added kernel alive variable

test/test_debugger.cpp

@@ -976,6 +976,10 @@ void debugger_client::start()
 void debugger_client::shutdown()
 {
     m_client.stop_channels();
+    if (!m_client.kernel_alive)
+    {
+        throw std::runtime_error("Kernel is not alive. Cannot send shutdown request.");
+    }
     m_client.send_on_control("shutdown_request", make_shutdown_request());
     m_client.receive_on_control();
 }

test/xeus_client.cpp

@@ -34,14 +34,26 @@ xeus_logger_client::xeus_logger_client(xeus::xcontext& context,
     std::ofstream out(m_file_name);
     out << "STARTING CLIENT" << std::endl;
 
-    // TODO
     p_client->connect();
+    register_kernel_status_listener();
 }
 
 xeus_logger_client::~xeus_logger_client()
 {
 }
 
+void xeus_logger_client::register_kernel_status_listener()
+{
+    p_client->register_kernel_status_listener([this](bool status) {
+        handle_kernel_status_message(status);
+    });
+}
+
+void xeus_logger_client::handle_kernel_status_message(bool status)
+{
+    kernel_alive = status;
+}
+
 void xeus_logger_client::send_on_shell(const std::string& msg_type, nl::json content)
 {
     nl::json header = xeus::make_header(msg_type, m_user_name, xeus::new_xguid());

test/xeus_client.hpp

@@ -50,8 +50,13 @@ class xeus_logger_client
     void stop_channels();
     void log_message(nl::json msg);
 
+    void register_kernel_status_listener();
+    bool kernel_alive = false;
+
 private:
 
+    void handle_kernel_status_message(bool status);
+
     std::string m_user_name;
     std::string m_file_name;
     std::mutex m_file_mutex;