/*
* JBoss, Home of Professional Open Source.
* Copyright 2010, Red Hat Middleware LLC, 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
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.jca.core.connectionmanager.pool.mcp;
import org.jboss.jca.common.JBossResourceException;
import org.jboss.jca.core.connectionmanager.listener.ConnectionListener;
import org.jboss.jca.core.connectionmanager.listener.ConnectionListenerFactory;
import org.jboss.jca.core.connectionmanager.listener.ConnectionState;
import org.jboss.jca.core.connectionmanager.pool.SubPoolContext;
import org.jboss.jca.core.connectionmanager.pool.api.Pool;
import org.jboss.jca.core.connectionmanager.pool.api.PoolConfiguration;
import org.jboss.jca.core.connectionmanager.pool.idle.IdleRemover;
import org.jboss.jca.core.connectionmanager.pool.validator.ConnectionValidator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import javax.resource.ResourceException;
import javax.resource.spi.ConnectionRequestInfo;
import javax.resource.spi.ManagedConnection;
import javax.resource.spi.ManagedConnectionFactory;
import javax.resource.spi.RetryableUnavailableException;
import javax.resource.spi.ValidatingManagedConnectionFactory;
import javax.security.auth.Subject;
import org.jboss.logging.Logger;
import org.jboss.util.UnreachableStatementException;
/**
* The internal pool implementation
*
* @author <a href="mailto:d_jencks@users.sourceforge.net">David Jencks</a>
* @author <a href="mailto:adrian@jboss.org">Adrian Brock</a>
* @author <a href="mailto:weston.price@jboss.com">Weston Price</a>
* @author <a href="mailto:jesper.pedersen@jboss.org">Jesper Pedersen</a>
* @version $Revision: 107890 $
*/
public class SemaphoreArrayListManagedConnectionPool implements ManagedConnectionPool
{
/** The log */
private Logger log;
/** Whether trace is enabled */
private boolean trace;
/** The managed connection factory */
private ManagedConnectionFactory mcf;
/** The connection listener factory */
private ConnectionListenerFactory clf;
/** The default subject */
private Subject defaultSubject;
/** The default connection request information */
private ConnectionRequestInfo defaultCri;
/** The pool configuration */
private PoolConfiguration poolConfiguration;
/** The pool */
private Pool pool;
/**
* Copy of the maximum size from the pooling parameters.
* Dynamic changes to this value are not compatible with
* the semaphore which cannot change be dynamically changed.
*/
private int maxSize;
/** The available connection event listeners */
private ArrayList<ConnectionListener> cls;
/** The permits used to control who can checkout a connection */
private Semaphore permits;
/** The map of connection listeners which has a permit */
private ConcurrentMap<ConnectionListener, ConnectionListener> clPermits =
new ConcurrentHashMap<ConnectionListener, ConnectionListener>();
/** The sub pool */
private SubPoolContext subPool;
/** The checked out connections */
private HashSet<ConnectionListener> checkedOut = new HashSet<ConnectionListener>();
/** Whether the pool has been started */
private AtomicBoolean started = new AtomicBoolean(false);
/** Whether the pool has been shutdown */
private AtomicBoolean shutdown = new AtomicBoolean(false);
/** the max connections ever checked out **/
private volatile int maxUsedConnections = 0;
/**
* Constructor
*/
public SemaphoreArrayListManagedConnectionPool()
{
}
/**
* {@inheritDoc}
*/
public void initialize(ManagedConnectionFactory mcf, ConnectionListenerFactory clf, Subject subject,
ConnectionRequestInfo cri, PoolConfiguration pc, Pool p, SubPoolContext spc,
Logger log)
{
this.mcf = mcf;
this.clf = clf;
this.defaultSubject = subject;
this.defaultCri = cri;
this.poolConfiguration = pc;
this.maxSize = pc.getMaxSize();
this.pool = p;
this.subPool = spc;
this.log = log;
this.trace = log.isTraceEnabled();
this.cls = new ArrayList<ConnectionListener>(this.maxSize);
this.permits = new Semaphore(this.maxSize, true);
if (pc.isPrefill())
{
PoolFiller.fillPool(this);
}
reenable();
}
/**
* {@inheritDoc}
*/
public SubPoolContext getSubPool()
{
return subPool;
}
/**
* {@inheritDoc}
*/
public boolean isRunning()
{
return !shutdown.get();
}
/**
* {@inheritDoc}
*/
public boolean isEmpty()
{
synchronized (cls)
{
return cls.size() == 0 && checkedOut.size() == 0;
}
}
/**
* {@inheritDoc}
*/
public void reenable()
{
if (poolConfiguration.getIdleTimeout() > 0L)
{
//Register removal support
IdleRemover.registerPool(this, poolConfiguration.getIdleTimeout());
}
if (poolConfiguration.isBackgroundValidation() && poolConfiguration.getBackgroundValidationInterval() > 0)
{
log.debug("Registering for background validation at interval " +
poolConfiguration.getBackgroundValidationInterval());
//Register validation
ConnectionValidator.registerPool(this, poolConfiguration.getBackgroundValidationInterval());
}
shutdown.set(false);
}
/**
* {@inheritDoc}
*/
public ConnectionListener getConnection(Subject subject, ConnectionRequestInfo cri) throws ResourceException
{
subject = (subject == null) ? defaultSubject : subject;
cri = (cri == null) ? defaultCri : cri;
long startWait = System.currentTimeMillis();
try
{
if (permits.tryAcquire(poolConfiguration.getBlockingTimeout(), TimeUnit.MILLISECONDS))
{
//We have a permit to get a connection. Is there one in the pool already?
