Timer.Stop Methode
Definition
Wichtig
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public:
void Stop();
public void Stop ();
member this.Stop : unit -> unit
Public Sub Stop ()
Beispiele
Im folgenden Beispiel wird ein System.Timers.Timer
-Objekt instanziiert, das sein Timer.Elapsed Ereignis alle zwei Sekunden (2.000 Millisekunden) auslöst, einen Ereignishandler für das Ereignis einrichtet und den Timer startet. Der Ereignishandler zeigt den Wert der ElapsedEventArgs.SignalTime-Eigenschaft bei jedem Auslösen an. Wenn der Benutzer die EINGABETASTE drückt, ruft die Anwendung die Stop -Methode auf, bevor die Anwendung beendet wird.
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...
open System
open System.Timers
let onTimedEvent source (e: ElapsedEventArgs) =
printfn $"""The Elapsed event was raised at {e.SignalTime.ToString "HH:mm:ss.fff"}"""
// Create a timer with a two second interval.
let aTimer = new Timer 2000
// Hook up the Elapsed event for the timer.
aTimer.Elapsed.AddHandler onTimedEvent
aTimer.AutoReset <- true
aTimer.Enabled <- true
printfn "\nPress the Enter key to exit the application...\n"
printfn $"""The application started at {DateTime.Now.ToString "HH:mm:ss.fff"}"""
stdin.ReadLine() |> ignore
aTimer.Stop()
aTimer.Dispose()
printfn "Terminating the application..."
// 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...
Das folgende Codebeispiel zeigt eine Möglichkeit, um zu verhindern, dass der Thread, der die Stop -Methode aufruft, bis ein aktuell ausgeführtes Elapsed Ereignis endet, fortgesetzt wird, und auch, um zu verhindern, dass zwei Elapsed Ereignisse den Ereignishandler gleichzeitig ausführen (oft auch als Reentranz bezeichnet).
Im Beispiel werden 100 Testläufe ausgeführt. Bei jeder Testausführung wird der Timer mit einem Intervall von 150 Millisekunden gestartet. Der Ereignishandler verwendet die Thread.Sleep -Methode, um eine Aufgabe zu simulieren, die zufällig in der Länge von 50 bis 200 Millisekunden variiert. Die Testmethode startet auch einen Steuerelementthread, der eine Sekunde wartet und dann den Timer beendet. Wenn ein Ereignis behandelt wird, wenn der Steuerungsthread den Timer beendet, muss der Steuerelementthread warten, bis das Ereignis abgeschlossen ist, bevor er fortfahren kann.
Die Interlocked.CompareExchange(Int32, Int32, Int32) Methodenüberladung wird verwendet, um eine erneute Internetverbindung zu vermeiden und zu verhindern, dass der Kontrollthread fortgesetzt wird, bis ein ausgeführtes Ereignis endet. Der Ereignishandler verwendet die CompareExchange(Int32, Int32, Int32) -Methode, um eine Steuerelementvariable auf 1 festzulegen, aber nur, wenn der Wert derzeit null ist. Dies ist ein atomischer Vorgang. Wenn der Rückgabewert null ist, wurde die Steuerelementvariable auf 1 festgelegt, und der Ereignishandler wird fortgesetzt. Wenn der Rückgabewert ungleich 0 (null) ist, wird das Ereignis einfach verworfen, um eine erneute Anfälligkeit zu vermeiden. (Wenn es erforderlich wäre, jedes Ereignis auszuführen, wäre die Monitor -Klasse eine bessere Möglichkeit, die Ereignisse zu synchronisieren.) Wenn der Ereignishandler endet, wird die Steuerelementvariable wieder auf 0 (null) festgelegt. Im Beispiel wird die Gesamtanzahl der ausgeführten Ereignisse aufgezeichnet, die aufgrund einer erneuten Anfälligkeit verworfen wurden und die nach dem Aufruf der Stop -Methode aufgetreten sind.
