NAME
   Log::Handler - Log messages to several outputs.

SYNOPSIS
       use Log::Handler;

       my $log = Log::Handler->new();

       $log->add(
           file => {
               filename => "file.log",
               maxlevel => "debug",
               minlevel => "warning",
           }
       );

       $log->warning("message");

   Or

       use Log::Handler;

       my $log = Log::Handler->new(
           screen => {
               log_to   => "STDOUT",
               maxlevel => "debug",
               minlevel => "debug",
               message_layout => "%T [%L] %m (%C)",
           },
           screen => {
               log_to   => "STDOUT",
               maxlevel => "info",
               minlevel => "notice",
           },
           screen => {
               log_to   => "STDERR",
               maxlevel => "warning",
               minlevel => "emergency",
           },
       );

   Or

       use Log::Handler;

       my $log = Log::Handler->new();

       $log->config( config => "logger.conf" );

       # and maybe later

       $log->reload( config => "logger.conf" );

   Or

       # create a application wide logger
       package MyApp;
       use Log::Handler;
       my $log = Log::Handler->create_logger("myapp");
       $log->add(screen => { maxlevel => "info" });
       $log->info("info message");

       # get logger with get_logger()
       package MyApp::Admin;
       use Log::Handler;
       my $log = Log::Handler->get_logger("myapp");
       $log->info("info message from MyApp::Admin");

DESCRIPTION
   The `Log::Handler' is a object oriented handler for logging, tracing and
   debugging. It is very easy to use and provides a simple interface for
   multiple output objects with lots of configuration parameters. You can
   easily filter the amount of logged information on a per-output base,
   define priorities, create patterns to format the messages and reload the
   complete logging machine.

   See the documentation for details.

IMPORTANT NOTES
   Note that the default for option `newline' is now set to TRUE and
   newlines will be appended automatically to each message if no newline
   exists.

   A long time I thought about this serious change and have come to the
   decision to change it.

   The default for option `mode' from Log::Handler::Output::File is now
   `append' and not `excl' anymore.

   The methods `reload()' and `validate()' are new since version 0.62. I
   tested it with Screen.pm, File.pm and DBI.pm and it runs fine. If you
   find bugs then open a bug report please :-)

LOG LEVELS
   There are eigth levels available:

       7   debug
       6   info
       5   notice
       4   warning, warn
       3   error, err
       2   critical, crit
       1   alert
       0   emergency, emerg

   `debug' is the highest and `emergency' is the lowest level.

   Level `debug' is the highest level because it basically says to log
   every peep.

LOG LEVEL METHODS
 Level methods
   debug()
   info()
   notice()
   warning(), warn()
   error(), err()
   critical(), crit()
   alert()
   emergency(), emerg()

   The call of a log level method is very simple:

       $log->info("Hello World! How are you?");

   Or maybe:

       $log->info("Hello World!", "How are you?");

   Both calls would log - if level INFO is active:

       Feb 01 12:56:31 [INFO] Hello World! How are you?

 is_* methods
   is_debug()
   is_info()
   is_notice()
   is_warning(), is_warn()
   is_error(), is_err()
   is_critical(), is_crit()
   is_alert()
   is_emergency(), is_emerg()

   These twelve methods could be very useful if you want to kwow if the
   current level would log the message. All methods returns TRUE if the
   current set of `minlevel' and `maxlevel' would log the message and FALSE
   if not.

SPECIAL LOG METHODS
   fatal, is_fatal
   trace
   dump
   die
   log

   For a full list take a look into the documentation of
   Log::Handler::Levels.

METHODS
 new()
   Call `new()' to create a new log handler object.

       my $log = Log::Handler->new();

 add()
   Call `add()' to add a new output object.

   The method expects 2 parts of options; the options for the handler and
   the options for the output module you want to use. The output modules
   got it's own documentation for all options.

