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## org.apache.openjpa.datacache
Class DelegatingDataCache

    java.lang.Object
      org.apache.openjpa.datacache.DelegatingDataCache

All Implemented Interfaces:
  DataCache, Closeable

    public class DelegatingDataCache

extends Object
implements DataCache

Delegating data cache that can also perform exception translation for use in facades. This cache allows its delegate to be null, in which case it returns default values for all operations.

Author:
  Abe White

Field Summary

Fields inherited from interface org.apache.openjpa.datacache.DataCache
`NAME_DEFAULT`

Constructor Summary
`DelegatingDataCache(DataCache cache)` Constructor.
`DelegatingDataCache(DataCache cache, RuntimeExceptionTranslator trans)`

Method Summary
`void` | `addExpirationListener(ExpirationListener listen)` Add a new expiration event listener to this cache.
`void` | `clear()` Remove all data from this cache.
`void` | `close()` Free the resources used by this cache.
`void` | `commit(Collection additions, Collection newUpdates, Collection existingUpdates, Collection deletes)` Perform a batch update of the cache.
`boolean` | `contains(Object oid)` Returns `true` if this cache contains data corresponding to `oid`; otherwise returns `false`.
`BitSet` | `containsAll(Collection oids)` Returns the indexes of the oids in this cache.
`boolean` | `equals(Object other)`
`DataCachePCData` | `get(Object oid)` Return the cached object for the given oid.
`DataCache` | `getDelegate()` Return the direct delegate.
`DataCache` | `getInnermostDelegate()` Return the native delegate.
`String` | `getName()` Returns a string name that can be used by end-user-visible code to identify this cache.
`int` | `hashCode()`
`void` | `initialize(DataCacheManager manager)` Initialize any resources associated with the given `DataCacheManager`.
`boolean` | `pin(Object oid)` Pin the value stored under `oid` into the cache.
`void` | `pinAll(Class cls, boolean subs)` Pin all oids for the given type.
`BitSet` | `pinAll(Collection oids)` Pin all oids to the cache.
`DataCachePCData` | `put(DataCachePCData value)` Set the cached value for the given instance.
`DataCachePCData` | `remove(Object oid)` Remove the value stored under the given oid.
`void` | `removeAll(Class cls, boolean subclasses)` Evict all values of a specified type.
`BitSet` | `removeAll(Collection oids)` Remove the values stored under the given oids.
`boolean` | `removeExpirationListener(ExpirationListener listen)` Remove an expiration event listener from this cache.
`void` | `setName(String name)` Sets a string name to be used to identify this cache to end-user needs.
`protected RuntimeException` | `translate(RuntimeException re)` Translate the OpenJPA exception.
`boolean` | `unpin(Object oid)` Unpin the value stored under `oid` from the cache.
`void` | `unpinAll(Class cls, boolean subs)` Unpin all oids associaed with the given type from the cache.
`BitSet` | `unpinAll(Collection oids)` Unpin all oids from the cache.
`void` | `update(DataCachePCData value)` Update the cached value for the given instance.
`void` | `writeLock()` Obtain a write lock on the cache.
`void` | `writeUnlock()` Release the write lock on the cache.

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### DelegatingDataCache

    public DelegatingDataCache(DataCache cache)

  Constructor. Supply delegate.

### DelegatingDataCache

    public DelegatingDataCache(DataCache cache,
                               RuntimeExceptionTranslator trans)

Method Detail

### getDelegate

    public DataCache getDelegate()

  Return the direct delegate.

### getInnermostDelegate

    public DataCache getInnermostDelegate()

  Return the native delegate.

### hashCode

    public int hashCode()

  Overrides:
    `hashCode` in class `Object`

### equals

    public boolean equals(Object other)

  Overrides:
    `equals` in class `Object`

### translate

    protected RuntimeException translate(RuntimeException re)

  Translate the OpenJPA exception.

### getName

    public String getName()

  Description copied from interface: `DataCache`
  Returns a string name that can be used by end-user-visible code to identify this cache.

  Specified by:
    `getName` in interface `DataCache`

### setName

    public void setName(String name)

  Description copied from interface: `DataCache`
  Sets a string name to be used to identify this cache to end-user needs.

