/*
    * 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.giraph.job;
  
  import org.apache.giraph.conf.GiraphConfiguration;
  import org.apache.giraph.conf.GiraphConstants;
  import org.apache.giraph.utils.CounterUtils;
  import org.apache.hadoop.mapreduce.Job;
  import org.apache.log4j.Logger;
  
  /**
   * Utility methods for halting application while running
   */
  public class HaltApplicationUtils {
    /** Do not instantiate */
    private HaltApplicationUtils() { }
  
    /**
     * Wait for halt info to become available and print instructions on how to
     * halt
     *
     * @param submittedJob Submitted job
     * @param conf         Configuration
     */
    public static void printHaltInfo(Job submittedJob,
        GiraphConfiguration conf) {
      String zkServer = CounterUtils.waitAndGetCounterNameFromGroup(
          submittedJob, GiraphConstants.ZOOKEEPER_SERVER_PORT_COUNTER_GROUP);
      String haltNode = CounterUtils.waitAndGetCounterNameFromGroup(
          submittedJob, GiraphConstants.ZOOKEEPER_HALT_NODE_COUNTER_GROUP);
      if (zkServer != null && haltNode != null) {
        GiraphConstants.HALT_INSTRUCTIONS_WRITER_CLASS.newInstance(
            conf).writeHaltInstructions(zkServer, haltNode);
      }
    }
  
    /**
     * Writer of instructions about how to halt
     */
    public interface HaltInstructionsWriter {
      /**
       * Write instructions about how to halt
       *
       * @param zkServer ZooKeeper server
       * @param haltNode ZooKeeper node which should be created in order to halt
       */
      void writeHaltInstructions(String zkServer, String haltNode);
    }
  
    /**
     * Default implementation of {@link HaltInstructionsWriter} - points to how
     * to use {@link org.apache.giraph.zk.ZooKeeperNodeCreator} to halt
     */
    public static class DefaultHaltInstructionsWriter implements
        HaltInstructionsWriter {
      /** Class logger */
      private static final Logger LOG = Logger.getLogger(
          DefaultHaltInstructionsWriter.class);
  
      @Override
      public void writeHaltInstructions(String zkServer, String haltNode) {
        if (LOG.isInfoEnabled()) {
          LOG.info("writeHaltInstructions: " +
              "To halt after next superstep execute: " +
              "'bin/halt-application --zkServer " + zkServer +
              " --zkNode " + haltNode + "'");
        }
      }
    }
  }