/*
* Bitronix Transaction Manager
*
* Copyright (c) 2010, Bitronix Software.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program 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 distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package bitronix.tm.resource.common;
import java.util.ArrayList;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Queue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import javax.transaction.Synchronization;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import bitronix.tm.BitronixTransaction;
import bitronix.tm.BitronixXid;
import bitronix.tm.TransactionManagerServices;
import bitronix.tm.internal.BitronixRuntimeException;
import bitronix.tm.internal.XAResourceHolderState;
import bitronix.tm.recovery.IncrementalRecoverer;
import bitronix.tm.recovery.RecoveryException;
import bitronix.tm.utils.Decoder;
import bitronix.tm.utils.MonotonicClock;
import bitronix.tm.utils.Uid;
/**
* Generic XA pool. {@link XAStatefulHolder} instances are created by the {@link XAPool} out of a
* {@link XAResourceProducer}. Those objects are then pooled and can be retrieved and/or recycled by the pool
* depending on the running XA transaction's and the {@link XAStatefulHolder}'s states.
*
* @author lorban
* @author Brett Wooldridge
*/
public class XAPool implements StateChangeListener {
private final static Logger log = LoggerFactory.getLogger(XAPool.class);
/**
* The stateTransitionLock makes sure that transitions of XAStatefulHolders from one state to another
* (movement from one pool to another) are atomic. A ReentrantReadWriteLock allows any number of
* readers to access and iterate the accessiblePool and inaccessiblePool without blocking. Readers
* are blocked only for the instant when a connection is moving between pools. These locks are
* sufficient to protect the collections, which are left intentionally non-concurrent so that failures
* in locking logic will be quickly uncovered.
*/
private final ReentrantReadWriteLock stateTransitionLock = new ReentrantReadWriteLock();
private final BlockingQueue<XAStatefulHolder> availablePool = new LinkedBlockingQueue<XAStatefulHolder>();
private final Queue<XAStatefulHolder> accessiblePool = new LinkedList<XAStatefulHolder>();
private final Queue<XAStatefulHolder> inaccessiblePool = new LinkedList<XAStatefulHolder>();
/**
* This map is used to implement the connection sharing feature of Bitronix.
*/
private final Map<Uid, StatefulHolderThreadLocal> statefulHolderTransactionMap = new ConcurrentHashMap<Uid, StatefulHolderThreadLocal>();
private final ResourceBean bean;
private final XAResourceProducer xaResourceProducer;
private final Object xaFactory;
private final AtomicBoolean failed = new AtomicBoolean();
public XAPool(XAResourceProducer xaResourceProducer, ResourceBean bean) throws Exception {
this.xaResourceProducer = xaResourceProducer;
this.bean = bean;
if (bean.getMaxPoolSize() < 1 || bean.getMinPoolSize() > bean.getMaxPoolSize())
throw new IllegalArgumentException("cannot create a pool with min " + bean.getMinPoolSize() + " connection(s) and max " + bean.getMaxPoolSize() + " connection(s)");
if (bean.getAcquireIncrement() < 1)
throw new IllegalArgumentException("cannot create a pool with a connection acquisition increment less than 1, configured value is " + bean.getAcquireIncrement());
xaFactory = XAFactoryHelper.createXAFactory(bean);
init();
if (bean.getIgnoreRecoveryFailures())
log.warn("resource '" + bean.getUniqueName() + "' is configured to ignore recovery failures, make sure this setting is not enabled on a production system!");
}
private void init() throws Exception {
growUntilMinPoolSize();
if (bean.getMaxIdleTime() > 0 || bean.getMaxLifeTime() > 0) {
TransactionManagerServices.getTaskScheduler().schedulePoolShrinking(this);
}
}
/**
* Close down and cleanup this XAPool instance.