ConnectionListener cl = null;
do
{
synchronized (cls)
{
if (shutdown.get())
{
permits.release();
throw new RetryableUnavailableException("The pool has been shutdown");
}
int clsSize = cls.size();
if (clsSize > 0)
{
cl = cls.remove(clsSize - 1);
checkedOut.add(cl);
int size = maxSize - permits.availablePermits();
if (size > maxUsedConnections)
maxUsedConnections = size;
}
}
if (cl != null)
{
//Yes, we retrieved a ManagedConnection from the pool. Does it match?
try
{
Object matchedMC = mcf.matchManagedConnections(Collections.singleton(cl.getManagedConnection()),
subject, cri);
if (matchedMC != null)
{
if (trace)
log.trace("supplying ManagedConnection from pool: " + cl);
clPermits.put(cl, cl);
return cl;
}
// Match did not succeed but no exception was thrown.
// Either we have the matching strategy wrong or the
// connection died while being checked. We need to
// distinguish these cases, but for now we always
// destroy the connection.
log.warn("Destroying connection that could not be successfully matched: " + cl);
synchronized (cls)
{
checkedOut.remove(cl);
}
doDestroy(cl);
cl = null;
}
catch (Throwable t)
{
log.warn("Throwable while trying to match ManagedConnection, destroying connection: " + cl, t);
synchronized (cls)
{
checkedOut.remove(cl);
}
doDestroy(cl);
cl = null;
}
// We made it here, something went wrong and we should validate
// if we should continue attempting to acquire a connection
if (poolConfiguration.isUseFastFail())
{
log.trace("Fast failing for connection attempt. No more attempts will be made to " +
"acquire connection from pool and a new connection will be created immeadiately");
break;
}
}
}
while (cls.size() > 0);
// OK, we couldnt find a working connection from the pool. Make a new one.
try
{
// No, the pool was empty, so we have to make a new one.
cl = createConnectionEventListener(subject, cri);
synchronized (cls)
{
checkedOut.add(cl);
int size = maxSize - permits.availablePermits();
if (size > maxUsedConnections)
maxUsedConnections = size;
}
if (!started.getAndSet(true))
{
if (poolConfiguration.getMinSize() > 0)
PoolFiller.fillPool(this);
}
if (trace)
log.trace("supplying new ManagedConnection: " + cl);
clPermits.put(cl, cl);
return cl;
}
catch (Throwable t)
{
log.warn("Throwable while attempting to get a new connection: " + cl, t);
// Return permit and rethrow
synchronized (cls)
{
checkedOut.remove(cl);
}
permits.release();
JBossResourceException.rethrowAsResourceException("Unexpected throwable while trying to " +
"create a connection: " + cl, t);
throw new UnreachableStatementException();
}
}
else
{
// We timed out
throw new ResourceException("No ManagedConnections available within configured blocking timeout ( "
+ poolConfiguration.getBlockingTimeout() + " [ms] )");
}
}
catch (InterruptedException ie)
{
long end = System.currentTimeMillis() - startWait;
throw new ResourceException("Interrupted while requesting permit! Waited " + end + " ms");
}
}
/**
* {@inheritDoc}
*/
public void returnConnection(ConnectionListener cl, boolean kill)
{
synchronized (cls)
{
if (cl.getState() == ConnectionState.DESTROYED)
{
if (trace)
log.trace("ManagedConnection is being returned after it was destroyed" + cl);
if (clPermits.containsKey(cl))
{
clPermits.remove(cl);
permits.release();
}
return;
}
}
if (trace)
log.trace("putting ManagedConnection back into pool kill=" + kill + " cl=" + cl);
try
{
cl.getManagedConnection().cleanup();
}
catch (ResourceException re)
{
log.warn("ResourceException cleaning up ManagedConnection: " + cl, re);
kill = true;
}
synchronized (cls)
{
// We need to destroy this one
if (cl.getState() == ConnectionState.DESTROY || cl.getState() == ConnectionState.DESTROYED)
kill = true;
checkedOut.remove(cl);
// This is really an error
if (!kill && cls.size() >= poolConfiguration.getMaxSize())
{
log.warn("Destroying returned connection, maximum pool size exceeded " + cl);
kill = true;
}
// If we are destroying, check the connection is not in the pool
if (kill)
{
// Adrian Brock: A resource adapter can asynchronously notify us that
// a connection error occurred.
