oracular (3) Cache::Cache.3pm.gz

NAME

       Cache::Cache -- the Cache interface.

DESCRIPTION

       The Cache modules are designed to assist a developer in persisting data for a specified period of time.
       Often these modules are used in web applications to store data locally to save repeated and redundant
       expensive calls to remote machines or databases.  People have also been known to use Cache::Cache for its
       straightforward interface in sharing data between runs of an application or invocations of a CGI-style
       script or simply as an easy to use abstraction of the filesystem or shared memory.

       The Cache::Cache interface is implemented by classes that support the get, set, remove, size, purge, and
       clear instance methods and their corresponding static methods for persisting data across method calls.

CACHE::CACHE VERSUS CHI

       Cache::Cache is in wide use and very stable, but has not changed in years and is no longer actively
       developed.

       CHI is the successor to Cache::Cache. It adheres to the basic Cache::Cache API but adds new features and
       drivers (e.g. FastMmap and Memcached), improves performance, and addresses limitations in the
       Cache::Cache implementation. The authors recommend the use of CHI going forward.

       Questions about Cache::Cache and CHI may be directed to the perl-cache mailing list at
       http://groups.google.com/group/perl-cache-discuss.

USAGE

       First, choose the best type of cache implementation for your needs.  The simplest cache is the
       MemoryCache, which is suitable for applications that are serving multiple sequential requests, and wish
       to avoid making redundant expensive queries, such as an Apache/mod_perl application talking to a
       database.  If you wish to share that data between processes, then perhaps the SharedMemoryCache is
       appropriate, although its behavior is tightly bound to the underlying IPC mechanism, which varies from
       system to system, and is unsuitable for large objects or large numbers of objects.  When the
       SharedMemoryCache is not acceptable, then FileCache offers all of the same functionality with similar
       performance metrics, and it is not limited in terms of the number of objects or their size.  If you wish
       to maintain a strict limit on the size of a file system based cache, then the SizeAwareFileCache is the
       way to go.  Similarly, the SizeAwareMemoryCache and the SizeAwareSharedMemoryCache add size management
       functionality to the MemoryCache and SharedMemoryCache classes respectively.

       Using a cache is simple.  Here is some sample code for instantiating and using a file system based cache.

         use Cache::FileCache;

         my $cache = new Cache::FileCache( );

         my $customer = $cache->get( $name );

         if ( not defined $customer )
         {
           $customer = get_customer_from_db( $name );
           $cache->set( $name, $customer, "10 minutes" );
         }

         return $customer;

CONSTANTS

       $EXPIRES_NEVER
           The item being set in the cache will never expire.

       $EXPIRES_NOW
           The item being set in the cache will expire immediately.

METHODS

       Clear( )
           Remove all objects from all caches of this type.

       Purge( )
           Remove all objects that have expired from all caches of this type.

       Size( )
           Returns the total size of all objects in all caches of this type.

       new( $options_hash_ref )
           Construct a new instance of a Cache::Cache. $options_hash_ref is a reference to a hash containing
           configuration options; see the section OPTIONS below.

       clear(  )
           Remove all objects from the namespace associated with this cache instance.

       get( $key )
           Returns the data associated with $key.

       get_object( $key )
           Returns the underlying Cache::Object object used to store the cached data associated with $key.  This
           will not trigger a removal of the cached object even if the object has expired.

       purge(  )
           Remove all objects that have expired from the namespace associated with this cache instance.

       remove( $key )
           Delete the data associated with the $key from the cache.

       set( $key, $data, [$expires_in] )
           Associates $data with $key in the cache. $expires_in indicates the time in seconds until this data
           should be erased, or the constant $EXPIRES_NOW, or the constant $EXPIRES_NEVER.  Defaults to
           $EXPIRES_NEVER.  This variable can also be in the extended format of "[number] [unit]", e.g., "10
           minutes".  The valid units are s, second, seconds, sec, m, minute, minutes, min, h, hour, hours, d,
           day, days, w, week, weeks, M, month, months, y, year, and years.  Additionally, $EXPIRES_NOW can be
           represented as "now" and $EXPIRES_NEVER can be represented as "never".

       set_object( $key, $object )
           Associates $key with Cache::Object $object.  Using set_object (as opposed to set) does not trigger an
           automatic removal of expired objects.

       size(  )
           Returns the total size of all objects in the namespace associated with this cache instance.

       get_namespaces( )
           Returns all the namespaces associated with this type of cache.

OPTIONS

       The options are set by passing in a reference to a hash containing any of the following keys:

       namespace
           The namespace associated with this cache.  Defaults to "Default" if not explicitly set.

       default_expires_in
           The default expiration time for objects place in the cache.  Defaults to $EXPIRES_NEVER if not
           explicitly set.

       auto_purge_interval
           Sets the auto purge interval.  If this option is set to a particular time ( in the same format as the
           expires_in ), then the purge( ) routine will be called during the first set after the interval
           expires.  The interval will then be reset.

       auto_purge_on_set
           If this option is true, then the auto purge interval routine will be checked on every set.

       auto_purge_on_get
           If this option is true, then the auto purge interval routine will be checked on every get.

PROPERTIES

       (get|set)_namespace( )
           The namespace of this cache instance

       get_default_expires_in( )
           The default expiration time for objects placed in this cache instance

       get_keys( )
           The list of keys specifying objects in the namespace associated with this cache instance

       get_identifiers( )
           This method has been deprecated in favor of get_keys( ).

       (get|set)_auto_purge_interval( )
           Accesses the auto purge interval.  If this option is set to a particular time ( in the same format as
           the expires_in ), then the purge( ) routine will be called during the first get after the interval
           expires.  The interval will then be reset.

       (get|set)_auto_purge_on_set( )
           If this property is true, then the auto purge interval routine will be checked on every set.

       (get|set)_auto_purge_on_get( )
           If this property is true, then the auto purge interval routine will be checked on every get.

SEE ALSO

       CHI - the successor to Cache::Cache

       Cache::Object, Cache::MemoryCache, Cache::FileCache, Cache::SharedMemoryCache, and
       Cache::SizeAwareFileCache

AUTHOR

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

       Last author:     $Author: dclinton $

       Copyright (C) 2001-2003 DeWitt Clinton