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.server.util.timer;
  
  import org.apache.kafka.common.utils.Time;
  import org.apache.kafka.test.TestUtils;
  
  import org.junit.jupiter.api.AfterEach;
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.stream.Collectors;
  import java.util.stream.IntStream;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.junit.jupiter.api.Assertions.fail;
  
  public class TimerTest {
  
      private static class TestTask extends TimerTask {
          final int id;
          final CountDownLatch latch;
          final List<Integer> output;
          final AtomicBoolean completed = new AtomicBoolean(false);
  
          TestTask(
              long delayMs,
              int id,
              CountDownLatch latch,
              List<Integer> output
          ) {
              super(delayMs);
              this.id = id;
              this.latch = latch;
              this.output = output;
          }
  
          @Override
          public void run() {
              if (completed.compareAndSet(false, true)) {
                  synchronized (output) {
                      output.add(id);
                  }
                  latch.countDown();
              }
          }
      }
  
      private SystemTimer timer = null;
  
      @BeforeEach
      public void setup() {
          timer = new SystemTimer("test", 1, 3, Time.SYSTEM.hiResClockMs());
      }
  
      @AfterEach
      public void teardown() throws Exception {
          timer.close();
          TestUtils.waitForCondition(timer::isTerminated, "timer executor not terminated");
      }
  
      @Test
      public void testAlreadyExpiredTask() throws InterruptedException {
          List<Integer> output = new ArrayList<>();
  
          List<CountDownLatch> latches = IntStream.range(-5, 0).mapToObj(i -> {
              CountDownLatch latch = new CountDownLatch(1);
              timer.add(new TestTask(i, i, latch, output));
              return latch;
          }).collect(Collectors.toList());
  
          timer.advanceClock(0L);
  
          latches.stream().limit(5).forEach(latch -> {
              try {
                  assertTrue(latch.await(3, TimeUnit.SECONDS),
                      "already expired tasks should run immediately");
              } catch (InterruptedException e) {
                  fail("interrupted");
              }
          });
  
          assertEquals(Set.of(-5, -4, -3, -2, -1), new HashSet<>(output),
              "output of already expired tasks");
      }
  
      @Test
      public void testTaskExpiration() throws InterruptedException {
          List<Integer> output = new ArrayList<>();
          List<TestTask> tasks = new ArrayList<>();
          List<Integer> ids = new ArrayList<>();
          List<CountDownLatch> latches = new ArrayList<>();
  
          IntStream.range(0, 5).forEach(i -> {
              CountDownLatch latch = new CountDownLatch(1);
              tasks.add(new TestTask(i, i, latch, output));
              ids.add(i);
              latches.add(latch);
          });
  
          IntStream.range(10, 100).forEach(i -> {
              CountDownLatch latch = new CountDownLatch(2);
              tasks.add(new TestTask(i, i, latch, output));
              tasks.add(new TestTask(i, i, latch, output));
              ids.add(i);
              ids.add(i);
              latches.add(latch);
          });
  
          IntStream.range(100, 500).forEach(i -> {
              CountDownLatch latch = new CountDownLatch(1);
              tasks.add(new TestTask(i, i, latch, output));
              ids.add(i);
              latches.add(latch);
          });
  
          // randomly submit requests
          tasks.forEach(task -> timer.add(task));
  
          while (timer.advanceClock(2000)) { }
  
          latches.forEach(latch -> {
              try {
                  latch.await();
              } catch (InterruptedException e) {
                  fail("interrupted");
              }
          });
  
          assertEquals(ids, output.stream().sorted().collect(Collectors.toList()),
              "output should match");
      }
  }
  