fix(nicehash): count stale job hits

Co-Authored-By: Virgil <virgil@lethean.io>

splitter/nicehash/storage.go

@@ -21,6 +21,7 @@ type NonceStorage struct {
 	job     proxy.Job              // current job from pool
 	prevJob proxy.Job              // previous job (for stale submit validation)
 	cursor  int                    // search starts here (round-robin allocation)
+	expired uint64                 // stale job ID hits for the previous job
 	mu      sync.Mutex
 }
 
@@ -132,6 +133,7 @@ func (s *NonceStorage) JobForID(id string) (job proxy.Job, valid bool, expired b
 		return s.job, true, false
 	}
 	if s.prevJob.IsValid() && s.prevJob.ClientID != "" && id == s.prevJob.JobID {
+		s.expired++
 		return s.prevJob, true, true
 	}
 	return proxy.Job{}, false, false
@@ -166,6 +168,16 @@ func (s *NonceStorage) SlotCount() (free int, dead int, active int) {
 	return free, dead, active
 }
 
+// ExpiredCount returns the number of times the previous job ID has been accepted as stale.
+//
+//	count := storage.ExpiredCount()
+func (s *NonceStorage) ExpiredCount() uint64 {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	return s.expired
+}
+
 // Miners returns a snapshot of the active miner map.
 func (s *NonceStorage) Miners() map[int64]*proxy.Miner {
 	s.mu.Lock()

splitter/nicehash/storage_test.go

@@ -60,6 +60,9 @@ func TestNonceStorage_IsValidJobID_Ugly(t *testing.T) {
 	if !storage.IsValidJobID("job-1") {
 		t.Fatal("expected previous job ID from same client to remain valid")
 	}
+	if got := storage.ExpiredCount(); got != 1 {
+		t.Fatalf("expected stale job lookups to increment the expired counter, got %d", got)
+	}
 }
 
 func TestNonceStorage_IsValidJobID_BadClientID(t *testing.T) {