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Útmutató: Feladatütemező megadása adatfolyamblokkban

Ez a dokumentum bemutatja, hogyan társíthat egy adott feladatütemezőt, amikor adatfolyamot használ az alkalmazásban. A példa egy System.Threading.Tasks.ConcurrentExclusiveSchedulerPair Windows Forms-alkalmazás osztályával jeleníti meg, hogy mikor aktívak az olvasói feladatok, és mikor aktív egy írói tevékenység. Azt is használja a TaskScheduler.FromCurrentSynchronizationContext metódust, hogy engedélyezze az adatfolyam-blokkok futtatását a felhasználói felület szálán.

Feljegyzés

A TPL-adatfolyamtár (a System.Threading.Tasks.Dataflow névtér) nincs elosztva a .NET-tel. Ha telepíteni szeretné a névteret a System.Threading.Tasks.Dataflow Visual Studióban, nyissa meg a projektet, válassza a Project menü NuGet-csomagok kezelése parancsát, és keressen rá online a System.Threading.Tasks.Dataflow csomagra. Másik lehetőségként futtassa dotnet add package System.Threading.Tasks.Dataflowa .NET Core parancssori felülettel való telepítéshez.

A Windows Forms alkalmazás létrehozása

  1. Visual C# vagy Visual Basic Windows Forms-alkalmazásprojekt létrehozása. A következő lépésekben a projekt neve .WriterReadersWinForms

  2. A főűrlap űrlaptervezőjében Form1.cs (Form1.vb Visual Basichez) adjon hozzá négy CheckBox vezérlőt. Állítsa be a tulajdonságot a Text Következőhöz: Reader 1 for checkBox1, Reader 2 for checkBox2, Reader 3 for checkBox3, and Writer for checkBox4. Állítsa be az Enabled egyes vezérlők tulajdonságát a következőre False: .

  3. Timer Vezérlőelem hozzáadása az űrlaphoz. Állítsa be a tulajdonságot a Interval következőre 2500: .

Adatfolyam-funkciók hozzáadása

Ez a szakasz bemutatja, hogyan hozhatók létre az alkalmazásban részt vevő adatfolyamblokkok, és hogyan társíthatók mindegyiket egy feladatütemezőhöz.

Adatfolyam-funkciók hozzáadása az alkalmazáshoz

  1. A projektben adjon hozzá egy hivatkozást a System.Threading.Tasks.Dataflow.dll.

  2. Győződjön meg arról, hogy a Form1.cs (a Visual Basic Form1.vb) tartalmazza a következő using irányelveket (Imports a Visual Basicben).

    using System;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using System.Threading.Tasks.Dataflow;
using System.Windows.Forms;

    Imports System.Threading
Imports System.Threading.Tasks
Imports System.Threading.Tasks.Dataflow

  3. Adjon hozzá egy BroadcastBlock<T> adattagot az Form1 osztályhoz.

    // Broadcasts values to an ActionBlock<int> object that is associated
// with each check box.
BroadcastBlock<int> broadcaster = new BroadcastBlock<int>(null);

    ' Broadcasts values to an ActionBlock<int> object that is associated
' with each check box.
Private broadcaster As New BroadcastBlock(Of Integer)(Nothing)

  4. A konstruktorban a Form1 hívás InitializeComponentután hozzon létre egy ActionBlock<TInput> objektumot, amely az objektumok állapotát CheckBox váltja ki.

    // Create an ActionBlock<CheckBox> object that toggles the state
// of CheckBox objects.
// Specifying the current synchronization context enables the
// action to run on the user-interface thread.
var toggleCheckBox = new ActionBlock<CheckBox>(checkBox =>
{
   checkBox.Checked = !checkBox.Checked;
},
new ExecutionDataflowBlockOptions
{
   TaskScheduler = TaskScheduler.FromCurrentSynchronizationContext()
});

    ' Create an ActionBlock<CheckBox> object that toggles the state
' of CheckBox objects.
' Specifying the current synchronization context enables the 
' action to run on the user-interface thread.
Dim toggleCheckBox = New ActionBlock(Of CheckBox)(Sub(checkBox) checkBox.Checked = Not checkBox.Checked, New ExecutionDataflowBlockOptions With {.TaskScheduler = TaskScheduler.FromCurrentSynchronizationContext()})

  5. A konstruktorban Form1 hozzon létre egy ConcurrentExclusiveSchedulerPair objektumot és négy ActionBlock<TInput> objektumot, minden objektumhoz CheckBox egy ActionBlock<TInput> objektumot. Minden ActionBlock<TInput> objektumhoz adjon meg egy ExecutionDataflowBlockOptions objektumot, amelynek TaskScheduler tulajdonsága az ConcurrentScheduler olvasók tulajdonsága, és az ExclusiveScheduler író tulajdonsága.

