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/**
* <BR> <I>$Source: /cvs/glassfish/appserv-core/src/java/com/sun/ejb/containers/util/pool/AbstractPool.java,v $</I>
* @author $Author: tcfujii $
* @version $Revision: 1.6 $ $Date: 2007/05/05 05:33:00 $
*/
package com.sun.ejb.containers.util.pool;
import java.util.ArrayList;
import java.util.logging.*;
import com.sun.enterprise.util.Utility;
import com.sun.ejb.containers.ContainerFactoryImpl;
import com.sun.logging.*;
/**
* <p>Abstract pool provides the basic implementation of an object pool.
* The implementation uses a linked list to maintain a list of (available)
* objects. If the pool is empty it simply creates one using the ObjectFactory
* instance. Subclasses can change this behaviour by overriding getObject(...)
* and returnObject(....) methods. This class provides basic support for
* synchronization, event notification, pool shutdown and pool object
* recycling. It also does some very basic bookkeeping like the
* number of objects created, number of threads waiting for object.
* <p> Subclasses can make use of these book-keeping data to provide complex
* pooling mechanism like LRU / MRU / Random. Also, note that AbstractPool
* does not have a notion of pool limit. It is upto to the derived classes
* to implement these features.
*/
public abstract class AbstractPool
implements Pool, com.sun.ejb.spi.stats.EJBPoolStatsProvider
{
protected static final Logger _logger =
LogDomains.getLogger(LogDomains.EJB_LOGGER);
protected ArrayList list;
protected ObjectFactory factory = null;
protected int waitCount = 0;
protected int createdCount = 0;
protected int steadyPoolSize;
protected int resizeQuantity = 1;
protected int maxPoolSize = Integer.MAX_VALUE;
protected long maxWaitTimeInMillis;
protected int idleTimeoutInSeconds;
private AbstractPoolTimerTask poolTimerTask;
// class loader used as context class loader for asynchronous operations
protected ClassLoader containerClassLoader;
protected int destroyedCount = 0;
protected int poolSuccess = 0;
protected String poolName;
protected int poolReturned = 0;
protected String configData;
protected AbstractPool() {
}
protected AbstractPool(ObjectFactory factory, int steadyPoolSize,
int resizeQuantity, int maxPoolsize, long maxWaitTimeInMillis,
int idleTimeoutInSeconds, ClassLoader loader) {
initializePool(factory, steadyPoolSize, resizeQuantity, maxPoolsize,
maxWaitTimeInMillis, idleTimeoutInSeconds, loader);
}
protected void initializePool(ObjectFactory factory, int steadyPoolSize,
int resizeQuantity, int maxPoolsize, long maxWaitTimeInMillis,
int idleTimeoutInSeconds, ClassLoader loader) {
list = new ArrayList();
this.factory = factory;
this.steadyPoolSize = steadyPoolSize;
this.resizeQuantity = resizeQuantity;
this.maxPoolSize = maxPoolsize;
this.maxWaitTimeInMillis = maxWaitTimeInMillis;
this.idleTimeoutInSeconds = idleTimeoutInSeconds;
if (steadyPoolSize > 0) {
for (int i=0; i<steadyPoolSize; i++) {
list.add(factory.create(null));
createdCount++;
}
}
this.containerClassLoader = loader;
if (this.idleTimeoutInSeconds > 0) {
try {
this.poolTimerTask = new AbstractPoolTimerTask();
ContainerFactoryImpl.getTimer().scheduleAtFixedRate
(poolTimerTask, idleTimeoutInSeconds*1000,
idleTimeoutInSeconds*1000);
} catch (Throwable th) {
_logger.log(Level.WARNING,
"[AbstractPool]: Could not add AbstractPoolTimerTask" +
" ... Continuing anyway...");
}
}
}
public void setContainerClassLoader(ClassLoader loader) {
this.containerClassLoader = loader;
}
/**
* Get an object. Application can use pool.getObject() to get an object
* instead of using new XXX().
* @param canWait Must be true if the calling thread is willing to
* wait for infinite time to get an object, false if the calling thread
* does not want to wait at all.
