//******************************************************************************************************//  StateMachine.cs - Gbtc////  Copyright © 2016, Grid Protection Alliance.  All Rights Reserved.////  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See//  the NOTICE file distributed with this work for additional information regarding copyright ownership.//  The GPA licenses this file to you under the Eclipse Public License -v 1.0 (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.opensource.org/licenses/eclipse-1.0.php////  Unless agreed to in writing, the subject software distributed under the License is distributed on an//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the//  License for the specific language governing permissions and limitations.////  Code Modification History://  ----------------------------------------------------------------------------------------------------//  10/24/2016 - Steven E. Chisholm//       Generated original version of source code. //       ////****************************************************************************************************** using System.Threading;#pragma warning disable 420 namespace GSF.Threading{    /// <summary>    /// Helps facilitate a multithreaded state machine.    /// </summary>    /// <remarks>    /// State machine variables must be integers since <see cref="Interlocked"/> methods require premitive types.    /// </remarks>    public class StateMachine    {        private volatile int m_state;         /// <summary>        /// Creates a new <see cref="StateMachine"/>        /// </summary>        /// <param name="initialState">the state to initially set to</param>        public StateMachine(int initialState)        {            m_state = initialState;        }         /// <summary>        /// Attempts to change the state of this machine from <see param="prevState"/> to <see param="nextState"/>.        /// </summary>        /// <param name="prevState">The state to change from</param>        /// <param name="nextState">The state to change to</param>        /// <returns>True if the state changed from the previous state to the next state.         /// False if unsuccessful.</returns>        public bool TryChangeState(int prevState, int nextState)        {            return (m_state == prevState && Interlocked.CompareExchange(ref m_state, nextState, prevState) == prevState);        }         /// <summary>        /// Gets the current state of the State Machine.         /// </summary>        public int State        {            get            {                return m_state;            }        }         /// <summary>        /// Sets the value of the state.        /// </summary>        /// <param name="state"></param>        public void SetState(int state)        {            m_state = state;        }         /// <summary>        /// Implicitly conversion of the state to the integer value of the state.        /// </summary>        /// <param name="machine"></param>        /// <returns></returns>        public static implicit operator int(StateMachine machine)        {            return machine.State;        }    }}