core: time::Duration, time:Point, time::now

refs #1148

Change-Id: I19c3d2f9b638797a6a36ce41a98be4463b4b7a2d
diff --git a/daemon/core/time.hpp b/daemon/core/time.hpp
new file mode 100644
index 0000000..1299ab4
--- /dev/null
+++ b/daemon/core/time.hpp
@@ -0,0 +1,34 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (C) 2014 Named Data Networking Project
+ * See COPYING for copyright and distribution information.
+ */
+
+#ifndef NFD_CORE_TIME_H
+#define NFD_CORE_TIME_H
+
+#include "common.hpp"
+
+namespace ndn {
+namespace time {
+
+/** \class Duration
+ *  \brief represents a time interval
+ *  Time unit is nanosecond.
+ */
+typedef int64_t Duration;
+
+/** \class Point
+ *  \brief represents a point in time
+ *  This uses monotonic clock.
+ */
+typedef Duration Point;
+
+/// \return{ the current time in monotonic clock }
+Point
+now();
+
+} // namespace time
+} // namespace ndn
+
+#endif // NFD_CORE_TIME_H