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.server.util.ShutdownableThread;
  
  /**
   * SystemTimerReaper wraps a {@link Timer} and starts a reaper thread
   * to expire the tasks in the {@link Timer}.
   */
  public class SystemTimerReaper implements Timer {
      private static final long WORK_TIMEOUT_MS = 200L;
  
      class Reaper extends ShutdownableThread {
          Reaper(String name) {
              super(name, false);
          }
  
          @Override
          public void doWork() {
              try {
                  timer.advanceClock(WORK_TIMEOUT_MS);
              } catch (InterruptedException ex) {
                  // Ignore.
              }
          }
      }
  
      private final Timer timer;
      private final Reaper reaper;
  
      public SystemTimerReaper(String reaperThreadName, Timer timer) {
          this.timer = timer;
          this.reaper = new Reaper(reaperThreadName);
          this.reaper.start();
      }
  
      @Override
      public void add(TimerTask timerTask) {
          timer.add(timerTask);
      }
  
      @Override
      public boolean advanceClock(long timeoutMs) throws InterruptedException {
          return timer.advanceClock(timeoutMs);
      }
  
      @Override
      public int size() {
          return timer.size();
      }
  
      @Override
      public void close() throws Exception {
          reaper.initiateShutdown();
          // Improve shutdown time by waking up the reaper thread
          // blocked on poll by sending a no-op.
          timer.add(new TimerTask(0) {
              @Override
              public void run() {}
          });
          reaper.awaitShutdown();
          timer.close();
      }
  
      // visible for testing
      boolean isShutdown() {
          return reaper.isShutdownComplete();
      }
  }
  