DefaultAsyncDataDispatcher.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / MS / Internal / Data / DefaultAsyncDataDispatcher.cs / 1 / DefaultAsyncDataDispatcher.cs
                        

                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// Description: Default async scheduler for data operations. 
// 
//---------------------------------------------------------------------------
 
using System;
using System.Collections;
using System.Threading;
using System.Windows; 
using System.Windows.Data;
using MS.Internal; 
 
namespace MS.Internal.Data
{ 
    internal class DefaultAsyncDataDispatcher : IAsyncDataDispatcher
    {
        //-----------------------------------------------------
        // 
        //  Interface: IAsyncDataDispatcher
        // 
        //----------------------------------------------------- 

        ///  Add a request to the dispatcher's queue  
        void IAsyncDataDispatcher.AddRequest(AsyncDataRequest request)
        {
            lock (_list.SyncRoot)
            { 
                _list.Add(request);
            } 
 
            ThreadPool.QueueUserWorkItem(new WaitCallback(ProcessRequest), request);
        } 

        ///  Cancel all requests in the dispatcher's queue 
        void IAsyncDataDispatcher.CancelAllRequests()
        { 
            lock (_list.SyncRoot)
            { 
                for (int i=0; i<_list.Count; ++i) 
                {
                    AsyncDataRequest request = (AsyncDataRequest)_list[i]; 
                    request.Cancel();
                }

                _list.Clear(); 
            }
        } 
 
        //------------------------------------------------------
        // 
        //  Private methods
        //
        //-----------------------------------------------------
 
        // Run a single request.  This method gets scheduled on a worker thread
        // from the process ThreadPool. 
        void ProcessRequest(object o) 
        {
            AsyncDataRequest request = (AsyncDataRequest)o; 

            // PreSharp uses message numbers that the C# compiler doesn't know about.
            // Disable the C# complaints, per the PreSharp documentation.
            #pragma warning disable 1634, 1691 

            // PreSharp complains about catching NullReference (and other) exceptions. 
            // In this case, these are precisely the ones we want to catch the most, 
            // so that a failure on a worker thread doesn't affect the main thread.
            #pragma warning disable 56500 

            // run the request - this may take a while
            try
            { 
                request.Complete(request.DoWork());
            } 
 
            // Catch all exceptions.  There is no app code on the stack,
            // so the exception isn't actionable by the app. 
            // Yet we don't want to crash the app.
            catch (Exception ex)
            {
                if (CriticalExceptions.IsCriticalException(ex)) 
                    throw;
 
                request.Fail(ex); 
            }
            catch // non CLS compliant exception 
            {
                request.Fail(new InvalidOperationException(SR.Get(SRID.NonCLSException, "processing an async data request")));
            }
 
            #pragma warning restore 56500
            #pragma warning restore 1634, 1691 
 
            // remove the request from the list
            lock (_list.SyncRoot) 
            {
                _list.Remove(request);
            }
        } 

        //------------------------------------------------------ 
        // 
        //  Private data
        // 
        //------------------------------------------------------

        ArrayList _list = new ArrayList();
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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