content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed 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 com.alibaba.nacos.sys.file;
  
  import java.nio.file.WatchEvent;
  import java.util.concurrent.Executor;
  
  /**
   * file watcher.
   *
   * @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
   */
  @SuppressWarnings("PMD.AbstractClassShouldStartWithAbstractNamingRule")
  public abstract class FileWatcher {
      
      /**
       * Triggered when a file change occurs.
       *
       * @param event {@link FileChangeEvent}
       */
      public abstract void onChange(FileChangeEvent event);
      
      /**
       * WatchEvent context information.
       *
       * @param context {@link WatchEvent#context()}
       * @return is this watcher interest context
       */
      public abstract boolean interest(String context);
      
      /**
       * If the FileWatcher has its own thread pool, use this thread pool to execute, otherwise use the WatchFileManager
       * thread.
       *
       * @return {@link Executor}
       */
      public Executor executor() {
          return null;
      }
      
  }
  