org.apache.openjpa.datacache
Interface QueryCache

All Superinterfaces:

Closeable, TypesChangedListener

All Known Implementing Classes:

AbstractQueryCache, ConcurrentQueryCache, DelegatingQueryCache

public interface QueryCache
extends TypesChangedListener, Closeable

Interface that must be implemented by any level 2 query cache used by OpenJPA. These methods should be threadsafe. Most query cache implementations will probably implement Configurable to receive a handle to the system configuration on construction.

Since:

0.2.5

Author:

Patrick Linskey

Method Summary

void	addTypesChangedListener(TypesChangedListener listen) Add a new types event listener to this cache.
void	clear() Remove all data from this cache.
void	close() Free the resources used by this cache.
QueryResult	get(QueryKey qk) Return a list of oids for the given query key.
void	initialize(DataCacheManager manager) Initialize any resources associated with the given DataCacheManager.
boolean	pin(QueryKey qk) Pin the value stored under qk into the cache.
QueryResult	put(QueryKey qk, QueryResult oids) Set the list of OIDs for the given query key.
QueryResult	remove(QueryKey qk) Remove the value stored under the given query key.
boolean	removeTypesChangedListener(TypesChangedListener listen) Remove an types event listener from this cache.
boolean	unpin(QueryKey qk) Unpin the value stored under key into the cache.
void	writeLock() Obtain a write lock on the cache.
void	writeUnlock() Release the write lock on the cache.

Methods inherited from interface org.apache.openjpa.datacache.TypesChangedListener

onTypesChanged

Method Detail

initialize

void initialize(DataCacheManager manager)

Initialize any resources associated with the given DataCacheManager.

Since:

0.4.1

get

QueryResult get(QueryKey qk)

Return a list of oids for the given query key. This is an unmodifiable list.

Returns:

The query results matching the given key, or null if none

put

QueryResult put(QueryKey qk,
                QueryResult oids)

Set the list of OIDs for the given query key. A reference to the given list will be stored in the query cache, so the list should not be modified after invoking this method.

Returns:

The previously cached value, or null if the key was not previously cached. See Map.put(K, V) for more information.

remove

QueryResult remove(QueryKey qk)

Remove the value stored under the given query key. This method is typically not invoked directly from outside the QueryCache class. Instead, the cache should be updated by implementing RemoteCommitListener, which will result in all queries that may be invalid being dropped.

Returns:

The previously cached value, or null if the key was not previously cached. See Map.remove(java.lang.Object) for more information.

clear

void clear()

Remove all data from this cache.

pin

boolean pin(QueryKey qk)

Pin the value stored under qk into the cache. This method guarantees that qk's value will not be expired if the cache exceeds its capacity. It causes this data to be ignored when determining whether or not the cache is full, effectively increasing the total amount of data stored in the cache. This method does not affect the behavior of remove(org.apache.openjpa.datacache.QueryKey) or TypesChangedListener.onTypesChanged(org.apache.openjpa.datacache.TypesChangedEvent).

Returns:

true if key's value was pinned into the cache; false if the key is not in the cache.

unpin

boolean unpin(QueryKey qk)

Unpin the value stored under key into the cache. This method reverses a previous invocation of pin(org.apache.openjpa.datacache.QueryKey). This method does not remove anything from the cache; it merely makes key's value a candidate for flushing from the cache.

Returns:

true if key's value was unpinned from the cache; false if the key is not in the cache.

writeLock

void writeLock()

Obtain a write lock on the cache.

writeUnlock

void writeUnlock()

Release the write lock on the cache.

addTypesChangedListener

void addTypesChangedListener(TypesChangedListener listen)

Add a new types event listener to this cache.

Since:

0.3.3

removeTypesChangedListener

boolean removeTypesChangedListener(TypesChangedListener listen)

Remove an types event listener from this cache.

Since:

0.3.3

close

void close()

Free the resources used by this cache.

Specified by:

close in interface Closeable