/*

  * 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.comm.requests;

 import org.apache.giraph.comm.ServerData;

 import org.apache.giraph.graph.VertexMutations;

 import org.apache.giraph.metrics.GiraphMetrics;

 import org.apache.giraph.metrics.MetricNames;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import org.apache.log4j.Logger;

 import com.google.common.collect.Maps;

 import com.yammer.metrics.core.Histogram;

 import java.io.DataInput;

 import java.io.DataOutput;

 import java.io.IOException;

 import java.util.Map;

 import java.util.Map.Entry;

 import java.util.concurrent.ConcurrentHashMap;

 import java.util.concurrent.ConcurrentMap;

 /**

  * Send a collection of vertex mutations for a partition. This type of request

  * is used for two purposes: 1) sending mutation requests generated due to user

  * compute function in the middle of the execution of a superstep, and

  * 2) sending mutation requests due to partition migration.

  *

  * @param <I> Vertex id

  * @param <V> Vertex data

  * @param <E> Edge data

  */

 @SuppressWarnings("rawtypes")

 public class SendPartitionMutationsRequest<I extends WritableComparable,

     V extends Writable, E extends Writable> extends

     WritableRequest<I, V, E> implements WorkerRequest<I, V, E> {

   /** Class logger */

   private static final Logger LOG =

       Logger.getLogger(SendPartitionMutationsRequest.class);

   /** Partition id */

   private int partitionId;

   /** Mutations sent for a partition */

   private Map<I, VertexMutations<I, V, E>> vertexIdMutations;

   /**

    * Constructor used for reflection only

    */

   public SendPartitionMutationsRequest() { }

   /**

    * Constructor used to send request.

    *

    * @param partitionId Partition to send the request to

    * @param vertexIdMutations Map of mutations to send

    */

   public SendPartitionMutationsRequest(

       int partitionId,

       Map<I, VertexMutations<I, V, E>> vertexIdMutations) {

     this.partitionId = partitionId;

     this.vertexIdMutations = vertexIdMutations;

   }

   @Override

   public void readFieldsRequest(DataInput input) throws IOException {

     partitionId = input.readInt();

     int vertexIdMutationsSize = input.readInt();

     // The request is going to be served by adding/merging it with the current

     // mutations stored in ServerData. Since the mutations stored in ServerData

     // is in the form of a ConcurrentMap, the data here is being read in this

     // form, so it would be more efficient to merge/add the mutations in this

     // request with/to mutations stored in SeverData.

     vertexIdMutations = Maps.newConcurrentMap();

     for (int i = 0; i < vertexIdMutationsSize; ++i) {

       I vertexId = getConf().createVertexId();

       vertexId.readFields(input);

       VertexMutations<I, V, E> vertexMutations =

           new VertexMutations<I, V, E>();

       vertexMutations.setConf(getConf());

       vertexMutations.readFields(input);

       if (vertexIdMutations.put(vertexId, vertexMutations) != null) {

         throw new IllegalStateException(

             "readFields: Already has vertex id " + vertexId);

       }

     }

   }

   @Override

   public void writeRequest(DataOutput output) throws IOException {

     output.writeInt(partitionId);

     output.writeInt(vertexIdMutations.size());

     for (Entry<I, VertexMutations<I, V, E>> entry :

         vertexIdMutations.entrySet()) {

       entry.getKey().write(output);

       entry.getValue().write(output);

     }

   }

   @Override

   public RequestType getType() {

     return RequestType.SEND_PARTITION_MUTATIONS_REQUEST;

   }

   @Override

   public void doRequest(ServerData<I, V, E> serverData) {

     ConcurrentMap<Integer, ConcurrentMap<I, VertexMutations<I, V, E>>>

         partitionMutations = serverData.getPartitionMutations();

     Histogram verticesInMutationHist = GiraphMetrics.get().perSuperstep()

         .getUniformHistogram(MetricNames.VERTICES_IN_MUTATION_REQUEST);

     int mutationSize = 0;

     for (Map<I, VertexMutations<I, V, E>> map : partitionMutations.values()) {

       mutationSize += map.size();

     }

     verticesInMutationHist.update(mutationSize);

     // If the request is a result of sending mutations in the middle of the

     // superstep to local partitions, the request is "short-circuit"ed and

     // vertexIdMutations is coming from an instance of SendMutationsCache.

     // Since the vertex mutations are created locally, they are not stored in

     // a ConcurrentMap. So, we first need to transform the data structure

     // for more efficiently merge/add process.

     if (!(vertexIdMutations instanceof ConcurrentMap)) {

       vertexIdMutations = new ConcurrentHashMap<>(vertexIdMutations);

     }

     ConcurrentMap<I, VertexMutations<I, V, E>> currentVertexIdMutations =

         partitionMutations.putIfAbsent(partitionId,

             (ConcurrentMap<I, VertexMutations<I, V, E>>) vertexIdMutations);

     if (currentVertexIdMutations != null) {

       for (Entry<I, VertexMutations<I, V, E>> entry : vertexIdMutations

           .entrySet()) {

         VertexMutations<I, V, E> mutations = currentVertexIdMutations

             .putIfAbsent(entry.getKey(), entry.getValue());

         if (mutations != null) {

           synchronized (mutations) {

             mutations.addVertexMutations(entry.getValue());

           }

         }

       }

     }

   }

   @Override

   public int getSerializedSize() {

     return WritableRequest.UNKNOWN_SIZE;

   }

 }