DP44/Common/DTS.Common/Utils/SecureQueue.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Windows.Forms;
using DTS.Common.Utilities.Logging;

namespace DTS.Common.Utils
{
    public class SecureQueue<T> : IDisposable where T : new()
    {
        public enum NullPolicy
        {
            DenyNull, // throw an exception if try to Enqueue null or zero length
            SkipNull, // don't complain but don't enqueue null or zero length
            AllowNull // let null's in too
        }

        protected Queue<T[]> ByteQueue;
        protected object ByteQueueLock;
        protected ManualResetEvent ByteQueueEvent;
        protected NullPolicy _NullPolicy;
        protected string Name;
        protected Stopwatch StopWatch;

        public SecureQueue(NullPolicy policy, string name)
        {
            StopWatch = new Stopwatch();
            StopWatch.Start();
            ByteQueue = new Queue<T[]>();
            ByteQueueLock = new object();
            ByteQueueEvent = new ManualResetEvent(false);
            _NullPolicy = policy;
            Name = name;
        }

        public void ResetEvent()
        {
            //latestReset = GetCaller();
            ByteQueueEvent.Reset();
        }

        public void Enqueue(T[] newData)
        {
            try
            {
                lock (ByteQueueLock)
                {
                    if (newData == null || newData.Length == 0)
                    {
                        switch (_NullPolicy)
                        {
                            case NullPolicy.DenyNull:
                                throw new ArgumentException("SecureQueue_Enqueue_Err1");
                            case NullPolicy.SkipNull:
                                return;
                        }
                    }
                    ByteQueue.Enqueue((T[])newData?.Clone());
                    if (Enums.DASFactory.DFConstantsAndEnums.ExtraCommunicationLogging)
                    {
                        APILogger.Log("Enqueing data", newData);
                    }
                    ByteQueueEvent.Set();
                }
            }
            catch (Exception ex)
            {
                APILogger.LogString("SecureQueue.Enqueue: The queue(" + Name + ") threw an exception. " + ex.Message + " " + ex.StackTrace);
                throw;
            }
        }

        /// <summary>
        /// Wait for TimeoutMillisec milliseconds for data to arrive in the buffer. Returns false if it times out.
        /// </summary>
        /// <param name="timeoutMillisec"></param>
        /// <returns>true if data has arrived, false if it times out</returns>
        public bool WaitForData(int timeoutMillisec)
        {
            try
            {
                var result = ByteQueueEvent.WaitOne(timeoutMillisec, false);
                return result;
            }
            catch (Exception ex)
            {
                APILogger.LogString("SecureQueue.WaitForData: The queue(" + Name + ") threw an exception. " + ex.Message + " " + ex.StackTrace);
            }
            return false;
        }

        public WaitHandle QueueWaitHandle => ByteQueueEvent;

        public T[] Dequeue(bool resetEvent)
        {
            try
            {
                lock (ByteQueueLock)
                {
                    ByteQueueEvent = new ManualResetEvent(false);

                    if (ByteQueue.Count == 0)
                    {
                        return new T[0];
                    }
                    if (ByteQueue.Count == 1)
                    {
                        var ret = ByteQueue.Dequeue();
                        return ret;
                    }

                    // count how much data we have
                    var totalBytes = ByteQueue.Sum(arr => arr.Length);
                    if (totalBytes == 0)
                    {
                        APILogger.LogString("SecureQueue.Dequeue: The queue(" + Name + ") has 0 bytes!");
                    }
                    // allocate that much
                    var result = new T[totalBytes];
                    var index = 0;
                    // now make one large array
                    while (ByteQueue.Any())
                    {
                        var element = ByteQueue.Dequeue();
                        Array.Copy(element, 0, result, index, element.Length);
                        index += element.Length;
                    }
                    return result;
                }
            }
            catch (Exception ex)
            {
                APILogger.LogString("SecureQueue.Dequeue: The queue(" + Name + ") threw an exception. " + ex.Message + " " + ex.StackTrace);
            }
            return new T[0];
        }

        public void Flush()
        {
            try
            {
                lock (ByteQueueLock)
                {
                    //latestFlush = GetCaller();
                    ByteQueueEvent = new ManualResetEvent(false);
                    ByteQueue.Clear();
                }
            }
            catch (Exception ex)
            {
                APILogger.LogString("SecureQueue.Flush: The queue(" + Name + ") threw an exception. " + ex.Message + " " + ex.StackTrace);
            }
        }

        public bool IsEmpty()
        {
            return ByteQueue.Count == 0;
        }

        public void Dispose()
        {
        }
    }
}