/**
* Copyright 2010 JBoss Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.drools.io.impl;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.Map.Entry;
import org.drools.ChangeSet;
import org.drools.SystemEventListener;
import org.drools.SystemEventListenerFactory;
import org.drools.io.Resource;
import org.drools.io.ResourceChangeNotifier;
import org.drools.io.ResourceChangeScanner;
import org.drools.io.ResourceChangeScannerConfiguration;
import org.drools.io.internal.InternalResource;
public class ResourceChangeScannerImpl
implements
ResourceChangeScanner {
private Map<Resource, Set<ResourceChangeNotifier>> resources;
private Set<Resource> directories;
private SystemEventListener listener;
private int interval;
public ResourceChangeScannerImpl() {
this.listener = SystemEventListenerFactory.getSystemEventListener();
this.resources = new HashMap<Resource, Set<ResourceChangeNotifier>>();
this.directories = new HashSet<Resource>();
this.setInterval( 60 );
this.listener.info( "ResourceChangeScanner created with default interval=60" );
}
public void setSystemEventListener(SystemEventListener listener) {
this.listener = listener;
}
public void configure(ResourceChangeScannerConfiguration configuration) {
this.setInterval( ((ResourceChangeScannerConfigurationImpl) configuration).getInterval() );
this.listener.info( "ResourceChangeScanner reconfigured with interval=" + getInterval() );
// restart it if it's already running.
if ( this.scannerScheduler != null && this.scannerScheduler.isRunning() ) {
stop();
start();
}
}
public ResourceChangeScannerConfiguration newResourceChangeScannerConfiguration() {
return new ResourceChangeScannerConfigurationImpl();
}
public ResourceChangeScannerConfiguration newResourceChangeScannerConfiguration(Properties properties) {
return new ResourceChangeScannerConfigurationImpl( properties );
}
public void subscribeNotifier(ResourceChangeNotifier notifier,
Resource resource) {
synchronized ( this.resources ) {
if ( ((InternalResource) resource).isDirectory() ) {
this.directories.add( resource );
}
Set<ResourceChangeNotifier> notifiers = this.resources.get( resource );
if ( notifiers == null ) {
notifiers = new HashSet<ResourceChangeNotifier>();
this.resources.put( resource,
notifiers );
}
this.listener.debug( "ResourceChangeScanner subcribing notifier=" + notifier + " to resource=" + resource );
notifiers.add( notifier );
}
}
public void unsubscribeNotifier(ResourceChangeNotifier notifier,
Resource resource) {
synchronized ( this.resources ) {
Set<ResourceChangeNotifier> notifiers = this.resources.get( resource );
if ( notifiers == null ) {
return;
}
this.listener.debug( "ResourceChangeScanner unsubcribing notifier=" + notifier + " to resource=" + resource );
notifiers.remove( notifier );
if ( notifiers.isEmpty() ) {
this.listener.debug( "ResourceChangeScanner resource=" + resource + " now has no subscribers" );
this.resources.remove( resource );
this.directories.remove( resource ); // don't bother with
// isDirectory check, as
// doing a remove is
// harmless if it doesn't
// exist
}
}
}
public Map<Resource, Set<ResourceChangeNotifier>> getResources() {
return resources;
}
public void scan() {
this.listener.debug( "ResourceChangeScanner attempt to scan " + this.resources.size() + " resources" );
synchronized ( this.resources ) {
Map<ResourceChangeNotifier, ChangeSet> notifications = new HashMap<ResourceChangeNotifier, ChangeSet>();
List<Resource> removed = new ArrayList<Resource>();
// detect modified and added
for ( Resource resource : this.directories ) {
this.listener.debug( "ResourceChangeScanner scanning directory=" + resource );
for ( Resource child : ((InternalResource) resource).listResources() ) {
if ( ((InternalResource) child).isDirectory() ) {
continue; // ignore sub directories
}
if ( !this.resources.containsKey( child ) ) {
this.listener.debug( "ResourceChangeScanner new resource=" + child );
// child is new
((InternalResource) child).setResourceType( ((InternalResource) resource).getResourceType() );
Set<ResourceChangeNotifier> notifiers = this.resources.get( resource ); // get notifiers for this
// directory
for ( ResourceChangeNotifier notifier : notifiers ) {
ChangeSetImpl changeSet = (ChangeSetImpl) notifications.get( notifier );
if ( changeSet == null ) {
// lazy initialise changeSet
changeSet = new ChangeSetImpl();
notifications.put( notifier,
changeSet );
}
if ( changeSet.getResourcesAdded().isEmpty() ) {
changeSet.setResourcesAdded( new ArrayList<Resource>() );
}
changeSet.getResourcesAdded().add( child );
notifier.subscribeChildResource( resource,
child );
}
}
}
}
for ( Entry<Resource, Set<ResourceChangeNotifier>> entry : this.resources.entrySet() ) {