*
*/
public Object getObject(boolean canWait, Object param)
throws PoolException
{
return getObject(param);
}
public Object getObject(long maxWaitTime, Object param)
throws PoolException
{
return getObject(param);
}
public Object getObject(Object param)
throws PoolException
{
long t1=0, totalWaitTime = 0;
int size;
synchronized (list) {
while (true) {
if ((size = list.size()) > 0) {
poolSuccess++;
return list.remove(size-1);
} else if ((createdCount - destroyedCount) < maxPoolSize) {
createdCount++; //hope that everything will be OK.
break;
}
if (maxWaitTimeInMillis >= 0) {
waitCount++;
t1 = System.currentTimeMillis();
try {
_logger.log(Level.FINE, "[AbstractPool]: Waiting on" +
" the pool to get a bean instance...");
list.wait(maxWaitTimeInMillis);
} catch (InterruptedException inEx) {
throw new PoolException("Thread interrupted.", inEx);
}
waitCount--;
totalWaitTime += System.currentTimeMillis() - t1;
if ((size = list.size()) > 0) {
poolSuccess++;
return list.remove(size-1);
} else if (maxWaitTimeInMillis == 0) {
// nothing special to do in this case
} else if (totalWaitTime >= maxWaitTimeInMillis) {
throw new PoolException("Pool Instance not obtained" +
" within given time interval.");
}
} else {
throw new PoolException("Pool Instance not obtained" +
" within given time interval.");
}
}
}
try {
return factory.create(param);
} catch (Exception poolEx) {
synchronized (list) {
createdCount--;
}
throw new RuntimeException("Caught Exception when trying " +
"to create pool Object ", poolEx);
}
}
/**
* Return an object back to the pool. An object that is obtained through
* getObject() must always be returned back to the pool using either
* returnObject(obj) or through destroyObject(obj).
*/
public void returnObject(Object object) {
synchronized (list) {
list.add(object);
poolReturned++;
if (waitCount > 0) {
list.notify();
}
}
}
/**
* Destroys an Object. Note that applications should not ignore the
* reference to the object that they got from getObject(). An object
* that is obtained through getObject() must always be returned back to
* the pool using either returnObject(obj) or through destroyObject(obj).
* This method tells that the object should be destroyed and cannot
* be reused.
*/
public void destroyObject(Object object) {
synchronized (list) {
destroyedCount++;
if (waitCount > 0) {
list.notify();
}
}
try {
factory.destroy(object);
} catch (Exception ex) {
_logger.log(Level.FINE, "Exception in destroyObject()", ex);
}
}
/**
* Preload the pool with objects.
* @param count the number of objects to be added.
*/
protected void preload(int count) {
synchronized (list) {
for (int i=0; i<count; i++) {
try {
list.add(factory.create(null));
createdCount++;
} catch (PoolException poolEx) {
_logger.log(Level.FINE, "Exception in preload()", poolEx);
}
}
}
}
/**
* Close the pool
*/
public void close() {
synchronized (list) {
if (poolTimerTask != null) {
try {
poolTimerTask.cancel();
_logger.log(Level.WARNING,
"[AbstractPool]: Cancelled pool timer task "
+ " at: " + (new java.util.Date()));
} catch (Throwable th) {
//Can safely ignore this!!
}
}
_logger.log(Level.FINE,"[AbstractPool]: Destroying "
+ list.size() + " beans from the pool...");
// since we're calling into ejb code, we need to set context
// class loader
ClassLoader origLoader =
Utility.setContextClassLoader(containerClassLoader);
Object[] array = list.toArray();
for (int i=0; i<array.length; i++) {
try {
destroyedCount++;
try {
factory.destroy(array[i]);
} catch (Throwable th) {
_logger.log(Level.FINE, "Exception in destroy()", th);
}
} catch (Throwable th) {
_logger.log(Level.WARNING,
"[AbstractPool]: Error while destroying: " + th);
}
}
_logger.log(Level.FINE,"[AbstractPool]: Pool closed....");
list = new ArrayList();
Utility.setContextClassLoader(origLoader);
}
// helps garbage collection
this.list = null;
this.factory = null;
this.poolTimerTask = null;
this.containerClassLoader = null;
}
protected void remove(int count) {
ArrayList removeList = new ArrayList();
synchronized (list) {
int size = list.size();
for (int i=0; (i<count) && (size > 0); i++) {
removeList.add(list.remove(--size));
destroyedCount++;
}
list.notifyAll();
}
for (int i=removeList.size()-1; i >= 0; i--) {
factory.destroy(removeList.remove(i));
try {
factory.destroy(removeList.remove(i));
} catch (Throwable th) {
_logger.log(Level.FINE, "Exception in destroy()", th);
}
}
}
protected abstract void removeIdleObjects();
private class AbstractPoolTimerTask
extends java.util.TimerTask
{
Object lock;
AbstractPoolTimerTask() {}
AbstractPoolTimerTask(Object lock) {
this.lock = lock;
}
public void run() {
//We need to set the context class loader for this (deamon)thread!!
