[Volume 5] 상품 목록 조회 성능, 좋아요 수 정렬 구조 개선 및 인덱스·캐시 적용

.gitignore

@@ -42,3 +42,4 @@ out/
 ### Claude Code ###
 *.md
 !docs/**/*.md
+!blog/**/*.md

apps/commerce-api/build.gradle.kts

@@ -6,6 +6,9 @@ dependencies {
     implementation(project(":supports:logging"))
     implementation(project(":supports:monitoring"))
 
+    // cache
+    implementation("com.github.ben-manes.caffeine:caffeine")
+
     // web
     implementation("org.springframework.boot:spring-boot-starter-web")
     implementation("org.springframework.boot:spring-boot-starter-validation")

apps/commerce-api/src/main/java/com/loopers/application/like/LikeFacade.java

@@ -30,6 +30,7 @@ public void addLike(Long memberId, Long productId) {
         }
 
         likeRepository.save(new Like(memberId, productId));
+        productRepository.incrementLikeCount(productId);
     }
 
     @Transactional
@@ -40,6 +41,7 @@ public void removeLike(Long memberId, Long productId) {
         }
 
         likeRepository.delete(likeOpt.get());
+        productRepository.decrementLikeCount(productId);
     }
 
     public List<Like> getLikesByMemberId(Long memberId) {

apps/commerce-api/src/main/java/com/loopers/application/product/ProductCachePort.java

@@ -0,0 +1,22 @@
+package com.loopers.application.product;
+
+import com.loopers.interfaces.api.product.ProductDto;
+
+public interface ProductCachePort {
+
+    // ── 상품 상세 캐시 ──
+
+    ProductDto.ProductResponse getProductDetail(Long productId);
+
+    void putProductDetail(Long productId, ProductDto.ProductResponse response);
+
+    void evictProductDetail(Long productId);
+
+    // ── 상품 목록 캐시 ──
+
+    ProductDto.PagedProductResponse getProductList(Long brandId, String sort, int page, int size);
+
+    void putProductList(Long brandId, String sort, int page, int size, ProductDto.PagedProductResponse response);
+
+    void evictProductList();
+}

apps/commerce-api/src/main/java/com/loopers/application/product/ProductFacade.java

@@ -8,9 +8,13 @@
 import com.loopers.domain.product.vo.Stock;
 import com.loopers.domain.brand.Brand;
 import com.loopers.domain.brand.BrandRepository;
+import com.loopers.interfaces.api.product.ProductDto;
 import com.loopers.support.error.CoreException;
 import com.loopers.support.error.ErrorType;
 import lombok.RequiredArgsConstructor;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -26,21 +30,80 @@ public class ProductFacade {
     private final ProductRepository productRepository;
     private final BrandRepository brandRepository;
     private final LikeRepository likeRepository;
+    private final ProductCachePort productCachePort;
+
+    // ── 상품 상세 (캐시 적용) ──
 
     public ProductWithBrand getProductDetail(Long productId) {
         Product product = productRepository.findById(productId)
             .orElseThrow(() -> new CoreException(ErrorType.NOT_FOUND, "상품을 찾을 수 없습니다."));
         Brand brand = brandRepository.findById(product.getBrandId()).orElse(null);
         String brandName = (brand != null) ? brand.getName() : null;
-        long likeCount = likeRepository.countByProductId(productId);
-        return new ProductWithBrand(product, brandName, likeCount);
+        return new ProductWithBrand(product, brandName, product.getLikeCount());
+    }
+
+    public ProductDto.ProductResponse getProductDetailCached(Long productId) {
+        ProductDto.ProductResponse cached = productCachePort.getProductDetail(productId);
+        if (cached != null) {
+            return cached;
+        }
+
+        ProductWithBrand info = getProductDetail(productId);
+        ProductDto.ProductResponse response = ProductDto.ProductResponse.from(info);
+        productCachePort.putProductDetail(productId, response);
+        return response;
+    }
+
+    // ── 상품 목록 (페이지네이션 + 캐시 적용) ──
+
+    public Page<ProductWithBrand> getAllProducts(String sort, Pageable pageable) {
+        return productRepository.findAllWithBrand(sort, pageable);
+    }
+
+    public Page<ProductWithBrand> getProductsByBrandId(Long brandId, String sort, Pageable pageable) {
+        brandRepository.findById(brandId)
+            .orElseThrow(() -> new CoreException(ErrorType.NOT_FOUND, "브랜드를 찾을 수 없습니다."));
+        return productRepository.findAllByBrandIdWithBrand(brandId, sort, pageable);
+    }
+
+    public ProductDto.PagedProductResponse getAllProductsCached(Long brandId, String sort, int page, int size) {
+        ProductDto.PagedProductResponse cached = productCachePort.getProductList(brandId, sort, page, size);
+        if (cached != null) {
+            return cached;
+        }
+
+        Pageable pageable = PageRequest.of(page, size);
+        Page<ProductWithBrand> result;
+        if (brandId != null) {
+            result = getProductsByBrandId(brandId, sort, pageable);
+        } else {
+            result = getAllProducts(sort, pageable);
+        }
+
+        ProductDto.PagedProductResponse response = ProductDto.PagedProductResponse.from(result);
+        productCachePort.putProductList(brandId, sort, page, size, response);
+        return response;
     }
 
