/*
* JBoss, Home of Professional Open Source.
* Copyright 2006, 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.resource.connectionmanager;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
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.ValidatingManagedConnectionFactory;
import javax.security.auth.Subject;
import org.jboss.logging.Logger;
import org.jboss.resource.JBossResourceException;
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: 102148 $
*/
public class InternalManagedConnectionPool implements IdleConnectionRemovalSupport
{
/** The managed connection factory */
private final ManagedConnectionFactory mcf;
/** The connection listener factory */
private final ConnectionListenerFactory clf;
/** The default subject */
private final Subject defaultSubject;
/** The default connection request information */
private final ConnectionRequestInfo defaultCri;
/** The pooling parameters */
private final PoolParams poolParams;
/** The JBoss managed connection pool */
private final JBossManagedConnectionPool jmcp;
/** 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 cls;
/** The permits used to control who can checkout a connection */
private final Semaphore permits;
/** The log */
private final Logger log;
/** Whether trace is enabled */
private final boolean trace;
/** Stats */
private final Counter connectionCounter = new Counter();
/** The checked out connections */
private final HashSet checkedOut = new HashSet();
/** Whether the pool has been started */
private boolean started = false;
/** Whether the pool has been shutdown */
private AtomicBoolean shutdown = new AtomicBoolean(false);
/** the max connections ever checked out **/
private volatile int maxUsedConnections = 0;
/**
* Create a new internal pool
*
* @param mcf the managed connection factory
* @param subject the subject
* @param cri the connection request information
* @param poolParams the pooling parameters
* @param log the log
*/
protected InternalManagedConnectionPool(ManagedConnectionFactory mcf, ConnectionListenerFactory clf, Subject subject,
ConnectionRequestInfo cri, PoolParams poolParams, JBossManagedConnectionPool jmcp,
Logger log)
{
this.mcf = mcf;
this.clf = clf;
this.defaultSubject = subject;
this.defaultCri = cri;
this.poolParams = poolParams;
this.maxSize = poolParams.maxSize;
this.jmcp = jmcp;
this.log = log;
this.trace = log.isTraceEnabled();
this.cls = new ArrayList(this.maxSize);
this.permits = new Semaphore(this.maxSize, true);
if (poolParams.prefill)
{
PoolFiller.fillPool(this);
}
}
/**
* Initialize the pool
*/
protected void initialize()
{
if (poolParams.idleTimeout != 0)
IdleRemover.registerPool(this, poolParams.idleTimeout);
if (poolParams.backgroundInterval > 0)
{
log.debug("Registering for background validation at interval " + poolParams.backgroundInterval);
ConnectionValidator.registerPool(this, poolParams.backgroundInterval);
}
shutdown.set(false);
}
protected boolean isRunning()
{
return !shutdown.get();
}
public long getAvailableConnections()
{
return permits.availablePermits();
}
public int getMaxConnectionsInUseCount()
{
return maxUsedConnections;
}
public int getConnectionInUseCount()
{
return checkedOut.size();
}
/**
* todo distinguish between connection dying while match called
* and bad match strategy. In latter case we should put it back in
* the pool.
*/
public ConnectionListener getConnection(Subject subject, ConnectionRequestInfo cri) throws ResourceException
{
subject = (subject == null) ? defaultSubject : subject;
cri = (cri == null) ? defaultCri : cri;
long startWait = System.currentTimeMillis();
try
{
connectionCounter.updateBlockTime(System.currentTimeMillis() - startWait);
if (permits.tryAcquire(poolParams.blockingTimeout, TimeUnit.MILLISECONDS))
{
long poolBlockTime = System.currentTimeMillis() - startWait ;
connectionCounter.updateBlockTime(poolBlockTime);
//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 RetryableResourceException("The pool has been shutdown");
}
int clsSize = cls.size();
if (clsSize > 0)
{
cl = (ConnectionListener) cls.remove(clsSize - 1);
checkedOut.add(cl);
int size = (int) (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);
cl.grantPermit(true);
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(poolParams.useFastFail)
{
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);//end of do loop
//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 = (int) (maxSize - permits.availablePermits());
if (size > maxUsedConnections)
maxUsedConnections = size;
}
//lack of synch on "started" probably ok, if 2 reads occur we will just
//run fillPool twice, no harm done.