   Example:

       use Log::Handler;

       my $log = Log::Handler->new();

       $log->add(

           # Add "file output"
           file => {

               # handler options (see Log::Handler)
               timeformat      => "%Y/%m/%d %H:%M:%S",
               message_layout  => "%T [%L] %S: %m",
               maxlevel        => "debug",
               minlevel        => "emergency",
               die_on_errors   => 1,
               debug_trace     => 0,
               debug_mode      => 2,
               debug_skip      => 0,

               # file options (see Log::Handler::Output::File)
               filename        => "file.log",
               filelock        => 1,
               fileopen        => 1,
               reopen          => 1,
               autoflush       => 1,
               permissions     => "0660",
               utf8            => 1,

           }
       );

   Take a look to Log::Handler::Examples for more examples.

   The following options are possible for the handler:

   maxlevel and minlevel
       With these options it's possible to set the log levels for your
       program.

       Example:

           maxlevel => "error"
           minlevel => "emergency"

           # or

           maxlevel => "err"
           minlevel => "emerg"

           # or

           maxlevel => 3
           minlevel => 0

       It's possible to set the log level as string or as number. The
       default setting for `maxlevel' is `warning' and the default setting
       for `minlevel' is `emergency'.

       Example: If `maxlevel' is set to `warning' and `minlevel' to
       `emergency' then the levels `warning', `error', `critical', `alert'
       and `emergency' would be logged.

       You can set both to 8 or `nothing' if you want to disable the
       logging machine.

   timeformat
       The option `timeformat' is used to set the format for the
       placeholder `%T'. The string is converted with `POSIX::strftime'.
       The default format is set to "%b %d %H:%M:%S" and looks like

           Feb 01 12:56:31

       If you would set the format to "%Y/%m/%d %H:%M:%S" it would looks
       like

           2007/02/01 12:56:31

   dateformat
       This options works like `timeformat'. You can set a format that is
       used for the placeholder `%D'. It's just useful if you want to split
       the date and time:

           $log->add(file => {
               filename       => "file.log",
               dateformat     => "%Y-%m-%d",
               timeformat     => "%H:%M:%S",
               message_layout => "%D %T %L %m",
           });

           $log->error("an error here");

       This looks like

           2007-02-01 12:56:31 ERROR an error here

       This option is not used by default.

   newline
       `newline' is a very helpful option. It let the logger appends a
       newline to the message if a newline doesn't exist.

           0 - do nothing
           1 - append a newline if not exist (default)

       Example:

           $log->add(
               screen => {
                   newline  => 1,
                   maxlevel => "info",
               }
           );

           $log->info("message\n");
           $log->info("message");

       In both cases the message would be logged with a newline at the end.

   message_layout
       With this option it's possible to create your own message layout
       with different placeholders in `printf()' style. The available
       placeholders are:

           %L   Log level
           %T   Time or full timestamp (option timeformat)
           %D   Date (option dateformat)
           %P   PID
           %H   Hostname
           %U   User name
           %G   Group name
           %N   Newline
           %S   Program name
           %C   Caller - filename and line number
           %p   Caller - package name
           %f   Caller - file name
           %l   Caller - line number
           %s   Caller - subroutine name
           %r   Runtime in seconds since program start
           %t   Time measurement - replaced with the time since the last call of $log->$level
           %m   Message
           %%   Percent

       The default message layout is set to "%T [%L] %m".

       As example the following code

           $log->alert("foo bar");

       would log

           Feb 01 12:56:31 [ALERT] foo bar

       If you set `message_layout' to

           message_layout => "%T foo %L bar %m (%C)"

       and call

           $log->info("baz");

       then it would log

           Feb 01 12:56:31 foo INFO bar baz (script.pl, line 40)

       Traces will be appended after the complete message.

       You can create your own placeholders with the method
       `set_pattern()'.

   message_pattern
       This option is just useful if you want to forward messages to output
       modules that needs the parts of a message as a hash reference - as
       example Log::Handler::Output::Forward, Log::Handler::Output::DBI or
       Log::Handler::Output::Screen.

