| /* |
| * 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.cassandra.utils; |
| |
| import java.util.concurrent.atomic.AtomicLongArray; |
| |
| import org.junit.Test; |
| |
| import static org.junit.Assert.assertArrayEquals; |
| |
| public class HistogramBuilderTest |
| { |
| |
| @Test |
| public void testStdevEmpty() |
| { |
| EstimatedHistogram hist = new HistogramBuilder().buildWithStdevRangesAroundMean(); |
| assertArrayEquals(new long[] { }, hist.getBucketOffsets()); |
| assertArrayEquals(new long[] { 0 }, toArray(hist.buckets)); |
| } |
| |
| @Test |
| public void testStdevSingletonRanges() |
| { |
| EstimatedHistogram hist; |
| hist = new HistogramBuilder(new long[] { 5, 5, 5, 5, 5 }).buildWithStdevRangesAroundMean(); |
| assertArrayEquals(new long[] { 4, 5 }, hist.getBucketOffsets()); |
| assertArrayEquals(new long[] { 0, 5, 0 }, toArray(hist.buckets)); |
| // should behave exactly the same for negative numbers |
| hist = new HistogramBuilder(new long[] { -1 }).buildWithStdevRangesAroundMean(); |
| assertArrayEquals(new long[] { -2, -1 }, hist.getBucketOffsets()); |
| assertArrayEquals(new long[] { 0, 1, 0 }, toArray(hist.buckets)); |
| } |
| |
| @Test |
| public void testStdevNearZeroStdev() |
| { |
| EstimatedHistogram hist; |
| long[] vals = new long[100000]; |
| vals[0] = 99; |
| vals[1] = 101; |
| for (int i = 2 ; i < vals.length ; i++) |
| vals[i] = 100; |
| hist = new HistogramBuilder(vals).buildWithStdevRangesAroundMean(); |
| assertArrayEquals(new long[] { 98, 99, 100, 101 }, hist.getBucketOffsets()); |
| assertArrayEquals(new long[] { 0, 1, vals.length - 2, 1, 0 }, toArray(hist.buckets)); |
| } |
| |
| @Test |
| public void testStdev() |
| { |
| long[] vals; |
| EstimatedHistogram hist; |
| vals = new long[] { -10, -3, -2, -2, -1, -1, -1, -1, -1, -1, -1, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 10 }; |
| hist = new HistogramBuilder(vals).buildWithStdevRangesAroundMean(2); |
| assertArrayEquals(new long[] { -11, -6, -3, 0, 3, 6, 10 }, hist.getBucketOffsets()); |
| assertArrayEquals(new long[] { 0, 1, 1, 10, 10, 0, 1, 0 }, toArray(hist.buckets)); |
| } |
| |
| private static long[] toArray(AtomicLongArray a) |
| { |
| final long[] r = new long[a.length()]; |
| for (int i = 0 ; i < r.length ; i++) |
| r[i] = a.get(i); |
| return r; |
| } |
| |
| @Test |
| public void testStdevLargeNumbers() |
| { |
| long[] vals; |
| EstimatedHistogram hist; |
| vals = new long[100000]; |
| for (int i = 0 ; i < vals.length ; i++) |
| { |
| if (i < vals.length * 0.6f) |
| vals[i] = 60; |
| else if (i < vals.length * 0.8f) |
| vals[i] = 120; |
| else if (i < vals.length * 0.9f) |
| vals[i] = 180; |
| else if (i < vals.length * 0.95f) |
| vals[i] = 240; |
| else if (i < vals.length * 0.98f) |
| vals[i] = 320; |
| else |
| vals[i] = 1000; |
| } |
| hist = new HistogramBuilder(vals).buildWithStdevRangesAroundMean(2); |
| assertArrayEquals(new long[] { 59, 120, 260, 400, 1000 }, hist.getBucketOffsets()); |
| assertArrayEquals(new long[] { 0, 80000, 15000, 3000, 2000, 0 }, toArray(hist.buckets)); |
| } |
| |
| } |