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* Filename: $File$
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* Copyright 2000-2001 by iPlanet/Sun Microsystems, Inc.,
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/**
* <BR> <I>$Source: /cvs/glassfish/appserv-commons/src/java/com/sun/enterprise/util/pool/ObjectPool.java,v $</I>
* @author $Author: tcfujii $
* @version $Revision: 1.5 $ $Date: 2007/05/05 05:32:16 $
*/
package com.sun.enterprise.util.pool;
import java.util.List;
import java.util.Iterator;
import java.util.ArrayList;
import java.util.Collection;
import java.lang.ref.Reference;
import java.lang.ref.SoftReference;
import com.sun.enterprise.util.scheduler.PeriodicallyServicable;
import com.sun.enterprise.util.scheduler.PeriodicEventScheduler;
import com.sun.enterprise.util.ApproximateClock;
import com.sun.enterprise.util.collection.DList;
import com.sun.enterprise.util.collection.DListNode;
import com.sun.enterprise.util.collection.DListNodeFactory;
import com.sun.enterprise.util.collection.FastStack;
//Bug 4677074 begin
import java.util.logging.Logger;
import java.util.logging.Level;
import com.sun.logging.LogDomains;
//Bug 4677074 end
public class ObjectPool
extends com.sun.enterprise.util.pool.AbstractPool
implements PeriodicallyServicable
{
//Bug 4677074 begin
static Logger _logger=LogDomains.getLogger(LogDomains.UTIL_LOGGER);
//Bug 4677074 end
protected DList list;
protected int minSize;
protected int initialSize;
protected int maxLimit;
protected long maxIdleTime;
protected Boolean isBounded;
/**
* Create an Unbounded pool.
* @param The ObjectFactory to create objects
* @param The minimum number of objects to be held in the pool (initial size)
* @param The pool limit (maximum number of objects in the pool).
* @param The maximum idle time after which the object may be removed from the pool.
*/
public ObjectPool(ObjectFactory factory, int minSize, int initialSize, long maxIdleTime) {
super();
super.factory = factory;
this.minSize = minSize;
this.initialSize = initialSize;
this.maxIdleTime = maxIdleTime;
setMaxLimit(-1);
initPool();
}
/**
* Create a Bounded pool.
* @param The ObjectFactory to create objects
* @param The minimum number of objects to be held in the pool (initial size)
* @param The pool limit (maximum number of objects in the pool).
* @param The maximum idle time after which the object may be removed from the pool.
* @param The initial size of the pool. If this is less than the minSize parameter then this is ignored.
*/
public ObjectPool(ObjectFactory factory, int minSize, int initialSize, int maxLimit,
long maxIdleTime)
{
super();
super.factory = factory;
this.minSize = minSize;
this.maxIdleTime = maxIdleTime;
this.initialSize = initialSize;
setMaxLimit(maxLimit);
initPool();
}
public int getMaxLimit() {
return this.maxLimit;
}
public void setMaxLimit(int limit) {
if ((limit <= 0) || (limit >= Integer.MAX_VALUE-1)) {
this.isBounded = null;
} else {
this.isBounded = Boolean.valueOf(true);
this.maxLimit = limit;
}
}
private void initPool() {
list = new DList();
super.collection = list;
super.preload((minSize < initialSize) ? initialSize : minSize);
scheduler.addTimeRepeatableTask(this, (int) maxIdleTime);
}
/**
* Since this method would be called only if the pool is empty
*/
protected boolean canCreate() {
return (isBounded == null) ? true : (createdCount < maxLimit);
}
/**
* Notification when an object is put back into the pool (checkin).
* @param The object to be returned back to the pool.
* @return Any non null value can be returned to signal that the object
* was indeed added to the pool. This class always adds the object to the
* pool (at the end of the list), it returns non-null value.
* Subclasses can override this behaviour.
*/
protected Object checkin(Object object) {
list.addAsLastNode(new TimeStampedDListNode(object, _clock.getTime()));
return this;
}
private Object obtainObject(Object param) {
SoftReference ref;
Object object;
TimeStampedDListNode tsNode = (TimeStampedDListNode) list.delinkLastNode();
return tsNode.object;
}
/**
* Notification when an object is given out from the pool (checout).
* @return The object that has to be returned to the application. A null
* value must be returned if no object can be returned to the application. Since this
* class always returns the last node from the list, it returns non-null value.
* Subclasses can override this behaviour.
*/
protected Object checkout(Object param) {
return obtainObject(param);
}
//Methods required for periodically schedulable task
public void prolog() {
}
public void service() {
int killedCount = 0;
long now = _clock.getTime();
long allowed = now - maxIdleTime;
TimeStampedDListNode tsNode = null;
FastStack stack = new FastStack();
synchronized (super.collection) {
Object done = null;
while (done == null) {
tsNode = (TimeStampedDListNode) list.getFirstDListNode();
if (tsNode == null) { //Empty list
done = new Object();
} else if (tsNode.timeStamp <= allowed) {
//Need to destroy the contained object
list.delink(tsNode);
stack.push(tsNode.object);
killedCount++;
} else {
//This node is not old enough
done = new Object();
}
} //End of for loop
super.createdCount -= killedCount;
if (createdCount < minSize) {
super.preload(minSize - createdCount);
}
if (waitCount > 0) {
if (killedCount == 1) {
collection.notify();
} else {
collection.notifyAll();
}
}
} // end of synchronized
//Now destroy all collected objects
while (! stack.isEmpty()) {
Object object = stack.pop();
beforeDestroy(object);
factory.destroy(object);
}
//Bug 4677074 System.out.println("Leaving service after killing " + killedCount + " (idle) objects. Now size: " + list.size());
//Bug 4677074 begin
_logger.log(Level.FINE,"Leaving service after killing " + killedCount + " (idle) objects. Now size: " + list.size());
//Bug 4677074 end
}
public void epilog() {
}
/**
* Get the frequency (time interval) at which service() method will be invoked.
* @return time in milli seconds.
*/
public long getFrequency() {
return this.maxIdleTime;
}
/**
* Determine to execute the service method of this object even if it has
* missed the right schedule.
*/
public boolean getExecuteIfMissed() {
return true;
}
/**
* Determine to execute the service method of this object when the
* schedule is delayed by 'missedByMillis' milli seconds.
*/
public boolean getExecutionTolerance(long missedByMillis) {
return true;
}
/**
* Print an identification for the object.
*/
public String toString() {
return "";
}
//Some helper classes
class TimeStampedDListNode
extends DListNode
{
long timeStamp;
public TimeStampedDListNode(Object object, long ts) {
super(object);
this.timeStamp = ts;
//System.out.println(this + ": created DListNode at: " + ts);
//Bug 4677074 begin
//_logger.log(Level.FINE,this + ": created DListNode at: " + ts);
//Bug 4677074 end
}
public String toString() {
return "TSDListNode: " + object;
}
}
}
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