TaskExtensions.Unwrap TaskExtensions.Unwrap TaskExtensions.Unwrap TaskExtensions.Unwrap Method

Définition

Surcharges

Unwrap(Task<Task>) Unwrap(Task<Task>) Unwrap(Task<Task>)

Crée un proxy Task qui représente l'opération asynchrone d'une TryExecuteTaskInline(Task, Boolean).Creates a proxy Task that represents the asynchronous operation of a TryExecuteTaskInline(Task, Boolean).

Unwrap<TResult>(Task<Task<TResult>>) Unwrap<TResult>(Task<Task<TResult>>) Unwrap<TResult>(Task<Task<TResult>>) Unwrap<TResult>(Task<Task<TResult>>)

Crée un proxy Task qui représente l'opération asynchrone d'un Task<Task<T>> (en C#) ou Task (Of Task(Of T)) (en Visual Basic).Creates a proxy Task that represents the asynchronous operation of a Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic).

Unwrap(Task<Task>) Unwrap(Task<Task>) Unwrap(Task<Task>)

Crée un proxy Task qui représente l'opération asynchrone d'une TryExecuteTaskInline(Task, Boolean).Creates a proxy Task that represents the asynchronous operation of a TryExecuteTaskInline(Task, Boolean).

public:
[System::Runtime::CompilerServices::Extension]
 static System::Threading::Tasks::Task ^ Unwrap(System::Threading::Tasks::Task<System::Threading::Tasks::Task ^> ^ task);
public static System.Threading.Tasks.Task Unwrap (this System.Threading.Tasks.Task<System.Threading.Tasks.Task> task);
static member Unwrap : System.Threading.Tasks.Task<System.Threading.Tasks.Task> -> System.Threading.Tasks.Task

Paramètres

task
Task<Task>

Le Task<Task> (C#) ou Task (Of Task) (Visual Basic) à défaire.The Task<Task> (C#) or Task (Of Task) (Visual Basic) to unwrap.

Retours

Tâche qui représente l'opération asynchrone de la System.Threading.Tasks.Task(Of Task) fournie.A Task that represents the asynchronous operation of the provided System.Threading.Tasks.Task(Of Task).

Exceptions

L'exception levée si l'argument task est null.The exception that is thrown if the task argument is null.

Exemples

L’exemple suivant montre comment désencapsuler une tâche:The following example shows how to unwrap a task:

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

class UnWrapDemo
{
     // Demonstrated features:
        //		Task.Unwrap()
        // 		Task.Factory.StartNew()
        //		Task.ContinueWith()
        // Expected results:
        // 		Indicates that continuation chains can be set up virtually instantaneously using Unwrap(), and then left to run on their own.
        //      The results of the RemoteIncrement(0) chain and the RemoteIncrement(4) chain may be intermixed with each other.
        //		The results of the sequence that starts with RemoteIncrement(4) are in strict order.
        // Documentation:
        //		http://msdn.microsoft.com/library/dd781129(VS.100).aspx
        // More information:
        //		http://blogs.msdn.com/pfxteam/archive/2009/11/04/9917581.aspx
        // Other notes:
        //		The combination of Task<T>, ContinueWith() and Unwrap() can be particularly useful for setting up a chain of long-running
        //      tasks where each task uses the results of its predecessor.
        static void Main()
        {
            // Invoking individual tasks is straightforward
            Task<int> t1 = RemoteIncrement(0);
            Console.WriteLine("Started RemoteIncrement(0)");

            // Chain together the results of (simulated) remote operations.
            // The use of Unwrap() instead of .Result below prevents this thread from blocking while setting up this continuation chain.
            Task<int> t2 = RemoteIncrement(4)
                .ContinueWith(t => RemoteIncrement(t.Result))			// RemoteIncrement() returns Task<int> so no unwrapping is needed for the first continuation.
                .Unwrap().ContinueWith(t => RemoteIncrement(t.Result))	// ContinueWith() returns Task<Task<int>>. Therefore unwrapping is needed.
                .Unwrap().ContinueWith(t => RemoteIncrement(t.Result))	// and on it goes...
                .Unwrap();
            Console.WriteLine("Started RemoteIncrement(...(RemoteIncrement(RemoteIncrement(4))...)");

            try
            {
                t1.Wait();
                Console.WriteLine("Finished RemoteIncrement(0)\n");

                t2.Wait();
                Console.WriteLine("Finished RemoteIncrement(...(RemoteIncrement(RemoteIncrement(4))...)");
            }
            catch (AggregateException e)
            {
                Console.WriteLine("A task has thrown the following (unexpected) exception:\n{0}", e);
            }

        }
        // This method represents a remote API.
        static Task<int> RemoteIncrement(int n)
        {
            return Task<int>.Factory.StartNew(
                (obj) =>
                {
                    // Simulate a slow operation
                    Thread.Sleep(1 * 1000);

                    int x = (int)obj;
                    Console.WriteLine("Thread={0}, Next={1}", Thread.CurrentThread.ManagedThreadId, ++x);
                    return x;
                },
                n);
        }
      
}

Imports System.Threading
Imports System.Threading.Tasks

Module UnwrapDemo
    ' Demonstrated features:
    '   Task.Unwrap()
    '    Task.Factory.StartNew()
    '   Task.ContinueWith()
    ' Expected results:
    ' 	Indicates that continuation chains can be set up virtually instantaneously using Unwrap(), and then left to run on their own.
    '   The results of the RemoteIncrement(0) chain and the RemoteIncrement(4) chain may be intermixed with each other.
    '   The results of the sequence that starts with RemoteIncrement(4) are in strict order.
    ' Documentation:
    '   http://msdn.microsoft.com/library/dd781129(VS.100).aspx
    ' More information:
    '   http://blogs.msdn.com/pfxteam/archive/2009/11/04/9917581.aspx
    ' Other notes:
    '   The combination of Task<T>, ContinueWith() and Unwrap() can be particularly useful for setting up a chain of long-running
    '   tasks where each task uses the results of its predecessor.

