org.eclipse.persistence.sessions.interceptors
Class CacheInterceptor

java.lang.Object
  org.eclipse.persistence.sessions.interceptors.CacheInterceptor

All Implemented Interfaces:

java.lang.Cloneable, org.eclipse.persistence.internal.identitymaps.IdentityMap

public abstract class CacheInterceptor
extends java.lang.Object
implements org.eclipse.persistence.internal.identitymaps.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 heirachy 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).

Field Summary

protected org.eclipse.persistence.internal.sessions.AbstractSession	interceptedSession
protected org.eclipse.persistence.internal.identitymaps.IdentityMap	targetIdentityMap This attribute stores the actual IdentityMap as configured by the user.

Constructor Summary

CacheInterceptor(org.eclipse.persistence.internal.identitymaps.IdentityMap targetIdentityMap, org.eclipse.persistence.internal.sessions.AbstractSession interceptedSession)

Method Summary

org.eclipse.persistence.internal.identitymaps.CacheKey	acquireDeferredLock(java.util.Vector primaryKey) Acquire a deferred lock on the object.
org.eclipse.persistence.internal.identitymaps.CacheKey	acquireLock(java.util.Vector primaryKey, boolean forMerge) Acquire an active lock on the object.
org.eclipse.persistence.internal.identitymaps.CacheKey	acquireLockNoWait(java.util.Vector primaryKey, boolean forMerge) Acquire an active lock on the object, if not already locked.
org.eclipse.persistence.internal.identitymaps.CacheKey	acquireLockWithWait(java.util.Vector primaryKey, boolean forMerge, int wait) Acquire an active lock on the object, if not already locked.
org.eclipse.persistence.internal.identitymaps.CacheKey	acquireReadLockOnCacheKey(java.util.Vector primaryKey) Acquire a read lock on the object.
org.eclipse.persistence.internal.identitymaps.CacheKey	acquireReadLockOnCacheKeyNoWait(java.util.Vector 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.util.Vector primaryKey) Return true if an CacheKey with the primary key is in the map.
protected abstract CacheKeyInterceptor	createCacheKeyInterceptor(org.eclipse.persistence.internal.identitymaps.CacheKey wrappedCacheKey)
java.util.Enumeration	elements() Allow for the cache to be iterated on.
java.lang.Object	get(java.util.Vector primaryKey) Return the object cached in the identity map or null if it could not be found.
org.eclipse.persistence.internal.identitymaps.CacheKey	getCacheKey(java.util.Vector primaryKey) Get the cache key (with object) for the primary key.
org.eclipse.persistence.internal.identitymaps.CacheKey	getCacheKeyForLock(java.util.Vector 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.
org.eclipse.persistence.internal.identitymaps.IdentityMap	getTargetIdenttyMap() Return the instance of the IdentityMap that this intercpetor is wrapping.
java.lang.Object	getWrapper(java.util.Vector 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.util.Vector 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. - value should be true if readloacks are to be used, false otherwise.
org.eclipse.persistence.internal.identitymaps.CacheKey	put(java.util.Vector 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(org.eclipse.persistence.internal.identitymaps.CacheKey cacheKey) Remove the CacheKey from the map.
java.lang.Object	remove(java.util.Vector 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.util.Vector 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.util.Vector 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, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

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

release

Field Detail

targetIdentityMap

protected org.eclipse.persistence.internal.identitymaps.IdentityMap targetIdentityMap

This attribute stores the actual IdentityMap as configured by the user.

interceptedSession

protected org.eclipse.persistence.internal.sessions.AbstractSession interceptedSession

Constructor Detail

CacheInterceptor

public CacheInterceptor(org.eclipse.persistence.internal.identitymaps.IdentityMap targetIdentityMap,
                        org.eclipse.persistence.internal.sessions.AbstractSession interceptedSession)

Method Detail

acquireDeferredLock

public org.eclipse.persistence.internal.identitymaps.CacheKey acquireDeferredLock(java.util.Vector primaryKey)

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 org.eclipse.persistence.internal.identitymaps.IdentityMap

acquireLock

public org.eclipse.persistence.internal.identitymaps.CacheKey acquireLock(java.util.Vector primaryKey,
                                                                          boolean forMerge)

