Marcin Celej

Generating Unique Id (Int64) in your application

I needed to generate some unique number in my application. I could use GUID, but it was too large for me (I need to keep lots of unique identifiers). I found something like this:

[System.Runtime.InteropServices.DllImport("Kernel32.dll")]
private static extern int QueryPerformanceFrequency(ref System.Int64 frequency);

[System.Runtime.InteropServices.DllImport("Kernel32.dll")]
private static extern int QueryPerformanceCounter(ref System.Int64 performanceCount);

public static long GenerateUniqueId()
{
      System.Int64 id = 0;
      QueryPerformanceFrequency(ref id);
      QueryPerformanceCounter(ref id);
      return id;
}

This code generates Int64 (long) unique number (at least I hope it is unique). The uniqueness is in the scope of process. So two processes can generate the same number, but it should be always unique in a single process (I am not sure about two threads invoking the same GenerateUniqueId() method.

Print | posted on Friday, September 29, 2006 5:43 PM |