/*
 * 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.
 */

using System;

namespace Apache.NMS.Util
{
    public class AtomicReference<T>
    {
        protected T atomicValue;

        public T Value
        {
            get
            {
                lock (this)
                {
                    return atomicValue;
                }
            }
            set
            {
                lock (this)
                {
                    atomicValue = value;
                }
            }
        }

        public AtomicReference()
        {
            atomicValue = default(T);
        }

        public AtomicReference(T defaultValue)
        {
            atomicValue = defaultValue;
        }

        public T GetAndSet(T value)
        {
            lock (this)
            {
                T ret = atomicValue;
                atomicValue = value;
                return ret;
            }
        }
    }

    public class Atomic<T> : AtomicReference<T> where T : IComparable
    {
        public Atomic() : base()
        {
        }

        public Atomic(T defaultValue) : base(defaultValue)
        {
        }

        public bool CompareAndSet(T expected, T newValue)
        {
            lock (this)
            {
                if (0 == atomicValue.CompareTo(expected))
                {
                    atomicValue = newValue;
                    return true;
                }

                return false;
            }
        }
    }
}