/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2009, Red Hat Middleware LLC, and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.jboss.ha.framework.server.lock;

import java.io.Serializable;
import java.util.concurrent.atomic.AtomicReference;

import org.jboss.ha.framework.interfaces.ClusterNode;

/**
 * 
 * @author Brian Stansberry
 * 
 * @version $Revision:$
 */
public class ClusterLockState
{
   /** Lock status of a category */
   public enum State 
   { 
      /** No one has the lock and local node is not attempting to acquire */
      UNLOCKED,
      /** Local node is attempting to acquire lock across cluster */
      REMOTE_LOCKING,
      /** Local node has lock across cluster, now attempting locally */
      LOCAL_LOCKING,
      /** The lock is held locally */
      LOCKED,
      /** 
       * This object has been removed from the categories map and 
       * should be discarded
       */
      INVALID  
   }
   final Serializable lockId;
   final AtomicReference<ClusterLockState.State> state = new AtomicReference<ClusterLockState.State>(State.UNLOCKED);
   ClusterNode holder;
   
   ClusterLockState(Serializable lockId)
   {
      if (lockId == null)
      { 
         throw new IllegalArgumentException("lockId is null");            
      }
      this.lockId = lockId;
   }
   
   public synchronized ClusterNode getHolder()
   {
      return holder;
   }
   
   public synchronized void invalidate()
   {
      this.state.set(State.INVALID);
      this.holder = null;
   }
   
   public synchronized void lock(ClusterNode holder)
   {
      this.state.set(State.LOCKED);
      this.holder = holder;
   }
   
   public synchronized void release()
   {
      if (this.state.compareAndSet(State.LOCKED, State.UNLOCKED))
      {
         this.holder = null;
      }
   }
}