Function runChildWorker

server/worker.go:194–423

runChildWorker handles a single client connection in a child process. Returns the appropriate exit code.

(tcpConn *net.TCPConn, cfg *ChildConfig)

// runChildWorker handles a single client connection in a child process.
// Returns the appropriate exit code.
func runChildWorker(tcpConn *net.TCPConn, cfg *ChildConfig) int {
	// Set up signal handling for graceful shutdown and query cancellation
	sigChan := make(chan os.Signal, 1)
	signal.Notify(sigChan, syscall.SIGTERM, syscall.SIGINT, syscall.SIGUSR1)

	// Create a context for shutdown signals (SIGTERM/SIGINT)
	shutdownCtx, shutdownCancel := context.WithCancel(context.Background())
	defer shutdownCancel()

	// Create a channel to signal query cancellation (SIGUSR1).
	// This is separate from shutdown so we can cancel queries without closing
	// the connection. Each SIGUSR1 delivers ONE cancel token (coalescing
	// bursts) that the in-flight query's context goroutine consumes — the
	// channel must never be closed: a closed channel is permanently readable,
	// so a single cancel would instantly cancel every subsequent query on the
	// connection (the session could never run another statement).
	queryCancelCh := make(chan struct{}, 1)

	// Handle signals in a goroutine
	go func() {
		for sig := range sigChan {
			switch sig {
			case syscall.SIGTERM, syscall.SIGINT:
				slog.Info("Received shutdown signal", "signal", sig)
				shutdownCancel()
			case syscall.SIGUSR1:
				slog.Info("Received query cancel signal")
				notifyQueryCancel(queryCancelCh)
			}
		}
	}()

	// Load TLS certificate
	cert, err := tls.LoadX509KeyPair(cfg.TLSCertFile, cfg.TLSKeyFile)
	if err != nil {
		slog.Error("Failed to load TLS certificates", "error", err)
		return ExitError
	}

	tlsConfig := &tls.Config{
		Certificates: []tls.Certificate{cert},
	}

	// Complete TLS handshake with timeout to prevent slow clients from holding resources
	// Parent has already sent 'S' response to SSL request, we just need to do the handshake
	tlsConn := tls.Server(tcpConn, tlsConfig)

	// Set deadline for TLS handshake (30 seconds should be plenty)
	if err := tlsConn.SetDeadline(time.Now().Add(30 * time.Second)); err != nil {
		slog.Error("Failed to set TLS handshake deadline", "error", err)
		return ExitError
	}

	if err := tlsConn.Handshake(); err != nil {
		slog.Error("TLS handshake failed", "error", err, "remote_addr", cfg.RemoteAddr)
		return ExitError
	}