EventWaitHandle.Set Methode

public:
 bool Set();

public bool Set();

member this.Set : unit -> bool

Public Function Set () As Boolean

Gibt zurück

truewenn der Vorgang erfolgreich ist; andernfalls . false

Ausnahmen

Beispiele

Im folgenden Codebeispiel wird die SignalAndWait(WaitHandle, WaitHandle) Methodenüberladung verwendet, um dem Hauptthread das Signal eines blockierten Threads zu ermöglichen und dann zu warten, bis der Thread eine Aufgabe beendet hat.

Das Beispiel startet fünf Threads und ermöglicht es ihnen, für ein EventWaitHandle erstelltes Element mit der EventResetMode.AutoReset Kennzeichnung zu blockieren, und gibt dann jedes Mal, wenn der Benutzer die EINGABETASTE drückt, einen Thread los. Im Beispiel werden dann weitere fünf Threads in die Warteschlange gestellt und alle mit der EventWaitHandleEventResetMode.ManualReset Kennzeichnung erstellt.

using System;
using System.Threading;

public class Example
{
    // The EventWaitHandle used to demonstrate the difference
    // between AutoReset and ManualReset synchronization events.
    //
    private static EventWaitHandle ewh;

    // A counter to make sure all threads are started and
    // blocked before any are released. A Long is used to show
    // the use of the 64-bit Interlocked methods.
    //
    private static long threadCount = 0;

    // An AutoReset event that allows the main thread to block
    // until an exiting thread has decremented the count.
    //
    private static EventWaitHandle clearCount = 
        new EventWaitHandle(false, EventResetMode.AutoReset);

    [MTAThread]
    public static void Main()
    {
        // Create an AutoReset EventWaitHandle.
        //
        ewh = new EventWaitHandle(false, EventResetMode.AutoReset);

        // Create and start five numbered threads. Use the
        // ParameterizedThreadStart delegate, so the thread
        // number can be passed as an argument to the Start 
        // method.
        for (int i = 0; i <= 4; i++)
        {
            Thread t = new Thread(
                new ParameterizedThreadStart(ThreadProc)
            );
            t.Start(i);
        }

        // Wait until all the threads have started and blocked.
        // When multiple threads use a 64-bit value on a 32-bit
        // system, you must access the value through the
        // Interlocked class to guarantee thread safety.
        //
        while (Interlocked.Read(ref threadCount) < 5)
        {
            Thread.Sleep(500);
        }

        // Release one thread each time the user presses ENTER,
        // until all threads have been released.
        //
        while (Interlocked.Read(ref threadCount) > 0)
        {
            Console.WriteLine("Press ENTER to release a waiting thread.");
            Console.ReadLine();

            // SignalAndWait signals the EventWaitHandle, which
            // releases exactly one thread before resetting, 
            // because it was created with AutoReset mode. 
            // SignalAndWait then blocks on clearCount, to 
            // allow the signaled thread to decrement the count
            // before looping again.
            //
            WaitHandle.SignalAndWait(ewh, clearCount);
        }
        Console.WriteLine();

        // Create a ManualReset EventWaitHandle.
        //
        ewh = new EventWaitHandle(false, EventResetMode.ManualReset);

        // Create and start five more numbered threads.
        //
        for(int i=0; i<=4; i++)
        {
            Thread t = new Thread(
                new ParameterizedThreadStart(ThreadProc)
            );
            t.Start(i);
        }

        // Wait until all the threads have started and blocked.
        //
        while (Interlocked.Read(ref threadCount) < 5)
        {
            Thread.Sleep(500);
        }

        // Because the EventWaitHandle was created with
        // ManualReset mode, signaling it releases all the
        // waiting threads.
        //
        Console.WriteLine("Press ENTER to release the waiting threads.");
        Console.ReadLine();
        ewh.Set();
    }

    public static void ThreadProc(object data)
    {
        int index = (int) data;

        Console.WriteLine("Thread {0} blocks.", data);
        // Increment the count of blocked threads.
        Interlocked.Increment(ref threadCount);

        // Wait on the EventWaitHandle.
        ewh.WaitOne();

        Console.WriteLine("Thread {0} exits.", data);
        // Decrement the count of blocked threads.
        Interlocked.Decrement(ref threadCount);

