Class: cache_definition  - X-Ref

The cache definition class.

Cache definitions need to be defined in db/caches.php files.
They can be constructed with the following options.

Required settings:
+ mode
[int] Sets the mode for the definition. Must be one of cache_store::MODE_*

Optional settings:
+ simplekeys
[bool] Set to true if your cache will only use simple keys for its items.
Simple keys consist of digits, underscores and the 26 chars of the english language. a-zA-Z0-9_
If true the keys won't be hashed before being passed to the cache store for gets/sets/deletes. It will be
better for performance and possible only becase we know the keys are safe.
+ simpledata
[bool] If set to true we know that the data is scalar or array of scalar.
+ requireidentifiers
[array] An array of identifiers that must be provided to the cache when it is created.
+ requiredataguarantee
[bool] If set to true then only stores that can guarantee data will remain available once set will be used.
+ requiremultipleidentifiers
[bool] If set to true then only stores that support multiple identifiers will be used.
+ requirelockingread
[bool] If set to true then a lock will be gained before reading from the cache store. It is recommended not to use
this setting unless 100% absolutely positively required. Remember 99.9% of caches will NOT need this setting.
This setting will only be used for application caches presently.
+ requirelockingwrite
[bool] If set to true then a lock will be gained before writing to the cache store. As above this is not recommended
unless truly needed. Please think about the order of your code and deal with race conditions there first.
This setting will only be used for application caches presently.
+ maxsize
[int] If set this will be used as the maximum number of entries within the cache store for this definition.
Its important to note that cache stores don't actually have to acknowledge this setting or maintain it as a hard limit.
+ overrideclass
[string] A class to use as the loader for this cache. This is an advanced setting and will allow the developer of the
definition to take 100% control of the caching solution.
Any class used here must inherit the cache_loader interface and must extend default cache loader for the mode they are
using.
+ overrideclassfile
[string] Suplements the above setting indicated the file containing the class to be used. This file is included when
required.
+ datasource
[string] A class to use as the data loader for this definition.
Any class used here must inherit the cache_data_loader interface.
+ datasourcefile
[string] Supplements the above setting indicating the file containing the class to be used. This file is included when
required.
+ staticacceleration
The cache loader will keep an array of the items set and retrieved to the cache during the request.
Consider using this setting when you know that there are going to be many calls to the cache for the same information.
Requests for data in this array will be ultra fast, but it will cost memory.
+ staticaccelerationsize
[int] This supplements the above setting by limiting the number of items in the static acceleration array.
Tweaking this setting lower will allow you to minimise the memory implications above while hopefully still managing to
offset calls to the cache store.
+ ttl
[int] A time to live for the data (in seconds). It is strongly recommended that you don't make use of this and
instead try to create an event driven invalidation system.
Not all cache stores will support this natively and there are undesired performance impacts if the cache store does not.
+ mappingsonly
[bool] If set to true only the mapped cache store(s) will be used and the default mode store will not. This is a super
advanced setting and should not be used unless absolutely required. It allows you to avoid the default stores for one
reason or another.
+ invalidationevents
[array] An array of events that should cause this cache to invalidate some or all of the items within it.
+ sharingoptions
[int] The sharing options that are appropriate for this definition. Should be the sum of the possible options.
+ defaultsharing
[int] The default sharing option to use. It's highly recommended that you don't set this unless there is a very
specific reason not to use the system default.
+ canuselocalstore
[bool] The cache is able to safely run with multiple copies on different webservers without any need for administrator
intervention to ensure that data stays in sync across nodes.  This is usually managed by a revision
system as seen in modinfo cache or language cache.  Requiring purge on upgrade is not sufficient as
it requires administrator intervention on each node to make it work.

For examples take a look at lib/db/caches.php

Class: file  - X-Ref

Class: file  - X-Ref

Class: does  - X-Ref

Class: does  - X-Ref

Class: file  - X-Ref

Class: does  - X-Ref