How do I wait for a specified time while showing the remaining time to wait?
I now solved it like this but I feel like this is a really bad way to do it:
//This is running in a BackgroundWorker:
Stopwatch watch = new Stopwatch();
watch.Start();
while(watch.ElapsedMilliseconds != SecondsToWait * 1000)
{
TimeToNextRefresh = ((SecondsToWait * 1000) - watch.ElapsedMilliseconds) / 1000;
Thread.Sleep(1);
}
watch.Stop();
So here I am guessing that the condition (watch.ElapsedMilliseconds != SecondsToWait * 1000) is checked every millisecond.
So the main question is; In what period is the condition of while checked and/or how do I improve the code I've written?
It depends on what's the code inside while loop!
For example, if you write some really long/time-consuming code in a while loop, each iteration of the while loop, or course, will be longer than a while loop that only has short/fast code.
Compare these two while loops:
while (true) {
Console.WriteLine("Hello");
}
and
while (true) {
Console.Beep(5000);
}
Each iteration of the first while loop is faster than that of the second one because Console.Beep(5000) takes 5 seconds and Console.WriteLine only takes a fraction of a second.
So you can't rely on while loops to count time.
This is what you should do:
Create an instance of System.Windows.Forms.Timer, not the System.Timers.Timer nor the System.Threading.Timer. I find the first one the most useful (others are more advanced).
Timer timer = new Timer();
timer.Interval = 1000; // 1000 means 1000ms aka 1 second
timer.Tick += TimerTicked;
timer.Start();
Now the compiler will tell you that TimerTicked is not defined, so let's go define that:
private void TimerTicked(object sender, EventArgs e) {
}
Now you're all set. The code in TimerTicked will be called every one second.
Let's say you want to measure a time of 10 seconds. After 10 seconds, you want to do something. So first create a variable called secondsLeft in the class level:
int secondsLeft = 10;
Now in TimerTicked, you want to check whether secondsLeft is 0. If it is, do that something, else, minus one:
if (secondsLeft == 0) {
DoSomething();
} else {
secondsLeft--;
}
And secondsLeft is the time remaining! You can display it on a label or something.
To pause the timer, simply
timer.Stop();
The exact interval in which your while condition is checked is hard to predict. Thread.Sleep(1); only tells the operating system that you want your thread to sleep for at least 1 millisecond. There is no guarantee that your thread will be active again after exactly 1ms. Actually you can rather be sure that it will be more than that. The thread is scheduled again after 1ms, but there will be a delay until he gets his CPU time slot.
The interval you want for your loop actually depends how you want to display the remaining time. If you want to display only seconds, why would you update that display every millisecond, although the text would change only every 1000ms?
A loop like that is probably not a good way to implement something like that. I would recommend a System.Threading.Timer:
// this Timer will call TimerTick every 1000ms
Timer timer = new Timer(TimerTick, null, 0, 1000);
and implement the handler
public void TimerTick(object sender)
{
// update your display
}
Note that you will have the "update your display" part on the UI thread again, as this method is called by the Timer on a different thread.
This code is can really make an infinite loop if a calculation just take longer than 1 miliseconds.
You can achieve your desired behaviour with a simple System.Winforms.Forms.Timer like this snipped below :
private int tickCount = 0;
private int remaining = 10;
private void timer1_Tick(object sender, EventArgs e)
{
remaining--;
textBox1.Text = remaining.ToString();
}
private void Form1_Load(object sender, EventArgs e)
{
timer1.Interval = 1000;
timer1.Enabled = true;
}
With this you can countdown from 10 seconds and every tick you write to a textbox the remaining seconds
Related
I have a c# windows service with a timer that executes a process every 5 minutes.
I don't want to create other process to execute a task every 30 minutes, so is it possible within the same timer timer_Elapsed event to do that logic? any clue?
Thanks a lot,
How about using 2 timers?
You could increment a variable every time the timer elapses, and when that variable reaches 6, you reset it to 0 and execute your 'once every 30 minute' code. Also, creating a new (winform) timer does not create a new thread as far as I know.
int TimerVariable=0;
TimerEvent(object sender,eventargs e)
{
TimerVariable++;
if(TimverVariable>=6)
{
//Execute the once every 30 min code
}
//Execute the once every 5 min code.
