[英]How do I change the interval time in System.Threading.Timer from the callback function of this timer?
How do I change the interval in System.Threading.Timer from the callback function of this timer?如何从此计时器的回调 function 更改 System.Threading.Timer 中的间隔? Is this correct?这个对吗?
Doing so.这样做。 Did not happen.没有发生。
public class TestTimer
{
private static Timer _timer = new Timer(TimerCallBack);
public void Run()
{
_timer.Change(TimeSpan.Zero, TimeSpan.FromMinutes(1));
}
private static void TimerCallBack(object obj)
{
if(true)
_timer.Change(TimeSpan.Zero, TimeSpan.FromMinutes(10));
}
}
This line generate infinite recursion:此行生成无限递归:
if(true)
_timer.Change(TimeSpan.Zero, TimeSpan.FromMinutes(10));
The first parameter forces TimerCallBack
to execute right away.第一个参数强制TimerCallBack
立即执行。 So it executes it again and again indefinitely.所以它会无限期地一次又一次地执行它。
The fix would be修复将是
if(true)
_timer.Change(TimeSpan.FromMinutes(10), TimeSpan.FromMinutes(10));
The problem is that your call to Change
specifies that the next call should happen immediately .问题是您对Change
的调用指定下一次调用应该立即发生。 If you're going to call Change
every time, you can just use a period of Timeout.Infinite
(which is just a constant of -1) to tell it to avoid repeating at all after the next time - but it will still keep firing, because that next time, you reset it.如果你要每次都调用Change
,你可以使用Timeout.Infinite
的一段时间(它只是一个常数 -1)来告诉它在下一次之后完全避免重复 - 但它仍然会继续触发,因为下次你重置它。 For example:例如:
using System;
using System.Threading;
static class Program
{
private static Timer timer = new Timer(TimerCallBack);
public static void Main()
{
timer.Change(TimeSpan.Zero, TimeSpan.FromSeconds(1));
Thread.Sleep(10000);
}
private static void TimerCallBack(object obj)
{
Console.WriteLine("{0}: Fired", DateTime.Now);
timer.Change(TimeSpan.FromSeconds(3),
TimeSpan.FromMilliseconds(Timeout.Infinite));
}
}
Alternatively, you could change it just once, and then leave it:或者,您可以只更改一次,然后离开它:
using System;
using System.Threading;
static class Program
{
private static Timer timer = new Timer(TimerCallBack);
private static bool changed = false;
public static void Main()
{
timer.Change(TimeSpan.Zero, TimeSpan.FromSeconds(1));
Thread.Sleep(10000);
}
private static void TimerCallBack(object obj)
{
Console.WriteLine("{0}: Fired", DateTime.Now);
if (!changed)
{
changed = true;
TimeSpan interval = TimeSpan.FromSeconds(3);
timer.Change(interval, interval);
}
}
}
Note that nothing is using the initial interval (1 second in the samples above) in either case, because we're calling Change
immediately - if you really want a different time before the first call, don't use TimeSpan.Zero
in the initial call to Change
.请注意,在任何一种情况下都没有使用初始间隔(上面的示例中为 1 秒),因为我们正在立即调用Change
- 如果您真的想要在第一次调用之前有一个不同的时间,请不要在初始时使用TimeSpan.Zero
调用Change
。
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