feat: add heartbeat feature to auto-terminate program on failure by wen2so · Pull Request #425 · nam20485/OdbDesign

wen2so · 2025-07-17T03:08:56Z

Detect heartbeat status every 5 seconds. If no heartbeat is received within 5 seconds, the program will exit automatically.

Implements: #424

gemini-code-assist

Summary of Changes

Hello @wen2so, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a critical reliability feature to the OdbDesignServer by implementing a heartbeat mechanism. It ensures the server's responsiveness by adding a new API endpoint that updates an internal timestamp, coupled with a background monitor that automatically terminates the application if it becomes unresponsive. This proactive self-termination helps maintain system stability and resource integrity.

Highlights

Heartbeat Endpoint: I've added a new /healthz/heartbeat endpoint to the HealthCheckController. Calling this endpoint updates an internal timestamp, signaling that the server is active and responsive.
Heartbeat Monitoring: A new background thread has been introduced in OdbDesignServerApp that continuously monitors the lastHeartbeat_ timestamp. This thread checks every second if the timestamp has been updated recently.
Application Self-Termination: If the lastHeartbeat_ timestamp is not updated for more than 5 seconds, the monitorHeartbeat thread will automatically terminate the application by calling exit(0). This ensures that unresponsive server instances are automatically shut down.
Health Check Response Simplification: The response messages for existing /healthz/live, /healthz/ready, and /healthz/started endpoints have been simplified, removing the 'healthy: ' prefix for cleaner output.
API Documentation Update: The swagger/odbdesign-server-0.9-swagger.yaml file has been updated to include the definition for the new /healthz/heartbeat GET endpoint.

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Detect heartbeat status every 5 seconds. If no heartbeat is received within 5 seconds, the program will exit automatically.

gemini-code-assist

Code Review

This pull request introduces a heartbeat mechanism to monitor the server's health and terminate it if it becomes unresponsive. The implementation involves a new heartbeat endpoint and a background thread to check the heartbeat status. The review focuses on improving the design by ensuring a graceful shutdown instead of an abrupt exit, and improving code clarity by replacing magic numbers with named constants. These changes will make the code more robust and maintainable.

gemini-code-assist · 2025-07-17T03:12:05Z

OdbDesignServer/OdbDesignServerApp.cpp

+			if (diff > std::chrono::seconds(5))
+			{
+				std::cerr << "Heartbeat timeout, exiting..." << std::endl;
+				exit(0);


Calling exit(0) will cause an immediate, forceful termination of the process. This prevents proper cleanup. A more graceful shutdown can be achieved by stopping the Crow application¹. This allows the run() method to return and the application to perform any necessary cleanup before exiting.

Style Guide References

Suggested change

exit(0);

OdbDesignServerApp::inst_->crow_app().stop();

return;

Footnotes

Use crow_app().stop() for a graceful shutdown. (link) ↩

gemini-code-assist · 2025-07-17T03:12:06Z

OdbDesignServer/OdbDesignServerApp.h

+		static OdbDesignServerApp* inst_;
+		// store last heartbeat time
+		std::atomic<std::chrono::steady_clock::time_point> lastHeartbeat_;


These members (inst_ and lastHeartbeat_) are public, which breaks encapsulation. The inst_ static pointer, in particular, implements a singleton pattern via a public member, which introduces global state and makes code difficult to test and reason about¹. These should be made private.

Style Guide References

Footnotes

Avoid public members for internal state. (link) ↩

gemini-code-assist · 2025-07-17T03:12:06Z

OdbDesignServer/Controllers/HealthCheckController.cpp

+	crow::response HealthCheckController::health_check_heartbeat(const crow::request& req)
+	{
+        // update last heartbeat
+        OdbDesignServerApp::inst_->updateLastHeartbeat();


This line uses the global singleton inst_ to access the application object. This creates a tight coupling and dependency on a global variable¹. The RouteController base class already provides access to the server application via the m_serverApp member. You can use dynamic_cast to safely cast it to your specific application class and call the method. This approach uses dependency injection and avoids global state, which is a much cleaner design.