       The option expects a list of placeholders:

           # as a array reference
           message_pattern => [ qw/%T %L %H %m/ ]

           # or as a string
           message_pattern => "%T %L %H %m"

       The patterns will be replaced with real names as hash keys.

           %L   level
           %T   time
           %D   date
           %P   pid
           %H   hostname
           %U   user
           %G   group
           %N   newline
           %r   runtime
           %C   caller
           %p   package
           %f   filename
           %l   line
           %s   subroutine
           %S   progname
           %t   mtime
           %m   message

       Here a full code example:

           use Log::Handler;

           my $log = Log::Handler->new();

           $log->add(forward => {
               forward_to      => \&my_func,
               message_pattern => [ qw/%T %L %H %m/ ],
               message_layout  => "%m",
               maxlevel        => "info",
           });

           $log->info("a forwarded message");

           # now you can access it

           sub my_func {
               my $msg = shift;
               print "Timestamp: $msg->{time}\n";
               print "Level:     $msg->{level}\n";
               print "Hostname:  $msg->{hostname}\n";
               print "Message:   $msg->{message}\n";
           }

   prepare_message
       `prepare_message' is useful if you want to do something with the
       message before it will be logged... maybe you want to create your
       own layout because message_layout doesn't meet your claim.

           $log->add(
               screen => {
                   newline => 1,
                   message_layout  => "%m (%t)",
                   message_pattern => [ qw/%T %L %H %m/ ],
                   prepare_message => \&format,
               }
           );

           $log->error("foo");
           $log->error("bar");
           $log->error("baz");

           sub format {
               my $m = shift;

               $m->{message} = sprintf("%-20s %-20s %-20s %s",
                   $m->{time}, $m->{level}, $m->{hostname}, $m->{message});
           }

       The output looks like

           Mar 08 15:14:20      ERROR                h1434036             foo (0.039694)
           Mar 08 15:14:20      ERROR                h1434036             bar (0.000510)
           Mar 08 15:14:20      ERROR                h1434036             baz (0.000274)

   priority
       With this option you can set the priority of your output objects.
       This means that messages will be logged at first to the outputs with
       a higher priority. If this option is not set then the default
       priority begins with 10 and will be increased +1 with each output.
       Example:

       We add a output with no priority

           $log->add(file => { filename => "file1.log" });

       This output gets the priority of 10. Now we add another output

           $log->add(file => { filename => "file2.log" });

       This output gets the priority of 11... and so on.

       Messages would be logged at first to the output with the priority of
       10 and then to the output with the priority of 11. Now you can add
       another output and set the priority to 1.

           $log->add(screen => { dump => 1, priority => 1 });

       Messages would be logged now at first to the screen.

   die_on_errors
       Set `die_on_errors' to 0 if you don't want that the handler dies on
       failed write operations.

           0 - to disable it
           1 - to enable it

       If you set `die_on_errors' to 0 then you have to controll it
       yourself.

           $log->info("info message") or die $log->errstr();

           # or Log::Handler->errstr()
           # or Log::Handler::errstr()
           # or $Log::Handler::ERRSTR

   remove_on_reload
       This option is set to 1 by default.

       Take a look to the decription of the method `reload' for more
       information about this option.

   filter_message
       With this option it's possible to set a filter. If the filter is set
       then only messages will be logged that match the filter. You can
       pass a regexp, a code reference or a simple string. Example:

           $log->add(file => {
               filename => "file.log",
               maxlevel => 6,
               filter_message => qr/log this/,
               # or
               # filter_message => "log this",
               # filter_message => '^log only this$',
           });

           $log->info("log this");
           $log->info("but not that");

       If you pass your own code then you have to check the message
       yourself.

