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/**
* <BR> <I>$Source: /cvs/glassfish/appserv-core/src/java/com/sun/ejb/containers/util/pool/NonBlockingPool.java,v $</I>
* @author $Author: tcfujii $
* @version $Revision: 1.5 $ $Date: 2007/05/05 05:33:00 $
*/
package com.sun.ejb.containers.util.pool;
import java.util.*;
import com.sun.ejb.containers.ContainerFactoryImpl;
import java.util.logging.*;
import java.util.TimerTask;
import com.sun.logging.*;
import com.sun.enterprise.util.Utility;
import com.sun.ejb.containers.EJBContextImpl;
import com.sun.enterprise.util.threadpool.Servicable;
import com.sun.ejb.containers.util.ContainerWorkPool;
/**
* <p>NonBlockingPool 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 class NonBlockingPool
extends AbstractPool
{
private String poolName;
private TimerTask poolTimerTask;
protected boolean addedResizeTask = false;
protected boolean addedIdleBeanWork = false;
protected boolean inResizing = false;
private boolean maintainSteadySize = false;
private int resizeTaskCount;
private int timerTaskCount;
protected NonBlockingPool() {
}
public NonBlockingPool(String poolName, ObjectFactory factory,
int steadyPoolSize, int resizeQuantity,
int maxPoolSize, int idleTimeoutInSeconds,
ClassLoader loader)
{
this.poolName = poolName;
initializePool(factory, steadyPoolSize, resizeQuantity, maxPoolSize,
idleTimeoutInSeconds, loader);
}
protected void initializePool(ObjectFactory factory, int steadyPoolSize,
int resizeQuantity, int maxPoolSize, int idleTimeoutInSeconds,
ClassLoader loader)
{
list = new ArrayList();
this.factory = factory;
this.steadyPoolSize = (steadyPoolSize <= 0) ? 0 : steadyPoolSize;
this.resizeQuantity = (resizeQuantity <= 0) ? 0 : resizeQuantity;
this.maxPoolSize = (maxPoolSize <= 0)
? Integer.MAX_VALUE : maxPoolSize;
this.steadyPoolSize = (this.steadyPoolSize > this.maxPoolSize)
? this.maxPoolSize : this.steadyPoolSize;
this.idleTimeoutInSeconds =
(idleTimeoutInSeconds <= 0) ? 0 : idleTimeoutInSeconds;
this.containerClassLoader = loader;
this.maintainSteadySize = (this.steadyPoolSize > 0);
if ((this.idleTimeoutInSeconds > 0) && (this.resizeQuantity > 0)) {
try {
this.poolTimerTask = new PoolResizeTimerTask();
ContainerFactoryImpl.getTimer().scheduleAtFixedRate
(poolTimerTask, idleTimeoutInSeconds*1000,
idleTimeoutInSeconds*1000);
if(_logger.isLoggable(Level.FINE)) {
_logger.log(Level.FINE,
"[Pool-" + poolName + "]: Added PoolResizeTimerTask...");
}
} catch (Throwable th) {
_logger.log(Level.WARNING,"[Pool-" +
poolName + "]: Could not add"
+ " PoolTimerTask. Continuing anyway...", th);
}
}
}
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)
{
boolean toAddResizeTask = false;
Object obj = null;
synchronized (list) {
int size = list.size();
if (size > steadyPoolSize) {
poolSuccess++;
return list.remove(size-1);
} else if (size > 0) {
poolSuccess++;
if ((maintainSteadySize) && (addedResizeTask == false)) {
toAddResizeTask = addedResizeTask = true;
obj = list.remove(size-1);
} else {
return list.remove(size-1);
}
} else {
if ((maintainSteadySize) && (addedResizeTask == false)) {
toAddResizeTask = addedResizeTask = true;
}
createdCount++; //hope that everything will be OK.