        // After signaling ewh, the main thread blocks on
        // clearCount until the signaled thread has 
        // decremented the count. Signal it now.
        //
        clearCount.Set();
    }
}

Imports System.Threading

Public Class Example

    ' The EventWaitHandle used to demonstrate the difference
    ' between AutoReset and ManualReset synchronization events.
    '
    Private Shared ewh As EventWaitHandle

    ' A counter to make sure all threads are started and
    ' blocked before any are released. A Long is used to show
    ' the use of the 64-bit Interlocked methods.
    '
    Private Shared threadCount As Long = 0

    ' An AutoReset event that allows the main thread to block
    ' until an exiting thread has decremented the count.
    '
    Private Shared clearCount As New EventWaitHandle(False, _
        EventResetMode.AutoReset)

    <MTAThread> _
    Public Shared Sub Main()

        ' Create an AutoReset EventWaitHandle.
        '
        ewh = New EventWaitHandle(False, EventResetMode.AutoReset)

        ' Create and start five numbered threads. Use the
        ' ParameterizedThreadStart delegate, so the thread
        ' number can be passed as an argument to the Start 
        ' method.
        For i As Integer = 0 To 4
            Dim t As New Thread(AddressOf ThreadProc)
            t.Start(i)
        Next i

        ' Wait until all the threads have started and blocked.
        ' When multiple threads use a 64-bit value on a 32-bit
        ' system, you must access the value through the
        ' Interlocked class to guarantee thread safety.
        '
        While Interlocked.Read(threadCount) < 5
            Thread.Sleep(500)
        End While

        ' Release one thread each time the user presses ENTER,
        ' until all threads have been released.
        '
        While Interlocked.Read(threadCount) > 0
            Console.WriteLine("Press ENTER to release a waiting thread.")
            Console.ReadLine()

            ' SignalAndWait signals the EventWaitHandle, which
            ' releases exactly one thread before resetting, 
            ' because it was created with AutoReset mode. 
            ' SignalAndWait then blocks on clearCount, to 
            ' allow the signaled thread to decrement the count
            ' before looping again.
            '
            WaitHandle.SignalAndWait(ewh, clearCount)
        End While
        Console.WriteLine()

        ' Create a ManualReset EventWaitHandle.
        '
        ewh = New EventWaitHandle(False, EventResetMode.ManualReset)

        ' Create and start five more numbered threads.
        '
        For i As Integer = 0 To 4
            Dim t As New Thread(AddressOf ThreadProc)
            t.Start(i)
        Next i

        ' Wait until all the threads have started and blocked.
        '
        While Interlocked.Read(threadCount) < 5
            Thread.Sleep(500)
        End While

        ' Because the EventWaitHandle was created with
        ' ManualReset mode, signaling it releases all the
        ' waiting threads.
        '
        Console.WriteLine("Press ENTER to release the waiting threads.")
        Console.ReadLine()
        ewh.Set()
        
    End Sub

    Public Shared Sub ThreadProc(ByVal data As Object)
        Dim index As Integer = CInt(data)

        Console.WriteLine("Thread {0} blocks.", data)
        ' Increment the count of blocked threads.
        Interlocked.Increment(threadCount)

        ' Wait on the EventWaitHandle.
        ewh.WaitOne()

        Console.WriteLine("Thread {0} exits.", data)
        ' Decrement the count of blocked threads.
        Interlocked.Decrement(threadCount)

        ' After signaling ewh, the main thread blocks on
        ' clearCount until the signaled thread has 
        ' decremented the count. Signal it now.
        '
        clearCount.Set()
    End Sub
End Class

Hinweise

Bei einem EventWaitHandle Mit EventResetMode.AutoReset (einschließlich AutoResetEvent) gibt die Set Methode einen einzelnen Thread frei. Wenn keine Wartethreads vorhanden sind, bleibt der Wartepunkt signalisiert, bis ein Thread versucht, darauf zu warten, oder bis die Reset Methode aufgerufen wird.

Bei einem EventWaitHandle Mit EventResetMode.ManualReset (einschließlich ManualResetEvent) verlässt das Aufrufen der Set Methode den Wartepunkt in einem signalisierten Zustand, bis die Reset Methode aufgerufen wird.

Weitere Informationen

• Übersicht über Synchronisierungsgrundtypen