           $log->add(file => {
               filename => "file.log",
               maxlevel => 6,
               filter_message => \&my_filter
           });

           # return TRUE if you want to log the message, FALSE if not
           sub my_filter {
               my $msg = shift;
               $msg->{message} =~ /your filter/;
           }

       It's also possible to define a simple condition with matches. Just
       pass a hash reference with the options `matchN' and `condition'.
       Example:

           $log->add(file => {
               filename => "file.log",
               maxlevel => 6,
               filter_message => {
                   match1    => "log this",
                   match2    => qr/with that/,
                   match3    => "(?:or this|or that)",
                   condition => "(match1 && match2) || match3",
               }
           });

       NOTE that re-eval in regexes is not valid! Something like

           match1 => '(?{unlink("file.txt")})'

       would cause an error!

   filter_caller
       You can use this option to set a package name. Only messages from
       this packages will be logged.

       Example:

           my $log = Log::Handler->new();

           $log->add(screen => {
               maxlevel => "info",
               filter_caller  => qr/^Foo::Bar\z/,
               # or
               # filter_caller => "^Foo::Bar\z",
           });

           package Foo::Bar;
           $log->info("log this");

           package Foo::Baz;
           $log->info("but not that");

           1;

       This would only log the message from the package `Foo::Bar'.

   except_caller
       This option is just the opposite of `filter_caller'.

       If you want to log messages from all callers but `Foo::Bar':

           except_caller => qr/^Foo::Bar\z/

   alias
       You can set an alias if you want to get the output object later.
       Example:

           my $log = Log::Handler->new();

           $log->add(screen => {
               maxlevel => 7,
               alias    => "screen-out",
           });

           my $screen = $log->output("screen-out");

           $screen->log(message => "foo");

           # or in one step

           $log->output("screen-out")->log(message => "foo");

   debug_trace
       You can activate a debugger that writes `caller()' information about
       each active log level. The debugger is logging all defined values
       except `hints' and `bitmask'. Set `debug_trace' to 1 to activate the
       debugger. The debugger is set to 0 by default.

   debug_mode
       There are two debug modes: line(1) and block(2) mode. The default
       mode is 1.

       The line mode looks like this:

           use strict;
           use warnings;
           use Log::Handler;

           my $log = Log::Handler->new()

           $log->add(file => {
               filename    => "*STDOUT",
               maxlevel    => "debug",
               debug_trace => 1,
               debug_mode  => 1
           });

           sub test1 { $log->warning() }
           sub test2 { &test1; }

           &test2;

       Output:

           Apr 26 12:54:11 [WARNING]
              CALL(4): package(main) filename(./trace.pl) line(15) subroutine(main::test2) hasargs(0)
              CALL(3): package(main) filename(./trace.pl) line(13) subroutine(main::test1) hasargs(0)
              CALL(2): package(main) filename(./trace.pl) line(12) subroutine(Log::Handler::__ANON__) hasargs(1)
              CALL(1): package(Log::Handler) filename(/usr/local/share/perl/5.8.8/Log/Handler.pm) line(713) subroutine(Log::Handler::_write) hasargs(1)
              CALL(0): package(Log::Handler) filename(/usr/local/share/perl/5.8.8/Log/Handler.pm) line(1022) subroutine(Devel::Backtrace::new) hasargs(1) wantarray(0)

       The same code example but the debugger in block mode would looks
       like this:

              debug_mode => 2

       Output:

          Apr 26 12:52:17 [DEBUG]
             CALL(4):
                package     main
                filename    ./trace.pl
                line        15
                subroutine  main::test2
                hasargs     0
             CALL(3):
                package     main
                filename    ./trace.pl
                line        13
                subroutine  main::test1
                hasargs     0
             CALL(2):
                package     main
                filename    ./trace.pl
                line        12
                subroutine  Log::Handler::__ANON__
                hasargs     1
             CALL(1):
                package     Log::Handler
                filename    /usr/local/share/perl/5.8.8/Log/Handler.pm
                line        681
                subroutine  Log::Handler::_write
                hasargs     1
             CALL(0):
                package     Log::Handler
                filename    /usr/local/share/perl/5.8.8/Log/Handler.pm
                line        990
                subroutine  Devel::Backtrace::new
                hasargs     1
                wantarray   0

   debug_skip
       This option let skip the `caller()' information the count of
       `debug_skip'.

 output()
   Call `output($alias)' to get the output object that you added with the
   option `alias'.

