hadoop-tools/hadoop-rumen/src/main/java/org/apache/hadoop/tools/rumen/ParsedHost.java

/**
 * 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.hadoop.tools.rumen;

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;
import java.util.regex.Matcher;

import org.apache.hadoop.tools.rumen.datatypes.NodeName;

public class ParsedHost {
  private final String rackName;
  private final String nodeName;

  /**
   * TODO the following only works for /rack/host format. Change to support
   * arbitrary level of network names.
   */
  private static final Pattern splitPattern = Pattern
      .compile("/([^/]+)/([^/]+)");

  /**
   * TODO handle arbitrary level of network names.
   */
  static int numberOfDistances() {
    return 3;
  }

  String nameComponent(int i) throws IllegalArgumentException {
    switch (i) {
    case 0:
      return rackName;

    case 1:
      return nodeName;

    default:
      throw new IllegalArgumentException(
          "Host location component index out of range.");
    }
  }

  @Override
  public int hashCode() {
    return rackName.hashCode() * 17 + nodeName.hashCode();
  }

  public static ParsedHost parse(String name) {
    // separate out the node name
    Matcher matcher = splitPattern.matcher(name);

    if (!matcher.matches())
      return null;

    return new ParsedHost(matcher.group(1), matcher.group(2));
  }

  private String process(String name) {
    return name == null 
           ? null 
           : name.startsWith("/") ? name.substring(1) : name;
  }
  
  public ParsedHost(LoggedLocation loc) {
    List<NodeName> coordinates = loc.getLayers();

    rackName = coordinates.get(0).getRackName();
    nodeName = coordinates.get(1).getHostName();
  }

  LoggedLocation makeLoggedLocation() {
    LoggedLocation result = new LoggedLocation();

    List<String> coordinates = new ArrayList<String>();

    coordinates.add(rackName);
    coordinates.add(nodeName);

    result.setLayers(coordinates);

    return result;
  }
  
  public String getNodeName() {
    return nodeName;
  }
  
  public String getRackName() {
    return rackName;
  }

  // expects the broadest name first
  ParsedHost(String rackName, String nodeName) {
    this.rackName = process(rackName);
    this.nodeName = process(nodeName);
  }

  @Override
  public boolean equals(Object other) {
    if (!(other instanceof ParsedHost)) {
      return false;
    }
    ParsedHost host = (ParsedHost) other;
    return (nodeName.equals(host.nodeName) && rackName.equals(host.rackName));
  }

  int distance(ParsedHost other) {
    if (nodeName.equals(other.nodeName)) {
      return 0;
    }

    if (rackName.equals(other.rackName)) {
      return 1;
    }

    return 2;
  }
}