/*

  * Copyright 2007 The Kuali Foundation

  *

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  *

  * 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.kuali.rice.ksb.messaging.threadpool;

 import org.apache.log4j.Logger;

 import org.kuali.rice.core.config.Config;

 import org.kuali.rice.core.config.ConfigContext;

 import org.kuali.rice.core.util.ClassLoaderUtils;

 import java.util.concurrent.Executors;

 import java.util.concurrent.PriorityBlockingQueue;

 import java.util.concurrent.ThreadFactory;

 import java.util.concurrent.ThreadPoolExecutor;

 import java.util.concurrent.TimeUnit;

 /**

  * A Thread Pool implementation for the KSB which implements a thread pool backed by a configuration store.

  *

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class KSBThreadPoolImpl extends ThreadPoolExecutor implements KSBThreadPool {

     private static final Logger LOG = Logger.getLogger(KSBThreadPoolImpl.class);

     public static final int DEFAULT_POOL_SIZE = 5;

     private boolean started;

     private boolean poolSizeSet;

     public KSBThreadPoolImpl() {

             super(DEFAULT_POOL_SIZE, DEFAULT_POOL_SIZE, 60, TimeUnit.SECONDS, new PriorityBlockingQueue(1, new PriorityBlockingQueuePersistedMessageComparator()),  new KSBThreadFactory(ClassLoaderUtils.getDefaultClassLoader()), new ThreadPoolExecutor.AbortPolicy());

     }

     public void setCorePoolSize(int corePoolSize) {

                 LOG.info("Setting core pool size to " + corePoolSize + " threads.");

                 super.setCorePoolSize(corePoolSize);

                 this.poolSizeSet = true;

     }

     public long getKeepAliveTime() {

         return super.getKeepAliveTime(TimeUnit.MILLISECONDS);

     }

     public boolean isStarted() {

         return this.started;

     }

     public void start() throws Exception {

             LOG.info("Starting the KSB thread pool...");

             loadSettings();

             this.started = true;

             LOG.info("...KSB thread pool successfully started.");

     }

     public void stop() throws Exception {

                 if (isStarted()) {

                         LOG.info("Shutting down KSB thread pool...");

                     this.shutdownNow();

                     this.started = false;

                     LOG.info("...KSB thread pool successfully shut down.");

                 }

     }

     /**

          * Loads the thread pool settings from the DAO.

          */

     protected void loadSettings() {

                 String threadPoolSizeStr = ConfigContext.getCurrentContextConfig().getProperty(Config.THREAD_POOL_SIZE);        

                 if (!this.poolSizeSet) {

                     int poolSize = DEFAULT_POOL_SIZE;

                     try {

                             poolSize = new Integer(threadPoolSizeStr);

                     } catch (NumberFormatException nfe) {

                             LOG.error( "loadSettings(): Unable to parse the pool size: '"+threadPoolSizeStr+"'");

                     }

                     setCorePoolSize(poolSize);

                 }

     }

     public Object getInstance() {

             return this;

     }

     /**

          * A simple ThreadFactory which names the thread as follows:<br>

          * <br>

          *

          * <i>serviceNamespace</i>/KSB-pool-<i>m</i>-thread-<i>n</i><br>

          * <br>

          *

          * Where <i>serviceNamespace</i> is the service namespace of the application running the thread pool, <i>m</i> is the

          * sequence number of the factory and <i>n</i> is the sequence number of the thread within the factory.

          *

  * @author Kuali Rice Team (rice.collab@kuali.org)

          */

     private static class KSBThreadFactory implements ThreadFactory {

         private static int factorySequence = 0;

         private static int threadSequence = 0;

         private ThreadFactory defaultThreadFactory = Executors.defaultThreadFactory();

         private ClassLoader contextClassLoader;

         public KSBThreadFactory(ClassLoader contextClassLoader) {

             this.contextClassLoader = contextClassLoader;

             factorySequence++;

         }

         public Thread newThread(Runnable runnable) {

             threadSequence++;

             Thread thread = this.defaultThreadFactory.newThread(runnable);

             // if the thread ends up getting spawned by an action inside of a workflow plugin or something along those lines, it will inherit the plugin's

             // classloader as it's ContextClassLoader.  Let's make sure it's set to the same ClassLoader that loaded the KSBConfigurer

             thread.setContextClassLoader(contextClassLoader);

             thread.setName(ConfigContext.getCurrentContextConfig().getServiceNamespace() + "/KSB-pool-" + factorySequence + "-thread-"

                     + threadSequence);

             return thread;

         }

     }

 }