   It's possible to access a output directly:

       $log->output($alias)->log(message => "booo");

   For more information take a look to the option `alias'.

 flush()
   Call `flush()' if you want to send flush to all outputs that can flush.

   Flush means to flush buffers and/or close and re-open outputs.

   If you want to send it only to some outputs you can pass the aliases.

       $log->flush(); # flush all
       $log->flush("foo", "bar"); # flush only foo and bar

   If option "die_on_errors" is set to 0 then you can intercept errors
   with:

       $log->flush or die $log->errstr;

 errstr()
   Call `errstr()' if you want to get the last error message. This is
   useful if you set `die_on_errors' to `0' and the handler wouldn't die on
   failed write operations.

       use Log::Handler;

       my $log = Log::Handler->new();

       $log->add(file => {
           filename      => "file.log",
           maxlevel      => "info",
           die_on_errors => 0,
       });

       $log->info("Hello World!") or die $log->errstr;

   Or

       unless ( $log->info("Hello World!") ) {
           $error_string = $log->errstr;
           # do something with $error_string
       }

   The exception is that the handler dies in any case if the call of
   `new()' or `add()' fails because on missing or wrong settings!

 config()
   With this method it's possible to load your output configuration from a
   file.

       $log->config(config => "file.conf");

   Or

       $log->config(config => {
           file => [
               {
                   alias    => "error_log",
                   filename => "error.log",
                   maxlevel => "warning",
                   minlevel => "emerg",
                   priority => 1
               },
               {
                   alias    => "common_log",
                   filename => "common.log",
                   maxlevel => "info",
                   minlevel => "emerg",
                   priority => 2
               },
           ],
           screen => {
               alias    => "screen",
               maxlevel => "debug",
               minlevel => "emerg",
               log_to   => "STDERR",
           },
       });

   The key "default" is used here to define default parameters for all file
   outputs. All other keys (`error_log', `common_log') are used as aliases.

   Take a look into the documentation of Log::Handler::Config for more
   information.

 reload()
   With the method `reload()' it's possible to reload the logging machine.
   Just pass the complete new configuration for all outputs, it works
   exaclty like `config()'.

   At first you should know that it's highly recommended to set a alias for
   each output. If you don't set a alias then the logger doesn't know which
   output-objects to reload. If a output-objects doesn't have a alias then
   the objects will be removed and the new configuration will be added.

   Example:

   logger.conf

       <file>
           alias    = debug
           filename = debug.log
           maxlevel = debug
           minlevel = emerg
       </file>

       <file>
           alias    = common
           filename = common.log
           maxlevel = info
           minlevel = emerg
       </file>

   Load the configuration

       $log->config(config => "logger.conf");

   Now change the configuration in logger.conf

       <file>
           alias    = common
           filename = common.log
           maxlevel = notice
           minlevel = emerg
       </file>

       <sendmail>
           alias   = sendmail
           from    = [email protected]
           to      = [email protected]
           subject = your subject
       </sendmail>

   What happends now...

   The file-output with the alias `debug' will be removed, the file-output
   with the alias `common' will be reloaded and the output with the alias
   `sendmail' will be added.

   If you don't want that output-objects will be removed because they were
   added internal, then you can set the option `remove_on_reload' to 0.

   Example:

       $log->config(config => "logger.conf");

       $log->add(
           forward => {
               forward_to => \&my_func,
               remove_on_reload => 0,
           }
       );

   The forward-output is not removed after a reload.

 validate()
   The method `validate()' expects the same arguments like `config()' and
   `reload()'.

   Maybe you want to validate your options before you pass them to
   `config()' or `reload()'.

