IAsyncResult.AsyncWaitHandle IAsyncResult.AsyncWaitHandle IAsyncResult.AsyncWaitHandle IAsyncResult.AsyncWaitHandle Property

Definition

Ruft eine WaitHandle-Klasse auf, die für das Warten auf den Abschluss eines asynchronen Vorgangs verwendet wird.Gets a WaitHandle that is used to wait for an asynchronous operation to complete.

public:
 property System::Threading::WaitHandle ^ AsyncWaitHandle { System::Threading::WaitHandle ^ get(); };
public System.Threading.WaitHandle AsyncWaitHandle { get; }
member this.AsyncWaitHandle : System.Threading.WaitHandle
Public ReadOnly Property AsyncWaitHandle As WaitHandle

Eigenschaftswert

Eine WaitHandle-Klasse, die für das Warten auf den Abschluss eines asynchronen Vorgangs verwendet wird.A WaitHandle that is used to wait for an asynchronous operation to complete.

Beispiele

Im folgenden Beispiel wird veranschaulicht, wie die AsyncWaitHandle die abzurufende Eigenschaft eine WaitHandle, und Warten eines asynchronen Aufrufs für einen Delegaten auf.The following example demonstrates how to use the AsyncWaitHandle property to get a WaitHandle, and how to wait for an asynchronous call on a delegate. Das WaitHandle wird bei Beendigung des asynchronen Aufrufs signalisiert, und durch Aufrufen der WaitOne -Methode kann darauf gewartet werden.The WaitHandle is signaled when the asynchronous call completes, and you can wait for it by calling the WaitOne method.

Das Beispiel besteht aus zwei Klassen: die Klasse enthält die Methode, die asynchron aufgerufen wird und die Klasse enthält die Main -Methode, die den Aufruf ausführt.The example consists of two classes: the class that contains the method that is called asynchronously, and the class that contains the Main method that makes the call.

Weitere Informationen und Beispiele von asynchronen Aufrufen von Methoden mit Delegaten finden Sie unter Calling Synchronous Methods Asynchronously.For more information and more examples of calling methods asynchronously by using delegates, see Calling Synchronous Methods Asynchronously.

using namespace System;
using namespace System::Threading;
using namespace System::Runtime::InteropServices; 

namespace Examples {
namespace AdvancedProgramming {
namespace AsynchronousOperations
{
    public ref class AsyncDemo 
    {
    public:
        // The method to be executed asynchronously.
        String^ TestMethod(int callDuration, [OutAttribute] int% threadId) 
        {
            Console::WriteLine("Test method begins.");
            Thread::Sleep(callDuration);
            threadId = Thread::CurrentThread->ManagedThreadId;
            return String::Format("My call time was {0}.", callDuration);
        }
    };

    // The delegate must have the same signature as the method
    // it will call asynchronously.
    public delegate String^ AsyncMethodCaller(int callDuration, [OutAttribute] int% threadId);
}}}
using System;
using System.Threading; 

namespace Examples.AdvancedProgramming.AsynchronousOperations
{
    public class AsyncDemo 
    {
        // The method to be executed asynchronously.
        public string TestMethod(int callDuration, out int threadId) 
        {
            Console.WriteLine("Test method begins.");
            Thread.Sleep(callDuration);
            threadId = Thread.CurrentThread.ManagedThreadId;
            return String.Format("My call time was {0}.", callDuration.ToString());
        }
    }
    // The delegate must have the same signature as the method
    // it will call asynchronously.
    public delegate string AsyncMethodCaller(int callDuration, out int threadId);
}
Imports System
Imports System.Threading
Imports System.Runtime.InteropServices 

Namespace Examples.AdvancedProgramming.AsynchronousOperations
    Public Class AsyncDemo 
        ' The method to be executed asynchronously.
        Public Function TestMethod(ByVal callDuration As Integer, _
                <Out> ByRef threadId As Integer) As String
            Console.WriteLine("Test method begins.")
            Thread.Sleep(callDuration)
            threadId = Thread.CurrentThread.ManagedThreadId()
            return String.Format("My call time was {0}.", callDuration.ToString())
        End Function
    End Class