// This could happen while the connection is not checked out.
// e.g. JMS can do this via an ExceptionListener on the connection.
// I have twice had to reinstate this line of code, PLEASE DO NOT REMOVE IT!
cls.remove(cl);
}
// return to the pool
else
{
cl.used();
if (!cls.contains(cl))
{
cls.add(cl);
}
else
{
log.warn("Attempt to return connection twice (ignored): " + cl, new Throwable("STACKTRACE"));
}
}
if (clPermits.containsKey(cl))
{
clPermits.remove(cl);
permits.release();
}
}
if (kill)
{
if (trace)
log.trace("Destroying returned connection " + cl);
doDestroy(cl);
}
}
/**
* {@inheritDoc}
*/
public void flush()
{
ArrayList<ConnectionListener> destroy = null;
synchronized (cls)
{
if (trace)
log.trace("Flushing pool checkedOut=" + checkedOut + " inPool=" + cls);
// Mark checked out connections as requiring destruction
for (Iterator<ConnectionListener> i = checkedOut.iterator(); i.hasNext();)
{
ConnectionListener cl = i.next();
if (trace)
log.trace("Flush marking checked out connection for destruction " + cl);
cl.setState(ConnectionState.DESTROY);
}
// Destroy connections in the pool
while (cls.size() > 0)
{
ConnectionListener cl = cls.remove(0);
if (destroy == null)
destroy = new ArrayList<ConnectionListener>(1);
destroy.add(cl);
}
}
// We need to destroy some connections
if (destroy != null)
{
for (int i = 0; i < destroy.size(); ++i)
{
ConnectionListener cl = destroy.get(i);
if (trace)
log.trace("Destroying flushed connection " + cl);
doDestroy(cl);
}
// We destroyed something, check the minimum.
if (!shutdown.get() && poolConfiguration.getMinSize() > 0)
PoolFiller.fillPool(this);
}
}
/**
* {@inheritDoc}
*/
public void removeIdleConnections()
{
ArrayList<ConnectionListener> destroy = null;
long timeout = System.currentTimeMillis() - poolConfiguration.getIdleTimeout();
while (true)
{
synchronized (cls)
{
// Nothing left to destroy
if (cls.size() == 0)
break;
// Check the first in the list
ConnectionListener cl = cls.get(0);
if (cl.isTimedOut(timeout) && shouldRemove())
{
// We need to destroy this one
cls.remove(0);
if (destroy == null)
destroy = new ArrayList<ConnectionListener>(1);
destroy.add(cl);
}
else
{
// They were inserted chronologically, so if this one isn't timed out, following ones won't be either.
break;
}
}
}
// We found some connections to destroy
if (destroy != null)
{
for (int i = 0; i < destroy.size(); ++i)
{
ConnectionListener cl = destroy.get(i);
if (trace)
log.trace("Destroying timedout connection " + cl);
doDestroy(cl);
}
// We destroyed something, check the minimum.
