//******************************************************************************************************//  StatisticValueStateCache.cs - Gbtc////  Copyright © 2012, 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 MIT License (MIT), 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/MIT////  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://  ----------------------------------------------------------------------------------------------------//  02/22/2012 - Stephen C. Wills//       Migrated from GSF.PhasorProtocols.//  12/20/2012 - Starlynn Danyelle Gilliam//       Modified Header.////****************************************************************************************************** using System;using System.Collections.Generic;using System.Reflection; namespace GSF.TimeSeries.Statistics{    /// <summary>    /// Caches statistic values to provide the difference between the    /// current and previous values of any statistic given that    /// statistic's source, name, and current value.    /// </summary>    public class StatisticValueStateCache    {        #region [ Members ]         // Fields        private readonly Dictionary<object, Dictionary<string, StatisticValueState>> m_statisticValueStates;         #endregion         #region [ Constructors ]         /// <summary>        /// Creates a new instance of the <see cref="StatisticValueStateCache"/>.        /// </summary>        public StatisticValueStateCache()        {            m_statisticValueStates = new Dictionary<object, Dictionary<string, StatisticValueState>>();        }         #endregion         #region [ Methods ]         /// <summary>        /// Gets the statistical difference between current and previous statistic value.        /// </summary>        /// <param name="source">Source Device.</param>        /// <param name="statistic">Current statistic value.</param>        /// <param name="name">Name of statistic calculation.</param>        /// <returns>Difference from last cached statistic value.</returns>        public double GetDifference(object source, double statistic, string name)        {            lock (m_statisticValueStates)            {                StatisticValueState valueState;                 if (m_statisticValueStates.TryGetValue(source, out Dictionary<string, StatisticValueState> valueStates))                {                    if (valueStates.TryGetValue(name, out valueState))                    {                        valueState.CurrentState = statistic;                        statistic = valueState.GetDifference();                    }                    else                    {                        valueState = new StatisticValueState(name) { PreviousState = statistic };                        valueStates.Add(name, valueState);                    }                }                else                {                    valueStates = new Dictionary<string, StatisticValueState>();                    valueState = new StatisticValueState(name) { PreviousState = statistic };                    valueStates.Add(name, valueState);                     m_statisticValueStates.Add(source, valueStates);                     // Attach to Disposed event of source, if defined                    EventInfo disposedEvent = source.GetType().GetEvent("Disposed");                     if (disposedEvent != null)                        disposedEvent.GetAddMethod().Invoke(source, new object[] { new EventHandler(StatisticSourceDisposed) });                }            }             return statistic;        }         // Remove value states cache when statistic source is disposed        private void StatisticSourceDisposed(object sender, EventArgs e)        {            lock (m_statisticValueStates)                m_statisticValueStates.Remove(sender);        }         #endregion    }}