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* as indicated by the @author tags. See the copyright.txt file in the
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*
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* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
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* License along with this software; if not, write to the Free
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package org.jboss.as.ejb3.component.entity.interceptors;
import javax.ejb.EJBException;
import javax.transaction.Status;
import javax.transaction.Synchronization;
import javax.transaction.TransactionSynchronizationRegistry;
import org.jboss.as.ee.component.Component;
import org.jboss.as.ee.component.ComponentInstance;
import org.jboss.as.ee.component.ComponentInstanceInterceptorFactory;
import org.jboss.as.ejb3.component.interceptors.AbstractEJBInterceptor;
import org.jboss.as.ejb3.component.entity.EntityBeanComponent;
import org.jboss.as.ejb3.component.entity.EntityBeanComponentInstance;
import org.jboss.as.ejb3.component.stateful.CurrentSynchronizationCallback;
import org.jboss.as.ejb3.tx.OwnableReentrantLock;
import org.jboss.invocation.Interceptor;
import org.jboss.invocation.InterceptorContext;
import org.jboss.invocation.InterceptorFactory;
import org.jboss.invocation.InterceptorFactoryContext;
import static org.jboss.as.ejb3.EjbLogger.EJB3_LOGGER;
import static org.jboss.as.ejb3.EjbLogger.ROOT_LOGGER;
import static org.jboss.as.ejb3.EjbMessages.MESSAGES;
/**
* {@link org.jboss.invocation.Interceptor} which manages {@link javax.transaction.Synchronization} semantics on an entity bean.
* <p/>
* For now we are using a completely synchronized approach to entity concurrency. There is at most 1 entity active for a given primary
* key at any time, and access is synchronized within a transaction.
*
* @author <a href="mailto:cdewolf@redhat.com">Carlo de Wolf</a>
* @author Jaikiran Pai
* @author Stuart Douglas
*/
public class EntityBeanSynchronizationInterceptor extends AbstractEJBInterceptor {
private final Object threadLock = new Object();
private final OwnableReentrantLock lock = new OwnableReentrantLock();
@Override
public Object processInvocation(InterceptorContext context) throws Exception {
final EntityBeanComponent component = getComponent(context, EntityBeanComponent.class);
final EntityBeanComponentInstance instance = (EntityBeanComponentInstance) context.getPrivateData(ComponentInstance.class);
//we do not synchronize for instances that are not associated with an identity
if (instance.getPrimaryKey() == null) {
return context.proceed();
}
final TransactionSynchronizationRegistry transactionSynchronizationRegistry = component.getTransactionSynchronizationRegistry();
if (ROOT_LOGGER.isTraceEnabled()) {
ROOT_LOGGER.trace("Trying to acquire lock: " + lock + " for entity bean " + instance + " during invocation: " + context);
}
// we obtain a lock in this synchronization interceptor because the lock needs to be tied to the synchronization
// so that it can released on the tx synchronization callbacks
final Object lockOwner = getLockOwner(transactionSynchronizationRegistry);
lock.pushOwner(lockOwner);
try {
lock.lock();
boolean syncRegistered = false;
synchronized (lock) {
//if the previous transaction was rolled back we re-load the entity bean state in the current TX
if(instance.isReloadRequired()) {
instance.reload();
}
if (ROOT_LOGGER.isTraceEnabled()) {
ROOT_LOGGER.trace("Acquired lock: " + lock + " for entity bean instance: " + instance + " during invocation: " + context);
}
if (context.getPrivateData(InternalInvocationMarker.class) == null) {
if (instance.isRemoved() || instance.isDiscarded()) {
final Object primaryKey = context.getPrivateData(EntityBeanComponent.PRIMARY_KEY_CONTEXT_KEY);
component.getCache().release(instance, true);
lock.unlock();
throw MESSAGES.instanceWasRemoved(component.getComponentName(), primaryKey);
}
}
Object currentTransactionKey = null;
try {
// get the key to current transaction associated with this thread
currentTransactionKey = transactionSynchronizationRegistry.getTransactionKey();
if (!instance.isSynchronizeRegistered()) {
// if this entity instance is already associated with a different transaction, then it's an error
// if the thread is currently associated with a tx, then register a tx synchronization
if (currentTransactionKey != null) {
// register a tx synchronization for this entity instance
final Synchronization entitySynchronization = new EntityBeanSynchronization(instance, lockOwner);
transactionSynchronizationRegistry.registerInterposedSynchronization(entitySynchronization);
syncRegistered = true;
if (ROOT_LOGGER.isTraceEnabled()) {
ROOT_LOGGER.trace("Registered tx synchronization: " + entitySynchronization + " for tx: " + currentTransactionKey +
" associated with stateful component instance: " + instance);
}
}
instance.setSynchronizationRegistered(true);
}
// proceed with the invocation
return context.proceed();
} finally {
// if the current call did *not* register a tx SessionSynchronization, then we have to explicitly mark the
// entity instance as "no longer in use". If it registered a tx EntityBeanSynchronization, then releasing the lock is
// taken care off by a tx synchronization callbacks.
