I know it sounds stupid, but I've tried everything to stop a timer, but the timer won't stop. I'm working on a game and i would appreciate if someone could tell me how to stop a timer.
If you are using System.Timers.Timer stopping is performed by one of the options:
//options 1
timer.Enabled = false
//option 2
timer.Stop()
if you are using System.Threading.Timer, use this method
timer.Change(Timeout.Infinite , Timeout.Infinite)
if you are using System.Windows.Forms.Timer, use this method
timer.Stop();
So to add to the previous answers, in case you are using the System.Threading.Timer class,
this will stop it permanently with no further chance to use the same instance:
timer.Dispose()
otherwise:
timer.Change(Timeout.Infinite, Timeout.Infinite)
System.Windows.Forms.Timer: timer.Enabled = false;
System.Threading.Timer: timer.Change(Timeout.Infinite, Timeout.Infinite);
System.Timers.Timer: timer.Enabled = false; or timer.Stop();
With each of the timers in the .NET framework, it's possible that the timer fires just before you stop it, so you'll see the callback after you stop it.
You'll need to use something like an asynchronous callback context: use a bool set to true when you want the timer running, and set it to false when you stop it. Then have your callback check your context to see if it should really run or not.
Assuming you are making use of the System.Windows.Forms.Timer; since there was no explicit reference to anything else...if that is the case...
System.Windows.Forms.Timer myTimer = new System.Windows.Forms.Timer();
myTimer.Stop();
Depends on the timer. If it is from threading namespace, dispose of it and recreate it when you need to, or have your timer delegate wait on reset event(see msdn). System.Timers namespace has a start and stop method.
I also ran into the similar problem many times.
//Timer init.
var _timer = new System.Timers.Timer
{
AutoReset = true,
Enabled = true,
Interval = TimeSpan.FromSeconds(15).TotalMilliseconds //15 seconds interval
};
_timer.Elapsed += DoSomethingOnTimerElapsed;
//To be called on timer elapsed.
private void DoSomethingOnTimerElapsed(object source, ElapsedEventArgs e)
{
//Disable timer.
_timer.Enabled = false; //or _timer.Stop()
try
{
//does long running process
}
catch (Exception ex)
{
}
finally
{
if (_shouldEnableTimer) //set its default value to true.
_timer.Enabled = true; //or _timer.Start()
}
}
//somewhere in the code if you want to stop timer:
_timer.Enabled = _shouldEnableTimer = false;
//At any point, if you want to resume timer add this:
_timer.Enabled = _shouldEnableTimer = true;
Why to do so?
Lets assume, the code inside the try block takes more time. So, by the time you disable timer (_timer.Enabled = false or _timer.Stop()), there is high possibilty that the code inside try block is still executing. Hence, after completion of the task when it comes to finally, it is again enabled if there is no flag(_shouldEnableTimer) check. Therefore, I prevent your problem by adding an additional flag check.
For more clarity, please go through the code and the added comments. Hope this helps.
Related
I want to execute a function every 60 seconds in C#. I could use the Timer class like so:
timer1 = new Timer();
timer1.Tick += new EventHandler(timer1_Tick);
timer1.Interval = 60 * 1000; // in miliseconds
timer1.Start();
Question is I have a long running process. Occasionally it make take several minutes. Is there a way to make the timer smart so if the function is already being executed then it should skip that cycle and come back 60 seconds later and if again it is in execution then again skip and come back 60 seconds later.
I would suggest you to have a class member variable bool variable with value false.
then in click event return if its true at the beginning.
and then set it to true, so that it will tell you that its currently in execution.
then write your logic.
and then once done finally set it to false again.
code will look like this.
private bool isRunning = false;
private void timer1_Tick(object sender, EventArgs e)
{
if (isRunning)
{
return;
}
isRunning = true;
try
{
... //Do whatever you want
}
finally
{
isRunning = false;
}
}
The modern and most clean way to do this is using Microsoft's new Period Timer:
var timer = new PeriodicTimer(TimeSpan.FromSeconds(n));
while (await timer.WaitForNextTickAsync())
{
//Business logic
}
If you need to abort such a ticker, you can pass a cancellation token to the WaitForNextTickAsync method.
Another advantage is this:
The PeriodicTimer behaves like an auto-reset event, in that multiple ticks are coalesced into a single tick if they occur between calls to WaitForNextTickAsync(CancellationToken). Similarly, a call to Dispose() will void any tick not yet consumed. WaitForNextTickAsync(CancellationToken) may only be used by one consumer at a time, and may be used concurrently with a single call to Dispose().
Source: https://learn.microsoft.com/en-us/dotnet/api/system.threading.periodictimer.waitfornexttickasync?source=recommendations&view=net-7.0#remarks
If you need more granularity (like "always at 10 am", use something like https://github.com/HangfireIO/Cronos
Use a timer, set it to 60 second
On Event:
try
Stop timer
Do logic
catch
What ever fail recovery
finally
Start the timer
Logic is run 60 seconds after last finish.