}
}
if (toAddResizeTask) {
addResizeTaskForImmediateExecution();
}
if (obj != null) {
return obj;
}
try {
return factory.create(param);
} catch (RuntimeException th) {
synchronized (list) {
createdCount--;
}
throw th;
}
}
private void addResizeTaskForImmediateExecution() {
try {
ReSizeWork work = new ReSizeWork();
ContainerWorkPool.addLast(work);
if(_logger.isLoggable(Level.FINE)) {
_logger.log(Level.FINE,
"[Pool-" + poolName + "]: Added PoolResizeTimerTask...");
}
resizeTaskCount++;
} catch (Exception ex) {
synchronized (list) {
addedResizeTask = false;
}
if(_logger.isLoggable(Level.WARNING)) {
_logger.log(Level.WARNING,
"[Pool-"+poolName+"]: Cannot perform "
+ " pool resize task", ex);
}
}
}
/**
* 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) {
if (list.size() < maxPoolSize) {
list.add(object);
return;
} else {
destroyedCount++;
}
}
try {
factory.destroy(object);
} catch (Exception ex) {
_logger.log(Level.FINE, "exception in returnObj", ex);
}
}
/**
* 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++;
}
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) {
ArrayList instances = new ArrayList(count);
try {
for (int i=0; i<count; i++) {
instances.add(factory.create(null));
}
} catch (Exception ex) {
//Need not throw this exception up since we are pre-populating
}
int sz = instances.size();
if (sz == 0) {
return;
}
synchronized (list) {
for (int i=0; i<sz; i++) {
list.add(instances.get(i));
}
createdCount += sz;
}
}
/**
* Prepopulate the pool with objects.
* @param count the number of objects to be added.
*/
public void prepopulate(int count) {
this.steadyPoolSize = (count <= 0) ? 0 : count;
this.steadyPoolSize = (this.steadyPoolSize > this.maxPoolSize)
? this.maxPoolSize : this.steadyPoolSize;
if (this.steadyPoolSize > 0) {
preload(this.steadyPoolSize);
}
}
/**
* Close the pool
*/
public void close() {
synchronized (list) {
if (poolTimerTask != null) {
try {
poolTimerTask.cancel();
if(_logger.isLoggable(Level.FINE)) {
_logger.log(Level.FINE,
"[Pool-"+poolName+"]: Cancelled pool timer task "
+ " at: " + (new java.util.Date()));
}
} catch (Throwable th) {
//Can safely ignore this!!
}
}
if(_logger.isLoggable(Level.FINE)) {
_logger.log(Level.FINE,"[Pool-"+poolName+"]: 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 close", th);
}
} catch (Throwable th) {
_logger.log(Level.WARNING,
"[Pool-"+poolName+"]: Error while destroying", th);
}
}
if(_logger.isLoggable(Level.FINE)) {
_logger.log(Level.FINE,"Pool-"+poolName+"]: Pool closed....");
}
list.clear();
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++;
}
}
int sz = removeList.size();
for (int i=0; i<sz; i++) {
try {
factory.destroy(removeList.get(i));
} catch (Throwable th) {
_logger.log(Level.FINE, "exception in remove", th);
}
}
}
protected void removeIdleObjects() {
}
protected void doResize() {
//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;
long startTime = 0;
boolean enteredResizeBlock = false;
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;
}
});
}
if(_logger.isLoggable(Level.FINE)) {
_logger.log(Level.FINE,
"[Pool-"+poolName+"]: Resize started at: "
+ (new java.util.Date())+" steadyPoolSize ::"+steadyPoolSize
+ " resizeQuantity ::"+resizeQuantity+" maxPoolSize ::" +
maxPoolSize );
}
startTime = System.currentTimeMillis();
ArrayList removeList = new ArrayList();
int populateCount = 0;
synchronized (list) {
if (inResizing == true) {
return;
}
enteredResizeBlock = true;
inResizing = true;
int curSize = list.size();
if (curSize > steadyPoolSize) {
//possible to reduce pool size....
if ((idleTimeoutInSeconds <= 0) ||
(resizeQuantity <= 0)) {
return;
}
int victimCount =
(curSize > (steadyPoolSize + resizeQuantity) )
? resizeQuantity : (curSize - steadyPoolSize);
long allowedIdleTime = System.currentTimeMillis() -
idleTimeoutInSeconds*1000;
if(_logger.isLoggable(Level.FINE)) {
_logger.log(Level.FINE,
"[Pool-"+poolName+"]: Resize:: reducing "
+ " pool size by: " + victimCount);
}
for (int i=0; i<victimCount; i++) {
//removeList.add(list.remove(--curSize));
//destroyedCount++;
EJBContextImpl ctx = (EJBContextImpl) list.get(0);
if (ctx.getLastTimeUsed() <= allowedIdleTime) {
removeList.add(list.remove(0));
destroyedCount++;
} else {
break;
}
}
} else if (curSize < steadyPoolSize) {
//Need to populate....
