org.apache.openjpa.datacache

Class ConcurrentQueryCache

java.lang.Object

org.apache.openjpa.lib.util.concurrent.AbstractConcurrentEventManager

org.apache.openjpa.datacache.AbstractQueryCache

org.apache.openjpa.datacache.ConcurrentQueryCache

All Implemented Interfaces:

Serializable, QueryCache, TypesChangedListener, RemoteCommitListener, Configurable, Closeable, EventManager

public class ConcurrentQueryCache
extends AbstractQueryCache
implements RemoteCommitListener

A QueryCache implementation that is optimized for concurrent access. When the cache fill up, values to remove from the cache are chosen randomly. Due to race conditions, it is possible that a get call might not retur a cached instance if that instance is being transferred between internal datastructures.

Since:

0.4.1

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.openjpa.datacache.AbstractQueryCache

AbstractQueryCache.Default<T>, AbstractQueryCache.EvictPolicy

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	_lru

Fields inherited from class org.apache.openjpa.datacache.AbstractQueryCache

conf, entityTimestampMap, evictPolicy, log

Fields inherited from class org.apache.openjpa.lib.util.concurrent.AbstractConcurrentEventManager

_listeners

Constructor Summary

Constructors

Constructor and Description
ConcurrentQueryCache()

Method Summary

Modifier and Type	Method and Description
protected void	clearInternal() Clear the cache.
CacheMap	getCacheMap() Returns the underlying CacheMap that this cache is using.
int	getCacheSize() Returns the maximum number of unpinned objects to keep hard references to.
AbstractQueryCache.EvictPolicy	getEvictPolicy() Returns the eviction policy of the query cache
protected QueryResult	getInternal(QueryKey qk) Return the list for the given key.
boolean	getLru()
int	getSoftReferenceSize() Returns the maximum number of unpinned objects to keep soft references to.
void	initialize(DataCacheManager mgr) Initialize any resources associated with the given DataCacheManager.
protected Collection	keySet() Return a threadsafe view of the keys in this cache.
protected CacheMap	newCacheMap() Return the map to use as an internal cache.
protected boolean	pinInternal(QueryKey qk) Pin an object to the cache.
protected QueryResult	putInternal(QueryKey qk, QueryResult result) Add the given result to the cache, returning the old result under the given key.
protected QueryResult	removeInternal(QueryKey qk) Remove the result under the given key from the cache.
void	setCacheSize(int size) Sets the maximum number of unpinned objects to keep hard references to.
void	setLru(boolean l)
void	setSoftReferenceSize(int size) Sets the maximum number of unpinned objects to keep soft references to.
protected boolean	unpinInternal(QueryKey qk) Unpin an object from the cache.
void	writeLock() Obtain a write lock on the cache.
void	writeUnlock() Release the write lock on the cache.

Methods inherited from class org.apache.openjpa.datacache.AbstractQueryCache

addTypesChangedListener, afterCommit, clear, close, close, count, endConfiguration, fireEvent, get, getAllEntityTimestamp, getEnableStatistics, getName, getStatistics, isClosed, newListenerCollection, onTypesChanged, pin, put, remove, removeAllInternal, removeTypesChangedListener, setConfiguration, setEnableStatistics, setEvictPolicy, setName, startConfiguration, unpin, updateEntityTimestamp

Methods inherited from class org.apache.openjpa.lib.util.concurrent.AbstractConcurrentEventManager

addListener, fireEvent, getListeners, hasListener, hasListeners, isFailFast, removeListener, setFailFast

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.openjpa.event.RemoteCommitListener

afterCommit, close

Field Detail

_lru

protected boolean _lru

Constructor Detail

ConcurrentQueryCache

public ConcurrentQueryCache()

Method Detail

getCacheMap

public CacheMap getCacheMap()

Returns the underlying CacheMap that this cache is using. This is not an unmodifiable view on the map, so care should be taken with this reference. Implementations should probably not modify the contents of the cache, but should only use this reference to obtain cache metrics. Additionally, this map may contain expired data. Removal of timed-out data is done in a lazy fashion, so the actual size of the map may be greater than the number of non-expired query results in cache.

getCacheSize

public int getCacheSize()

Returns the maximum number of unpinned objects to keep hard references to.

setCacheSize

public void setCacheSize(int size)

Sets the maximum number of unpinned objects to keep hard references to. If the map contains more unpinned objects than size, then this method will result in the cache flushing old values.

getSoftReferenceSize

public int getSoftReferenceSize()

Returns the maximum number of unpinned objects to keep soft references to. Defaults to -1.

setSoftReferenceSize

public void setSoftReferenceSize(int size)

Sets the maximum number of unpinned objects to keep soft references to. If the map contains more soft references than size, then this method will result in the cache flushing values.

initialize

public void initialize(DataCacheManager mgr)

Description copied from interface: QueryCache

Initialize any resources associated with the given DataCacheManager.

Specified by:

initialize in interface QueryCache

Overrides:

initialize in class AbstractQueryCache

writeLock

public void writeLock()

Description copied from interface: QueryCache

Obtain a write lock on the cache.

Specified by:

writeLock in interface QueryCache

writeUnlock

public void writeUnlock()

Description copied from interface: QueryCache

Release the write lock on the cache.

Specified by:

writeUnlock in interface QueryCache

newCacheMap

protected CacheMap newCacheMap()

Return the map to use as an internal cache.

getInternal

protected QueryResult getInternal(QueryKey qk)

Description copied from class: AbstractQueryCache

Return the list for the given key.

Specified by:

getInternal in class AbstractQueryCache

putInternal

protected QueryResult putInternal(QueryKey qk,
                                  QueryResult result)

Description copied from class: AbstractQueryCache

Add the given result to the cache, returning the old result under the given key.

Specified by:

putInternal in class AbstractQueryCache

removeInternal

protected QueryResult removeInternal(QueryKey qk)

Description copied from class: AbstractQueryCache

Remove the result under the given key from the cache.

Specified by:

removeInternal in class AbstractQueryCache

clearInternal

protected void clearInternal()

Description copied from class: AbstractQueryCache

Clear the cache.

Specified by:

clearInternal in class AbstractQueryCache

pinInternal

protected boolean pinInternal(QueryKey qk)

Description copied from class: AbstractQueryCache

Pin an object to the cache.

Specified by:

pinInternal in class AbstractQueryCache

unpinInternal

protected boolean unpinInternal(QueryKey qk)

Description copied from class: AbstractQueryCache

Unpin an object from the cache.

Specified by:

unpinInternal in class AbstractQueryCache

keySet

protected Collection keySet()

Description copied from class: AbstractQueryCache

Return a threadsafe view of the keys in this cache. This collection must be iterable without risk of concurrent modification exceptions. It does not have to implement contains() efficiently or use set semantics.

Specified by:

keySet in class AbstractQueryCache

getEvictPolicy

public AbstractQueryCache.EvictPolicy getEvictPolicy()

Returns the eviction policy of the query cache

Overrides:

getEvictPolicy in class AbstractQueryCache

Returns:

-- returns a String value of evictPolicy attribute

setLru

public void setLru(boolean l)

getLru

public boolean getLru()