NAME
    Log::Dispatch::FileRotate - Log to files that archive/rotate themselves

SYNOPSIS
      use Log::Dispatch::FileRotate;

      my $file = Log::Dispatch::FileRotate->new( name      => 'file1',
                                           min_level => 'info',
                                           filename  => 'Somefile.log',
                                           mode      => 'append' ,
                                           size      => 10,
                                           max       => 6,
                                          );
      # or for a time based rotation

      my $file = Log::Dispatch::FileRotate->new( name      => 'file1',
                                           min_level => 'info',
                                           filename  => 'Somefile.log',
                                           mode      => 'append' ,
                                           TZ        => 'AEDT',
                                           DatePattern => 'yyyy-dd-HH',
                                          );

      $file->log( level => 'info', message => "your comment\n" );

DESCRIPTION
    This module provides a simple object for logging to files under the
    Log::Dispatch::* system, and automatically rotating them according to
    different constraints. This is basically a Log::Dispatch::File wrapper
    with additions. To that end the arguments

            name, min_level, filename and  mode

    behave the same as Log::Dispatch::File. So see its man page (perldoc
    Log::Dispatch::File)

    The arguments size and max specify the maximum size (in meg) and maximum
    number of log files created. The size defaults to 10M and the max number
    of files defaults to 1. If DatePattern is not defined then we default to
    working in size mode. That is, use size values for deciding when to
    rotate.

    Once DatePattern is defined FileRotate will move into time mode. Once
    this happens file rotation ignores size constraints and uses the defined
    date pattern constraints.

    If you setup a config file using Log::Log4perl::init_and_watch() or the
    like, you can switch between modes just by commenting out the
    DatePattern line.

    When using DatePattern make sure TZ is defined correctly and that the TZ
    you use is understood by Date::Manip. We use Date::Manip to generate our
    recurrences. Bad TZ equals bad recurrences equals surprises! Read the
    Date::Manip man page for more details on TZ.

    DatePattern will default to a daily rotate if your entered pattern is
    incorrect. You will also get a warning message.

    If you have multiple writers that were started at different times you
    will find each writer will try to rotate the log file at a recurrence
    calculated from its start time. To sync all the writers just use a
    config file and update it after starting your last writer. This will
    cause Log::Dispatch::FileRotate->new() to be called by each of the
    writers close to the same time, and if your recurrences aren't too close
    together all should sync up just nicely.

    We handle multiple writers using flock().

DatePattern
    As I said earlier we use Date::Manip for generating our recurrence
    events. This means we can understand Date::Manip's recurrence patterns
    and the normal log4j DatePatterns. We don't use DatePattern to define
    the extension of the log file though.

    DatePattern can therfore take forms like:

          Date::Manip style
                0:0:0:0:5:30:0       every 5 hours and 30 minutes
                0:0:0:2*12:30:0      every 2 days at 12:30 (each day)
                3*1:0:2:12:0:0       every 3 years on Jan 2 at noon

          DailyRollingFileAppender log4j style
                yyyy-MM              every month
                yyyy-ww              every week
                yyyy-MM-dd           every day
                yyyy-MM-dd-a         every day at noon
                yyyy-MM-dd-HH        every hour
                yyyy-MM-dd-HH-MM     every minute

    To specify multiple recurrences in a single string separate them with a
    semicolon: yyyy-MM-dd; 0:0:0:2*12:30:0

    This says we want to rotate every day AND every 2 days at 12:30. Put in
    as many as you like.

    A complete description of Date::Manip recurrences is beyond us here
    except to quote (from the man page):

               A recur description is a string of the format
               Y:M:W:D:H:MN:S .  Exactly one of the colons may
               optionally be replaced by an asterisk, or an asterisk
               may be prepended to the string.

               Any value "N" to the left of the asterisk refers to
               the "Nth" one.  Any value to the right of the asterisk
               refers to a value as it appears on a calendar/clock.
               Values to the right can be listed a single values,
               ranges (2 numbers separated by a dash "-"), or a comma
               separated list of values or ranges.  In a few cases,
               negative values are appropriate.