   Example:

       my $log = Log::Handler->new();

       $log->config( config => \%config );

       # and maybe later

       if ( $log->validate( config => \%new_config ) ) {
           $log->reload( config => \%new_config );
       } else {
           warn "unable to reload configuration";
           warn $log->errstr;
       }

 set_pattern()
   With this option you can set your own placeholders. Example:

       $log->set_pattern("%X", "key_name", sub { "value" });

       # or

       $log->set_pattern("%X", "key_name", "value");

   Then you can use this pattern in your message layout:

       $log->add(file => {
           filename        => "file.log",
           message_layout  => "%X %m%N",
       });

   Or use it with `message_pattern':

       sub func {
           my $m = shift;
           print "$m->{key_name} $m->{message}\n";
       }

       $log->add(forward => {
           forward_to      => \&func,
           message_pattern => "%X %m",
       });

   Note: valid character for the key name are: `[%\w\-\.]+'

 set_level()
   With this method it's possible to change the log level at runtime.

   To change the log level it's necessary to use a alias - see option
   `alias'.

       $log->set_level(
           $alias => { # option alias
               minlevel => $new_minlevel,
               maxlevel => $new_maxlevel,
           }
       );

 create_logger()
   `create_logger()' is the same like `new()' but it creates a global
   logger.

       my $log = Log::Handler->create_logger("myapp");

 get_logger()
   With `get_logger()' it's possible to get a logger that was created with
   `create_logger()' or with

       use Log::Handler "myapp";

   Just call

       my $log = Log::Handler->get_logger("myapp");

   If the logger does not exists then a new logger will be created and
   returned.

 exists_logger()
   With `exists_logger()' it's possible to check if a logger exists and it
   returns TRUE or FALSE.

EXAMPLES
   Log::Handler::Examples

BENCHMARK
   The benchmark (examples/benchmark/benchmark.pl) runs on a Intel Core
   i7-920 with the following result:

       simple pattern output took     :  1 wallclock secs ( 1.26 usr +  0.01 sys =  1.27 CPU) @ 78740.16/s (n=100000)
       default pattern output took    :  2 wallclock secs ( 2.08 usr +  0.15 sys =  2.23 CPU) @ 44843.05/s (n=100000)
       complex pattern output took    :  4 wallclock secs ( 3.22 usr +  0.23 sys =  3.45 CPU) @ 28985.51/s (n=100000)
       message pattern output took    :  3 wallclock secs ( 2.72 usr +  0.16 sys =  2.88 CPU) @ 34722.22/s (n=100000)
       suppressed output took         :  0 wallclock secs ( 0.08 usr +  0.00 sys =  0.08 CPU) @ 1250000.00/s (n=100000)
       filtered caller output took    :  2 wallclock secs ( 2.10 usr +  0.68 sys =  2.78 CPU) @ 35971.22/s (n=100000)
       suppressed caller output took  :  1 wallclock secs ( 0.54 usr +  0.00 sys =  0.54 CPU) @ 185185.19/s (n=100000)
       filtered messages output took  :  3 wallclock secs ( 2.62 usr +  0.08 sys =  2.70 CPU) @ 37037.04/s (n=100000)

EXTENSIONS
   Send me a mail if you have questions.

PREREQUISITES
   Prerequisites for all modules:

       Carp
       Data::Dumper
       Fcntl
       Params::Validate
       POSIX
       Time::HiRes
       Sys::Hostname
       UNIVERSAL

   Recommended modules:

       Config::General
       Config::Properties
       DBI
       IO::Socket
       Net::SMTP
       YAML

   Just for the test suite:

       File::Spec
       Test::More

EXPORTS
   No exports.

REPORT BUGS
   Please report all bugs to <jschulz.cpan(at)bloonix.de>.

AUTHOR
   Jonny Schulz <jschulz.cpan(at)bloonix.de>.

QUESTIONS
   Do you have any questions or ideas?

   MAIL: <jschulz.cpan(at)bloonix.de>

   IRC: irc.perl.org#perl

   If you send me a mail then add Log::Handler into the subject.

COPYRIGHT
   Copyright (C) 2007-2009 by Jonny Schulz. All rights reserved.

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

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