/*
 * 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
 *
 *      https://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.commons.lang3.concurrent;

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.util.concurrent.atomic.AtomicReference;

/**
 * Base class for circuit breakers.
 *
 * @param <T> the type of the value monitored by this circuit breaker
 * @since 3.5
 */
public abstract class AbstractCircuitBreaker<T> implements CircuitBreaker<T> {

    /**
     * Enumerates the different states of a circuit breaker. This class also contains some logic for performing state transitions. This is done to avoid complex
     * if-conditions in the code of {@link CircuitBreaker}.
     */
    protected enum State {

        /** The closed state. */
        CLOSED {

            /**
             * {@inheritDoc}
             */
            @Override
            public State oppositeState() {
                return OPEN;
            }
        },

        /** The open state. */
        OPEN {
