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package com.sun.enterprise.resource;
import javax.transaction.Transaction;
/**
* this resource pool does not allow sharing
* A resource is only given out if it is not used by
* any enterprise bean and it does not have any pending transaction
*
* @author Aditya Gore
*/
public class AssocWithThreadResourcePool extends AbstractResourcePool {
private static ThreadLocal<ResourceHandle> localResource =
new ThreadLocal<ResourceHandle>();
public AssocWithThreadResourcePool( String poolName )
throws PoolingException{
super( poolName );
}
protected ResourceHandle prefetch( ResourceSpec spec,
ResourceAllocator alloc, Transaction tran)
{
ResourceHandle ar = localResource.get();
if (ar != null) {
//synch on ar and do a quick-n-dirty check to see if the local
//resource is usable at all
synchronized( ar.lock ) {
if ( (ar.getThreadId() != Thread.currentThread().getId()) ||
ar.hasConnectionErrorOccurred() ||
ar.isDirty() || !ar.isAssociated() ) {
//we were associated with someone else or resource error
//occurred or resource was disassociated and used by some one else. So evict
//NOTE: We do not setAssociated to false here since someone
//else has associated this resource to themself. Also, if
//the eviction is because of a resourceError, the resource is
//not going to be used anyway.
localResource.remove();
return null;
}
if (ar.getResourceState().isFree() &&
ar.getResourceState().isUnenlisted()) {
if (matchConnections) {
if (! alloc.matchConnection( ar ) ) {
//again, since the credentials of the caller don't match
//evict from ThreadLocal
//also, mark the resource as unassociated and make this resource
//potentially usable
localResource.remove();
ar.setAssociated( false );
if ( monitoringEnabled ) {
poolCounters.incrementNumConnNotSuccessfullyMatched();
}
return null;
}
if (monitoringEnabled) {
poolCounters.incrementNumConnSuccessfullyMatched();
}
}
setResourceStateToBusy(ar);
if(maxConnectionUsage_ > 0){
ar.incrementUsageCount();
}
return ar;
}
}
}
return null;
}
private void setInThreadLocal(ResourceHandle h) {
if (h != null) {
synchronized (h.lock) {
h.setThreadId(Thread.currentThread().getId());
h.setAssociated(true);
localResource.set(h);
}
}
}
protected boolean isResourceUnused(ResourceHandle h){
return h.getResourceState().isFree() && !h.isAssociated() ;
}
// this is the RI getResource() with some modifications
/**
* return resource in free list. If none is found, returns null
*
*/
protected ResourceHandle getUnenlistedResource(ResourceSpec spec,
ResourceAllocator alloc, Transaction tran) throws PoolingException {
ResourceHandle result;
result = super.getUnenlistedResource(spec, alloc, tran);
//If we came here, that's because free doesn't have anything
//to offer us. This could be because:
//1. All free resources are associated
//2. There are no free resources
//3. We cannot create anymore free resources
//Handle case 1 here
//DISASSOCIATE
if (result == null) {
synchronized (this) {
for (ResourceHandle resource : resources) {
synchronized (resource.lock) {
//though we are checking resources from within the free list,
//we could have a situation where the resource was free upto
//this point, put just before we entered the synchronized block,
//the resource "h" got used by the thread that was associating it
//so we need to check for isFree also
if (resource.getResourceState().isUnenlisted() &&
resource.getResourceState().isFree()) {
if (!matchConnection(resource, alloc)) {
continue;
}
if (resource.hasConnectionErrorOccurred()) {
continue;
}
result = resource;
setResourceStateToBusy(result);
result.setAssociated(false);
break;
}
}
}
}
}
if (localResource.get() == null) {
setInThreadLocal(result);
}
return result;
}
protected synchronized void freeUnenlistedResource(ResourceHandle h) {
if ( ! h.isAssociated() ) {
free.add( h );
}
//update monitoring data
if(monitoringEnabled){
poolCounters.decrementNumConnUsed(false);
}
if (maxConnectionUsage_ > 0) {
performMaxConnectionUsageOperation(h);
}
notifyWaitingThreads();
}
protected void destroyResource(ResourceHandle resourceHandle) {
try {
super.destroyResource( resourceHandle );
} finally {
//Note: here we are using the connectionErrorOccurred flag to indicate
//that this resource is no longer usable. This flag would be checked while
//getting from ThreadLocal
//The main intention of marking this is to handle the case where
//failAllConnections happens
//Note that setDirty only happens here - i.e during destroying of a
//resource
synchronized( resourceHandle.lock ) {
resourceHandle.setDirty();
}
}
}
}
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