Style Guide References

Suggested change

OdbDesignServerApp::inst_->updateLastHeartbeat();

dynamic_cast<OdbDesignServerApp&>(m_serverApp).updateLastHeartbeat();

Footnotes

Avoid global singletons. (link) ↩

As Gemini states, you already have access to m_serverApp. You can use that and get rid of the singleton object.

gemini-code-assist · 2025-07-17T03:12:06Z

OdbDesignServer/OdbDesignServerApp.cpp

+		auto lastTime = OdbDesignServerApp::inst_->lastHeartbeat_.load(std::memory_order_relaxed);
+		while (true)
+		{
+			std::this_thread::sleep_for(std::chrono::seconds(1));
+			auto now = std::chrono::steady_clock::now();
+			auto diff = now - lastTime;
+			// check heartbeat
+			if (diff > std::chrono::seconds(5))
+			{
+				std::cerr << "Heartbeat timeout, exiting..." << std::endl;
+				exit(0);
+			}
+			lastTime = OdbDesignServerApp::inst_->lastHeartbeat_.load(std::memory_order_relaxed);
+		}


This function uses magic numbers for time intervals (1 for the sleep duration on line 59 and 5 for the timeout on line 63). It's a best practice to define these as named constants to improve readability and maintainability¹.

Style Guide References

Footnotes

Define time intervals as named constants. (link) ↩

wen2so · 2025-07-17T03:13:55Z

consider add an args param to enable or disable this feature

- Add heartbeatInterval() method to OdbDesignArgs class - Implement heartbeat interval configuration in OdbDesignServerApp - Update usage string to include new heartbeat interval option

sonarqubecloud · 2025-07-17T06:00:01Z

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

sonarqubecloud · 2025-09-02T08:02:39Z

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

nam20485

I don't understand why you need this heartbeat.

Usually it is the orchestration SW's (e.g. Docker or Kubernetes) responsibility to check the health check endpoints (which already exist) and kill the process if they don't respond.

What is your use case for checking and terminating from inside of the process?

nam20485 · 2025-09-08T09:35:03Z

OdbDesignServer/Controllers/HealthCheckController.cpp

+	crow::response HealthCheckController::health_check_heartbeat(const crow::request& req)
+	{
+        // update last heartbeat
+        OdbDesignServerApp::inst_->updateLastHeartbeat();


As Gemini states, you already have access to m_serverApp. You can use that and get rid of the singleton object.

wen2so · 2025-09-09T07:26:23Z

Considering that this C++ program is intended to be used as a library and invoked by programs written in other languages, and given that in a standalone deployment (without container management tools like Docker), the C++ program must terminate synchronously if the calling program crashes or exits unexpectedly — to avoid running as an orphaned process — a heartbeat mechanism is therefore required.

wen2so requested a review from nam20485 as a code owner July 17, 2025 03:08

gemini-code-assist bot reviewed Jul 17, 2025

View reviewed changes

feat: add heartbeat feature

b10846b

Detect heartbeat status every 5 seconds. If no heartbeat is received within 5 seconds, the program will exit automatically.

wen2so force-pushed the dev/heartbeat branch from 5147939 to b10846b Compare July 17, 2025 03:11

gemini-code-assist bot reviewed Jul 17, 2025

View reviewed changes

feat: add heartbeat interval configuration option

75ed67f

- Add heartbeatInterval() method to OdbDesignArgs class - Implement heartbeat interval configuration in OdbDesignServerApp - Update usage string to include new heartbeat interval option

Merge branch 'development' into dev/heartbeat

4d0649c

nam20485 reviewed Sep 8, 2025

View reviewed changes

	exit(0);
	OdbDesignServerApp::inst_->crow_app().stop();
	return;

	OdbDesignServerApp::inst_->updateLastHeartbeat();
	dynamic_cast<OdbDesignServerApp&>(m_serverApp).updateLastHeartbeat();

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wen2so commented Jul 17, 2025

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sonarqubecloud bot commented Jul 17, 2025

Quality Gate passed

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wen2so commented Sep 9, 2025

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wen2so commented Jul 17, 2025 •

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