*/
public synchronized void close() {
if (log.isDebugEnabled()) { log.debug("closing all connections of " + this); }
for (XAStatefulHolder xaStatefulHolder : getXAResourceHolders()) {
try {
xaStatefulHolder.close();
} catch (Exception ex) {
if (log.isDebugEnabled()) { log.debug("ignoring exception while closing connection " + xaStatefulHolder, ex); }
}
}
if (TransactionManagerServices.isTaskSchedulerRunning())
TransactionManagerServices.getTaskScheduler().cancelPoolShrinking(this);
stateTransitionLock.writeLock().lock();
try {
availablePool.clear();
accessiblePool.clear();
inaccessiblePool.clear();
failed.set(false);
}
finally {
stateTransitionLock.writeLock().unlock();
}
}
/**
* Get a connection handle from this pool.
*
* @return a connection handle
* @throws Exception throw in the pool is unrecoverable or a timeout occurs getting a connection
*/
public Object getConnectionHandle() throws Exception {
return getConnectionHandle(true);
}
/**
* Get a connection handle from this pool.
*
* @param recycle true if we should try to get a connection in the NON_ACCESSIBLE pool in the same transaction
* @return a connection handle
* @throws Exception throw in the pool is unrecoverable or a timeout occurs getting a connection
*/
public Object getConnectionHandle(boolean recycle) throws Exception {
if (isFailed()) {
reinitializePool();
}
long remainingTimeMs = bean.getAcquisitionTimeout() * 1000L;
while (true) {
long before = MonotonicClock.currentTimeMillis();
XAStatefulHolder xaStatefulHolder = null;
if (recycle) {
if (bean.getShareTransactionConnections()) {
xaStatefulHolder = getSharedXAStatefulHolder();
}
else {
xaStatefulHolder = getNotAccessible();
}
}
if (xaStatefulHolder == null) {
xaStatefulHolder = getInPool(remainingTimeMs);
}
if (log.isDebugEnabled()) { log.debug("found " + Decoder.decodeXAStatefulHolderState(xaStatefulHolder.getState()) + " connection " + xaStatefulHolder + " from " + this); }
try {
// getConnectionHandle() here could throw an exception, if it doesn't the connection is
// still alive and we can share it (if sharing is enabled)
Object connectionHandle = xaStatefulHolder.getConnectionHandle();
if (bean.getShareTransactionConnections()) {
putSharedXAStatefulHolder(xaStatefulHolder);
}
try {
growUntilMinPoolSize();
}
catch (Exception e) {
log.warn("exception while trying to fill pool to minimum size");
}
return connectionHandle;
} catch (Exception ex) {
if (log.isDebugEnabled()) { log.debug("connection is invalid, trying to close it", ex); }
try {
xaStatefulHolder.close();
} catch (Exception ex2) {
if (log.isDebugEnabled()) { log.debug("exception while trying to close invalid connection, ignoring it", ex2); }
}
finally {
if (log.isDebugEnabled()) { log.debug("removed invalid connection " + xaStatefulHolder + " from " + this); }
if (xaStatefulHolder.getState() != XAStatefulHolder.STATE_CLOSED) {
stateChanged(xaStatefulHolder, xaStatefulHolder.getState(), XAStatefulHolder.STATE_CLOSED);
}
if (log.isDebugEnabled()) log.debug("waiting " + bean.getAcquisitionInterval() + "s before trying to acquire a connection again from " + this);
long waitTime = TimeUnit.SECONDS.toMillis(bean.getAcquisitionInterval());
if (waitTime > 0) {
try {
synchronized (this) {
wait(waitTime);
}
} catch (InterruptedException ex2) {
// ignore
}
}
}
// check for timeout
long now = MonotonicClock.currentTimeMillis();
remainingTimeMs -= (now - before);
before = now;
if (remainingTimeMs <= 0) {
throw new BitronixRuntimeException("cannot get valid connection from " + this + " after trying for " + bean.getAcquisitionTimeout() + "s", ex);
}
}
} // while true
}
public void stateChanging(XAStatefulHolder source, int currentState, int futureState) {
stateTransitionLock.writeLock().lock();
try {
switch (currentState) {
case XAStatefulHolder.STATE_IN_POOL:
if (log.isDebugEnabled()) { log.debug("removed " + source + " from the available pool"); }
availablePool.remove(source);
break;
case XAStatefulHolder.STATE_ACCESSIBLE:
