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

Definizione

Overload

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

Crea un oggetto proxy Task che rappresenta l'operazione asincrona di un oggetto 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>>)

Crea un oggetto Task proxy che rappresenta l'operazione asincrona di un oggetto Task<Task<T>> (C#) o Task (Of Task(Of T)) (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>)

Crea un oggetto proxy Task che rappresenta l'operazione asincrona di un oggetto 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

Parametri

task
Task<Task>

Oggetto Task<Task> (C#) o Task (Of Task) (Visual Basic) di cui annullare il wrapping.The Task<Task> (C#) or Task (Of Task) (Visual Basic) to unwrap.

Restituisce

Attività che rappresenta l'operazione asincrona dell'oggetto System.Threading.Tasks.Task(Of Task) fornito.A Task that represents the asynchronous operation of the provided System.Threading.Tasks.Task(Of Task).

Eccezioni

Eccezione generata se l'argomento task è Null.The exception that is thrown if the task argument is null.

Esempi

Nell'esempio seguente viene illustrato come annullare il wrapping di un'attività: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

Commenti

È spesso utile essere in grado di restituire un'attività da un Task<TResult>, in cui l'attività interna rappresenta il lavoro effettuato come parte dell'esterno Task<TResult>.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>. Tuttavia, questa operazione genera una Task<Task> (c#) o Task (Of Task) (Visual Basic), che, se non viene gestito con attenzione, è stato possibile generare un comportamento imprevisto.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. Annullamento del wrapping risolve questo problema creando un'attività che rappresenta l'intera operazione asincrona di tale attività proxy.Unwrap solves this problem by creating a proxy Task that represents the entire asynchronous operation of such a task.

Vedi anche

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

Crea un oggetto Task proxy che rappresenta l'operazione asincrona di un oggetto Task<Task<T>> (C#) o Task (Of Task(Of T)) (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)

Parametri di tipo

TResult

Tipo di risultato dell'attività.The type of the task's result.

Parametri

task
Task<Task<TResult>>

Oggetto Task<Task<T>> (C#) o Task (Of Task(Of T)) (Visual Basic) di cui annullare il wrapping.The Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic) to unwrap.

Restituisce

Oggetto Task che rappresenta l'operazione asincrona dell'oggetto Task<Task<T>> (C#) o Task (Of Task(Of T)) (Visual Basic) fornito.A Task that represents the asynchronous operation of the provided Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic).

Eccezioni

Eccezione generata se l'argomento task è Null.The exception that is thrown if the task argument is null.

Commenti

È spesso utile essere in grado di restituire un Task da un Task, dove interna Task rappresenta il lavoro svolto come parte dell'esterno Task.It 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. Tuttavia, questa operazione genera una Task<Task<T>> (c#) o Task (Of Task(Of T)) (Visual Basic), che, se non viene gestito con attenzione, è stato possibile generare un comportamento imprevisto.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. Annullamento del wrapping risolve questo problema creando un proxy Task<TResult> che rappresenta l'intera operazione asincrona di tali una Task<Task<T>> (c#) o Task (Of Task(Of T)) (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).

Vedi anche

Si applica a