}
Well, you could just use a counter and check it against 6(30000/5000) and reset it back to zero when done.
private int counter = 0;
private void TimerCallback()
{
counter++;
if(counter >=6)
{
//Your 30 seconds code here
counter = 0;
}
}
I have an application that generates random numbers for about 20 seconds and shows the random number on the fly in a label in the screen.
I want to show the numbers in the same label but then slow down the display of the numbers so like 5 seconds before stoping the process, the display of the number should smoothly slow down more and more until it stops in the final number. Like a raffle.
Any clue?
I can start by telling you what not do to. Do not use Thread.Sleep -- doing so is almost always a "worst practice" and will make your UI unresponsive.
If you use Thread.Sleep on a second thread, as mcl suggests, you won't freeze your UI but you are burning an extremely expensive thread to do very little work.
If you are using C# 4 or earlier then I would create a timer set to tick, say, four times a second. Handle the tick event, and if enough time has passed since the last tick event, change the label. Or, change the interval of the timer each time it ticks.
If you are using C# 5, you can just use await Task.Delay(x):
async void Animate()
{
int delay = 5;
for(int i = 1; i < 10; ++i)
{
UpdateLabel();
await Task.Delay(delay);
delay = delay * 2;
}
}
So now you start with a 5ms delay, then 10, then 20...
Here's a working program to get you started. It changes the Text of the Form for 3 seconds quickly, after which it gets slower. That's achieved by using one Timer to start decelerating the Timer which shows the random numbers.
public partial class Form1 : Form
{
System.Windows.Forms.Timer timer = new System.Windows.Forms.Timer() { Interval = 10 };
System.Windows.Forms.Timer timerForStartingSlowDown = new System.Windows.Forms.Timer() { Interval = 3000 };
bool slow = false;
Random random = new Random();
public Form1()
{
InitializeComponent();
timer.Tick += timer_Tick;
timerForStartingSlowDown.Tick += timerForStartingSlowDown_Tick;
Shown += Form1_Shown;
}
void timerForStartingSlowDown_Tick(object sender, EventArgs e)
{
slow = true;
timerForStartingSlowDown.Enabled = false;
}
void Form1_Shown(object sender, EventArgs e)
{
timer.Enabled = true;
timerForStartingSlowDown.Enabled = true;
}
void timer_Tick(object sender, EventArgs e)
{
if (timer.Interval > 350) timer.Enabled = false;
else
{
if (slow) timer.Interval += 10;
Text = random.Next(1, 100).ToString();
}
}
}
Consider generating those numbers on a different thread. You can use BackgroundWorker for that and report the progress as you generate each number. When you begin to reach the end use Thread.Sleep(miliseconds) to "slow" (freez) the BackgroundWorker's job thread that is generating the numbers for a specified amount of miliseconds increasing those miliseconds as you aproach the final number. That should do the trick.
http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx
Set the BackgroundWorker to report progress and use that to "push" the generated number to the UI thread.
You can also drag and drop the BackgroundWorker component on your form from the Toolbox.
For example, I have set timer1.Interval to 5000 and I would like to know how much of this interval remains before the timer ticks. How I can do it?
How to check timer time?
You cannot. The timer classes offer no way check how long remains before a timer is due to fire. The best you can do is to keep track of when the timer last fired and calculate yourself how long remains before the next tick.
DateTime MainTimer_last_Tick = DateTime.Now;
System.Windows.Forms.Timer timer_Calc_Remaining;
timer_Calc_Remaining.Enabled = true;
timer_Calc_Remaining.Interval = 100;
timer_Calc_Remaining.Tick += new System.EventHandler(this.timer_Calc_Remaining_Tick);
on main timer start or tick:
timer_Main.Enabled = true;
MainTimer_last_Tick = DateTime.Now;
private void timer_Calc_Remaining_Tick(object sender, EventArgs e)
{
int remaining_Milliseconds = (int)(MainTimer_last_Tick.AddMilliseconds(timer_Main.Interval).Subtract(DateTime.Now).TotalMilliseconds);
.../*
int newValue = (timer_Main.Interval -remaining_Milliseconds) ;
progressBar1.Maximum = timer_Main.Interval+1;
progressBar1.Value = newValue ;*/
}
You could use an alternative timer with an interval of 1000 (milliseconds). I don't think an interval of 1ms is really an option as this will stress the system too much and is unreliable anyway.
Every time this timer elapses, you can check the number of ticks (is this always a multitude of 1000?) and subtract it from (or use modulo) 5000.
