/*

  * 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.EdgeInputFormat;

 import org.apache.giraph.io.EdgeReader;

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

 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;

 /**

  * Edge input format which wraps several edge input formats.

  * Provides the way to read data from multiple sources,

  * using several different input formats.

  *

  * @param <I> Vertex id

  * @param <E> Edge data

  */

 public class MultiEdgeInputFormat<I extends WritableComparable,

     E extends Writable> extends EdgeInputFormat<I, E> {

   /** Edge input formats */

   private List<EdgeInputFormat<I, E>> edgeInputFormats;

   @Override public void checkInputSpecs(Configuration conf) {

     for (EdgeInputFormat edgeInputFormat : edgeInputFormats) {

       edgeInputFormat.checkInputSpecs(conf);

     }

   }

   @Override

   public void setConf(

       ImmutableClassesGiraphConfiguration<I, Writable, E> conf) {

     super.setConf(conf);

     edgeInputFormats =

         EdgeInputFormatDescription.createEdgeInputFormats(getConf());

     if (edgeInputFormats.isEmpty()) {

       throw new IllegalStateException("setConf: Using MultiEdgeInputFormat " +

           "without specifying edge inputs");

     }

   }

   @Override

   public EdgeReader<I, E> createEdgeReader(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;

         EdgeInputFormat<I, E> edgeInputFormat =

             edgeInputFormats.get(split.getInputFormatIndex());

         EdgeReader<I, E> edgeReader =

             edgeInputFormat.createEdgeReader(split.getSplit(), context);

         return new WrappedEdgeReader<I, E>(

             edgeReader, edgeInputFormat.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("createEdgeReader: Got InputSplit which" +

           " was not created by this class: " + inputSplit.getClass().getName());

     }

   }

   @Override

   public List<InputSplit> getSplits(JobContext context,

       int minSplitCountHint) 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) {

       return MultiInputUtils.getSplits(

           context, minSplitCountHint, edgeInputFormats);

     }

   }

   @Override

   public void writeInputSplit(InputSplit inputSplit,

       DataOutput dataOutput) throws IOException {

     MultiInputUtils.writeInputSplit(inputSplit, dataOutput, edgeInputFormats);

   }

   @Override

   public InputSplit readInputSplit(

       DataInput dataInput) throws IOException, ClassNotFoundException {

     return MultiInputUtils.readInputSplit(dataInput, edgeInputFormats);

   }

 }