[volume-5] 인덱스와 캐시를 활용한 상품 조회 읽기 성능 최적화

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

@@ -5,6 +5,7 @@
 import com.loopers.domain.product.OptionRepository;
 import com.loopers.domain.product.Product;
 import com.loopers.domain.product.ProductRepository;
+import com.loopers.application.product.ProductCacheManager;
 import com.loopers.support.error.CoreException;
 import com.loopers.support.error.ErrorType;
 import lombok.RequiredArgsConstructor;
@@ -18,6 +19,7 @@
 public class AdminProductAppService {
     private final ProductRepository productRepository;
     private final OptionRepository optionRepository;
+    private final ProductCacheManager productCacheManager;
 
     @Transactional
     public Product create(Long brandId, String name, Money basePrice) {
@@ -36,6 +38,7 @@ public Option createOption(Long productId, String name, Money additionalPrice, i
     public Product update(Long id, String name, Money basePrice) {
         Product product = getById(id);
         product.update(name, basePrice);
+        productCacheManager.evictProductCaches(id, product.getBrandId());
         return product;
     }
 
@@ -44,6 +47,7 @@ public void delete(Long id) {
         Product product = getById(id);
         product.delete();
         deleteOptionsByProductId(id);
+        productCacheManager.evictProductCaches(id, product.getBrandId());
     }
 
     @Transactional

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

@@ -0,0 +1,38 @@
+package com.loopers.application.product;
+
+import com.loopers.domain.common.Money;
+import com.loopers.domain.product.Product;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.extern.jackson.Jacksonized;
+
+import java.util.List;
+
+@Getter
+@Builder
+@Jacksonized
+public class CachedBrandProductPage {
+    private final List<ProductSummary> content;
+    private final long totalElements;
+
+    @Getter
+    @Builder
+    @Jacksonized
+    public static class ProductSummary {
+        private final Long productId;
+        private final String productName;
+        private final Money basePrice;
+        private final boolean deleted;
+        private final long likeCount;
+
+        public static ProductSummary from(Product product) {
+            return ProductSummary.builder()
+                    .productId(product.getId())
+                    .productName(product.getName())
+                    .basePrice(product.getBasePrice())
+                    .deleted(product.isDeleted())
+                    .likeCount(product.getLikeCount())
+                    .build();
+        }
+    }
+}

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

@@ -0,0 +1,38 @@
+package com.loopers.application.product;
+
+import com.loopers.domain.common.Money;
+import com.loopers.domain.product.Option;
+import com.loopers.domain.product.Product;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.extern.jackson.Jacksonized;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+
+@Getter
+@Builder
+@Jacksonized
+public class CachedProductDetail {
+    private final Long productId;
+    private final String productName;
+    private final Money basePrice;
+    private final boolean deleted;
+    private final Long brandId;
+    private final long likeCount;
+    private final List<ProductInfo.OptionInfo> options;
+
+    public static CachedProductDetail from(Product product, List<Option> options, long likeCount) {
+        return CachedProductDetail.builder()
+                .productId(product.getId())
+                .productName(product.getName())
+                .basePrice(product.getBasePrice())
+                .deleted(product.isDeleted())
+                .brandId(product.getBrandId())
+                .likeCount(likeCount)
+                .options(Optional.ofNullable(options).orElseGet(Collections::emptyList)
+                        .stream().map(ProductInfo.OptionInfo::from).toList())
+                .build();
+    }
+}

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

@@ -9,19 +9,29 @@
 import com.loopers.support.error.CoreException;
 import com.loopers.support.error.ErrorType;
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+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;
 
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 
+@Slf4j
 @Service
 @RequiredArgsConstructor
 public class ProductAppService {
+    private static final int CACHEABLE_PAGE_LIMIT = 2;
+    private static final int MAX_PAGE_SIZE = 50;
+
     private final ProductRepository productRepository;
     private final OptionRepository optionRepository;
+    private final ProductCacheManager productCacheManager;
 
     @Transactional
     public Product create(Long brandId, String name, Money basePrice) {
@@ -40,6 +50,65 @@ public List<Product> getProducts(ProductSortCondition condition) {
         return productRepository.findAll(condition);
     }
 