But I can't:
That's because less than sign comes before equal sign and not the other way round
Its <= not =<
if (timer1.Interval <= 5000)
{
//do something
}
You are using the Interval which is a property that will not be getting changed (It will always be 5000, so checking if it is smaller than 5000 is pointless). Also, if this code is in the Timer1_Tick function it will not be efficient. However, the code I believe you need is:
if (timer1.Interval <= 5000)
{
//do something
}
I have an app that I would like to update on an interval. I am looking for maybe some type of if statement or try - catch statement. I already have a foreach statement in the same class, but i dont think I can put in there? I would also like to set it up so that the user can change the refresh rate. Any help is appreciated. Thanks
Here is the method that I would like to put the timer in...
private void _UpdatePortStatus(string[] files)
{
foreach (string file in files)
{
PortStatus ps = new PortStatus();
ps.ReadXml(new StreamReader(file));
if (!_dicPortStatus.ContainsKey(ps.General[0].Group))
{
_dicPortStatus.Add(ps.General[0].Group, ps);
}
PortStatus psOrig = _dicPortStatus[ps.General[0].Group];
foreach (PortStatus.PortstatusRow psr in ps.Portstatus.Rows)
{
DataRow[] drs = psOrig.Portstatus.Select("PortNumber = '" + psr.PortNumber + "'");
if (drs.Length == 1)
{
DateTime curDt = DateTime.Parse(drs[0]["LastUpdateDateTimeUTC"].ToString());
DateTime newDt = psr.LastUpdateDateTimeUTC;
if (newDt > curDt)
{
drs[0]["LastUpdateDateTimeUTC"] = newDt;
}
}
else if (drs.Length == 0)
{
psOrig.Portstatus.ImportRow(psr);
}
else
{
throw new Exception("More than one of the same portnumber on PortStatus file: " + file);
}
}
}
}
Look at the System.Timer class. You basically set an interval (eg. 10000 milliseconds) and it will raise an event every time that interval time passes.
To allow the use to change the refresh rate, write a method that receives input from the user and use that to update the TimerInterval. Note that the TimerInterval is in miliseconds, so you may need to convert to that from whatever the user input.
So, from the example, the event will be raised every 10 seconds:
System.Timers.Timer aTimer = new System.Timers.Timer(10000); //10 seconds
// Hook up the Elapsed event for the timer.
aTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
aTimer.Enabled = true; // Starts the Timer
// Specify what you want to happen when the Elapsed event is raised
private static void OnTimedEvent(object source, ElapsedEventArgs e)
{
//Perform update
_UpdatePortStatus(files);
}
UPDATE: In response to your posted code, it appears you simply want to call _UpdatePortStatus to update the port status at regular intervals (see the updated example above).
One important point you need to bear in mind though is that the Timer will run on a separate thread, and as such could raise the event again before it has finished running from the last time if it takes more than the interval time to run.
Use System.Timers.Timer, System.Threading.Timer or System.Windows.Forms.Timer ... depending on what exactly it is that you "would like to update on an interval."
See the following articles:
http://www.intellitechture.com/System-Windows-Forms-Timer-vs-System-Threading-Timer-vs-System-Timers-Timer/
http://www.yoda.arachsys.com/csharp/threads/timers.shtml
Your question is somewhat vague as there an many different methods of achieving what you want to do. However in the simplest terms you need to create a System.Threading.Timer that ticks on whatever frequency you define, for example:
private System.Threading.Timer myTimer;
private void StartTimer()
{
myTimer = new System.Threading.Timer(TimerTick, null, 0, 5000);
}
private void TimerTick(object state)
{
Console.WriteLine("Tick");
}
In this example the timer will 'tick' every 5 seconds and perform whatever functionality you code into the TimerTick method. If the user wants to change the frequency then you would destroy the current timer and initialise with the new frequency.
All this said, I must stress that this is the simplest of implementation and may not suit your needs.
I want to do stuff every minute on the minute (by the clock) in a windows forms app using c#. I'm just wondering whats the best way to go about it ?
I could use a timer and set its interval to 60000, but to get it to run on the minute, I would have to enable it on the minute precisely, not really viable.
I could use a timer and set its interval to 1000. Then within its tick event, I could check the clocks current minute against a variable that I set, if the minute has changed then run my code. This worries me because I am making my computer do a check every 1 second in order to carry out work every 1 minutes. Surely this is ugly ?
I'm using windows forms and .Net 2.0 so do not want to use the DispatchTimer that comes with .Net 3.5
This must be a fairly common problem. Have any of you a better way to do this?