    ' The delegate must have the same signature as the method
    ' it will call asynchronously.
    Public Delegate Function AsyncMethodCaller(ByVal callDuration As Integer, _
        <Out> ByRef threadId As Integer) As String
End Namespace
#using <TestMethod.dll>

using namespace System;
using namespace System::Threading;
using namespace Examples::AdvancedProgramming::AsynchronousOperations;

void main() 
{
    // The asynchronous method puts the thread id here.
    int threadId;

    // Create an instance of the test class.
    AsyncDemo^ ad = gcnew AsyncDemo();

    // Create the delegate.
    AsyncMethodCaller^ caller = gcnew AsyncMethodCaller(ad, &AsyncDemo::TestMethod);
       
    // Initiate the asychronous call.
    IAsyncResult^ result = caller->BeginInvoke(3000, 
        threadId, nullptr, nullptr);

    Thread::Sleep(0);
    Console::WriteLine("Main thread {0} does some work.",
        Thread::CurrentThread->ManagedThreadId);

    // Wait for the WaitHandle to become signaled.
    result->AsyncWaitHandle->WaitOne();

    // Perform additional processing here.
    // Call EndInvoke to retrieve the results.
    String^ returnValue = caller->EndInvoke(threadId, result);

    // Close the wait handle.
    result->AsyncWaitHandle->Close();

    Console::WriteLine("The call executed on thread {0}, with return value \"{1}\".",
        threadId, returnValue);
}

/* This example produces output similar to the following:

Main thread 1 does some work.
Test method begins.
The call executed on thread 3, with return value "My call time was 3000.".
 */
using System;
using System.Threading;

namespace Examples.AdvancedProgramming.AsynchronousOperations
{
    public class AsyncMain 
    {
        static void Main() 
        {
            // The asynchronous method puts the thread id here.
            int threadId;

            // Create an instance of the test class.
            AsyncDemo ad = new AsyncDemo();

            // Create the delegate.
            AsyncMethodCaller caller = new AsyncMethodCaller(ad.TestMethod);
       
            // Initiate the asychronous call.
            IAsyncResult result = caller.BeginInvoke(3000, 
                out threadId, null, null);

            Thread.Sleep(0);
            Console.WriteLine("Main thread {0} does some work.",
                Thread.CurrentThread.ManagedThreadId);

            // Wait for the WaitHandle to become signaled.
            result.AsyncWaitHandle.WaitOne();

            // Perform additional processing here.
            // Call EndInvoke to retrieve the results.
            string returnValue = caller.EndInvoke(out threadId, result);

            // Close the wait handle.
            result.AsyncWaitHandle.Close();

            Console.WriteLine("The call executed on thread {0}, with return value \"{1}\".",
                threadId, returnValue);
        }
    }
}

/* This example produces output similar to the following:

Main thread 1 does some work.
Test method begins.
The call executed on thread 3, with return value "My call time was 3000.".
 */
Imports System
Imports System.Threading
Imports System.Runtime.InteropServices 

Namespace Examples.AdvancedProgramming.AsynchronousOperations

    Public Class AsyncMain 
        Shared Sub Main() 
            ' The asynchronous method puts the thread id here.
            Dim threadId As Integer

            ' Create an instance of the test class.
            Dim ad As New AsyncDemo()

            ' Create the delegate.
            Dim caller As New AsyncMethodCaller(AddressOf ad.TestMethod)
       
            ' Initiate the asynchronous call.
            Dim result As IAsyncResult = caller.BeginInvoke(3000, _
                threadId, Nothing, Nothing)

            Thread.Sleep(0)
            Console.WriteLine("Main thread {0} does some work.", _
                Thread.CurrentThread.ManagedThreadId)
            ' Perform additional processing here and then
            ' wait for the WaitHandle to be signaled.
            result.AsyncWaitHandle.WaitOne()

            ' Call EndInvoke to retrieve the results.
            Dim returnValue As String = caller.EndInvoke(threadId, result)

            ' Close the wait handle.
            result.AsyncWaitHandle.Close()

            Console.WriteLine("The call executed on thread {0}, with return value ""{1}"".", _
                threadId, returnValue)
        End Sub
    End Class
End Namespace

'This example produces output similar to the following:
'
'Main thread 1 does some work.
'Test method begins.
'The call executed on thread 3, with return value "My call time was 3000.".

