// 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.api.topology;

import com.twitter.heron.classification.InterfaceAudience;
import com.twitter.heron.classification.InterfaceStability;

/**
 * Bolt or spout instances should implement this method if they wish to be informed of changed to
 * the topology context during the lifecycle of the instance. The TopologyContext is backed by
 * elements of the physical plan, which can change during a scaling event. Instances that need to
 * adapt to such changes should implement this interface to receive a callback when a change occurs.
 */
@InterfaceAudience.Public
@InterfaceStability.Evolving
public interface IUpdatable {
  void update(TopologyContext topologyContext);
}
