/*
* JBoss, Home of Professional Open Source.
* Copyright 2014, Red Hat, Inc., and individual contributors
* as indicated by the @author tags. See the copyright.txt file in the
* distribution for a full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* 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,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 2110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.as.ejb3.component.interceptors;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import org.jboss.as.ejb3.logging.EjbLogger;
import org.jboss.invocation.Interceptor;
import org.jboss.invocation.InterceptorContext;
import org.jboss.invocation.InterceptorFactory;
import org.jboss.invocation.InterceptorFactoryContext;
/**
* A per component interceptor that allows the EJB to shutdown gracefully.
*
* @author Stuart Douglas
*/
public class ShutDownInterceptorFactory implements InterceptorFactory {
private static final int SHUTDOWN_FLAG = 1 << 31;
private static final int INVERSE_SHUTDOWN_FLAG = ~SHUTDOWN_FLAG;
private static final AtomicIntegerFieldUpdater<ShutDownInterceptorFactory> updater = AtomicIntegerFieldUpdater.newUpdater(ShutDownInterceptorFactory.class, "invocationCount");
@SuppressWarnings("unused")
private volatile int invocationCount;
private final Object lock = new Object();
private Interceptor interceptor = new Interceptor() {
@Override
public Object processInvocation(InterceptorContext context) throws Exception {
int value;
int oldValue;
do {
oldValue = invocationCount;
if ((oldValue & SHUTDOWN_FLAG) != 0) {
throw EjbLogger.ROOT_LOGGER.componentIsShuttingDown();
}
value = oldValue + 1;
} while (!updater.compareAndSet(ShutDownInterceptorFactory.this, oldValue, value));
try {
return context.proceed();
} finally {
do {
oldValue = invocationCount;
boolean shutDown = (oldValue & SHUTDOWN_FLAG) != 0;
int oldCount = oldValue & INVERSE_SHUTDOWN_FLAG;
value = oldCount - 1;
if(shutDown) {
value = value | SHUTDOWN_FLAG;
}
} while (!updater.compareAndSet(ShutDownInterceptorFactory.this, oldValue, value));
//if the count is zero and the component is shutting down
if (value == SHUTDOWN_FLAG) {
synchronized (lock) {
lock.notifyAll();
}
}
}
}
};
@Override
public Interceptor create(InterceptorFactoryContext context) {
return interceptor;
}
/**
* Upon calling this method the EJB will be set to a shutdown state, and no further invocations will be allowed.
* It will then wait for all active invocation to finish and then return.
*/
public void shutdown() {
int value;
int oldValue;
//set the shutdown bit
do {
oldValue = invocationCount;
value = SHUTDOWN_FLAG | oldValue;
//the component has already been shutdown
if (oldValue == value) {
return;
}
} while (!updater.compareAndSet(this, oldValue, value));
synchronized (lock) {
value = invocationCount;
while (value != SHUTDOWN_FLAG) {
try {
lock.wait();
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
value = invocationCount;
if((value & SHUTDOWN_FLAG) == 0) {
return; //component has been restarted
}
}
}
}
public void start() {
int value;
int oldValue;
//set the shutdown bit
do {
oldValue = invocationCount;
value = INVERSE_SHUTDOWN_FLAG & oldValue;
//the component has already been started
if (oldValue == value) {
return;
}
} while (!updater.compareAndSet(this, oldValue, value));
synchronized (lock) {
lock.notifyAll();
}
}
}