[Feature/be] 동시성으로 인한 데이터 정합성 문제 해결 (#790)

* [BE] 리뷰 작성 시 제품 통계 정보의 정합성을 맞추도록 수정 (#784)

* feat: 제품 통계 정합성 맞추는 쿼리 작성

* refactor: 서비스에서 제품 통계 업데이트를 쿼리를 직접 사용하도록 수정

* [BE] 데이터 정합성을 맞추는 스케줄러 작성 (#789)

* feat: 회원 팔로워 수의 데이터 정합성을 배치 처리하는 쿼리 작성

* refactor: 서비스 레이어에서 명시적 flush 대신 벌크 쿼리의 flushAutomatically 모드를 true로 설정

* feat: 1시간마다 회원의 팔로워 수 정합성을 맞추는 배치 쿼리를 실행하는 스케줄러 구현

* fix: 스케줄러가 테스트 환경에서는 빈으로 등록되지 않도록 수정

* [BE] 회원 정합성 문제 해결 배치 스케줄 대신 실시간으로 정합성을 맞추는 쿼리로 교체 (#809)

* feat: 팔로워 수를 증가 / 감소 시키는 쿼리 작성

* refactor: 더티 체킹 대신 팔로워 수 조작 쿼리를 사용하도록 수정

* fix: 불필요한 쿼리 및 객체 제거

* refactor: 코드리뷰 반영

backend/src/main/java/com/woowacourse/f12/application/member/MemberService.java

@@ -139,20 +139,19 @@ private List<Long> extractMemberIds(final List<Member> members) {
 
     @Transactional
     public void follow(final Long followerId, final Long followingId) {
-        final Member targetMember = memberRepository.findById(followingId)
-                .orElseThrow(MemberNotFoundException::new);
-        validateFollowingMembersExist(followerId);
+        validateMemberExists(followerId);
+        validateMemberExists(followingId);
         validateNotFollowing(followerId, followingId);
         final Following following = Following.builder()
                 .followerId(followerId)
                 .followingId(followingId)
                 .build();
         followingRepository.save(following);
-        targetMember.increaseFollowerCount();
+        memberRepository.increaseFollowerCount(followingId);
     }
 
-    private void validateFollowingMembersExist(final Long followerId) {
-        if (!memberRepository.existsById(followerId)) {
+    private void validateMemberExists(final Long memberId) {
+        if (!memberRepository.existsById(memberId)) {
             throw new MemberNotFoundException();
         }
     }
@@ -165,12 +164,11 @@ private void validateNotFollowing(final Long followerId, final Long followingId)
 
     @Transactional
     public void unfollow(final Long followerId, final Long followingId) {
-        final Member targetMember = memberRepository.findById(followingId)
-                .orElseThrow(MemberNotFoundException::new);
-        validateFollowingMembersExist(followerId);
+        validateMemberExists(followerId);
+        validateMemberExists(followingId);
         final Following following = findFollowingRelation(followerId, followingId);
         followingRepository.delete(following);
-        targetMember.decreaseFollowerCount();
+        memberRepository.decreaseFollowerCount(followingId);
     }
 
     private Following findFollowingRelation(final Long followerId, final Long followingId) {

backend/src/main/java/com/woowacourse/f12/application/review/ReviewService.java

@@ -52,6 +52,7 @@ public Long saveReviewAndInventoryProduct(final Long productId, final Long membe
                 .orElseThrow(ProductNotFoundException::new);
         final Long reviewId = saveReview(reviewRequest, member, product);
         saveInventoryProduct(member, product);
+        productRepository.updateProductStatisticsForReviewInsert(product.getId(), reviewRequest.getRating());
         return reviewId;
     }
 
@@ -64,7 +65,6 @@ private void validateRegisterCompleted(final Member member) {
     private Long saveReview(final ReviewRequest reviewRequest, final Member member, final Product product) {
         validateNotWritten(member, product);
         final Review review = reviewRequest.toReview(product, member);
-        review.reflectToProductWhenWritten();
         return reviewRepository.save(review)
                 .getId();
     }
@@ -111,18 +111,20 @@ public ReviewWithAuthorAndProductPageResponse findPage(final Pageable pageable)
     public void update(final Long reviewId, final Long memberId, final ReviewRequest updateRequest) {
         final Review target = findTarget(reviewId, memberId);
         final Review updateReview = updateRequest.toReview(target.getProduct(), target.getMember());
+        int ratingGap = updateReview.getRating() - target.getRating();
         target.update(updateReview);
+        productRepository.updateProductStatisticsForReviewUpdate(target.getProduct().getId(), ratingGap);
     }
 
