Timer.Stop Método

Definición

Deja de generar el evento Elapsed al establecer Enabled en false.

public:
 void Stop();
public void Stop ();
member this.Stop : unit -> unit
Public Sub Stop ()

Ejemplos

En el ejemplo siguiente se crea una instancia de un objeto que inicia su evento cada dos segundos System.Timers.Timer (2000 milisegundos), se configura un controlador de eventos para el evento e se inicia el Timer.Elapsed temporizador. El controlador de eventos muestra el valor de la ElapsedEventArgs.SignalTime propiedad cada vez que se genera. Cuando el usuario presiona la tecla Entrar, la aplicación llama al Stop método antes de finalizar la aplicación.

using System;
using System.Timers;

public class Example
{
   private static System.Timers.Timer aTimer;
   
   public static void Main()
   {
      SetTimer();

      Console.WriteLine("\nPress the Enter key to exit the application...\n");
      Console.WriteLine("The application started at {0:HH:mm:ss.fff}", DateTime.Now);
      Console.ReadLine();
      aTimer.Stop();
      aTimer.Dispose();
      
      Console.WriteLine("Terminating the application...");
   }

   private static void SetTimer()
   {
        // Create a timer with a two second interval.
        aTimer = new System.Timers.Timer(2000);
        // Hook up the Elapsed event for the timer. 
        aTimer.Elapsed += OnTimedEvent;
        aTimer.AutoReset = true;
        aTimer.Enabled = true;
    }

    private static void OnTimedEvent(Object source, ElapsedEventArgs e)
    {
        Console.WriteLine("The Elapsed event was raised at {0:HH:mm:ss.fff}",
                          e.SignalTime);
    }
}
// The example displays output like the following:
//       Press the Enter key to exit the application...
//
//       The application started at 09:40:29.068
//       The Elapsed event was raised at 09:40:31.084
//       The Elapsed event was raised at 09:40:33.100
//       The Elapsed event was raised at 09:40:35.100
//       The Elapsed event was raised at 09:40:37.116
//       The Elapsed event was raised at 09:40:39.116
//       The Elapsed event was raised at 09:40:41.117
//       The Elapsed event was raised at 09:40:43.132
//       The Elapsed event was raised at 09:40:45.133
//       The Elapsed event was raised at 09:40:47.148
//
//       Terminating the application...
Imports System.Timers

Public Module Example
    Private aTimer As System.Timers.Timer

    Public Sub Main()
        SetTimer()

      Console.WriteLine("{0}Press the Enter key to exit the application...{0}",
                        vbCrLf)
      Console.WriteLine("The application started at {0:HH:mm:ss.fff}",
                        DateTime.Now)
      Console.ReadLine()
      aTimer.Stop()
      aTimer.Dispose()

      Console.WriteLine("Terminating the application...")
    End Sub

    Private Sub SetTimer()
        ' Create a timer with a two second interval.
        aTimer = New System.Timers.Timer(2000)
        ' Hook up the Elapsed event for the timer. 
        AddHandler aTimer.Elapsed, AddressOf OnTimedEvent
        aTimer.AutoReset = True
        aTimer.Enabled = True
    End Sub

    ' The event handler for the Timer.Elapsed event. 
    Private Sub OnTimedEvent(source As Object, e As ElapsedEventArgs)
        Console.WriteLine("The Elapsed event was raised at {0:HH:mm:ss.fff}",
                          e.SignalTime)
    End Sub 
End Module
' The example displays output like the following:
'       Press the Enter key to exit the application...
'
'       The application started at 09:40:29.068
'       The Elapsed event was raised at 09:40:31.084
'       The Elapsed event was raised at 09:40:33.100
'       The Elapsed event was raised at 09:40:35.100
'       The Elapsed event was raised at 09:40:37.116
'       The Elapsed event was raised at 09:40:39.116
'       The Elapsed event was raised at 09:40:41.117
'       The Elapsed event was raised at 09:40:43.132
'       The Elapsed event was raised at 09:40:45.133
'       The Elapsed event was raised at 09:40:47.148
'
'       Terminating the application...

En el ejemplo de código siguiente se muestra una manera de evitar que el subproceso que llama al método continúe hasta que finalice un evento que se está ejecutando actualmente y también para evitar que dos eventos ejecuten el controlador de eventos al mismo tiempo (a menudo denominado Stop Elapsed Elapsed reenentrancy).

En el ejemplo se ejecutan 100 ejecuciones de prueba. Cada vez que se ejecuta la prueba, el temporizador se inicia con un intervalo de 150 milisegundos. El controlador de eventos usa el método para simular una tarea que varía aleatoriamente de Thread.Sleep 50 a 200 milisegundos de longitud. El método de prueba también inicia un subproceso de control que espera un segundo y, a continuación, detiene el temporizador. Si se controla un evento cuando el subproceso de control detiene el temporizador, el subproceso de control debe esperar hasta que finalice el evento antes de continuar.

