reduce total number of open file handles held at any given time

include/utilities/FileStreamHandler.hpp

@@ -8,13 +8,26 @@ namespace utils
     class FileStreamHandler : public StreamHandler
     {
       public:
-            FileStreamHandler(const char* path) : StreamHandler()
+            FileStreamHandler(const char* path) : StreamHandler(), path(path)
             {
-                auto stream = std::make_shared<std::ofstream>();
-                stream->open(path, std::ios::trunc);
+                stream = std::make_shared<std::ofstream>();
+                stream->open(path, std::ios::trunc); //clear any existing data
+                stream->close(); //avoid too many open files
                 output_stream = stream;
             }
             virtual ~FileStreamHandler(){}
+
+            template<class DataType> std::ostream& operator<<(const DataType& val)
+            {
+                if( !stream->is_open() ) 
+                    stream->open(path, std::ios_base::app);
+                put(val);
+                stream->close();
+                return *output_stream;
+            }
+      private:
+        std::string path;
+        std::shared_ptr<std::ofstream> stream;
     };
 
 }