    // Create a ConcurrentExclusiveSchedulerPair object.
// Readers will run on the concurrent part of the scheduler pair.
// The writer will run on the exclusive part of the scheduler pair.
var taskSchedulerPair = new ConcurrentExclusiveSchedulerPair();

// Create an ActionBlock<int> object for each reader CheckBox object.
// Each ActionBlock<int> object represents an action that can read
// from a resource in parallel to other readers.
// Specifying the concurrent part of the scheduler pair enables the
// reader to run in parallel to other actions that are managed by
// that scheduler.
var readerActions =
   from checkBox in new CheckBox[] {checkBox1, checkBox2, checkBox3}
   select new ActionBlock<int>(milliseconds =>
   {
      // Toggle the check box to the checked state.
      toggleCheckBox.Post(checkBox);

      // Perform the read action. For demonstration, suspend the current
      // thread to simulate a lengthy read operation.
      Thread.Sleep(milliseconds);

      // Toggle the check box to the unchecked state.
      toggleCheckBox.Post(checkBox);
   },
   new ExecutionDataflowBlockOptions
   {
      TaskScheduler = taskSchedulerPair.ConcurrentScheduler
   });

// Create an ActionBlock<int> object for the writer CheckBox object.
// This ActionBlock<int> object represents an action that writes to
// a resource, but cannot run in parallel to readers.
// Specifying the exclusive part of the scheduler pair enables the
// writer to run in exclusively with respect to other actions that are
// managed by the scheduler pair.
var writerAction = new ActionBlock<int>(milliseconds =>
{
   // Toggle the check box to the checked state.
   toggleCheckBox.Post(checkBox4);

   // Perform the write action. For demonstration, suspend the current
   // thread to simulate a lengthy write operation.
   Thread.Sleep(milliseconds);

   // Toggle the check box to the unchecked state.
   toggleCheckBox.Post(checkBox4);
},
new ExecutionDataflowBlockOptions
{
   TaskScheduler = taskSchedulerPair.ExclusiveScheduler
});

// Link the broadcaster to each reader and writer block.
// The BroadcastBlock<T> class propagates values that it
// receives to all connected targets.
foreach (var readerAction in readerActions)
{
   broadcaster.LinkTo(readerAction);
}
broadcaster.LinkTo(writerAction);

    ' Create a ConcurrentExclusiveSchedulerPair object.
' Readers will run on the concurrent part of the scheduler pair.
' The writer will run on the exclusive part of the scheduler pair.
Dim taskSchedulerPair = New ConcurrentExclusiveSchedulerPair()

' Create an ActionBlock<int> object for each reader CheckBox object.
' Each ActionBlock<int> object represents an action that can read 
' from a resource in parallel to other readers.
' Specifying the concurrent part of the scheduler pair enables the 
' reader to run in parallel to other actions that are managed by 
' that scheduler.
Dim readerActions = From checkBox In New CheckBox() {checkBox1, checkBox2, checkBox3} _
                    Select New ActionBlock(Of Integer)(Sub(milliseconds)
                                           ' Toggle the check box to the checked state.
                                           ' Perform the read action. For demonstration, suspend the current
                                           ' thread to simulate a lengthy read operation.
                                           ' Toggle the check box to the unchecked state.
                                           toggleCheckBox.Post(checkBox)
                                                           Thread.Sleep(milliseconds)
                                                           toggleCheckBox.Post(checkBox)
                                                       End Sub, New ExecutionDataflowBlockOptions With {.TaskScheduler = taskSchedulerPair.ConcurrentScheduler})

' Create an ActionBlock<int> object for the writer CheckBox object.
' This ActionBlock<int> object represents an action that writes to 
' a resource, but cannot run in parallel to readers.
' Specifying the exclusive part of the scheduler pair enables the 
' writer to run in exclusively with respect to other actions that are 
' managed by the scheduler pair.
Dim writerAction = New ActionBlock(Of Integer)(Sub(milliseconds)
                                                   ' Toggle the check box to the checked state.
                                                   ' Perform the write action. For demonstration, suspend the current
                                                   ' thread to simulate a lengthy write operation.
                                                   ' Toggle the check box to the unchecked state.
                                                   toggleCheckBox.Post(checkBox4)
                                                   Thread.Sleep(milliseconds)
                                                   toggleCheckBox.Post(checkBox4)
                                               End Sub, New ExecutionDataflowBlockOptions With {.TaskScheduler = taskSchedulerPair.ExclusiveScheduler})

' Link the broadcaster to each reader and writer block.
' The BroadcastBlock<T> class propagates values that it 
' receives to all connected targets.
For Each readerAction In readerActions
    broadcaster.LinkTo(readerAction)
Next readerAction
broadcaster.LinkTo(writerAction)

  6. Form1 A konstruktorban indítsa el az Timer objektumot.

    // Start the timer.
timer1.Start();

