NAME

Log::Handler - Log messages to several outputs.

SYNOPSIS

    use Log::Handler;

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

    $log->add(file => {
        filename => 'file.log',
        mode     => 'append',
        maxlevel => 'debug',
        minlevel => 'warning',
        newline  => 1,
    });

    $log->warning("a warinng here");

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 and create patterns to format the messages.

See the documentation for details.

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.

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 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

This helpful option appends a newline to the message if a newline not exist.

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

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
    %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 $level
    %m   Message
    %%   Procent

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
    %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";
    }

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 => 'file.log' });

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

    $log->add(file => { filename => 'file.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 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

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:

    $log->add(file => {
        filename => 'file.log',
        mode     => 'append',
        newline  => 1,
        maxlevel => 6,
        filter_message => qr/log this/,
        # or
        # filter_message => 'log this',
        # filter_message => '^log only this$',
    });

    $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',
        mode     => 'append',
        newline  => 1,
        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',
        mode     => 'append',
        newline  => 1,
        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();

    $log->add(screen => {
        maxlevel => 'info',
        newline  => 1,
        filter_caller  => qr/^Foo::Bar$/,
        # or
        # filter_caller => '^Foo::Bar$',
    });

    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.

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() informations for 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() informations the count of debug_skip.

HowTo use add()

The method add() excepts 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. As example if you want to add a file-output then take a look into the documentation of Log::Handler::Output::File to see which options are available.

There are different ways to add a new output to the handler. One way is to create the output object yourself and pass it with the handler options to add().

Example:

    use Log::Handler;
    use Log::Handler::Output::File;

    # the handler options - how to handle the output
    my %handler_options = (
        timeformat      => '%Y/%m/%d %H:%M:%S',
        newline         => 1,
        message_layout  => '%T [%L] %S: %m',
        maxlevel        => 'debug',
        minlevel        => 'emergency',
        die_on_errors   => 1,
        debug_trace     => 0,
        debug_mode      => 2,
        debug_skip      => 0,
    );

    # the file options - how to handle the file
    my %file_options = (
        filename        => 'file.log',
        filelock        => 1,
        fileopen        => 1,
        reopen          => 1,
        mode            => 'append',
        autoflush       => 1,
        permissions     => '0660',
        utf8            => 1,
    );

    # create the file object
    my $file = Log::Handler::Output::File->new( \%file_options );

    # create a new handler object
    my $log = Log::Handler->new();

    # now we add the file object to the handler with the handler options
    $log->add( $file => \%handler_options );

But it can be simplier! You can merge all options and pass them to add() in one step, you just need to tell the handler what do you want to add.

    use Log::Handler;

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

    $log->add(

        # what do you want to add - a file output
        file => {

            # handler options
            timeformat      => '%Y/%m/%d %H:%M:%S',
            newline         => 1,
            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
            filename        => 'file.log',
            filelock        => 1,
            fileopen        => 1,
            reopen          => 1,
            mode            => 'append',
            autoflush       => 1,
            permissions     => '0660',
            utf8            => 1,

        }
    );

The options will be splitted internal and you don't need to split it yourself, only if you want to do it yourself.

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

Log level methods

debug()
info()
notice()
warning()
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_error(), is_err()
is_critical(), is_crit()
is_alert()
is_emergency(), is_emerg()

These thirteen 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.

Other level methods

There exists some other level methods.

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

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 informations 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',
        mode          => 'append',
        die_on_errors => 0,
    });

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

    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');

    $log->config(config => {
        file => {
            default => {
                newline       => 1,
                debug_mode    => 2,
                die_on_errors => 0
            },
            error_log => {
                filename      => 'error.log',
                maxlevel      => 'warning',
                minlevel      => 'emerg',
                priority      => 1
            },
            common_log => {
                filename      => 'common.log',
                maxlevel      => 'info',
                minlevel      => 'emerg',
                priority      => 2
            },
        }
    });

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 informations.

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',
        mode            => 'append',
        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\-\.]+

EXAMPLES

Log::Handler::Examples

EXTENSIONS

Send me a mail if you have questions.

PREREQUISITES

Prerequisites for all modules:

    Perl 5.6.1
    Carp
    Data::Dumper
    Devel::Backtrace
    Fcntl
    Params::Validate
    POSIX
    Time::HiRes
    Sys::Hostname
    UNIVERSAL::require

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

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

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

To install Log::Handler, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Log::Handler

CPAN shell

perl -MCPAN -e shell
install Log::Handler

For more information on module installation, please visit the detailed CPAN module installation guide.

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NAME

SYNOPSIS

DESCRIPTION

LOG LEVELS

METHODS

new()

add()

HowTo use add()

Log level methods

is_* methods

Other level methods

output()

flush()

errstr()

config()

set_pattern()

EXAMPLES

EXTENSIONS

PREREQUISITES

EXPORTS

REPORT BUGS

AUTHOR

QUESTIONS

COPYRIGHT

DISCLAIMER OF WARRANTY

Module Install Instructions