Remove singleton behavior for Reflection Plugin Class (#370)

* Implement protostring in singleton reflection plugin class

* Created separate singleton class to save protostring

* Added deleteinstance function to ProtoDescriptorString to free memory when all server stops

* Removed extra comment

* Improved code structure

* Reverted lv_interop

* Reverted lv_interop.cc and lv_interop.h

src/grpc_server.cc

@@ -270,6 +270,44 @@ namespace grpc_labview
 
             _server = nullptr;
         }
-        LVProtoServerReflectionPlugin::GetInstance()->DeleteInstance();
-    }    
+        grpc_labview::ProtoDescriptorString::getInstance()->deleteInstance();
+    }
+
+    //---------------------------------------------------------------------
+    //---------------------------------------------------------------------
+
+    // Initialize the static members
+    ProtoDescriptorString* ProtoDescriptorString::m_instance = nullptr;
+    std::mutex ProtoDescriptorString::m_mutex;
+
+    // Return the static class instance. Thread safe.
+    ProtoDescriptorString* ProtoDescriptorString::getInstance() {
+        std::unique_lock<std::mutex> lock(m_mutex);
+        if (m_instance == nullptr) {
+            m_instance = new ProtoDescriptorString();
+        }
+        return m_instance;
+    }
+
+    // Get the descriptor string
+    std::string ProtoDescriptorString::getDescriptor() {
+        std::unique_lock<std::mutex> lock(m_mutex);
+        return m_descriptor;
+    }
+
+    // Set the descriptor string
+    void ProtoDescriptorString::setDescriptor(std::string str) {
+        std::unique_lock<std::mutex> lock(m_mutex);
+        m_refcount++;
+        m_descriptor = str;
+    }
+
+    // Delete the instaance based on the refcount
+    void ProtoDescriptorString::deleteInstance() {
+        std::unique_lock<std::mutex> lock(m_mutex);
+        if (!--m_refcount) {
+            delete m_instance;
+            m_instance = nullptr;
+        }
+    }
 }

src/grpc_server.h

@@ -237,4 +237,35 @@ namespace grpc_labview
     void OccurServerEvent(LVUserEventRef event, gRPCid* data);
     void OccurServerEvent(LVUserEventRef event, gRPCid* data, std::string eventMethodName);
     std::string read_keycert(const std::string &filename);
+
+    //---------------------------------------------------------------------
+    //---------------------------------------------------------------------
+    class ProtoDescriptorString {
+        // Static members
+        static ProtoDescriptorString* m_instance;
+        static std::mutex m_mutex;
+
+        // Non static members
+        std::string m_descriptor;
+        int m_refcount = 0; // Not a normal refcount. Its counts the number of time we set the descriptor string.
+
+        // Default private constructor to prevent instantiation
+        ProtoDescriptorString() = default;
+
+        // Delete copy constructor and assignment operator
+        ProtoDescriptorString(const ProtoDescriptorString&) = delete;
+        ProtoDescriptorString& operator=(const ProtoDescriptorString&) = delete;
+    public:
+        // Return the static class instance
+        static ProtoDescriptorString* getInstance();
+
+        // Set the descriptor string
+        void setDescriptor(std::string);
+
+        // Get the descriptor string
+        std::string getDescriptor();
+
+        // Delete the instance based on the refcount
+        void deleteInstance();
+    };
 }

src/lv_proto_server_reflection_plugin.cc

@@ -4,6 +4,7 @@
 #include <grpcpp/impl/server_initializer.h>
 #include <grpcpp/server_builder.h>
 #include <lv_interop.h>
+#include <grpc_server.h>
 //---------------------------------------------------------------------
 //---------------------------------------------------------------------
 using grpc::ServerContext;
@@ -13,8 +14,6 @@ using grpc::ServerBuilder;
 
 namespace grpc_labview
 {
-    LVProtoServerReflectionPlugin* LVProtoServerReflectionPlugin::m_instance = nullptr;
-
     LVProtoServerReflectionPlugin::LVProtoServerReflectionPlugin() : reflection_service_(new grpc_labview::LVProtoServerReflectionService()) {
     }
 
@@ -49,19 +48,11 @@ namespace grpc_labview
         reflection_service_.get()->AddFileDescriptorProto(serializedProto);
     }
 
-    LVProtoServerReflectionPlugin* LVProtoServerReflectionPlugin::GetInstance() {
-        if (m_instance == nullptr)        
-            m_instance = new LVProtoServerReflectionPlugin();
-        return m_instance;
-    }
-
-    void LVProtoServerReflectionPlugin::DeleteInstance() {
-        m_instance = nullptr;
-    }
-
     std::unique_ptr< ::grpc::ServerBuilderPlugin> CreateLVProtoReflection() {
-        return std::unique_ptr< ::grpc::ServerBuilderPlugin>(
-            LVProtoServerReflectionPlugin::GetInstance());
+
+        LVProtoServerReflectionPlugin* reflectionPluginInstance = new LVProtoServerReflectionPlugin();
+        reflectionPluginInstance->AddFileDescriptorProto(grpc_labview::ProtoDescriptorString::getInstance()->getDescriptor());
+        return std::unique_ptr< ::grpc::ServerBuilderPlugin>(reflectionPluginInstance);
     }
 
     void InitLVProtoReflectionServerBuilderPlugin() {
@@ -75,6 +66,6 @@ namespace grpc_labview
     LIBRARY_EXPORT void DeserializeReflectionInfo(grpc_labview::LStrHandle serializedFileDescriptor)
     {
         std::string serializedDescriptorStr = grpc_labview::GetLVString(serializedFileDescriptor);
-        LVProtoServerReflectionPlugin::GetInstance()->AddFileDescriptorProto(serializedDescriptorStr);
+        grpc_labview::ProtoDescriptorString::getInstance()->setDescriptor(serializedDescriptorStr);
     }
 }

src/lv_proto_server_reflection_plugin.h

@@ -39,6 +39,7 @@ namespace grpc_labview
 {
     class LVProtoServerReflectionPlugin : public ::grpc::ServerBuilderPlugin {
     public:
+        LVProtoServerReflectionPlugin();
         ::std::string name() override;
         void InitServer(ServerInitializer* si) override;
         void Finish(ServerInitializer* si) override;
@@ -47,12 +48,8 @@ namespace grpc_labview
         bool has_sync_methods() const override;
         void AddService(std::string serviceName);
         void AddFileDescriptorProto(const std::string& serializedProto);
-        static LVProtoServerReflectionPlugin* GetInstance();
-        void DeleteInstance();
 
     private:
-        LVProtoServerReflectionPlugin(); // hide constructors TODO
-        static LVProtoServerReflectionPlugin* m_instance;
         std::shared_ptr<grpc_labview::LVProtoServerReflectionService> reflection_service_;
     };