Provided by: liblog-handler-perl_0.82-1_all bug

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!

       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,
               }
           );

   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.