Generating Unique Numeric IDs using DateTime.Now.Ticks

Question

I need to generate a unique numeric ID to attach to an incoming request. This ID is used only temporarily to track the request and will be discarded once the request has completed processing. This ID will only be used in the context of this application but will need to be assigned in a high performance multi-threaded way.

I was thinking of using DateTime.Now.Ticks for this ID but would like to know if DateTime.Now.Ticks could still generate a colliding ID if simultaneous requests are being concurrently being processed?

If anyone could suggest a better way to generate these IDs (preferably one that is not Int64 like Tick is) in a multi-threaded environment, please let me know. Something as simple as an incrementing number would suffice even, if only I didn't have to lock the number before incrementing.

Thanks a lot for any help.

Answer 1

You just need to use a static variable that is incremented each time you want another unique value. You can make this thread safe and still very fast by using the Interlocked.Increment method...

// Declaration
private static int safeInstanceCount = 0;

// Usage
{
      ...
      Interlocked.Increment(ref safeInstanceCount);
      ...
}