if (log.isDebugEnabled()) { log.debug("removed " + source + " from the accessible pool"); }
accessiblePool.remove(source);
break;
case XAStatefulHolder.STATE_NOT_ACCESSIBLE:
if (log.isDebugEnabled()) { log.debug("removed " + source + " from the inaccessible pool"); }
inaccessiblePool.remove(source);
break;
case XAStatefulHolder.STATE_CLOSED:
source.removeStateChangeEventListener(this);
break;
}
}
finally {
stateTransitionLock.writeLock().unlock();
}
}
public void stateChanged(XAStatefulHolder source, int oldState, int newState) {
stateTransitionLock.writeLock().lock();
try {
switch (newState) {
case XAStatefulHolder.STATE_IN_POOL:
if (log.isDebugEnabled()) { log.debug("added " + source + " to the available pool"); }
availablePool.add(source);
break;
case XAStatefulHolder.STATE_ACCESSIBLE:
if (log.isDebugEnabled()) { log.debug("added " + source + " to the accessible pool"); }
accessiblePool.add(source);
break;
case XAStatefulHolder.STATE_NOT_ACCESSIBLE:
if (log.isDebugEnabled()) { log.debug("added " + source + " to the inaccessible pool"); }
inaccessiblePool.add(source);
break;
case XAStatefulHolder.STATE_CLOSED:
source.removeStateChangeEventListener(this);
break;
}
}
finally {
stateTransitionLock.writeLock().unlock();
}
}
/**
* Get a XAStatefulHolder (connection) from the NOT_ACCESSIBLE pool.
*
* @return a connection, or null if there are no connections in the inaccessible pool for the current transaction
*/
private XAStatefulHolder getNotAccessible() {
if (log.isDebugEnabled()) { log.debug("trying to recycle a NOT_ACCESSIBLE connection of " + this); }
BitronixTransaction transaction = TransactionContextHelper.currentTransaction();
if (transaction == null) {
if (log.isDebugEnabled()) { log.debug("no current transaction, no connection can be in state NOT_ACCESSIBLE when there is no global transaction context"); }
return null;
}
Uid currentTxGtrid = transaction.getResourceManager().getGtrid();
if (log.isDebugEnabled()) { log.debug("current transaction GTRID is [" + currentTxGtrid + "]"); }
stateTransitionLock.readLock().lock();
try {
for (XAStatefulHolder xaStatefulHolder : inaccessiblePool) {
if (log.isDebugEnabled()) { log.debug("found a connection in NOT_ACCESSIBLE state: " + xaStatefulHolder); }
if (containsXAResourceHolderMatchingGtrid(xaStatefulHolder, currentTxGtrid))
return xaStatefulHolder;
} // for
if (log.isDebugEnabled()) { log.debug("no NOT_ACCESSIBLE connection enlisted in this transaction"); }
return null;
}
finally {
stateTransitionLock.readLock().unlock();
}
}
private boolean containsXAResourceHolderMatchingGtrid(XAStatefulHolder xaStatefulHolder, final Uid currentTxGtrid) {
List<XAResourceHolder> xaResourceHolders = xaStatefulHolder.getXAResourceHolders();
if (log.isDebugEnabled()) { log.debug(xaResourceHolders.size() + " xa resource(s) created by connection in NOT_ACCESSIBLE state: " + xaStatefulHolder); }
for (XAResourceHolder xaResourceHolder : xaResourceHolders) {
class LocalVisitor implements XAResourceHolderStateVisitor {
private boolean found;
public boolean visit(XAResourceHolderState xaResourceHolderState) {
// compare GTRIDs
BitronixXid bitronixXid = xaResourceHolderState.getXid();
Uid resourceGtrid = bitronixXid.getGlobalTransactionIdUid();
if (log.isDebugEnabled()) { log.debug("NOT_ACCESSIBLE xa resource GTRID: " + resourceGtrid); }
if (currentTxGtrid.equals(resourceGtrid)) {
if (log.isDebugEnabled()) { log.debug("NOT_ACCESSIBLE xa resource's GTRID matched this transaction's GTRID, recycling it"); }
found = true;
}
return !found; // continue visitation if not found, stop visitation if found
}
}
LocalVisitor xaResourceHolderStateVisitor = new LocalVisitor();
xaResourceHolder.acceptVisitorForXAResourceHolderStates(currentTxGtrid, xaResourceHolderStateVisitor);
if (xaResourceHolderStateVisitor.found) {
return true;
}
}
return false;
}
/**
* Get an IN_POOL connection. This method blocks for up to remainingTimeMs milliseconds
* for someone to return or create a connection in the available pool. If remainingTimeMs
* expires, an exception is thrown.