if (!shutdown.get() && poolConfiguration.getMinSize() > 0)
PoolFiller.fillPool(this);
// Empty sub-pool
if (pool != null)
pool.emptySubPool(this);
}
}
/**
* {@inheritDoc}
*/
public void shutdown()
{
shutdown.set(true);
IdleRemover.unregisterPool(this);
ConnectionValidator.unregisterPool(this);
flush();
}
/**
* {@inheritDoc}
*/
public void fillToMin()
{
while (true)
{
// Get a permit - avoids a race when the pool is nearly full
// Also avoids unnessary fill checking when all connections are checked out
try
{
if (permits.tryAcquire(poolConfiguration.getBlockingTimeout(), TimeUnit.MILLISECONDS))
{
try
{
if (shutdown.get())
return;
// We already have enough connections
if (poolConfiguration.getMinSize() - (cls.size() + checkedOut.size()) <= 0)
return;
// Create a connection to fill the pool
try
{
ConnectionListener cl = createConnectionEventListener(defaultSubject, defaultCri);
synchronized (cls)
{
if (trace)
log.trace("Filling pool cl=" + cl);
cls.add(cl);
}
}
catch (ResourceException re)
{
log.warn("Unable to fill pool ", re);
return;
}
}
finally
{
permits.release();
}
}
}
catch (InterruptedException ignored)
{
log.trace("Interrupted while requesting permit in fillToMin");
}
}
}
/**
* Create a connection event listener
*
* @param subject the subject
* @param cri the connection request information
* @return the new listener
* @throws ResourceException for any error
*/
private ConnectionListener createConnectionEventListener(Subject subject, ConnectionRequestInfo cri)
throws ResourceException
{
ManagedConnection mc = mcf.createManagedConnection(subject, cri);
try
{
return clf.createConnectionListener(mc, this);
}
catch (ResourceException re)
{
mc.destroy();
throw re;
}
}
/**
* Destroy a connection
*
* @param cl the connection to destroy
*/
private void doDestroy(ConnectionListener cl)
{
if (cl.getState() == ConnectionState.DESTROYED)
{
if (trace)
log.trace("ManagedConnection is already destroyed " + cl);
return;
}
cl.setState(ConnectionState.DESTROYED);
try
{
cl.getManagedConnection().destroy();
}
catch (Throwable t)
{
log.debug("Exception destroying ManagedConnection " + cl, t);
}
}
/**
* Should any connections be removed from the pool
* @return True if connections should be removed; otherwise false
*/
private boolean shouldRemove()
{
boolean remove = true;
if (poolConfiguration.isStrictMin())
{
remove = cls.size() > poolConfiguration.getMinSize();
if (trace)
log.trace("StrictMin is active. Current connection will be removed is " + remove);
}
return remove;
}
/**
* {@inheritDoc}
*/
public void validateConnections() throws Exception
{
if (trace)
log.trace("Attempting to validate connections for pool " + this);
if (permits.tryAcquire(poolConfiguration.getBlockingTimeout(), TimeUnit.MILLISECONDS))
{
boolean anyDestroyed = false;
try
{
while (true)
{
ConnectionListener cl = null;
boolean destroyed = false;
synchronized (cls)
{
if (cls.size() == 0)
{
break;
}
cl = removeForFrequencyCheck();
}
if (cl == null)
{
break;
}
try
{
Set candidateSet = Collections.singleton(cl.getManagedConnection());
if (mcf instanceof ValidatingManagedConnectionFactory)
{
ValidatingManagedConnectionFactory vcf = (ValidatingManagedConnectionFactory) mcf;
candidateSet = vcf.getInvalidConnections(candidateSet);
if (candidateSet != null && candidateSet.size() > 0)
{
if (cl.getState() != ConnectionState.DESTROY)
{
doDestroy(cl);
destroyed = true;
anyDestroyed = true;
}
}
}
else
{
log.warn("Warning: background validation was specified with a non " +
"compliant ManagedConnectionFactory interface.");
}
}
finally
{
if (!destroyed)
{
synchronized (cls)
{
returnForFrequencyCheck(cl);
}
}
}
}
}
finally
{
permits.release();
if (anyDestroyed && !shutdown.get() && poolConfiguration.getMinSize() > 0)
{
PoolFiller.fillPool(this);
}
}
}
}
/**
* Returns the connection listener that should be removed due to background validation
* @return The listener; otherwise null if none should be removed
*/
private ConnectionListener removeForFrequencyCheck()
{
log.debug("Checking for connection within frequency");
ConnectionListener cl = null;
for (Iterator<ConnectionListener> iter = cls.iterator(); iter.hasNext();)
{
cl = iter.next();
long lastCheck = cl.getLastValidatedTime();
if ((System.currentTimeMillis() - lastCheck) >= poolConfiguration.getBackgroundValidationInterval())
{
cls.remove(cl);
break;
}
else
{
cl = null;
}
}
return cl;
}
/**
* Return a connection listener to the pool and update its validation timestamp
* @param cl The listener
*/
private void returnForFrequencyCheck(ConnectionListener cl)
{
log.debug("Returning for connection within frequency");
cl.setLastValidatedTime(System.currentTimeMillis());
cls.add(cl);
}
}