[feat] implementation for send side congestion controller

src/qos/constrained.h

@@ -0,0 +1,31 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2025-01-14
+ * Copyright (c) 2025 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _CONSTRAIN_H_
+#define _CONSTRAIN_H_
+
+#include <optional>
+#include <string>
+
+template <typename T>
+class Constrained {
+ public:
+  Constrained(T default_value, std::optional<T> lower_limit,
+              std::optional<T> upper_limit)
+      : value_(default_value),
+        lower_limit_(lower_limit),
+        upper_limit_(upper_limit) {}
+  T Get() const { return value_; }
+  operator T() const { return Get(); }
+  const T* operator->() const { return &value_; }
+
+ private:
+  T value_;
+  std::optional<T> lower_limit_;
+  std::optional<T> upper_limit_;
+};
+
+#endif