/*

  * 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));

     }

   }

 }