// $Id$
//
-// Copyright (C) 2007
-// Fraunhofer Institut fuer offene Kommunikationssysteme (FOKUS)
-// Kompetenzzentrum fuer Satelitenkommunikation (SatCom)
+// Copyright (C) 2007
+// 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
\brief ClockService inline non-template implementation */
// Custom includes
-#include "boost/date_time/posix_time/posix_time_types.hpp"
+#include <boost/date_time/posix_time/posix_time_types.hpp>
#define prefix_ inline
///////////////////////////////cci.p///////////////////////////////////////
prefix_ senf::ClockService::clock_type senf::ClockService::now()
{
- // We must make sure to call instance() before fetching the current time since the first call to
- // instance() will construct the singleton and initialize heartbeat_. If this happens *after*
- // fetching the current time checkSkew() will detect clock skew since heartbeat_ will be <
- // current time.
- return instance().now_i();
+ return instance().now_m();
}
prefix_ senf::ClockService::abstime_type senf::ClockService::abstime(clock_type clock)
{
-#ifdef BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG
- return instance().base_ + boost::posix_time::nanoseconds(clock);
-#else
- return instance().base_ + boost::posix_time::microseconds((clock+500)/1000);
-#endif
+ return instance().abstime_m(clock);
}
prefix_ senf::ClockService::clock_type senf::ClockService::clock(abstime_type time)
{
- boost::posix_time::time_duration delta (time - instance().base_);
- return clock_type( delta.ticks() )
- * clock_type( 1000000000UL / boost::posix_time::time_duration::ticks_per_second() );
+ return instance().clock_m(time);
}
prefix_ senf::ClockService::clock_type senf::ClockService::nanoseconds(clock_type v)
prefix_ senf::ClockService::clock_type senf::ClockService::microseconds(clock_type v)
{
- return nanoseconds(1000*v);
+ return v * nanoseconds(1000);
}
prefix_ senf::ClockService::clock_type senf::ClockService::milliseconds(clock_type v)
{
- return microseconds(1000*v);
+ return v * microseconds(1000);
}
prefix_ senf::ClockService::clock_type senf::ClockService::seconds(clock_type v)
{
- return milliseconds(1000*v);
+ return v * milliseconds(1000);
}
prefix_ senf::ClockService::clock_type senf::ClockService::minutes(clock_type v)
{
- return seconds(60*v);
+ return v * seconds(60);
}
prefix_ senf::ClockService::clock_type senf::ClockService::hours(clock_type v)
{
- return minutes(60*v);
+ return v * minutes(60);
}
prefix_ senf::ClockService::clock_type senf::ClockService::days(clock_type v)
{
- return hours(24*v);
+ return v * hours(24);
}
prefix_ void senf::ClockService::restart()
{
- instance().restart_i();
+ instance().restart_m();
}
////////////////////////////////////////
// private members
-prefix_ senf::ClockService & senf::ClockService::instance()
+prefix_ senf::ClockService::clock_type senf::ClockService::now_m()
{
- static ClockService instance;
- return instance;
-}
+ // We want to make the normal case (no skew) really fast. This first 'checkSkew' *might*
+ // transiently fail if a SIGALRM is delivered in the midst of the test. updateSkew will
+ // therefore block signals and do the check again to make sure.
+ //
+ // The opposite case (the test returns 'false' even though it should return 'true') is so highly
+ // improbable that it is treated as academic. (it will be catched by the next SIGALRM)
-prefix_ senf::ClockService::clock_type senf::ClockService::now_i()
-{
boost::posix_time::ptime time (boost::posix_time::microsec_clock::universal_time());
if (checkSkew(time))
updateSkew(time);
- return clock(time);
+
+ // 'clock' will pick up the corrected base_ value if needed.
+ return clock_m(time);
+}
+
+prefix_ senf::ClockService::abstime_type senf::ClockService::abstime_m(clock_type clock)
+{
+#ifdef BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG
+ return base_ + boost::posix_time::nanoseconds(clock);
+#else
+ return base_ + boost::posix_time::microseconds((clock+500)/1000);
+#endif
+}
+
+prefix_ senf::ClockService::clock_type senf::ClockService::clock_m(abstime_type time)
+{
+ ///\fixme What happens, if base_ is changed in SIGALRM while reading it here ?
+
+ // Idea: Have *two* base values: one is written by the SIGALRM handler, the other is only
+ // Written by synchronous code. If they differ, we block signals, copy over and continue. If
+ // they transiently differ because we are reading the SIGALRM value while it is being changed
+ // this does not matter: We will then still copy it over.
+
+ boost::posix_time::time_duration delta (time - base_);
+ return clock_type( delta.ticks() )
+ * clock_type( 1000000000UL / boost::posix_time::time_duration::ticks_per_second() );
}
prefix_ bool senf::ClockService::checkSkew(boost::posix_time::ptime time)
{
- return time < heartbeat_ || (time - heartbeat_) > boost::posix_time::seconds(2*CheckInterval);
+ boost::posix_time::ptime h (heartbeat_); // reduce chance for race condition
+ return time < h || (time - h) > boost::posix_time::seconds(2*CheckInterval);
}
prefix_ void senf::ClockService::clockSkew(boost::posix_time::ptime time,