La Interlocked.CompareExchange(Int32, Int32, Int32) sobrecarga del método se usa para evitar la reenlazancia y para evitar que el subproceso de control continúe hasta que finaliza un evento en ejecución. El controlador de eventos usa el método para establecer una variable de control en 1, pero solo si CompareExchange(Int32, Int32, Int32) el valor es actualmente cero. Se trata de una operación atómica. Si el valor devuelto es cero, la variable de control se ha establecido en 1 y el controlador de eventos continúa. Si el valor devuelto es distinto de cero, el evento simplemente se descarta para evitar la reenlazancia. (Si fuera necesario ejecutar cada evento, la Monitor clase sería una mejor manera de sincronizar los eventos). Cuando finaliza el controlador de eventos, vuelve a establecer la variable de control en cero. En el ejemplo se registra el número total de eventos que se ejecutaron, que se descartaron debido a la reenencia y que se produjeron después de llamar Stop al método .

El subproceso de control usa el método para establecer la variable de control en -1 (menos uno), pero solo si CompareExchange(Int32, Int32, Int32) el valor es actualmente cero. Si la operación atómica devuelve un valor distinto de cero, un evento se está ejecutando actualmente. El subproceso de control espera e intenta de nuevo. En el ejemplo se registra el número de veces que el subproceso de control tuvo que esperar a que finalizara un evento.

using System;
using System.Timers;
using System.Threading;

public class Test
{
    // Change these values to control the behavior of the program.
    private static int testRuns = 100;
    // Times are given in milliseconds:
    private static int testRunsFor = 500;
    private static int timerIntervalBase = 100;
    private static int timerIntervalDelta = 20;

    // Timers.
    private static System.Timers.Timer Timer1 = new System.Timers.Timer();
    private static System.Timers.Timer Timer2 = new System.Timers.Timer();
    private static System.Timers.Timer currentTimer = null;

    private static Random rand = new Random();

    // This is the synchronization point that prevents events
    // from running concurrently, and prevents the main thread
    // from executing code after the Stop method until any
    // event handlers are done executing.
    private static int syncPoint = 0;

    // Count the number of times the event handler is called,
    // is executed, is skipped, or is called after Stop.
    private static int numEvents = 0;
    private static int numExecuted = 0;
    private static int numSkipped = 0;
    private static int numLate = 0;

    // Count the number of times the thread that calls Stop
    // has to wait for an Elapsed event to finish.
    private static int numWaits = 0;

    [MTAThread]
    public static void Main()
    {
        Timer1.Elapsed += new ElapsedEventHandler(Timer1_ElapsedEventHandler);
        Timer2.Elapsed += new ElapsedEventHandler(Timer2_ElapsedEventHandler);

        Console.WriteLine();
        for(int i = 1; i <= testRuns; i++)
        {
            TestRun();
            Console.Write("\rTest {0}/{1}    ", i, testRuns);
        }

        Console.WriteLine("{0} test runs completed.", testRuns);
        Console.WriteLine("{0} events were raised.", numEvents);
        Console.WriteLine("{0} events executed.", numExecuted);
        Console.WriteLine("{0} events were skipped for concurrency.", numSkipped);
        Console.WriteLine("{0} events were skipped because they were late.", numLate);
        Console.WriteLine("Control thread waited {0} times for an event to complete.", numWaits);
    }

    public static void TestRun()
    {
        // Set syncPoint to zero before starting the test
        // run.
        syncPoint = 0;

        // Test runs alternate between Timer1 and Timer2, to avoid
        // race conditions between tests, or with very late events.
        if (currentTimer == Timer1)
            currentTimer = Timer2;
        else
            currentTimer = Timer1;

        currentTimer.Interval = timerIntervalBase
            - timerIntervalDelta + rand.Next(timerIntervalDelta * 2);
        currentTimer.Enabled = true;

        // Start the control thread that shuts off the timer.
        Thread t = new Thread(ControlThreadProc);
        t.Start();

        // Wait until the control thread is done before proceeding.
        // This keeps the test runs from overlapping.
        t.Join();
    }

    private static void ControlThreadProc()
    {
        // Allow the timer to run for a period of time, and then
        // stop it.
        Thread.Sleep(testRunsFor);
        currentTimer.Stop();

        // The 'counted' flag ensures that if this thread has
        // to wait for an event to finish, the wait only gets
        // counted once.
        bool counted = false;