  Specified by:
    `setName` in interface `DataCache`

### initialize

    public void initialize(DataCacheManager manager)

  Description copied from interface: `DataCache`
  Initialize any resources associated with the given `DataCacheManager`.

  Specified by:
    `initialize` in interface `DataCache`

### commit

    public void commit(Collection additions,
                       Collection newUpdates,
                       Collection existingUpdates,
                       Collection deletes)

  Description copied from interface: `DataCache`
  Perform a batch update of the cache. Add all `DataCachePCData` objects in `additions` and in `newUpdates`, make the appropriate modifications to all DataCachePCDatas in `existingUpdates`, and delete all OIDs in `deletes`. All changes made to cached data must be made via this method. It is this method that is responsible for performing any side-effects that should happen on meaningful cache changes. Implementations should bear in mind that the `deletes` collection may contain oids that are also in the `additions` map. This is possible because it is valid for a user to delete an object with a particular oid and then add that object in the same batch.

  Specified by:
    `commit` in interface `DataCache`
  Parameters:
    `additions` - A collection of `DataCachePCData` objects. These represent data that have been newly created, and thus must be added to the cache.
    `newUpdates` - A collection of `DataCachePCData` objects. These represent data that have been modified but were not originally in the cache, and thus must be added to the cache.
    `existingUpdates` - A collection of `DataCachePCData` objects. These represent data that have been modified and were originally loaded from the cache. It is up to the cache implementation to decide if these values must be re-enlisted in the cache. Some caches may return live data from `DataCache.get(java.lang.Object)` invocations, in which case these values need not be re-enlisted.
    `deletes` - A collection of object IDs that have been deleted and must therefore be dropped from the cache.

### contains

    public boolean contains(Object oid)

  Description copied from interface: `DataCache`
  Returns `true` if this cache contains data corresponding to `oid`; otherwise returns `false`.

  Specified by:
    `contains` in interface `DataCache`

### containsAll

    public BitSet containsAll(Collection oids)

  Description copied from interface: `DataCache`
  Returns the indexes of the oids in this cache.

  Specified by:
    `containsAll` in interface `DataCache`

### get

    public DataCachePCData get(Object oid)

  Description copied from interface: `DataCache`
  Return the cached object for the given oid. Modifying the returned object may or may not change the cached value; the `DataCache.update(org.apache.openjpa.datacache.DataCachePCData)` method should be used to re-cache any changed objects.

  Specified by:
    `get` in interface `DataCache`
  Returns:
    the object matching the given oid, or null if none

### put

    public DataCachePCData put(DataCachePCData value)

  Description copied from interface: `DataCache`
  Set the cached value for the given instance. This does not result in an update of other caches. Rather, it should only be used for loading clean data into the cache. Meaningful changes to the state of the cache should be made via the `DataCache.commit(java.util.Collection, java.util.Collection, java.util.Collection, java.util.Collection)` method.

  Specified by:
    `put` in interface `DataCache`
  Returns:
    The previously cached value, or `null` if the value was not previously cached. See `Map.put(K, V)` for more information.

### update

    public void update(DataCachePCData value)

  Description copied from interface: `DataCache`
  Update the cached value for the given instance. This does not result in an update of other caches. Rather, it should only be used for loading clean data into the cache. Meaningful changes to the state of the cache should be made via the `DataCache.commit(java.util.Collection, java.util.Collection, java.util.Collection, java.util.Collection)` method. A cache implementation may or may not return a live object from `DataCache.get(java.lang.Object)` invocations. If an object retrieved from a `DataCache.get(java.lang.Object)` operation needs to be updated, this method can be invoked instead of invoking `DataCache.put(org.apache.openjpa.datacache.DataCachePCData)`. The DataCache implementation can then make optimizations based on how its `DataCache.get(java.lang.Object)` method works.

  Specified by:
    `update` in interface `DataCache`

### remove

    public DataCachePCData remove(Object oid)

  Description copied from interface: `DataCache`
  Remove the value stored under the given oid. This does not result in an update of other caches. Rather, it should only be used for removing data in the cache. Meaningful changes to the state of the cache should be made via the `DataCache.commit(java.util.Collection, java.util.Collection, java.util.Collection, java.util.Collection)` method.

