Improve signal handling in RPC example (#5974) (#5991)

* Refs #23569: Improve signal handling



* Refs #23569: Fix signal handling



* Refs #23569: Review - Apply suggestions



---------


(cherry picked from commit 0a9b827)

Signed-off-by: Carlosespicur <[email protected]>
Co-authored-by: Carlos Espinoza Curto <[email protected]>

Author: mergify[bot]

examples/cpp/rpc/Application.hpp

@@ -43,6 +43,9 @@ class Application
     //! Trigger the end of execution
     virtual void stop() = 0;
 
+    //! Check if the application is stopped
+    virtual bool is_stopped() const = 0;
+
     //! Factory method to create applications based on configuration
     static std::shared_ptr<Application> make_app(
             const CLIParser::config& config,

examples/cpp/rpc/ClientApp.hpp

@@ -221,6 +221,11 @@ class ClientApp : public Application
 
     void stop() override;
 
+    bool is_stopped() const override
+    {
+        return stop_.load();
+    }
+
 protected:
 
     //! Create a participant for internal RPCDDS entities
@@ -238,11 +243,6 @@ class ClientApp : public Application
     bool ping_server(
             std::size_t attempts);
 
-    bool is_stopped()
-    {
-        return stop_.load();
-    }
-
     std::shared_ptr<calculator_example::Calculator> client_;
     dds::DomainParticipant* participant_;
     CLIParser::config config_;

examples/cpp/rpc/ServerApp.hpp

@@ -45,18 +45,18 @@ class ServerApp : public Application
 
     void stop() override;
 
+    bool is_stopped() const override
+    {
+        return stop_.load();
+    }
+
 protected:
 
     void create_participant();
 
     void create_server(
             const std::string& server_name);
 
-    bool is_stopped()
-    {
-        return stop_.load();
-    }
-
 private:
 
     class ServerImpl : public calculator_example::CalculatorServerImplementation,

examples/cpp/rpc/main.cpp

@@ -17,13 +17,16 @@
  *
  */
 
+#include <condition_variable>
 #include <csignal>
 #include <functional>
 #include <iostream>
 #include <memory>
+#include <mutex>
 #include <stdexcept>
 #include <string>
 #include <thread>
+#include <atomic>
 
 #include "app_utils.hpp"
 #include "Application.hpp"
@@ -34,6 +37,8 @@ using eprosima::fastdds::dds::Log;
 using namespace eprosima::fastdds::examples::rpc;
 
 std::function<void(int)> stop_app_handler;
+std::atomic<bool> stop_requested {false};
+std::atomic<int> received_signum {0};
 
 void signal_handler(
         int signum)
@@ -67,10 +72,8 @@ int main(
 
         stop_app_handler = [&](int signum)
                 {
-                    client_server_info("main",
-                            CLIParser::parse_signal(signum) << " received, stopping " << app_name << " execution.");
-
-                    app->stop();
+                    received_signum.store(signum);
+                    stop_requested.store(true);
                 };
 
         signal(SIGINT, signal_handler);
@@ -83,6 +86,23 @@ int main(
         client_server_info("main",
                 app_name << " running. Please press Ctrl+C to stop the " << app_name << " at any time.");
 
+        while (!app->is_stopped())
+        {
+            if (stop_requested.load())
+            {
+                client_server_info("main",
+                        CLIParser::parse_signal(
+                            received_signum.load()) << " received, stopping " << app_name << " execution.");
+
+                app->stop();
+                break;
+            }
+            else
+            {
+                std::this_thread::sleep_for(std::chrono::milliseconds(10));
+            }
+        }
+
         thread.join();
     }