RandomDelayQueuedSendsAsyncResult.cs source code in C# .NET

                        
Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / NetFx40 / System.ServiceModel.Discovery / System / ServiceModel / Discovery / RandomDelayQueuedSendsAsyncResult.cs / 1305376 / RandomDelayQueuedSendsAsyncResult.cs
                        

                        
                            //---------------------------------------------------------------- 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//---------------------------------------------------------------

namespace System.ServiceModel.Discovery 
{
    using System.Runtime; 
    using System.Threading; 
    using System.Collections.Generic;
 
    abstract class RandomDelayQueuedSendsAsyncResult :
        IteratorAsyncResult>
        where TItem : class
    { 
        readonly InputQueue itemQueue;
        readonly Random random; 
        readonly double maxRandomDelayInMillis; 
        readonly int[] preCalculatedDelays;
        readonly bool doDelay; 

        static AsyncStep dequeueStep;
        static AsyncStep delayStep;
        static AsyncStep sendItemStep; 

        TItem currentItem; 
        int currentDelayIndex; 

        public RandomDelayQueuedSendsAsyncResult( 
            TimeSpan maxRandomDelay,
            InputQueue itemQueue,
            AsyncCallback callback,
            object state) 
            : base(callback, state)
        { 
            Fx.Assert(maxRandomDelay >= TimeSpan.Zero, "The maxRandomDelay parameter must be non negative."); 
            Fx.Assert(itemQueue != null, "The itemQueue parameter must be non null.");
 
            this.itemQueue = itemQueue;

            this.doDelay = maxRandomDelay > TimeSpan.Zero;
            if (this.doDelay) 
            {
                this.random = new Random(); 
                this.maxRandomDelayInMillis = maxRandomDelay.TotalMilliseconds; 

                if (this.itemQueue.PendingCount > 0) 
                {
                    this.preCalculatedDelays = new int[this.itemQueue.PendingCount];
                    this.PreCalculateSendDelays();
                } 
            }
        } 
 
        public IAsyncResult BeginDelay(AsyncCallback callback, object state)
        { 
            return new DelayAsyncResult(this, callback, state);
        }

        public void EndDelay(IAsyncResult result) 
        {
            DelayAsyncResult.End(result); 
        } 

        protected override IEnumerator GetAsyncSteps() 
        {
            while (true)
            {
                yield return RandomDelayQueuedSendsAsyncResult.GetDequeueStep(); 

                if (this.currentItem == null) 
                { 
                    yield break;
                } 

                if (this.doDelay)
                {
                    yield return RandomDelayQueuedSendsAsyncResult.GetDelayStep(); 
                }
 
                yield return RandomDelayQueuedSendsAsyncResult.GetSendItemStep(); 
            }
        } 

        protected void Start(TimeSpan timeout)
        {
            this.Start(this, timeout); 
        }
 
        protected abstract IAsyncResult OnBeginSendItem( 
            TItem item,
            TimeSpan timeout, 
            AsyncCallback callback,
            object state);

        protected abstract void OnEndSendItem(IAsyncResult result); 

        static AsyncStep GetDequeueStep() 
        { 
            if (dequeueStep == null)
            { 
                dequeueStep = RandomDelayQueuedSendsAsyncResult.CallAsync(
                    (thisPtr, t, c, s) => thisPtr.itemQueue.BeginDequeue(TimeSpan.MaxValue, c, s),
                    (thisPtr, r) => thisPtr.currentItem = thisPtr.itemQueue.EndDequeue(r));
            } 

            return dequeueStep; 
        } 

        static AsyncStep GetDelayStep() 
        {
            if (delayStep == null)
            {
                delayStep = RandomDelayQueuedSendsAsyncResult.CallAsync( 
                    (thisPtr, t, c, s) => thisPtr.BeginDelay(c, s),
                    (thisPtr, r) => thisPtr.EndDelay(r)); 
            } 

            return delayStep; 
        }

        static AsyncStep GetSendItemStep()
        { 
            if (sendItemStep == null)
            { 
                sendItemStep = RandomDelayQueuedSendsAsyncResult.CallParallel( 
                    (thisPtr, t, c, s) => thisPtr.OnBeginSendItem(thisPtr.currentItem, t, c, s),
                    (thisPtr, r) => thisPtr.OnEndSendItem(r)); 
            }

            return sendItemStep;
        } 

        void PreCalculateSendDelays() 
        { 
            this.currentDelayIndex = 0;
            for (int i = 0; i < this.preCalculatedDelays.Length; i++) 
            {
                this.preCalculatedDelays[i] = (int)(this.random.NextDouble() * this.maxRandomDelayInMillis);
            }
 
            Array.Sort(this.preCalculatedDelays);
        } 
 
        int GetNextDelay()
        { 
            int delay = 0;

            if ((this.preCalculatedDelays == null) || (this.preCalculatedDelays.Length == 0))
            { 
                delay = (int)(this.maxRandomDelayInMillis * this.random.NextDouble());
            } 
            else 
            {
                if (this.preCalculatedDelays.Length == 1 || this.currentDelayIndex == 0) 
                {
                    delay = this.preCalculatedDelays[0];
                }
                else 
                {
                    this.currentDelayIndex++; 
                    if (currentDelayIndex == this.preCalculatedDelays.Length) 
                    {
                        this.currentDelayIndex = 1; 
                    }

                    delay = this.preCalculatedDelays[this.currentDelayIndex] -
                        this.preCalculatedDelays[this.currentDelayIndex - 1]; 
                }
            } 
 
            return delay;
        } 

        class DelayAsyncResult : AsyncResult
        {
            readonly IOThreadTimer delayTimer; 
            static Action