[FEAT] 쿠폰 API 구현 - 비관적 락, 낙관적 락

src/main/java/com/example/book_your_seat/coupon/CouponConst.java

@@ -0,0 +1,10 @@
+package com.example.book_your_seat.coupon;
+
+public final class CouponConst {
+    public static final String INVALID_COUPON_AMOUNT = "쿠폰 수량은 0개 이상이어야 합니다.";
+    public static final String INVALID_COUPON_ID = "일치하는 쿠폰이 없습니다! Id: ";
+    public static final String DUPLICATE_BAD_REQUEST = "선착순 쿠폰은 중복 발급 받을 수 없습니다.";
+    public static final String COUPON_OUT_OF_STOCK = "쿠폰이 모두 소진되었습니다.";
+
+    private CouponConst() {}
+}

src/main/java/com/example/book_your_seat/coupon/controller/CouponController.java

@@ -0,0 +1,50 @@
+package com.example.book_your_seat.coupon.controller;
+
+import com.example.book_your_seat.coupon.controller.dto.CouponCreateRequest;
+import com.example.book_your_seat.coupon.controller.dto.CouponIdResponse;
+import com.example.book_your_seat.coupon.controller.dto.UserCouponResponse;
+import com.example.book_your_seat.coupon.service.CouponCommandService;
+import com.example.book_your_seat.coupon.service.CouponQueryService;
+import com.example.book_your_seat.user.domain.User;
+import jakarta.validation.Valid;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+import static com.example.book_your_seat.common.SessionConst.LOGIN_USER;
+
+@RequiredArgsConstructor
+@RequestMapping("/api/v1/coupons")
+@RestController
+public class CouponController {
+
+    private final CouponCommandService couponCommandService;
+    private final CouponQueryService couponQueryService;
+
+    /**
+     * 쿠폰 생성 (추후 관리자 권한 추가)
+     * @param couponCreateRequest{amount, discountRate}
+     * @return couponResponse{couponId}
+     */
+    @PostMapping
+    public ResponseEntity<CouponIdResponse> createCoupon(@RequestBody @Valid CouponCreateRequest couponCreateRequest) {
+        return ResponseEntity
+                .status(HttpStatus.CREATED)
+                .body(couponCommandService.createCoupon(couponCreateRequest));
+    }
+
+    /**
+     * 내 쿠폰 목록 조회
+     * @param user
+     * @return List<UserCouponResponse{userCouponId, discountRate, expirationDate, isUsed}>
+     */
+    @GetMapping("/my")
+    public ResponseEntity<List<UserCouponResponse>> getUserCoupons(@SessionAttribute(LOGIN_USER) User user) {
+        return ResponseEntity.ok()
+                .body(couponQueryService.getUserCoupons(user));
+    }
+
+}

src/main/java/com/example/book_your_seat/coupon/controller/dto/CouponCreateRequest.java

@@ -0,0 +1,24 @@
+package com.example.book_your_seat.coupon.controller.dto;
+
+import com.example.book_your_seat.coupon.domain.DiscountRate;
+import jakarta.validation.constraints.Future;
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotNull;
+
+import java.time.LocalDate;
+
+import static com.example.book_your_seat.coupon.CouponConst.INVALID_COUPON_AMOUNT;
+
+public record CouponCreateRequest(
+        @NotNull
+        @Min(value = 0, message = INVALID_COUPON_AMOUNT)
+        int amount,
+
+        @NotNull
+        DiscountRate discountRate,
+
+        @NotNull
+        @Future
+        LocalDate expirationDate
+) {
+}

src/main/java/com/example/book_your_seat/coupon/controller/dto/CouponIdResponse.java

@@ -0,0 +1,6 @@
+package com.example.book_your_seat.coupon.controller.dto;
+
+public record CouponIdResponse (
+        Long couponId
+) {
+}

src/main/java/com/example/book_your_seat/coupon/controller/dto/UserCouponIdResponse.java

@@ -0,0 +1,6 @@
+package com.example.book_your_seat.coupon.controller.dto;
+
+public record UserCouponIdResponse(
+        Long userCouponId
+) {
+}

src/main/java/com/example/book_your_seat/coupon/controller/dto/UserCouponResponse.java

@@ -0,0 +1,13 @@
+package com.example.book_your_seat.coupon.controller.dto;
+
+import com.example.book_your_seat.coupon.domain.DiscountRate;
+
+import java.time.LocalDate;
+
+public record UserCouponResponse(
+        Long userCouponId,
+        DiscountRate discountRate,
+        LocalDate expirationDate,
+        Boolean isUsed
+) {
+}

src/main/java/com/example/book_your_seat/coupon/domain/Coupon.java

@@ -1,21 +1,15 @@
 package com.example.book_your_seat.coupon.domain;
 
 import com.example.book_your_seat.common.entity.BaseEntity;
-import jakarta.persistence.CascadeType;
-import jakarta.persistence.Column;
-import jakarta.persistence.Entity;
-import jakarta.persistence.EnumType;
-import jakarta.persistence.Enumerated;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
-import jakarta.persistence.OneToMany;
-import java.util.ArrayList;
-import java.util.List;
+import jakarta.persistence.*;
 import lombok.AccessLevel;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
 