Building on the answer from aquinas which can drift and which doesn't tick exactly on the minute just within one second of the minute:
static System.Timers.Timer t;
static void Main(string[] args)
{
t = new System.Timers.Timer();
t.AutoReset = false;
t.Elapsed += new System.Timers.ElapsedEventHandler(t_Elapsed);
t.Interval = GetInterval();
t.Start();
Console.ReadLine();
}
static double GetInterval()
{
DateTime now = DateTime.Now;
return ((60 - now.Second) * 1000 - now.Millisecond);
}
static void t_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
Console.WriteLine(DateTime.Now.ToString("o"));
t.Interval = GetInterval();
t.Start();
}
On my box this code ticks consistently within .02s of each minute:
2010-01-15T16:42:00.0040001-05:00
2010-01-15T16:43:00.0014318-05:00
2010-01-15T16:44:00.0128643-05:00
2010-01-15T16:45:00.0132961-05:00
How about:
int startin = 60 - DateTime.Now.Second;
var t = new System.Threading.Timer(o => Console.WriteLine("Hello"),
null, startin * 1000, 60000);
Creating a Timer control that fires every 1 second (and usually does nothing but a simple check) will add negligible overhead to your application.
Simply compare the value of Environment.TickCount or DateTime.Now to the last stored time (the previous 'minute tick'), and you should have a reasonably precise solution. The resolution of these two time values is about 15ms, which should be sufficient for your purposes.
Do note however that the interval of the Timer control is not guaranteed to be that precise or even anywhere now, since it runs on the Windows message loop, which is tied in with the responsiveness of the UI. Never rely on it for even moderately precise timing - though it is good enough for firing repeating events where you can check the time using a more sensitive method such as one of the two given above.
You can nail this with reactive extensions which will take care of lots of timer related problems for you (clock changes, app hibernation etc). Use Nuget package Rx-Main and code like this:
Action work = () => Console.WriteLine(DateTime.Now.ToLongTimeString());
Scheduler.Default.Schedule(
// start in so many seconds
TimeSpan.FromSeconds(60 - DateTime.Now.Second),
// then run every minute
() => Scheduler.Default.SchedulePeriodic(TimeSpan.FromMinutes(1), work));
Console.WriteLine("Press return.");
Console.ReadLine();
Read here (search for "Introducing ISchedulerPeriodic") to see all the issues this is taking care of: http://blogs.msdn.com/b/rxteam/archive/2012/06/20/reactive-extensions-v2-0-release-candidate-available-now.aspx
I jsut wrote this class using the WPF DispatcherTimer but you can swap the dispatcher for any timer that supports changing when it's woken from sleep state.
The class is constructed with a fixed time step and supprts Start/Stop/Reset, Start/Stop/Start works like a resume operation. The timer is like a stopwatch in that regard.
A clock implementation would simply create the class with a interval of 1 second and listen to the event. Be wary though that this is a real-time clock, if the tick event takes longer than the interval to finish you'll notice that the clock will try and catch up to real-time this will cause a burst of tick events being raised.
public class FixedStepDispatcherTimer
{
/// <summary>
/// Occurs when the timer interval has elapsed.
/// </summary>
public event EventHandler Tick;
DispatcherTimer timer;
public bool IsRunning { get { return timer.IsEnabled; } }
long step, nextTick, n;
public TimeSpan Elapsed { get { return new TimeSpan(n * step); } }
public FixedStepDispatcherTimer(TimeSpan interval)
{
if (interval < TimeSpan.Zero)
{
throw new ArgumentOutOfRangeException("interval");
}
this.timer = new DispatcherTimer();
this.timer.Tick += new EventHandler(OnTimerTick);
this.step = interval.Ticks;
}
TimeSpan GetTimerInterval()
{
var interval = nextTick - DateTime.Now.Ticks;
if (interval > 0)
{
return new TimeSpan(interval);
}
return TimeSpan.Zero; // yield
}
void OnTimerTick(object sender, EventArgs e)
{
if (DateTime.Now.Ticks >= nextTick)
{
n++;
if (Tick != null)
{
Tick(this, EventArgs.Empty);
}
nextTick += step;
}
var interval = GetTimerInterval();
Trace.WriteLine(interval);
timer.Interval = interval;
}
public void Reset()
{
n = 0;
nextTick = 0;
}
public void Start()
{
var now = DateTime.Now.Ticks;
nextTick = now + (step - (nextTick % step));
timer.Interval = GetTimerInterval();
timer.Start();
}
public void Stop()
{
timer.Stop();
nextTick = DateTime.Now.Ticks % step;
}
}
Create a method or put this code where you want the timer to start:
int time = 60 - DateTime.Now.Second; // Gets seconds to next minute
refreshTimer.Interval = time * 1000;
refreshTimer.Start();
And then on your tick event set the interval to 60000:
private void refreshTimer_Tick(object sender, EventArgs e)
{
refreshTimer.Interval = 60000; // Sets interval to 60 seconds
// Insert Refresh logic
}
By making use of ReactiveExtensions you could use the following code if you were interested in doing something as simple as printing to the console.