    ' Start the timer.
timer1.Start()

  7. A főűrlap űrlaptervezőjében hozzon létre egy eseménykezelőt az Tick eseményhez az időzítőhöz.

  8. Implementálja az Tick eseményt az időzítőhöz.

    // Event handler for the timer.
private void timer1_Tick(object sender, EventArgs e)
{
   // Post a value to the broadcaster. The broadcaster
   // sends this message to each target.
   broadcaster.Post(1000);
}

    ' Event handler for the timer.
Private Sub timer1_Tick(ByVal sender As Object, ByVal e As EventArgs) Handles timer1.Tick
    ' Post a value to the broadcaster. The broadcaster
    ' sends this message to each target. 
    broadcaster.Post(1000)
End Sub

Mivel az toggleCheckBox adatfolyam-blokk a felhasználói felületen működik, fontos, hogy ez a művelet a felhasználói felület szálán történjen. Ennek érdekében az építés során ez az objektum egy ExecutionDataflowBlockOptions objektumot biztosít, amelynek tulajdonsága TaskScheduler a következőre van állítva TaskScheduler.FromCurrentSynchronizationContext. A FromCurrentSynchronizationContext metódus létrehoz egy TaskScheduler objektumot, amely az aktuális szinkronizálási környezetben végez munkát. Mivel a Form1 konstruktor a felhasználói felületi szálból van meghívva, az toggleCheckBox adatfolyam-blokk művelete a felhasználói felület szálán is fut.

Ez a példa arra is használja az ConcurrentExclusiveSchedulerPair osztályt, hogy lehetővé tegye egyes adatfolyamblokkok egyidejű működést, egy másik adatfolyamblokk pedig kizárólagosan működjön az ugyanazon ConcurrentExclusiveSchedulerPair az objektumon futó összes többi adatfolyamblokk tekintetében. Ez a technika akkor hasznos, ha több adatfolyam-blokk osztozik egy erőforráson, és némelyikhez kizárólagos hozzáférésre van szükség, mivel ez szükségtelenné teszi az erőforráshoz való hozzáférés manuális szinkronizálását. A manuális szinkronizálás megszüntetése hatékonyabbá teheti a kódot.

Példa

Az alábbi példa a Form1.cs teljes kódját mutatja be (Form1.vb a Visual Basichez).

using System;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using System.Threading.Tasks.Dataflow;
using System.Windows.Forms;

namespace WriterReadersWinForms
{
   public partial class Form1 : Form
   {
      // Broadcasts values to an ActionBlock<int> object that is associated
      // with each check box.
      BroadcastBlock<int> broadcaster = new BroadcastBlock<int>(null);

      public Form1()
      {
         InitializeComponent();

         // Create an ActionBlock<CheckBox> object that toggles the state
         // of CheckBox objects.
         // Specifying the current synchronization context enables the
         // action to run on the user-interface thread.
         var toggleCheckBox = new ActionBlock<CheckBox>(checkBox =>
         {
            checkBox.Checked = !checkBox.Checked;
         },
         new ExecutionDataflowBlockOptions
         {
            TaskScheduler = TaskScheduler.FromCurrentSynchronizationContext()
         });

         // Create a ConcurrentExclusiveSchedulerPair object.
         // Readers will run on the concurrent part of the scheduler pair.
         // The writer will run on the exclusive part of the scheduler pair.
         var taskSchedulerPair = new ConcurrentExclusiveSchedulerPair();

         // Create an ActionBlock<int> object for each reader CheckBox object.
         // Each ActionBlock<int> object represents an action that can read
         // from a resource in parallel to other readers.
         // Specifying the concurrent part of the scheduler pair enables the
         // reader to run in parallel to other actions that are managed by
         // that scheduler.
         var readerActions =
            from checkBox in new CheckBox[] {checkBox1, checkBox2, checkBox3}
            select new ActionBlock<int>(milliseconds =>
            {
               // Toggle the check box to the checked state.
               toggleCheckBox.Post(checkBox);

               // Perform the read action. For demonstration, suspend the current
               // thread to simulate a lengthy read operation.
               Thread.Sleep(milliseconds);

               // Toggle the check box to the unchecked state.
               toggleCheckBox.Post(checkBox);
            },
            new ExecutionDataflowBlockOptions
            {
               TaskScheduler = taskSchedulerPair.ConcurrentScheduler
            });

         // Create an ActionBlock<int> object for the writer CheckBox object.
         // This ActionBlock<int> object represents an action that writes to
         // a resource, but cannot run in parallel to readers.
         // Specifying the exclusive part of the scheduler pair enables the
         // writer to run in exclusively with respect to other actions that are
         // managed by the scheduler pair.
         var writerAction = new ActionBlock<int>(milliseconds =>
         {
            // Toggle the check box to the checked state.
            toggleCheckBox.Post(checkBox4);