Hinweise

Der Rückgabewert kann der Client warten, bis ein asynchroner Vorgang abgeschlossen statt Abruf IsCompleted , bis die Operation abgeschlossen ist.The return value allows the client to wait for an asynchronous operation to complete instead of polling IsCompleted until the operation concludes. Der Rückgabewert verwendet werden kann, zum Ausführen einer WaitOne, WaitAny, oder WaitAll Vorgang.The return value can be used to perform a WaitOne, WaitAny, or WaitAll operation.

Die common Language Runtime stellt eine Reihe von wartbare Objekte repräsentieren, bereit, z. B. ManualResetEvent, AutoResetEvent, und Mutex, die Win32-Synchronisierungsprimitive widerspiegeln.The common language runtime supplies a number of waitable objects, such as ManualResetEvent, AutoResetEvent, and Mutex, all of which mirror Win32 synchronization primitives.

Hinweise für Ausführende

Das Objekt, das implementiert IAsyncResult muss nicht zum Erstellen der WaitHandle erst die AsyncWaitHandle -Eigenschaft schreibgeschützt ist.The object that implements IAsyncResult does not need to create the WaitHandle until the AsyncWaitHandle property is read. Es ist die Auswahl des dem IAsyncResult Implementierung.It is the choice of the IAsyncResult implementer. Jedoch, wenn die Implementierung erstellt AsyncWaitHandle, kann die Verantwortung für die Implementierung, um zu signalisieren die WaitHandle endet, das den Wartevorgang zum richtigen Zeitpunkt.However, if the implementer creates AsyncWaitHandle, it is the responsibility of the implementer to signal the WaitHandle that will terminate the wait at the appropriate time. Z. B. AsyncResult beendet den Wartevorgang im Namen des Aufrufers, wenn eine asynchron aufgerufene Methode zurückgegeben.For example, AsyncResult terminates the wait on behalf of the caller when an asynchronously invoked method returns. Nach der Erstellung AsyncWaitHandle sollten aktiv bleiben, bis der Benutzer die Methode aufruft, der den asynchronen Vorgang abgeschlossen ist.Once created, AsyncWaitHandle should be kept alive until the user calls the method that concludes the asynchronous operation. An, die das Objekt hinter Zeit AsyncWaitHandle verworfen werden können.At that time the object behind AsyncWaitHandle can be discarded.

Hinweise für Aufrufer

Clients, die warten, bis der Vorgang abgeschlossen ist (im Gegensatz zu abrufen) verwenden diese Eigenschaft, um ein Synchronisierungsobjekt warten auf zu erhalten.Clients that wait for the operation to complete (as opposed to polling) use this property to obtain a synchronization object to wait on.

Bei Verwendung der BeginInvoke Methode eines Delegaten eine Methode asynchron aufrufen, und erhalten ein Wait-Handle aus den resultierenden IAsyncResult, es wird empfohlen, dass Sie das Wait-Handle schließen, sobald Sie ihn verwenden, durch den Aufruf fertig sind die Close() Methode.When you use the BeginInvoke method of a delegate to call a method asynchronously and obtain a wait handle from the resulting IAsyncResult, we recommend that you close the wait handle as soon as you are finished using it, by calling the Close() method. Wenn Sie einfach alle Verweise auf das Wait-Handle freigeben, werden die Systemressourcen freigegeben, wenn Garbagecollection zurückgefordert wird das Wait-Handle, aber die Garbagecollection arbeitet effizienter, wenn verwerfbare Objekte explizit geschlossen oder freigegeben werden.If you simply release all references to the wait handle, system resources are freed when garbage collection reclaims the wait handle, but garbage collection works more efficiently when disposable objects are explicitly closed or disposed. Weitere Informationen finden Sie in den Ausführungen zur AsyncWaitHandle-Eigenschaft.For more information, see the AsyncWaitHandle property.

Gilt für: