content: /*
   * 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.kafka.common.record;
  
  import org.junit.jupiter.api.Test;
  
  import java.util.Arrays;
  import java.util.List;
  
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  public class CompressionRatioEstimatorTest {
  
      @Test
      public void testUpdateEstimation() {
          class EstimationsObservedRatios {
              final float currentEstimation;
              final float observedRatio;
              EstimationsObservedRatios(float currentEstimation, float observedRatio) {
                  this.currentEstimation = currentEstimation;
                  this.observedRatio = observedRatio;
              }
          }
  
          // If currentEstimation is smaller than observedRatio, the updatedCompressionRatio is currentEstimation plus
          // COMPRESSION_RATIO_DETERIORATE_STEP 0.05, otherwise currentEstimation minus COMPRESSION_RATIO_IMPROVING_STEP
          // 0.005. There are four cases,and updatedCompressionRatio shouldn't smaller than observedRatio in all of cases.
          // Refer to non test code for more details.
          List<EstimationsObservedRatios> estimationsObservedRatios = Arrays.asList(
              new EstimationsObservedRatios(0.8f, 0.84f),
              new EstimationsObservedRatios(0.6f, 0.7f),
              new EstimationsObservedRatios(0.6f, 0.4f),
              new EstimationsObservedRatios(0.004f, 0.001f));
          for (EstimationsObservedRatios estimationsObservedRatio : estimationsObservedRatios) {
              String topic = "tp";
              CompressionRatioEstimator.setEstimation(topic, CompressionType.ZSTD, estimationsObservedRatio.currentEstimation);
              float updatedCompressionRatio = CompressionRatioEstimator.updateEstimation(topic, CompressionType.ZSTD, estimationsObservedRatio.observedRatio);
              assertTrue(updatedCompressionRatio >= estimationsObservedRatio.observedRatio);
          }
      }
  }
  