modules/gemfire-modules/src/main/java/com/gemstone/gemfire/modules/session/catalina/JvmRouteBinderValve.java

/*=========================================================================
 * Copyright (c) 2010-2014 Pivotal Software, Inc. All Rights Reserved.
 * This product is protected by U.S. and international copyright
 * and intellectual property laws. Pivotal products are covered by
 * one or more patents listed at http://www.pivotal.io/patents.
 *=========================================================================
 */
package com.gemstone.gemfire.modules.session.catalina;

import java.io.IOException;

import javax.servlet.ServletException;

import org.apache.catalina.Manager;
import org.apache.catalina.Session;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.valves.ValveBase;

public class JvmRouteBinderValve extends ValveBase {
  
  protected static final String info = "com.gemstone.gemfire.modules.session.JvmRouteBinderValve/1.0";

  @Override
  public void invoke(Request request, Response response) throws IOException,
      ServletException {
    
    // Get the Manager
    Manager manager = request.getContext().getManager();

    // If it is an AbstractManager, handle possible failover
    if (manager instanceof DeltaSessionManager) {
      DeltaSessionManager absMgr = (DeltaSessionManager) manager;
      String localJvmRoute = absMgr.getJvmRoute();
        if (localJvmRoute != null) {
          handlePossibleFailover(request, absMgr,localJvmRoute);
        }
    }

    // Invoke the next Valve
    getNext().invoke(request, response);
  }
  
  private void handlePossibleFailover(Request request, DeltaSessionManager manager, String localJvmRoute) {
    String sessionId = request.getRequestedSessionId();
    if (sessionId != null) {
      // Get request JVM route
      String requestJvmRoute = null;
      int index = sessionId.indexOf(".");
      if (index > 0) {
        requestJvmRoute = sessionId.substring(index + 1, sessionId.length());
      }

      // If the requested JVM route doesn't equal the session's JVM route, handle failover
      if (requestJvmRoute != null && !requestJvmRoute.equals(localJvmRoute)) {
        if (manager.getLogger().isDebugEnabled()) {
          StringBuilder builder = new StringBuilder();
          builder
            .append(this)
            .append(": Handling failover of session ")
            .append(sessionId)
            .append(" from ")
            .append(requestJvmRoute)
            .append(" to ")
            .append(localJvmRoute);
          manager.getLogger().debug(builder.toString());
        }
        // Get the original session
        Session session = null;
        try {
          session = manager.findSession(sessionId);
        } catch (IOException e) {
          StringBuilder builder = new StringBuilder();
          builder
            .append(this)
            .append(": Caught exception attempting to find session ")
            .append(sessionId)
            .append(" in ")
            .append(manager);
          manager.getLogger().warn(builder.toString(), e);
        }
        
        if (session == null) {
          StringBuilder builder = new StringBuilder();
          builder
            .append(this)
            .append(": Did not find session ")
            .append(sessionId)
            .append(" to failover in ")
            .append(manager);
          manager.getLogger().warn(builder.toString());
        } else {
          // Change its session id. This removes the previous session and creates the new one.
          String baseSessionId = sessionId.substring(0, index);
          String newSessionId = baseSessionId + "." + localJvmRoute;
          session.setId(newSessionId);
  
          // Change the request's session id
          request.changeSessionId(newSessionId);
        }
      }
    }
  }
}