| /* |
| * 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.jackrabbit.oak.plugins.index; |
| |
| import org.junit.Test; |
| |
| import java.util.Random; |
| |
| import static org.junit.Assert.assertEquals; |
| import static org.junit.Assert.assertTrue; |
| |
| public class ApproximateCounterTest { |
| |
| @Test |
| public void veryHighResolution() { |
| for (int i = -100; i < 100; i++) { |
| assertEquals(i, ApproximateCounter.calculateOffset(i, -1)); |
| assertEquals(i, ApproximateCounter.calculateOffset(i, 0)); |
| assertEquals(i, ApproximateCounter.calculateOffset(i, 1)); |
| } |
| } |
| |
| @Test |
| public void regularResolution() { |
| ApproximateCounter.setSeed(0); |
| long result = 0; |
| long count = 100000; |
| int nonZero = 0; |
| for (long i = 0; i < count; i++) { |
| long offset = ApproximateCounter.calculateOffset(1, 1000); |
| if (offset != 0) { |
| nonZero++; |
| result += offset; |
| } |
| } |
| // most of the time, 0 needs to be returned |
| assertTrue(nonZero < count / 500); |
| // the expected result is within a certain range |
| assertTrue(Math.abs(result - count) < count / 10); |
| } |
| |
| @Test |
| public void addRemove() { |
| ApproximateCounter.setSeed(0); |
| Random r = new Random(1); |
| long result = 0; |
| long exactResult = 0; |
| long count = 100000; |
| long sumChange = 0; |
| int nonZero = 0; |
| for (long i = 0; i < count; i++) { |
| int o = r.nextInt(20) - 10; |
| exactResult += o; |
| sumChange += Math.abs(o); |
| long offset = ApproximateCounter.calculateOffset(o, 1000); |
| if (offset != 0) { |
| nonZero++; |
| result += offset; |
| } |
| } |
| // most of the time, 0 needs to be returned |
| assertTrue(nonZero < count / 50); |
| // the expected result is within a certain range |
| assertTrue(Math.abs(result - exactResult) < sumChange / 10); |
| } |
| |
| @Test |
| public void lowResolution() { |
| ApproximateCounter.setSeed(0); |
| long result = 0; |
| long count = 100000; |
| int nonZero = 0; |
| for (long i = 0; i < count; i++) { |
| long offset = ApproximateCounter.calculateOffset(1, 100); |
| if (offset != 0) { |
| offset = ApproximateCounter.adjustOffset(result, offset, 100); |
| } |
| if (offset != 0) { |
| nonZero++; |
| result += offset; |
| } |
| } |
| // most of the time, 0 needs to be returned |
| assertTrue(nonZero < count / 500); |
| // the expected result is within a certain range |
| assertTrue(Math.abs(result - count) < count / 10); |
| } |
| |
| @Test |
| public void keepAboveZero() { |
| // adjustOffset ensures that the resulting count is larger or equal to 0 |
| assertEquals(1234, ApproximateCounter.adjustOffset(-1234, -100, 10)); |
| } |
| |
| @Test |
| public void highResolutionAdjust() { |
| // adjustOffset with resolution of 1 should not affect the result |
| for (int i = 0; i < 10; i++) { |
| assertEquals(123, ApproximateCounter.adjustOffset(i, 123, 1)); |
| } |
| } |
| |
| } |