/*
    * 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.utils;
  
  import org.apache.giraph.aggregators.TextAppendAggregator;
  import org.apache.giraph.master.MasterAggregatorUsage;
  import org.apache.giraph.worker.WorkerAggregatorUsage;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.io.Text;
  import org.apache.log4j.Logger;
  
  /**
   * Helper class for using aggregator which gathers log messages from workers
   * and prints them on master.
   *
   * If you want to track what's going on in your application,
   * and want to have all those logs accessible in a single place in the end of
   * each superstep, you can use option from this class.
   *
   * If you use a lot of log messages this might slow down your application,
   * but it can easily be turned on/off without changing your code just by
   * switching the option.
   */
  public class MasterLoggingAggregator {
    /** Whether or not to use master logging aggregator */
    public static final String USE_MASTER_LOGGING_AGGREGATOR =
        "giraph.useMasterLoggingAggregator";
    /** Default is not using master logging aggregator */
    public static final boolean USE_MASTER_LOGGING_AGGREGATOR_DEFAULT = false;
    /** Name of aggregator which will be gathering the logs */
    public static final String MASTER_LOGGING_AGGREGATOR_NAME =
        "masterLoggingAggregator";
  
    /** Class logger */
    private static final Logger LOG =
        Logger.getLogger(MasterLoggingAggregator.class);
  
    /** Do not instantiate */
    private MasterLoggingAggregator() {
    }
  
    /**
     * Check if master logging aggregator is used.
     *
     * @param conf Configuration
     * @return True iff master logging aggregator is used
     */
    public static boolean useMasterLoggingAggregator(Configuration conf) {
      return conf.getBoolean(USE_MASTER_LOGGING_AGGREGATOR,
          USE_MASTER_LOGGING_AGGREGATOR_DEFAULT);
    }
  
    /**
     * Set whether or not master logging aggregator should be used
     *
     * @param useMasterLoggingAggregator Whether or not we want
     *                                   master logging aggregator to be used
     * @param conf                       Configuration
     */
    public static void setUseMasterLoggingAggregator(
        boolean useMasterLoggingAggregator, Configuration conf) {
      conf.setBoolean(USE_MASTER_LOGGING_AGGREGATOR, useMasterLoggingAggregator);
    }
  
    /**
     * Aggregate some message to master logging aggregator,
     * if the option for using it is set in the configuration.
     *
     * This is the method application implementation should use
     * in order to add message to the aggregator.
     *
     * @param message               Message to log
     * @param workerAggregatorUsage Worker aggregator usage
     *                              (can be Vertex, WorkerContext, etc)
     * @param conf                  Configuration
     */
    public static void aggregate(String message,
        WorkerAggregatorUsage workerAggregatorUsage, Configuration conf) {
      if (useMasterLoggingAggregator(conf)) {
        workerAggregatorUsage.aggregate(
            MASTER_LOGGING_AGGREGATOR_NAME, new Text(message));
      }
    }
 
   /**
    * Register master logging aggregator,
    * if the option for using it is set in the configuration.
    *
    * This method will be called by Giraph infrastructure on master.
    *
    * @param masterAggregatorUsage Master aggregator usage
    * @param conf                  Configuration
    */
   public static void registerAggregator(
       MasterAggregatorUsage masterAggregatorUsage, Configuration conf) {
     if (useMasterLoggingAggregator(conf)) {
       try {
         masterAggregatorUsage.registerAggregator(MASTER_LOGGING_AGGREGATOR_NAME,
             TextAppendAggregator.class);
       } catch (InstantiationException e) {
         throw new IllegalStateException("registerAggregator: " +
             "InstantiationException occurred");
       } catch (IllegalAccessException e) {
         throw new IllegalStateException("registerAggregator: " +
             "IllegalAccessException occurred");
       }
     }
   }
 
   /**
    * Print value of master logging aggregator on the master log,
    * if the option for using it is set in the configuration.
    *
    * This method will be called by Giraph infrastructure on master.
    *
    * @param masterAggregatorUsage Master aggregator usage
    * @param conf                  Configuration
    */
   public static void logAggregatedValue(
       MasterAggregatorUsage masterAggregatorUsage, Configuration conf) {
     if (useMasterLoggingAggregator(conf) && LOG.isInfoEnabled()) {
       LOG.info("logAggregatedValue: \n" +
           masterAggregatorUsage.getAggregatedValue(
               MASTER_LOGGING_AGGREGATOR_NAME));
     }
   }
 }