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");

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",
    },
);

use Log::Handler;

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

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

# and maybe later

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

# 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 control 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 description 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!

skip_message

This is the opposite of option filter_message, but it's only possible to set a simple string or regular expression.

$log->add(file => {
    filename => "file.log",
    maxlevel => 6,
    skip => '^do not log this.+$'
});

category

The parameter category works like filter_caller but is much easier to configure. You can set a comma separated list of modules. As example if you would set the category to

category => "MyApp::User"

then all messages of MyApp::User and the submodules would be logged.

Example:

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

$log->add(
    screen => {
        maxlevel => "info",
        category => "MyApp::User, MyApp::Session"
    }
);

package MyApp;
$log->info(__PACKAGE__);

package MyApp::Products;
$log->info(__PACKAGE__);

package MyApp::User;
$log->info(__PACKAGE__);

package MyApp::Users;
$log->info(__PACKAGE__);

package MyApp::User::Settings;
$log->info(__PACKAGE__);

package MyApp::Session;
$log->info(__PACKAGE__);

package MyApp::Session::Settings;
$log->info(__PACKAGE__);

The messages of MyApp and MyApp::Products would not be logged.

The usage of categories is much faster than to filter by caller.

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;

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 => [
        {
            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    = bar@foo.example
    to      = foo@bar.example
    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,
    }
);

set_default_param()

With this methods it's possible to overwrite the default settings for new outputs.

Normally you would do something like

$log->add(
    file => {
        filename => "debug.log",
        maxlevel => "info",
        timeformat => "%b %d %Y %H:%M:%S",
        message_layout => "[%T] %L %P %t %m (%C)"
    }
);

$log->add(
    file => {
        filename => "error.log",
        maxlevel => "error",
        timeformat => "%b %d %Y %H:%M:%S",
        message_layout => "[%T] %L %P %t %m (%C)"
    }
);

Now you can simplify it with

$log->set_default_param(
    timeformat => "%b %d %Y %H:%M:%S",
    message_layout => "[%T] %L %P %t %m (%C)"
);

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

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

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

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

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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module: (e.g. module:Plugin)
distribution: (e.g. distribution:Dancer auth)
author: (e.g. author:SONGMU Redis)
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NAME

SYNOPSIS

DESCRIPTION

IMPORTANT NOTES

LOG LEVELS

LOG LEVEL METHODS

Level methods

is_* methods

SPECIAL LOG METHODS

METHODS

new()

add()

output()

flush()

errstr()

config()

reload()

validate()

set_pattern()

set_level()

set_default_param()

create_logger()

get_logger()

exists_logger()

EXAMPLES

BENCHMARK

EXTENSIONS

PREREQUISITES

EXPORTS

REPORT BUGS

AUTHOR

QUESTIONS

COPYRIGHT

Module Install Instructions