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.
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