/*
 * 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.ql.plan;

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

import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.ql.exec.Task;

/**
 * Conditional task resolution interface. This is invoked at run time to get the
 * task to invoke. Developers can plug in their own resolvers.
 */
public interface ConditionalResolver {
  /**
   * All conditional resolvers implement this interface.
   *
   * @param conf
   *          configuration
   * @param ctx
   *          opaque context
   * @return position of the task
   */
  List<Task<? extends Serializable>> getTasks(HiveConf conf, Object ctx);

}
