/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq.ra;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import javax.jms.JMSException;
import javax.jms.ServerSession;
import javax.jms.ServerSessionPool;
import javax.jms.Session;
import javax.resource.spi.UnavailableException;
import javax.resource.spi.endpoint.MessageEndpoint;
import org.apache.activemq.ActiveMQQueueSession;
import org.apache.activemq.ActiveMQSession;
import org.apache.activemq.ActiveMQTopicSession;
import org.apache.activemq.command.MessageDispatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* $Date$
*/
public class ServerSessionPoolImpl implements ServerSessionPool {
private static final Logger LOG = LoggerFactory.getLogger(ServerSessionPoolImpl.class);
private final ActiveMQEndpointWorker activeMQAsfEndpointWorker;
private final int maxSessions;
private final List<ServerSessionImpl> idleSessions = new ArrayList<ServerSessionImpl>();
private final List<ServerSessionImpl> activeSessions = new ArrayList<ServerSessionImpl>();
private final Lock sessionLock = new ReentrantLock();
private final AtomicBoolean closing = new AtomicBoolean(false);
public ServerSessionPoolImpl(ActiveMQEndpointWorker activeMQAsfEndpointWorker, int maxSessions) {
this.activeMQAsfEndpointWorker = activeMQAsfEndpointWorker;
this.maxSessions = maxSessions;
}
private ServerSessionImpl createServerSessionImpl() throws JMSException {
MessageActivationSpec activationSpec = activeMQAsfEndpointWorker.endpointActivationKey.getActivationSpec();
int acknowledge = (activeMQAsfEndpointWorker.transacted) ? Session.SESSION_TRANSACTED : activationSpec.getAcknowledgeModeForSession();
final ActiveMQSession session = (ActiveMQSession)activeMQAsfEndpointWorker.getConnection().createSession(activeMQAsfEndpointWorker.transacted, acknowledge);
MessageEndpoint endpoint;
try {
int batchSize = 0;
if (activationSpec.getEnableBatchBooleanValue()) {
batchSize = activationSpec.getMaxMessagesPerBatchIntValue();
}
if (activationSpec.isUseRAManagedTransactionEnabled()) {
// The RA will manage the transaction commit.
endpoint = createEndpoint(null);
return new ServerSessionImpl(this, (ActiveMQSession)session, activeMQAsfEndpointWorker.workManager, endpoint, true, batchSize);
} else {
// Give the container an object to manage to transaction with.
endpoint = createEndpoint(new LocalAndXATransaction(session.getTransactionContext()));
return new ServerSessionImpl(this, (ActiveMQSession)session, activeMQAsfEndpointWorker.workManager, endpoint, false, batchSize);
}
} catch (UnavailableException e) {
// The container could be limiting us on the number of endpoints
// that are being created.
if (LOG.isDebugEnabled()) {
LOG.debug("Could not create an endpoint.", e);
}
session.close();
return null;
}
}
private MessageEndpoint createEndpoint(LocalAndXATransaction txResourceProxy) throws UnavailableException {
MessageEndpoint endpoint;
endpoint = activeMQAsfEndpointWorker.endpointFactory.createEndpoint(txResourceProxy);
MessageEndpointProxy endpointProxy = new MessageEndpointProxy(endpoint);
return endpointProxy;
}
/**
*/
public ServerSession getServerSession() throws JMSException {
if (LOG.isDebugEnabled()) {
LOG.debug("ServerSession requested.");
}
if (closing.get()) {
throw new JMSException("Session Pool Shutting Down.");
}
ServerSessionImpl ss = null;
sessionLock.lock();
try {
ss = getExistingServerSession(false);
} finally {
sessionLock.unlock();
}
if (ss != null) {
return ss;
}
ss = createServerSessionImpl();
sessionLock.lock();
try {
// We may not be able to create a session due to the container
// restricting us.
if (ss == null) {
if (activeSessions.isEmpty() && idleSessions.isEmpty()) {
throw new JMSException("Endpoint factory did not allow creation of any endpoints.");
}
ss = getExistingServerSession(true);
} else {
activeSessions.add(ss);
}
} finally {
sessionLock.unlock();
}
if (LOG.isDebugEnabled()) {
LOG.debug("Created a new session: " + ss);
}
return ss;
}
/**
* Must be called with sessionLock held.
