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Log::Handler::Simple.3pm
Langue: en
Version: 2008-11-27 (ubuntu - 08/07/09)
Section: 3 (Bibliothèques de fonctions)
Sommaire
NAME
Log::Handler::Simple - A simple handler to log messages to a log file.SYNOPSIS
use Log::Handler;
# if you pass any options to new() then a
# Log::Handler::Simple object is created
my $log = Log::Handler->new(filename => '*STDOUT');
# is the same like
my $log = Log::Handler::Simple->new(filename => '*STDOUT');
$log->alert("foo bar");
DESCRIPTION
Maybe you are wondering why this module exists besides "Log::Handler::Output::File".This module is just for backward compatibilities to the old "Log::Handler" - version 0.38. If you install the current version of "Log::Handler" you don't need to rewrite your programs. You can use the old style if you wish.
METHODS
new()
Call "new()" to create a new log handler object.The "new()" method expected the options for the log file. Each option will be set to a default value if not set.
Log levels
There are eigth log levels and thirteen methods to handle this levels:- debug()
- info()
- notice(), note()
- warning(), warn()
- error(), err()
- critical(), crit()
- alert()
- emergency(), emerg()
"debug()" is the highest and "emergency()" or "emerg()" is the lowest log level. You can define the log level with the options "maxlevel" and "minlevel".
The methods "note()", "warn()", "err()", "crit()" and "emerg()" are just shortcuts.
Example:
If you set the option "maxlevel" to "warning" and "minlevel" to "emergency" then the levels emergency, alert, critical, error and warning will be logged.
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 write to the log file (provided that the log level INFO would log)
Feb 01 12:56:31 [INFO] Hello World! How are you?
is_* methods
- is_debug()
- is_info()
- is_notice(), is_note()
- is_warning(), is_warn()
- 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 log level would write the message to the log file. All methods returns TRUE if the handler would log it and FALSE if not. Example:
$log->debug(Dumper(\%hash));
This example would dump the hash in any case and handoff it to the log handler, but this isn't that what we really want because it could costs a lot of resources.
$log->debug(Dumper(\%hash))
if $log->is_debug();
Now we dump the hash only if the current log level would log it.
The methods "is_note()", "is_warn()", "is_err()", "is_crit()" and "is_emerg()" are just shortcuts.
set_prefix()
Call "set_prefix()" to modifier the option prefix after you called "new()".
my $log = Log::Handler::Simple->new(
filename => 'file.log',
mode => 'append',
prefix => "myhost:$$ [<--LEVEL-->] "
);
$log->set_prefix("[<--LEVEL-->] myhost:$$ ");
get_prefix()
Call "get_prefix()" to get the current prefix if you want to modifier it.
# safe the old prefix
my $old_prefix = $log->get_prefix();
# set a new one for a code part in your script
$log->set_prefix("my new prefix");
# now set the your old prefix again
$log->set_prefix($old_prefix);
Or you want to add something to the current prefix:
$log->set_prefix($log->get_prefix."add something");
errstr()
Call "errstr()" if you want to get the last error message. That is useful with "die_on_errors". If you set this option to 0 then the handler wouldn't croak if a simple write operation fails. Set "die_on_errors" to control it yourself. "errstr()" is only useful with "new()", "close()" and the log level methods.
$log->info("Hello World!") or die $log->errstr;
Or
$error_string = $log->errstr
unless $log->info("Hello World!");
The exception is that the handler croaks in any case if the call of "new()" fails because on missing params or wrong settings!
my $log = Log::Handler::Simple->new(filename => 'file.log', mode => 'foo bar');
That would croak, because the option "mode" except "append" or "trunc" or "excl".
If you set the option "fileopen" to 1 - the default - to open the log file permanent and the call of "new" fails then you can absorb the error.
my $log = Log::Handler::Simple->new(
filename => 'file.log',
die_on_errors => 0
) or warn Log::Handler::Simple->errstr;
close()
Call "close()" if you want to close the log file.This option is only useful if you set the option "fileopen" to 1 and if you want to close the log file yourself. If you don't call "close()" the log file will be closed automatically before exit.
trace()
This method is very useful if you want to print "caller()" informations to the log file. In contrast to the log level methods this method prints "caller()" informations to the log file in any case and you don't need to activate the debugger with the option "debug". Example:
my $log = Log::Handler::Simple->new( filename => \*STDOUT );
$log->trace("caller informations:");
Jun 05 21:20:32 [TRACE] caller informations
CALL(2): package(main) filename(./log-handler-test.pl) line(22) subroutine(Log::Handler::Simple::trace) hasargs(1)
CALL(1): package(Log::Handler::Simple) filename(/usr/local/share/perl/5.8.8/Log/Handler.pm) line(941) subroutine(Log::Handler::Simple::_print) hasargs(1)
CALL(0): package(Log::Handler::Simple) filename(/usr/local/share/perl/5.8.8/Log/Handler.pm) line(1097) subroutine(Devel::Backtrace::new) hasargs(1) wantarray(0)
Maybe you like to print caller informations to the log file if an unexpected error occurs.
