NAME

       Cache::CacheMetaData -- data about objects in the cache

DESCRIPTION

       The CacheMetaData object is used by size aware caches to keep track of the state of the
       cache and effeciently return information such as an objects size or an ordered list of
       indentifiers to be removed when a cache size is being limited.  End users will not
       normally use CacheMetaData directly.

SYNOPSIS

        use Cache::CacheMetaData;

        my $cache_meta_data = new Cache::CacheMetaData( );

        foreach my $key ( $cache->get_keys( ) )
        {
           my $object = $cache->get_object( $key ) or
             next;

           $cache_meta_data->insert( $object );
         }

        my $current_size = $cache_meta_data->get_cache_size( );

        my @removal_list = $cache_meta_data->build_removal_list( );

METHODS

       new(  )
           Construct a new Cache::CacheMetaData object

       insert( $object )
           Inform the CacheMetaData about the object $object in the cache.

       remove( $key )
           Inform the CacheMetaData that the object specified by $key is no longer in the cache.

       build_removal_list( )
           Create a list of the keys in the cache, ordered as follows:

           1) objects that expire now

           2) objects expiring at a particular time, with ties broken by the time at which they
           were least recently accessed

           3) objects that never expire, sub ordered by the time at which they were least
           recently accessed

           NOTE: This could be improved further by taking the size into account on accessed_at
           ties.  However, this type of tie is unlikely in normal usage.

       build_object_size( $key )
           Return the size of an object specified by $key.

PROPERTIES

       get_cache_size
           The total size of the objects in the cache

SEE ALSO

       Cache::Cache, Cache::CacheSizer, Cache::SizeAwareCache

AUTHOR

       Original author: DeWitt Clinton <dewitt@unto.net>

       Last author:     $Author: dclinton $

       Copyright (C) 2001-2003 DeWitt Clinton