WaitOrTimerCallback WaitOrTimerCallback WaitOrTimerCallback WaitOrTimerCallback Delegate

Definition

Stellt eine Methode dar, die aufgerufen werden soll, wenn ein Signal an ein WaitHandle gesendet wird oder dessen Timeout überschritten ist.Represents a method to be called when a WaitHandle is signaled or times out.

public delegate void WaitOrTimerCallback(System::Object ^ state, bool timedOut);
[System.Runtime.InteropServices.ComVisible(true)]
public delegate void WaitOrTimerCallback(object state, bool timedOut);
type WaitOrTimerCallback = delegate of obj * bool -> unit
Public Delegate Sub WaitOrTimerCallback(state As Object, timedOut As Boolean)

Parameter

state
Object Object Object Object

Ein Objekt mit den Informationen, die von der Rückrufmethode bei jeder Ausführung verwendet werden.An object containing information to be used by the callback method each time it executes.

timedOut
Boolean Boolean Boolean Boolean

true, wenn das Timeout für WaitHandle überschritten ist, false, wenn ein Signal gesendet wurde.true if the WaitHandle timed out; false if it was signaled.

Vererbung
WaitOrTimerCallbackWaitOrTimerCallbackWaitOrTimerCallbackWaitOrTimerCallback
Attribute

Beispiele

Im folgenden Beispiel wird gezeigt, wie der WaitOrTimerCallback -Delegat verwendet wird, um eine Rückruf Methode darzustellen, die ausgeführt wird, wenn ein Wait-Handle signalisiert wird.The following example shows how to use the WaitOrTimerCallback delegate to represent a callback method that is executed when a wait handle is signaled.

Das Beispiel zeigt auch, wie die RegisterWaitForSingleObject -Methode verwendet wird, um eine angegebene Rückruf Methode auszuführen, wenn ein angegebenes Wait-Handle signalisiert wird.The example also shows how to use the RegisterWaitForSingleObject method to execute a specified callback method when a specified wait handle is signaled. In diesem Beispiel ist WaitProc die Rückruf Methode, und das Wait-Handle ist ein. AutoResetEventIn this example, the callback method is WaitProc and the wait handle is an AutoResetEvent.

Im Beispiel wird eine TaskInfo -Klasse definiert, die die Informationen enthält, die bei der Ausführung an den Rückruf übermittelt werden.The example defines a TaskInfo class to hold the information that is passed to the callback when it executes. Im Beispiel wird ein TaskInfo -Objekt erstellt, und es werden Zeichen folgen Daten zugewiesen.The example creates a TaskInfo object and assigns it some string data. Der RegisteredWaitHandle , der von der RegisterWaitForSingleObject -Methode zurückgegeben wird, Handle wird dem- TaskInfo Feld des- RegisteredWaitHandleObjekts zugewiesen, sodass die Rückruf Methode Zugriff auf hat.The RegisteredWaitHandle that is returned by the RegisterWaitForSingleObject method is assigned to the Handle field of the TaskInfo object, so that the callback method has access to the RegisteredWaitHandle.

Zusätzlich TaskInfo zum-Objekt gibt der Aufruf RegisterWaitForSingleObject der-Methode den AutoResetEvent an, auf den der Task wartet, WaitOrTimerCallback einen Delegaten, WaitProc der die Rückruf Methode darstellt, ein Timeout Intervall von einer Sekunde und mehrere Rückrufe. .In addition to the TaskInfo object, the call to the RegisterWaitForSingleObject method specifies the AutoResetEvent the task waits on, a WaitOrTimerCallback delegate that represents the WaitProc callback method, a one-second timeout interval, and multiple callbacks.

Wenn der Haupt Thread AutoResetEvent durch Aufrufen seiner Set -Methode signalisiert, wird WaitOrTimerCallback der Delegat aufgerufen.When the main thread signals the AutoResetEvent by calling its Set method, the WaitOrTimerCallback delegate is invoked. Die WaitProc -Methode RegisteredWaitHandle testet, ob ein Timeout aufgetreten ist.The WaitProc method tests RegisteredWaitHandle to determine whether a timeout occurred. Wenn der Rückruf aufgerufen wurde, weil das Wait-Handle signalisiert wurde WaitProc , hebt die Methode RegisteredWaitHandledie Registrierung des auf und beendet weitere Rückrufe.If the callback was invoked because the wait handle was signaled, the WaitProc method unregisters the RegisteredWaitHandle, stopping further callbacks. Im Falle eines Timeouts wartet der Task weiterhin.In the case of a timeout, the task continues waiting. Die WaitProc Methode wird beendet, indem eine Meldung an die Konsole ausgegeben wird.The WaitProc method ends by printing a message to the console.

using namespace System;
using namespace System::Threading;

// TaskInfo contains data that will be passed to the callback
// method.
public ref class TaskInfo
{
public:
   TaskInfo()
   {
      Handle = nullptr;
      OtherInfo = "default";
   }

   RegisteredWaitHandle^ Handle;
   String^ OtherInfo;
};

ref class Example
{
public:

