NEW FILE HEADER / COPYRIGHT FORMAT

[senf.git] / Scheduler / ClockService.hh

diff --git a/Scheduler/ClockService.hh b/Scheduler/ClockService.hh
index 6ad51b5..77f0f6a 100644 (file)
--- a/Scheduler/ClockService.hh
+++ b/Scheduler/ClockService.hh
@@ -1,8 +1,8 @@
 // $Id$
 //
 // Copyright (C) 2007 
-// Fraunhofer Institut fuer offene Kommunikationssysteme (FOKUS)
-// Kompetenzzentrum fuer Satelitenkommunikation (SatCom)
+// Fraunhofer Institute for Open Communication Systems (FOKUS) 
+// Competence Center NETwork research (NET), St. Augustin, GERMANY 
 //     Stefan Bund <g0dil@berlios.de>
 //
 // This program is free software; you can redistribute it and/or modify
@@ -28,13 +28,19 @@
 
 // Custom includes
 #include <boost/utility.hpp>
-#include <boost/date_time/posix_time/posix_time_types.hpp>
+#include <boost/date_time/posix_time/posix_time.hpp>
+#include <boost/scoped_ptr.hpp>
+#include "../Utils/singleton.hh"
 
 //#include "ClockService.mpp"
 ///////////////////////////////hh.p////////////////////////////////////////
 
 namespace senf {
 
+#ifndef DOXYGEN
+    namespace detail { class ClockServiceTest; }
+#endif
+
     // Implementation note:
     //
     // The clock value is represented as a 64bit unsigned integer number of nanosecods elapsed since
@@ -59,24 +65,27 @@ namespace senf {
     // amount the time has been changed. To do this we need an as accurate as possible approximation
     // of the expected current time value. We need to differentiate two cases:
     //
-    // a) Clock skew detected in within now()
+    // a) Clock skew detected within now()
     //
-    // In this case, we use getitimer() to find the time remaining in the timer. Using this value and
-    // an the saved gettimeofday() value we can adjust base_ accordingly.
+    // In this case, we use getitimer() to find the time remaining in the timer. Using this value
+    // and the saved gettimeofday() value we can adjust base_ accordingly.
     //
     // b) Clock skew detected in the signal handler
     //
-    // In this case we use the save gettimeofday() value + CheckInterval to adjust base_.
+    // In this case we use the saved gettimeofday() value + CheckInterval to adjust base_.
     
     /** \brief Reliable high precision monotonous clock source
 
         The ClockService provides a highly accurate monotonous clock source based on
         gettimeofday(). However, it takes additional precautions to detect clock skew.
 
-        \fixme Implement the clock-skew detection
+        \implementation We use a mix of static and non-static members to achieve high performance
+            in the normal case (no clock skew) and still encapsulate the dependency on legacy C
+            headers. Using the senf::singleton mixin ensures, that the instance is constructed
+            before main even when instance() is not called.
       */
     class ClockService
-        : boost::noncopyable
+        : singleton<ClockService>
     {
     public:
         ///////////////////////////////////////////////////////////////////////////
@@ -87,7 +96,7 @@ namespace senf {
             Unsigned integer type representing scheduler time. Scheduler time is measured in
             nanoseconds relative to some implementation defined reference time.
          */
-        typedef boost::uint_fast64_t clock_type;
+        typedef boost::int_fast64_t clock_type;
 
         /** \brief Absolute time data type
 
@@ -95,7 +104,7 @@ namespace senf {
          */
         typedef boost::posix_time::ptime abstime_type;
 
-        static unsigned const CheckInterval = 1;
+        static unsigned const CheckInterval = 10;
 
         ///////////////////////////////////////////////////////////////////////////
         ///\name Structors and default members
@@ -121,16 +130,46 @@ namespace senf {
                                              corresponding clock value.
                                              \see abstime */
 
-    protected:
+        static clock_type nanoseconds(clock_type v);
+        static clock_type microseconds(clock_type v);
+        static clock_type milliseconds(clock_type v);
+        static clock_type seconds(clock_type v);
+        static clock_type minutes(clock_type v);
+        static clock_type hours(clock_type v);
+        static clock_type days(clock_type v);
+
+        static void restart();
 
     private:
         ClockService();
 
-        static ClockService & instance();
-        
+        void timer();
+
+        clock_type now_m();
+        abstime_type abstime_m(clock_type clock);
+        clock_type clock_m(abstime_type time);
+        void restart_m(bool restart = true);
+
+        bool checkSkew(boost::posix_time::ptime time);
+        void updateSkew(boost::posix_time::ptime time);
+        void clockSkew(boost::posix_time::ptime time, boost::posix_time::ptime expected);
+
+        void restartTimer(bool restart = true);
+
         boost::posix_time::ptime base_;
-    };
+        boost::posix_time::ptime heartbeat_;
 
+        // I don't want this header to depend on the legacy C headers.
+        /// Internal: ClockService private data (PIMPL idiom)
+        struct Impl;
+        boost::scoped_ptr<Impl> impl_;
+
+        friend class Impl;
+#ifndef DOXYGEN
+        friend class senf::detail::ClockServiceTest;
+        friend class singleton<ClockService>;
+#endif
+    };
 
 }