content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF licenses this file
   *  to you 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.apache.causeway.persistence.jdo.spring.support;
  
  import javax.jdo.PersistenceManager;
  import javax.jdo.PersistenceManagerFactory;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.springframework.dao.DataAccessException;
  import org.springframework.transaction.support.TransactionSynchronizationManager;
  import org.springframework.ui.ModelMap;
  import org.springframework.web.context.request.WebRequest;
  import org.springframework.web.context.request.WebRequestInterceptor;
  
  import org.apache.causeway.persistence.jdo.spring.integration.PersistenceManagerFactoryUtils;
  import org.apache.causeway.persistence.jdo.spring.integration.PersistenceManagerHolder;
  
  /**
   * Spring web request interceptor that binds a JDO PersistenceManager to the
   * thread for the entire processing of the request. Intended for the "Open
   * PersistenceManager in View" pattern, i.e. to allow for lazy loading in
   * web views despite the original transactions already being completed.
   *
   * <p>This interceptor makes JDO PersistenceManagers available via the current thread,
   * which will be autodetected by transaction managers. It is suitable for service
   * layer transactions via {@link org.apache.causeway.persistence.jdo.spring.integration.JdoTransactionManager}
   * or {@link org.springframework.transaction.jta.JtaTransactionManager} as well
   * as for non-transactional read-only execution.
   *
   * <p>In contrast to {@link OpenPersistenceManagerInViewFilter}, this interceptor
   * is set up in a Spring application context and can thus take advantage of
   * bean wiring.
   *
   * @see OpenPersistenceManagerInViewFilter
   * @see org.apache.causeway.persistence.jdo.spring.integration.JdoTransactionManager
   * @see org.apache.causeway.persistence.jdo.spring.integration.PersistenceManagerFactoryUtils#getPersistenceManager
   * @see org.springframework.transaction.support.TransactionSynchronizationManager
   */
  public class OpenPersistenceManagerInViewInterceptor implements WebRequestInterceptor {
  
  	/**
  	 * Suffix that gets appended to the PersistenceManagerFactory toString
  	 * representation for the "participate in existing persistence manager
  	 * handling" request attribute.
  	 * @see #getParticipateAttributeName
  	 */
  	public static final String PARTICIPATE_SUFFIX = ".PARTICIPATE";
  
  	protected final Log logger = LogFactory.getLog(getClass());
  
  	private PersistenceManagerFactory persistenceManagerFactory;
  
  	/**
  	 * Set the JDO PersistenceManagerFactory that should be used to create
  	 * PersistenceManagers.
  	 */
  	public void setPersistenceManagerFactory(PersistenceManagerFactory pmf) {
  		this.persistenceManagerFactory = pmf;
  	}
  
  	/**
  	 * Return the JDO PersistenceManagerFactory that should be used to create
  	 * PersistenceManagers.
  	 */
  	public PersistenceManagerFactory getPersistenceManagerFactory() {
  		return persistenceManagerFactory;
  	}
  
  	@Override
  	public void preHandle(WebRequest request) throws DataAccessException {
  		if (TransactionSynchronizationManager.hasResource(getPersistenceManagerFactory())) {
  			// Do not modify the PersistenceManager: just mark the request accordingly.
  			String participateAttributeName = getParticipateAttributeName();
  			Integer count = (Integer) request.getAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST);
  			int newCount = (count != null ? count + 1 : 1);
  			request.setAttribute(getParticipateAttributeName(), newCount, WebRequest.SCOPE_REQUEST);
  		}
  		else {
  			logger.debug("Opening JDO PersistenceManager in OpenPersistenceManagerInViewInterceptor");
  			PersistenceManager pm =
  					PersistenceManagerFactoryUtils.getPersistenceManager(getPersistenceManagerFactory(), true);
  			TransactionSynchronizationManager.bindResource(
  					getPersistenceManagerFactory(), new PersistenceManagerHolder(pm));
  		}
  	}
  
  	@Override
  	public void postHandle(WebRequest request, ModelMap model) {
  	}
  
  	@Override
  	public void afterCompletion(WebRequest request, Exception ex) throws DataAccessException {
  		String participateAttributeName = getParticipateAttributeName();
  		Integer count = (Integer) request.getAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST);
  		if (count != null) {
  			// Do not modify the PersistenceManager: just clear the marker.
  			if (count > 1) {
  				request.setAttribute(participateAttributeName, count - 1, WebRequest.SCOPE_REQUEST);
  			}
  			else {
  				request.removeAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST);
  			}
  		}
  		else {
  			PersistenceManagerHolder pmHolder = (PersistenceManagerHolder)
  					TransactionSynchronizationManager.unbindResource(getPersistenceManagerFactory());
  			logger.debug("Closing JDO PersistenceManager in OpenPersistenceManagerInViewInterceptor");
  			PersistenceManagerFactoryUtils.releasePersistenceManager(
  					pmHolder.getPersistenceManager(), getPersistenceManagerFactory());
  		}
  	}
  
  	/**
  	 * Return the name of the request attribute that identifies that a request is
  	 * already filtered. Default implementation takes the toString representation
  	 * of the PersistenceManagerFactory instance and appends ".FILTERED".
  	 * @see #PARTICIPATE_SUFFIX
  	 */
  	protected String getParticipateAttributeName() {
  		return getPersistenceManagerFactory().toString() + PARTICIPATE_SUFFIX;
  	}
  
  }
  