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.List;
+
 @Entity
 @Getter
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
@@ -30,15 +24,30 @@ public class Coupon extends BaseEntity {
     @Enumerated(EnumType.STRING)
     private DiscountRate discountRate;
 
+    private LocalDate expirationDate;
+
     @OneToMany(mappedBy = "coupon", cascade = CascadeType.ALL)
     private final List<UserCoupon> userCoupons = new ArrayList<>();
 
-    public Coupon(int amount, DiscountRate discountRate) {
+    //낙관적 락을 위한 버전
+    @Version
+    private Long version;
+
+    public Coupon(int amount, DiscountRate discountRate, LocalDate expirationDate) {
         this.amount = amount;
         this.discountRate = discountRate;
+        this.expirationDate = expirationDate;
+    }
+
+    public boolean noAmount() {
+        return this.amount <= 0;
     }
 
     public void addUserCoupon(UserCoupon userCoupon) {
         this.userCoupons.add(userCoupon);
     }
+
+    public void decreaseAmount() {
+        this.amount -= 1;
+    }
 }

src/main/java/com/example/book_your_seat/coupon/domain/UserCoupon.java

@@ -31,9 +31,12 @@ public class UserCoupon extends BaseEntity {
     @JoinColumn(name = "coupon_id")
     private Coupon coupon;
 
+    private boolean isUsed;
+
     public UserCoupon(User user, Coupon coupon) {
         this.user = user;
         this.coupon = coupon;
+        this.isUsed = false;
         user.adduserCoupon(this);
         coupon.addUserCoupon(this);
     }

src/main/java/com/example/book_your_seat/coupon/facade/OptimisticLockCouponFacade.java

@@ -0,0 +1,25 @@
+package com.example.book_your_seat.coupon.facade;
+
+import com.example.book_your_seat.coupon.service.CouponCommandService;
+import com.example.book_your_seat.user.domain.User;
+import lombok.RequiredArgsConstructor;
+import org.springframework.orm.ObjectOptimisticLockingFailureException;
+import org.springframework.stereotype.Service;
+
+@Service
+@RequiredArgsConstructor
+public class OptimisticLockCouponFacade {
+
+    private final CouponCommandService couponCommandService;
+
+    public void issueCouponWithOptimistic(User user, Long couponId) throws InterruptedException {
+        while(true) {
+            try {
+                couponCommandService.issueCouponWithOptimistic(user, couponId);
+                break;
+            } catch (ObjectOptimisticLockingFailureException e) {
+                Thread.sleep(50);
+            }
+        }
+    }
+}

src/main/java/com/example/book_your_seat/coupon/repository/CouponRepository.java

@@ -1,7 +1,20 @@
 package com.example.book_your_seat.coupon.repository;
 
 import com.example.book_your_seat.coupon.domain.Coupon;
+import jakarta.persistence.LockModeType;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Lock;
+import org.springframework.data.jpa.repository.Query;
+
+import java.util.Optional;
 
 public interface CouponRepository extends JpaRepository<Coupon, Long> {
+
+    @Lock(LockModeType.PESSIMISTIC_WRITE)
+    @Query("SELECT c FROM Coupon c WHERE c.id = :couponId")
+    Optional<Coupon> findByIdWithPessimistic(Long couponId);
+
+    @Lock(LockModeType.OPTIMISTIC)
+    @Query("SELECT c FROM Coupon c WHERE c.id = :couponId")
+    Optional<Coupon> findByIdWithOptimistic(Long couponId);
 }

src/main/java/com/example/book_your_seat/coupon/repository/UserCouponRepository.java

@@ -1,7 +1,19 @@
 package com.example.book_your_seat.coupon.repository;
 
 import com.example.book_your_seat.coupon.domain.UserCoupon;
+import com.example.book_your_seat.user.domain.User;
+import jakarta.persistence.LockModeType;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Lock;
+import org.springframework.data.jpa.repository.Query;
+
+import java.util.List;
+import java.util.Optional;
 
 public interface UserCouponRepository extends JpaRepository<UserCoupon, Long> {
+    @Lock(LockModeType.PESSIMISTIC_WRITE)
+    Optional<UserCoupon> findByUserIdAndCouponId(Long userId, Long couponId);
+
+    @Query("SELECT uc FROM UserCoupon uc JOIN FETCH uc.coupon WHERE uc.user = :user")
+    List<UserCoupon> findAllByUser(User user);
 }

src/main/java/com/example/book_your_seat/coupon/service/CouponCommandService.java