*
* @param remainingTimeMs the maximum time to wait for a connection
* @return a connection from the available (IN_POOL) pool
* @throws Exception thrown in no connection is available before the remainingTimeMs time expires
*/
private XAStatefulHolder getInPool(long remainingTimeMs) throws Exception {
if (log.isDebugEnabled()) { log.debug("getting a IN_POOL connection from " + this); }
if (inPoolSize() == 0) {
if (log.isDebugEnabled()) { log.debug("no more free connections in " + this + ", trying to grow it"); }
grow();
}
if (log.isDebugEnabled()) { log.debug("getting IN_POOL connection, waiting if necessary, current size is " + inPoolSize()); }
try {
XAStatefulHolder xaStatefulHolder = availablePool.poll(remainingTimeMs, TimeUnit.MILLISECONDS);
if (xaStatefulHolder == null) {
if (TransactionManagerServices.isTransactionManagerRunning())
TransactionManagerServices.getTransactionManager().dumpTransactionContexts();
throw new BitronixRuntimeException("XA pool of resource " + bean.getUniqueName() + " still empty after " + bean.getAcquisitionTimeout() + "s wait time");
}
return xaStatefulHolder;
} catch (InterruptedException e) {
throw new BitronixRuntimeException("Interrupted while waiting for IN_POOL connection.");
}
}
/* ------------------------------------------------------------------------
* Pool growth and pooled object creation
* ------------------------------------------------------------------------*/
/**
* Grow the pool by "acquire increment" amount up to the max pool size.
*
* @throws Exception thrown if creating a pooled objects fails
*/
private synchronized void grow() throws Exception {
final long totalPoolSize = totalPoolSize();
if (totalPoolSize < bean.getMaxPoolSize()) {
long increment = bean.getAcquireIncrement();
if (totalPoolSize + increment > bean.getMaxPoolSize()) {
increment = bean.getMaxPoolSize() - totalPoolSize;
}
if (log.isDebugEnabled()) { log.debug("incrementing " + bean.getUniqueName() + " pool size by " + increment + " unit(s) to reach " + (totalPoolSize() + increment) + " connection(s)"); }
for (int i=0; i < increment ;i++) {
createPooledObject(xaFactory);
}
}
else {
if (log.isDebugEnabled()) { log.debug("pool " + bean.getUniqueName() + " already at max size of " + totalPoolSize() + " connection(s), not growing it"); }
}
}
private synchronized void growUntilMinPoolSize() throws Exception {
if (log.isDebugEnabled()) { log.debug("growing " + this + " to minimum pool size " + bean.getMinPoolSize()); }
for (int i = totalPoolSize(); i < bean.getMinPoolSize(); i++) {
createPooledObject(xaFactory);
}
}
private void createPooledObject(Object xaFactory) throws Exception {
XAStatefulHolder xaStatefulHolder = xaResourceProducer.createPooledConnection(xaFactory, bean);
xaStatefulHolder.addStateChangeEventListener(this);
availablePool.add(xaStatefulHolder);
}
/* ------------------------------------------------------------------------
* Pool shrinking and pooled object expiration.
