[PR] 재고 관련 동시성 처리

build.gradle

@@ -22,7 +22,10 @@ dependencies {
     implementation 'org.springframework.boot:spring-boot-starter-web'
 
     implementation 'org.springframework.session:spring-session-data-redis'
+    compileOnly 'org.projectlombok:lombok'
+    annotationProcessor 'org.projectlombok:lombok'
     runtimeOnly 'com.mysql:mysql-connector-j'
+    implementation 'org.redisson:redisson-spring-boot-starter:3.50.0'
 
     testImplementation 'org.springframework.boot:spring-boot-starter-test'
     testRuntimeOnly 'org.junit.platform:junit-platform-launcher'

src/main/java/com/example/locktest/adapter/in/web/ItemController.java

@@ -0,0 +1,61 @@
+package com.example.locktest.adapter.in.web;
+
+import com.example.locktest.application.command.CreateItemCommand;
+import com.example.locktest.application.command.DecreaseItemCommand;
+import com.example.locktest.application.command.UpdateItemCommand;
+import com.example.locktest.application.port.in.CreateItemUseCase;
+import com.example.locktest.application.port.in.DecreaseItemUseCase;
+import com.example.locktest.application.port.in.UpdateItemUseCase;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/v1/api/items")
+public class ItemController {
+
+    private final CreateItemUseCase createItemUseCase;
+    private final UpdateItemUseCase updateItemUseCase;
+    private final DecreaseItemUseCase syncDecreaseItemUseCase;
+    private final DecreaseItemUseCase redisDecreaseItemUseCase;
+    private final DecreaseItemUseCase optimisticDecreaseItemUseCase;
+
+    public ItemController(CreateItemUseCase createItemUseCase,
+                          UpdateItemUseCase updateItemUseCase,
+                          @Qualifier("javaSyncDecreaseItemUseCase") DecreaseItemUseCase sync,
+                          @Qualifier("dbDecreaseItemUseCase") DecreaseItemUseCase optimistic,
+                          @Qualifier("redisDecreaseItemUseCase") DecreaseItemUseCase redis) {
+        this.createItemUseCase = createItemUseCase;
+        this.updateItemUseCase = updateItemUseCase;
+        this.syncDecreaseItemUseCase = sync;
+        this.optimisticDecreaseItemUseCase = optimistic;
+        this.redisDecreaseItemUseCase = redis;
+    }
+
+    @PostMapping
+    public ResponseEntity<Long> createItem(@RequestBody CreateItemCommand command) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(createItemUseCase.createItem(command));
+    }
+
+    @PutMapping
+    public ResponseEntity<Long> updateItem(@RequestBody UpdateItemCommand command) {
+        return ResponseEntity.ok().body(updateItemUseCase.updateItem(command));
+    }
+
+    @PostMapping("/decrease/sync")
+    public ResponseEntity<Long> decreaseItemWithSync(@RequestBody DecreaseItemCommand command) {
+        return ResponseEntity.ok(syncDecreaseItemUseCase.decreaseItem(command));
+    }
+
+    @PostMapping("/decrease/optimistic")
+    public ResponseEntity<Long> decreaseItemWithOptimistic(@RequestBody DecreaseItemCommand command) {
+        return ResponseEntity.ok(optimisticDecreaseItemUseCase.decreaseItem(command));
+    }
+
+    @PostMapping("/decrease/redis")
+    public ResponseEntity<Long> decreaseItemWithRedis(@RequestBody DecreaseItemCommand command) {
+        return ResponseEntity.ok(redisDecreaseItemUseCase.decreaseItem(command));
+    }
+
+}

src/main/java/com/example/locktest/adapter/out/lock/DecreaseWithOptimisticLockAdapter.java

@@ -0,0 +1,12 @@
+package com.example.locktest.adapter.out.lock;
+
+import com.example.locktest.application.port.out.ItemLockPort;
+
+public class DecreaseWithOptimisticLockAdapter implements ItemLockPort {
+
+    @Override
+    public void lock(Long itemId) { }
+
+    @Override
+    public void unlock(Long itemId) { }
+}

src/main/java/com/example/locktest/adapter/out/lock/DecreaseWithRedisLockAdapter.java