using System;
using System.Reactive.Linq;
namespace ConsoleApplicationExample
{
class Program
{
static void Main()
{
Observable.Interval(TimeSpan.FromMinutes(1))
.Subscribe(_ =>
{
Console.WriteLine(DateTime.Now.ToString());
});
Console.WriteLine(DateTime.Now.ToString());
Console.ReadLine();
}
}
}
Running a bit of code to see if the minute has changed once per second should not require much CPU time, and should be acceptable.
What about Quartz.NET? I think its a good framework to do timed actions.
You could set up two timers. An initial short interval timer (perhaps to fire every second, but dependent on how presice the second timer must fire on the minute).
You would fire the short interval timer only until the desired start time of the main interval timer is reached. Once the initial time is reached, the second main interval timer can be activated, and the short interval timer can be deactivated.
void StartTimer()
{
shortIntervalTimer.Interval = 1000;
mainIntervalTimer.Interval = 60000;
shortIntervalTimer.Tick +=
new System.EventHandler(this.shortIntervalTimer_Tick);
mainIntervalTimer.Tick +=
new System.EventHandler(mainIntervalTimer_Tick);
shortIntervalTimer.Start();
}
private void shortIntervalTimer_Tick(object sender, System.EventArgs e)
{
if (DateTime.Now.Second == 0)
{
mainIntervalTimer.Start();
shortIntervalTimer.Stop();
}
}
private void mainIntervalTimer_Tick(object sender, System.EventArgs e)
{
// do what you need here //
}
Alternatively, you could sleep to pause execution until it times out which should be close to your desired time. This will only wake the computer when the sleep finishes so it'll save you CPU time and let the CPU power down between processing events.
This has the advantage of modifying the timeout so that it will not drift.
int timeout = 0;
while (true) {
timeout = (60 - DateTime.Now.Seconds) * 1000 - DateTime.Now.Millisecond;
Thread.Sleep(timeout);
// do your stuff here
}
Use a timer set to run every second (or millisecond, whatever your accuracy threshold is), and then code the method to run your functionality if and only if the current time is within that threshold past the "on the minute" point.
What I'm using for scheduled tasks is a System.Threading.Timer(System.Threading.TimerCallback, object, int, int) with the callback set to the code I want to execute based on the interval which is supplied in milliseconds for the period value.
What about a combination of aquinas' answer and 'polling': (apologies for the mixture of languages)
def waitForNearlyAMinute:
secsNow = DateTime.Now.Second;
waitFor = 55 - secsNow;
setupTimer(waitFor, pollForMinuteEdge)
def pollForMinuteEdge:
if (DateTime.Now.Second == 0):
print "Hello, World!";
waitForNearlyAMinute();
else:
setupTimer(0.5, pollForMinuteEdge)
I have a solution based on Environment.TickCount
static void Main(string[] args)
{
//constatnt total miliseconds to one minute
const Int32 minuteMilisecond = 60 * 1000;
//get actual datetime
DateTime actualDateTime = DateTime.UtcNow;
//compenzation to one minute
Int32 nexTimer = Environment.TickCount + ((59 - actualDateTime.Second) * 1000) + (999 - actualDateTime.Millisecond);
//random fuction to simulate different delays on thread
Random rnd = new Random();
//main loop
while (true)
{
if (Environment.TickCount > nexTimer)
{
nexTimer += minuteMilisecond;
//execute your code here every minute
Console.WriteLine($"actual DateTime: {DateTime.Now.ToString("yyyy.MM.dd HH:mm:ss:ffff")}");
}
//random sleep between 100 - 200 ms
Thread.Sleep(rnd.Next(100, 200));
}
}