrentPluginCount(); i<count; ++i)
     {
         CarlaPlugin* const plugin2(engine->getPlugin(i));
         CARLA_SAFE_ASSERT_BREAK(plugin2 != nullptr);
@@ -1189,6 +1191,8 @@ void PatchbayGraph::removePlugin(CarlaPlugin* const plugin)
             node->properties.set("pluginId", static_cast<int>(plugin2->getId()));
         }
     }
+
+    CARLA_SAFE_ASSERT_RETURN(graph.removeNode(plugin->getPatchbayNodeId()),);
 }
 
 void PatchbayGraph::removeAllPlugins()

source/backend/engine/CarlaEngineInternal.cpp

@@ -331,9 +331,12 @@ void CarlaEngine::ProtectedData::doNextPluginAction(const bool unlock) noexcept
 ScopedActionLock::ScopedActionLock(CarlaEngine::ProtectedData* const data, const EnginePostAction action, const uint pluginId, const uint value, const bool lockWait) noexcept
     : fData(data)
 {
-    CARLA_SAFE_ASSERT_RETURN(fData->nextAction.opcode == kEnginePostActionNull,);
     CARLA_SAFE_ASSERT_RETURN(action != kEnginePostActionNull,);
 
+    fData->nextAction.mutex.lock();
+
+    CARLA_SAFE_ASSERT_RETURN(fData->nextAction.opcode == kEnginePostActionNull,);
+
     fData->nextAction.opcode   = action;
     fData->nextAction.pluginId = pluginId;
     fData->nextAction.value    = value;
@@ -353,6 +356,7 @@ ScopedActionLock::ScopedActionLock(CarlaEngine::ProtectedData* const data, const
 
 ScopedActionLock::~ScopedActionLock() noexcept
 {
+    CARLA_SAFE_ASSERT(fData->nextAction.opcode == kEnginePostActionNull);
     fData->nextAction.mutex.unlock();
 }