/*

  * 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;

 import org.apache.giraph.conf.DefaultImmutableClassesGiraphConfigurable;

 import org.apache.hadoop.conf.Configuration;

 import org.apache.hadoop.io.Text;

 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.util.ReflectionUtils;

 import java.io.DataInput;

 import java.io.DataOutput;

 import java.io.IOException;

 import java.util.List;

 /**

  * Common interface for {@link VertexInputFormat} and {@link EdgeInputFormat}.

  *

  * @param <I> Vertex id

  * @param <V> Vertex data

  * @param <E> Edge data

  */

 public abstract class GiraphInputFormat<I extends WritableComparable,

     V extends Writable, E extends Writable> extends

     DefaultImmutableClassesGiraphConfigurable<I, V, E> {

   /**

    * Check that input is valid.

    *

    * @param conf Configuration

    */

   public abstract void checkInputSpecs(Configuration conf);

   /**

    * Get the list of input splits for the format.

    *

    * @param context The job context

    * @param minSplitCountHint Minimum number of splits to create (hint)

    * @return The list of input splits

    * @throws IOException

    * @throws InterruptedException

    */

   public abstract List<InputSplit> getSplits(JobContext context,

       int minSplitCountHint) throws IOException, InterruptedException;

   /**

    * Write input split info to DataOutput.

    *

    * @param inputSplit InputSplit

    * @param dataOutput DataOutput

    */

   public void writeInputSplit(InputSplit inputSplit,

       DataOutput dataOutput) throws IOException {

     Text.writeString(dataOutput, inputSplit.getClass().getName());

     ((Writable) inputSplit).write(dataOutput);

   }

   /**

    * Read input split info from DataInput.

    *

    * @param dataInput DataInput

    * @return InputSplit

    */

   public InputSplit readInputSplit(DataInput dataInput) throws IOException,

       ClassNotFoundException {

     String inputSplitClass = Text.readString(dataInput);

     InputSplit inputSplit = (InputSplit) ReflectionUtils.newInstance(

             getConf().getClassByName(inputSplitClass), getConf());

     ((Writable) inputSplit).readFields(dataInput);

     return inputSplit;

   }

 }