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.

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;

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    = 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.