Request → Filter(시작) → Controller → Service → Repository → Filter(종료+로그출력)
 ↓ ↓ ↓
 AOP가 각 단계 시간을 PerformanceContext에 누적

@Component
public class PerformanceContext {

 private static final ThreadLocal<List<StepRecord>> steps = 
 ThreadLocal.withInitial(ArrayList::new);
 private static final ThreadLocal<Long> requestStart = new ThreadLocal<>();

 public void startRequest() {
 steps.get().clear(); // 이전 요청 데이터 초기화
 requestStart.set(System.nanoTime());
 }

 public void record(String stepName, long elapsedMs) {
 steps.get().add(new StepRecord(stepName, elapsedMs));
 }

 public String buildSummary() {
 long totalMs = (System.nanoTime() - requestStart.get()) / 1_000_000;
 StringBuilder sb = new StringBuilder("\n==== API Performance Summary ====\n");

 for (StepRecord step : steps.get()) {
 sb.append(String.format(" %-40s %5dms\n", step.name(), step.elapsedMs()));
 }

 sb.append("---------------------------------\n");
 sb.append(String.format(" %-40s %5dms\n", "TOTAL", totalMs));
 sb.append("=================================");
 return sb.toString();
 }

 public void clear() {
 steps.remove();
 requestStart.remove();
 }

 public record StepRecord(String name, long elapsedMs) {}
}

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface TrackTime {
 String value() default ""; // 로그에 표시할 이름 (비어있으면 메서드명 사용)
}

@Aspect
@Component
@RequiredArgsConstructor
public class PerformanceAspect {

 private final PerformanceContext performanceContext;

 @Around("@annotation(trackTime)")
 public Object track(ProceedingJoinPoint joinPoint, TrackTime trackTime) throws Throwable {
 String stepName = trackTime.value().isBlank()
 ? joinPoint.getSignature().toShortString()
 : trackTime.value();

 long start = System.nanoTime();
 try {
 return joinPoint.proceed();
 } finally {
 long elapsed = (System.nanoTime() - start) / 1_000_000;
 performanceContext.record(stepName, elapsed);
 }
 }
}

@Component
@RequiredArgsConstructor
public class PerformanceFilter extends OncePerRequestFilter {

 private static final Logger log = LoggerFactory.getLogger(PerformanceFilter.class);
 private final PerformanceContext performanceContext;

 @Override
 protected void doFilterInternal(HttpServletRequest request,
 HttpServletResponse response,
 FilterChain filterChain) throws ServletException, IOException {
 performanceContext.startRequest();
 try {
 filterChain.doFilter(request, response);
 } finally {
 log.info("[{} {}]{}", 
 request.getMethod(), 
 request.getRequestURI(),
 performanceContext.buildSummary());
 performanceContext.clear(); // 반드시 ThreadLocal 정리
 }
 }
}

@RestController
@RequiredArgsConstructor
public class OrderController {

 private final OrderService orderService;

 @PostMapping("/api/orders")
 public ResponseEntity<OrderResponse> createOrder(@RequestBody OrderRequest request) {
 return ResponseEntity.ok(orderService.createOrder(request));
 }
}

@Service
@RequiredArgsConstructor
public class OrderService {

 private final UserService userService;
 private final ProductService productService;
 private final OrderRepository orderRepository;

 @TrackTime("1. 주문 처리 (Service)")
 public OrderResponse createOrder(OrderRequest request) {
 User user = userService.validateUser(request.getUserId());
 Product product = productService.checkStock(request.getProductId());
 return orderRepository.save(user, product);
 }
}

@Service
public class UserService {

 @TrackTime("2. 유저 검증 (UserService)")
 public User validateUser(Long userId) {
 // DB 조회, 권한 체크 등
 }
}

@Service
public class ProductService {

 @TrackTime("3. 재고 확인 (ProductService)")
 public Product checkStock(Long productId) {
 // 재고 조회
 }
}

@Repository
public class OrderRepository {

 @TrackTime("4. 주문 저장 (Repository)")
 public OrderResponse save(User user, Product product) {
 // INSERT 쿼리
 }
}

INFO [POST /api/orders]
==== API Performance Summary ====
 2. 유저 검증 (UserService) 12ms
 3. 재고 확인 (ProductService) 8ms
 4. 주문 저장 (Repository) 23ms
 1. 주문 처리 (Service) 48ms ← 하위 포함한 전체
---------------------------------
 TOTAL 51ms ← Filter 기준 전체
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