refactor: redistribute main.rs into new modules for app & service initialization

src/signals.rs

@@ -0,0 +1,106 @@
+use crate::services::ServiceResult;
+use crate::services::manager::ServiceManager;
+use std::process::ExitCode;
+use std::time::Duration;
+use tokio::signal;
+use tracing::{error, info, warn};
+
+/// Handle application shutdown signals and graceful shutdown
+pub async fn handle_shutdown_signals(
+    mut service_manager: ServiceManager,
+    shutdown_timeout: Duration,
+) -> ExitCode {
+    // Set up signal handling for both SIGINT (Ctrl+C) and SIGTERM
+    let ctrl_c = async {
+        signal::ctrl_c()
+            .await
+            .expect("Failed to install CTRL+C signal handler");
+        info!("received ctrl+c, gracefully shutting down...");
+    };
+
+    #[cfg(unix)]
+    let sigterm = async {
+        use tokio::signal::unix::{SignalKind, signal};
+        let mut sigterm_stream =
+            signal(SignalKind::terminate()).expect("Failed to install SIGTERM signal handler");
+        sigterm_stream.recv().await;
+        info!("received SIGTERM, gracefully shutting down...");
+    };
+
+    #[cfg(not(unix))]
+    let sigterm = async {
+        // On non-Unix systems, create a future that never completes
+        // This ensures the select! macro works correctly
+        std::future::pending::<()>().await;
+    };
+
+    // Main application loop - wait for services or signals
+    let mut exit_code = ExitCode::SUCCESS;
+
+    tokio::select! {
+        (service_name, result) = service_manager.run() => {
+            // A service completed unexpectedly
+            match result {
+                ServiceResult::GracefulShutdown => {
+                    info!(service = service_name, "service completed gracefully");
+                }
+                ServiceResult::NormalCompletion => {
+                    warn!(service = service_name, "service completed unexpectedly");
+                    exit_code = ExitCode::FAILURE;
+                }
+                ServiceResult::Error(e) => {
+                    error!(service = service_name, error = ?e, "service failed");
+                    exit_code = ExitCode::FAILURE;
+                }
+            }
+
+            // Shutdown remaining services
+            exit_code = handle_graceful_shutdown(service_manager, shutdown_timeout, exit_code).await;
+        }
+        _ = ctrl_c => {
+            // User requested shutdown via Ctrl+C
+            info!("user requested shutdown via ctrl+c");
+            exit_code = handle_graceful_shutdown(service_manager, shutdown_timeout, ExitCode::SUCCESS).await;
+        }
+        _ = sigterm => {
+            // System requested shutdown via SIGTERM
+            info!("system requested shutdown via SIGTERM");
+            exit_code = handle_graceful_shutdown(service_manager, shutdown_timeout, ExitCode::SUCCESS).await;
+        }
+    }
+
+    info!(exit_code = ?exit_code, "application shutdown complete");
+    exit_code
+}
+
+/// Handle graceful shutdown of remaining services
+async fn handle_graceful_shutdown(
+    mut service_manager: ServiceManager,
+    shutdown_timeout: Duration,
+    current_exit_code: ExitCode,
+) -> ExitCode {
+    match service_manager.shutdown(shutdown_timeout).await {
+        Ok(elapsed) => {
+            info!(
+                remaining = format!("{:.2?}", shutdown_timeout - elapsed),
+                "graceful shutdown complete"
+            );
+            current_exit_code
+        }
+        Err(pending_services) => {
+            warn!(
+                pending_count = pending_services.len(),
+                pending_services = ?pending_services,
+                "graceful shutdown elapsed - {} service(s) did not complete",
+                pending_services.len()
+            );
+
+            // Non-zero exit code, default to FAILURE if not set
+            if current_exit_code == ExitCode::SUCCESS {
+                ExitCode::FAILURE
+            } else {
+                current_exit_code
+            }
+        }
+    }
+}