##################################################
package Log::Log4perl::MDC;
##################################################

use 5.006;
use strict;
use warnings;

our %MDC_HASH = ();

###########################################
sub get {
###########################################
    my($class, $key) = @_;

    if($class ne __PACKAGE__) {
        # Somebody called us with Log::Log4perl::MDC::get($key)
        $key = $class;
    }

    if(exists $MDC_HASH{$key}) {
        return $MDC_HASH{$key};
    } else {
        return undef;
    }
}

###########################################
sub put {
###########################################
    my($class, $key, $value) = @_;

    if($class ne __PACKAGE__) {
        # Somebody called us with Log::Log4perl::MDC::put($key, $value)
        $value = $key;
        $key   = $class;
    }

    $MDC_HASH{$key} = $value;
}

###########################################
sub remove {
###########################################
    %MDC_HASH = ();

    1;
}

###########################################
sub get_context {
###########################################
    return \%MDC_HASH;
}

1;

__END__

=head1 NAME

Log::Log4perl::MDC - Mapped Diagnostic Context

=head1 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 C<"%X{key}"> placeholder in 
C<Log::Log4perl::Layout::PatternLayout>s.

=over 4

=item Log::Log4perl::MDC->put($key, $value);

Store a value C<$value> under key C<$key> in the map.

=item my $value = Log::Log4perl::MDC->get($key);

Retrieve the content of the map under the specified key.
Typically done by C<%X{key}> in
C<Log::Log4perl::Layout::PatternLayout>.
If no value exists to the given key, C<undef> is returned.

=item my $text = Log::Log4perl::MDC->remove();

Delete all entries from the map.

=item Log::Log4perl::MDC->get_context();

Returns a reference to the hash table.

=back

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 explicetly requested" the data structures
used are just global (and therefore thread-specific).

=head1 LICENSE

Copyright 2002-2012 by Mike Schilli E<lt>m@perlmeister.comE<gt> 
and Kevin Goess E<lt>cpan@goess.orgE<gt>.

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself. 

=head1 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, 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.