org.apache.openjpa.datacache
Class ConcurrentQueryCache

java.lang.Object
  extended by org.apache.openjpa.lib.util.concurrent.AbstractConcurrentEventManager
      extended by org.apache.openjpa.datacache.AbstractQueryCache
          extended by 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

Field Summary
 
Fields inherited from class org.apache.openjpa.datacache.AbstractQueryCache
conf, log
 
Fields inherited from class org.apache.openjpa.lib.util.concurrent.AbstractConcurrentEventManager
_listeners
 
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.


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


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