        // Ensure that if an event is currently executing,
        // no further processing is done on this thread until
        // the event handler is finished. This is accomplished
        // by using CompareExchange to place -1 in syncPoint,
        // but only if syncPoint is currently zero (specified
        // by the third parameter of CompareExchange).
        // CompareExchange returns the original value that was
        // in syncPoint. If it was not zero, then there's an
        // event handler running, and it is necessary to try
        // again.
        while (Interlocked.CompareExchange(ref syncPoint, -1, 0) != 0)
        {
            // Give up the rest of this thread's current time
            // slice. This is a naive algorithm for yielding.
            Thread.Sleep(1);

            // Tally a wait, but don't count multiple calls to
            // Thread.Sleep.
            if (!counted)
            {
                numWaits += 1;
                counted = true;
            }
        }

        // Any processing done after this point does not conflict
        // with timer events. This is the purpose of the call to
        // CompareExchange. If the processing done here would not
        // cause a problem when run concurrently with timer events,
        // then there is no need for the extra synchronization.
    }

    // Event-handling methods for the Elapsed events of the two
    // timers.
    //
    private static void Timer1_ElapsedEventHandler(object sender,
        ElapsedEventArgs e)
    {
        HandleElapsed(sender, e);
    }

    private static void Timer2_ElapsedEventHandler(object sender,
        ElapsedEventArgs e)
    {
        HandleElapsed(sender, e);
    }

    private static void HandleElapsed(object sender, ElapsedEventArgs e)
    {
        numEvents += 1;

        // This example assumes that overlapping events can be
        // discarded. That is, if an Elapsed event is raised before
        // the previous event is finished processing, the second
        // event is ignored.
        //
        // CompareExchange is used to take control of syncPoint,
        // and to determine whether the attempt was successful.
        // CompareExchange attempts to put 1 into syncPoint, but
        // only if the current value of syncPoint is zero
        // (specified by the third parameter). If another thread
        // has set syncPoint to 1, or if the control thread has
        // set syncPoint to -1, the current event is skipped.
        // (Normally it would not be necessary to use a local
        // variable for the return value. A local variable is
        // used here to determine the reason the event was
        // skipped.)
        //
        int sync = Interlocked.CompareExchange(ref syncPoint, 1, 0);
        if (sync == 0)
        {
            // No other event was executing.
            // The event handler simulates an amount of work
            // lasting between 50 and 200 milliseconds, so that
            // some events will overlap.
            int delay = timerIntervalBase
                - timerIntervalDelta / 2 + rand.Next(timerIntervalDelta);
            Thread.Sleep(delay);
            numExecuted += 1;

            // Release control of syncPoint.
            syncPoint = 0;
        }
        else
        {
            if (sync == 1) { numSkipped += 1; } else { numLate += 1; }
        }
    }
}

/* On a dual-processor computer, this code example produces
   results similar to the following:

Test 100/100    100 test runs completed.
436 events were raised.
352 events executed.
84 events were skipped for concurrency.
0 events were skipped because they were late.
Control thread waited 77 times for an event to complete.
 */
Imports System.Timers
Imports System.Threading

Public Module Test
    
    ' Change these values to control the behavior of the program.
    Private testRuns As Integer = 100 
    ' Times are given in milliseconds:
    Private testRunsFor As Integer = 500
    Private timerIntervalBase As Integer = 100
    Private timerIntervalDelta As Integer = 20

    ' Timers.
    Private WithEvents Timer1 As New System.Timers.Timer
    Private WithEvents Timer2 As New System.Timers.Timer
    Private currentTimer As System.Timers.timer

    Private rand As New Random()

    ' This is the synchronization point that prevents events
    ' from running concurrently, and prevents the main thread 
    ' from executing code after the Stop method until any 
    ' event handlers are done executing.
    Private syncPoint As Integer = 0

    ' Count the number of times the event handler is called,
    ' is executed, is skipped, or is called after Stop.
    Private numEvents As Integer = 0
    Private numExecuted As Integer = 0
    Private numSkipped As Integer = 0
    Private numLate As Integer = 0

    ' Count the number of times the thread that calls Stop
    ' has to wait for an Elapsed event to finish.
    Private numWaits As Integer = 0

    <MTAThread> _
    Sub Main()
        Console.WriteLine()
        For i As Integer = 1 To testRuns
            TestRun
            Console.Write(vbCr & "Test {0}/{1}    ", i, testRuns)
        Next

        Console.WriteLine("{0} test runs completed.", testRuns)
        Console.WriteLine("{0} events were raised.", numEvents)
        Console.WriteLine("{0} events executed.", numExecuted)
        Console.WriteLine("{0} events were skipped for concurrency.", numSkipped)
        Console.WriteLine("{0} events were skipped because they were late.", numLate)
        Console.WriteLine("Control thread waited {0} times for an event to complete.", numWaits)
    End Sub

    Sub TestRun()
        ' Set syncPoint to zero before starting the test 
        ' run. 
        syncPoint = 0

