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log::log4perl::ndc(3pm) [debian man page]

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. COPYRIGHT AND LICENSE
Copyright 2002-2009 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. perl v5.10.1 2010-07-21 NDC(3pm)

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MDC(3)							User Contributed Perl Documentation						    MDC(3)

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 explicetly requested" the data structures used are just global (and therefore thread-specific). COPYRIGHT AND LICENSE
Copyright 2002-2009 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. perl v5.12.1 2010-02-07 MDC(3)
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