$SIG{__DIE__} = sub { $log->trace(@_) };
Take a look at the examples of the options "debug", "debug_mode" and "debug_skip" for more informations.
OPTIONS
filename
With "filename" you can set a file name, a GLOBREF or you can set a string as an alias for STDOUT or STDERR. The default is STDOUT for this option.Set a file name:
my $log = Log::Handler::Simple->new( filename => 'file.log' );
Set a GLOBREF
open FH, '>', 'file.log' or die $!;
my $log = Log::Handler::Simple->new( filename => \*FH );
Or the same with
open my $fh, '>', 'file.log' or die $!;
my $log = Log::Handler::Simple->new( filename => $fh );
Set STDOUT or STDERR
my $log = Log::Handler::Simple->new( filename => \*STDOUT );
# or
my $log = Log::Handler::Simple->new( filename => \*STDERR );
If the option "filename" is set in a config file and you want to debug to your screen then you can set *STDOUT or *STDERR as a string.
my $log = Log::Handler::Simple->new( filename => '*STDOUT' );
# or
my $log = Log::Handler::Simple->new( filename => '*STDERR' );
That is not possible:
my $log = Log::Handler::Simple->new( filename => '*FH' );
Note that if you set a GLOBREF to "filename" some options will be forced (overwritten) and you have to control the handles yourself. The forced options are
fileopen => 1
filelock => 0
reopen => 0
filelock
Maybe it's desirable to lock the log file by each write operation because a lot of processes write at the same time to the log file. You can set the option "filelock" to activate or deactivate the locking.
0 - no file lock
1 - exclusive lock (LOCK_EX) and unlock (LOCK_UN) by each write operation (default)
fileopen
Open a log file transient or permanent.
0 - open and close the logfile by each write operation
1 - open the logfile if C<new()> called and try to reopen the
file if C<reopen> is set to 1 and the inode of the file has changed (default)
reopen
This option works only if option "fileopen" is set to 1.
0 - deactivate
1 - try to reopen the log file if the inode changed (default)
fileopen and reopen
Please note that it's better to set "reopen" and "fileopen" to 0 on Windows because Windows unfortunately haven't the faintest idea of inodes.To write your code independent you should control it:
my $os_is_win = $^O =~ /win/i ? 0 : 1;
my $log = Log::Handler::Simple->new(
filename => 'file.log',
mode => 'append',
fileopen => $os_is_win
);
If you set "fileopen" to 0 then it implies that "reopen" has no importance.
mode
There are three possible modes to open a log file.
append - O_WRONLY | O_APPEND | O_CREAT
excl - O_WRONLY | O_EXCL | O_CREAT (default)
trunc - O_WRONLY | O_TRUNC | O_CREAT
"append" would open the log file in any case and appends the messages at the end of the log file.
"excl" would fail by open the log file if the log file already exists. This is the default option because some security reasons.
"trunc" would truncate the complete log file if it exists. Please take care to use this option.
Take a look to the documentation of "sysopen()" to get more informations.
autoflush
0 - autoflush off
1 - autoflush on (default)
permissions
The option "permissions" sets the permission of the file if it creates and must be set as a octal value. The permission need to be in octal and are modified by your process's current ``umask''.That means that you have to use the unix style permissions such as "chmod". 0640 is the default permission for this option. That means that the owner got read and write permissions and users in the same group got only read permissions. All other users got no access.
Take a look to the documentation of "sysopen()" to get more informations.
timeformat
You can set "timeformat" with a date and time format that will be coverted by 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
newline
This helpful option appends a newline to the log message if it not exist.
0 - inactive (default)
1 - active - appends a newline to the log message if not exist
prefix
Set "prefix" to define your own prefix for each message. The default value is ``[<--LEVEL-->] ''.``<--LEVEL-->'' is replaced with the current message level. Default example:
$log->alert("message ...");
would log
Feb 01 12:56:31 [ALERT] message ...
If you set "prefix" to
prefix => 'foo <--LEVEL--> bar: '
$log->info("foobar");
then it would log
Feb 01 12:56:31 foo INFO bar: foobar
Take a look to the EXAMPLES to see more.
maxlevel and minlevel
With these options it's possible to set the log levels for your program. The log levels are:
7 - debug
6 - info
5 - notice, note
4 - warning, warn
3 - error, err
2 - critical, crit
1 - alert
0 - emergency, emerg
The levels "note", "err", "crit" and "emerg" are just shortcuts.
It's possible to set the log level as a string or as number. The default "maxlevel" is 4 and the default "minlevel" is 0.
Example: If "maxlevel" is set to 4 and "minlevel" to 0 then the levels emergency (emerg), alert, critical (crit) and error (err) are active and would be logged to the log file.
You can set both to 8 or "nothing" if you don't want to log any message.
rewrite_to_stderr
Set this option to 1 if you want that Log::Handler::Simple prints messages to STDERR if the message couldn't print to the log file. The default is 0.die_on_errors
Set "die_on_errors" to 0 if you don't want that the handler croaks if normal operations fail.