+    @Transactional(readOnly = true)
+    public Page<Product> getProductsByBrandId(Long brandId, int page, int size) {
+        return productRepository.findByBrandIdWithPaging(brandId, validatedPageRequest(page, size));
+    }
+
+    @Transactional(readOnly = true)
+    public CachedProductDetail getProductDetailCached(Long productId) {
+        try {
+            Optional<CachedProductDetail> cached = productCacheManager.getProductDetail(productId);
+            if (cached.isPresent()) {
+                return cached.get();
+            }
+        } catch (Exception e) {
+            log.warn("캐시 조회 실패, DB fallback. productId={}", productId, e);
+        }
+
+        Product product = getById(productId);
+        List<Option> options = optionRepository.findByProductId(productId);
+        long likeCount = product.getLikeCount();
+
+        CachedProductDetail detail = CachedProductDetail.from(product, options, likeCount);
+        try {
+            productCacheManager.putProductDetail(productId, detail);
+        } catch (Exception e) {
+            log.warn("캐시 저장 실패. productId={}", productId, e);
+        }
+        return detail;
+    }
+
+    @Transactional(readOnly = true)
+    public CachedBrandProductPage getProductsByBrandIdCached(Long brandId, int page, int size) {
+        if (page <= CACHEABLE_PAGE_LIMIT) {
+            try {
+                Optional<CachedBrandProductPage> cached = productCacheManager.getProductList(brandId, page, size);
+                if (cached.isPresent()) {
+                    return cached.get();
+                }
+            } catch (Exception e) {
+                log.warn("캐시 조회 실패, DB fallback. brandId={}, page={}", brandId, page, e);
+            }
+        }
+
+        Page<Product> products = productRepository.findByBrandIdWithPaging(brandId, validatedPageRequest(page, size));
+        CachedBrandProductPage result = CachedBrandProductPage.builder()
+                .content(products.getContent().stream().map(CachedBrandProductPage.ProductSummary::from).toList())
+                .totalElements(products.getTotalElements())
+                .build();
+
+        if (page <= CACHEABLE_PAGE_LIMIT) {
+            try {
+                productCacheManager.putProductList(brandId, page, size, result);
+            } catch (Exception e) {
+                log.warn("캐시 저장 실패. brandId={}, page={}", brandId, page, e);
+            }
+        }
+
+        return result;
+    }
+
     @Transactional(readOnly = true)
     public Option getOptionById(Long optionId) {
         return optionRepository.findById(optionId)
@@ -119,4 +188,11 @@ public void increaseLikeCount(Long productId) {
     public void decreaseLikeCount(Long productId) {
         productRepository.decreaseLikeCount(productId);
     }
+
+    private Pageable validatedPageRequest(int page, int size) {
+        if (page < 0 || size <= 0 || size > MAX_PAGE_SIZE) {
+            throw new CoreException(ErrorType.BAD_REQUEST, "page는 0 이상, size는 1~" + MAX_PAGE_SIZE + " 범위여야 합니다.");
+        }
+        return PageRequest.of(page, size);
+    }
 }

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

@@ -0,0 +1,16 @@
+package com.loopers.application.product;
+
+import java.util.Optional;
+
+public interface ProductCacheManager {
+
+    Optional<CachedBrandProductPage> getProductList(Long brandId, int page, int size);
+
+    void putProductList(Long brandId, int page, int size, CachedBrandProductPage value);
+
+    Optional<CachedProductDetail> getProductDetail(Long productId);
+
+    void putProductDetail(Long productId, CachedProductDetail value);
+
+    void evictProductCaches(Long productId, Long brandId);
+}

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

@@ -7,6 +7,9 @@
 import com.loopers.domain.product.Product;
 import com.loopers.domain.product.ProductSortCondition;
 import lombok.RequiredArgsConstructor;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageImpl;
+import org.springframework.data.domain.PageRequest;
 import org.springframework.stereotype.Component;
 
 import java.util.List;
@@ -21,13 +24,19 @@ public class ProductFacade {
     private final LikeAppService likeAppService;
 
     public ProductInfo getProductDetail(Long productId, Long userId) {
-        Product product = productAppService.getById(productId);
-        Brand brand = brandAppService.getById(product.getBrandId());
-        List<Option> options = productAppService.getOptionsByProductId(productId);
-        long likeCount = likeAppService.countByProductId(productId);
+        CachedProductDetail detail = productAppService.getProductDetailCached(productId);
+        Brand brand = brandAppService.getById(detail.getBrandId());
         boolean likedByUser = userId != null && likeAppService.isLikedByUser(userId, productId);
+        return toProductInfo(detail, brand, likedByUser);
+    }
 
