[5주차] 낙관적락 분산락 적용

README.md

@@ -62,4 +62,21 @@ Reservation(예매)과 Seat(좌석)는 M:N 관계이므로 ReservedSeat 중간
 
 ## 성능측정
 
-[성능측정보고서 링크](https://kind-artichoke-34f.notion.site/180a4bf15f1a805eadc6c3bbc20f74a9?pvs=4)
+[성능측정보고서 링크](https://kind-artichoke-34f.notion.site/180a4bf15f1a805eadc6c3bbc20f74a9?pvs=4)
+
+## 분산락 leaseTime 및 waitTime 설정 값과 이유
+
+### 평균 소요 시간
+- 예매 API의 평균 소요 시간: 570ms
+
+### leaseTime 설정 값: 2초
+- 설정 이유
+  - leaseTime은 트랜잭션 수행 중 락이 유지되는 시간입니다.
+  - 570ms는 평균 수행 시간이므로, **예외 상황(예: 네트워크 지연, 서버 부하 등)**을 고려하여 여유 시간을 추가해야 합니다.
+  - 일반적으로 평균 수행 시간의 2배 ~ 3배를 설정하는 것이 적당하므로, 2초로 설정했습니다.
+
+### waitTime 설정 값: 2초
+- 설정 이유:
+  - waitTime은 다른 요청이 락을 점유하고 있을 때, 현재 요청이 락 해제를 기다릴 최대 시간입니다.
+  - 평균 트랜잭션 수행 시간이 570ms이므로, 락이 해제될 때까지 기다릴 충분한 시간이라고 판단하여 2초로 설정했습니다.
+  - 이를 통해 대부분의 트랜잭션이 락 해제를 기다릴 여유를 가질 수 있습니다.

application/src/main/java/com/example/aop/DistributedLock.java

@@ -10,7 +10,7 @@
 @Retention(RetentionPolicy.RUNTIME)
 public @interface DistributedLock {
     String key();
-    long leaseTime() default 5;
-    long waitTime() default 5;
+    long leaseTime() default 2;
+    long waitTime() default 2;
     TimeUnit timeUnit() default TimeUnit.SECONDS;
 }

application/src/main/java/com/example/func/DistributedLockExecutor.java

@@ -0,0 +1,45 @@
+package com.example.func;
+
+import lombok.RequiredArgsConstructor;
+import org.redisson.api.RLock;
+import org.redisson.api.RedissonClient;
+import org.springframework.stereotype.Component;
+
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Supplier;
+
+@Component
+@RequiredArgsConstructor
+public class DistributedLockExecutor {
+
+    private final RedissonClient redissonClient;
+
+    public <T> T executeWithLock(List<String> lockKeys, long waitTime, long leaseTime, TimeUnit timeUnit, Supplier<T> action) {
+        List<RLock> locks = lockKeys.stream()
+                .map(redissonClient::getLock)
+                .toList();
+        boolean allLocked = false;
+
+        try {
+            allLocked = redissonClient.getMultiLock(locks.toArray(new RLock[0]))
+                    .tryLock(waitTime, leaseTime, timeUnit);
+
+            if (!allLocked) {
+                throw new IllegalArgumentException("해당 좌석은 현재 다른 사용자가 예매를 진행하고 있습니다.");
+            }
+
+            return action.get();
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        } finally {
+            if (allLocked) {
+                locks.forEach(lock -> {
+                    if (lock.isHeldByCurrentThread()) {
+                        lock.unlock();
+                    }
+                });
+            }
+        }
+    }
+}

application/src/main/java/com/example/reservation/ReservationService.java

@@ -1,8 +1,8 @@
 package com.example.reservation;
 
-import com.example.aop.DistributedLock;
 import com.example.entity.reservation.Reservation;
 import com.example.entity.reservation.ReservedSeat;
+import com.example.func.DistributedLockExecutor;
 import com.example.message.MessageService;
 import com.example.repository.reservation.ReservationRepository;
 import com.example.reservation.request.ReservationServiceRequest;
@@ -14,6 +14,7 @@
 import org.springframework.transaction.annotation.Transactional;
 
 import java.util.List;
+import java.util.concurrent.TimeUnit;
 
 @Service
 @RequiredArgsConstructor
@@ -22,20 +23,27 @@ public class ReservationService {
     private final MessageService messageService;
     private final ReservationValidate reservationValidate;
     private final ReservationRepository reservationRepository;
+    private final DistributedLockExecutor lockExecutor;
 
