STARLIGHT code and interface

[u/mrichter/AliRoot.git] / STARLIGHT / starlight / include / singleton.h

diff --git a/STARLIGHT/starlight/include/singleton.h b/STARLIGHT/starlight/include/singleton.h
new file mode 100644 (file)
index 0000000..4227311
--- /dev/null
+++ b/STARLIGHT/starlight/include/singleton.h
@@ -0,0 +1,71 @@
+#ifndef SINGLETON_H
+#define SINGLETON_H
+
+#ifdef CPP11
+#include <atomic>
+#include <mutex>
+
+
+template<class T>
+class Singleton {
+public:
+  static T& instance()
+  {
+    T * tmp = instance_.load(std::memory_order_consume);
+    if (!tmp) {
+      std::lock_guard<std::mutex> guard(instantiation_mutex);
+      tmp = instance_.load(std::memory_order_consume);
+      if (!tmp) {
+        tmp = new T;
+        instance_.store(tmp, std::memory_order_release);
+      }
+    }
+    return *tmp;
+  }
+private:
+  static std::atomic<T *> instance_;
+  static std::mutex instantiation_mutex;
+};
+
+template<class T>
+std::atomic<T *> Singleton<T>::instance_(0);
+
+template<class T>
+std::mutex Singleton<T>::instantiation_mutex;
+
+#else
+
+#include "slmutex.h"
+
+template<class T>
+class Singleton {
+public:
+  static T& instance()
+  {
+    T *tmp = _instance;
+    if (!tmp) {
+      Lockguard<MutexPosix> guard(&_instantiation_mutex);
+      if (!tmp) {
+        tmp = new T;
+       _instance = tmp;
+      }
+    }
+    return *tmp;
+  }
+private:
+  
+  static T * _instance;
+  
+  static MutexPosix _instantiation_mutex;
+  
+};
+
+template<class T>
+T *Singleton<T>::_instance(0);
+
+template<class T>
+MutexPosix Singleton<T>::_instantiation_mutex;
+
+#endif
+
+#endif