The Perl Toolchain Summit needs more sponsors. If your company depends on Perl, please support this very important event.
 / 
Log-Handler-0.39_16
River stage two • 29 direct dependents • 41 total dependents
9 ++
/ Log::Handler

NAME

Log::Handler - Log messages to one or more 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->alert("foo bar");

DESCRIPTION

This module is just a simple object oriented log handler and very easy to use. It's possible to define a log level for your programs and control the amount of informations that are logged to one or more outputs.

LOG LEVELS

There are eigth levels available:

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

debug is the highest and emergency is the lowest level.

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 timeformat is used for the placeholder %T. You can set timeformat with a date and time format that is converted with POSIX::strftime. The default format is "%b %d %H:%M:%S" and looks like

    Feb 01 12:56:31

As example the format "%Y/%m/%d %H:%M:%S" would looks like

    2007/02/01 12:56:31
dateformat

The same like timeformat. It's 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");

Would log

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

This option is not used on default.

newline

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

    0 - disable (default)
    1 - enable - appends a newline to the log message if not exist
message_layout

With this option you can define 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
    %C   Caller - filename and line number
    %c   Caller - package, filename and line number
    %p   Program name
    %t   Time measurement - replaced with the time since the last call of the handler
    %m   The message.

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().

Placeholders are documented in the section "PLACEHOLDER".

message_pattern

This option is just useful if you want to forward messages with Log::Handler::Output::Forward or insert the message with Log::Handler::Output::DBI or dump messages to the screen with Log::Handler::Output::Screen.

Possible placeholders:

    %L   level
    %T   time
    %D   date
    %P   pid
    %H   hostname
    %N   newline
    %C   caller
    %c   caller
    %p   progname
    %t   mtime
    %m   message

The option expects a array reference with a list of placeholders:

    message_pattern => [ qw/%T %L %H %m/ ]

The patterns are replaced with the pattern names as hash keys and the hash is passed as reference to the output. 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/ ],
        message_layout  => '%m',
        maxlevel        => 'info',
    });

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

    # now you can access it

    sub my_func {
        my $params = shift;
        print "Timestamp: $params->{time}\n";
        print "Level:     $params->{level}\n";
        print "Hostname:  $params->{hostname}\n";
        print "Message:   $params->{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 priority 10 and then 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 die on failed write operations.

    0 - will not die on errors
    1 - will die (e.g. croak) on errors

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

With this option it's possible to define a filter. If the filter is set than 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   => qr/log this/, # log only messages that contain 'log this'
    });

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

If you pass a code reference then you the message is passed as a hash reference as first argument. Example:

    $log->add(file => {
        filename => 'file.log',
        mode     => 'append',
        newline  => 1,
        maxlevel => 6,
        filter   => \&my_filter
    });

    sub my_filter {
        my $m = shift;
        $m->{message} =~ /your filter/;
    }

Also it's possible to define a simple condition with matches. You just have to pass a hash reference with the optione matchN and condition. Example:

    $log->add(file => {
        filename => 'file.log',
        mode     => 'append',
        newline  => 1,
        maxlevel => 6,
        filter   => {
            match1    => 'log this',
            match2    => qr/with that/,
            match3    => '(?:or this|or that)',
            condition => '(match1 && match2) || match3',
        }
    });

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

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

would cause an error.

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    => 'error',
    });

    my $output_object = $log->get_output('error');
debug_trace

You can activate a debugger that writes caller() informations for each log level that would logged. 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 block 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 [WARN] 
       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.

    debug_skip => 2

    Apr 26 12:55:07 [DEBUG] 
       CALL(2): package(main) filename(./trace.pl) line(16) subroutine(main::test2) hasargs(0)
       CALL(1): package(main) filename(./trace.pl) line(14) subroutine(main::test1) hasargs(0)
       CALL(0): package(main) filename(./trace.pl) line(13) subroutine(Log::Handler::__ANON__) hasargs(1)

How to use add()

The method add() excepts 2 option parts; the options for the handler and for the output module you want to use - the output modules got it's own documentation for all options.

There are different ways to add a new output to the handler. The one way is that you 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] %p: %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,
    );

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

    # creating 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.

    # merge the options
    my %all_options = (%output_options, %file_options);

    # pass all options and say what you want to add -> a file!
    $log->add( file => \%all_options );

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

Further examples:

    $log->add( email   => \%all_options );
    $log->add( forward => \%all_options );
    # and so on ...

Take a look to the section "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 the 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 log level would output the message. All methods returns TRUE if the current set of minlevel and maxlevel would log the message and FALSE if not. Example:

    $log->debug(Dumper(\%hash));

This example would dump the hash in any case and pass it to the log handler, but that is not that what we really want!

    if ( $log->is_debug ) {
        $log->debug(Dumper(\%hash));
    }

Now we dump the hash only if the current log level would log it.

The methods is_err(), is_crit() and is_emerg() are just shortcuts.

Other level methods

There exists a lot of other level methods.

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

get_output()

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

errstr()

Call errstr() if you want to get the last error message. This is useful with die_on_errors. If you set die_on_errors to 0 the handler wouldn't croak on failed write operations. Set die_on_errors to control it yourself.

    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;

Or

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

The exception is that the handler croaks 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(filename => 'file.conf');

Or

    $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 default section - I call it section here - can be used to define default parameters for all file outputs.

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', 'name', sub { });

    # or

    $log->set_pattern('%X', 'name', 'value');

Then you can use this pattern in your message layout:

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

EXAMPLES

Log::Handler::Examples

EXTENSIONS

Start it or write me a mail if you have questions.

PREREQUISITES

Prerequisites for all modules:

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

And maybe for the config loader:

    Config::General
    Config::Properties
    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.

TODO

Maybe; don't know

    * Log::Handler::Filter

COPYRIGHT

Copyright (C) 2007 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.

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.