C＃System.Threading.Timer及其状态对象

Question

I am writing a C# program that uses System.Threading.Timer to timeout on a UDP socket ReceiveAsync call.

My program polls a remote device, sending a UDP packet and expecting one in return.

I use the timer in one shot mode calling Timer.Change every time I want a new timeout period.

For every occurance of a timeout I'd like the timeout handler to have a different piece of information.

If I change the object I pass to the Timer on creation it doesn't seem to change when the handler executes.

Is the only way to do this to destroy the timer and create a new one?

Thanks,

Answer 1

Are you passing a struct instead of a class object? Structs are value types, you'll get a copy back of the first version of it. Changes you make will be lost since the state doesn't get passed by ref in the callback. Using a class instead of a struct is the simple solution.

Storing the state object in your own class is another approach.

Answer 2

您传递的对象可以是一个数组，其中包含您在每次超时时替换的单个元素。

Answer 3

Consider this cheap wrapper:

sealed class TimerWrapper : IDisposable
{
    readonly Timer timer;

    object State { get; set; }

    public TimerWrapper(TimerCallback callback) 
    {
        timer = new Timer(delegate { callback(State); });
    }

    public void Change(object state, TimeSpan dueTime, TimeSpan period)
    {
        timer.Change(dueTime, period);
        State = state;
    }

    public void Dispose()
    {
        timer.Dispose();
    }
}

Please note that using the code above can lead to unexpected behaviour in some rare race conditions.

Answer 4

使用WaitHandle并锁定以进行同步