0 - will not die on errors
1 - will die (e.g. croak) on errors
The exception is that the handler croaks in any case if the call of "new()" fails because on missing params or wrong settings.
utf8
If this option is set to 1 then UTF-8 will be set with "binmode()" on the output filehandle.debug
You can activate a simple debugger that writes "caller()" informations for each log level that would log to the log file. The debugger is logging all defined values except "hints" and "bitmask". Set "debug" 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 block mode looks like this:
use strict;
use warnings;
use Log::Handler::Simple;
my $log = Log::Handler::Simple->new(
maxlevel => 'debug',
debug => 1,
debug_mode => 1
);
sub test1 { $log->debug() }
sub test2 { &test1; }
&test2;
Output:
Apr 26 12:54:11 [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::Simple::__ANON__) hasargs(1)
CALL(1): package(Log::Handler::Simple) filename(/usr/local/share/perl/5.8.8/Log/Handler.pm) line(713) subroutine(Log::Handler::Simple::_print) hasargs(1)
CALL(0): package(Log::Handler::Simple) 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::Simple::__ANON__
hasargs 1
CALL(1):
package Log::Handler::Simple
filename /usr/local/share/perl/5.8.8/Log/Handler.pm
line 681
subroutine Log::Handler::Simple::_print
hasargs 1
CALL(0):
package Log::Handler::Simple
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 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::Simple::__ANON__) hasargs(1)
EXAMPLES
Simple example to log all level:
use Log::Handler::Simple;
my $log = Log::Handler::Simple->new(
filename => 'file1.log',
mode => 'append',
newline => 1,
maxlevel => 7,
minlevel => 0
);
$log->debug("this is a debug message");
$log->info("this is a info message");
$log->notice("this is a notice");
$log->note("this is a notice as well");
$log->warning("this is a warning");
$log->warn("this is a warning as well");
$log->error("this is a error message");
$log->err("this is a error message as well");
$log->critical("this is a critical message");
$log->crit("this is a critical message as well");
$log->alert("this is a alert message");
$log->emergency("this is a emergency message");
$log->emerg("this is a emergency message as well");
Would log
Feb 01 12:56:31 [DEBUG] this is a debug message
Feb 01 12:56:31 [INFO] this is a info message
Feb 01 12:56:31 [NOTICE] this is a notice
Feb 01 12:56:31 [NOTE] this is a notice as well
Feb 01 12:56:31 [WARNING] this is a warning
Feb 01 12:56:31 [WARN] this is a warning
Feb 01 12:56:31 [ERROR] this is a error message
Feb 01 12:56:31 [ERR] this is a error message as well
Feb 01 12:56:31 [CRITICAL] this is a critical message
Feb 01 12:56:31 [CRIT] this is a critial message as well
Feb 01 12:56:31 [ALERT] this is a alert message
Feb 01 12:56:31 [EMERGENCY] this is a emergency message
Feb 01 12:56:31 [EMERG] this is a emergency message as well
Just a notice:
use Log::Handler::Simple;
my $log = Log::Handler::Simple->new(
filename => '/var/run/pid-file1',
mode => 'trunc',
maxlevel => 5,
minlevel => 5,
prefix => '',
timeformat => ''
);
$log->note("$$");
Would truncate /var/run/pid-file1 and write just the pid to the logfile.
Selfmade prefix:
use Log::Handler::Simple;
use Sys::Hostname;
my $hostname = hostname;
my $pid = $$;
my $progname = $0;
$progname =~ s@.*[/\\]@@;
my $log = Log::Handler::Simple->new(
filename => "${progname}.log",
mode => 'append',
maxlevel => 6,
newline => 1,
prefix => "${hostname}[$pid] [<--LEVEL-->] $progname: "
);
$log->info("Hello World!");
$log->warning("There is something wrong!");
Would log:
Feb 01 12:56:31 hostname[8923] [INFO] progname: Hello world
Feb 01 12:56:31 hostname[8923] [WARNING] progname: There is something wrong!
is_* example:
use Log::Handler::Simple;
use Data::Dumper;
my $log = Log::Handler::Simple->new(
filename => 'file1.log',
mode => 'append',
maxlevel => 4,
);
my %hash = (foo => 1, bar => 2);
$log->debug("\n".Dumper(\%hash))
if $log->is_debug();
Would NOT dump %hash to the $log object!
die_on_errors example:
use Log::Handler::Simple;
use Data::Dumper;
my $log = Log::Handler::Simple->new(
filename => 'file1.log',
mode => 'append',
die_on_errors => 0
) or die Log::Handler::Simple->errstr();
if ($log->is_debug()) {
$log->debug("\n".Dumper(\%hash))
or die $log->errstr();
}
PREREQUISITES
Fcntl - for flock(), O_APPEND, O_WRONLY, O_EXCL and O_CREATE
POSIX - to generate the time stamp with strftime()
Params::Validate - to validate all options
Devel::Backtrace - to backtrace caller()
Carp - to croak() on errors if die_on_errors is active
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#perlde
If you send me a mail then add Log::Handler::Simple 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.
Contenus ©2006-2024 Benjamin Poulain
Design ©2006-2024 Maxime Vantorre