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, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hdfs.server.protocol;
019
020import org.apache.hadoop.hdfs.StorageType;
021
022import java.util.UUID;
023
024/**
025 * Class captures information of a storage in Datanode.
026 */
027public class DatanodeStorage {
028  /** The state of the storage. */
029  public enum State {
030    NORMAL,
031    
032    /**
033     * A storage that represents a read-only path to replicas stored on a shared storage device.
034     * Replicas on {@link #READ_ONLY_SHARED} storage are not counted towards live replicas.
035     * 
036     * <p>
037     * In certain implementations, a {@link #READ_ONLY_SHARED} storage may be correlated to 
038     * its {@link #NORMAL} counterpart using the {@link DatanodeStorage#storageID}.  This
039     * property should be used for debugging purposes only.
040     * </p> 
041     */
042    READ_ONLY_SHARED;
043  }
044  
045  private final String storageID;
046  private final State state;
047  private final StorageType storageType;
048
049  /**
050   * Create a storage with {@link State#NORMAL} and {@link StorageType#DEFAULT}.
051   *
052   * @param storageID
053   */
054  public DatanodeStorage(String storageID) {
055    this(storageID, State.NORMAL, StorageType.DEFAULT);
056  }
057
058  public DatanodeStorage(String sid, State s, StorageType sm) {
059    this.storageID = sid;
060    this.state = s;
061    this.storageType = sm;
062  }
063
064  public String getStorageID() {
065    return storageID;
066  }
067
068  public State getState() {
069    return state;
070  }
071
072  public StorageType getStorageType() {
073    return storageType;
074  }
075
076  /**
077   * Generate new storage ID. The format of this string can be changed
078   * in the future without requiring that old storage IDs be updated.
079   *
080   * @return unique storage ID
081   */
082  public static String generateUuid() {
083    return "DS-" + UUID.randomUUID();
084  }
085
086  @Override
087  public boolean equals(Object other){
088    if (other == this) {
089      return true;
090    }
091
092    if ((other == null) ||
093        !(other instanceof DatanodeStorage)) {
094      return false;
095    }
096    DatanodeStorage otherStorage = (DatanodeStorage) other;
097    return otherStorage.getStorageID().compareTo(getStorageID()) == 0;
098  }
099
100  @Override
101  public int hashCode() {
102    return getStorageID().hashCode();
103  }
104}