add async with null sink bench

bench/utils.h

@@ -0,0 +1,35 @@
+//
+// Copyright(c) 2015 Gabi Melman.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+//
+
+#pragma once
+
+#include <sstream>
+#include <iomanip>
+#include <locale>
+
+namespace utils
+{
+
+template<typename T>
+inline std::string format(const T& value)
+{
+    static std::locale loc("");
+    std::stringstream ss;
+    ss.imbue(loc);
+    ss << value;
+    return ss.str();
+}
+
+template<>
+inline std::string format(const double & value)
+{
+    static std::locale loc("");
+    std::stringstream ss;
+    ss.imbue(loc);
+    ss << std::fixed << std::setprecision(1) << value;
+    return ss.str();
+}
+
+}