/*
    * 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.superstep_output;
  
  import org.apache.giraph.graph.Vertex;
  import org.apache.giraph.io.SimpleVertexWriter;
  import org.apache.hadoop.io.Writable;
  import org.apache.hadoop.io.WritableComparable;
  
  import java.io.IOException;
  
  /**
   * Class to use as {@link SuperstepOutput} when we don't have output during
   * computation. All the methods are no-ops.
   *
   * @param <I> Vertex id
   * @param <V> Vertex value
   * @param <E> Edge value
   */
  public class NoOpSuperstepOutput<I extends WritableComparable,
      V extends Writable, E extends Writable> implements
      SuperstepOutput<I, V, E> {
    @Override
    public SimpleVertexWriter<I, V, E> getVertexWriter() {
      return new SimpleVertexWriter<I, V, E>() {
        @Override
        public void writeVertex(Vertex<I, V, E> vertex) throws IOException,
            InterruptedException {
        }
      };
    }
  
    @Override
    public void returnVertexWriter(
        SimpleVertexWriter<I, V, E> vertexWriter) {
    }
  
    @Override
    public void postApplication() {
    }
  }