+    // ── 기존 List 반환 메서드 (하위 호환 + 벤치마크용) ──
+
     public List<ProductWithBrand> getAllProducts() {
-        return enrichWithLikeCount(productRepository.findAllWithBrand());
+        return productRepository.findAllWithBrand();
     }
 
     public List<ProductWithBrand> getAllProducts(String sort) {
+        return productRepository.findAllWithBrand(sort);
+    }
+
+    public List<ProductWithBrand> getProductsByBrandId(Long brandId) {
+        brandRepository.findById(brandId)
+            .orElseThrow(() -> new CoreException(ErrorType.NOT_FOUND, "브랜드를 찾을 수 없습니다."));
+        return productRepository.findAllByBrandIdWithBrand(brandId);
+    }
+
+    // ── 벤치마크 전용: AS-IS 재현 (enrichWithLikeCount + in-memory sort) ──
+
+    public List<ProductWithBrand> getAllProductsNoOptimization(String sort) {
         List<ProductWithBrand> results = enrichWithLikeCount(
             productRepository.findAllWithBrand(sort));
 
@@ -52,18 +115,16 @@ public List<ProductWithBrand> getAllProducts(String sort) {
         return results;
     }
 
-    public List<ProductWithBrand> getProductsByBrandId(Long brandId) {
-        brandRepository.findById(brandId)
-            .orElseThrow(() -> new CoreException(ErrorType.NOT_FOUND, "브랜드를 찾을 수 없습니다."));
-        return enrichWithLikeCount(productRepository.findAllByBrandIdWithBrand(brandId));
-    }
+    // ── 상품 CUD (캐시 무효화 포함) ──
 
     @Transactional
     public Product createProduct(Long brandId, String name, int price, int stockQuantity) {
         brandRepository.findById(brandId)
             .orElseThrow(() -> new CoreException(ErrorType.NOT_FOUND, "브랜드를 찾을 수 없습니다."));
         Product product = new Product(brandId, name, new Price(price), new Stock(stockQuantity));
-        return productRepository.save(product);
+        Product saved = productRepository.save(product);
+        productCachePort.evictProductList();
+        return saved;
     }
 
     @Transactional
@@ -73,6 +134,8 @@ public Product updateProduct(Long productId, String name, int price, int stockQu
         product.changeName(name);
         product.changePrice(new Price(price));
         product.changeStock(new Stock(stockQuantity));
+        productCachePort.evictProductDetail(productId);
+        productCachePort.evictProductList();
         return product;
     }
 
@@ -82,8 +145,12 @@ public void deleteProduct(Long productId) {
             .orElseThrow(() -> new CoreException(ErrorType.NOT_FOUND, "상품을 찾을 수 없습니다."));
         likeRepository.deleteAllByProductId(productId);
         product.delete();
+        productCachePort.evictProductDetail(productId);
+        productCachePort.evictProductList();
     }
 
+    // ── private: 벤치마크 전용 AS-IS 로직 보존 ──
+
     private List<ProductWithBrand> enrichWithLikeCount(List<ProductWithBrand> products) {
         List<Long> productIds = products.stream()
             .map(pwb -> pwb.product().getId())

apps/commerce-api/src/main/java/com/loopers/domain/like/Like.java

@@ -10,6 +10,8 @@
 @Entity
 @Table(name = "likes", uniqueConstraints = {
     @UniqueConstraint(name = "uk_likes_member_product", columnNames = {"member_id", "product_id"})
+}, indexes = {
+    @Index(name = "idx_likes_product_id", columnList = "product_id")
 })
 @Getter
 @NoArgsConstructor(access = AccessLevel.PROTECTED)

apps/commerce-api/src/main/java/com/loopers/domain/product/Product.java

@@ -10,7 +10,10 @@
 
 @Entity
 @Table(name = "product", indexes = {
-    @Index(name = "idx_product_brand_id", columnList = "brand_id")
+    @Index(name = "idx_product_brand_id", columnList = "brand_id"),
+    @Index(name = "idx_product_like_count", columnList = "like_count DESC, id DESC"),
+    @Index(name = "idx_product_brand_like_count", columnList = "brand_id, like_count DESC, id DESC"),
+    @Index(name = "idx_product_brand_price", columnList = "brand_id, price ASC, id ASC")
 })
 @Getter
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
@@ -28,6 +31,9 @@ public class Product extends BaseEntity {
     @Embedded
     private Stock stock;
 
