/*

  * 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.io.formats.multi;

 import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;

 import org.apache.giraph.io.MappingInputFormat;

 import org.apache.giraph.io.MappingReader;

 import org.apache.giraph.io.internal.WrappedMappingReader;

 import org.apache.hadoop.conf.Configuration;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import org.apache.hadoop.mapreduce.InputSplit;

 import org.apache.hadoop.mapreduce.JobContext;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 import java.io.DataInput;

 import java.io.DataOutput;

 import java.io.IOException;

 import java.util.List;

 /**

  * Mapping input format which wraps several mapping input formats.

  * Provides the way to read data from multiple sources,

  * using several different input formats.

  *

  * @param <I> Vertex id

  * @param <V> Vertex value

  * @param <E> Edge data

  * @param <B> Mapping target

  */

 public class MultiMappingInputFormat<I extends WritableComparable,

   V extends Writable, E extends Writable, B extends Writable>

   extends MappingInputFormat<I, V, E, B> {

   /** Mapping input formats */

   private List<MappingInputFormat<I, V, E, B>> mappingInputFormats;

   /**

    * Default constructor.

    */

   public MultiMappingInputFormat() {

   }

   @Override

   public void setConf(

     ImmutableClassesGiraphConfiguration<I, V, E> conf) {

     super.setConf(conf);

     mappingInputFormats =

       MappingInputFormatDescription.createMappingInputFormats(getConf());

     if (mappingInputFormats.isEmpty()) {

       throw new IllegalStateException("setConf: Using MultiVertexInputFormat " +

                                         "without specifying vertex inputs");

     }

   }

   @Override

   public MappingReader createMappingReader(

     InputSplit inputSplit, TaskAttemptContext context

   ) throws IOException {

     if (inputSplit instanceof InputSplitWithInputFormatIndex) {

       // When multithreaded input is used we need to make sure other threads

       // don't change context's configuration while we use it

       synchronized (context) {

         InputSplitWithInputFormatIndex split =

           (InputSplitWithInputFormatIndex) inputSplit;

         MappingInputFormat<I, V, E, B> mappingInputFormat =

           mappingInputFormats.get(split.getInputFormatIndex());

         MappingReader<I, V, E, B> mappingReader =

           mappingInputFormat.createMappingReader(split.getSplit(), context);

         return new WrappedMappingReader<I, V, E, B>(

           mappingReader, mappingInputFormat.getConf()) {

           @Override

           public void initialize(InputSplit inputSplit,

                                  TaskAttemptContext context) throws IOException,

             InterruptedException {

             // When multithreaded input is used we need to make sure other

             // threads don't change context's configuration while we use it

             synchronized (context) {

               super.initialize(inputSplit, context);

             }

           }

         };

       }

     } else {

       throw new IllegalStateException("createVertexReader: Got InputSplit " +

         "which was not created by this class: " +

         inputSplit.getClass().getName());

     }

   }

   @Override

   public void checkInputSpecs(Configuration conf) {

     for (MappingInputFormat mappingInputFormat : mappingInputFormats) {

       mappingInputFormat.checkInputSpecs(conf);

     }

   }

   @Override

   public List<InputSplit> getSplits(

     JobContext context, int minSplitCountHint

   ) throws IOException, InterruptedException {

     synchronized (context) {

       return MultiInputUtils.getSplits(

         context, minSplitCountHint, mappingInputFormats);

     }

   }

   @Override

   public void writeInputSplit(InputSplit inputSplit, DataOutput dataOutput)

     throws IOException {

     MultiInputUtils.writeInputSplit(

       inputSplit, dataOutput, mappingInputFormats);

   }

   @Override

   public InputSplit readInputSplit(

     DataInput dataInput) throws IOException, ClassNotFoundException {

     return MultiInputUtils.readInputSplit(dataInput, mappingInputFormats);

   }

 }