EclipseLink 2.2.0, build 'v20110202-r8913' API Reference

org.eclipse.persistence.config
Class CacheType

java.lang.Object
  extended by org.eclipse.persistence.config.CacheType

public class CacheType
extends java.lang.Object

Cache type persistence property values. The cache type defines the type of cache usage for the entities. Its usage depends on the memory and caching requirements of the entity. If no caching is desired at all the PersistenceUnitProperties.CACHE_SHARED_ should instead be used.

JPA persistence property Usage:

for all entities append DEFAULT suffix to CACHE_TYPE_ prefix:

properties.add(PersistenceUnitProperties.CACHE_TYPE_DEFAULT, CacheType.Weak);

for a single entity append either entity name or a full class name to CACHE_TYPE_ prefix:

properties.add(PersistenceUnitProperties.CACHE_TYPE_ + "Employee", CacheType.Weak);

properties.add(PersistenceUnitProperties.CACHE_TYPE_ + "my.test.Employee", CacheType.Weak);

Values are case-insensitive. "" could be used instead of default value CacheType.DEFAULT.

See Also:
PersistenceUnitProperties.CACHE_SHARED_, PersistenceUnitProperties.CACHE_TYPE_

Field Summary
static java.lang.String DEFAULT
          The default cache type is SoftWeak.
static java.lang.String Full
          A Soft cache holds all objects read by the application.
static java.lang.String HardWeak
          A HardWeak cache holds all objects in use by the application, and a fixed size sub-cache of MRU objects using normal (hard) references.
static java.lang.String NONE
          NONE does not cache any objects.
static java.lang.String Soft
          A Soft cache holds all objects read by the application, but allows any un-referenced objects to be free to garbage collection only when the JVM decides memory is low.
static java.lang.String SoftWeak
          A SoftWeak cache holds all objects in use by the application, and a fixed size sub-cache of MRU objects using Soft references.
static java.lang.String Weak
          A Weak cache holds all objects in use by the application, but allows any un-referenced objects to be free to garbage collection.
 
Constructor Summary
CacheType()
           
 
Method Summary
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

Weak

public static final java.lang.String Weak
A Weak cache holds all objects in use by the application, but allows any un-referenced objects to be free to garbage collection. This guarantees object identity, allows optimal garbage collection, but provides little caching benefit.

See Also:
Constant Field Values

Soft

public static final java.lang.String Soft
A Soft cache holds all objects read by the application, but allows any un-referenced objects to be free to garbage collection only when the JVM decides memory is low. This guarantees object identity, allows garbage collection when memory is low, and provides optimal caching benefit.

See Also:
Constant Field Values

SoftWeak

public static final java.lang.String SoftWeak
A SoftWeak cache holds all objects in use by the application, and a fixed size sub-cache of MRU objects using Soft references. It allows any un-referenced objects not in the sub-cache to be free to garbage collection, and the objects in the sub-cache are free to garbage collect only when the JVM decides memory is low. This guarantees object identity, allows configurable garbage collection, and provides configurable caching benefit.

See Also:
Constant Field Values

HardWeak

public static final java.lang.String HardWeak
A HardWeak cache holds all objects in use by the application, and a fixed size sub-cache of MRU objects using normal (hard) references. It allows any un-referenced objects not in the sub-cache to be free to garbage collection, but not objects in the sub-cache. This guarantees object identity, allows configurable garbage collection, and provides configurable caching benefit.

See Also:
Constant Field Values

Full

public static final java.lang.String Full
A Soft cache holds all objects read by the application. It does not allow any garbage collection. * This guarantees object identity, allows no garbage collection, and provides complete caching benefit.

WARNING: This cache type should only be used for a fixed sized number of objects, otherwise it will lead to an eventual memory leak.

See Also:
Constant Field Values

NONE

public static final java.lang.String NONE
NONE does not cache any objects. It allows any un-referenced objects to be free to garbage collection. This provides no object identity, allows complete garbage collection, and provides no caching benefit.

WARNING: This cache type should normally not be used. Instead disable the share cache through PersistenceUnitProperties.CACHE_SHARED_. Lack of object identity can lead to infinite loops for objects that have circular references and no indirection.

See Also:
PersistenceUnitProperties.CACHE_SHARED_, Constant Field Values

DEFAULT

public static final java.lang.String DEFAULT
The default cache type is SoftWeak.

See Also:
Constant Field Values
Constructor Detail

CacheType

public CacheType()

EclipseLink 2.2.0, build 'v20110202-r8913' API Reference