SpoolingTaskBase.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / Scheduling / SpoolingTaskBase.cs / 1305376 / SpoolingTaskBase.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
// 
// SpoolingTaskBase.cs 
//
// [....] 
//
// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

using System.Collections.Generic; 
using System.Threading;
using System.Diagnostics.Contracts; 
 
namespace System.Linq.Parallel
{ 
    /// 
    /// A spooling task handles marshaling data from a producer to a consumer. It simply
    /// takes data from a producer and hands it off to a consumer. This class is the base
    /// class from which other concrete spooling tasks derive, encapsulating some common 
    /// logic (such as capturing exceptions).
    ///  
    internal abstract class SpoolingTaskBase : QueryTask 
    {
        //------------------------------------------------------------------------------------ 
        // Constructs a new spooling task.
        //
        // Arguments:
        //     taskIndex   - the unique index of this task 
        //
 
        protected SpoolingTaskBase(int taskIndex, QueryTaskGroupState groupState) : 
            base(taskIndex, groupState)
        { 
        }

        //-----------------------------------------------------------------------------------
        // The implementation of the Work API just enumerates the producer's data, and 
        // enqueues it into the consumer channel. Well, really, it just defers to extension
        // points (below) implemented by subclasses to do these things. 
        // 

        protected override void Work() 
        {
            try
            {
                // Defer to the base class for the actual work. 
                SpoolingWork();
            } 
            catch (Exception ex) 
            {
                OperationCanceledException oce = ex as OperationCanceledException; 
                if (oce != null &&
                    oce.CancellationToken == m_groupState.CancellationState.MergedCancellationToken
                    && m_groupState.CancellationState.MergedCancellationToken.IsCancellationRequested)
                { 
                    //an expected internal cancellation has occurred.  suppress this exception.
                } 
                else 
                {
                    // TPL will catch and store the exception on the task object. We'll then later 
                    // turn around and wait on it, having the effect of propagating it. In the meantime,
                    // we want to cooperative cancel all workers.
                    m_groupState.CancellationState.InternalCancellationTokenSource.Cancel();
 
                    // And then repropagate to let TPL catch it.
                    throw; 
                } 
            }
            finally 
            {
                SpoolingFinally(); //dispose resources etc.
            }
        } 

        //----------------------------------------------------------------------------------- 
        // This method is responsible for enumerating results and enqueueing them to 
        // the output channel(s) as appropriate.  Each base class implements its own.
        // 

        protected abstract void SpoolingWork();

        //----------------------------------------------------------------------------------- 
        // If the subclass needs to do something in the finally block of the main work loop,
        // it should override this and do it.  Purely optional. 
        // 

        protected virtual void SpoolingFinally() 
        {
            // (Intentionally left blank.)
        }
 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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