You can use a Stopwatch inside a loop: start the stopwatch, after 60 second call the function, reset the stopwatch, start the loop again.
I have this code:
private void Form1_Load(object sender, EventArgs e)
{
/*start update timer*/
System.Timers.Timer updateticker = new System.Timers.Timer();
updateticker.Elapsed += new ElapsedEventHandler(update_overload);
//10 minute ticker
updateticker.Interval = 600000;
//30 sec ticker
updateticker.Interval = 30000;
updateticker.Enabled = true;
System.Timers.Timer guiTimer = new System.Timers.Timer();
guiTimer.Elapsed += new ElapsedEventHandler(idle_display);
//1 minute ticker
guiTimer.Interval = 60000;
//30 sec ticker
//updateticker.Interval = 30000;
guiTimer.Enabled = true;
}
//run front end idle timer
public void idle_display(object source, ElapsedEventArgs e)
{
if (minutes_left > 0) {
minutes_left = minutes_left - 1;
}
lbl_dyn_status.Text = "Time until next automatic update: "+ minutes_left + " minutes.";
}
Visual studio is flagging the final line of the second function as unsafe cross threading. Can anyone suggest how I rewrite this to solve the issue?
Cheers
Use System.Windows.Forms.Timer instead of System.Timers.Timer
or use SynchronizingObject property of Timer.
When SynchronizingObject is null, the method that handles the Elapsed event is called on a thread from the system-thread pool. For more information on system-thread pools, see ThreadPool.
When the Elapsed event is handled by a visual Windows Forms component, such as a button, accessing the component through the system-thread pool might result in an exception or just might not work. Avoid this effect by setting SynchronizingObject to a Windows Forms component, which causes the method that handles the Elapsed event to be called on the same thread that the component was created on.
As others suggested, use System.Windows.Forms.Timer. Unlike System.Threading.Timer, which operates on Thread Pool threads, it guarantees you that the tick event is invoked on the UI thread.
The UI thread is the only thread allows to modify the UI. This is why you get an exception trying to write lbl_dyn_status.Text.
Use System.Windows.Forms.Timer timer instead of System.Timers.Timer.
Change the handler to
public void IdleDisplay(object source, ElapsedEventArgs e)
{
if (lbl_dyn_status.InvokeRequired)
{
this.Invoke(IdleDisplay)
}
else
{
if (minutes_left > 0)
{
minutes_left = minutes_left - 1;
}
lbl_dyn_status.Text = string.Format(
"Time until next automatic update: {0} minutes.",
minutes_left);
}
}
This way allows you to use the thread free System.Threading.Timer but checks for a cross-thread call in the handler. If detected the call is invoked on the main GUI thread, via the Form class.
This is described on MSDN in more detail here.
More generally, you should not use timers to count time like this. The more thread bound your timer is, the more it is likely to diverge from real elapsed time. You can use your timer to schedule an update of your clock but, you should calculate elapsed time since some fixed point rather than using an iterative counter.
I have a method that I want to call a method (will mention as myFanc) in seperated thread every 3 seconds
The code below can easly do it,
Timer myTimer = new Timer();
myTimer.Elapsed += new ElapsedEventHandler( myFanc );
myTimer.Interval = 3000;
myTimer.Start();
The code above may cause myFanc to be called while another call to myFanc isn't finished yet
My problem is that I also want myFanc to finished before I will call her agian, so basically I want to call the method in seperated thread every 3 seconds after myFanc is finished, how can I do it?
I don't mind if the solution won't use Timer class, I just want this behavior to work..
Set the AutoReset property of your timer to false, then, at the end of your event handler (i.e. "myFanc"), call the Start method of your timer again.
Do not use a timer, loop in the thread calling "myfanc" and use
Thread.Sleep(3000);
to insert the desired delay.
At the top of myFunc put this
myTimer.Enabled = false;
and at the end when it is finished put this
myTimer.Enabled = true;
It will cause that you will temporairly disable the Timer while function is executing
This is the solution I used - thanks to Jim
using System;
using System.Timers;
using System.Threading;
class myApp
{
public static void Main()
{
System.Timers.Timer myTimer = new System.Timers.Timer();
myTimer.Elapsed += new ElapsedEventHandler( myFanc );
myTimer.Interval = 1000;
myTimer.AutoReset = false;
myTimer.Start();
while ( Console.Read() != 'q' )
{
; // do nothing...
