refactor: rework limiter, traffic accounting, and logging (nlog)

internal/limiter/speedtracker_test.go

@@ -2,6 +2,7 @@ package limiter
 
 import (
 	"testing"
+	"time"
 
 	"github.com/cedar2025/xboard-node/internal/panel"
 )
@@ -121,3 +122,26 @@ func TestSpeedTracker_UpdateBuckets_RemovesUsers(t *testing.T) {
 		t.Error("expected no bucket for removed user 2")
 	}
 }
+
+// Regression: log callback must not run while UpdateBuckets holds t.mu.Lock,
+// otherwise callbacks that call LimitedUserCount() self-deadlock on RWMutex.
+func TestSpeedTracker_UpdateBuckets_LogCallbackMayCallLimitedUserCount(t *testing.T) {
+	l := New()
+	st := NewSpeedTracker(l)
+	l.UpdateUsers([]panel.User{{ID: 1, UUID: "u1", SpeedLimit: 1}})
+	st.SetLogCallback(func(msg string) {
+		_ = st.LimitedUserCount()
+	})
+
+	done := make(chan struct{})
+	go func() {
+		st.UpdateBuckets()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(2 * time.Second):
+		t.Fatal("deadlock: UpdateBuckets did not finish (log callback vs RWMutex)")
+	}
+}