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Michael Schilli > Log-Log4perl-1.38 > Log::Log4perl::Util::TimeTracker



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Log::Log4perl::Util::TimeTracker - Track time elapsed


  use Log::Log4perl::Util::TimeTracker;

  my $timer = Log::Log4perl::Util::TimeTracker->new();

    # equivalent to Time::HiRes::gettimeofday(), regardless
    # if Time::HiRes is present or not. 
  my($seconds, $microseconds) = $timer->gettimeofday();

    # reset internal timer

    # return milliseconds since last reset
  $msecs = $timer->milliseconds();

    # return milliseconds since last call
  $msecs = $timer->delta_milliseconds();


This utility module helps tracking time elapsed for PatternLayout's date and time placeholders. Its accuracy depends on the availability of the Time::HiRes module. If it's available, its granularity is milliseconds, if not, seconds.

The most common use of this module is calling the gettimeofday() method:

  my($seconds, $microseconds) = $timer->gettimeofday();

It returns seconds and microseconds of the current epoch time. If Time::HiRes is installed, it will simply defer to its gettimeofday() function, if it's missing, time() will be called instead and $microseconds will always be 0.

To measure time elapsed in milliseconds, use the reset() method to reset the timer to the current time, followed by one or more calls to the milliseconds() method:

    # reset internal timer

    # return milliseconds since last reset
  $msecs = $timer->milliseconds();

On top of the time span between the last reset and the current time, the module keeps track of the time between calls to delta_milliseconds():

  $msecs = $timer->delta_milliseconds();

On the first call, this will return the number of milliseconds since the last reset(), on subsequent calls, it will return the time elapsed in milliseconds since the last call to delta_milliseconds() instead. Note that reset() also resets the time of the last call.

The internal timer of this module gets its time input from the POSIX time() function, or, if the Time::HiRes module is available, from its gettimeofday() function. To figure out which one it is, use

    if( $timer->hires_available() ) {
        print "Hooray, we get real milliseconds!\n";
    } else {
        print "Milliseconds are just bogus\n";

For testing purposes, a different time source can be provided, so test suites can simulate time passing by without actually having to wait:

  my $start_time = time();

  my $timer = Log::Log4perl::Util::TimeTracker->new(
          time_function => sub {
              return $start_time++;

Every call to $timer->epoch() will then return a time value that is one second ahead of the the value returned on the previous call. This also means that every call to delta_milliseconds() will return a value that exceeds the value returned on the previous call by 1000.


Copyright 2002-2009 by Mike Schilli <> and Kevin Goess <>.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

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