}
}
public static void myFanc(object source, ElapsedEventArgs e)
{
Console.Write("\r{0}", DateTime.Now);
Thread.Sleep(3000); //the sleep here is just to test the method, wait to be finished before another call the myFanc method is being performed
System.Timers.Timer myTimer = new System.Timers.Timer();
myTimer.Elapsed += new ElapsedEventHandler(myFanc);
myTimer.Interval = 1000;
myTimer.AutoReset = false;
myTimer.Start();
}
}
2 methods than I can think of right now
Stop and start the timer inside the myFanc method This ensures 3 seconds between each run
Wrap your code in myFanc inside a lock, this will just skip a turn if it's not finished.
Make sure you use the correct timer.. system.threading.timer is a seperate thread. The timer class in windows.forms (or something like that) isn't
Use a thread and Thread.Sleep(x) like so
Thread thread = new Thread(new ThreadStart(myTimer));
thread.Start();
void myTimer()
{
while (!exit)
{
myFunc();
Thread.Sleep(3000);
}
}
Can i create successfully a timer clock on a thread? i'm creating one but it doesn't seem to work that well. My app is a multi-thread app that has to start a timer on a thread when ever a certain event happens. The timer is placed in every client connection. The clock doesn't work until i close my winform(i don't know why) . Is there anything in particular that i should know about timers in threads ?
Here is my timer code :
timer1.Interval = 1000;
timer1.Tick += new EventHandler(timer_Tick);
timer1.Enabled = true;
timer1.Start();
You might try to use System.Threading.Timer, which is basically a timer that's in a separate thread. You might also consider using a WaitHandle that's never fired and then using WaitOne(1000, false) to wait for a second.
Try this:
public void EnableTimer()
{
if (this.InvokeRequired)
this.Invoke(new Action(EnableTimer));
else
this.timer1.Enabled = true;
}
There are three Timer classes that I am aware of, System.Threading.Timer, System.Timers.Timer, and System.Windows.Forms.Timer, but none of these have a .Reset() function which would reset the current elapsed time to 0.
Is there a BCL class that has this functionality? Is there a non-hack way of doing it? (I thought perhaps changing the time limit on it might reset it) Thought on how hard it would be to reimplement a Timer class that had this functionality, or how to do it reliably with one of the BCL classes?
I always do ...
myTimer.Stop();
myTimer.Start();
... is that a hack? :)
Per comment, on Threading.Timer, it's the Change method ...
dueTime Type: System.Int32 The
amount of time to delay before the
invoking the callback method specified
when the Timer was constructed, in
milliseconds. Specify
Timeout.Infinite to prevent the
timer from restarting. Specify zero
(0) to restart the timer immediately.
All the timers have the equivalent of Start() and Stop() methods, except System.Threading.Timer.
So an extension method such as...
public static void Reset(this Timer timer)
{
timer.Stop();
timer.Start();
}
...is one way to go about it.
For System.Timers.Timer, according to MSDN documentation, http://msdn.microsoft.com/en-us/library/system.timers.timer.enabled.aspx:
If the interval is set after the Timer has started, the count is
reset. For example, if you set the interval to 5 seconds and then set
the Enabled property to true, the count starts at the time Enabled is
set. If you reset the interval to 10 seconds when count is 3 seconds,
the Elapsed event is raised for the first time 13 seconds after
Enabled was set to true.
So,
const double TIMEOUT = 5000; // milliseconds
aTimer = new System.Timers.Timer(TIMEOUT);
aTimer.Start(); // timer start running
:
:
aTimer.Interval = TIMEOUT; // restart the timer
You could write an extension method called Reset(), which
calls Stop()-Start() for Timers.Timer and Forms.Timer
calls Change for Threading.Timer
I just assigned a new value to the timer:
mytimer.Change(10000, 0); // reset to 10 seconds
It works fine for me.
at the top of the code define the timer: System.Threading.Timer myTimer;
if (!active)
myTimer = new Timer(new TimerCallback(TimerProc));
myTimer.Change(10000, 0);
active = true;
private void TimerProc(object state)
{
// The state object is the Timer object.
var t = (Timer)state;
t.Dispose();
Console.WriteLine("The timer callback executes.");
active = false;
// Action to do when timer is back to zero
}
For a Timer (System.Windows.Forms.Timer).
The .Stop, then .Start methods worked as a reset.
You can do timer.Interval = timer.Interval
I do the following.
Disposing the timer and initializing it again.
But this will erase any event you attached to this timer.
timer.Dispose();
timer = new System.Timers.Timer();
Other alternative way to reset the windows.timer is using the counter, as follows:
int timerCtr = 0;
Timer mTimer;
private void ResetTimer() => timerCtr = 0;
private void mTimer_Tick()
{
timerCtr++;
// Perform task
}
So if you intend to repeat every 1 second, you can set the timer interval at 100ms, and test the counter to 10 cycles.
This is suitable if the timer should wait for some processes those may be ended at the different time span.
i do this
//Restart the timer
queueTimer.Enabled = true;