WatchCallback.java

// Copyright 2016 Twitter. All rights reserved.
//
// 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.twitter.heron.spi.statemgr;

/**
 * A callback interface used to set a watch on any of the nodes
 * in certain implemenations of IStateManager (Zookeeper for example)
 * Any event on that node will trigger the callback (processWatch).
 */
public interface WatchCallback {

  /**
   * When watch is triggered, process it
   *
   * @param path the node path
   * @param eventType the WatchEventType
   */
  void processWatch(String path, WatchEventType eventType);

  enum WatchEventType {
    None,
    NodeCreated,
    NodeDeleted,
    NodeDataChanged,
    NodeChildrenChanged;
  }
}