1Cache::Cache(3)       User Contributed Perl Documentation      Cache::Cache(3)
2
3
4

NAME

6       Cache::Cache -- the Cache interface.
7

DESCRIPTION

9       The Cache modules are designed to assist a developer in persisting data
10       for a specified period of time.  Often these modules are used in web
11       applications to store data locally to save repeated and redundant
12       expensive calls to remote machines or databases.  People have also been
13       known to use Cache::Cache for its straightforward interface in sharing
14       data between runs of an application or invocations of a CGI-style
15       script or simply as an easy to use abstraction of the filesystem or
16       shared memory.
17
18       The Cache::Cache interface is implemented by classes that support the
19       get, set, remove, size, purge, and clear instance methods and their
20       corresponding static methods for persisting data across method calls.
21

CACHE::CACHE VERSUS CHI

23       Cache::Cache is in wide use and very stable, but has not changed in
24       years and is no longer actively developed.
25
26       CHI is the successor to Cache::Cache. It adheres to the basic
27       Cache::Cache API but adds new features and drivers (e.g. FastMmap and
28       Memcached), improves performance, and addresses limitations in the
29       Cache::Cache implementation. The authors recommend the use of CHI going
30       forward.
31
32       Questions about Cache::Cache and CHI may be directed to the perl-cache
33       mailing list at http://groups.google.com/group/perl-cache-discuss.
34

USAGE

36       First, choose the best type of cache implementation for your needs.
37       The simplest cache is the MemoryCache, which is suitable for
38       applications that are serving multiple sequential requests, and wish to
39       avoid making redundant expensive queries, such as an Apache/mod_perl
40       application talking to a database.  If you wish to share that data
41       between processes, then perhaps the SharedMemoryCache is appropriate,
42       although its behavior is tightly bound to the underlying IPC mechanism,
43       which varies from system to system, and is unsuitable for large objects
44       or large numbers of objects.  When the SharedMemoryCache is not
45       acceptable, then FileCache offers all of the same functionality with
46       similar performance metrics, and it is not limited in terms of the
47       number of objects or their size.  If you wish to maintain a strict
48       limit on the size of a file system based cache, then the
49       SizeAwareFileCache is the way to go.  Similarly, the
50       SizeAwareMemoryCache and the SizeAwareSharedMemoryCache add size
51       management functionality to the MemoryCache and SharedMemoryCache
52       classes respectively.
53
54       Using a cache is simple.  Here is some sample code for instantiating
55       and using a file system based cache.
56
57         use Cache::FileCache;
58
59         my $cache = new Cache::FileCache( );
60
61         my $customer = $cache->get( $name );
62
63         if ( not defined $customer )
64         {
65           $customer = get_customer_from_db( $name );
66           $cache->set( $name, $customer, "10 minutes" );
67         }
68
69         return $customer;
70

CONSTANTS

72       $EXPIRES_NEVER
73           The item being set in the cache will never expire.
74
75       $EXPIRES_NOW
76           The item being set in the cache will expire immediately.
77

METHODS

79       Clear( )
80           Remove all objects from all caches of this type.
81
82       Purge( )
83           Remove all objects that have expired from all caches of this type.
84
85       Size( )
86           Returns the total size of all objects in all caches of this type.
87
88       new( $options_hash_ref )
89           Construct a new instance of a Cache::Cache. $options_hash_ref is a
90           reference to a hash containing configuration options; see the
91           section OPTIONS below.
92
93       clear(  )
94           Remove all objects from the namespace associated with this cache
95           instance.
96
97       get( $key )
98           Returns the data associated with $key.
99
100       get_object( $key )
101           Returns the underlying Cache::Object object used to store the
102           cached data associated with $key.  This will not trigger a removal
103           of the cached object even if the object has expired.
104
105       purge(  )
106           Remove all objects that have expired from the namespace associated
107           with this cache instance.
108
109       remove( $key )
110           Delete the data associated with the $key from the cache.
111
112       set( $key, $data, [$expires_in] )
113           Associates $data with $key in the cache. $expires_in indicates the
114           time in seconds until this data should be erased, or the constant
115           $EXPIRES_NOW, or the constant $EXPIRES_NEVER.  Defaults to
116           $EXPIRES_NEVER.  This variable can also be in the extended format
117           of "[number] [unit]", e.g., "10 minutes".  The valid units are s,
118           second, seconds, sec, m, minute, minutes, min, h, hour, hours, d,
119           day, days, w, week, weeks, M, month, months, y, year, and years.
120           Additionally, $EXPIRES_NOW can be represented as "now" and
121           $EXPIRES_NEVER can be represented as "never".
122
123       set_object( $key, $object )
124           Associates $key with Cache::Object $object.  Using set_object (as
125           opposed to set) does not trigger an automatic removal of expired
126           objects.
127
128       size(  )
129           Returns the total size of all objects in the namespace associated
130           with this cache instance.
131
132       get_namespaces( )
133           Returns all the namespaces associated with this type of cache.
134

OPTIONS

136       The options are set by passing in a reference to a hash containing any
137       of the following keys:
138
139       namespace
140           The namespace associated with this cache.  Defaults to "Default" if
141           not explicitly set.
142
143       default_expires_in
144           The default expiration time for objects place in the cache.
145           Defaults to $EXPIRES_NEVER if not explicitly set.
146
147       auto_purge_interval
148           Sets the auto purge interval.  If this option is set to a
149           particular time ( in the same format as the expires_in ), then the
150           purge( ) routine will be called during the first set after the
151           interval expires.  The interval will then be reset.
152
153       auto_purge_on_set
154           If this option is true, then the auto purge interval routine will
155           be checked on every set.
156
157       auto_purge_on_get
158           If this option is true, then the auto purge interval routine will
159           be checked on every get.
160

PROPERTIES

162       (get|set)_namespace( )
163           The namespace of this cache instance
164
165       get_default_expires_in( )
166           The default expiration time for objects placed in this cache
167           instance
168
169       get_keys( )
170           The list of keys specifying objects in the namespace associated
171           with this cache instance
172
173       get_identifiers( )
174           This method has been deprecated in favor of get_keys( ).
175
176       (get|set)_auto_purge_interval( )
177           Accesses the auto purge interval.  If this option is set to a
178           particular time ( in the same format as the expires_in ), then the
179           purge( ) routine will be called during the first get after the
180           interval expires.  The interval will then be reset.
181
182       (get|set)_auto_purge_on_set( )
183           If this property is true, then the auto purge interval routine will
184           be checked on every set.
185
186       (get|set)_auto_purge_on_get( )
187           If this property is true, then the auto purge interval routine will
188           be checked on every get.
189

SEE ALSO

191       CHI - the successor to Cache::Cache
192
193       Cache::Object, Cache::MemoryCache, Cache::FileCache,
194       Cache::SharedMemoryCache, and Cache::SizeAwareFileCache
195

AUTHOR

197       Original author: DeWitt Clinton <dewitt@unto.net>
198
199       Last author:     $Author: dclinton $
200
201       Copyright (C) 2001-2003 DeWitt Clinton
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205perl v5.28.1                      2015-01-22                   Cache::Cache(3)
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