   // The callback method executes when the registered wait times out,
   // or when the WaitHandle (in this case AutoResetEvent) is signaled.
   // WaitProc unregisters the WaitHandle the first time the event is 
   // signaled.
   static void WaitProc( Object^ state, bool timedOut )
   {
      
      // The state Object must be cast to the correct type, because the
      // signature of the WaitOrTimerCallback delegate specifies type
      // Object.
      TaskInfo^ ti = static_cast<TaskInfo^>(state);
      String^ cause = "TIMED OUT";
      if (  !timedOut )
      {
         cause = "SIGNALED";
         
         // If the callback method executes because the WaitHandle is
         // signaled, stop future execution of the callback method
         // by unregistering the WaitHandle.
         if ( ti->Handle != nullptr )
                  ti->Handle->Unregister( nullptr );
      }

      Console::WriteLine( "WaitProc( {0}) executes on thread {1}; cause = {2}.", ti->OtherInfo, Thread::CurrentThread->GetHashCode(), cause );
   }

};

int main()
{
   
   // The main thread uses AutoResetEvent to signal the
   // registered wait handle, which executes the callback
   // method.
   AutoResetEvent^ ev = gcnew AutoResetEvent( false );
   TaskInfo^ ti = gcnew TaskInfo;
   ti->OtherInfo = "First task";
   
   // The TaskInfo for the task includes the registered wait
   // handle returned by RegisterWaitForSingleObject.  This
   // allows the wait to be terminated when the object has
   // been signaled once (see WaitProc).
   ti->Handle = ThreadPool::RegisterWaitForSingleObject( ev, gcnew WaitOrTimerCallback( Example::WaitProc ), ti, 1000, false );
   
   // The main thread waits three seconds, to demonstrate the
   // time-outs on the queued thread, and then signals.
   Thread::Sleep( 3100 );
   Console::WriteLine( "Main thread signals." );
   ev->Set();
   
   // The main thread sleeps, which should give the callback
   // method time to execute.  If you comment out this line, the
   // program usually ends before the ThreadPool thread can execute.
   Thread::Sleep( 1000 );
   
   // If you start a thread yourself, you can wait for it to end
   // by calling Thread::Join.  This option is not available with 
   // thread pool threads.
   return 0;
}

using System;
using System.Threading;

// TaskInfo contains data that will be passed to the callback
// method.
public class TaskInfo {
    public RegisteredWaitHandle Handle = null;
    public string OtherInfo = "default";
}

public class Example {
    public static void Main(string[] args) {
        // The main thread uses AutoResetEvent to signal the
        // registered wait handle, which executes the callback
        // method.
        AutoResetEvent ev = new AutoResetEvent(false);

        TaskInfo ti = new TaskInfo();
        ti.OtherInfo = "First task";
        // The TaskInfo for the task includes the registered wait
        // handle returned by RegisterWaitForSingleObject.  This
        // allows the wait to be terminated when the object has
        // been signaled once (see WaitProc).
        ti.Handle = ThreadPool.RegisterWaitForSingleObject(
            ev,
            new WaitOrTimerCallback(WaitProc),
            ti,
            1000,
            false
        );

        // The main thread waits three seconds, to demonstrate the
        // time-outs on the queued thread, and then signals.
        Thread.Sleep(3100);
        Console.WriteLine("Main thread signals.");
        ev.Set();

        // The main thread sleeps, which should give the callback
        // method time to execute.  If you comment out this line, the
        // program usually ends before the ThreadPool thread can execute.
        Thread.Sleep(1000);
        // If you start a thread yourself, you can wait for it to end
        // by calling Thread.Join.  This option is not available with 
        // thread pool threads.
    }
   
    // The callback method executes when the registered wait times out,
    // or when the WaitHandle (in this case AutoResetEvent) is signaled.
    // WaitProc unregisters the WaitHandle the first time the event is 
    // signaled.
    public static void WaitProc(object state, bool timedOut) {
        // The state object must be cast to the correct type, because the
        // signature of the WaitOrTimerCallback delegate specifies type
        // Object.
        TaskInfo ti = (TaskInfo) state;

        string cause = "TIMED OUT";
        if (!timedOut) {
            cause = "SIGNALED";
            // If the callback method executes because the WaitHandle is
            // signaled, stop future execution of the callback method
            // by unregistering the WaitHandle.
            if (ti.Handle != null)
                ti.Handle.Unregister(null);
        } 

        Console.WriteLine("WaitProc( {0} ) executes on thread {1}; cause = {2}.",
            ti.OtherInfo, 
            Thread.CurrentThread.GetHashCode().ToString(), 
            cause
        );
    }
}
Imports System.Threading

' TaskInfo contains data that will be passed to the callback
' method.
Public Class TaskInfo
    public Handle As RegisteredWaitHandle = Nothing
    public OtherInfo As String = "default"
End Class

