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.metrics;
  
  import org.apache.kafka.common.metrics.stats.TokenBucket;
  import org.apache.kafka.common.utils.MockTime;
  import org.apache.kafka.common.utils.Time;
  
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  import java.util.concurrent.TimeUnit;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  
  public class TokenBucketTest {
      Time time;
  
      @BeforeEach
      public void setup() {
          time = new MockTime(0, System.currentTimeMillis(), System.nanoTime());
      }
  
      @Test
      public void testRecord() {
          // Rate  = 5 unit / sec
          // Burst = 2 * 10 = 20 units
          MetricConfig config = new MetricConfig()
              .quota(Quota.upperBound(5))
              .timeWindow(2, TimeUnit.SECONDS)
              .samples(10);
  
          TokenBucket tk = new TokenBucket();
  
          // Expect 100 credits at T
          assertEquals(100, tk.measure(config, time.milliseconds()), 0.1);
  
          // Record 60 at T, expect 13 credits
          tk.record(config, 60, time.milliseconds());
          assertEquals(40, tk.measure(config, time.milliseconds()), 0.1);
  
          // Advance by 2s, record 5, expect 45 credits
          time.sleep(2000);
          tk.record(config, 5, time.milliseconds());
          assertEquals(45, tk.measure(config, time.milliseconds()), 0.1);
  
          // Advance by 2s, record 60, expect -5 credits
          time.sleep(2000);
          tk.record(config, 60, time.milliseconds());
          assertEquals(-5, tk.measure(config, time.milliseconds()), 0.1);
      }
  
      @Test
      public void testUnrecord() {
          // Rate  = 5 unit / sec
          // Burst = 2 * 10 = 20 units
          MetricConfig config = new MetricConfig()
              .quota(Quota.upperBound(5))
              .timeWindow(2, TimeUnit.SECONDS)
              .samples(10);
  
          TokenBucket tk = new TokenBucket();
  
          // Expect 100 credits at T
          assertEquals(100, tk.measure(config, time.milliseconds()), 0.1);
  
          // Record -60 at T, expect 100 credits
          tk.record(config, -60, time.milliseconds());
          assertEquals(100, tk.measure(config, time.milliseconds()), 0.1);
  
          // Advance by 2s, record 60, expect 40 credits
          time.sleep(2000);
          tk.record(config, 60, time.milliseconds());
          assertEquals(40, tk.measure(config, time.milliseconds()), 0.1);
  
          // Advance by 2s, record -60, expect 100 credits
          time.sleep(2000);
          tk.record(config, -60, time.milliseconds());
          assertEquals(100, tk.measure(config, time.milliseconds()), 0.1);
      }
  }
  