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@perlmeister.com> and Kevin Goess <cpan@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@lists.sourceforge.net

       Authors (please contact them via the list above, not directly): Mike Schilli
       <m@perlmeister.com>, Kevin Goess <cpan@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.