fix default selector

internal/util/selector/key.go

@@ -0,0 +1,27 @@
+package selector
+
+import (
+	"context"
+)
+
+type hashKey struct{}
+
+type Hash struct {
+	Source string
+	Value  int
+}
+
+var (
+	clientHashKey = &hashKey{}
+)
+
+func ContextWithHash(ctx context.Context, hash *Hash) context.Context {
+	return context.WithValue(ctx, clientHashKey, hash)
+}
+
+func HashFromContext(ctx context.Context) *Hash {
+	if v, _ := ctx.Value(clientHashKey).(*Hash); v != nil {
+		return v
+	}
+	return nil
+}