TaskCompletionSource<TResult> TaskCompletionSource<TResult> TaskCompletionSource<TResult> TaskCompletionSource<TResult> Class

Définition

Représente le côté producteur d'un Task<TResult> indépendant d'un délégué, en fournissant l'accès au côté consommateur via la propriété Task.Represents the producer side of a Task<TResult> unbound to a delegate, providing access to the consumer side through the Task property.

generic <typename TResult>
public ref class TaskCompletionSource
public class TaskCompletionSource<TResult>
type TaskCompletionSource<'Result> = class
Public Class TaskCompletionSource(Of TResult)

Paramètres de type

TResult

Type de la valeur de résultat associée à ce TaskCompletionSource<TResult>.The type of the result value associated with this TaskCompletionSource<TResult>.

Héritage
TaskCompletionSource<TResult>TaskCompletionSource<TResult>TaskCompletionSource<TResult>TaskCompletionSource<TResult>

Exemples

L’exemple suivant montre comment utiliser un TaskCompletionSource<TResult>:The following example shows how to use a TaskCompletionSource<TResult>:

using System;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;

class TCSDemo
{
    // Demonstrated features:
    // 		TaskCompletionSource ctor()
    // 		TaskCompletionSource.SetResult()
    // 		TaskCompletionSource.SetException()
    //		Task.Result
    // Expected results:
    // 		The attempt to get t1.Result blocks for ~1000ms until tcs1 gets signaled. 15 is printed out.
    // 		The attempt to get t2.Result blocks for ~1000ms until tcs2 gets signaled. An exception is printed out.
    static void Main()
    {
        TaskCompletionSource<int> tcs1 = new TaskCompletionSource<int>();
        Task<int> t1 = tcs1.Task;

        // Start a background task that will complete tcs1.Task
        Task.Factory.StartNew(() =>
        {
            Thread.Sleep(1000);
            tcs1.SetResult(15);
        });

        // The attempt to get the result of t1 blocks the current thread until the completion source gets signaled.
        // It should be a wait of ~1000 ms.
        Stopwatch sw = Stopwatch.StartNew();
        int result = t1.Result;
        sw.Stop();

        Console.WriteLine("(ElapsedTime={0}): t1.Result={1} (expected 15) ", sw.ElapsedMilliseconds, result);

        // ------------------------------------------------------------------

        // Alternatively, an exception can be manually set on a TaskCompletionSource.Task
        TaskCompletionSource<int> tcs2 = new TaskCompletionSource<int>();
        Task<int> t2 = tcs2.Task;

        // Start a background Task that will complete tcs2.Task with an exception
        Task.Factory.StartNew(() =>
        {
            Thread.Sleep(1000);
            tcs2.SetException(new InvalidOperationException("SIMULATED EXCEPTION"));
        });

        // The attempt to get the result of t2 blocks the current thread until the completion source gets signaled with either a result or an exception.
        // In either case it should be a wait of ~1000 ms.
        sw = Stopwatch.StartNew();
        try
        {
            result = t2.Result;

            Console.WriteLine("t2.Result succeeded. THIS WAS NOT EXPECTED.");
        }
        catch (AggregateException e)
        {
            Console.Write("(ElapsedTime={0}): ", sw.ElapsedMilliseconds);
            Console.WriteLine("The following exceptions have been thrown by t2.Result: (THIS WAS EXPECTED)");
            for (int j = 0; j < e.InnerExceptions.Count; j++)
            {
                Console.WriteLine("\n-------------------------------------------------\n{0}", e.InnerExceptions[j].ToString());
            }
        }
    }

}
Imports System.Diagnostics
Imports System.Threading
Imports System.Threading.Tasks

Module TCSDemo
    ' Demonstrated features:
    '   TaskCompletionSource ctor()
    '   TaskCompletionSource.SetResult()
    '   TaskCompletionSource.SetException()
    '   Task.Result
    ' Expected results:
    '   The attempt to get t1.Result blocks for ~1000ms until tcs1 gets signaled. 15 is printed out.
    '   The attempt to get t2.Result blocks for ~1000ms until tcs2 gets signaled. An exception is printed out.

