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.bookkeeper.common.util;
  
  import java.util.concurrent.Future;
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.concurrent.ScheduledFuture;
  import java.util.concurrent.ScheduledThreadPoolExecutor;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.TimeUnit;
  import lombok.extern.slf4j.Slf4j;
  
  @Slf4j
  public class SingleThreadSafeScheduledExecutorService extends ScheduledThreadPoolExecutor
          implements ScheduledExecutorService {
  
      public SingleThreadSafeScheduledExecutorService(ThreadFactory threadFactory) {
          super(1, threadFactory);
      }
  
      private static final class SafeRunnable implements Runnable {
          private final Runnable task;
  
          SafeRunnable(Runnable task) {
              this.task = task;
          }
  
          @Override
          public void run() {
              try {
                  task.run();
              } catch (Throwable t) {
                  log.warn("Unexpected throwable from task {}: {}", task.getClass(), t.getMessage(), t);
              }
          }
      }
  
      @Override
      public ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
          return super.schedule(new SafeRunnable(command), delay, unit);
      }
  
      @Override
      public ScheduledFuture<?> scheduleAtFixedRate(Runnable command,
                                                    long initialDelay, long period, TimeUnit unit) {
          return super.scheduleAtFixedRate(new SafeRunnable(command), initialDelay, period, unit);
      }
  
      @Override
      public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command,
                                                       long initialDelay, long delay, TimeUnit unit) {
          return super.scheduleWithFixedDelay(new SafeRunnable(command), initialDelay, delay, unit);
      }
  
      @Override
      public Future<?> submit(Runnable task) {
          return super.submit(new SafeRunnable(task));
      }
  }
  