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Core services for Usergrid system.

There is a newer version: 0.0.27.1

/*******************************************************************************
 * 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;

import static org.usergrid.locking.LockPathBuilder.buildPath;
import static org.usergrid.utils.ConversionUtils.bytes;

import java.util.UUID;

import org.apache.commons.codec.binary.Hex;
import org.usergrid.locking.exception.UGLockException;
import org.usergrid.locking.noop.NoOpLockImpl;

/**
 * @author tnine
 *
 */
public class LockHelper {

  
  private static final NoOpLockImpl NO_OP_LOCK = new NoOpLockImpl();

  /**
   * Build a string path for this lock.  Since it's specifically for updating a property, the property
   * needs appended to the path.  If the property is null, it's getting deleted, so a lock on it isn't
   * neccessary.  In that case, a no op lock is returned
   * 
   * @param applicationId
   * @param path
   * @return
   * @throws UGLockException 
   */
  public static Lock getUniqueUpdateLock(LockManager manager, UUID applicationId, Object value , String... path) throws UGLockException {
    //we have no value, therefore there's nothing to lock
    if(value == null){
      return NO_OP_LOCK;
    }
    
    return manager.createLock(applicationId, buildPath(Hex.encodeHexString( bytes(value)), path));
    
  }

}