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.connect.integration;
  
  import org.apache.kafka.common.utils.Time;
  
  import java.util.List;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.TimeUnit;
  import java.util.function.Consumer;
  
  /**
   * A latch that can be used to count down the number of times a connector and/or tasks have
   * been started and stopped.
   */
  public class StartAndStopLatch {
      private final CountDownLatch startLatch;
      private final CountDownLatch stopLatch;
      private final List<StartAndStopLatch> dependents;
      private final Consumer<StartAndStopLatch> uponCompletion;
      private final Time clock;
  
      StartAndStopLatch(int expectedStarts, int expectedStops, Consumer<StartAndStopLatch> uponCompletion,
                   List<StartAndStopLatch> dependents, Time clock) {
          this.startLatch = new CountDownLatch(Math.max(expectedStarts, 0));
          this.stopLatch = new CountDownLatch(Math.max(expectedStops, 0));
          this.dependents = dependents;
          this.uponCompletion = uponCompletion;
          this.clock = clock;
      }
  
      protected void recordStart() {
          startLatch.countDown();
      }
  
      protected void recordStop() {
          stopLatch.countDown();
      }
  
      /**
       * Causes the current thread to wait until the latch has counted down the starts and
       * stops to zero, unless the thread is {@linkplain Thread#interrupt interrupted},
       * or the specified waiting time elapses.
       *
       * <p>If the current counts are zero then this method returns immediately
       * with the value {@code true}.
       *
       * <p>If the current count is greater than zero then the current
       * thread becomes disabled for thread scheduling purposes and lies
       * dormant until one of three things happen:
       * <ul>
       * <li>The counts reach zero due to invocations of the {@link #recordStart()} and
       * {@link #recordStop()} methods; or
       * <li>Some other thread {@linkplain Thread#interrupt interrupts}
       * the current thread; or
       * <li>The specified waiting time elapses.
       * </ul>
       *
       * <p>If the count reaches zero then the method returns with the
       * value {@code true}.
       *
       * <p>If the current thread:
       * <ul>
       * <li>has its interrupted status set on entry to this method; or
       * <li>is {@linkplain Thread#interrupt interrupted} while waiting,
       * </ul>
       * then {@link InterruptedException} is thrown and the current thread's
       * interrupted status is cleared.
       *
       * <p>If the specified waiting time elapses then the value {@code false}
       * is returned.  If the time is less than or equal to zero, the method
       * will not wait at all.
       *
       * @param timeout the maximum time to wait
       * @param unit    the time unit of the {@code timeout} argument
       * @return {@code true} if the counts reached zero and {@code false}
       *         if the waiting time elapsed before the counts reached zero
       * @throws InterruptedException if the current thread is interrupted
       *         while waiting
       */
      public boolean await(long timeout, TimeUnit unit) throws InterruptedException {
          final long start = clock.milliseconds();
          final long end = start + unit.toMillis(timeout);
          if (!startLatch.await(end - start, TimeUnit.MILLISECONDS)) {
              return false;
          }
          if (!stopLatch.await(end - clock.milliseconds(), TimeUnit.MILLISECONDS)) {
              return false;
          }
  
          if (dependents != null) {
              for (StartAndStopLatch dependent : dependents) {
                  if (!dependent.await(end - clock.milliseconds(), TimeUnit.MILLISECONDS)) {
                      return false;
                  }
              }
          }
          if (uponCompletion != null) {
              uponCompletion.accept(this);
          }
          return true;
      }
  }
  