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 org.eclipse.persistence.internal.identitymaps.IdentityMap

acquireLockNoWait

public org.eclipse.persistence.internal.identitymaps.CacheKey acquireLockNoWait(java.util.Vector 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 org.eclipse.persistence.internal.identitymaps.IdentityMap

acquireLockWithWait

public org.eclipse.persistence.internal.identitymaps.CacheKey acquireLockWithWait(java.util.Vector 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 org.eclipse.persistence.internal.identitymaps.IdentityMap

acquireReadLockOnCacheKey

public org.eclipse.persistence.internal.identitymaps.CacheKey acquireReadLockOnCacheKey(java.util.Vector 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 org.eclipse.persistence.internal.identitymaps.IdentityMap

acquireReadLockOnCacheKeyNoWait

public org.eclipse.persistence.internal.identitymaps.CacheKey acquireReadLockOnCacheKeyNoWait(java.util.Vector 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 org.eclipse.persistence.internal.identitymaps.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 org.eclipse.persistence.internal.identitymaps.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 org.eclipse.persistence.internal.identitymaps.IdentityMap

Overrides:

clone in class java.lang.Object

containsKey

public boolean containsKey(java.util.Vector primaryKey)

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

Specified by:

containsKey in interface org.eclipse.persistence.internal.identitymaps.IdentityMap

Parameters:

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

createCacheKeyInterceptor

protected abstract CacheKeyInterceptor createCacheKeyInterceptor(org.eclipse.persistence.internal.identitymaps.CacheKey wrappedCacheKey)

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 org.eclipse.persistence.internal.identitymaps.IdentityMap

get

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

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

Specified by:

get in interface org.eclipse.persistence.internal.identitymaps.IdentityMap

getCacheKey

public org.eclipse.persistence.internal.identitymaps.CacheKey getCacheKey(java.util.Vector primaryKey)

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

Specified by:

getCacheKey in interface org.eclipse.persistence.internal.identitymaps.IdentityMap

getCacheKeyForLock

public org.eclipse.persistence.internal.identitymaps.CacheKey getCacheKeyForLock(java.util.Vector primaryKey)

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

Specified by:

getCacheKeyForLock in interface org.eclipse.persistence.internal.identitymaps.IdentityMap

getDescriptor

public ClassDescriptor getDescriptor()

Return the descriptor that this is the map for.

Specified by:

getDescriptor in interface org.eclipse.persistence.internal.identitymaps.IdentityMap

getDescriptorClass

public java.lang.Class getDescriptorClass()

Return the class that this is the map for.

Specified by:

getDescriptorClass in interface org.eclipse.persistence.internal.identitymaps.IdentityMap

getMaxSize

public int getMaxSize()

Specified by:

getMaxSize in interface org.eclipse.persistence.internal.identitymaps.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 org.eclipse.persistence.internal.identitymaps.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 org.eclipse.persistence.internal.identitymaps.IdentityMap

getTargetIdenttyMap

public org.eclipse.persistence.internal.identitymaps.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.util.Vector 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 org.eclipse.persistence.internal.identitymaps.IdentityMap

getWriteLockValue

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

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

Specified by:

getWriteLockValue in interface org.eclipse.persistence.internal.identitymaps.IdentityMap

keys

public java.util.Enumeration keys()

Allow for the CacheKeys to be iterated on.

Specified by:

keys in interface org.eclipse.persistence.internal.identitymaps.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 org.eclipse.persistence.internal.identitymaps.IdentityMap

put

public org.eclipse.persistence.internal.identitymaps.CacheKey put(java.util.Vector 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 org.eclipse.persistence.internal.identitymaps.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.util.Vector 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 org.eclipse.persistence.internal.identitymaps.IdentityMap

remove

public java.lang.Object remove(org.eclipse.persistence.internal.identitymaps.CacheKey cacheKey)

Remove the CacheKey from the map.

Specified by:

remove in interface org.eclipse.persistence.internal.identitymaps.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 org.eclipse.persistence.internal.identitymaps.IdentityMap

setDescriptor

public void setDescriptor(ClassDescriptor descriptor)

Set the descriptor that this is the map for.

Specified by:

setDescriptor in interface org.eclipse.persistence.internal.identitymaps.IdentityMap

setWrapper

public void setWrapper(java.util.Vector 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 org.eclipse.persistence.internal.identitymaps.IdentityMap

setWriteLockValue

public void setWriteLockValue(java.util.Vector 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 org.eclipse.persistence.internal.identitymaps.IdentityMap

toString

public java.lang.String toString()

Specified by:

toString in interface org.eclipse.persistence.internal.identitymaps.IdentityMap

Overrides:

toString in class java.lang.Object