Plugin to assign an empty event a time stamp from the clock. More...

Inheritance diagram for evgen::GeneratedEventTimestamp:

Public Member Functions
	GeneratedEventTimestamp (fhicl::ParameterSet const &pset)
	Constructor: nothing specific. More...

virtual art::Timestamp	eventTimestamp (art::EventID const &id) override
	Returns the time stamp for the specified event. More...

virtual void	rewind () override
	Resets the status; since this plug in is stateless, this is a no-op. More...

Public Member Functions inherited from art::EmptyEventTimestampPlugin
	EmptyEventTimestampPlugin (fhicl::ParameterSet const &pset)

void	doBeginJob ()

void	doEndJob ()

void	doBeginRun (Run const &r)

Timestamp	doBeginRunTimestamp (RunID const &rid)

void	doBeginSubRun (SubRun const &sr)

Timestamp	doBeginSubRunTimestamp (SubRunID const &srid)

Timestamp	doEventTimestamp (EventID const &e)

void	doRewind ()

virtual	~EmptyEventTimestampPlugin ()=default

Private Attributes
art::TimeValue_t const	fOffsetFromEpoch = 0
	Offset to be added to the chosen clock to get an absolute time. More...

Detailed Description

Plugin to assign an empty event a time stamp from the clock.

See also: art::EmptyEventTimestampPlugin

The plug in returns a time stamp that is taken from the current time on the execution node, in nanoseconds.

The time is currently defined as absolute from the UNIX "epoch" (first day of year 1970), but its absolute precision should not be relied upon.

Also note that the time is not guaranteed to be monotonic, that is, generating two events in sequence, it is not guaranteed that the second one has a time stamp larger than the previous. This may for example happen if the clock relies on a CPU internal counter, on a machine with multiple CPUs (that is probably all of them).

Configuration

None so far.

Definition at line 46 of file GeneratedEventTimestamp_plugin.cc.

Constructor & Destructor Documentation

evgen::GeneratedEventTimestamp::GeneratedEventTimestamp ( fhicl::ParameterSet const & pset )

Constructor: nothing specific.

Definition at line 297 of file GeneratedEventTimestamp_plugin.cc.

   : art::EmptyEventTimestampPlugin(pset)
   , fOffsetFromEpoch(details::ns_clock_t::currentOffsetFromEpoch())
 {
   
   mf::LogInfo("GeneratedEventTimestamp")
     << "Timestamp plugin: timestamp from local clock time in nanoseconds";
   if (fOffsetFromEpoch != 0) {
     MF_LOG_TRACE("GeneratedEventTimestamp")
       << "  Time offset from epoch: " << fOffsetFromEpoch << " ns";
   }
   
 } // evgen::GeneratedEventTimestamp::GeneratedEventTimestamp()

Member Function Documentation

art::Timestamp evgen::GeneratedEventTimestamp::eventTimestamp ( art::EventID const & id )

overridevirtual

Returns the time stamp for the specified event.

Implements art::EmptyEventTimestampPlugin.

Definition at line 314 of file GeneratedEventTimestamp_plugin.cc.

 {
   // obtain from the high resolution clock the current time, from the "epoch",
   // in nanoseconds; if the clock is less precise than the nanosecond,
   // the precision gap is filled with randomness
   details::ns_clock_t get_time;
   
   const long long int now_ns = fOffsetFromEpoch + get_time();
   
   // convert into a timestamp
   art::Timestamp ts(now_ns);
   
   mf::LogTrace("GeneratedEventTimestamp")
     << "Generated time stamp: " << ts.value() << " for event " << id;
   
   return ts;
 } // evgen::GeneratedEventTimestamp::eventTimestamp()