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

Definizione

Rappresenta il lato producer di un oggetto Task<TResult> non associato a un delegato, fornendo l'accesso al lato consumer tramite la proprietà 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)

Parametri di tipo

TResult

Tipo del valore risultante associato a questo TaskCompletionSource<TResult>.The type of the result value associated with this TaskCompletionSource<TResult>.

Ereditarietà
TaskCompletionSource<TResult>TaskCompletionSource<TResult>TaskCompletionSource<TResult>TaskCompletionSource<TResult>

Esempi

Nell'esempio seguente viene illustrato come utilizzare un TaskCompletionSource<TResult>oggetto: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

Commenti

In molti scenari è utile abilitare un oggetto Task<TResult> per rappresentare un'operazione asincrona esterna.In many scenarios, it is useful to enable a Task<TResult> to represent an external asynchronous operation. TaskCompletionSource<TResult>viene fornito a questo scopo.TaskCompletionSource<TResult> is provided for this purpose. Consente la creazione di un'attività che può essere distribuita agli utenti.It enables the creation of a task that can be handed out to consumers. I consumer possono utilizzare i membri dell'attività allo stesso modo di qualsiasi altra variabile membro dell'attività di gestione dello scenario.The consumers can use the members of the task the same way as they would in any other scenario handling task member variables. Tuttavia, a differenza della maggior parte delle attività, lo stato di un'attività creata da un TaskCompletionSource viene controllato in modo esplicito dai metodi in TaskCompletionSource.However, unlike most tasks, the state of a task created by a TaskCompletionSource is controlled explicitly by the methods on TaskCompletionSource. Questo consente il completamento dell'operazione asincrona esterna da propagare all'attività sottostante.This enables the completion of the external asynchronous operation to be propagated to the underlying Task. La separazione garantisce inoltre che i consumer non siano in grado di eseguire la transizione dello stato senza accedere al TaskCompletionSource corrispondente.The separation also ensures that consumers are not able to transition the state without access to the corresponding TaskCompletionSource. Per ulteriori informazioni, vedere l'articolo relativo alla natura di<TaskCompletionSource TResult > nel Blog sulla programmazione parallela con .NET.For more information, see the entry The Nature of TaskCompletionSource<TResult> in the Parallel Programming with .NET blog.

Gli esempi di estensioni parallele contengono anche esempi di utilizzo TaskCompletionSource<TResult>di.The Parallel Extensions samples also contain examples of how to use TaskCompletionSource<TResult>.

Costruttori

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

Crea un oggetto TaskCompletionSource<TResult>.Creates a TaskCompletionSource<TResult>.

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

Crea un oggetto TaskCompletionSource<TResult> con lo stato specificato.Creates a TaskCompletionSource<TResult> with the specified state.

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

Crea un oggetto TaskCompletionSource<TResult> con lo stato e le opzioni specificate.Creates a TaskCompletionSource<TResult> with the specified state and options.

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

Crea un oggetto TaskCompletionSource<TResult> con le opzioni specificate.Creates a TaskCompletionSource<TResult> with the specified options.

Proprietà

Task Task Task Task

Ottiene l'oggetto Task<TResult> creato da questo oggetto TaskCompletionSource<TResult>.Gets the Task<TResult> created by this TaskCompletionSource<TResult>.

Metodi

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

Determina se l'oggetto specificato è uguale all'oggetto corrente.Determines whether the specified object is equal to the current object.

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

Funge da funzione hash predefinita.Serves as the default hash function.

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

Ottiene l'oggetto Type dell'istanza corrente.Gets the Type of the current instance.

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

Crea una copia superficiale dell'oggetto Object corrente.Creates a shallow copy of the current Object.

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

Esegue la transizione dell'oggetto Task<TResult> sottostante allo stato Canceled.Transitions the underlying Task<TResult> into the Canceled state.

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

Esegue la transizione dell'oggetto Task<TResult> sottostante allo stato Faulted e associa questo oggetto a un'eccezione specificata.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>)

Esegue la transizione dell'oggetto Task<TResult> sottostante allo stato Faulted e associa all'oggetto una raccolta di eccezioni.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)

Esegue la transizione dell'oggetto Task<TResult> sottostante allo stato RanToCompletion.Transitions the underlying Task<TResult> into the RanToCompletion state.

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

Restituisce una stringa che rappresenta l'oggetto corrente.Returns a string that represents the current object.

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

Tenta di eseguire la transizione dell'oggetto Task<TResult> sottostante allo stato Canceled.Attempts to transition the underlying Task<TResult> into the Canceled state.

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

Tenta di eseguire la transizione dell'oggetto Task<TResult> sottostante allo stato Canceled e abilita l'archiviazione di un token di annullamento nell'attività annullata.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)

Tenta di eseguire la transizione dell'oggetto Task<TResult> sottostante allo stato Faulted e associa tale oggetto a un'eccezione specificata.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>)

Tenta di eseguire la transizione dell'oggetto Task<TResult> sottostante allo stato Faulted e associa a questo oggetto una raccolta di eccezioni.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)

Tenta di eseguire la transizione dell'oggetto Task<TResult> sottostante allo stato RanToCompletion.Attempts to transition the underlying Task<TResult> into the RanToCompletion state.

Si applica a

Thread safety

Tutti i membri TaskCompletionSource<TResult> di sono thread-safe e possono essere usati contemporaneamente da più thread.All members of TaskCompletionSource<TResult> are thread-safe and may be used from multiple threads concurrently.

Vedi anche