@@ -0,0 +1,13 @@
+package com.example.book_your_seat.coupon.service;
+
+import com.example.book_your_seat.coupon.controller.dto.CouponCreateRequest;
+import com.example.book_your_seat.coupon.controller.dto.CouponIdResponse;
+import com.example.book_your_seat.coupon.controller.dto.UserCouponIdResponse;
+import com.example.book_your_seat.user.domain.User;
+
+public interface CouponCommandService {
+    UserCouponIdResponse issueCouponWithPessimistic(User user, Long couponId);
+    UserCouponIdResponse issueCouponWithOptimistic(User user, Long couponId);
+    CouponIdResponse createCoupon(CouponCreateRequest couponCreateRequest);
+
+}

src/main/java/com/example/book_your_seat/coupon/service/CouponCommandServiceImpl.java

@@ -0,0 +1,90 @@
+package com.example.book_your_seat.coupon.service;
+
+import com.example.book_your_seat.coupon.controller.dto.CouponCreateRequest;
+import com.example.book_your_seat.coupon.controller.dto.CouponIdResponse;
+import com.example.book_your_seat.coupon.domain.Coupon;
+import com.example.book_your_seat.coupon.domain.UserCoupon;
+import com.example.book_your_seat.coupon.controller.dto.UserCouponIdResponse;
+import com.example.book_your_seat.coupon.repository.CouponRepository;
+import com.example.book_your_seat.coupon.repository.UserCouponRepository;
+import com.example.book_your_seat.user.domain.User;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import static com.example.book_your_seat.coupon.CouponConst.COUPON_OUT_OF_STOCK;
+import static com.example.book_your_seat.coupon.CouponConst.DUPLICATE_BAD_REQUEST;
+
+@Service
+@Transactional
+@RequiredArgsConstructor
+public class CouponCommandServiceImpl implements CouponCommandService {
+
+    private final CouponRepository couponRepository;
+    private final UserCouponRepository userCouponRepository;
+    private final CouponQueryService couponQueryService;
+
+    /*
+    쿠폰 발급 - 비관적 락
+     */
+    @Override
+    public UserCouponIdResponse issueCouponWithPessimistic(User user, Long couponId) {
+
+        Coupon coupon = couponQueryService.findByIdWithPessimistic(couponId);
+
+        //선착순 쿠폰 중복수령 방지
+        checkDuplicate(user.getId(), couponId);
+
+        //수량 체크
+        if(coupon.noAmount()) {
+            throw new IllegalArgumentException(COUPON_OUT_OF_STOCK);
+        }
+
+        coupon.decreaseAmount();
+
+        return new UserCouponIdResponse(
+                userCouponRepository.save(new UserCoupon(user, coupon)).getId()
+        );
+    }
+
+    /*
+    쿠폰 발급 - 낙관적 락
+    */
+    @Override
+    public UserCouponIdResponse issueCouponWithOptimistic(User user, Long couponId) {
+
+        Coupon coupon = couponQueryService.findByIdWithOptimistic(couponId);
+
+        //선착순 쿠폰 중복수령 방지
+        checkDuplicate(user.getId(), couponId);
+
+        //수량 체크
+        if(coupon.noAmount()) {
+            throw new IllegalArgumentException(COUPON_OUT_OF_STOCK);
+        }
+
+        coupon.decreaseAmount();
+
+        return new UserCouponIdResponse(
+                userCouponRepository.save(new UserCoupon(user, coupon)).getId()
+        );
+
+    }
+
+    /*
+    쿠폰 생성
+     */
+    @Override
+    public CouponIdResponse createCoupon(CouponCreateRequest request) {
+        return new CouponIdResponse(
+                couponRepository.save(new Coupon(request.amount(), request.discountRate(),request.expirationDate())).getId()
+        );
+    }
+
+    private void checkDuplicate(Long userId, Long couponId) {
+        userCouponRepository.findByUserIdAndCouponId(userId, couponId).ifPresent(userCoupon -> {
+                    throw new IllegalArgumentException(DUPLICATE_BAD_REQUEST);
+                }
+        );
+    }
+}

src/main/java/com/example/book_your_seat/coupon/service/CouponQueryService.java

@@ -0,0 +1,13 @@
+package com.example.book_your_seat.coupon.service;
+
+import com.example.book_your_seat.coupon.controller.dto.UserCouponResponse;
+import com.example.book_your_seat.coupon.domain.Coupon;
+import com.example.book_your_seat.user.domain.User;
+
+import java.util.List;
+
+public interface CouponQueryService {
+    Coupon findByIdWithPessimistic(Long couponId);
+    Coupon findByIdWithOptimistic(Long couponId);
+    List<UserCouponResponse> getUserCoupons(User user);
+}