NAME
Log::Handler - Log messages to one or more outputs.
SYNOPSIS
use Log::Handler;
my $log = Log::Handler->new();
$log->add(file => {
filename => 'file.log',
mode => 'append',
maxlevel => 'debug',
minlevel => 'warning',
newline => 1,
});
$log->warning("a warinng here");
DESCRIPTION
This module is just a simple object oriented log handler and very easy
to use. It's possible to define a log level for your programs and
control the amount of informations that are logged to one or more
outputs.
LOG LEVELS
There are eigth levels available:
7 debug
6 info
5 notice
4 warning
3 error, err
2 critical, crit
1 alert
0 emergency, emerg
"debug" is the highest and "emergency" is the lowest level.
METHODS
new()
Call "new()" to create a new log handler object.
my $log = Log::Handler->new();
add()
Call "add()" to add a new output object.
The following options are possible for the handler:
maxlevel and minlevel
With these options it's possible to set the log levels for your
program.
Example:
maxlevel => 'error'
minlevel => 'emergency'
# or
maxlevel => 'err'
minlevel => 'emerg'
# or
maxlevel => 3
minlevel => 0
It's possible to set the log level as string or as number. The
default setting for "maxlevel" is "warning" and the default setting
for "minlevel" is "emergency".
Example: If "maxlevel" is set to "warning" and "minlevel" to
"emergency" then the levels "warning", "error", "critical", "alert"
and "emergency" would be logged.
You can set both to 8 or "nothing" if you want to disable the
logging machine.
timeformat
The option "timeformat" is used for the placeholder %T. You can set
"timeformat" with a date and time format that is converted with
"POSIX::strftime". The default format is "%b %d %H:%M:%S" and looks
like
Feb 01 12:56:31
As example the format "%Y/%m/%d %H:%M:%S" would looks like
2007/02/01 12:56:31
dateformat
This options works like "timeformat". It's useful if you want to
split the date and time:
$log->add(file => {
filename => 'file.log',
dateformat => '%Y-%m-%d',
timeformat => '%H:%M:%S',
message_layout => '%D %T %L %m',
});
$log->error("an error here");
Would log
2007-02-01 12:56:31 ERROR an error here
This option is not used by default.
newline
This helpful option appends a newline to the output message if a
newline not exist.
0 - to disable it (default)
1 - to enable it
message_layout
With this option you can define your own message layout with
different placeholders in "printf()" style. The available
placeholders are:
%L Log level
%T Time or full timestamp (option timeformat)
%D Date (option dateformat)
%P PID
%H Hostname
%N Newline
%S Program name
%R Runtime in seconds since program start
%C Caller - filename and line number
%p Caller - package name
%f Caller - file name
%l Caller - line number
%s Caller - subroutine name
%t Time measurement - replaced with the time since the last call of the handler
%m Message
%% Procent
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
%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";
}
priority
With this option you can set the priority of your output objects.
This means that messages will be logged at first to the outputs with
a higher priority. If this option is not set then the default
priority begins with 10 and will be increased +1 with each output.
Example:
We add a output with no priority
$log->add(file => { filename => 'file.log' });
This output gets the priority of 10. Now we add another output
$log->add(file => { filename => 'file.log' });
This output gets the priority of 11... and so on.
Messages would be logged at first to the output with the priority of
10 and 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
filter
With this option it's possible to set a filter for the outputs. 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',
mode => 'append',
newline => 1,
maxlevel => 6,
filter => qr/log this/, # log only messages that contain 'log this'
});
$log->info('log this');
$log->info('but not that');
If you pass your own code then you have to check the message
yourself.
$log->add(file => {
filename => 'file.log',
mode => 'append',
newline => 1,
maxlevel => 6,
filter => \&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',
mode => 'append',
newline => 1,
maxlevel => 6,
filter => {
match1 => 'log this',
match2 => qr/with that/,
match3 => '(?:or this|or that)',
condition => '(match1 && match2) || match3',
}
});
NOTE that re-eval in regexes is not valid! Something like
match1 => '(?{unlink("file.txt")})'
would cause an error!
alias
You can set an alias if you want to get the output object later.
Example:
my $log = Log::Handler->new();
$log->add(screen => {
maxlevel => 7,
alias => 'screen-out',
});
my $screen = $log->output('screen-out');
$screen->log('foo');
# or in one step
$log->output('screen-out')->log(message => 'foo');
debug_trace
You can activate a debugger that writes "caller()" informations for
each log level that would logged. The debugger is logging all
defined values except "hints" and "bitmask". Set "debug_trace" to 1
to activate the debugger. The debugger is set to 0 by default.
debug_mode
There are two debug modes: line(1) and block(2) mode. The default
mode is 1.
The 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
Another way to enable the debugger very shortly is ...
