[3주차] 예약 API 구현 및 분산락 적용

README.md

@@ -458,12 +458,14 @@ Hibernate:
 
 # 예약 생성 API 추가
 ## 1. AOP 분산 락 적용 후
-![img_aop.png](doc/img_aop.png)
+![img.png](doc/img_aop.png)
 
 - 트랜잭션 실행 시간이 500ms ~ 750ms 으로 관찰됨
     - 이를 기반으로 leaseTime(잠금 유지 시간)을 실행 시간의 약 2배
     - waitTime(대기 시간)은 잠금 유지 시간의 2배로 설정
 - ⚠️ leaseTime 1.5초 + waitTime 3초 설정 시: 평균 응답 시간 9.68초
 - ✅ leaseTime 1초 + waitTime 2초 설정으로 변경: 평균 응답시간 `7.79초`로 감소
 
-## 2. 함수형 분산 락 적용 후
+## 2. 함수형 분산 락 적용 후
+![img.png](doc/img_functional.png)
+- 함수형 적용 후 평균 응답 시간(http_req_duration)이 AOP보다 약 20% 개선

movie-application/src/main/java/com/example/application/lock/DistributedLockExecutor.java

@@ -0,0 +1,7 @@
+package com.example.application.lock;
+
+import java.util.function.Supplier;
+
+public interface DistributedLockExecutor {
+    <T> T executeWithLock(String key, long waitTime, long leaseTime, Supplier<T> task);
+}

movie-application/src/main/java/com/example/application/lock/RedissonDistributedLockExecutor.java

@@ -0,0 +1,39 @@
+package com.example.application.lock;
+
+import java.util.concurrent.TimeUnit;
+import java.util.function.Supplier;
+import org.redisson.api.RLock;
+import org.redisson.api.RedissonClient;
+import org.springframework.stereotype.Component;
+
+@Component
+public class RedissonDistributedLockExecutor implements DistributedLockExecutor {
+
+    private final RedissonClient redissonClient;
+
+    public RedissonDistributedLockExecutor(RedissonClient redissonClient) {
+        this.redissonClient = redissonClient;
+    }
+
+    @Override
+    public <T> T executeWithLock(String key, long waitTime, long leaseTime, Supplier<T> task) {
+        RLock lock = redissonClient.getLock(key);
+        boolean acquired = false;
+
+        try {
+            acquired = lock.tryLock(waitTime, leaseTime, TimeUnit.MILLISECONDS);
+            if (!acquired) {
+                throw new IllegalStateException("[ERROR] Unable to acquire lock for key: " + key);
+            }
+            return task.get();
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            throw new RuntimeException("[ERROR] Lock acquisition interrupted", e);
+        } finally {
+            if (acquired) {
+                lock.unlock();
+            }
+        }
+    }
+
+}

movie-application/src/main/java/com/example/application/service/ReservationService.java

@@ -2,7 +2,7 @@
 
 import com.example.application.dto.request.ReservationRequestDto;
 import com.example.application.dto.response.ReservationResponseDto;
-import com.example.application.lock.DistributedLock;
+import com.example.application.lock.DistributedLockExecutor;
 import com.example.application.port.in.MessageServicePort;
 import com.example.application.port.in.ReservationServicePort;
 import com.example.application.port.out.MemberRepositoryPort;
@@ -20,11 +20,15 @@
 import com.example.domain.model.entity.ScreeningSeat;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Supplier;
 import java.util.stream.Collectors;
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.hibernate.exception.LockAcquisitionException;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
+@Slf4j
 @RequiredArgsConstructor
 @Service
 public class ReservationService implements ReservationServicePort {
@@ -38,8 +42,8 @@ public class ReservationService implements ReservationServicePort {
     private final ReservationValidationPort reservationValidationPort;
 
     private final MessageServicePort messageServicePort;
+    private final DistributedLockExecutor distributedLockExecutor;
 
-    @DistributedLock(key = "'seat_reservation:' + #request.screeningId + ':' + #request.seatIds.toString()")
     @Transactional
     @Override
     public ReservationResponseDto create(ReservationRequestDto request) {
@@ -48,10 +52,21 @@ public ReservationResponseDto create(ReservationRequestDto request) {
 
         List<ScreeningSeat> requestedSeats = validateReservationConstraints(screening, member, request.seatIds());
 
-        Reservation reservation = saveReservationAndSeats(screening, member, requestedSeats);
-        sendReservationConfirmation(member, requestedSeats, screening);
-
-        return ReservationResponseDto.fromEntity(reservation);
+        // 함수형 분산 락을 특정 메서드에 적용
+        String lockKey = "seat_reservation:" + request.screeningId() + ":" + request.seatIds();
+        long waitTime = 2000;
+        long leaseTime = 1000;
+
+        try {
+            return distributedLockExecutor.executeWithLock(lockKey, waitTime, leaseTime,
+                    () -> {
+                        Reservation reservation = saveReservationAndSeats(screening, member, requestedSeats);
+                        return ReservationResponseDto.fromEntity(reservation);
+                    });
+        } catch (LockAcquisitionException e) {
+            log.warn("[락 실패] 좌석 예약에 대한 락을 획득하지 못함 - Key: {}", lockKey);
+            throw new CustomException(ErrorCode.LOCK_ACQUISITION_FAILED, "좌석 예약 요청이 많아 처리가 지연되었습니다. 다시 시도해주세요.");
+        }
     }
 
     /** 상영 정보 조회 */
@@ -112,4 +127,5 @@ private void sendReservationConfirmation(Member member, List<ScreeningSeat> requ
                 requestedSeats.stream().map(ss -> ss.getSeat().getSeatNumber().toString()).collect(Collectors.joining(", ")),
                 screening.getMovie().getTitle(), screening.getTheater().getName(), screening.getStartTime()));
     }
+
 }

movie-domain/src/main/java/com/example/domain/exception/ErrorCode.java

@@ -24,6 +24,8 @@ public enum ErrorCode {
     SEATS_NOT_CONSECUTIVE("Seats must be consecutive in the same row.", 400),
     DUPLICATE_SEAT_REQUEST("Duplicate seat reservations are not allowed.", 400),
     INVALID_REQUEST("Invalid request.", 400),
+
+    LOCK_ACQUISITION_FAILED("Lock acquisition failed.", 400),
     ;
 
     private final String message;