NAME

       Memoize - Expiry plug-in for Memoize that adds LRU cache expiration

SYNOPSIS

           use Memoize;

           memoize('slow_function',
                   TIE => [Memoize::ExpireLRU,
                           CACHESIZE => n,
                          ]);

       Note that one need not "use" this module. It will be found by the Memoize module.

       The argument to CACHESIZE must be an integer. Normally, this is all that is needed.
       Additional options are available:

               TUNECACHESIZE => m,
               INSTANCE => 'descriptive_name',
               TIE => '[DB_File, $filename, O_RDWR | O_CREATE, 0666]'

DESCRIPTION

       For the theory of Memoization, please see the Memoize module documentation. This module
       implements an expiry policy for Memoize that follows LRU semantics, that is, the last n
       results, where n is specified as the argument to the "CACHESIZE" parameter, will be
       cached.

PERFORMANCE TUNING

       It is often quite difficult to determine what size cache will give optimal results for a
       given function. To aid in determining this, ExpireLRU includes cache tuning support.
       Enabling this causes a definite performance hit, but it is often useful before code is
       released to production.

       To enable cache tuning support, simply specify the optional "TUNECACHESIZE" parameter with
       a size greater than that of the "CACHESIZE" parameter.

       When the program exits, a set of statistics will be printed to stderr. If multiple
       routines have been memoized, separate sets of statistics are printed for each routine. The
       default names are somewhat cryptic: this is the purpose of the "INSTANCE" parameter. The
       value of this parameter will be used as the identifier within the statistics report.

DIAGNOSTIC METHODS

       Two additional routines are available but not exported. Memoize::ExpireLRU::ShowStats
       returns a string identical to the statistics report printed to STDERR at the end of the
       program if test caches have been enabled; Memoize::ExpireLRU::DumpCache takes the instance
       name of a memoized function as a parameter, and returns a string describing the current
       state of that instance.

AUTHOR

       Brent B. Powers (B2Pi), Powers@B2Pi.com

       Copyright(c) 1999 Brent B. Powers. All rights reserved. This program is free software, you
       may redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

       Memoize