Resource resource = entry.getKey();
Set<ResourceChangeNotifier> notifiers = entry.getValue();
if ( !((InternalResource) resource).isDirectory() ) {
// detect if Resource has been removed
long lastModified = ((InternalResource) resource).getLastModified();
long lastRead = ((InternalResource) resource).getLastRead();
if ( lastModified == 0 ) {
this.listener.debug( "ResourceChangeScanner removed resource=" + resource );
removed.add( resource );
// resource is no longer present
// iterate notifiers for this resource and add to each
// removed
for ( ResourceChangeNotifier notifier : notifiers ) {
ChangeSetImpl changeSet = (ChangeSetImpl) notifications.get( notifier );
if ( changeSet == null ) {
// lazy initialise changeSet
changeSet = new ChangeSetImpl();
notifications.put( notifier,
changeSet );
}
if ( changeSet.getResourcesRemoved().isEmpty() ) {
changeSet.setResourcesRemoved( new ArrayList<Resource>() );
}
changeSet.getResourcesRemoved().add( resource );
}
} else if ( lastRead < lastModified && lastRead >= 0 ) {
this.listener.debug( "ResourceChangeScanner modified resource=" + resource + " : " + lastRead + " : " + lastModified );
// it's modified
// iterate notifiers for this resource and add to each
// modified
for ( ResourceChangeNotifier notifier : notifiers ) {
ChangeSetImpl changeSet = (ChangeSetImpl) notifications.get( notifier );
if ( changeSet == null ) {
// lazy initialise changeSet
changeSet = new ChangeSetImpl();
notifications.put( notifier,
changeSet );
}
if ( changeSet.getResourcesModified().isEmpty() ) {
changeSet.setResourcesModified( new ArrayList<Resource>() );
}
changeSet.getResourcesModified().add( resource );
}
}
}
}
// now iterate and removed the removed resources, we do this so as
// not to mutate the foreach loop while iterating
for ( Resource resource : removed ) {
this.resources.remove( resource );
}
for ( Entry<ResourceChangeNotifier, ChangeSet> entry : notifications.entrySet() ) {
ResourceChangeNotifier notifier = entry.getKey();
ChangeSet changeSet = entry.getValue();
notifier.publishChangeSet( changeSet );
}
}
}
public void setInterval(int interval) {
if ( interval <= 0 ) {
throw new IllegalArgumentException( "Invalid interval time: " + interval + ". It should be a positive number bigger than 0" );
}
this.interval = interval;
this.listener.info( "ResourceChangeScanner reconfigured with interval=" + getInterval() );
if ( this.scannerScheduler != null && this.scannerScheduler.isRunning() ) {
stop();
start();
}
}
public int getInterval() {
return this.interval;
}
public void start() {
this.scannerScheduler = new ProcessChangeSet( this.resources,
this,
this.listener,
this.interval );
thread = new Thread( this.scannerScheduler );
thread.start();
}
public void stop() {
if ( this.scannerScheduler != null && this.scannerScheduler.isRunning() ) {
this.scannerScheduler.stop();
this.thread.interrupt();
this.scannerScheduler = null;
}
}
public void reset() {
this.resources.clear();
this.directories.clear();
}
private Thread thread;
private ProcessChangeSet scannerScheduler;
public static class ProcessChangeSet
implements
Runnable {
private volatile boolean scan;
private ResourceChangeScannerImpl scanner;
private long interval;
private Map<Resource, Set<ResourceChangeNotifier>> resources;
private SystemEventListener listener;
ProcessChangeSet(Map<Resource, Set<ResourceChangeNotifier>> resources,
ResourceChangeScannerImpl scanner,
SystemEventListener listener,
int interval) {
this.resources = resources;
this.scanner = scanner;
this.listener = listener;
this.interval = interval;
this.scan = true;
}
public int getInterval() {
return (int) this.interval;
}
public void stop() {
this.scan = false;
}
public boolean isRunning() {
return this.scan;
}
public void run() {
synchronized ( this ) {
if ( this.scan ) {
this.listener.info( "ResourceChangeNotification scanner has started" );
}
while ( this.scan ) {
Exception exception = null;
// System.out.println( "BEFORE : sync this.resources" );
synchronized ( this.resources ) {
// System.out.println( "DURING : sync this.resources" );
// lock the resources, as we don't want this modified
// while processing
this.scanner.scan();
}
// System.out.println( "AFTER : SCAN" );
try {
this.listener.debug( "ResourceChangeScanner thread is waiting for " + this.interval + " seconds." );
wait( this.interval * 1000 );
} catch ( InterruptedException e ) {
exception = e;
}
if ( this.scan && exception != null ) {
this.listener.exception( new RuntimeException( "ResourceChangeNotification ChangeSet scanning thread was interrupted, but shutdown was not requested",
exception ) );
}
}
this.listener.info( "ResourceChangeNotification scanner has stopped" );
}
}
}
}