  Specified by:
    `remove` in interface `DataCache`
  Returns:
    The previously cached value, or `null` if the oid was not previously cached. See `Map.remove(java.lang.Object)` for more information.

### removeAll

    public BitSet removeAll(Collection oids)

  Description copied from interface: `DataCache`
  Remove the values stored under the given oids.

  Specified by:
    `removeAll` in interface `DataCache`
  Returns:
    the indexes of the removed oids
  See Also:
    `DataCache.remove(java.lang.Object)`

### removeAll

    public void removeAll(Class cls,
                          boolean subclasses)

  Description copied from interface: `DataCache`
  Evict all values of a specified type.

  Specified by:
    `removeAll` in interface `DataCache`

### clear

    public void clear()

  Description copied from interface: `DataCache`
  Remove all data from this cache. This does not result in an update of other caches. Rather, it should only be used for clearing the cache. Meaningful changes to the state of the cache should be made via the `DataCache.commit(java.util.Collection, java.util.Collection, java.util.Collection, java.util.Collection)` method.

  Specified by:
    `clear` in interface `DataCache`

### pin

    public boolean pin(Object oid)

  Description copied from interface: `DataCache`
  Pin the value stored under `oid` into the cache. This method guarantees that `oid`'s value will not be dropped by the caching algorithm. This method does not affect the behavior of `DataCache.remove(java.lang.Object)`.

  Specified by:
    `pin` in interface `DataCache`
  Returns:
    `true` if `oid`'s value was pinned into the cache; `false` if the oid is not in the cache.

### pinAll

    public BitSet pinAll(Collection oids)

  Description copied from interface: `DataCache`
  Pin all oids to the cache.

  Specified by:
    `pinAll` in interface `DataCache`
  Returns:
    the indexes of the pinned oids
  See Also:
    `DataCache.pin(java.lang.Object)`

### pinAll

    public void pinAll(Class cls,
                       boolean subs)

  Description copied from interface: `DataCache`
  Pin all oids for the given type.

  Specified by:
    `pinAll` in interface `DataCache`
    `subs` - Whether to include subclasses.

### unpin

    public boolean unpin(Object oid)

  Description copied from interface: `DataCache`
  Unpin the value stored under `oid` from the cache. This method reverses a previous invocation of `DataCache.pin(java.lang.Object)`. This method does not remove anything from the cache; it merely makes `oid`'s value a candidate for flushing from the cache.

  Specified by:
    `unpin` in interface `DataCache`
  Returns:
    `true` if `oid`'s value was unpinned from the cache; `false` if the oid is not in the cache.

### unpinAll

    public BitSet unpinAll(Collection oids)

  Description copied from interface: `DataCache`
  Unpin all oids from the cache.

  Specified by:
    `unpinAll` in interface `DataCache`
  Returns:
    the indexes of the unpinned oids
  See Also:
    `DataCache.unpin(java.lang.Object)`

### unpinAll

    public void unpinAll(Class cls,
                         boolean subs)

  Description copied from interface: `DataCache`
  Unpin all oids associaed with the given type from the cache.

  Specified by:
    `unpinAll` in interface `DataCache`
    `subs` - Whether to include subclasses.

### writeLock

    public void writeLock()

  Description copied from interface: `DataCache`
  Obtain a write lock on the cache.

  Specified by:
    `writeLock` in interface `DataCache`

### writeUnlock

    public void writeUnlock()

  Description copied from interface: `DataCache`
  Release the write lock on the cache.

  Specified by:
    `writeUnlock` in interface `DataCache`

### addExpirationListener

    public void addExpirationListener(ExpirationListener listen)

  Description copied from interface: `DataCache`
  Add a new expiration event listener to this cache.

  Specified by:
    `addExpirationListener` in interface `DataCache`

### removeExpirationListener

    public boolean removeExpirationListener(ExpirationListener listen)

  Description copied from interface: `DataCache`
  Remove an expiration event listener from this cache.

  Specified by:
    `removeExpirationListener` in interface `DataCache`

### close

    public void close()

  Description copied from interface: `DataCache`
  Free the resources used by this cache.

  Specified by:
    `close` in interface `DataCache`
  Specified by:
    `close` in interface `Closeable`

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