/*
    * 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.river.outrigger;
  
  import java.util.LinkedList;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  import net.jini.id.Uuid;
  
  /**
   * Logs expiration of leases and asynchronously persists them to disk.
   */
  class ExpirationOpQueue extends Thread {
      /** The queue of expirations to log */
      private final LinkedList queue = new LinkedList();
  
      /** The server we are working for */
      private final OutriggerServerImpl server;
  
      /** Logger for logging exceptions */
      private static final Logger logger = 
  	Logger.getLogger(OutriggerServerImpl.leaseLoggerName);
  
      /**
       * Create a new <code>ExpirationOpQueue</code> that
       * will handle lease expiration logging for the 
       * specified server.
       * @param server the <code>OutriggerServerImpl</code> to 
       *        log for.
       */
      ExpirationOpQueue(OutriggerServerImpl server) {
  	super("Expiration Op Queue");
  	this.server = server;
      }
  
      /**
       * Enqueue the logging of the expiration of the specified lease.
       * @param cookie The cookie of the lease that has expired.
       */
      synchronized void enqueue(Uuid cookie) {
  	queue.add(cookie);
  	notifyAll();
      }
  
      /**
       * Stop the queue
       */
      void terminate() {
          interrupt();
          synchronized (this){
  	notifyAll();
      }
      }
  
      public void run() {
  	while (!Thread.currentThread().isInterrupted()) { // ok not to lock since it starts false
  	    try {
  		final Uuid cookie;
  		synchronized (this) { 
  		    while (queue.isEmpty()) {
  			wait();
  		    }
  		    cookie = (Uuid)queue.removeFirst();
  		}
  		
  		server.cancelOp(cookie, true);
  	    } catch (InterruptedException e){
                  Thread.currentThread().interrupt(); // restore
                  return;
  	    } catch (Throwable t) {
  		try {
  		    logger.log(Level.INFO,
  			       "ExpirationOpQueue.run encountered " +
  			           t.getClass().getName() + ", continuing", 
  			       t);
  		} catch (Throwable tt) {
  		    // don't let a problem in logging kill the thread
  		}
  	    }
  	}
      }
  }