               This is best illustrated by example.

                 0:0:2:1:0:0:0        every 2 weeks and 1 day
                 0:0:0:0:5:30:0       every 5 hours and 30 minutes
                 0:0:0:2*12:30:0      every 2 days at 12:30 (each day)
                 3*1:0:2:12:0:0       every 3 years on Jan 2 at noon
                 0:1*0:2:12,14:0:0    2nd of every month at 12:00 and 14:00
                 1:0:0*45:0:0:0       45th day of every year
                 0:1*4:2:0:0:0        4th tuesday (day 2) of every month
                 0:1*-1:2:0:0:0       last tuesday of every month
                 0:1:0*-2:0:0:0       2nd to last day of every month

METHODS
    * new(%p)
        This method takes a hash of parameters. The following options are
        valid:

    -- name ($)
        The name of the object (not the filename!). Required.

    -- size ($)
        The maxium (or close to) size the log file can grow too.

    -- max ($)
        The maxium number of log files to create.

    -- TZ ($)
        The TimeZone time based calculations should be done in. This should
        match Date::Manip's concept of timezones and of course your machines
        timezone. Date::Manip will normally work everything out for you.
        Except in my case where EST means Eastern Standard Time in Australia
        not the US! I had to use AEST or EADT instead. Here is a list of
        Date::Manip's timezones straight from its man page.

               The following timezone names are currently understood (and
               can be used in parsing dates).  These are zones defined in
               RFC 822.

                   Universal:  GMT, UT
                   US zones :  EST, EDT, CST, CDT, MST, MDT, PST, PDT
                   Military :  A to Z (except J)
                   Other    :  +HHMM or -HHMM
                   ISO 8601 :  +HH:MM, +HH, -HH:MM, -HH

               In addition, the following timezone abbreviations are also
               accepted.

                     [ .. snip ... ]

    -- DatePattern ($)
        The DatePattern as defined above.

    -- min_level ($)
        The minimum logging level this object will accept. See the
        Log::Dispatch documentation for more information. Required.

    -- max_level ($)
        The maximum logging level this obejct will accept. See the
        Log::Dispatch documentation for more information. This is not
        required. By default the maximum is the highest possible level
        (which means functionally that the object has no maximum).

    -- filename ($)
        The filename to be opened for writing. This is the base name.
        Rotated log files will be renamed filename.1 thru to filename."max".
        Where max is the paramater defined above.

    -- mode ($)
        The mode the file should be opened with. Valid options are 'write',
        '>', 'append', '>>', or the relevant constants from Fcntl. The
        default is 'write'.

    -- autoflush ($)
        Whether or not the file should be autoflushed. This defaults to
        true.

    -- callbacks( \& or [ \&, \&, ... ] )
        This parameter may be a single subroutine reference or an array
        reference of subroutine references. These callbacks will be called
        in the order they are given and passed a hash containing the
        following keys:

         ( message => $log_message, level => $log_level )

        The callbacks are expected to modify the message and then return a
        single scalar containing that modified message. These callbacks will
        be called when either the "log" or "log_to" methods are called and
        will only be applied to a given message once.

    -- DEBUG ($)
        Turn on lots of warning messages to STDERR about what this module is
        doing if set to 1. Really only useful to me.

    * log_message( message => $ )
        Sends a message to the appropriate output. Generally this shouldn't
        be called directly but should be called through the "log()" method
        (in Log::Dispatch::Output).

    * setDatePattern( $ or [ $, $, ... ] )
        Set a new suite of recurrances for file rotation. You can pass in a
        single string or a reference to an array of strings. Multiple
        recurrences can also be define within a single string by seperating
        them with a semi-colon (;)

        See the discussion above regarding the setDatePattern paramater for
        more details.

TODO
    compression, signal based rotates, proper test suite

    Could possibly use Logfile::Rotate as well/instead.

PRINCIPLE AUTHOR
    Mark Pfeiffer 