* Returns an idle session if one exists or an active session if no more
* sessions can be created. Sessions can not be created if force is true
* or activeSessions >= maxSessions.
* @param force do not check activeSessions >= maxSessions, return an active connection anyway.
* @return an already existing session.
*/
private ServerSessionImpl getExistingServerSession(boolean force) {
ServerSessionImpl ss = null;
if (idleSessions.size() > 0) {
ss = idleSessions.remove(idleSessions.size() - 1);
}
if (ss != null) {
activeSessions.add(ss);
if (LOG.isDebugEnabled()) {
LOG.debug("Using idle session: " + ss);
}
} else if (force || activeSessions.size() >= maxSessions) {
// If we are at the upper limit
// then reuse the already created sessions..
// This is going to queue up messages into a session for
// processing.
ss = getExistingActiveServerSession();
}
return ss;
}
/**
* Must be called with sessionLock held.
* Returns the first session from activeSessions, shifting it to last.
* @return session
*/
private ServerSessionImpl getExistingActiveServerSession() {
ServerSessionImpl ss = null;
if (!activeSessions.isEmpty()) {
if (activeSessions.size() > 1) {
// round robin
ss = activeSessions.remove(0);
activeSessions.add(ss);
} else {
ss = activeSessions.get(0);
}
}
if (LOG.isDebugEnabled()) {
LOG.debug("Reusing an active session: " + ss);
}
return ss;
}
public void returnToPool(ServerSessionImpl ss) {
sessionLock.lock();
activeSessions.remove(ss);
try {
// make sure we only return non-stale sessions to the pool
if ( ss.isStale() ) {
if ( LOG.isDebugEnabled() ) {
LOG.debug("Discarding stale ServerSession to be returned to pool: " + ss);
}
ss.close();
} else {
if (LOG.isDebugEnabled()) {
LOG.debug("ServerSession returned to pool: " + ss);
}
idleSessions.add(ss);
}
} finally {
sessionLock.unlock();
}
synchronized (closing) {
closing.notify();
}
}
public void removeFromPool(ServerSessionImpl ss) {
sessionLock.lock();
try {
activeSessions.remove(ss);
} finally {
sessionLock.unlock();
}
try {
ActiveMQSession session = (ActiveMQSession)ss.getSession();
List l = session.getUnconsumedMessages();
for (Iterator i = l.iterator(); i.hasNext();) {
dispatchToSession((MessageDispatch)i.next());
}
} catch (Throwable t) {
LOG.error("Error redispatching unconsumed messages from stale session", t);
}
ss.close();
synchronized (closing) {
closing.notify();
}
}
/**
* @param messageDispatch
* the message to dispatch
* @throws JMSException
*/
private void dispatchToSession(MessageDispatch messageDispatch)
throws JMSException {
ServerSession serverSession = getServerSession();
Session s = serverSession.getSession();
ActiveMQSession session = null;
if (s instanceof ActiveMQSession) {
session = (ActiveMQSession) s;
} else if (s instanceof ActiveMQQueueSession) {
session = (ActiveMQSession) s;
} else if (s instanceof ActiveMQTopicSession) {
session = (ActiveMQSession) s;
} else {
activeMQAsfEndpointWorker.getConnection()
.onAsyncException(new JMSException(
"Session pool provided an invalid session type: "
+ s.getClass()));
}
session.dispatch(messageDispatch);
serverSession.start();
}
public void close() {
closing.set(true);
int activeCount = closeIdleSessions();
// we may have to wait erroneously 250ms if an
// active session is removed during our wait and we
// are not notified
while (activeCount > 0) {
if (LOG.isDebugEnabled()) {
LOG.debug("Active Sessions = " + activeCount);
}
try {
synchronized (closing) {
closing.wait(250);
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
return;
}
activeCount = closeIdleSessions();
}
}
protected int closeIdleSessions() {
sessionLock.lock();
try {
for (ServerSessionImpl ss : idleSessions) {
ss.close();
}
idleSessions.clear();
return activeSessions.size();
} finally {
sessionLock.unlock();
}
}
/**
* @return Returns the closing.
*/
public boolean isClosing() {
return closing.get();
}
/**
* @param closing The closing to set.
*/
public void setClosing(boolean closing) {
this.closing.set(closing);
}
}