-        return ProductInfo.of(product, brand, options, likeCount, likedByUser);
+    public Page<ProductInfo> getProductsByBrand(Long brandId, int page, int size) {
+        CachedBrandProductPage cached = productAppService.getProductsByBrandIdCached(brandId, page, size);
+        Brand brand = brandAppService.getById(brandId);
+        List<ProductInfo> content = cached.getContent().stream()
+                .map(summary -> toProductInfo(summary, brand))
+                .toList();
+        return new PageImpl<>(content, PageRequest.of(page, size), cached.getTotalElements());
     }
 
     public List<ProductInfo> getProductList(ProductSortCondition condition, Long userId) {
@@ -57,4 +66,32 @@ public List<ProductInfo> getProductList(ProductSortCondition condition, Long use
                 ))
                 .toList();
     }
+
+    private ProductInfo toProductInfo(CachedProductDetail detail, Brand brand, boolean likedByUser) {
+        return ProductInfo.builder()
+                .productId(detail.getProductId())
+                .productName(detail.getProductName())
+                .basePrice(detail.getBasePrice())
+                .deleted(detail.isDeleted())
+                .brandId(brand.getId())
+                .brandName(brand.getName())
+                .likeCount(detail.getLikeCount())
+                .likedByUser(likedByUser)
+                .options(detail.getOptions())
+                .build();
+    }
+
+    private ProductInfo toProductInfo(CachedBrandProductPage.ProductSummary summary, Brand brand) {
+        return ProductInfo.builder()
+                .productId(summary.getProductId())
+                .productName(summary.getProductName())
+                .basePrice(summary.getBasePrice())
+                .deleted(summary.isDeleted())
+                .brandId(brand.getId())
+                .brandName(brand.getName())
+                .likeCount(summary.getLikeCount())
+                .likedByUser(false)
+                .options(List.of())
+                .build();
+    }
 }

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

@@ -6,11 +6,13 @@
 import com.loopers.domain.product.Product;
 import lombok.Builder;
 import lombok.Getter;
+import lombok.extern.jackson.Jacksonized;
 
 import java.util.List;
 
 @Getter
 @Builder
+@Jacksonized
 public class ProductInfo {
     private final Long productId;
     private final String productName;
@@ -24,6 +26,7 @@ public class ProductInfo {
 
     @Getter
     @Builder
+    @Jacksonized
     public static class OptionInfo {
         private final Long optionId;
         private final String optionName;
@@ -42,6 +45,20 @@ public static OptionInfo from(Option option) {
         }
     }
 
+    public ProductInfo withLikedByUser(boolean likedByUser) {
+        return ProductInfo.builder()
+                .productId(this.productId)
+                .productName(this.productName)
+                .basePrice(this.basePrice)
+                .deleted(this.deleted)
+                .brandId(this.brandId)
+                .brandName(this.brandName)
+                .likeCount(this.likeCount)
+                .likedByUser(likedByUser)
+                .options(this.options)
+                .build();
+    }
+
     public static ProductInfo of(Product product, Brand brand, List<Option> options, long likeCount, boolean likedByUser) {
         return ProductInfo.builder()
                 .productId(product.getId())

apps/commerce-api/src/main/java/com/loopers/domain/common/Money.java

@@ -1,5 +1,7 @@
 package com.loopers.domain.common;
 
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
 import com.loopers.support.error.CoreException;
 import com.loopers.support.error.ErrorType;
 import jakarta.persistence.Embeddable;
@@ -17,7 +19,8 @@
 public class Money {
     private BigDecimal amount;
 
-    private Money(BigDecimal amount) {
+    @JsonCreator
+    private Money(@JsonProperty("amount") BigDecimal amount) {
         if (amount == null || amount.compareTo(BigDecimal.ZERO) < 0) {
             throw new CoreException(ErrorType.BAD_REQUEST, "금액은 0 이상이어야 합니다.");
         }
@@ -55,7 +58,7 @@ public boolean isGreaterThanOrEqual(Money other) {
     public Money subtract(Money other) {
         BigDecimal result = this.amount.subtract(other.amount);
         if (result.compareTo(BigDecimal.ZERO) < 0) {
-            throw new IllegalArgumentException(
+            throw new CoreException(ErrorType.BAD_REQUEST,
                     "차감 결과가 음수입니다: " + this.amount + " - " + other.amount + " = " + result);
         }
         return new Money(result);