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TaskExtensions.Unwrap Método

  • Referencia

Definición

Espacio de nombres:
System.Threading.Tasks
Ensamblado:
System.Threading.Tasks.dll
Ensamblado:
System.Runtime.dll
Ensamblado:
System.Core.dll
Ensamblado:
netstandard.dll

Sobrecargas

Unwrap(Task<Task>)

Crea una Task de proxy que representa la operación asincrónica de Task<Task> (C#) o Task (Of Task) (Visual Basic).
Unwrap<TResult>(Task<Task<TResult>>)

Crea una Task de proxy que representa la operación asincrónica de Task<Task<T>> (C#) o Task (Of Task(Of T)) (Visual Basic).

Unwrap(Task<Task>)

Source:
TaskExtensions.cs
Source:
TaskExtensions.cs
Source:
TaskExtensions.cs

Crea una Task de proxy que representa la operación asincrónica de Task<Task> (C#) o Task (Of Task) (Visual Basic).

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
<Extension()>
Public Function Unwrap (task As Task(Of Task)) As Task

Parámetros

task
Task<Task>

Task<Task> (C#) o Task (Of Task) (Visual Basic) que se va a desempaquetar.

Devoluciones

Task

Tarea que representa la operación asincrónica del objeto System.Threading.Tasks.Task(Of Task) proporcionado.

Excepciones

ArgumentNullException

La excepción que se produce si el argumento task es NULL.

Ejemplos

En el ejemplo siguiente se muestra cómo desencapsular una tarea:

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

Comentarios

A menudo resulta útil poder devolver una tarea de un Task<TResult>objeto , donde la tarea interna representa el trabajo realizado como parte del elemento externo Task<TResult>. Sin embargo, al hacerlo, se produce un Task<Task> comportamiento inesperado (C#) o Task (Of Task) (Visual Basic), que, si no se trata con cuidado, podría producir un comportamiento inesperado. Unwrap resuelve este problema mediante la creación de una tarea de proxy que representa toda la operación asincrónica de dicha tarea.

Consulte también

Se aplica a

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

Source:
TaskExtensions.cs
Source:
TaskExtensions.cs
Source:
TaskExtensions.cs

Crea una Task de proxy que representa la operación asincrónica de Task<Task<T>> (C#) o 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)

Parámetros de tipo

TResult

Tipo del resultado de la tarea.

Parámetros

task
Task<Task<TResult>>

Task<Task<T>> (C#) o Task (Of Task(Of T)) (Visual Basic) que se va a desempaquetar.

Devoluciones

Task<TResult>

Task que representa la operación asincrónica del Task<Task<T>> (C#) o Task (Of Task(Of T)) (Visual Basic) proporcionado.

Excepciones

ArgumentNullException

La excepción que se produce si el argumento task es NULL.

Comentarios

A menudo resulta útil poder devolver un Task desde , Taskdonde el interior Task representa el trabajo realizado como parte del exterior Task. Sin embargo, al hacerlo, se produce un Task<Task<T>> comportamiento inesperado (C#) o Task (Of Task(Of T)) (Visual Basic), que, si no se trata con cuidado, podría producir un comportamiento inesperado. Unwrap resuelve este problema mediante la creación de un proxy Task<TResult> que representa toda la operación asincrónica de este tipo Task<Task<T>> (C#) o Task (Of Task(Of T)) (Visual Basic).

Consulte también

Se aplica a