NAME

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

SYNOPSIS

         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
         $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 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
         $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() 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 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.