* ------------------------------------------------------------------------*/
public Date getNextShrinkDate() {
return new Date(MonotonicClock.currentTimeMillis() + bean.getMaxIdleTime() * 1000);
}
public void shrink() throws Exception {
if (log.isDebugEnabled()) { log.debug("shrinking " + this); }
expireOrCloseStatefulHolders(false);
if (log.isDebugEnabled()) { log.debug("shrunk " + this); }
}
public void reset() throws Exception {
if (log.isDebugEnabled()) { log.debug("resetting " + this); }
expireOrCloseStatefulHolders(true);
if (log.isDebugEnabled()) { log.debug("reset " + this); }
}
private synchronized void expireOrCloseStatefulHolders(boolean forceClose) throws Exception {
int closed = 0;
final long now = MonotonicClock.currentTimeMillis();
final int availableSize = availablePool.size();
for (int i = 0; i < availableSize; i++) {
XAStatefulHolder xaStatefulHolder = availablePool.poll();
if (xaStatefulHolder == null) {
break;
}
long expirationTime = Integer.MAX_VALUE;
if (bean.getMaxIdleTime() > 0) {
expirationTime = (xaStatefulHolder.getLastReleaseDate().getTime() + (bean.getMaxIdleTime() * 1000));
}
if (bean.getMaxLifeTime() > 0) {
long endOfLife = xaStatefulHolder.getCreationDate().getTime() + (bean.getMaxLifeTime() * 1000);
expirationTime = Math.min(expirationTime, endOfLife);
}
if (!forceClose && log.isDebugEnabled()) { log.debug("checking if connection can be closed: " + xaStatefulHolder + " - closing time: " + expirationTime + ", now time: " + now); }
if (expirationTime <= now || forceClose) {
try {
closed++;
xaStatefulHolder.close();
} catch (Exception ex) {
log.warn("error closing " + xaStatefulHolder, ex);
}
} else {
availablePool.add(xaStatefulHolder);
}
} // for
if (log.isDebugEnabled()) { log.debug("closed " + closed + (forceClose ? " " : " idle ") + "connection(s)"); }
growUntilMinPoolSize();
}
private void reinitializePool() {
synchronized (this) {
try {
if (isFailed()) {
if (log.isDebugEnabled()) { log.debug("resource '" + bean.getUniqueName() + "' is marked as failed, resetting and recovering it before trying connection acquisition"); }
close();
init();
IncrementalRecoverer.recover(xaResourceProducer);
}
}
catch (RecoveryException ex) {
throw new BitronixRuntimeException("incremental recovery failed when trying to acquire a connection from failed resource '" + bean.getUniqueName() + "'", ex);
}
catch (Exception ex) {
throw new BitronixRuntimeException("pool reset failed when trying to acquire a connection from failed resource '" + bean.getUniqueName() + "'", ex);
}
}
}
/* ------------------------------------------------------------------------
* Miscellaneous public accessors
* ------------------------------------------------------------------------*/
/**
* Get the XAFactory (XADataSource) that produces objects for this pool.
*
* @return the factory (XADataSource) object
*/
public Object getXAFactory() {
return xaFactory;
}
/**
* Sets this XAPool as failed or unfailed, requiring recovery.
*
* @param failed true if this XAPool has failed and requires recovery, false if it is ok
*/
public void setFailed(boolean failed) {
this.failed.set(failed);
}
/**
* Is the XAPool in a failed state?
*
* @return true if this XAPool has failed, false otherwise
*/
public boolean isFailed() {
return failed.get();
}
/**
* Get the total size of this pool.
*
* @return the total size of this pool
*/
public int totalPoolSize() {
return availablePool.size() + accessiblePool.size() + inaccessiblePool.size();
}
/**
* Get the number of objects in the available pool.
*
* @return the number of available objects
*/
public int inPoolSize() {
return availablePool.size();
}
public List<XAStatefulHolder> getXAResourceHolders() {
stateTransitionLock.readLock().lock();
try {
List<XAStatefulHolder> holders = new ArrayList<XAStatefulHolder>();
holders.addAll(availablePool);
holders.addAll(accessiblePool);
holders.addAll(inaccessiblePool);
return holders;
}
finally {
stateTransitionLock.readLock().unlock();
}
}
/* ------------------------------------------------------------------------
* Shared Connection Handling
* ------------------------------------------------------------------------*/
/**
* Try to get a shared XAStatefulHolder. This method will either return
* a shared XAStatefulHolder or <code>null</code>. If there is no current
* transaction, XAStatefulHolder's are not shared. If there is a transaction
* <i>and</i> there is a XAStatefulHolder associated with this thread already,
* we return that XAStatefulHolder (provided it is ACCESSIBLE or NOT_ACCESSIBLE).