if (started == false)
{
started = true;
if (poolParams.minSize > 0)
PoolFiller.fillPool(this);
}
if (trace)
log.trace("supplying new ManagedConnection: " + cl);
cl.grantPermit(true);
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 ( "
+ poolParams.blockingTimeout + " [ms] )");
}
}
catch (InterruptedException ie)
{
long end = System.currentTimeMillis() - startWait;
connectionCounter.updateBlockTime(end);
throw new ResourceException("Interrupted while requesting permit! Waited " + end + " ms");
}
}
public void returnConnection(ConnectionListener cl, boolean kill)
{
synchronized (cls)
{
if (cl.getState() == ConnectionListener.DESTROYED)
{
if (trace)
log.trace("ManagedConnection is being returned after it was destroyed" + cl);
if (cl.hasPermit())
{
// release semaphore
cl.grantPermit(false);
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() == ConnectionListener.DESTROY || cl.getState() == ConnectionListener.DESTROYED)
kill = true;
checkedOut.remove(cl);
// This is really an error
if (kill == false && cls.size() >= poolParams.maxSize)
{
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) == false)
cls.add(cl);
else
log.warn("Attempt to return connection twice (ignored): " + cl, new Throwable("STACKTRACE"));
}
if (cl.hasPermit())
{
// release semaphore
cl.grantPermit(false);
permits.release();
}
}
if (kill)
{
if (trace)
log.trace("Destroying returned connection " + cl);
doDestroy(cl);
}
}
public void flush()
{
ArrayList destroy = null;
synchronized (cls)
{
if (trace)
log.trace("Flushing pool checkedOut=" + checkedOut + " inPool=" + cls);
// Mark checked out connections as requiring destruction
for (Iterator i = checkedOut.iterator(); i.hasNext();)
{
ConnectionListener cl = (ConnectionListener) i.next();
if (trace)
log.trace("Flush marking checked out connection for destruction " + cl);
cl.setState(ConnectionListener.DESTROY);
}
// Destroy connections in the pool
while (cls.size() > 0)
{
ConnectionListener cl = (ConnectionListener) cls.remove(0);
if (destroy == null)
destroy = new ArrayList();
destroy.add(cl);
}
}
// We need to destroy some connections
if (destroy != null)
{
for (int i = 0; i < destroy.size(); ++i)
{
ConnectionListener cl = (ConnectionListener) destroy.get(i);
if (trace)
log.trace("Destroying flushed connection " + cl);
doDestroy(cl);
}
// We destroyed something, check the minimum.
if (shutdown.get() == false && poolParams.minSize > 0)
PoolFiller.fillPool(this);
}
}
public void removeIdleConnections()
{
ArrayList destroy = null;
long timeout = System.currentTimeMillis() - poolParams.idleTimeout;
while (true)
{
synchronized (cls)
{
// Nothing left to destroy
if (cls.size() == 0)
break;
// Check the first in the list
ConnectionListener cl = (ConnectionListener) cls.get(0);
if (cl.isTimedOut(timeout) && shouldRemove())
{
connectionCounter.incTimedOut();
// We need to destroy this one
cls.remove(0);
if (destroy == null)
destroy = new ArrayList();
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 = (ConnectionListener) destroy.get(i);
if (trace)
log.trace("Destroying timedout connection " + cl);
doDestroy(cl);
}
// We destroyed something, check the minimum.