    Private Sub Main()
        Dim tcs1 As New TaskCompletionSource(Of Integer)()
        Dim t1 As Task(Of Integer) = tcs1.Task

        ' Start a background task that will complete tcs1.Task
        Task.Factory.StartNew(Sub()
                                  Thread.Sleep(1000)
                                  tcs1.SetResult(15)
                              End Sub)

        ' The attempt to get the result of t1 blocks the current thread until the completion source gets signaled.
        ' It should be a wait of ~1000 ms.
        Dim sw As Stopwatch = Stopwatch.StartNew()
        Dim result As Integer = t1.Result
        sw.Stop()

        Console.WriteLine("(ElapsedTime={0}): t1.Result={1} (expected 15) ", sw.ElapsedMilliseconds, result)

        ' ------------------------------------------------------------------

        ' Alternatively, an exception can be manually set on a TaskCompletionSource.Task
        Dim tcs2 As New TaskCompletionSource(Of Integer)()
        Dim t2 As Task(Of Integer) = tcs2.Task

        ' Start a background Task that will complete tcs2.Task with an exception
        Task.Factory.StartNew(Sub()
                                  Thread.Sleep(1000)
                                  tcs2.SetException(New InvalidOperationException("SIMULATED EXCEPTION"))
                              End Sub)

        ' The attempt to get the result of t2 blocks the current thread until the completion source gets signaled with either a result or an exception.
        ' In either case it should be a wait of ~1000 ms.
        sw = Stopwatch.StartNew()
        Try
            result = t2.Result

            Console.WriteLine("t2.Result succeeded. THIS WAS NOT EXPECTED.")
        Catch e As AggregateException
            Console.Write("(ElapsedTime={0}): ", sw.ElapsedMilliseconds)
            Console.WriteLine("The following exceptions have been thrown by t2.Result: (THIS WAS EXPECTED)")
            For j As Integer = 0 To e.InnerExceptions.Count - 1
                Console.WriteLine(vbLf & "-------------------------------------------------" & vbLf & "{0}", e.InnerExceptions(j).ToString())
            Next
        End Try
    End Sub

End Module

Remarques

Dans de nombreux scénarios, il est utile d’activer Task<TResult> un pour représenter une opération asynchrone externe.In many scenarios, it is useful to enable a Task<TResult> to represent an external asynchronous operation. TaskCompletionSource<TResult>est fourni à cet effet.TaskCompletionSource<TResult> is provided for this purpose. Il permet de créer une tâche qui peut être transremise aux consommateurs.It enables the creation of a task that can be handed out to consumers. Les consommateurs peuvent utiliser les membres de la tâche de la même façon que dans tout autre scénario de traitement des variables de membre de tâche.The consumers can use the members of the task the same way as they would in any other scenario handling task member variables. Toutefois, contrairement à la plupart des tâches, l’état d’une tâche créée par un TaskCompletionSource est contrôlé explicitement par les méthodes sur TaskCompletionSource.However, unlike most tasks, the state of a task created by a TaskCompletionSource is controlled explicitly by the methods on TaskCompletionSource. Cela permet à l’achèvement de l’opération asynchrone externe de se propager à la tâche sous-jacente.This enables the completion of the external asynchronous operation to be propagated to the underlying Task. La séparation garantit également que les consommateurs ne sont pas en mesure de faire passer l’État sans accéder aux TaskCompletionSource correspondants.The separation also ensures that consumers are not able to transition the state without access to the corresponding TaskCompletionSource. Pour plus d’informations, consultez l’entrée de la nature<de TaskCompletionSource TResult > dans le blog Parallel Programming with .net (en anglais).For more information, see the entry The Nature of TaskCompletionSource<TResult> in the Parallel Programming with .NET blog.

Les exemples Parallel Extensions contiennent également des exemples d’utilisation TaskCompletionSource<TResult>de.The Parallel Extensions samples also contain examples of how to use TaskCompletionSource<TResult>.

Constructeurs

TaskCompletionSource<TResult>() TaskCompletionSource<TResult>() TaskCompletionSource<TResult>() TaskCompletionSource<TResult>()

Crée un TaskCompletionSource<TResult>.Creates a TaskCompletionSource<TResult>.

TaskCompletionSource<TResult>(Object) TaskCompletionSource<TResult>(Object) TaskCompletionSource<TResult>(Object) TaskCompletionSource<TResult>(Object)

Crée un TaskCompletionSource<TResult> avec l'état spécifié.Creates a TaskCompletionSource<TResult> with the specified state.