    Sub Main()
        ' Invoking individual tasks is straightforward
        Dim t1 As Task(Of Integer) = RemoteIncrement(0)
        Console.WriteLine("Started RemoteIncrement(0)")

        ' Chain together the results of (simulated) remote operations.
        ' The use of Unwrap() instead of .Result below prevents this thread from blocking while setting up this continuation chain.
        ' RemoteIncrement() returns Task<int> so no unwrapping is needed for the first continuation.
        ' ContinueWith() here returns Task<Task<int>>. Therefore unwrapping is needed.
        ' and on it goes...
        Dim t2 As Task(Of Integer) = RemoteIncrement(4).ContinueWith(Function(t) RemoteIncrement(t.Result)).Unwrap().ContinueWith(Function(t) RemoteIncrement(t.Result)).Unwrap().ContinueWith(Function(t) RemoteIncrement(t.Result)).Unwrap()
        Console.WriteLine("Started RemoteIncrement(...(RemoteIncrement(RemoteIncrement(4))...)")

        Try
            t1.Wait()
            Console.WriteLine("Finished RemoteIncrement(0)" & vbLf)

            t2.Wait()
            Console.WriteLine("Finished RemoteIncrement(...(RemoteIncrement(RemoteIncrement(4))...)")
        Catch e As AggregateException
            Console.WriteLine("A task has thrown the following (unexpected) exception:" & vbLf & "{0}", e)

        End Try
    End Sub

    ' This method represents a remote API.
    Function RemoteIncrement(ByVal n As Integer) As Task(Of Integer)
        Return Task(Of Integer).Factory.StartNew(Function(obj)
                                                     ' Simulate a slow operation
                                                     Thread.Sleep(1 * 1000)

                                                     Dim x As Integer = CInt(obj)
                                                     Console.WriteLine("Thread={0}, Next={1}", Thread.CurrentThread.ManagedThreadId, System.Threading.Interlocked.Increment(x))
                                                     Return x
                                                 End Function, n)
    End Function


End Module

Remarques

Il est souvent utile de pouvoir retourner une tâche à partir d’un Task<TResult>, où la tâche interne représente le travail effectué dans le cadre du Task<TResult>externe.It is often useful to be able to return a Task from a Task<TResult>, where the inner Task represents work done as part of the outer Task<TResult>. Toutefois, cela entraîne un ( Task<Task> C#) ou Task (Of Task) (Visual Basic), qui, s’il n’est pas traité avec soin, peut entraîner un comportement inattendu.However, doing so results in a Task<Task> (C#) or Task (Of Task) (Visual Basic), which, if not dealt with carefully, could produce unexpected behavior. Unwrap résout ce problème en créant une tâche de proxy qui représente l’intégralité de l’opération asynchrone d’une telle tâche.Unwrap solves this problem by creating a proxy Task that represents the entire asynchronous operation of such a task.

Voir aussi

Unwrap<TResult>(Task<Task<TResult>>) Unwrap<TResult>(Task<Task<TResult>>) Unwrap<TResult>(Task<Task<TResult>>) Unwrap<TResult>(Task<Task<TResult>>)

Crée un proxy Task qui représente l'opération asynchrone d'un Task<Task<T>> (en C#) ou Task (Of Task(Of T)) (en Visual Basic).Creates a proxy Task that represents the asynchronous operation of a Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic).

public:
generic <typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Threading::Tasks::Task<TResult> ^ Unwrap(System::Threading::Tasks::Task<System::Threading::Tasks::Task<TResult> ^> ^ task);
public static System.Threading.Tasks.Task<TResult> Unwrap<TResult> (this System.Threading.Tasks.Task<System.Threading.Tasks.Task<TResult>> task);
static member Unwrap : System.Threading.Tasks.Task<System.Threading.Tasks.Task<'Result>> -> System.Threading.Tasks.Task<'Result>
<Extension()>
Public Function Unwrap(Of TResult) (task As Task(Of Task(Of TResult))) As Task(Of TResult)

Paramètres de type

TResult

Type du résultat de la tâche.The type of the task's result.

Paramètres

task
Task<Task<TResult>>

Le Task<Task<T>> (C#) ou Task (Of Task(Of T)) (Visual Basic) à défaire.The Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic) to unwrap.

Retours

Un Task qui représente l'opération asynchrone du Task<Task<T>> fourni (C#) ou Task (Of Task(Of T)) (Visual Basic).A Task that represents the asynchronous operation of the provided Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic).

Exceptions

L'exception levée si l'argument task est null.The exception that is thrown if the task argument is null.

Remarques

Il est souvent utile de pouvoir retourner Task un à partir d’un Task, où le interne Task représente le travail effectué dans le cadre du externe. TaskIt is often useful to be able to return a Task from a Task, where the inner Task represents work done as part of the outer Task. Toutefois, cela entraîne un ( Task<Task<T>> C#) ou Task (Of Task(Of T)) (Visual Basic), qui, s’il n’est pas traité avec soin, peut entraîner un comportement inattendu.However, doing so results in a Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic), which, if not dealt with carefully, could produce unexpected behavior. Unwrap résout ce problème en créant un proxy Task<TResult> qui représente l’intégralité de l’opération asynchrone de Task<Task<T>> ceC#() Task (Of Task(Of T)) ou (Visual Basic).Unwrap solves this problem by creating a proxy Task<TResult> that represents the entire asynchronous operation of such a Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic).

Voir aussi

S’applique à