created a generic crtp class for handling singletons. I am using that class for the logmap now

lib/include/srslte/common/logmap.h

@@ -20,6 +20,7 @@
  */
 
 #include "logger.h"
+#include "singleton.h"
 #include <mutex>
 #include <unordered_map>
 
@@ -30,10 +31,11 @@ namespace srslte {
 
 class log_filter;
 
-class logmap
+class logmap : public singleton_t<logmap>
 {
 public:
   // Access to log map by servicename. If servicename does not exist, create a new log_filter with default cfg
+  // Access to the map is protected by a mutex
   static log* get(const std::string& servicename)
   {
     logmap*                     pool = get_instance();
@@ -51,12 +53,6 @@ public:
     return it->second.get();
   }
 
-  static logmap* get_instance()
-  {
-    static logmap* instance = new logmap{};
-    return instance;
-  }
-
   // set default logger
   void set_default_logger(logger* logger_)
   {
@@ -91,9 +87,10 @@ public:
     return log_map.erase(servicename) > 0;
   }
 
-private:
+protected:
   logmap() : default_logger(&logger_stdout_val) {}
 
+private:
   // consts
   logger_stdout logger_stdout_val;
 

lib/include/srslte/common/singleton.h

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2013-2019 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#ifndef SRSLTE_SINGLETON_H
+#define SRSLTE_SINGLETON_H
+
+// CRTP pattern to create class singletons
+template <typename T>
+class singleton_t
+{
+public:
+  singleton_t(const singleton_t<T>&) = delete;
+  singleton_t(singleton_t<T>&&)      = delete;
+  singleton_t& operator=(const singleton_t<T>&) = delete;
+  singleton_t& operator=(singleton_t<T>&&) = delete;
+
+  static T* get_instance()
+  {
+    // this variable initialization is thread-safe since C++11
+    // instance dtor is called on program exit
+    static std::unique_ptr<T> instance{new T_instance{}};
+    return instance.get();
+  }
+
+protected:
+  singleton_t() = default;
+
+private:
+  // this class makes the protected T::T() accessible to the singleton
+  struct T_instance : public T {
+    T_instance() : T() {}
+  };
+};
+
+#endif // SRSLTE_SINGLETON_H