TaskCompletionSource<TResult>(Object, TaskCreationOptions) TaskCompletionSource<TResult>(Object, TaskCreationOptions) TaskCompletionSource<TResult>(Object, TaskCreationOptions) TaskCompletionSource<TResult>(Object, TaskCreationOptions)

Crée un TaskCompletionSource<TResult> avec l'état et les options spécifiés.Creates a TaskCompletionSource<TResult> with the specified state and options.

TaskCompletionSource<TResult>(TaskCreationOptions) TaskCompletionSource<TResult>(TaskCreationOptions) TaskCompletionSource<TResult>(TaskCreationOptions) TaskCompletionSource<TResult>(TaskCreationOptions)

Crée un TaskCompletionSource<TResult> avec les options spécifiées.Creates a TaskCompletionSource<TResult> with the specified options.

Propriétés

Task Task Task Task

Obtient le Task<TResult> créé par ce TaskCompletionSource<TResult>.Gets the Task<TResult> created by this TaskCompletionSource<TResult>.

Méthodes

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Détermine si l'objet spécifié est identique à l'objet actuel.Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Fait office de fonction de hachage par défaut.Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

Obtient le Type de l'instance actuelle.Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Crée une copie superficielle de l'objet Object actuel.Creates a shallow copy of the current Object.

(Inherited from Object)
SetCanceled() SetCanceled() SetCanceled() SetCanceled()

Fait passer le Task<TResult> sous-jacent à l'état Canceled.Transitions the underlying Task<TResult> into the Canceled state.

SetException(Exception) SetException(Exception) SetException(Exception) SetException(Exception)

Transfère le Task<TResult> sous-jacent en état Faulted et le lie à une exception spécifiée.Transitions the underlying Task<TResult> into the Faulted state and binds it to a specified exception.

SetException(IEnumerable<Exception>) SetException(IEnumerable<Exception>) SetException(IEnumerable<Exception>) SetException(IEnumerable<Exception>)

Transfère le Task<TResult> sous-jacent en état Faulted et lui associe une collection d’objets d’exception.Transitions the underlying Task<TResult> into the Faulted state and binds a collection of exception objects to it.

SetResult(TResult) SetResult(TResult) SetResult(TResult) SetResult(TResult)

Fait passer le Task<TResult> sous-jacent à l'état RanToCompletion.Transitions the underlying Task<TResult> into the RanToCompletion state.

ToString() ToString() ToString() ToString()

Retourne une chaîne qui représente l'objet actuel.Returns a string that represents the current object.

(Inherited from Object)
TrySetCanceled() TrySetCanceled() TrySetCanceled() TrySetCanceled()

Tente de faire passer le Task<TResult> sous-jacent à l'état Canceled.Attempts to transition the underlying Task<TResult> into the Canceled state.

TrySetCanceled(CancellationToken) TrySetCanceled(CancellationToken) TrySetCanceled(CancellationToken) TrySetCanceled(CancellationToken)

Tente de faire passer le Task<TResult> sous-jacent à l'état Canceled et permet le stockage d'un jeton d'annulation dans la tâche annulée.Attempts to transition the underlying Task<TResult> into the Canceled state and enables a cancellation token to be stored in the canceled task.

TrySetException(Exception) TrySetException(Exception) TrySetException(Exception) TrySetException(Exception)

Tente de faire passer le Task<TResult> sous-jacent en état Faulted et le lie à une exception spécifiée.Attempts to transition the underlying Task<TResult> into the Faulted state and binds it to a specified exception.

TrySetException(IEnumerable<Exception>) TrySetException(IEnumerable<Exception>) TrySetException(IEnumerable<Exception>) TrySetException(IEnumerable<Exception>)

Tente de faire passer le Task<TResult> sous-jacent en état Faulted et lui associe une collection d’objets d’exception.Attempts to transition the underlying Task<TResult> into the Faulted state and binds a collection of exception objects to it.

TrySetResult(TResult) TrySetResult(TResult) TrySetResult(TResult) TrySetResult(TResult)

Tente de faire passer le Task<TResult> sous-jacent à l'état RanToCompletion.Attempts to transition the underlying Task<TResult> into the RanToCompletion state.

S’applique à

Cohérence de thread

Tous les membres TaskCompletionSource<TResult> de sont thread-safe et peuvent être utilisés simultanément à partir de plusieurs threads.All members of TaskCompletionSource<TResult> are thread-safe and may be used from multiple threads concurrently.

Voir aussi