ConcurrentQueryCache (OpenJPA 0.9.7-incubating API)

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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:: QueryCache, TypesChangedListener, RemoteCommitListener, Configurable, Closeable, EventManager

public class ConcurrentQueryCache
extends AbstractQueryCache
implements RemoteCommitListener
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

Field Summary

Fields inherited from class org.apache.openjpa.datacache.AbstractQueryCache
`conf, log`

Constructor Summary
`ConcurrentQueryCache()`

Method Summary
`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.
`protected QueryResult`	`getInternal(QueryKey qk)` Return the list for the given key.
`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`	`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, endConfiguration, fireEvent, get, isClosed, newListenerCollection, onTypesChanged, pin, put, remove, removeAllInternal, removeTypesChangedListener, setConfiguration, startConfiguration, unpin`

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`

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.