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package oracle.toplink.essentials.internal.sessions;
import java.util.*;
import oracle.toplink.essentials.descriptors.ClassDescriptor;
import oracle.toplink.essentials.internal.ejb.cmp3.base.RepeatableWriteUnitOfWork;
import oracle.toplink.essentials.internal.identitymaps.*;
import oracle.toplink.essentials.internal.sessions.IdentityMapAccessor;
import oracle.toplink.essentials.expressions.*;
import oracle.toplink.essentials.exceptions.*;
import oracle.toplink.essentials.internal.queryframework.JoinedAttributeManager;
import oracle.toplink.essentials.queryframework.*;
/**
* INTERNAL:
* IdentityMapAccessor subclass for UnitOfWork
* Overrides some initialization functionality and some behavoir having to do with
* getting objects from identity maps.
*/
public class UnitOfWorkIdentityMapAccessor extends IdentityMapAccessor {
public UnitOfWorkIdentityMapAccessor(AbstractSession session, IdentityMapManager identityMapManager) {
super(session, identityMapManager);
}
/**
* INTERNAL:
* Return if their is an object for the primary key.
*/
public boolean containsObjectInIdentityMap(Vector primaryKey, Class theClass, ClassDescriptor descriptor) {
if (getIdentityMapManager().containsKey(primaryKey, theClass, descriptor)) {
return true;
}
return ((UnitOfWorkImpl)getSession()).getParent().getIdentityMapAccessorInstance().containsObjectInIdentityMap(primaryKey, theClass, descriptor);
}
/**
* INTERNAL:
* This method overrides the getAllFromIdentityMap method in Session. Invalidated Objects
* will always be returned from a UnitOfWork.
*/
public Vector getAllFromIdentityMap(Expression selectionCriteria, Class theClass, AbstractRecord translationRow, InMemoryQueryIndirectionPolicy valueHolderPolicy, boolean shouldReturnInvalidatedObjects) throws QueryException {
return super.getAllFromIdentityMap(selectionCriteria, theClass, translationRow, valueHolderPolicy, true);
}
/**
* INTERNAL:
* Overide the getFromIdentityMapWithDeferredLock method on the session to ensure that
* invalidated objects are always returned since this is a UnitOfWork
*/
public Object getFromIdentityMapWithDeferredLock(Vector primaryKey, Class theClass, boolean shouldReturnInvalidatedObjects, ClassDescriptor descriptor) {
return super.getFromIdentityMapWithDeferredLock(primaryKey, theClass, true, descriptor);
}
/**
* INTERNAL:
* Return the object from the identity map with the primary key and class.
* The parent's cache must be checked after the child's,
* if found in the parent, it must be registered/cloned (but must avoid looping).
* Note: in a UnitOfWork, invalidated objects will always be returned from the identity map
* In the parent session, only return the object if it has not been Invalidated
*/
public Object getFromIdentityMap(Vector primaryKey, Class theClass, boolean shouldReturnInvalidatedObjects, ClassDescriptor descriptor, JoinedAttributeManager joinedAttributeManager) {
Object objectFromCache = super.getFromIdentityMap(primaryKey, theClass, true, descriptor, joinedAttributeManager);
if (objectFromCache != null) {
return objectFromCache;
}
//Bug#4613774 In the parent session, only return the object if it has not been Invalidated
return getAndCloneCacheKeyFromParent(primaryKey, theClass, shouldReturnInvalidatedObjects, descriptor, joinedAttributeManager);
}
/**
* INTERNAL:
* This method will return the object from the parent and clone it.
* If the uow is RepeatableWriteUnitOfWork and the original object
* from the parent corresponds to deleted unregistered object clone,
* then the latter returned.
*/
protected Object getAndCloneCacheKeyFromParent(Vector primaryKey, Class theClass, boolean shouldReturnInvalidatedObjects, ClassDescriptor descriptor, JoinedAttributeManager joinedAttributeManager) {
// Note: Objects returned from the parent's identity map should include invalidated
// objects. This is important because this internal method is used in the existence
// check in the UnitOfWork.
CacheKey cacheKey = ((UnitOfWorkImpl)getSession()).getParent().getIdentityMapAccessorInstance().getCacheKeyForObject(primaryKey, theClass, descriptor);
if ((cacheKey == null) && ((UnitOfWorkImpl)getSession()).getParent().isUnitOfWork()) {//for nested unit of work
//make parent clone and register object
((UnitOfWorkIdentityMapAccessor)((UnitOfWorkImpl)getSession()).getParent().getIdentityMapAccessorInstance()).getAndCloneCacheKeyFromParent(primaryKey, theClass, shouldReturnInvalidatedObjects, descriptor, joinedAttributeManager);
//get the cachekey that was created in the parent.
cacheKey = ((UnitOfWorkImpl)getSession()).getParent().getIdentityMapAccessorInstance().getCacheKeyForObject(primaryKey, theClass, descriptor);
}
Object objectFromCache = null;
// this check could be simplfied to one line but would create a window
// in which GC could remove the object and we would end up with a null pointer
// as well we must inspect the cacheKey without locking on it.
if ((cacheKey != null) && (shouldReturnInvalidatedObjects || !descriptor.getCacheInvalidationPolicy().isInvalidated(cacheKey, System.currentTimeMillis()))) {
synchronized (cacheKey.getMutex()) {
//if the object in the cachekey is null but the key is acquired then
//someone must be rebuilding it or creating a new one. Sleep until
// it's finished. A plain wait here would be more efficient but we may not
// get notified for quite some time (ie deadlock) if the other thread
//is building the object. Must wait and not sleep in order for the monitor to be released
objectFromCache = cacheKey.getObject();
try {
while (cacheKey.isAcquired() && (objectFromCache == null)) {
cacheKey.getMutex().wait(5);
}
} catch (InterruptedException ex) {
}
if (objectFromCache == null) {
return null;
}
}
} else {
return null;
}
// Consider read-only class CR#4094
if (getSession().isClassReadOnly(theClass, descriptor)) {
// PERF: Just return the original object.
return objectFromCache;
}
if(getSession() instanceof RepeatableWriteUnitOfWork ) {
Object unregisteredDeletedClone = ((RepeatableWriteUnitOfWork)getSession()).getUnregisteredDeletedCloneForOriginal(objectFromCache);
if(unregisteredDeletedClone != null) {
return unregisteredDeletedClone;
}
}
return ((UnitOfWorkImpl)getSession()).cloneAndRegisterObject(objectFromCache, cacheKey, joinedAttributeManager);
}
/**
* INTERNAL:
* Reset the entire object cache,
* ** be careful using this.
* This method blows away both this session's and its parents caches,
* this includes the server cache or any other cache.
* This throws away any objects that have been read in.
* Extreme caution should be used before doing this because object identity will no longer
* be maintained for any objects currently read in. This should only be called
* if the application knows that it no longer has references to object held in the cache.
*/
public void initializeAllIdentityMaps() {
super.initializeAllIdentityMaps();
((UnitOfWorkImpl)getSession()).getParent().getIdentityMapAccessor().initializeAllIdentityMaps();
}
}
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