Public Class Example

    <MTAThread> _
    Public Shared Sub Main()
        ' The main thread uses AutoResetEvent to signal the
        ' registered wait handle, which executes the callback
        ' method.
        Dim ev As New AutoResetEvent(false)

        Dim ti As New TaskInfo()
        ti.OtherInfo = "First task"
        ' The TaskInfo for the task includes the registered wait
        ' handle returned by RegisterWaitForSingleObject.  This
        ' allows the wait to be terminated when the object has
        ' been signaled once (see WaitProc).
        ti.Handle = ThreadPool.RegisterWaitForSingleObject( _
            ev, _
            New WaitOrTimerCallback(AddressOf WaitProc), _
            ti, _
            1000, _
            false _
        )

        ' The main thread waits about three seconds, to demonstrate 
        ' the time-outs on the queued task, and then signals.
        Thread.Sleep(3100)
        Console.WriteLine("Main thread signals.")
        ev.Set()

        ' The main thread sleeps, which should give the callback
        ' method time to execute.  If you comment out this line, the
        ' program usually ends before the ThreadPool thread can execute.
        Thread.Sleep(1000)
        ' If you start a thread yourself, you can wait for it to end
        ' by calling Thread.Join.  This option is not available with 
        ' thread pool threads.
    End Sub
   
    ' The callback method executes when the registered wait times out,
    ' or when the WaitHandle (in this case AutoResetEvent) is signaled.
    ' WaitProc unregisters the WaitHandle the first time the event is 
    ' signaled.
    Public Shared Sub WaitProc(state As Object, timedOut As Boolean)
        ' The state object must be cast to the correct type, because the
        ' signature of the WaitOrTimerCallback delegate specifies type
        ' Object.
        Dim ti As TaskInfo = CType(state, TaskInfo)

        Dim cause As String = "TIMED OUT"
        If Not timedOut Then
            cause = "SIGNALED"
            ' If the callback method executes because the WaitHandle is
            ' signaled, stop future execution of the callback method
            ' by unregistering the WaitHandle.
            If Not ti.Handle Is Nothing Then
                ti.Handle.Unregister(Nothing)
            End If
        End If 

        Console.WriteLine("WaitProc( {0} ) executes on thread {1}; cause = {2}.", _
            ti.OtherInfo, _
            Thread.CurrentThread.GetHashCode().ToString(), _
            cause _
        )
    End Sub
End Class

Hinweise

WaitOrTimerCallbackstellt eine Rückruf Methode dar, die ausgeführt werden soll, wenn bei einem registrierten Wait-Handle ein Timeout auftritt oder signalisiert wird.WaitOrTimerCallback represents a callback method that you want to execute when a registered wait handle times out or is signaled. Erstellen Sie den Delegaten, indem Sie die Rückruf WaitOrTimerCallback Methode an den-Konstruktor übergeben.Create the delegate by passing your callback method to the WaitOrTimerCallback constructor. Die-Methode muss über die hier gezeigte Signatur verfügen.Your method must have the signature shown here.

Erstellen Sie das registrierte Wait-Handle, WaitOrTimerCallback indem Sie den WaitHandle - ThreadPool.RegisterWaitForSingleObjectDelegaten und einen an übergeben.Create the registered wait handle by passing the WaitOrTimerCallback delegate and a WaitHandle to ThreadPool.RegisterWaitForSingleObject. Die WaitHandle Rückruf Methode wird jedes Mal ausgeführt, wenn ein Timeout auftritt oder signalisiert wird.Your callback method executes each time the WaitHandle times out or is signaled.

Hinweis

Visual Basic Benutzer den WaitOrTimerCallback -Konstruktor weglassen und einfach den AddressOf -Operator verwenden können, wenn Sie die Rückruf RegisterWaitForSingleObjectMethode an übergeben.Visual Basic users can omit the WaitOrTimerCallback constructor, and simply use the AddressOf operator when passing the callback method to RegisterWaitForSingleObject. Visual Basic ruft automatisch den richtigen Delegatkonstruktor auf.Visual Basic automatically calls the correct delegate constructor.

Wenn Sie Informationen an die Rückruf Methode übergeben möchten, erstellen Sie ein-Objekt, das die erforderlichen Informationen enthält, und RegisterWaitForSingleObject übergeben Sie es an, wenn Sie das registrierte Wait-Handle erstellen.If you want to pass information to your callback method, create an object that contains the necessary information and pass it to RegisterWaitForSingleObject when you create the registered wait handle. Jedes Mal, wenn die Rückruf Methode ausgeführt state wird, enthält der-Parameter dieses-Objekt.Each time your callback method executes, the state parameter contains this object.

Weitere Informationen zur Verwendung von Rückruf Methoden zum Synchronisieren von Thread Pool-Threads finden Sie unter Managed Thread Pool.For more information about using callback methods to synchronize thread pool threads, see The managed thread pool.

Erweiterungsmethoden

GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate)

Ruft ein Objekt ab, das die Methode darstellt, die vom angegebenen Delegaten dargestellt wird.Gets an object that represents the method represented by the specified delegate.

Gilt für:

Siehe auch