Thread safe DateTime update using Interlocked.*
c#, datetime, interlocked, lock-free, multithreading
Solution
Yes, you can do this. Your biggest problem may be that DateTime.Ticks only has a resolution of ~20 ms. So it doesn't really matter if you keep a `DateTime last` or a `long ticks` variable. But since there is no overload of Exchange for DateTime, you need to use `long`.
Problem
Can I use an `Interlocked.*` synchronization method to update a `DateTime` variable? I wish to maintain a last-touch time stamp in memory. Multiple http threads will update the last touch `DateTime` variable. I appreciate that `DateTime` variables are value types that are replaced rather than updated. The best I can come up with is to hold the timestamp as total ticks in a long ``` class x { long _lastHit; void Touch() { Interlocked.Exchange(ref _lastHit, DateTime.Now.Ticks); } } ```