server state test

include/td/misc/Signal.h

@@ -11,7 +11,8 @@ namespace utils {
 template <typename... Args>
 class Signal : private NonCopyable {
   private:
-	using CallBack = std::function<void(Args...)>;
+	using FnType = void(Args...);
+	using CallBack = std::function<FnType>;
 
 	std::vector<CallBack> m_Callbacks;
 
@@ -20,6 +21,12 @@ class Signal : private NonCopyable {
 		m_Callbacks.push_back(std::move(a_Callback));
 	}
 
+	void Disconnect(const CallBack& a_Callback) {
+		auto it = std::find_if(m_Callbacks.begin(), m_Callbacks.end(),
+			[&a_Callback](CallBack& callback) { return a_Callback.template target<FnType>() == callback.template target<FnType>(); });
+		m_Callbacks.erase(it);
+	}
+
 	void operator()(Args... args) const {
 		for (const CallBack& callback : m_Callbacks) {
 			callback(args...);