final Thread currentThread = Thread.currentThread();
final ClassLoader previousClassLoader =
currentThread.getContextClassLoader();
final ClassLoader ctxClassLoader = containerClassLoader;
try {
if(System.getSecurityManager() == null) {
currentThread.setContextClassLoader(ctxClassLoader);
} else {
java.security.AccessController.doPrivileged(
new java.security.PrivilegedAction() {
public java.lang.Object run() {
currentThread.setContextClassLoader(ctxClassLoader);
return null;
}
});
}
try {
if (list.size() > steadyPoolSize) {
_logger.log(Level.FINE,"[AbstractPool]: Removing idle "
+ " objects from pool. Current Size: "
+ list.size() + "/" + steadyPoolSize
+ ". Time: " + (new java.util.Date()));
removeIdleObjects();
}
} catch (Throwable th) {
//removeIdleObjects would have logged the error
}
if(System.getSecurityManager() == null) {
currentThread.setContextClassLoader(previousClassLoader);
} else {
java.security.AccessController.doPrivileged(
new java.security.PrivilegedAction() {
public java.lang.Object run() {
currentThread.setContextClassLoader(previousClassLoader);
return null;
}
});
}
} catch (Throwable th) {
_logger.log(Level.FINE, "Exception in run()", th);
}
}
}
/**************** For Monitoring ***********************/
/*******************************************************/
public int getCreatedCount() {
return createdCount;
}
public int getDestroyedCount() {
return destroyedCount;
}
public int getPoolSuccess() {
return poolSuccess;
}
public int getSize() {
return list.size();
}
public int getWaitCount() {
return waitCount;
}
public int getSteadyPoolSize() {
return steadyPoolSize;
}
public int getResizeQuantity() {
return resizeQuantity;
}
public int getMaxPoolSize() {
return maxPoolSize;
}
public long getMaxWaitTimeInMillis() {
return maxWaitTimeInMillis;
}
public int getIdleTimeoutInSeconds() {
return idleTimeoutInSeconds;
}
public void setConfigData(String configData) {
this.configData = configData;
}
//Methods on EJBPoolStatsProvider
public void appendStats(StringBuffer sbuf) {
sbuf.append("[Pool: ")
.append("SZ=").append(list.size()).append("; ")
.append("CC=").append(createdCount).append("; ")
.append("DC=").append(destroyedCount).append("; ")
.append("WC=").append(waitCount).append("; ")
.append("MSG=0");
if (configData != null) {
sbuf.append(configData);
}
sbuf.append("]");
}
public int getJmsMaxMessagesLoad() {
return 0;
}
public int getNumBeansInPool() {
return list.size();
}
public int getNumThreadsWaiting() {
return waitCount;
}
public int getTotalBeansCreated() {
return createdCount;
}
public int getTotalBeansDestroyed() {
return destroyedCount;
}
public String getAllMonitoredAttrbuteValues() {
StringBuffer sbuf = new StringBuffer();
synchronized (list) {
sbuf.append("createdCount=").append(createdCount).append(";")
.append("destroyedCount=").append(destroyedCount).append(";")
.append("waitCount=").append(waitCount).append(";")
.append("size=").append(list.size()).append(";");
}
sbuf.append("maxPoolSize=").append(maxPoolSize).append(";");
return sbuf.toString();
}
public String getAllAttrValues() {
StringBuffer sbuf = new StringBuffer();
if(null != poolName)
sbuf.append(":").append(poolName);
else
sbuf.append(":POOL");
sbuf.append("[FP=").append(poolSuccess).append(",")
.append("TC=").append(createdCount).append(",")
.append("TD=").append(destroyedCount).append(",")
.append("PR=").append(poolReturned).append(",")
.append("TW=").append(waitCount).append(",")
.append("CS=").append(list.size()).append(",")
.append("MS=").append(maxPoolSize);
return sbuf.toString();
}
}
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