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.asterix.external.feed.watch;
  
  import java.util.Objects;
  
  import org.apache.asterix.active.IActiveEntityEventSubscriber;
  import org.apache.asterix.active.IActiveEntityEventsListener;
  import org.apache.hyracks.util.Span;
  
  public abstract class AbstractSubscriber implements IActiveEntityEventSubscriber {
  
      protected final IActiveEntityEventsListener listener;
      private final Object lockObject;
      private volatile boolean done = false;
      private volatile Exception failure = null;
  
      public AbstractSubscriber(IActiveEntityEventsListener listener, Object lockObject) {
          Objects.requireNonNull(lockObject);
          this.listener = listener;
          this.lockObject = lockObject;
      }
  
      public AbstractSubscriber(IActiveEntityEventsListener listener) {
          this.listener = listener;
          this.lockObject = this;
      }
  
      @Override
      public boolean isDone() {
          return done;
      }
  
      public void complete(Exception failure) {
          synchronized (lockObject) {
              if (failure != null) {
                  this.failure = failure;
              }
              done = true;
              lockObject.notifyAll();
          }
      }
  
      @Override
      public void sync() throws InterruptedException {
          synchronized (lockObject) {
              while (!done) {
                  lockObject.wait();
              }
          }
      }
  
      public boolean sync(Span span) throws InterruptedException {
          synchronized (lockObject) {
              while (!done) {
                  span.wait(lockObject);
                  if (done || span.elapsed()) {
                      return done;
                  }
              }
              return done;
          }
      }
  
      public Exception getFailure() {
          return failure;
      }
  
      protected void reset() {
          synchronized (lockObject) {
              done = false;
              failure = null;
          }
      }
  }
  