Log::Log4perl::MDC - Mapped Diagnostic Context |
Log::Log4perl::MDC - Mapped Diagnostic Context
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.
$value
under key $key
in the map.
%X{key}
in
Log::Log4perl::Layout::PatternLayout
.
If no value exists to the given key, the string "[undef]"
is being returned.
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).
Mike Schilli, <log4perl@perlmeister.com>
Log::Log4perl::MDC - Mapped Diagnostic Context |