| /** |
| * 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.hdfs.util; |
| |
| import java.util.HashMap; |
| |
| import com.google.common.base.Preconditions; |
| |
| /** |
| * Counters for an enum type. |
| * |
| * For example, suppose there is an enum type |
| * <pre> |
| * enum Fruit { APPLE, ORANGE, GRAPE } |
| * </pre> |
| * An {@link EnumCounters} object can be created for counting the numbers of |
| * APPLE, ORANGLE and GRAPE. |
| * |
| * @param <E> the enum type |
| */ |
| public class EnumCounters<E extends Enum<E>> { |
| /** An array of enum constants. */ |
| private final E[] enumConstants; |
| /** The counter array, counters[i] corresponds to the enumConstants[i]. */ |
| private final long[] counters; |
| |
| /** |
| * Construct counters for the given enum constants. |
| * @param enumConstants an array of enum constants such that, |
| * for all i, enumConstants[i].ordinal() == i. |
| */ |
| public EnumCounters(final E[] enumConstants) { |
| for(int i = 0; i < enumConstants.length; i++) { |
| Preconditions.checkArgument(enumConstants[i].ordinal() == i); |
| } |
| this.enumConstants = enumConstants; |
| this.counters = new long[enumConstants.length]; |
| } |
| |
| /** @return the value of counter e. */ |
| public final long get(final E e) { |
| return counters[e.ordinal()]; |
| } |
| |
| /** Negate all counters. */ |
| public final void negation() { |
| for(int i = 0; i < counters.length; i++) { |
| counters[i] = -counters[i]; |
| } |
| } |
| |
| /** Set counter e to the given value. */ |
| public final void set(final E e, final long value) { |
| counters[e.ordinal()] = value; |
| } |
| |
| /** Add the given value to counter e. */ |
| public final void add(final E e, final long value) { |
| counters[e.ordinal()] += value; |
| } |
| |
| /** Add that counters to this counters. */ |
| public final void add(final EnumCounters<E> that) { |
| for(int i = 0; i < counters.length; i++) { |
| this.counters[i] += that.counters[i]; |
| } |
| } |
| |
| /** Subtract the given value from counter e. */ |
| public final void subtract(final E e, final long value) { |
| counters[e.ordinal()] -= value; |
| } |
| |
| /** Subtract that counters from this counters. */ |
| public final void subtract(final EnumCounters<E> that) { |
| for(int i = 0; i < counters.length; i++) { |
| this.counters[i] -= that.counters[i]; |
| } |
| } |
| |
| @Override |
| public String toString() { |
| final StringBuilder b = new StringBuilder(); |
| for(int i = 0; i < counters.length; i++) { |
| final String name = enumConstants[i].name(); |
| b.append(name).append("=").append(counters[i]).append(", "); |
| } |
| return b.substring(0, b.length() - 2); |
| } |
| |
| /** |
| * A factory for creating counters. |
| * |
| * @param <E> the enum type |
| * @param <C> the counter type |
| */ |
| public static interface Factory<E extends Enum<E>, |
| C extends EnumCounters<E>> { |
| /** Create a new counters instance. */ |
| public C newInstance(); |
| } |
| |
| /** |
| * A key-value map which maps the keys to {@link EnumCounters}. |
| * Note that null key is supported. |
| * |
| * @param <K> the key type |
| * @param <E> the enum type |
| * @param <C> the counter type |
| */ |
| public static class Map<K, E extends Enum<E>, C extends EnumCounters<E>> { |
| /** The factory for creating counters. */ |
| private final Factory<E, C> factory; |
| /** Key-to-Counts map. */ |
| private final java.util.Map<K, C> counts = new HashMap<K, C>(); |
| |
| /** Construct a map. */ |
| public Map(final Factory<E, C> factory) { |
| this.factory = factory; |
| } |
| |
| /** @return the counters for the given key. */ |
| public final C getCounts(final K key) { |
| C c = counts.get(key); |
| if (c == null) { |
| c = factory.newInstance(); |
| counts.put(key, c); |
| } |
| return c; |
| } |
| |
| /** @return the sum of the values of all the counters. */ |
| public final C sum() { |
| final C sum = factory.newInstance(); |
| for(C c : counts.values()) { |
| sum.add(c); |
| } |
| return sum; |
| } |
| |
| /** @return the sum of the values of all the counters for e. */ |
| public final long sum(final E e) { |
| long sum = 0; |
| for(C c : counts.values()) { |
| sum += c.get(e); |
| } |
| return sum; |
| } |
| |
| @Override |
| public String toString() { |
| return counts.toString(); |
| } |
| } |
| } |