/*

  * 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.examples;

 import org.apache.giraph.graph.BasicComputation;

 import org.apache.giraph.graph.Vertex;

 import org.apache.giraph.worker.DefaultWorkerContext;

 import org.apache.hadoop.io.DoubleWritable;

 import org.apache.hadoop.io.FloatWritable;

 import org.apache.hadoop.io.LongWritable;

 import java.io.IOException;

 import java.util.concurrent.atomic.AtomicLong;

 /**

  * Vertex to test the local variables in Computation, and pre/postSuperstep

  * methods

  */

 public class TestComputationStateComputation extends BasicComputation<

     LongWritable, DoubleWritable, FloatWritable, DoubleWritable> {

   /** How many compute threads to use in the test */

   public static final int NUM_COMPUTE_THREADS = 10;

   /** How many vertices to create for the test */

   public static final int NUM_VERTICES = 100;

   /** How many partitions to have */

   public static final int NUM_PARTITIONS = 25;

   /**

    * The counter should hold the number of vertices in this partition,

    * plus the current superstep

    */

   private long counter;

   @Override

   public void compute(

       Vertex<LongWritable, DoubleWritable, FloatWritable> vertex,

       Iterable<DoubleWritable> messages) throws IOException {

     counter++;

     if (getSuperstep() > 5) {

       vertex.voteToHalt();

     }

   }

   @Override

   public void preSuperstep() {

     counter =

       ((TestComputationStateWorkerContext) getWorkerContext()).superstepCounter;

   }

   @Override

   public void postSuperstep() {

     ((TestComputationStateWorkerContext) getWorkerContext()).totalCounter

         .addAndGet(counter);

   }

   /**

    * WorkerContext for TestComputationState

    */

   public static class TestComputationStateWorkerContext extends

       DefaultWorkerContext {

     /** Current superstep */

     private long superstepCounter;

     /**

      * This counter should hold the sum of Computation's counters

      */

     private AtomicLong totalCounter;

     @Override

     public void preSuperstep() {

       superstepCounter = getSuperstep();

       totalCounter = new AtomicLong(0);

     }

     @Override

     public void postSuperstep() {

       assertEquals(totalCounter.get(),

           NUM_COMPUTE_THREADS * superstepCounter + getTotalNumVertices());

     }

   }

   /**

    * Throws exception if values are not equal.

    *

    * @param expected Expected value

    * @param actual   Actual value

    */

   private static void assertEquals(long expected, long actual) {

     if (expected != actual) {

       throw new RuntimeException("expected: " + expected +

           ", actual: " + actual);

     }

   }

 }