Cache::Cache(3) User Contributed Perl Documentation Cache::Cache(3)NAMECache::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 CHICache::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
perl v5.14.1 2009-03-01 Cache::Cache(3)
