/*
 * 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.nemo.runtime.common.metric;

import java.io.Serializable;
import java.util.List;

/**
 * Interface for metric which contians its state.
 *
 * @param <T> class of state of the metric.
 */
public interface StateMetric<T extends Serializable> extends Metric {
  /**
   * Get its list of {@link StateTransitionEvent}.
   *
   * @return list of events.
   */
  List<StateTransitionEvent<T>> getStateTransitionEvents();

  /**
   * Add a {@link StateTransitionEvent} to the metric.
   *
   * @param prevState previous state.
   * @param newState  new state.
   */
  void addEvent(T prevState, T newState);
}