standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/LockTypeComparator.java

/*
 * 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.hadoop.hive.metastore;

import org.apache.hadoop.hive.metastore.api.LockType;

import java.io.Serializable;
import java.util.Comparator;
import java.util.Arrays;
import java.util.List;


/**
 * Sort more restrictive locks after less restrictive ones.
 */
public class LockTypeComparator implements Comparator<LockType>, Serializable {

  // the higher the integer value, the more restrictive the lock type is
  private List<LockType> orderOfRestrictiveness = Arrays.asList(
      LockType.SHARED_READ, LockType.SHARED_WRITE, LockType.EXCL_WRITE, LockType.EXCLUSIVE);

  @Override
  public int compare(LockType t1, LockType t2) {
    return orderOfRestrictiveness.indexOf(t1) - orderOfRestrictiveness.indexOf(t2);
  }
}