        ' Test runs alternate between Timer1 and Timer2, to avoid
        ' race conditions between tests, or with very late events.
        If currentTimer Is Timer1 Then
            currentTimer = Timer2
        Else
            currentTimer = Timer1
        End If

        currentTimer.Interval = timerIntervalBase _
            - timerIntervalDelta + rand.Next(timerIntervalDelta * 2)
        currentTimer.Enabled = True

        ' Start the control thread that shuts off the timer.
        Dim t As New Thread(AddressOf ControlThreadProc)
        t.Start()

        ' Wait until the control thread is done before proceeding.
        ' This keeps the test runs from overlapping.
        t.Join()

    End Sub


    Private Sub ControlThreadProc()
        ' Allow the timer to run for a period of time, and then 
        ' stop it.
        Thread.Sleep(testRunsFor) 
        currentTimer.Stop

        ' The 'counted' flag ensures that if this thread has
        ' to wait for an event to finish, the wait only gets 
        ' counted once.
        Dim counted As Boolean = False

        ' Ensure that if an event is currently executing,
        ' no further processing is done on this thread until
        ' the event handler is finished. This is accomplished
        ' by using CompareExchange to place -1 in syncPoint,
        ' but only if syncPoint is currently zero (specified
        ' by the third parameter of CompareExchange). 
        ' CompareExchange returns the original value that was
        ' in syncPoint. If it was not zero, then there's an
        ' event handler running, and it is necessary to try
        ' again.
        While Interlocked.CompareExchange(syncPoint, -1, 0) <> 0 
            ' Give up the rest of this thread's current time
            ' slice. This is a naive algorithm for yielding.
            Thread.Sleep(1)

            ' Tally a wait, but don't count multiple calls to
            ' Thread.Sleep.
            If Not counted Then
                numWaits += 1
                counted = True
            End If
        End While

        ' Any processing done after this point does not conflict
        ' with timer events. This is the purpose of the call to
        ' CompareExchange. If the processing done here would not
        ' cause a problem when run concurrently with timer events,
        ' then there is no need for the extra synchronization.
    End Sub


    ' Event-handling methods for the Elapsed events of the two
    ' timers.
    '
    Private Sub Timer1_ElapsedEventHandler(ByVal sender As Object, _
        ByVal e As ElapsedEventArgs) Handles Timer1.Elapsed

        HandleElapsed(sender, e)
    End Sub

    Private Sub Timer2_ElapsedEventHandler(ByVal sender As Object, _
        ByVal e As ElapsedEventArgs) Handles Timer2.Elapsed

        HandleElapsed(sender, e)
    End Sub

    Private Sub HandleElapsed(ByVal sender As Object, ByVal e As ElapsedEventArgs)

        numEvents += 1

        ' This example assumes that overlapping events can be
        ' discarded. That is, if an Elapsed event is raised before 
        ' the previous event is finished processing, the second
        ' event is ignored. 
        '
        ' CompareExchange is used to take control of syncPoint, 
        ' and to determine whether the attempt was successful. 
        ' CompareExchange attempts to put 1 into syncPoint, but
        ' only if the current value of syncPoint is zero 
        ' (specified by the third parameter). If another thread
        ' has set syncPoint to 1, or if the control thread has
        ' set syncPoint to -1, the current event is skipped. 
        ' (Normally it would not be necessary to use a local 
        ' variable for the return value. A local variable is 
        ' used here to determine the reason the event was 
        ' skipped.)
        '
        Dim sync As Integer = Interlocked.CompareExchange(syncPoint, 1, 0)
        If sync = 0 Then
            ' No other event was executing.
            ' The event handler simulates an amount of work
            ' similar to the time between events, so that
            ' some events will overlap.
            Dim delay As Integer = timerIntervalBase _
                - timerIntervalDelta / 2 + rand.Next(timerIntervalDelta)
            Thread.Sleep(delay)
            numExecuted += 1

            ' Release control of syncPoint.
            syncPoint = 0
        Else
            If sync = 1 Then numSkipped += 1 Else numLate += 1
        End If
    End Sub 

End Module

' On a dual-processor computer, this code example produces
' results similar to the following:
'
'Test 100/100    100 test runs completed.
'436 events were raised.
'352 events executed.
'84 events were skipped for concurrency.
'0 events were skipped because they were late.
'Control thread waited 77 times for an event to complete.

Comentarios

También puede detener el tiempo estableciendo Enabled en false .

Nota

La señal para generar el evento siempre se pone en cola para su ejecución en un subproceso, por lo que el método de control de eventos puede ejecutarse en un subproceso al mismo tiempo que una llamada al método se ejecuta en Elapsed ThreadPool otro Stop subproceso. Esto podría provocar que Elapsed el evento se generara después de llamar Stop al método . El segundo ejemplo de código de la sección Ejemplos muestra una manera de evitar esta condición de carrera.

Se aplica a

Consulte también