QueryTask.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 / QueryTask.cs / 1305376 / QueryTask.cs
                        

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

using System.Threading; 
using System.Threading.Tasks;
using System.Diagnostics.Contracts; 
 
namespace System.Linq.Parallel
{ 
    // To disable exception marshaling (e.g. for debugging purposes), uncomment this symbol
    // or recompile PLINQ passing the symbol on the cmd-line, i.e. csc.exe ... /d:LET_...
    //#define LET_ASYNC_EXCEPTIONS_CRASH
 
    /// 
    /// Simple abstract task representation, allowing either synchronous and asynchronous 
    /// execution. Subclasses override the Work API to implement the logic. 
    /// 
    internal abstract class QueryTask 
    {

        protected int m_taskIndex; // The unique id of this task.
        protected QueryTaskGroupState m_groupState; // State shared among the tasks. 

        //------------------------------------------------------------------------------------ 
        // Constructs a new task with the specified shared state. 
        //
 
        protected QueryTask(int taskIndex, QueryTaskGroupState groupState)
        {
            Contract.Assert(groupState != null);
            m_taskIndex = taskIndex; 
            m_groupState = groupState;
        } 
 
        //-----------------------------------------------------------------------------------
        // A static function used by s_runTaskSynchronouslyDelegate, which is used by RunSynchronously 
        //

        private static void RunTaskSynchronously(object o)
        { 
            ((QueryTask)o).BaseWork(null);
        } 
 
        //-----------------------------------------------------------------------------------
        // A static delegate used by RunSynchronously 
        //

        private static Action s_runTaskSynchronouslyDelegate = RunTaskSynchronously;
 
        //-----------------------------------------------------------------------------------
        // Executes the task synchronously (on the current thread). 
        // 

        internal Task RunSynchronously(TaskScheduler taskScheduler) 
        {
            Contract.Assert(taskScheduler == TaskScheduler.Default, "PLINQ queries can currently execute only on the default scheduler.");
            TraceHelpers.TraceInfo("[timing]: {0}: Running work synchronously", DateTime.Now.Ticks, m_taskIndex);
            Task task = new Task(s_runTaskSynchronouslyDelegate, this, TaskCreationOptions.AttachedToParent); 
            task.RunSynchronously(taskScheduler);
            return task; 
        } 

        //------------------------------------------------------------------------------------ 
        // Executes the task asynchronously (elsewhere, unspecified).
        //

        private static Action s_baseWorkDelegate = delegate(object o) 
        {
            ((QueryTask)o).BaseWork(null); 
        }; 

        internal Task RunAsynchronously(TaskScheduler taskScheduler) 
        {
            Contract.Assert(taskScheduler == TaskScheduler.Default, "PLINQ queries can currently execute only on the default scheduler.");

            TraceHelpers.TraceInfo("[timing]: {0}: Queue work {1} to occur asynchronously", DateTime.Now.Ticks, m_taskIndex); 
            return Task.Factory.StartNew(s_baseWorkDelegate, this, new CancellationToken(), TaskCreationOptions.AttachedToParent | TaskCreationOptions.PreferFairness, taskScheduler);
        } 
 
        //-----------------------------------------------------------------------------------
        // Common function called regardless of [....] or async execution.  Just wraps some 
        // amount of tracing around the call to the real work API.
        //

        private void BaseWork(object unused) 
        {
            Contract.Assert(unused == null); 
            TraceHelpers.TraceInfo("[timing]: {0}: Start work {1}", DateTime.Now.Ticks, m_taskIndex); 

#if !FEATURE_PAL    // PAL doesn't support  eventing 
            PlinqEtwProvider.Log.ParallelQueryFork(m_groupState.QueryId);
#endif

            try 
            {
                Work(); 
            } 
            finally
            { 

#if !FEATURE_PAL    // PAL doesn't support  eventing
                PlinqEtwProvider.Log.ParallelQueryJoin(m_groupState.QueryId);
#endif 

            } 
 
            TraceHelpers.TraceInfo("[timing]: {0}: End work {1}", DateTime.Now.Ticks, m_taskIndex);
        } 

        //------------------------------------------------------------------------------------
        // API that subclasses override to provide task-specific logic.
        // 

        protected abstract void Work(); 
 
    }
} 

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

                        

                        
                        
                    
                    

                        
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