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.util;
019
020import java.util.Arrays;
021
022import com.google.common.base.Preconditions;
023
024/**
025 * Similar to {@link EnumCounters} except that the value type is double.
026 *
027 * @param <E> the enum type
028 */
029public class EnumDoubles<E extends Enum<E>> {
030  /** The class of the enum. */
031  private final Class<E> enumClass;
032  /** An array of doubles corresponding to the enum type. */
033  private final double[] doubles;
034
035  /**
036   * Construct doubles for the given enum constants.
037   * @param enumClass the enum class.
038   */
039  public EnumDoubles(final Class<E> enumClass) {
040    final E[] enumConstants = enumClass.getEnumConstants();
041    Preconditions.checkNotNull(enumConstants);
042    this.enumClass = enumClass;
043    this.doubles = new double[enumConstants.length];
044  }
045  
046  /** @return the value corresponding to e. */
047  public final double get(final E e) {
048    return doubles[e.ordinal()];
049  }
050
051  /** Negate all values. */
052  public final void negation() {
053    for(int i = 0; i < doubles.length; i++) {
054      doubles[i] = -doubles[i];
055    }
056  }
057  
058  /** Set e to the given value. */
059  public final void set(final E e, final double value) {
060    doubles[e.ordinal()] = value;
061  }
062
063  /** Set the values of this object to that object. */
064  public final void set(final EnumDoubles<E> that) {
065    for(int i = 0; i < doubles.length; i++) {
066      this.doubles[i] = that.doubles[i];
067    }
068  }
069
070  /** Reset all values to zero. */
071  public final void reset() {
072    for(int i = 0; i < doubles.length; i++) {
073      this.doubles[i] = 0.0;
074    }
075  }
076
077  /** Add the given value to e. */
078  public final void add(final E e, final double value) {
079    doubles[e.ordinal()] += value;
080  }
081
082  /** Add the values of that object to this. */
083  public final void add(final EnumDoubles<E> that) {
084    for(int i = 0; i < doubles.length; i++) {
085      this.doubles[i] += that.doubles[i];
086    }
087  }
088
089  /** Subtract the given value from e. */
090  public final void subtract(final E e, final double value) {
091    doubles[e.ordinal()] -= value;
092  }
093
094  /** Subtract the values of this object from that object. */
095  public final void subtract(final EnumDoubles<E> that) {
096    for(int i = 0; i < doubles.length; i++) {
097      this.doubles[i] -= that.doubles[i];
098    }
099  }
100
101  @Override
102  public boolean equals(Object obj) {
103    if (obj == this) {
104      return true;
105    } else if (obj == null || !(obj instanceof EnumDoubles)) {
106      return false;
107    }
108    final EnumDoubles<?> that = (EnumDoubles<?>)obj;
109    return this.enumClass == that.enumClass
110        && Arrays.equals(this.doubles, that.doubles);
111  }
112
113  @Override
114  public int hashCode() {
115    return Arrays.hashCode(doubles);
116  }
117
118  @Override
119  public String toString() {
120    final E[] enumConstants = enumClass.getEnumConstants();
121    final StringBuilder b = new StringBuilder();
122    for(int i = 0; i < doubles.length; i++) {
123      final String name = enumConstants[i].name();
124      b.append(name).append("=").append(doubles[i]).append(", ");
125    }
126    return b.substring(0, b.length() - 2);
127  }
128}