org.eclipse.persistence.sessions.interceptors

Class CacheInterceptor

java.lang.Object

org.eclipse.persistence.sessions.interceptors.CacheInterceptor

All Implemented Interfaces:

java.lang.Cloneable, IdentityMap

public abstract class CacheInterceptor
extends java.lang.Object
implements IdentityMap

Purpose: Define a class through which Cache access can be intercepted.

Description: EclipseLink makes extensive use of caching functionality. This class provides the mechanism for intercepting the cache access. Once intercepted applications can allow the process to continue by calling the method on the class attribute targetIdentityMap as described in the API javadocs or redirect the process entirely. * As with IdentityMaps an entire class inheritance hierarchy will share the same interceptor.

To implement a CacheInterceptor users should subclass this class implementing those methods they wish to intercept.

Configuration: Interceptors may be added to a session by using a Session or Descriptor customizer to set the class name of the interceptor on the target ClassDescriptor through the method setCacheInterceptorClass(Class).

Constructor Summary

Constructors

Constructor and Description
CacheInterceptor(IdentityMap targetIdentityMap, AbstractSession interceptedSession)

Method Summary

Modifier and Type	Method and Description
CacheKey	acquireDeferredLock(java.lang.Object primaryKey, boolean isCacheCheckComplete) Acquire a deferred lock on the object.
CacheKey	acquireLock(java.lang.Object primaryKey, boolean forMerge, boolean isCacheCheckComplete) Acquire an active lock on the object.
CacheKey	acquireLockNoWait(java.lang.Object primaryKey, boolean forMerge) Acquire an active lock on the object, if not already locked.
CacheKey	acquireLockWithWait(java.lang.Object primaryKey, boolean forMerge, int wait) Acquire an active lock on the object, if not already locked.
CacheKey	acquireReadLockOnCacheKey(java.lang.Object primaryKey) Acquire a read lock on the object.
CacheKey	acquireReadLockOnCacheKeyNoWait(java.lang.Object primaryKey) Acquire a read lock on the object, if not already locked.
abstract java.lang.Object	clone() Clone the map and all of the CacheKeys.
void	collectLocks(java.util.HashMap threadList) Add all locked CacheKeys to the map grouped by thread.
boolean	containsKey(java.lang.Object primaryKey) Return true if an CacheKey with the primary key is in the map.
java.util.Enumeration	elements() Allow for the cache to be iterated on.
java.lang.Object	get(java.lang.Object primaryKey) Return the object cached in the identity map or null if it could not be found.
abstract java.util.Map<java.lang.Object,CacheKey>	getAllCacheKeysFromIdentityMapWithEntityPK(java.lang.Object[] pkList, ClassDescriptor descriptor, AbstractSession session) ADVANCED: Using a list of Entity PK this method will attempt to bulk load the entire list from the cache.
abstract java.util.Map<java.lang.Object,java.lang.Object>	getAllFromIdentityMapWithEntityPK(java.lang.Object[] pkList, ClassDescriptor descriptor, AbstractSession session) ADVANCED: Using a list of Entity PK this method will attempt to bulk load the entire list from the cache.
CacheKey	getCacheKey(java.lang.Object primaryKey, boolean forMerge) Get the cache key (with object) for the primary key.
CacheKey	getCacheKeyForLock(java.lang.Object primaryKey) Get the cache key (with object) for the primary key.
ClassDescriptor	getDescriptor() Return the descriptor that this is the map for.
java.lang.Class	getDescriptorClass() Return the class that this is the map for.
int	getMaxSize()
int	getSize() Return the number of CacheKeys in the IdentityMap.
int	getSize(java.lang.Class myClass, boolean recurse) Return the number of actual objects of type myClass in the IdentityMap.
IdentityMap	getTargetIdenttyMap() Return the instance of the IdentityMap that this intercpetor is wrapping.
java.lang.Object	getWrapper(java.lang.Object primaryKey) Get the wrapper object from the cache key associated with the given primary key, this is used for EJB2.
java.lang.Object	getWriteLockValue(java.lang.Object primaryKey) Get the write lock value from the cache key associated to the primarykey.
java.util.Enumeration	keys() Allow for the CacheKeys to be iterated on.
java.util.Enumeration	keys(boolean checkReadLocks) Allow for the CacheKeys to be iterated on.
void	lazyRelationshipLoaded(java.lang.Object rootEntity, ValueHolderInterface valueHolder, ForeignReferenceMapping mapping) Notify the cache that a lazy relationship has been triggered in the object and the cache may need to be updated
CacheKey	put(java.lang.Object primaryKey, java.lang.Object object, java.lang.Object writeLockValue, long readTime) Store the object in the cache at its primary key.
java.lang.Object	remove(CacheKey cacheKey) Remove the CacheKey from the map.
java.lang.Object	remove(java.lang.Object primaryKey, java.lang.Object object) Remove the CacheKey with the primaryKey from the map.
void	setDescriptor(ClassDescriptor descriptor) Set the descriptor that this is the map for.
void	setWrapper(java.lang.Object primaryKey, java.lang.Object wrapper) Update the wrapper object in the CacheKey associated with the given primaryKey, this is used for EJB2.
void	setWriteLockValue(java.lang.Object primaryKey, java.lang.Object writeLockValue) Update the write lock value of the CacheKey associated with the given primaryKey.
java.lang.String	toString()
void	updateMaxSize(int maxSize) This method will be used to update the max cache size, any objects exceeding the max cache size will be remove from the cache.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.eclipse.persistence.internal.identitymaps.IdentityMap

release

Constructor Detail

CacheInterceptor

public CacheInterceptor(IdentityMap targetIdentityMap,
                        AbstractSession interceptedSession)