+//    @DistributedLock(key = "reservation:screening:{#request.screeningId}:seat:{#request.seatIds}", leaseTime = 2, waitTime = 2)
     @Transactional
-    @DistributedLock(key = "reservation:screening:{#request.screeningId}:seat:{#request.seatIds}", leaseTime = 10, waitTime = 5)
     public ReservationServiceResponse reserve(ReservationServiceRequest request) {
 
-        ReservationValidationResult validationResult = reservationValidate.validate(request);
+        List<String> lockKeys = request.getSeatIds().stream()
+                .map(seatId -> "reservation:screening:" + request.getScreeningId() + ":seat:" + seatId)
+                .toList();
+
+        return lockExecutor.executeWithLock(lockKeys, 2, 2, TimeUnit.SECONDS, () -> {
+            ReservationValidationResult validationResult = reservationValidate.validate(request);
 
-        Reservation reservation = createReservation(validationResult);
+            Reservation reservation = createReservation(validationResult);
 
-        reservationRepository.save(reservation);
+            reservationRepository.save(reservation);
 
-        messageService.send();
+            messageService.send();
 
-        return ReservationServiceResponse.of(reservation);
+            return ReservationServiceResponse.of(reservation);
+        });
     }
 
     private Reservation createReservation(ReservationValidationResult validationResult) {

application/src/main/java/com/example/reservation/validator/ReservationValidate.java

@@ -10,6 +10,7 @@
 import com.example.repository.reservation.ReservedSeatRepository;
 import com.example.reservation.request.ReservationServiceRequest;
 import lombok.RequiredArgsConstructor;
+import org.redisson.api.RScript;
 import org.redisson.api.RedissonClient;
 import org.springframework.stereotype.Component;
 
@@ -84,33 +85,30 @@ private Seats getSeats(List<Long> seatsIds) {
         return new Seats(seatRepository.findAllById(seatsIds));
     }
 
-//    private void validateAndReserveSeatsInRedis(Long screeningId, List<Long> seatIds) {
-//        String redisKey = "screening:" + screeningId + ":seats";
-//
-//        // Lua 스크립트: 좌석 상태를 확인하고, 예약되지 않은 경우 예약 상태로 변경
-//        String luaScript =
-//                "for i, seatId in ipairs(ARGV) do " +
-//                        "   if redis.call('HGET', KEYS[1], seatId) == 'true' then " + // 이미 예약된 좌석 확인
-//                        "       return 0; " +
-//                        "   end; " +
-//                        "end; " +
-//                        "for i, seatId in ipairs(ARGV) do " +
-//                        "   redis.call('HSET', KEYS[1], seatId, 'true'); " + // 좌석 상태를 예약으로 변경
-//                        "end; " +
-//                        "return 1;";
-//
-//        // Redisson의 Lua 실행 API 호출
-//        Long result = redissonClient.getScript().eval(
-//                RScript.Mode.READ_WRITE,
-//                luaScript,
-//                RScript.ReturnType.INTEGER,
-//                List.of(redisKey), // Redis 키
-//                seatIds.stream().map(String::valueOf).toArray() // ARGV: 좌석 ID 리스트
-//        );
-//
-//        // Lua 스크립트 결과가 0이면 좌석 예약 실패 처리
-//        if (result == 0) {
-//            throw new IllegalArgumentException("이미 예매된 좌석입니다.");
-//        }
-//    }
+    private void validateAndReserveSeatsInRedis(Long screeningId, List<Long> seatIds) {
+        String redisKey = "screening:" + screeningId + ":seats";
+
+        String luaScript =
+                "for i, seatId in ipairs(ARGV) do " +
+                "   if redis.call('HGET', KEYS[1], seatId) == 'true' then " +
+                "       return 0; " +
+                "   end; " +
+                "end; " +
+                "for i, seatId in ipairs(ARGV) do " +
+                "   redis.call('HSET', KEYS[1], seatId, 'true'); " +
+                "end; " +
+                "return 1;";
+
+        Long result = redissonClient.getScript().eval(
+                RScript.Mode.READ_WRITE,
+                luaScript,
+                RScript.ReturnType.INTEGER,
+                List.of(redisKey),
+                seatIds.stream().map(String::valueOf).toArray()
+        );
+
+        if (result == 0) {
+            throw RESERVATION_EXIST_ERROR.exception();
+        }
+    }
 }