if (maintainSteadySize == false) {
return;
}
if (resizeQuantity <= 0) {
populateCount = steadyPoolSize - curSize;
} else {
while ((curSize + populateCount) < steadyPoolSize) {
populateCount += resizeQuantity;
}
if ((curSize + populateCount) > maxPoolSize) {
populateCount -= (curSize + populateCount) - maxPoolSize;
}
}
}
}
if (removeList.size() > 0) {
int sz = removeList.size();
for (int i=0; i<sz; i++) {
try {
factory.destroy(removeList.get(i));
} catch (Throwable th) {
_logger.log(Level.FINE, "exception in doResize", th);
}
}
}
if (populateCount > 0) {
//preload adds items inside a sync block....
if(_logger.isLoggable(Level.FINE)) {
_logger.log(Level.FINE,
"[Pool-"+poolName+"]: Attempting to preload "
+ populateCount + " beans. CurSize/MaxPoolSize: "
+ list.size() + "/" + maxPoolSize);
}
preload(populateCount);
if(_logger.isLoggable(Level.FINE)) {
_logger.log(Level.FINE,
"[Pool-"+poolName+"]: After preload "
+ "CurSize/MaxPoolSize: "
+ list.size() + "/" + maxPoolSize);
}
}
} catch (Throwable th) {
_logger.log(Level.WARNING,
"[Pool-"+poolName+"]: Exception during reSize", th);
} finally {
if (enteredResizeBlock) {
synchronized (list) {
inResizing = false;
}
}
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;
}
});
}
}
long endTime = System.currentTimeMillis();
if(_logger.isLoggable(Level.FINE)) {
_logger.log(Level.FINE,
"[Pool-"+poolName+"]: Resize completed at: "
+ (new java.util.Date()) + "; after reSize: " +
getAllAttrValues());
_logger.log(Level.FINE, "[Pool-"+poolName+"]: Resize took: "
+ ((endTime-startTime)/1000.0) + " seconds.");
}
}
public String getAllAttrValues() {
StringBuffer sbuf = new StringBuffer("[Pool-"+poolName+"] ");
sbuf.append("CC=").append(createdCount).append("; ")
.append("DC=").append(destroyedCount).append("; ")
.append("CS=").append(list.size()).append("; ")
.append("SS=").append(steadyPoolSize).append("; ")
.append("MS=").append(maxPoolSize).append(";");
return sbuf.toString();
}
private class ReSizeWork
implements Servicable
{
public void prolog() {
}
public void service() {
run();
}
public void epilog() {
}
public void run() {
try {
doResize();
} catch (Exception ex) {
_logger.log(Level.WARNING,
"[Pool-"+poolName+"]: Exception during reSize", ex);
} finally {
synchronized (list) {
addedResizeTask = false;
}
}
}
}
private class IdleBeanWork
implements Servicable
{
public void prolog() {
}
public void service() {
run();
}
public void epilog() {
}
public void run() {
try {
doResize();
} catch (Exception ex) {
} finally {
addedIdleBeanWork = false;
}
}
}
private class PoolResizeTimerTask
extends java.util.TimerTask
{
Object lock;
PoolResizeTimerTask() {}
PoolResizeTimerTask(Object lock) {
this.lock = lock;
}
public void run() {
try {
if (addedIdleBeanWork == true) {
return;
}
IdleBeanWork work = new IdleBeanWork();
ContainerWorkPool.addLast(work);
addedIdleBeanWork = true;
} catch (Exception ex) {
_logger.log(Level.WARNING,
"[Pool-"+poolName+"]: Cannot perform "
+ " pool idle bean cleanup", ex);
}
}
} // End of class PoolResizeTimerTask
}
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