/*******************************************************************************
* Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.internal.sessions;
import java.util.Map;
import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.sessions.server.*;
import org.eclipse.persistence.queries.*;
import org.eclipse.persistence.internal.descriptors.ObjectBuilder;
import org.eclipse.persistence.internal.identitymaps.CacheKey;
import org.eclipse.persistence.internal.sessions.AbstractSession;
/**
* Provides isolation support by allowing a client session
* to have a local cache of the subset of the classes.
* This can be used to avoid caching frequently changing data,
* or for security or VPD purposes.
*/
public class IsolatedClientSession extends ClientSession {
public IsolatedClientSession(ServerSession parent, ConnectionPolicy connectionPolicy) {
super(parent, connectionPolicy);
// PERF: Cache the write-lock check to avoid cost of checking in every register/clone.
this.shouldCheckWriteLock = getDatasourceLogin().shouldSynchronizedReadOnWrite() || getDatasourceLogin().shouldSynchronizeWrites();
}
public IsolatedClientSession(ServerSession parent, ConnectionPolicy connectionPolicy, Map properties) {
super(parent, connectionPolicy, properties);
// PERF: Cache the write-lock check to avoid cost of checking in every register/clone.
this.shouldCheckWriteLock = getDatasourceLogin().shouldSynchronizedReadOnWrite() || getDatasourceLogin().shouldSynchronizeWrites();
}
/**
* INTERNAL:
* Set up the IdentityMapManager. This method allows subclasses of Session to override
* the default IdentityMapManager functionality.
*/
@Override
public void initializeIdentityMapAccessor() {
this.identityMapAccessor = new IsolatedClientSessionIdentityMapAccessor(this);
}
/**
* INTERNAL:
* Helper method to calculate whether to execute this query locally or send
* it to the server session.
*/
protected boolean shouldExecuteLocally(DatabaseQuery query) {
if (isIsolatedQuery(query)) {
return true;
}
return isInTransaction();
}
/**
* INTERNAL: Answers if this query is an isolated query and must be
* executed locally.
*/
protected boolean isIsolatedQuery(DatabaseQuery query) {
query.checkDescriptor(this);
ClassDescriptor descriptor = query.getDescriptor();
if (query.isDataModifyQuery() || query.isDataReadQuery() || (descriptor != null && descriptor.getCachePolicy().isIsolated())
|| (query.isObjectBuildingQuery() && ((ObjectBuildingQuery)query).shouldUseExclusiveConnection())) {
// For CR#4334 if in transaction stay on client session.
// That way client's write accessor will be used for all queries.
// This is to preserve transaction isolation levels.
// also if this is an isolated class and we are in an isolated session
//load locally.
return true;
}
return false;
}
/**
* INTERNAL:
* Returns the appropriate IdentityMap session for this descriptor. Sessions can be
* chained and each session can have its own Cache/IdentityMap. Entities can be stored
* at different levels based on Cache Isolation. This method will return the correct Session
* for a particular Entity class based on the Isolation Level and the attributes provided.
* <p>
* @param canReturnSelf true when method calls itself. If the path
* starting at <code>this</code> is acceptable. Sometimes true if want to
* move to the first valid session, i.e. executing on ClientSession when really
* should be on ServerSession.
* @param terminalOnly return the last session in the chain where the Enitity is stored.
* @return Session with the required IdentityMap
*/
@Override
public AbstractSession getParentIdentityMapSession(ClassDescriptor descriptor, boolean canReturnSelf, boolean terminalOnly) {
if (canReturnSelf && (descriptor == null || descriptor.getCachePolicy().isIsolated()
|| (descriptor.getCachePolicy().isProtectedIsolation() && !descriptor.shouldIsolateProtectedObjectsInUnitOfWork()
&& !terminalOnly))){
return this;
}
return getParent().getParentIdentityMapSession(descriptor, canReturnSelf, terminalOnly);
}
/**
* INTERNAL:
* For use within the merge process this method will get an object from the shared
* cache using a readlock. If a readlock is unavailable then the merge manager will be
* transitioned to deferred locks and a deferred lock will be used.
*/
@Override
protected CacheKey getCacheKeyFromTargetSessionForMerge(Object implementation, ObjectBuilder builder, ClassDescriptor descriptor, MergeManager mergeManager){
Object primaryKey = builder.extractPrimaryKeyFromObject(implementation, this, true);
CacheKey cacheKey = getIdentityMapAccessorInstance().getCacheKeyForObject(primaryKey, implementation.getClass(), descriptor, true);
return cacheKey;
}
/**
* INTERNAL:
* Gets the session which this query will be executed on.
* Generally will be called immediately before the call is translated,
* which is immediately before session.executeCall.
* <p>
* Since the execution session also knows the correct datasource platform
* to execute on, it is often used in the mappings where the platform is
* needed for type conversion, or where calls are translated.
* <p>
* Is also the session with the accessor. Will return a ClientSession if
* it is in transaction and has a write connection.
* @return a session with a live accessor
* @param query may store session name or reference class for brokers case
*/
@Override
public AbstractSession getExecutionSession(DatabaseQuery query) {
if (shouldExecuteLocally(query)) {
return this;
} else {
return this.parent.getExecutionSession(query);
}
}
/**
* PUBLIC:
* Return if this session is an isolated client session.
*/
@Override
public boolean isIsolatedClientSession() {
return true;
}
/**
* PUBLIC:
* Returns true if Protected Entities should be built within this session
*/
public boolean isProtectedSession(){
return true;
}
}