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Core services for Usergrid system.

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/*******************************************************************************
 * Copyright 2012 Apigee Corporation
 * 
 * Licensed 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.usergrid.locking.cassandra;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import me.prettyprint.hector.api.locking.HLock;
import me.prettyprint.hector.api.locking.HLockManager;
import me.prettyprint.hector.api.locking.HLockTimeoutException;

import org.usergrid.locking.Lock;
import org.usergrid.locking.exception.UGLockException;

/**
 * @author tnine
 *
 */
public class HectorLockImpl implements Lock {

  private HLock lock;
  private HLockManager lm;
  private AtomicInteger count = new AtomicInteger();
  
  /**
   * 
   */
  public HectorLockImpl(HLock lock, HLockManager lm) {
    this.lock = lock;
    this.lm = lm;
  }

  /* (non-Javadoc)
   * @see org.usergrid.locking.Lock#acquire(long, java.util.concurrent.TimeUnit)
   */
  @Override
  public boolean tryLock(long timeout, TimeUnit time) throws UGLockException {
    try{
      lm.acquire(this.lock, time.toMillis(timeout));
      count.incrementAndGet();
    }catch(HLockTimeoutException hlte){
     return false;
    }
    
    return true;
  }

  /* (non-Javadoc)
   * @see org.usergrid.locking.Lock#lock()
   */
  @Override
  public void lock() throws UGLockException {
    lm.acquire(lock);
    count.incrementAndGet();
  }

  /* (non-Javadoc)
   * @see org.usergrid.locking.Lock#release()
   */
  @Override
  public void unlock() throws UGLockException {
   int current =  count.decrementAndGet();
    
    if(current == 0){
      lm.release(this.lock);
    }
    
  }

}