Der Steuerungsthread verwendet die CompareExchange(Int32, Int32, Int32) -Methode, um die Steuerelementvariable auf -1 (minus 1) festzulegen, aber nur, wenn der Wert derzeit null ist. Wenn der atomische Vorgang ungleich 0 (null) zurückgibt, wird derzeit ein Ereignis ausgeführt. Der Steuerelementthread wartet und versucht es erneut. Im Beispiel wird aufgezeichnet, wie oft der Steuerungsthread auf das Beenden eines Ereignisses warten musste.
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.
*/
open System
open System.Threading
// Change these values to control the behavior of the program.
let testRuns = 100
// Times are given in milliseconds:
let testRunsFor = 500
let timerIntervalBase = 100
let timerIntervalDelta = 20
// Timers.
let timer1 = new Timers.Timer()
let timer2 = new Timers.Timer()
let mutable currentTimer = Unchecked.defaultof<Timers.Timer>
let rand = 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.
let mutable syncPoint = 0
// Count the number of times the event handler is called,
// is executed, is skipped, or is called after Stop.
let mutable numEvents = 0
let mutable numExecuted = 0
let mutable numSkipped = 0
let mutable numLate = 0
// Count the number of times the thread that calls Stop
// has to wait for an Elapsed event to finish.
let mutable numWaits = 0
let 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.
let mutable 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(&syncPoint, -1, 0) <> 0 do
// 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 <- 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.
let 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 then
currentTimer <- timer2
else
currentTimer <- timer1
currentTimer.Interval <-
timerIntervalBase - timerIntervalDelta + (timerIntervalDelta * 2 |> rand.Next)
|> float
currentTimer.Enabled <- true
// Start the control thread that shuts off the timer.
let t = new Thread(ThreadStart controlThreadProc)
t.Start()
// Wait until the control thread is done before proceeding.
// This keeps the test runs from overlapping.
t.Join()
let handleElapsed sender e =
numEvents <- 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.)
//
let sync = Interlocked.CompareExchange(&syncPoint, 1, 0)
if sync = 0 then
// 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.
timerIntervalBase - timerIntervalDelta / 2 + rand.Next timerIntervalDelta
|> Thread.Sleep
numExecuted <- numExecuted + 1
// Release control of syncPoint.
syncPoint <- 0
else if sync = 1 then
numSkipped <- numSkipped + 1
else
numLate <- numLate + 1
// Event-handling methods for the Elapsed events of the two
// timers.
let timer1_ElapsedEventHandler = handleElapsed
let timer2_ElapsedEventHandler = handleElapsed
[<EntryPoint; MTAThread>]
let main _ =
timer1.Elapsed.AddHandler timer1_ElapsedEventHandler
timer2.Elapsed.AddHandler timer2_ElapsedEventHandler
printfn ""
for i = 1 to testRuns do
testRun ()
printf $"\rTest {i}/{testRuns} "
printfn $"{testRuns} test runs completed."
printfn $"{numEvents} events were raised."
printfn $"{numExecuted} events executed."
printfn $"{numSkipped} events were skipped for concurrency."
printfn $"{numLate} events were skipped because they were late."
printfn $"Control thread waited {numWaits} times for an event to complete."
0
// 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.
Hinweise
Sie können die Zeitsteuerung auch beenden, indem Sie auf false
festlegenEnabled.
Hinweis
Das Signal zum Auslösen des Ereignisses wird immer für die Elapsed Ausführung in einem ThreadPool Thread in die Warteschlange eingereiht, sodass die Ereignisbehandlungsmethode in einem Thread ausgeführt werden kann, während ein Aufruf der Stop -Methode in einem anderen Thread ausgeführt wird. Dies kann dazu führen, dass das Elapsed Ereignis ausgelöst wird, nachdem die Stop -Methode aufgerufen wurde. Das zweite Codebeispiel im Abschnitt Beispiele zeigt eine Möglichkeit, diese Racebedingung zu umgehen.