/*

  * 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.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import org.apache.hadoop.mapreduce.InputSplit;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 import java.io.IOException;

 /**

  * Input format for reading single edges.  Provides access to

  * ImmutableClassesGiraphConfiguration.

  *

  * It's guaranteed that whatever parameters are set in the configuration are

  * also going to be available in all method arguments related to this input

  * format (context in getSplits and createEdgeReader; methods invoked on

  * EdgeReader). So if backing input format relies on some parameters from

  * configuration, you can safely set them for example in

  * {@link #setConf(org.apache.giraph.conf.ImmutableClassesGiraphConfiguration)}.

  *

  * @param <I> Vertex id

  * @param <E> Edge data

  */

 public abstract class EdgeInputFormat<I extends WritableComparable,

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

   /**

    * Create an edge reader for a given split. The framework will call

    * {@link EdgeReader#initialize(InputSplit, TaskAttemptContext)} before

    * the split is used.

    *

    * @param split the split to be read

    * @param context the information about the task

    * @return a new record reader

    * @throws IOException

    */

   public abstract EdgeReader<I, E> createEdgeReader(

       InputSplit split,

       TaskAttemptContext context) throws IOException;

 }