/*

  * 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.examples.SimpleSuperstepComputation.SimpleSuperstepVertexInputFormat;

 import org.apache.giraph.graph.Vertex;

 import org.apache.giraph.job.GiraphJob;

 import org.apache.giraph.worker.WorkerContext;

 import org.apache.hadoop.conf.Configuration;

 import org.apache.hadoop.fs.FileSystem;

 import org.apache.hadoop.fs.Path;

 import org.apache.hadoop.io.DoubleWritable;

 import org.apache.hadoop.io.FloatWritable;

 import org.apache.hadoop.io.IntWritable;

 import org.apache.hadoop.io.LongWritable;

 import org.apache.hadoop.mapreduce.Mapper.Context;

 import org.apache.hadoop.util.Tool;

 import org.apache.hadoop.util.ToolRunner;

 import java.io.DataOutputStream;

 import java.io.IOException;

 /**

  * Fully runnable example of how to

  * emit worker data to HDFS during a graph

  * computation.

  */

 public class SimpleVertexWithWorkerContext implements Tool {

   /** Directory name of where to write. */

   public static final String OUTPUTDIR = "svwwc.outputdir";

   /** Halting condition for the number of supersteps */

   private static final int TESTLENGTH = 30;

   /** Configuration */

   private Configuration conf;

   @Override

   public void setConf(Configuration conf) {

     this.conf = conf;

   }

   @Override

   public Configuration getConf() {

     return conf;

   }

   /**

    * Actual vetex implementation

    */

   public static class SimpleComputation extends BasicComputation<LongWritable,

       IntWritable, FloatWritable, DoubleWritable> {

     @Override

     public void compute(

         Vertex<LongWritable, IntWritable, FloatWritable> vertex,

         Iterable<DoubleWritable> messages) throws IOException {

       long superstep = getSuperstep();

       if (superstep < TESTLENGTH) {

         EmitterWorkerContext emitter = getWorkerContext();

         emitter.emit("vertexId=" + vertex.getId() +

             " superstep=" + superstep + "\n");

       } else {

         vertex.voteToHalt();

       }

     }

   }

   /**

    * Example worker context to emit data as part of a superstep.

    */

   @SuppressWarnings("rawtypes")

   public static class EmitterWorkerContext extends WorkerContext {

     /** File name prefix */

     private static final String FILENAME = "emitter_";

     /** Output stream to dump the strings. */

     private DataOutputStream out;

     @Override

     public void preApplication() {

       Context context = getContext();

       FileSystem fs;

       try {

         fs = FileSystem.get(context.getConfiguration());

         String p = context.getConfiguration()

             .get(SimpleVertexWithWorkerContext.OUTPUTDIR);

         if (p == null) {

           throw new IllegalArgumentException(

               SimpleVertexWithWorkerContext.OUTPUTDIR +

               " undefined!");

         }

         Path path = new Path(p);

         if (!fs.exists(path)) {

           throw new IllegalArgumentException(path +

               " doesn't exist");

         }

         Path outF = new Path(path, FILENAME +

             context.getTaskAttemptID());

         if (fs.exists(outF)) {

           throw new IllegalArgumentException(outF +

               " aready exists");

         }

         out = fs.create(outF);

       } catch (IOException e) {

         throw new RuntimeException(

             "can't initialize WorkerContext", e);

       }

     }

     @Override

     public void postApplication() {

       if (out != null) {

         try {

           out.flush();

           out.close();

         } catch (IOException e) {

           throw new RuntimeException(

               "can't finalize WorkerContext", e);

         }

         out = null;

       }

     }

     @Override

     public void preSuperstep() { }

     @Override

     public void postSuperstep() { }

     /**

      * Write this string to the output stream.

      *

      * @param s String to dump.

      */

     public void emit(String s) {

       try {

         out.writeUTF(s);

       } catch (IOException e) {

         throw new RuntimeException("can't emit", e);

       }

     }

   }

   @Override

   public int run(String[] args) throws Exception {

     if (args.length != 2) {

       throw new IllegalArgumentException(

           "run: Must have 2 arguments <output path> <# of workers>");

     }

     GiraphJob job = new GiraphJob(getConf(), getClass().getName());

     job.getConfiguration().setComputationClass(SimpleComputation.class);

     job.getConfiguration().setVertexInputFormatClass(

         SimpleSuperstepVertexInputFormat.class);

     job.getConfiguration().setWorkerContextClass(EmitterWorkerContext.class);

     job.getConfiguration().set(

         SimpleVertexWithWorkerContext.OUTPUTDIR, args[0]);

     job.getConfiguration().setWorkerConfiguration(Integer.parseInt(args[1]),

         Integer.parseInt(args[1]),

         100.0f);

     if (job.run(true)) {

       return 0;

     } else {

       return -1;

     }

   }

   /**

    * Executable from the command line.

    *

    * @param args Command line arguments.

    * @throws Exception

    */

   public static void main(String[] args) throws Exception {

     System.exit(ToolRunner.run(new SimpleVertexWithWorkerContext(), args));

   }

 }