            // Perform the write action. For demonstration, suspend the current
            // thread to simulate a lengthy write operation.
            Thread.Sleep(milliseconds);

            // Toggle the check box to the unchecked state.
            toggleCheckBox.Post(checkBox4);
         },
         new ExecutionDataflowBlockOptions
         {
            TaskScheduler = taskSchedulerPair.ExclusiveScheduler
         });

         // Link the broadcaster to each reader and writer block.
         // The BroadcastBlock<T> class propagates values that it
         // receives to all connected targets.
         foreach (var readerAction in readerActions)
         {
            broadcaster.LinkTo(readerAction);
         }
         broadcaster.LinkTo(writerAction);

         // Start the timer.
         timer1.Start();
      }

      // Event handler for the timer.
      private void timer1_Tick(object sender, EventArgs e)
      {
         // Post a value to the broadcaster. The broadcaster
         // sends this message to each target.
         broadcaster.Post(1000);
      }
   }
}

Imports System.Threading
Imports System.Threading.Tasks
Imports System.Threading.Tasks.Dataflow


Namespace WriterReadersWinForms
    Partial Public Class Form1
        Inherits Form
        ' Broadcasts values to an ActionBlock<int> object that is associated
        ' with each check box.
        Private broadcaster As New BroadcastBlock(Of Integer)(Nothing)

        Public Sub New()
            InitializeComponent()

            ' Create an ActionBlock<CheckBox> object that toggles the state
            ' of CheckBox objects.
            ' Specifying the current synchronization context enables the 
            ' action to run on the user-interface thread.
            Dim toggleCheckBox = New ActionBlock(Of CheckBox)(Sub(checkBox) checkBox.Checked = Not checkBox.Checked, New ExecutionDataflowBlockOptions With {.TaskScheduler = TaskScheduler.FromCurrentSynchronizationContext()})

            ' Create a ConcurrentExclusiveSchedulerPair object.
            ' Readers will run on the concurrent part of the scheduler pair.
            ' The writer will run on the exclusive part of the scheduler pair.
            Dim taskSchedulerPair = New ConcurrentExclusiveSchedulerPair()

            ' Create an ActionBlock<int> object for each reader CheckBox object.
            ' Each ActionBlock<int> object represents an action that can read 
            ' from a resource in parallel to other readers.
            ' Specifying the concurrent part of the scheduler pair enables the 
            ' reader to run in parallel to other actions that are managed by 
            ' that scheduler.
            Dim readerActions = From checkBox In New CheckBox() {checkBox1, checkBox2, checkBox3} _
                                Select New ActionBlock(Of Integer)(Sub(milliseconds)
                                                       ' Toggle the check box to the checked state.
                                                       ' Perform the read action. For demonstration, suspend the current
                                                       ' thread to simulate a lengthy read operation.
                                                       ' Toggle the check box to the unchecked state.
                                                       toggleCheckBox.Post(checkBox)
                                                                       Thread.Sleep(milliseconds)
                                                                       toggleCheckBox.Post(checkBox)
                                                                   End Sub, New ExecutionDataflowBlockOptions With {.TaskScheduler = taskSchedulerPair.ConcurrentScheduler})

            ' Create an ActionBlock<int> object for the writer CheckBox object.
            ' This ActionBlock<int> object represents an action that writes to 
            ' a resource, but cannot run in parallel to readers.
            ' Specifying the exclusive part of the scheduler pair enables the 
            ' writer to run in exclusively with respect to other actions that are 
            ' managed by the scheduler pair.
            Dim writerAction = New ActionBlock(Of Integer)(Sub(milliseconds)
                                                               ' Toggle the check box to the checked state.
                                                               ' Perform the write action. For demonstration, suspend the current
                                                               ' thread to simulate a lengthy write operation.
                                                               ' Toggle the check box to the unchecked state.
                                                               toggleCheckBox.Post(checkBox4)
                                                               Thread.Sleep(milliseconds)
                                                               toggleCheckBox.Post(checkBox4)
                                                           End Sub, New ExecutionDataflowBlockOptions With {.TaskScheduler = taskSchedulerPair.ExclusiveScheduler})

            ' Link the broadcaster to each reader and writer block.
            ' The BroadcastBlock<T> class propagates values that it 
            ' receives to all connected targets.
            For Each readerAction In readerActions
                broadcaster.LinkTo(readerAction)
            Next readerAction
            broadcaster.LinkTo(writerAction)

            ' Start the timer.
            timer1.Start()
        End Sub

        ' Event handler for the timer.
        Private Sub timer1_Tick(ByVal sender As Object, ByVal e As EventArgs) Handles timer1.Tick
            ' Post a value to the broadcaster. The broadcaster
            ' sends this message to each target. 
            broadcaster.Post(1000)
        End Sub
    End Class
End Namespace

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