# Log::Log4perl::MDC - phpMan

## NAME
    [Log::Log4perl::MDC] - Mapped Diagnostic Context

## DESCRIPTION
    [Log::Log4perl] allows loggers to maintain global thread-specific data,
    called the Nested Diagnostic Context (NDC) and Mapped Diagnostic Context
    (MDC).

    The MDC is a simple thread-specific hash table, in which the application
    can stuff values under certain keys and retrieve them later via the
    "%X{key}" placeholder in "[Log::Log4perl::Layout::PatternLayout]"s.

    [Log::Log4perl::MDC]->put($key, $value);
        Store a value $value under key $key in the map.

    my $value = [Log::Log4perl::MDC]->get($key);
        Retrieve the content of the map under the specified key. Typically
        done by %X{key} in "[Log::Log4perl::Layout::PatternLayout]". If no
        value exists to the given key, "undef" is returned.

    my $text = [Log::Log4perl::MDC]->remove();
        Delete all entries from the map.

    [Log::Log4perl::MDC]->get_context();
        Returns a reference to the hash table.

    Please note that all of the methods above are class methods, there's no
    instances of this class. Since the thread model in perl 5.8.0 is "no
    shared data unless explicitly requested" the data structures used are
    just global (and therefore thread-specific).

## 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.