# phpman > man > Log::Log4perl::Util::TimeTracker(3pm)

## NAME
    [Log::Log4perl::Util::TimeTracker](https://www.chedong.com/phpMan.php/perldoc/Log%3A%3ALog4perl%3A%3AUtil%3A%3ATimeTracker/markdown) - Track time elapsed

## SYNOPSIS
      use [Log::Log4perl::Util::TimeTracker](https://www.chedong.com/phpMan.php/perldoc/Log%3A%3ALog4perl%3A%3AUtil%3A%3ATimeTracker/markdown);

      my $timer = [Log::Log4perl::Util::TimeTracker](https://www.chedong.com/phpMan.php/perldoc/Log%3A%3ALog4perl%3A%3AUtil%3A%3ATimeTracker/markdown)->new();

        # equivalent to [Time::HiRes::gettimeofday](https://www.chedong.com/phpMan.php/perldoc/Time%3A%3AHiRes%3A%3Agettimeofday/markdown)(), regardless
        # if [Time::HiRes](https://www.chedong.com/phpMan.php/perldoc/Time%3A%3AHiRes/markdown) is present or not.
      my($seconds, $microseconds) = $timer->gettimeofday();

        # reset internal timer
      $timer->reset();

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

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

## DESCRIPTION
    This utility module helps tracking time elapsed for PatternLayout's date and time placeholders.
    Its accuracy depends on the availability of the [Time::HiRes](https://www.chedong.com/phpMan.php/perldoc/Time%3A%3AHiRes/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Time%3A%3AHiRes/markdown) 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
      $timer->reset();

        # 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

    The internal timer of this module gets its time input from the POSIX time() function, or, if the
    [Time::HiRes](https://www.chedong.com/phpMan.php/perldoc/Time%3A%3AHiRes/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Log%3A%3ALog4perl%3A%3AUtil%3A%3ATimeTracker/markdown)->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
    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.

## LICENSE
    Copyright 2002-2013 by Mike Schilli <<m@perlmeister.com>> and Kevin Goess <<cpan@goess.org>>.

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

## AUTHOR
    Please contribute patches to the project on Github:

        <http://github.com/mschilli/log4perl>

    Send bug reports or requests for enhancements to the authors via our

    MAILING LIST (questions, bug reports, suggestions/patches): <log4perl-devel@lists.sourceforge.net>

    Authors (please contact them via the list above, not directly): Mike Schilli
    <<m@perlmeister.com>>, Kevin Goess <<cpan@goess.org>>

    Contributors (in alphabetical order): Ateeq Altaf, Cory Bennett, Jens Berthold, Jeremy Bopp,
    Hutton Davidson, Chris R. Donnelly, Matisse Enzer, Hugh Esco, Anthony Foiani, James FitzGibbon,
    Carl Franks, Dennis Gregorovic, Andy Grundman, Paul Harrington, Alexander Hartmaier David Hull,
    Robert Jacobson, Jason Kohles, Jeff Macdonald, Markus Peter, Brett Rann, Peter Rabbitson, Erik
    Selberg, Aaron Straup Cope, Lars Thegler, David Viner, Mac Yang.