Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.reef.io.network.group.impl.driver;
020
021import org.apache.reef.io.network.group.api.driver.TaskNode;
022import org.apache.reef.io.network.util.Pair;
023import org.apache.reef.wake.Identifier;
024import org.apache.reef.wake.IdentifierFactory;
025
026import java.io.*;
027import java.util.LinkedList;
028import java.util.List;
029
030/**
031 * Utility class for encoding a Topology into a byte array and vice versa.
032 */
033public final class TopologySerializer {
034
035  /**
036   * Shouldn't be instantiated.
037   */
038  private TopologySerializer() {
039  }
040
041  /**
042   * Recursively encode TaskNodes of a Topology into a byte array.
043   *
044   * @param root the root node of the subtree to encode
045   * @return encoded byte array
046   */
047  public static byte[] encode(final TaskNode root) {
048    try (final ByteArrayOutputStream bstream = new ByteArrayOutputStream();
049         final DataOutputStream dstream = new DataOutputStream(bstream)) {
050      encodeHelper(dstream, root);
051      return bstream.toByteArray();
052
053    } catch (final IOException e) {
054      throw new RuntimeException("Exception while encoding topology of " + root.getTaskId(), e);
055    }
056  }
057
058  private static void encodeHelper(final DataOutputStream dstream,
059                                   final TaskNode node) throws IOException {
060    dstream.writeUTF(node.getTaskId());
061    dstream.writeInt(node.getNumberOfChildren());
062    for (final TaskNode child : node.getChildren()) {
063      encodeHelper(dstream, child);
064    }
065  }
066
067  /**
068   * Recursively translate a byte array into a TopologySimpleNode and a list of task Identifiers.
069   *
070   * @param data encoded byte array
071   * @param ifac IdentifierFactory needed to generate Identifiers from String Ids
072   * @return decoded TopologySimpleNode and a lexicographically sorted list of task Identifiers
073   */
074  public static Pair<TopologySimpleNode, List<Identifier>> decode(
075      final byte[] data,
076      final IdentifierFactory ifac) {
077
078    try (final DataInputStream dstream = new DataInputStream(new ByteArrayInputStream(data))) {
079      final List<Identifier> activeSlaveTasks = new LinkedList<>();
080      final TopologySimpleNode retNode = decodeHelper(dstream, activeSlaveTasks, ifac);
081      return new Pair<>(retNode, activeSlaveTasks);
082
083    } catch (final IOException e) {
084      throw new RuntimeException("Exception while decoding message", e);
085    }
086  }
087
088  private static TopologySimpleNode decodeHelper(
089      final DataInputStream dstream,
090      final List<Identifier> activeSlaveTasks,
091      final IdentifierFactory ifac) throws IOException {
092    final String taskId = dstream.readUTF();
093    activeSlaveTasks.add(ifac.getNewInstance(taskId));
094    final TopologySimpleNode retNode = new TopologySimpleNode(taskId);
095
096    final int children = dstream.readInt();
097    for (int index = 0; index < children; index++) {
098      final TopologySimpleNode child = decodeHelper(dstream, activeSlaveTasks, ifac);
099      retNode.addChild(child);
100    }
101
102    return retNode;
103  }
104}