PentahoSessionHolder.java

/*
 * This program is free software; you can redistribute it and/or modify it under the 
 * terms of the GNU General Public License, version 2 as published by the Free Software 
 * Foundation.
 *
 * You should have received a copy of the GNU General Public License along with this 
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/gpl-2.0.html 
 * or from the Free Software Foundation, Inc., 
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 *
 * Copyright 2005 - 2008 Pentaho Corporation.  All rights reserved. 
 * 
 * @created Jun 23, 2005 
 * @author James Dixon
 * 
 */
package org.pentaho.platform.engine.core.system;

import java.lang.reflect.Constructor;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.pentaho.platform.api.engine.IPentahoSession;

/**
 * Stores the IPentahoSession session object for the current thread so that a
 * web service bean can get to it without requiring it to be passed to its
 * methods.
 * 
 * <p>
 * Configure using system property {@code pentaho.sessionHolder.strategy} or {@link #setStrategyName(String)}. Valid 
 * values are: {@code MODE_INHERITABLETHREADLOCAL} and {@code MODE_GLOBAL}.
 * </p>
 * 
 * <p>Partially inspired by {@code org.springframework.security.context.SecurityContextHolder}.</p>
 * 
 * @author jamesdixon
 * @author mlowery (modifications to support global)
 */
public class PentahoSessionHolder {

  // ~ Static fields/initializers ======================================================================================

  private static final Log logger = LogFactory.getLog(PentahoSessionHolder.class);

  public static final String MODE_INHERITABLETHREADLOCAL = "MODE_INHERITABLETHREADLOCAL"; //$NON-NLS-1$

  public static final String MODE_GLOBAL = "MODE_GLOBAL"; //$NON-NLS-1$

  public static final String SYSTEM_PROPERTY = "pentaho.sessionHolder.strategy"; //$NON-NLS-1$

  private static String strategyName = System.getProperty(SYSTEM_PROPERTY);

  private static IPentahoSessionHolderStrategy strategy;

  static {
    initialize();
  }

  // ~ Instance fields =================================================================================================

  // ~ Constructors ====================================================================================================

  public PentahoSessionHolder() {
    super();
  }

  // ~ Methods =========================================================================================================

  /**
   * Sets an IPentahoSession for the current thread
   * @param session
   */
  public static void setSession(IPentahoSession session) {
    strategy.setSession(session);
  }

  /**
   * Returns the IPentahoSession for the current thread
   * @return thread session
   */
  public static IPentahoSession getSession() {
    return strategy.getSession();
  }

  /**
   * Removes the IPentahoSession for the current thread.
   * It is important that the framework calls this to prevent session bleed-
   * through between requests as threads are re-used by the server.
   */
  public static void removeSession() {
    strategy.removeSession();
  }

  private static void initialize() {
    if ((strategyName == null) || "".equals(strategyName)) { //$NON-NLS-1$
      strategyName = MODE_INHERITABLETHREADLOCAL;
    }

    if (strategyName.equals(MODE_INHERITABLETHREADLOCAL)) {
      strategy = new InheritableThreadLocalPentahoSessionHolderStrategy();
    } else if (strategyName.equals(MODE_GLOBAL)) {
      strategy = new GlobalPentahoSessionHolderStrategy();
    } else {
      // Try to load a custom strategy
      try {
        Class clazz = Class.forName(strategyName);
        Constructor customStrategy = clazz.getConstructor(new Class[] {});
        strategy = (IPentahoSessionHolderStrategy) customStrategy.newInstance(new Object[] {});
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }

    logger.debug("PentahoSessionHolder initialized: strategy=" + strategyName);

  }

  public static void setStrategyName(final String strategyName) {
    PentahoSessionHolder.strategyName = strategyName;
    initialize();
  }
}