*
* @return a shared XAStatefulHolder or <code>null</code>
*/
private XAStatefulHolder getSharedXAStatefulHolder() {
BitronixTransaction transaction = TransactionContextHelper.currentTransaction();
if (transaction == null) {
if (log.isDebugEnabled()) { log.debug("no current transaction, shared connection map will not be used"); }
return null;
}
Uid currentTxGtrid = transaction.getResourceManager().getGtrid();
StatefulHolderThreadLocal threadLocal = statefulHolderTransactionMap.get(currentTxGtrid);
if (threadLocal != null) {
XAStatefulHolder xaStatefulHolder = (XAStatefulHolder) threadLocal.get();
// Additional sanity checks...
if (xaStatefulHolder != null &&
xaStatefulHolder.getState() != XAStatefulHolder.STATE_IN_POOL &&
xaStatefulHolder.getState() != XAStatefulHolder.STATE_CLOSED) {
if (log.isDebugEnabled()) { log.debug("sharing connection " + xaStatefulHolder + " in transaction " + currentTxGtrid); }
return xaStatefulHolder;
}
}
return null;
}
/**
* Try to share a XAStatefulHolder with other callers on this thread. If
* there is no current transaction, the XAStatefulHolder is not put into the
* ThreadLocal. If there is a transaction, and it is the first time we're
* attempting to share a XAStatefulHolder on this thread, then we register
* a Synchronization so we can pull the ThreadLocals out of the shared map
* when the transaction completes (either commit() or rollback()). Without
* the Synchronization we would "leak".
*
* @param xaStatefulHolder a XAStatefulHolder to share with other callers
* on this thread.
*/
private void putSharedXAStatefulHolder(final XAStatefulHolder xaStatefulHolder) {
BitronixTransaction transaction = TransactionContextHelper.currentTransaction();
if (transaction == null) {
if (log.isDebugEnabled()) { log.debug("no current transaction, not adding " + xaStatefulHolder + " to shared connection map"); }
return;
}
final Uid currentTxGtrid = transaction.getResourceManager().getGtrid();
StatefulHolderThreadLocal threadLocal = statefulHolderTransactionMap.get(currentTxGtrid);
if (threadLocal == null) {
// This is the first time this TxGtrid/ThreadLocal is going into the map,
// register interest in synchronization so we can remove it at commit/rollback
try {
transaction.registerSynchronization(new SharedStatefulHolderCleanupSynchronization(currentTxGtrid));
} catch (Exception e) {
// OK, forget it. The transaction is either rollback only or already finished.
return;
}
threadLocal = new StatefulHolderThreadLocal();
statefulHolderTransactionMap.put(currentTxGtrid, threadLocal);
if (log.isDebugEnabled()) { log.debug("added shared connection mapping for " + currentTxGtrid + " holder " + xaStatefulHolder); }
}
// Set the XAStatefulHolder on the ThreadLocal. Even if we've already set it before,
// it's safe -- checking would be more expensive than just setting it again.
threadLocal.set(xaStatefulHolder);
}
private final class SharedStatefulHolderCleanupSynchronization implements Synchronization {
private final Uid gtrid;
private SharedStatefulHolderCleanupSynchronization(Uid gtrid) {
this.gtrid = gtrid;
}
public void beforeCompletion() {
}
public void afterCompletion(int status) {
statefulHolderTransactionMap.remove(gtrid);
if (log.isDebugEnabled()) { log.debug("deleted shared connection mappings for " + gtrid); }
}
public String toString() {
return "a SharedStatefulHolderCleanupSynchronization with GTRID [" + gtrid + "]";
}
}
private static final class StatefulHolderThreadLocal extends ThreadLocal<XAStatefulHolder>
{
@Override
public XAStatefulHolder get() {
return super.get();
}
@Override
public void set(XAStatefulHolder value) {
super.set(value);
}
}
public String toString() {
return "an XAPool of resource " + bean.getUniqueName() + " with " + totalPoolSize() + " connection(s) (" + inPoolSize() + " still available)" + (isFailed() ? " -failed-" : "");
}
}