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.protocol;
019
020import org.apache.hadoop.classification.InterfaceAudience;
021import org.apache.hadoop.classification.InterfaceStability;
022import org.apache.hadoop.io.erasurecode.ECSchema;
023
024/**
025 * A policy about how to write/read/code an erasure coding file.
026 */
027@InterfaceAudience.Public
028@InterfaceStability.Evolving
029public final class ErasureCodingPolicy {
030
031  private final String name;
032  private final ECSchema schema;
033  private final int cellSize;
034  private final byte id;
035
036  public ErasureCodingPolicy(String name, ECSchema schema,
037      int cellSize, byte id) {
038    this.name = name;
039    this.schema = schema;
040    this.cellSize = cellSize;
041    this.id = id;
042  }
043
044  public ErasureCodingPolicy(ECSchema schema, int cellSize, byte id) {
045    this(composePolicyName(schema, cellSize), schema, cellSize, id);
046  }
047
048  private static String composePolicyName(ECSchema schema, int cellSize) {
049    assert cellSize % 1024 == 0;
050    return schema.getCodecName().toUpperCase() + "-" +
051        schema.getNumDataUnits() + "-" + schema.getNumParityUnits() +
052        "-" + cellSize / 1024 + "k";
053  }
054
055  public String getName() {
056    return name;
057  }
058
059  public ECSchema getSchema() {
060    return schema;
061  }
062
063  public int getCellSize() {
064    return cellSize;
065  }
066
067  public int getNumDataUnits() {
068    return schema.getNumDataUnits();
069  }
070
071  public int getNumParityUnits() {
072    return schema.getNumParityUnits();
073  }
074
075  public String getCodecName() {
076    return schema.getCodecName();
077  }
078
079  public byte getId() {
080    return id;
081  }
082
083  @Override
084  public boolean equals(Object o) {
085    if (this == o) {
086      return true;
087    }
088    if (o == null || getClass() != o.getClass()) {
089      return false;
090    }
091    ErasureCodingPolicy that = (ErasureCodingPolicy) o;
092
093    return that.getName().equals(name) &&
094        that.getCellSize() == cellSize &&
095        that.getSchema().equals(schema);
096  }
097
098  @Override
099  public int hashCode() {
100    int result = name.hashCode();
101    result = 31 * result + schema.hashCode();
102    result = 31 * result + cellSize;
103    return result;
104  }
105
106  @Override
107  public String toString() {
108    return "ErasureCodingPolicy=[" + "Name=" + name + ", "
109        + "Schema=[" + schema.toString() + "], "
110        + "CellSize=" + cellSize + " " + "]";
111  }
112}