bundles/org.eclipse.rap.rwt.supplemental.fileupload/src/org/eclipse/rap/rwt/supplemental/fileupload/internal/FileUploadHandlerStore.java

/*******************************************************************************
 * Copyright (c) 2011 EclipseSource and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    EclipseSource - initial API and implementation
 ******************************************************************************/
package org.eclipse.rap.rwt.supplemental.fileupload.internal;

import java.util.HashMap;
import java.util.Map;

import org.apache.commons.io.FileCleaningTracker;
import org.eclipse.rap.rwt.supplemental.fileupload.FileUploadHandler;
import org.eclipse.rwt.RWT;
import org.eclipse.rwt.service.SessionStoreEvent;
import org.eclipse.rwt.service.SessionStoreListener;


public final class FileUploadHandlerStore {

  private static final String ATTR_NAME = FileUploadHandlerStore.class.getName() + ".instance";
  private static final String CLEANING_TRACKER_ATTR_NAME = FileCleaningTracker.class.getName() + ".fileupload";  

  private static final Object LOCK = new Object();
  private final Map< String, FileUploadHandler > handlers;
  private final Object lock;
  private boolean registered;

  private FileUploadHandlerStore() {
    handlers = new HashMap< String, FileUploadHandler >();
    lock = new Object();
  }

  public static FileUploadHandlerStore getInstance() {
    FileUploadHandlerStore result;
    synchronized( LOCK ) {
      result = ( FileUploadHandlerStore )RWT.getApplicationStore().getAttribute( ATTR_NAME );
      if( result == null ) {
        result = new FileUploadHandlerStore();
        RWT.getApplicationStore().setAttribute( ATTR_NAME, result );        
      }
    }
    return result;
  }

  public void registerHandler( String token, FileUploadHandler fileUploadHandler ) {
    ensureServiceHandler();
    synchronized( lock ) {
      handlers.put( token, fileUploadHandler );
    }
  }

  public void deregisterHandler( String token ) {
    synchronized( lock ) {
      handlers.remove( token );
    }
  }

  public FileUploadHandler getHandler( String token ) {
    FileUploadHandler result;
    synchronized( lock ) {
      result = handlers.get( token );
    }
    return result;
  }

  public static String createToken() {
    int random1 = ( int )( Math.random() * 0xfffffff );
    int random2 = ( int )( Math.random() * 0xfffffff );
    return Integer.toHexString( random1 ) + Integer.toHexString( random2 );
  }

  private void ensureServiceHandler() {
    synchronized( lock ) {
      if( !registered ) {
        RWT.getServiceManager().registerServiceHandler( FileUploadServiceHandler.SERVICE_HANDLER_ID,
                                                        new FileUploadServiceHandler() );
        registered = true;
      }
    }
  }
  
  public static FileCleaningTracker getCleaningTracker() {    
      FileCleaningTracker cleaningTracker = ( FileCleaningTracker )RWT.getSessionStore().getAttribute( CLEANING_TRACKER_ATTR_NAME );
      if ( cleaningTracker == null ) {        
        // Create cleaning tracker for current session and register session listener that will destroy it 
        cleaningTracker = new FileCleaningTracker();
        RWT.getSessionStore().setAttribute( CLEANING_TRACKER_ATTR_NAME, cleaningTracker );
        RWT.getSessionStore().addSessionStoreListener( new FileUploadCleanupHandler() );
      }
      return cleaningTracker;
  }
  
  private static class FileUploadCleanupHandler implements SessionStoreListener {
    public void beforeDestroy( SessionStoreEvent event ) {
      // Destroy the 
      FileCleaningTracker cleaningTracker = ( FileCleaningTracker ) RWT.getSessionStore().getAttribute( CLEANING_TRACKER_ATTR_NAME );
      RWT.getSessionStore().removeAttribute( CLEANING_TRACKER_ATTR_NAME );
      cleaningTracker.exitWhenFinished();
    }
  }
}