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NDC(3pm) User Contributed Perl Documentation NDC(3pm)
NAME
Log::Log4perl::NDC - Nested Diagnostic Context
DESCRIPTION
Log::Log4perl allows loggers to maintain global thread-specific data, called the Nested
Diagnostic Context (NDC).
At some point, the application might decide to push a piece of data onto the NDC stack,
which other parts of the application might want to reuse. For example, at the beginning of
a web request in a server, the application might decide to push the IP address of the
client onto the stack to provide it for other loggers down the road without having to pass
the data from function to function.
The Log::Log4perl::Layout::PatternLayout class even provides the handy %x placeholder
which is replaced by the blank-separated list of elements currently on the stack.
This module maintains a simple stack which you can push data on to, query what's on top,
pop it off again or delete the entire stack.
Its purpose is to provide a thread-specific context which all Log::Log4perl loggers can
refer to without the application having to pass around the context data between its
functions.
Since in 5.8.0 perl's threads don't share data only upon request, global data is by
definition thread-specific.
Log::Log4perl::NDC->push($text);
Push an item onto the stack. If the stack grows beyond the defined limit
($Log::Log4perl::NDC::MAX_SIZE), just the topmost element will be replated.
This is typically done when a context is entered.
Log::Log4perl::NDC->pop();
Discard the upmost element of the stack. This is typically done when a context is
left.
my $text = Log::Log4perl::NDC->get();
Retrieve the content of the stack as a string of blank-separated values without
disrupting the stack structure. Typically done by %x. If the stack is empty the value
"[undef]" is being returned.
Log::Log4perl::NDC->remove();
Reset the stack, remove all items.
Please note that all of the methods above are class methods, there's no instances of this
class.
LICENSE
Copyright 2002-2013 by Mike Schilli <m AT perlmeister.com> and Kevin Goess <cpan AT goess.org>.
This library is free software; you can redistribute it and/or modify it under the same
terms as Perl itself.
AUTHOR
Please contribute patches to the project on Github:
http://github.com/mschilli/log4perl
Send bug reports or requests for enhancements to the authors via our
MAILING LIST (questions, bug reports, suggestions/patches):
log4perl-devel AT lists.net
Authors (please contact them via the list above, not directly): Mike Schilli
<m AT perlmeister.com>, Kevin Goess <cpan AT goess.org>
Contributors (in alphabetical order): Ateeq Altaf, Cory Bennett, Jens Berthold, Jeremy
Bopp, Hutton Davidson, Chris R. Donnelly, Matisse Enzer, Hugh Esco, Anthony Foiani, James
FitzGibbon, Carl Franks, Dennis Gregorovic, Andy Grundman, Paul Harrington, Alexander
Hartmaier David Hull, Robert Jacobson, Jason Kohles, Jeff Macdonald, Markus Peter, Brett
Rann, Peter Rabbitson, Erik Selberg, Aaron Straup Cope, Lars Thegler, David Viner, Mac
Yang.
perl v5.32.1 2021-02-14 NDC(3pm)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
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Under GNU General Public License
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