OverlappedAsyncResult.cs source code in C# .NET

                        Code:
                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / WCF / Log / System / IO / Log / OverlappedAsyncResult.cs / 1 / OverlappedAsyncResult.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------
namespace System.IO.Log
{ 
    using System;
    using System.Diagnostics; 
    using System.Runtime.InteropServices; 
    using System.Security.Permissions;
    using System.Threading; 
    using System.ServiceModel.Diagnostics;

    using Microsoft.Win32.SafeHandles;
 
    // How to use:
    //   1. Subclass, implement IOCompleted. 
    //   2. Call Pack() each time before invoking native method. 
    //   3. Use NativeOverlapped pointer in native method
    //   4. If call completes synchronously, Free() immediately 
    //   5. If call completes asynchronously, Free() is called for you
    //
    unsafe abstract class OverlappedAsyncResult : IAsyncResult
    { 
        // Boring stuff needed to implement IAsyncResult
        // correctly. 
        // 
        object userState;
        AsyncCallback callback; 

        ManualResetEvent waitHandle;
        object syncRoot;
 
        bool isCompleted;
        bool completedSynchronously; 
        bool endCalled; 

        Exception storedException; 

        // More exciting stuff...
        //
        NativeOverlapped* nativeOverlapped; 

        protected OverlappedAsyncResult(AsyncCallback callback, 
                                        object state) 
        {
            this.callback = callback; 
            this.userState = state;
            this.syncRoot = new Object();

            GC.SuppressFinalize(this); 
        }
 
        ~OverlappedAsyncResult() 
        {
            // Avoid leaking the NativeOverlapped in case things go wrong 
            if (!Environment.HasShutdownStarted &&
                !AppDomain.CurrentDomain.IsFinalizingForUnload())
            {
                Free(); 
            }
        } 
 
        public Object AsyncState
        { 
            get { return this.userState; }
        }

        public WaitHandle AsyncWaitHandle 
        {
            get 
            { 
                lock (this.syncRoot)
                { 
                    if (this.waitHandle == null)
                    {
                        this.waitHandle = new ManualResetEvent(this.isCompleted);
                    } 
                }
 
                return this.waitHandle; 
            }
        } 

        public bool CompletedSynchronously
        {
            get { return this.completedSynchronously; } 
        }
 
        public bool IsCompleted 
        {
            get { return this.isCompleted; } 
        }

        internal NativeOverlapped *NativeOverlapped
        { 
            get { return this.nativeOverlapped; }
        } 
 
        internal void Complete(bool completedSynchronously, Exception exception)
        { 
            lock (this.syncRoot)
            {
                this.storedException = exception;
                this.completedSynchronously = completedSynchronously; 
                this.isCompleted = true;
 
                if (this.waitHandle != null) 
                    this.waitHandle.Set();
 
                Monitor.PulseAll(this.syncRoot);
            }

            if (this.callback != null) 
            {
                if (!completedSynchronously || 
                    !ThreadPool.QueueUserWorkItem(InvokeUserCallback, this)) 
                {
                    InvokeUserCallbackFunction(this); 
                }
            }
        }
 
        public void End()
        { 
            lock (this.syncRoot) 
            {
                while (!this.IsCompleted) 
                {
                    Monitor.Wait(this.syncRoot);
                }
 
                if (this.endCalled)
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.DuplicateEnd()); 
                this.endCalled = true; 

                if (this.storedException != null) 
                {
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(this.storedException);
                }
           } 
        }
 
        internal void Free() 
        {
            if (this.nativeOverlapped != null) 
            {
                GC.SuppressFinalize(this);
                Overlapped.Free(this.nativeOverlapped);
                this.nativeOverlapped = null; 
            }
        } 
 
        internal void Pack(object pinnedObjects)
        { 
            if (this.nativeOverlapped != null)
            {
                // If we reach this condition, we have a bug in a derived AsyncResult class.
                // It attempted to initiate a new async I/O operation before the previous 
                // one completed. This is a fatal condition, so we cannot continue execution.
                DiagnosticUtility.FailFast("Must allow previous I/O to complete before packing"); 
            } 

            GC.ReRegisterForFinalize(this); 

            Overlapped overlapped = new Overlapped(0, 0, IntPtr.Zero, this);
            if (this.callback == null)
            { 
                this.nativeOverlapped = overlapped.UnsafePack(
                    IOCompletionCallback, 
                    pinnedObjects); 
            }
            else 
            {
                this.nativeOverlapped = overlapped.Pack(
                    IOCompletionCallback,
                    pinnedObjects); 
            }
        } 
 
        internal abstract void IOCompleted(uint errorCode);
 
        static IOCompletionCallback IOCompletionCallback = DiagnosticUtility.Utility.ThunkCallback(new IOCompletionCallback(CompletionCallback));

        static void CompletionCallback(
            uint errorCode, 
            uint numBytes,
            NativeOverlapped* nativeOverlapped) 
        { 
            try
            { 
                Overlapped overlapped = Overlapped.Unpack(nativeOverlapped);

                OverlappedAsyncResult result;
                result = (OverlappedAsyncResult)overlapped.AsyncResult; 
                result.Free();
 
                result.IOCompleted(errorCode); 
            }
#pragma warning suppress 56500 // We will be terminating the process with any exception in this call 
            catch(Exception e)
            {
                // The code in the try block should not throw any exceptions.
                // If an exception is caught here, IO.Log may be in an unknown state. 
                // We prefer to failfast instead of risking the possibility of log corruption.
                // Any client code using IO.Log must have a recovery model that can deal 
                // with appdomain and process failures. 
                DiagnosticUtility.InvokeFinalHandler(e);
            } 
        }

        static WaitCallback InvokeUserCallback = DiagnosticUtility.Utility.ThunkCallback(new WaitCallback(InvokeUserCallbackFunction));
 
        static void InvokeUserCallbackFunction(
            object data) 
        { 
            try
            { 
                OverlappedAsyncResult result = (OverlappedAsyncResult)data;
                result.callback(result);
            }
#pragma warning suppress 56500 // We will be terminating the process with any exception in this call 
            catch(Exception e)
            { 
                if (DiagnosticUtility.IsFatal(e)) 
                    throw;
 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperCallback(e);
            }
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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OverlappedAsyncResult.cs source code in C# .NET

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