     @Transactional
     public void delete(final Long reviewId, final Long memberId) {
         final Review review = findTarget(reviewId, memberId);
-        review.reflectToProductBeforeDelete();
-        reviewRepository.delete(review);
         final InventoryProduct inventoryProduct = inventoryProductRepository.findWithProductByMemberAndProduct(
                         review.getMember(), review.getProduct())
                 .orElseThrow(InventoryProductNotFoundException::new);
         inventoryProductRepository.delete(inventoryProduct);
+        reviewRepository.delete(review);
+        productRepository.updateProductStatisticsForReviewDelete(review.getProduct().getId(), review.getRating());
     }
 
     private Review findTarget(final Long reviewId, final Long memberId) {

backend/src/main/java/com/woowacourse/f12/domain/member/Member.java

@@ -2,7 +2,6 @@
 
 import com.woowacourse.f12.domain.inventoryproduct.InventoryProduct;
 import com.woowacourse.f12.domain.inventoryproduct.InventoryProducts;
-import com.woowacourse.f12.exception.badrequest.InvalidFollowerCountException;
 import java.util.List;
 import java.util.Objects;
 import javax.persistence.Column;
@@ -114,17 +113,6 @@ private void updateJobType(final JobType jobType) {
         }
     }
 
-    public void increaseFollowerCount() {
-        this.followerCount += 1;
-    }
-
-    public void decreaseFollowerCount() {
-        if (this.followerCount == 0) {
-            throw new InvalidFollowerCountException();
-        }
-        this.followerCount -= 1;
-    }
-
     private void updateRegistered(final boolean registered) {
         if (this.registered) {
             return;

backend/src/main/java/com/woowacourse/f12/domain/member/MemberRepository.java

@@ -2,8 +2,19 @@
 
 import java.util.Optional;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
 
 public interface MemberRepository extends JpaRepository<Member, Long>, MemberRepositoryCustom {
 
     Optional<Member> findByGitHubId(String gitHubId);
+
+    @Modifying(clearAutomatically = true, flushAutomatically = true)
+    @Query(value = "update Member m set m.followerCount = m.followerCount + 1 where m.id = :followingMemberId")
+    void increaseFollowerCount(Long followingMemberId);
+
+    @Modifying(clearAutomatically = true, flushAutomatically = true)
+    @Query(value = "update Member m set m.followerCount = case m.followerCount when 0 then 0 "
+            + "else (m.followerCount - 1) end where m.id = :followingMemberId")
+    void decreaseFollowerCount(Long followingMemberId);
 }

backend/src/main/java/com/woowacourse/f12/domain/product/ProductRepository.java

@@ -2,8 +2,34 @@
 
 import java.util.List;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
 
 public interface ProductRepository extends JpaRepository<Product, Long>, ProductRepositoryCustom {
 
     List<Product> findByReviewCountGreaterThanEqualAndRatingGreaterThanEqual(int reviewCount, double rating);
+
+    @Modifying(clearAutomatically = true, flushAutomatically = true)
+    @Query(value = "update Product p "
+            + "set p.rating = (p.totalRating + :reviewRating) / cast((p.reviewCount + 1) as double), "
+            + "p.reviewCount = p.reviewCount + 1, "
+            + "p.totalRating = p.totalRating + :reviewRating "
+            + "where p.id = :productId")
+    void updateProductStatisticsForReviewInsert(Long productId, int reviewRating);
+
+    @Modifying(clearAutomatically = true, flushAutomatically = true)
+    @Query(value = "update Product p "
+            + "set p.rating = case p.reviewCount when 1 then 0 "
+            + "else ((p.totalRating - :reviewRating) / cast((p.reviewCount - 1) as double)) end , "
+            + "p.reviewCount = p.reviewCount - 1, "
+            + "p.totalRating = p.totalRating - :reviewRating "
+            + "where p.id = :productId")
+    void updateProductStatisticsForReviewDelete(Long productId, int reviewRating);
+
+    @Modifying(clearAutomatically = true, flushAutomatically = true)
+    @Query(value = "update Product p "
+            + "set p.rating = (p.totalRating + :ratingGap) / cast(p.reviewCount as double), "
+            + "p.totalRating = p.totalRating + :ratingGap "
+            + "where p.id = :productId")
+    void updateProductStatisticsForReviewUpdate(Long productId, int ratingGap);
 }

backend/src/main/java/com/woowacourse/f12/domain/review/Review.java

@@ -88,25 +88,13 @@ private void validateRating(final int rating) {
         }
     }
 
-    public void reflectToProductWhenWritten() {
-        product.increaseReviewCount();
-        product.increaseRating(rating);
-    }
-
-    public void reflectToProductBeforeDelete() {
-        product.decreaseReviewCount();
-        product.decreaseRating(rating);
-    }
-
     public boolean isWrittenBy(final Member member) {
         return this.member.equals(member);
     }
 
     public void update(final Review updateReview) {
-        product.decreaseRating(rating);
         content = updateReview.getContent();
         rating = updateReview.getRating();
-        product.increaseRating(rating);
     }
 
     @Override

backend/src/main/java/com/woowacourse/f12/exception/ErrorCode.java

@@ -25,7 +25,6 @@ public enum ErrorCode {
     SELF_FOLLOW("40050"),
     ALREADY_FOLLOWING("40051"),
     NOT_FOLLOWING("40052"),
-    INVALID_FOLLOWER_COUNT("40053"),
 
     REQUEST_DUPLICATED("40060"),