refactor(server_lifecycle): Introduce graceful server shutdown and port management

Changes to entrypoint.sh:
- Implemented wait_for_ports_free function for ensuring ports are free before starting or restarting the server.
- Added constants for UDP and TCP ports, SHUTDOWN_TIMEOUT variable.
- Modified start_server() function to start the server gracefully with a timeout.
- Modified stop_server() function to gracefully stop the server, ask nicely first, and wait for it to finish before continuing. If the server does not stop within the specified time, it will be force killed.
- Added wait_for_ports_free after stopping the server to ensure ports are free before starting a new server instance or exiting the script.

These changes improve the server's graceful shutdown and port management for a smoother user experience.

Author: NekoSuneVR

entrypoint.sh

@@ -96,10 +96,27 @@ apply_env_to_config() {
 apply_env_to_config
 
 # -------------------------------------------------
-# Start / stop
+# Server lifecycle
 # -------------------------------------------------
 SERVER_PID=""
 
+UDP_PORT=2456
+TCP_PORT=2457
+SHUTDOWN_TIMEOUT=15
+
+wait_for_ports_free() {
+  echo "[VNyanNet] Waiting for ports to be released..."
+  for i in {1..20}; do
+    if ! ss -lunpt | grep -q ":$UDP_PORT" && ! ss -ltnp | grep -q ":$TCP_PORT"; then
+      echo "[VNyanNet] Ports are free"
+      return 0
+    fi
+    sleep 0.5
+  done
+
+  echo "⚠️ Ports still in use, continuing anyway"
+}
+
 start_server() {
   apply_env_to_config
   echo "[VNyanNet] Starting server..."
@@ -108,11 +125,36 @@ start_server() {
 }
 
 stop_server() {
-  if [[ -n "$SERVER_PID" ]] && kill -0 "$SERVER_PID" 2>/dev/null; then
-    echo "[VNyanNet] Stopping server (PID $SERVER_PID)"
-    kill "$SERVER_PID" 2>/dev/null || true
-    wait "$SERVER_PID" 2>/dev/null || true
+  if [[ -z "$SERVER_PID" ]]; then
+    return
+  fi
+
+  if ! kill -0 "$SERVER_PID" 2>/dev/null; then
+    return
   fi
+
+  echo "[VNyanNet] Gracefully stopping server (PID $SERVER_PID)"
+
+  # Ask nicely first
+  kill -TERM "$SERVER_PID" 2>/dev/null || true
+
+  for i in $(seq 1 "$SHUTDOWN_TIMEOUT"); do
+    if ! kill -0 "$SERVER_PID" 2>/dev/null; then
+      echo "[VNyanNet] Server stopped cleanly"
+      SERVER_PID=""
+      wait_for_ports_free
+      return
+    fi
+    sleep 1
+  done
+
+  # Force kill if needed
+  echo "⚠️ Server did not stop in time — force killing"
+  kill -KILL "$SERVER_PID" 2>/dev/null || true
+  wait "$SERVER_PID" 2>/dev/null || true
+  SERVER_PID=""
+
+  wait_for_ports_free
 }
 
 trap stop_server SIGINT SIGTERM
@@ -123,9 +165,12 @@ trap stop_server SIGINT SIGTERM
 start_server
 
 echo "[VNyanNet] Watching config for changes..."
+
 while true; do
-  inotifywait -e modify,close_write,move,create,delete "$CONFIG_FILE" >/dev/null 2>&1
+  inotifywait -e close_write "$CONFIG_FILE" >/dev/null 2>&1
+
   echo "[VNyanNet] Config changed — restarting server"
   stop_server
+  sleep 1
   start_server
 done