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package com.sun.enterprise.resource.pool.datastructure;
import com.sun.enterprise.resource.allocator.ResourceAllocator;
import com.sun.enterprise.resource.ResourceHandle;
import com.sun.enterprise.resource.pool.ResourceHandler;
import com.sun.enterprise.resource.pool.datastructure.strategy.ResourceSelectionStrategy;
import com.sun.appserv.connectors.internal.api.PoolingException;
import com.sun.logging.LogDomains;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.Iterator;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* ReadWriteLock based datastructure for pool
* @author Jagadish Ramu
*/
public class RWLockDataStructure implements DataStructure {
private ResourceHandler handler;
private ResourceSelectionStrategy strategy;
private int maxSize;
private final ArrayList<ResourceHandle> resources;
private ReentrantReadWriteLock reentrantLock = new ReentrantReadWriteLock();
private ReentrantReadWriteLock.ReadLock readLock = reentrantLock.readLock();
private ReentrantReadWriteLock.WriteLock writeLock = reentrantLock.writeLock();
protected final static Logger _logger =
LogDomains.getLogger(RWLockDataStructure.class,LogDomains.RSR_LOGGER);
public RWLockDataStructure(String parameters, int maxSize,
ResourceHandler handler, String strategyClass) {
resources = new ArrayList<ResourceHandle>((maxSize > 1000) ? 1000 : maxSize);
this.maxSize = maxSize;
this.handler = handler;
initializeStrategy(strategyClass);
if(_logger.isLoggable(Level.FINEST)) {
_logger.log(Level.FINEST, "pool.datastructure.rwlockds.init");
}
}
private void initializeStrategy(String strategyClass) {
//TODO
}
/**
* {@inheritDoc}
*/
public int addResource(ResourceAllocator allocator, int count) throws PoolingException {
int numResAdded = 0;
writeLock.lock();
//for now, coarser lock. finer lock needs "resources.size() < maxSize()" once more.
try {
for (int i = 0; i < count && resources.size() < maxSize; i++) {
ResourceHandle handle = handler.createResource(allocator);
resources.add(handle);
numResAdded++;
}
} catch (Exception e) {
PoolingException pe = new PoolingException(e.getMessage());
pe.initCause(e);
throw pe;
} finally {
writeLock.unlock();
}
return numResAdded;
}
/**
* {@inheritDoc}
*/
public ResourceHandle getResource() {
readLock.lock();
for(int i=0; i<resources.size(); i++){
ResourceHandle h = resources.get(i);
if (!h.isBusy()) {
readLock.unlock();
writeLock.lock();
try {
if (!h.isBusy()) {
h.setBusy(true);
return h;
} else {
readLock.lock();
continue;
}
}finally {
writeLock.unlock();
}
} else {
continue;
}
}
readLock.unlock();
return null;
}
/**
* {@inheritDoc}
*/
public void removeResource(ResourceHandle resource) {
boolean removed = false;
writeLock.lock();
try {
removed = resources.remove(resource);
} finally {
writeLock.unlock();
}
if(removed) {
handler.deleteResource(resource);
}
}
/**
* {@inheritDoc}
*/
public void returnResource(ResourceHandle resource) {
writeLock.lock();
try{
resource.setBusy(false);
}finally{
writeLock.unlock();
}
}
/**
* {@inheritDoc}
*/
public int getFreeListSize() {
//inefficient implementation.
int free = 0;
readLock.lock();
try{
Iterator it = resources.iterator();
while (it.hasNext()) {
ResourceHandle rh = (ResourceHandle)it.next();
if(!rh.isBusy()){
free++;
}
}
}finally{
readLock.unlock();
}
return free;
}
/**
* {@inheritDoc}
*/
public void removeAll() {
writeLock.lock();
try {
Iterator it = resources.iterator();
while (it.hasNext()) {
handler.deleteResource((ResourceHandle) it.next());
it.remove();
}
} finally {
writeLock.unlock();
}
resources.clear();
}
/**
* {@inheritDoc}
*/
public int getResourcesSize() {
return resources.size();
}
/**
* Set maxSize based on the new max pool size set on the connection pool
* during a reconfiguration.
*
* @param maxSize
*/
public void setMaxSize(int maxSize) {
this.maxSize = maxSize;
}
@Override
public ArrayList<ResourceHandle> getAllResources() {
throw new UnsupportedOperationException("Not supported yet.");
}
}