//if is important to note that we increase the lock count on every invocation
//which means we need to release it on every invocation except for the one where we actually registered the TX synchronization
if (currentTransactionKey == null) {
instance.store();
releaseInstance(instance, true);
} else if (!syncRegistered) {
component.getCache().release(instance, true);
lock.unlock();
}
}
}
} finally {
lock.popOwner();
}
}
/**
* Releases the passed {@link EntityBeanComponentInstance} i.e. marks it as no longer in use. After releasing the
* instance, this method releases the lock, held by this thread, on the stateful component instance.
*
* @param instance The stateful component instance
* @param success
*/
private void releaseInstance(final EntityBeanComponentInstance instance, final boolean success) {
try {
instance.getComponent().getCache().release(instance, success);
} finally {
instance.setSynchronizationRegistered(false);
// release the lock on the SFSB instance
this.releaseLock();
}
}
/**
* Releases the lock, held by this thread, on the stateful component instance.
*/
private void releaseLock() {
lock.unlock();
if (ROOT_LOGGER.isTraceEnabled()) {
ROOT_LOGGER.trace("Released lock: " + lock);
}
}
private class EntityBeanSynchronization implements Synchronization {
private final EntityBeanComponentInstance componentInstance;
private final Object lockOwner;
EntityBeanSynchronization(EntityBeanComponentInstance componentInstance, final Object lockOwner) {
this.componentInstance = componentInstance;
this.lockOwner = lockOwner;
}
@Override
public void beforeCompletion() {
try {
CurrentSynchronizationCallback.set(CurrentSynchronizationCallback.CallbackType.BEFORE_COMPLETION);
synchronized (threadLock) {
//invoke the EJB store method within the transaction
try {
if (!componentInstance.isRemoved() && !componentInstance.isDiscarded() && componentInstance.getPrimaryKey() != null) {
componentInstance.store();
}
} catch (Throwable t) {
lock.pushOwner(lockOwner);
try {
handleThrowableInTxSync(componentInstance, t);
} finally {
lock.popOwner();
}
}
}
} finally {
CurrentSynchronizationCallback.clear();
}
}
@Override
public void afterCompletion(int status) {
//now release the lock
lock.pushOwner(lockOwner);
try {
final boolean success = status != Status.STATUS_MARKED_ROLLBACK
&& status != Status.STATUS_ROLLEDBACK &&
status != Status.STATUS_ROLLING_BACK;
if(!success) {
//the transaction did not succeed, we need to reload the entity bean state
componentInstance.setReloadRequired(true);
}
releaseInstance(componentInstance, success);
} catch (Exception e) {
EJB3_LOGGER.exceptionReleasingEntity(e);
} finally {
lock.popOwner();
}
}
/**
* Handles the exception that occurred during a {@link EntityBeanComponentInstance transaction synchronization} callback
* invocations.
* <p/>
* This method discards the <code>EntityBeanComponentInstance</code> and resets the {@link #transactionKey} before
* releasing the {@link #lock} held by this thread, for the <code>statefulSessionComponentInstance</code>
*
* @param instance The Entity component instance involved in the transaction
* @param t The {@link Throwable throwable}
* @return
*/
private Error handleThrowableInTxSync(final EntityBeanComponentInstance instance, final Throwable t) {
ROOT_LOGGER.discardingEntityComponent(instance, t);
try {
// discard the Entity instance
instance.discard();
} finally {
// release the lock associated with the SFSB instance
EntityBeanSynchronizationInterceptor.this.releaseLock();
}
// throw back an appropriate exception
if (t instanceof RuntimeException)
throw (RuntimeException) t;
if (t instanceof Error)
throw (Error) t;
throw (EJBException) new EJBException().initCause(t);
}
}
public static final InterceptorFactory FACTORY = new ComponentInstanceInterceptorFactory() {
@Override
protected Interceptor create(final Component component, final InterceptorFactoryContext context) {
return new EntityBeanSynchronizationInterceptor();
}
};
/**
* Use either the active transaction or the current thread as the lock owner
*
* @param transactionSynchronizationRegistry
* The synronization registry
* @return The lock owner
*/
private Object getLockOwner(final TransactionSynchronizationRegistry transactionSynchronizationRegistry) {
Object owner = transactionSynchronizationRegistry.getTransactionKey();
return owner != null ? owner : Thread.currentThread();
}
}