Method Detail

acquireDeferredLock

public CacheKey acquireDeferredLock(java.lang.Object primaryKey,
                                    boolean isCacheCheckComplete)

Acquire a deferred lock on the object. This is used while reading if the object has relationships without indirection. This first thread will get an active lock. Other threads will get deferred locks, all threads will wait until all other threads are complete before releasing their locks.

Specified by:

acquireDeferredLock in interface IdentityMap

acquireLock

public CacheKey acquireLock(java.lang.Object primaryKey,
                            boolean forMerge,
                            boolean isCacheCheckComplete)

Acquire an active lock on the object. This is used by reading (when using indirection or no relationships) and by merge.

Specified by:

acquireLock in interface IdentityMap

acquireLockNoWait

public CacheKey acquireLockNoWait(java.lang.Object primaryKey,
                                  boolean forMerge)

Acquire an active lock on the object, if not already locked. This is used by merge for missing existing objects.

Specified by:

acquireLockNoWait in interface IdentityMap

acquireLockWithWait

public CacheKey acquireLockWithWait(java.lang.Object primaryKey,
                                    boolean forMerge,
                                    int wait)

Acquire an active lock on the object, if not already locked. This is used by merge for missing existing objects.

Specified by:

acquireLockWithWait in interface IdentityMap

acquireReadLockOnCacheKey

public CacheKey acquireReadLockOnCacheKey(java.lang.Object primaryKey)

Acquire a read lock on the object. This is used by UnitOfWork cloning. This will allow multiple users to read the same object but prevent writes to the object while the read lock is held.

Specified by:

acquireReadLockOnCacheKey in interface IdentityMap

acquireReadLockOnCacheKeyNoWait

public CacheKey acquireReadLockOnCacheKeyNoWait(java.lang.Object primaryKey)

Acquire a read lock on the object, if not already locked. This is used by UnitOfWork cloning. This will allow multiple users to read the same object but prevent writes to the object while the read lock is held.

Specified by:

acquireReadLockOnCacheKeyNoWait in interface IdentityMap

collectLocks

public void collectLocks(java.util.HashMap threadList)

Add all locked CacheKeys to the map grouped by thread. Used to print all the locks in the identity map.

Specified by:

collectLocks in interface IdentityMap

clone

public abstract java.lang.Object clone()

Clone the map and all of the CacheKeys. This is used by UnitOfWork commitAndResumeOnFailure to avoid corrupting the cache during a failed commit.

Specified by:

clone in interface IdentityMap

Overrides:

clone in class java.lang.Object

containsKey

public boolean containsKey(java.lang.Object primaryKey)

Return true if an CacheKey with the primary key is in the map. User API.

Specified by:

containsKey in interface IdentityMap

Parameters:

primaryKey - is the primary key for the object to search for.

elements

public java.util.Enumeration elements()

Allow for the cache to be iterated on. This method is only used during debugging when validateCache() has been called to print out the contents of the cache.

Specified by:

elements in interface IdentityMap

get

public java.lang.Object get(java.lang.Object primaryKey)

Return the object cached in the identity map or null if it could not be found. User API.

Specified by:

get in interface IdentityMap

getAllFromIdentityMapWithEntityPK

public abstract java.util.Map<java.lang.Object,java.lang.Object> getAllFromIdentityMapWithEntityPK(java.lang.Object[] pkList,
                                                                                                   ClassDescriptor descriptor,
                                                                                                   AbstractSession session)

ADVANCED: Using a list of Entity PK this method will attempt to bulk load the entire list from the cache. In certain circumstances this can have large performance improvements over loading each item individually.

Specified by:

getAllFromIdentityMapWithEntityPK in interface IdentityMap

Parameters:

pkList - List of Entity PKs to extract from the cache

descriptor - Descriptor type to be retrieved.

Returns:

Map of Entity PKs associated to the Entities that were retrieved

Throws:

QueryException

getAllCacheKeysFromIdentityMapWithEntityPK

public abstract java.util.Map<java.lang.Object,CacheKey> getAllCacheKeysFromIdentityMapWithEntityPK(java.lang.Object[] pkList,
                                                                                                    ClassDescriptor descriptor,
                                                                                                    AbstractSession session)

ADVANCED: Using a list of Entity PK this method will attempt to bulk load the entire list from the cache. In certain circumstances this can have large performance improvements over loading each item individually.

Specified by:

getAllCacheKeysFromIdentityMapWithEntityPK in interface IdentityMap

Parameters:

pkList - List of Entity PKs to extract from the cache

descriptor - Descriptor type to be retrieved.