if (shutdown.get() == false && poolParams.minSize > 0)
PoolFiller.fillPool(this);
// Empty sub-pool
if (jmcp != null)
jmcp.getPoolingStrategy().emptySubPool(this);
}
}
/**
* For testing
*/
public void shutdownWithoutClear()
{
IdleRemover.unregisterPool(this);
IdleRemover.waitForBackgroundThread();
ConnectionValidator.unRegisterPool(this);
ConnectionValidator.waitForBackgroundThread();
fillToMin();
shutdown.set(true);
}
public void shutdown()
{
shutdown.set(true);
IdleRemover.unregisterPool(this);
ConnectionValidator.unRegisterPool(this);
flush();
}
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(poolParams.blockingTimeout, TimeUnit.MILLISECONDS))
{
try
{
if (shutdown.get())
return;
// We already have enough connections
if (getMinSize() - connectionCounter.getGuaranteedCount() <= 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");
}
}
}
public int getConnectionCount()
{
return connectionCounter.getCount();
}
public long getTotalBlockTime()
{
return connectionCounter.getTotalBlockTime();
}
public int getTimedOut()
{
return connectionCounter.getTimedOut();
}
public long getAverageBlockTime()
{
return connectionCounter.getTotalBlockTime() / getConnectionCreatedCount();
}
public long getMaxWaitTime()
{
return connectionCounter.getMaxWaitTime();
}
public int getConnectionCreatedCount()
{
return connectionCounter.getCreatedCount();
}
public int getConnectionDestroyedCount()
{
return connectionCounter.getDestroyedCount();
}
Set getConnectionListeners()
{
synchronized (cls)
{
Set result = new HashSet();
result.addAll(cls);
result.addAll(checkedOut);
return result;
}
}
boolean isEmpty()
{
synchronized (cls)
{
return cls.size() == 0;
}
}
/**
* 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);
connectionCounter.inc();
try
{
return clf.createConnectionListener(mc, this);
}
catch (ResourceException re)
{
connectionCounter.dec();
mc.destroy();
throw re;
}
}
/**
* Destroy a connection
*
* @param cl the connection to destroy
*/
private void doDestroy(ConnectionListener cl)
{
if (cl.getState() == ConnectionListener.DESTROYED)
{
log.trace("ManagedConnection is already destroyed " + cl);
return;
}
connectionCounter.dec();
cl.setState(ConnectionListener.DESTROYED);
try
{
cl.getManagedConnection().destroy();
}
catch (Throwable t)
{
log.debug("Exception destroying ManagedConnection " + cl, t);
}
}
private boolean shouldRemove()
{
boolean remove = true;
if(poolParams.stictMin)
{
remove = cls.size() > poolParams.minSize;
log.trace("StrictMin is active. Current connection will be removed is " + remove);
}
return remove;
}
public void validateConnections() throws Exception
{
if (trace)
log.trace("Attempting to validate connections for pool " + this);
if (permits.tryAcquire(poolParams.blockingTimeout, 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() != ConnectionListener.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() == false && poolParams.minSize > 0)
{
PoolFiller.fillPool(this);
}
}
}
}
private ConnectionListener removeForFrequencyCheck()
{
log.debug("Checking for connection within frequency");
ConnectionListener cl = null;
for (Iterator iter = cls.iterator(); iter.hasNext();)
{
cl = (ConnectionListener) iter.next();
long lastCheck = cl.getLastValidatedTime();
if ((System.currentTimeMillis() - lastCheck) >= poolParams.backgroundInterval)
{
cls.remove(cl);
break;
}
else
{
cl = null;
}
}
return cl;
}
private void returnForFrequencyCheck(ConnectionListener cl)
{
log.debug("Returning for connection within frequency");
cl.setLastValidatedTime(System.currentTimeMillis());
cls.add(cl);
}
/**
* Guard against configurations or
* dynamic changes that may increase the minimum
* beyond the maximum
*/
private int getMinSize()
{
if (poolParams.minSize > maxSize)
return maxSize;
return poolParams.minSize;
}
public static class PoolParams
{
public int minSize = 0;
public int maxSize = 10;
public int blockingTimeout = 30000; // milliseconds
public long idleTimeout = 1000 * 60 * 30; // milliseconds, 30 minutes.
public long backgroundInterval = 0;
public boolean prefill;
public boolean stictMin;
//Do we want to immeadiately break when a connection cannot be matched and not evaluate the rest of the pool?
public boolean useFastFail;
}
/**
* Stats
*/
private static class Counter
{
private int created = 0;
private int destroyed = 0;
// Total wait time to get Connection from Pool.
private long totalBlockTime;
// Idle timed out Connection Count.
private int timedOut;
// The maximum wait time */
private long maxWaitTime;
synchronized int getGuaranteedCount()
{
return created - destroyed;
}
int getCount()
{
return created - destroyed;
}
int getCreatedCount()
{
return created;
}
int getDestroyedCount()
{
return destroyed;
}
synchronized void inc()
{
++created;
}
synchronized void dec()
{
++destroyed;
}
synchronized void updateBlockTime(long latest)
{
totalBlockTime += latest;
if (maxWaitTime < latest)
maxWaitTime = latest;
}
long getTotalBlockTime()
{
return totalBlockTime;
}
int getTimedOut()
{
return timedOut;
}
synchronized void incTimedOut()
{
++timedOut;
}
long getMaxWaitTime()
{
return maxWaitTime;
}
}
}