The following document describes the various configuration options available for cache elements. Each element put into the cache can be configured independently. You can define element behavior in three ways: as a default setting, as a region setting, or at the element level.
The configuration below can be put in the cache.ccf configuration file. It establishes the default behavior for all regions. A region can override these defaults and an individual element can override these defaults and the region settings.
The default and region configuration settings have three components. They define what auxiliaries are available, how the cache should control the memory, and how the elements should behave. This configuration tells all regions to use an auxiliary called DC by default. It also establishes several settings for memory management (see Basic JCS Configuration for more information on the cacheattribute settings). In addition, by default all regions will take these element configuration settings.
These settings specify that elements are not eternal, i.e. they can expire. By default elements are considered eternal.
You can define the maximum life of an item by
setting the
MaxLife
parameter. If an item has been in the cache for
longer than the set number of seconds it will not be
retrieved on a get request. If you use the memory
shrinker the item will be actively removed from
memory. Currently there is no background disk
shrinker, but the disk cache does allow for a
maximum number of keys (see
Indexed Disk Cache
for more information on the disk cache settings).
You can define the maximum time an item can live
without being accessed by setting the
IdleTime
parameter. This is different than the
MaxMemoryIdleTimeSeconds
parameter, which just specifies how long an object
can be in memory before it is subjected to removal
or being spooled to a disk cache if it is available.
Note: the
IdleTime
parameter may not function properly for items
retrieved from disk, if you have a memory size of 0.
IsSpool
determines whether or not the element can go to disk, if
a disk cache is configured for the region.
IsRemote
determines whether or not the element can be sent to a
remote server, if one is configured for the region.
IsLateral
determines whether or not the element can be laterally
distributed, if a lateral auxiliary is configured for
the region.
Every element put into the cache has its own set of attributes. By default elements are given a copy of the default element attributes associated with a region. You can also specify the attributes to use for an element when you put it in the cache.
You can also programmatically modify the default element attributes.