{
local $Log::Handler::TRACE = 1;
$log->info('backtrace');
}
debug_skip
This option let skip the "caller()" informations the count of
"debug_skip".
debug_skip => 2
Apr 26 12:55:07 [DEBUG]
CALL(2): package(main) filename(./trace.pl) line(16) subroutine(main::test2) hasargs(0)
CALL(1): package(main) filename(./trace.pl) line(14) subroutine(main::test1) hasargs(0)
CALL(0): package(main) filename(./trace.pl) line(13) subroutine(Log::Handler::__ANON__) hasargs(1)
HowTo use add()
The method "add()" excepts 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. As example if
you want to add a file-output then take a look into the documentation of
Log::Handler::Output::File.
There are different ways to add a new output to the handler. The one way
is to create the output object yourself and pass it with the handler
options to "add()".
Example:
use Log::Handler;
use Log::Handler::Output::File;
# the handler options - how to handle the output
my %handler_options = (
timeformat => '%Y/%m/%d %H:%M:%S',
newline => 1,
message_layout => '%T [%L] %S: %m',
maxlevel => 'debug',
minlevel => 'emergency',
die_on_errors => 1,
debug_trace => 0,
debug_mode => 2,
debug_skip => 0,
);
# the file options - how to handle the file
my %file_options = (
filename => 'file.log',
filelock => 1,
fileopen => 1,
reopen => 1,
mode => 'append',
autoflush => 1,
permissions => '0660',
utf8 => 1,
);
# create the file object
my $file = Log::Handler::Output::File->new( \%file_options );
# create a new handler object
my $log = Log::Handler->new();
# now we add the file object to the handler with the handler options
$log->add( $file => \%handler_options );
But it can be simplier! You can merge all options and pass them to
"add()" in one step, you just need to tell the handler what do you want
to add.
use Log::Handler;
my $log = Log::Handler->new();
$log->add(
file => { # what do you want to add
# handler options
timeformat => '%Y/%m/%d %H:%M:%S',
newline => 1,
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
filename => 'file.log',
filelock => 1,
fileopen => 1,
reopen => 1,
mode => 'append',
autoflush => 1,
permissions => '0660',
utf8 => 1,
}
);
The options will be splitted intern and you don't need to split it
yourself, only if you want to do it yourself.
Take a look to Log::Handler::Examples for more informations.
Log level methods
debug()
info()
notice()
warning()
error(), err()
critical(), crit()
alert()
emergency(), emerg()
The call of a log level method is very simple:
$log->info("Hello World! How are you?");
Or maybe:
$log->info("Hello World!", "How are you?");
Both calls would log - if the level INFO is active:
Feb 01 12:56:31 [INFO] Hello World! How are you?
is_* methods
is_debug()
is_info()
is_notice()
is_warning()
is_error(), is_err()
is_critical(), is_crit()
is_alert()
is_emergency(), is_emerg()
These thirteen methods could be very useful if you want to kwow if the
current 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.
The following example would dump the hash in any case and pass it to the
log handler:
$log->debug(Dumper(\%hash));
But that is not that what we really want! We want to dump the hash only
if the current log level would log it.
if ( $log->is_debug ) {
$log->debug(Dumper(\%hash));
}
The methods "is_err()", "is_crit()" and "is_emerg()" are just shortcuts.
Other level methods
There exists a lot of other level methods.
For a full list take a look into the documentation of
Log::Handler::Levels.
output()
Call "output($alias)" to get the output object that you added with the
option "alias".
For more informations take a look to the option "alias".
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',
mode => 'append',
die_on_errors => 0,
});
$log->info("Hello World!") or die $log->errstr;
Or
unless ( $log->info("Hello World!") ) {
$error_string = $log->errstr;
# do something with $error_string
}
The exception is that the handler 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(filename => 'file.conf');
Or
$log->config(config => {
file => {
default => {
newline => 1,
debug_mode => 2,
die_on_errors => 0
},
error_log => {
filename => 'error.log',
maxlevel => 'warning',
minlevel => 'emerg',
priority => 1
},
common_log => {
filename => 'common.log',
maxlevel => 'info',
minlevel => 'emerg',
priority => 2
},
}
});
The key "default" can be used 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
informations.
set_pattern()
With this option you can set your own placeholders. Example:
$log->set_pattern('%X', 'name', sub { 'value' });
# or
$log->set_pattern('%X', 'name', 'value');
Then you can use this pattern in your message layout:
$log->add(file => {
filename => 'file.log',
mode => 'append',
message_layout => '%X %m %N',
});
Or use it with "message_pattern":
sub func {
my $m = shift;
print "$m->{name} $m->{message}\n";
}
$log->add(forward => {
forward_to => \&func,
message_pattern => '%X %m',
});
EXAMPLES
Log::Handler::Examples
EXTENSIONS
Send me a mail if you have questions.
PREREQUISITES
Prerequisites for all modules:
Carp
Data::Dumper
Devel::Backtrace
Fcntl
Params::Validate
POSIX
Time::HiRes
Sys::Hostname
UNIVERSAL::require
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 by Jonny Schulz. All rights reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
DISCLAIMER OF WARRANTY
BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
NECESSARY SERVICING, REPAIR, OR CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE
TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.