# Cache::CacheMetaData - phpMan

## 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 efficiently return information such as an
    objects size or an ordered list of identifiers 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