FileRotate(3p)

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 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.

I initially aasumed a long runinng process but it seems people are using this module as part of short running CGI programs. So, now we look at the last modified time stamp of the log file and compare it to a previous occurance of a DatePattern, on startup only. If the file stat shows the mtime to be earlier than the previous recurrance then I rotate the log file.

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 therefore 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.

                 IDLW    -1200    International Date Line West
                 NT      -1100    Nome
                 HST     -1000    Hawaii Standard
                 CAT     -1000    Central Alaska
                 AHST    -1000    Alaska-Hawaii Standard
                 AKST    -0900    Alaska Standard
                 YST     -0900    Yukon Standard
                 HDT     -0900    Hawaii Daylight
                 AKDT    -0800    Alaska Daylight
                 YDT     -0800    Yukon Daylight
                 PST     -0800    Pacific Standard
                 PDT     -0700    Pacific Daylight
                 MST     -0700    Mountain Standard
                 MDT     -0600    Mountain Daylight
                 CST     -0600    Central Standard
                 CDT     -0500    Central Daylight
                 EST     -0500    Eastern Standard
                 SAT     -0400    Chile
                 EDT     -0400    Eastern Daylight
                 AST     -0400    Atlantic Standard
                 ADT     -0300    Atlantic Daylight
                 NDT     -0230    Newfoundland Daylight
                 AT      -0200    Azores
                 WAT     -0100    West Africa
                 GMT     +0000    Greenwich Mean
                 UT      +0000    Universal (Coordinated)
                 UTC     +0000    Universal (Coordinated)
                 WET     +0000    Western European
                 WEST    +0000    Alias for Western European
                 CET     +0100    Central European
                 FWT     +0100    French Winter
                 MET     +0100    Middle European
                 MEZ     +0100    Middle European
                 MEWT    +0100    Middle European Winter
                 SWT     +0100    Swedish Winter
                 BST     +0100    British Summer     bst=Brazil standard  -0300
                 GB      +0100    GMT with daylight savings
                 CEST    +0200    Central European Summer
                 EET     +0200    Eastern Europe, USSR Zone 1
                 FST     +0200    French Summer
                 MEST    +0200    Middle European Summer
                 MESZ    +0200    Middle European Summer
                 METDST  +0200    An alias for MEST used by HP-UX
                 SAST    +0200    South African Standard
                 SST     +0200    Swedish Summer       sst=South Sumatra    +0700
                 EEST    +0300    Eastern Europe Summer
                 BT      +0300    Baghdad, USSR Zone 2
                 MSK     +0300    Moscow
                 IT      +0330    Iran
                 ZP4     +0400    USSR Zone 3
                 MSD     +0300    Moscow Daylight
                 ZP5     +0500    USSR Zone 4
                 IST     +0530    Indian Standard
                 ZP6     +0600    USSR Zone 5
                 CCT     +0800    China Coast, USSR Zone 7
                 AWST    +0800    West Australian Standard
                 WST     +0800    West Australian Standard
                 PHT     +0800    Asia Manila
                 JST     +0900    Japan Standard, USSR Zone 8
                 ROK     +0900    Republic of Korea
                 CAST    +0930    Central Australian Standard
                 EAST    +1000    Eastern Australian Standard
                 GST     +1000    Guam Standard, USSR Zone 9  gst=Greenland Std
                 CADT    +1030    Central Australian Daylight
                 EADT    +1100    Eastern Australian Daylight
                 IDLE    +1200    International Date Line East
                 NZST    +1200    New Zealand Standard
                 NZT     +1200    New Zealand
                 NZDT    +1300    New Zealand Daylight

-- 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.

AUTHOR
Mark Pfeiffer, <markpf at mlp-consulting dot com dot au> inspired by Dave Rolsky's, <autarch at urth dot org>, code :-)

Kevin Goess <cpan at goess dot org> suggested multiple writers should be supported. He also conned me into doing the time based stuff. Thanks Kevin! :-)

Thanks also to Dan Waldheim for helping with some of the locking issues in a forked environment.

And thanks to Stephen Gordon for his more portable code on lockfile naming.

Copyright
Copyright 2005-2006, Mark Pfeiffer

This code may be copied only under the terms of the Artistic License, or GPL License which may be found in the Perl 5 source kit.

Use 'perldoc perlartistic' to see the Artistic License. Use 'perldoc perlgpl' to see the GNU General Public License.

Complete documentation for Perl, including FAQ lists, should be found on this system using `man perl' or `perldoc perl'. If you have access to the Internet, point your browser at http://www.perl.org/, the Perl Home Page.