Provided by: liblog-handler-perl_0.87-1_all 
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!
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.
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.