fix: clock sequence race and add stress test;

[atlet99]

Issue - #216

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (e1fb84e) to head (73dc725).

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #219   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          517       532   +15     
=========================================
+ Hits           517       532   +15     

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[Copilot]

Pull Request Overview

This PR fixes a race condition in Version-1 UUID generation's clock sequence handling and adds comprehensive stress testing to verify the fix. The issue occurred when the 14-bit clock sequence counter overflowed without proper handling, potentially causing UUID collisions.

• Implements proper 14-bit clock sequence wrapping with bitmask operation
• Adds mandatory timestamp advancement when sequence wraps to zero
• Introduces stress test with table-driven concurrent scenarios

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
generator.go	Fixed clock sequence race condition by adding proper 14-bit wrapping and timestamp advancement
race_v1_test.go	Added comprehensive concurrent stress test to verify UUID uniqueness under high contention

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[Copilot]

Using runtime.Gosched() in a tight loop creates a busy-wait pattern that can consume CPU resources. Consider using a small sleep duration like time.Sleep(time.Microsecond) to reduce CPU usage while waiting for timestamp advancement.

Suggested change

	// Yield the processor briefly to avoid busy-waiting.
	runtime.Gosched()
	// Sleep briefly to avoid busy-waiting and reduce CPU usage.
	time.Sleep(time.Microsecond)

[cameracker]

@atlet99 This is backed up by another stackoverflow thread here: https://stackoverflow.com/a/57703034/31566036

What do you think of doing a sleep instead? Might need to be a millisecond sleep instead of a microsecond though...

[Copilot]

The dupCount variable is accessed without atomic operations while other variables use atomic.AddUint32(). This creates inconsistent synchronization patterns. Consider using atomic.AddUint32(&dupCount, 1) for consistency.

[cameracker]

I'm not that worried about the consistency with how the ints are incremented in this case.