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ICache Configuration

As mentioned in the JCache Declarative Configuration section, the Hazelcast ICache extension offers additional configuration properties over the default JCache configuration. These additional properties include internal storage format, backup counts and eviction policy.

The declarative configuration for ICache is a superset of the previously discussed JCache configuration:

<cache>
  <!-- ... default cache configuration goes here ... -->
  <backup-count>1</backup-count>
  <async-backup-count>1</async-backup-count>
  <in-memory-format>BINARY</in-memory-format>
  <eviction size="10000" max-size-policy="ENTRY_COUNT" eviction-policy="LRU" />
</cache>
  • backup-count: The number of synchronous backups. Those backups are executed before the mutating cache operation is finished. The mutating operation is blocked. backup-count default value is 1.
  • async-backup-count: The number of asynchronous backups. Those backups are executed asynchronously so the mutating operation is not blocked and it will be done immediately. async-backup-count default value is 0.
  • in-memory-format: Defines the internal storage format. For more information, please see the In Memory Format section. Default is BINARY.
  • eviction: Defines the used eviction strategies and sizes for the cache. For more information on eviction, please see the JCache Eviction.
    • size: The maximum number of records or maximum size in bytes depending on the max-size-policy property. Size can be any integer between 0 and Integer.MAX_VALUE. Default max-size-policy is ENTRY_COUNT and default size is 10.000.
    • max-size-policy: The size policy property defines a maximum size. If maximum size is reached, the cache is evicted based on the eviction policy. Default max-size-policy is ENTRY_COUNT and default size is 10.000. The following eviction policies are available:
      • ENTRY_COUNT: Maximum number of cache entries in the cache. Available on heap based cache record store only.
      • USED_NATIVE_MEMORY_SIZE: Maximum used native memory size in megabytes for each instance. Available on High-Density Memory cache record store only.
      • USED_NATIVE_MEMORY_PERCENTAGE: Maximum used native memory size percentage for each instance. Available on High-Density Memory cache record store only.
      • FREE_NATIVE_MEMORY_SIZE: Maximum free native memory size in megabytes for each instance. Available on High-Density Memory cache record store only.
      • FREE_NATIVE_MEMORY_PERCENTAGE: Maximum free native memory size percentage for each instance. Available on High-Density Memory cache record store only.
    • eviction-policy: The defined eviction policy to compare values with to find the best matching eviction candidate. Default is LRU.
      • LRU: Less Recently Used - finds the best eviction candidate based on the lastAccessTime.
      • LFU: Less Frequently Used - finds the best eviction candidate based on the number of hits.

Since javax.cache.configuration.MutableConfiguration misses the above additional configuration properties, Hazelcast ICache extension provides an extended configuration class called com.hazelcast.config.CacheConfig. This class is an implementation of javax.cache.configuration.CompleteConfiguration and all the properties shown above can be configured using its corresponding setter methods.