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

Определение

Перегрузки

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

Создает прокси-объект Task, представляющий асинхронную операцию задачи 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>>)

Создает прокси-объект Task, представляющий асинхронную операцию задачи Task<Task<T>> (C#) или 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>)

Создает прокси-объект Task, представляющий асинхронную операцию задачи 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

Параметры

task
Task<Task>

Task<Task> (C#) или Task (Of Task) (Visual Basic) для извлечения из оболочки.The Task<Task> (C#) or Task (Of Task) (Visual Basic) to unwrap.

Возвраты

Задача, представляющая асинхронную операцию предоставленной задачи System.Threading.Tasks.Task(Of Task).A Task that represents the asynchronous operation of the provided System.Threading.Tasks.Task(Of Task).

Исключения

Исключение, которое возникает, если аргумент task равен null.The exception that is thrown if the task argument is null.

Примеры

В следующем примере показано, как расобернуть задачу: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

Комментарии

Часто бывает полезно иметь возможность возвращать задачу из Task<TResult>, где внутренняя задача представляет работу, выполненную как часть внешнего. 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>. Однако это приводит к Task<Task> появлению непредвиденного поведения в (C#) или Task (Of Task) (Visual Basic).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 решает эту проблему, создавая задачу-посредник, которая представляет всю асинхронную операцию такой задачи.Unwrap solves this problem by creating a proxy Task that represents the entire asynchronous operation of such a task.

Дополнительно

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

Создает прокси-объект Task, представляющий асинхронную операцию задачи Task<Task<T>> (C#) или 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)

Параметры типа

TResult

Тип результата задачи.The type of the task's result.

Параметры

task
Task<Task<TResult>>

Task<Task<T>> (C#) или Task (Of Task(Of T)) (Visual Basic) для извлечения из оболочки.The Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic) to unwrap.

Возвраты

Задача Task, представляющая асинхронную операцию предоставленной задачи Task<Task<T>> (C#) или 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).

Исключения

Исключение, которое возникает, если аргумент task равен null.The exception that is thrown if the task argument is null.

Комментарии

Часто бывает полезно иметь возможность возвращать Task Taskиз, где внутренняя Task часть представляет работу, выполненную в составе внешнего 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. Однако это приводит к Task<Task<T>> появлению непредвиденного поведения в (C#) или Task (Of Task(Of T)) (Visual Basic).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 решает эту проблему, создавая прокси-сервер Task<TResult> , который представляет всю асинхронную операцию Task<Task<T>> такого класса (C#) или 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).

Дополнительно

Применяется к