+    @Column(name = "like_count", nullable = false)
+    private int likeCount = 0;
+
     public Product(Long brandId, String name, Price price, Stock stock) {
         this.brandId = brandId;
         this.name = name;

apps/commerce-api/src/main/java/com/loopers/domain/product/ProductLikeStats.java

@@ -0,0 +1,39 @@
+package com.loopers.domain.product;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.time.ZonedDateTime;
+
+@Entity
+@Table(name = "product_like_stats")
+@Getter
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+public class ProductLikeStats {
+
+    @Id
+    @Column(name = "product_id")
+    private Long productId;
+
+    @Column(name = "like_count", nullable = false)
+    private int likeCount;
+
+    @Column(name = "synced_at", nullable = false)
+    private ZonedDateTime syncedAt;
+
+    public ProductLikeStats(Long productId, int likeCount) {
+        this.productId = productId;
+        this.likeCount = likeCount;
+        this.syncedAt = ZonedDateTime.now();
+    }
+
+    public void updateCount(int likeCount) {
+        this.likeCount = likeCount;
+        this.syncedAt = ZonedDateTime.now();
+    }
+}

apps/commerce-api/src/main/java/com/loopers/domain/product/ProductLikeStatsRepository.java

@@ -0,0 +1,11 @@
+package com.loopers.domain.product;
+
+import java.util.List;
+
+public interface ProductLikeStatsRepository {
+    ProductLikeStats save(ProductLikeStats stats);
+    List<ProductLikeStats> saveAll(List<ProductLikeStats> statsList);
+    List<ProductLikeStats> findAll();
+    void syncAllFromLikes();
+    int correctProductLikeCounts();
+}

apps/commerce-api/src/main/java/com/loopers/domain/product/ProductRepository.java

@@ -1,5 +1,8 @@
 package com.loopers.domain.product;
 
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+
 import java.util.List;
 import java.util.Optional;
 
@@ -14,4 +17,12 @@ public interface ProductRepository {
     List<ProductWithBrand> findAllWithBrand();
     List<ProductWithBrand> findAllWithBrand(String sort);
     List<ProductWithBrand> findAllByBrandIdWithBrand(Long brandId);
+
+    // 페이지네이션 조회 (Brand JOIN)
+    Page<ProductWithBrand> findAllWithBrand(String sort, Pageable pageable);
+    Page<ProductWithBrand> findAllByBrandIdWithBrand(Long brandId, String sort, Pageable pageable);
+
+    // likeCount atomic 증감 (엔티티 로딩 없이 SQL 직접 실행)
+    int incrementLikeCount(Long productId);
+    int decrementLikeCount(Long productId);
 }

apps/commerce-api/src/main/java/com/loopers/infrastructure/product/CaffeineProductCacheAdapter.java

@@ -0,0 +1,66 @@
+package com.loopers.infrastructure.product;
+
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
+import com.loopers.application.product.ProductCachePort;
+import com.loopers.interfaces.api.product.ProductDto;
+import org.springframework.stereotype.Component;
+
+import java.time.Duration;
+
+@Component
+public class CaffeineProductCacheAdapter implements ProductCachePort {
+
+    private final Cache<String, ProductDto.ProductResponse> detailCache;
+    private final Cache<String, ProductDto.PagedProductResponse> listCache;
+
+    public CaffeineProductCacheAdapter() {
+        this.detailCache = Caffeine.newBuilder()
+            .maximumSize(500)
+            .expireAfterWrite(Duration.ofSeconds(30))
+            .build();
+        this.listCache = Caffeine.newBuilder()
+            .maximumSize(200)
+            .expireAfterWrite(Duration.ofSeconds(15))
+            .build();
+    }
+
+    @Override
+    public ProductDto.ProductResponse getProductDetail(Long productId) {
+        return detailCache.getIfPresent(detailKey(productId));
+    }
+
+    @Override
+    public void putProductDetail(Long productId, ProductDto.ProductResponse response) {
+        detailCache.put(detailKey(productId), response);
+    }
+
+    @Override
+    public void evictProductDetail(Long productId) {
+        detailCache.invalidate(detailKey(productId));
+    }
+
+    @Override
+    public ProductDto.PagedProductResponse getProductList(Long brandId, String sort, int page, int size) {
+        return listCache.getIfPresent(listKey(brandId, sort, page, size));
+    }
+
+    @Override
+    public void putProductList(Long brandId, String sort, int page, int size, ProductDto.PagedProductResponse response) {
+        listCache.put(listKey(brandId, sort, page, size), response);
+    }
+
+    @Override
+    public void evictProductList() {
+        listCache.invalidateAll();
+    }
+
+    private String detailKey(Long productId) {
+        return "detail:" + productId;
+    }
+
+    private String listKey(Long brandId, String sort, int page, int size) {
+        String brandPart = brandId != null ? String.valueOf(brandId) : "all";
+        return "list:brand:" + brandPart + ":sort:" + sort + ":page:" + page + ":size:" + size;
+    }
+}