/*
 * 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 java.io.IOException;

import org.apache.giraph.conf.DefaultImmutableClassesGiraphConfigurable;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.OutputCommitter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

/**
 * abstract class which can only write edges
 *
 * @param <I> Vertex id
 * @param <V> Vertex value
 * @param <E> Edge value
 */
@SuppressWarnings("rawtypes")
public abstract class EdgeOutputFormat<
    I extends WritableComparable, V extends Writable,
    E extends Writable> extends
    DefaultImmutableClassesGiraphConfigurable<I, V, E> {
  /**
   * Create an edge writer for a given split. The framework will call
   * {@link EdgeWriter#initialize(TaskAttemptContext)} before
   * the split is used.
   *
   * @param context the information about the task
   * @return a new vertex writer
   * @throws IOException
   * @throws InterruptedException
   */
  public abstract EdgeWriter<I, V, E> createEdgeWriter(
    TaskAttemptContext context) throws IOException, InterruptedException;

  /**
   * Check for validity of the output-specification for the job.
   * (Copied from Hadoop OutputFormat)
   *
   * <p>This is to validate the output specification for the job when it is
   * a job is submitted.  Typically checks that it does not already exist,
   * throwing an exception when it already exists, so that output is not
   * overwritten.</p>
   *
   * @param  context information about the job
   * @throws IOException when output should not be attempted
   */
  public abstract void checkOutputSpecs(JobContext context)
    throws IOException, InterruptedException;

  /**
   * Get the output committer for this output format. This is responsible
   * for ensuring the output is committed correctly.
   * (Copied from Hadoop OutputFormat)
   *
   * @param context the task context
   * @return an output committer
   * @throws IOException
   * @throws InterruptedException
   */
  public abstract OutputCommitter getOutputCommitter(
    TaskAttemptContext context) throws IOException, InterruptedException;
}