Returns:

Map of Entity PKs associated to the Entities that were retrieved

Throws:

QueryException

getCacheKey

public CacheKey getCacheKey(java.lang.Object primaryKey,
                            boolean forMerge)

Get the cache key (with object) for the primary key.

Specified by:

getCacheKey in interface IdentityMap

getCacheKeyForLock

public CacheKey getCacheKeyForLock(java.lang.Object primaryKey)

Get the cache key (with object) for the primary key.

Specified by:

getCacheKeyForLock in interface IdentityMap

getDescriptor

public ClassDescriptor getDescriptor()

Return the descriptor that this is the map for.

Specified by:

getDescriptor in interface IdentityMap

getDescriptorClass

public java.lang.Class getDescriptorClass()

Return the class that this is the map for.

Specified by:

getDescriptorClass in interface IdentityMap

getMaxSize

public int getMaxSize()

Specified by:

getMaxSize in interface IdentityMap

Returns:

The maxSize for the IdentityMap (NOTE: some subclasses may use this differently).

getSize

public int getSize()

Return the number of CacheKeys in the IdentityMap. This may contain weak referenced objects that have been garbage collected.

Specified by:

getSize in interface IdentityMap

getSize

public int getSize(java.lang.Class myClass,
                   boolean recurse)

Return the number of actual objects of type myClass in the IdentityMap. Recurse = true will include subclasses of myClass in the count.

Specified by:

getSize in interface IdentityMap

getTargetIdenttyMap

public IdentityMap getTargetIdenttyMap()

Return the instance of the IdentityMap that this intercpetor is wrapping. Any call that is to be passed on to the underlying EclipseLink cache should be passed to this IdentityMap.

getWrapper

public java.lang.Object getWrapper(java.lang.Object primaryKey)

Get the wrapper object from the cache key associated with the given primary key, this is used for EJB2.

Specified by:

getWrapper in interface IdentityMap

getWriteLockValue

public java.lang.Object getWriteLockValue(java.lang.Object primaryKey)

Get the write lock value from the cache key associated to the primarykey. User API.

Specified by:

getWriteLockValue in interface IdentityMap

keys

public java.util.Enumeration keys()

Allow for the CacheKeys to be iterated on.

Specified by:

keys in interface IdentityMap

keys

public java.util.Enumeration keys(boolean checkReadLocks)

Allow for the CacheKeys to be iterated on. - value should be true if readloacks are to be used, false otherwise.

Specified by:

keys in interface IdentityMap

Parameters:

checkReadLocks - - true if readLocks should be checked, false otherwise.

lazyRelationshipLoaded

public void lazyRelationshipLoaded(java.lang.Object rootEntity,
                                   ValueHolderInterface valueHolder,
                                   ForeignReferenceMapping mapping)

Notify the cache that a lazy relationship has been triggered in the object and the cache may need to be updated

Specified by:

lazyRelationshipLoaded in interface IdentityMap

put

public CacheKey put(java.lang.Object primaryKey,
                    java.lang.Object object,
                    java.lang.Object writeLockValue,
                    long readTime)

Store the object in the cache at its primary key. This is used by InsertObjectQuery, typically into the UnitOfWork identity map. Merge and reads do not use put, but acquireLock. Also an advanced (very) user API.

Specified by:

put in interface IdentityMap

Parameters:

primaryKey - is the primary key for the object.

object - is the domain object to cache.

writeLockValue - is the current write lock value of object, if null the version is ignored.

remove

public java.lang.Object remove(java.lang.Object primaryKey,
                               java.lang.Object object)

Remove the CacheKey with the primaryKey from the map. This is used by DeleteObjectQuery and merge. This is also an advanced (very) user API.

Specified by:

remove in interface IdentityMap

remove

public java.lang.Object remove(CacheKey cacheKey)

Remove the CacheKey from the map.

Specified by:

remove in interface IdentityMap

updateMaxSize

public void updateMaxSize(int maxSize)

This method will be used to update the max cache size, any objects exceeding the max cache size will be remove from the cache. Please note that this does not remove the object from the identityMap, except in the case of the CacheIdentityMap.

Specified by:

updateMaxSize in interface IdentityMap

setDescriptor

public void setDescriptor(ClassDescriptor descriptor)

Set the descriptor that this is the map for.

Specified by:

setDescriptor in interface IdentityMap

setWrapper

public void setWrapper(java.lang.Object primaryKey,
                       java.lang.Object wrapper)

Update the wrapper object in the CacheKey associated with the given primaryKey, this is used for EJB2.

Specified by:

setWrapper in interface IdentityMap

setWriteLockValue

public void setWriteLockValue(java.lang.Object primaryKey,
                              java.lang.Object writeLockValue)

Update the write lock value of the CacheKey associated with the given primaryKey. This is used by UpdateObjectQuery, and is also an advanced (very) user API.

Specified by:

setWriteLockValue in interface IdentityMap

toString

public java.lang.String toString()

Specified by:

toString in interface IdentityMap

Overrides:

toString in class java.lang.Object