@@ -0,0 +1,38 @@
+package com.example.locktest.adapter.out.lock;
+
+import com.example.locktest.application.port.out.ItemLockPort;
+import org.redisson.api.RLock;
+import org.redisson.api.RedissonClient;
+
+import java.util.concurrent.TimeUnit;
+
+public class DecreaseWithRedisLockAdapter implements ItemLockPort {
+
+    private final RedissonClient redissonClient;
+
+    public DecreaseWithRedisLockAdapter(RedissonClient redissonClient) {
+        this.redissonClient = redissonClient;
+    }
+
+    @Override
+    public void lock(Long itemId) {
+        RLock lock = redissonClient.getLock("item_lock_" + itemId);
+        try {
+            System.out.println(Thread.currentThread().getName() + " - try to lock: " + itemId);
+            lock.lock(5, TimeUnit.SECONDS);
+            System.out.println(Thread.currentThread().getName() + " - lock acquired: " + itemId);
+        } catch (Exception e) {
+            throw new IllegalStateException("lock fail", e);
+        }
+    }
+
+    @Override
+    public void unlock(Long itemId) {
+        RLock lock = redissonClient.getLock("item_lock_" + itemId);
+        if (lock.isHeldByCurrentThread()) {
+            lock.unlock();
+            System.out.println(Thread.currentThread().getName() + " - unlock: " + itemId);
+        }
+    }
+
+}

src/main/java/com/example/locktest/adapter/out/lock/DecreaseWithSynchronizedLockAdapter.java

@@ -0,0 +1,26 @@
+package com.example.locktest.adapter.out.lock;
+
+import com.example.locktest.application.port.out.ItemLockPort;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class DecreaseWithSynchronizedLockAdapter implements ItemLockPort {
+
+    // 아이템별로 락 오브젝트를 관리하는 맵
+    private final Map<Long, Object> locks = new ConcurrentHashMap<>();
+
+    @Override
+    public void lock(Long itemId) {
+        Object lock = locks.computeIfAbsent(itemId, k -> new Object());
+        synchronized (lock) {
+            // synchronized로 락 획득 → 이후 작업은 UseCase에서 수행됨
+        }
+    }
+
+    @Override
+    public void unlock(Long itemId) {
+        // synchronized는 자동 해제되므로 별도 unlock 필요 없음
+        // 하지만 인터페이스 맞추기 위해 dummy 구현 제공
+    }
+}

src/main/java/com/example/locktest/adapter/out/persistence/JpaItemRepository.java

@@ -0,0 +1,48 @@
+package com.example.locktest.adapter.out.persistence;
+
+import com.example.locktest.adapter.out.persistence.entity.ItemEntity;
+import com.example.locktest.application.port.out.ItemRepository;
+import com.example.locktest.domain.model.Item;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.time.LocalDateTime;
+import java.util.Optional;
+
+public class JpaItemRepository implements ItemRepository {
+
+    private final SpringDataItemRepository springDataItemRepository;
+
+    public JpaItemRepository(SpringDataItemRepository springDataItemRepository) {
+        this.springDataItemRepository = springDataItemRepository;
+    }
+
+    @Transactional
+    @Override
+    public Long save(Item item) {
+        ItemEntity entity = ItemEntity.builder()
+                .name(item.getName())
+                .amount(item.getAmount())
+                .creatAt(LocalDateTime.now())
+                .build();
+        ItemEntity saved = springDataItemRepository.save(entity);
+        return saved.getId();
+    }
+
+    @Transactional
+    @Override
+    public Long update(Item newItem) {
+        ItemEntity entity = springDataItemRepository.findById(newItem.getId()).orElseThrow(
+                () -> new RuntimeException("Item not found")
+        );
+        entity.update(newItem);
+        return entity.getId();
+    }
+
+    @Transactional(readOnly = true)
+    @Override
+    public Optional<Item> findById(Long id) {
+        return springDataItemRepository.findById(id)
+                .map(ItemEntity::toDomain);
+
+    }
+}

src/main/java/com/example/locktest/adapter/out/persistence/SpringDataItemRepository.java

@@ -0,0 +1,7 @@
+package com.example.locktest.adapter.out.persistence;
+
+import com.example.locktest.adapter.out.persistence.entity.ItemEntity;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface SpringDataItemRepository extends JpaRepository<ItemEntity, Long> {
+}

src/main/java/com/example/locktest/adapter/out/persistence/entity/ItemEntity.java

@@ -0,0 +1,48 @@
+package com.example.locktest.adapter.out.persistence.entity;
+
+import com.example.locktest.domain.model.Item;
+import jakarta.persistence.*;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.time.LocalDateTime;
+
+@Getter
+@Table(name = "items")
+@NoArgsConstructor
+@Entity
+public class ItemEntity {
+
+    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(nullable = false)
+    private String name;
+
+    @Column(nullable = false)
+    private Long amount;
+
+    @Version
+    private Long version; // OptimisticLock 을 위해 사용
+
+    @Column(nullable = false)
+    private LocalDateTime creatAt;
+
+    @Builder
+    public ItemEntity(String name, Long amount, LocalDateTime creatAt) {
+        this.name = name;
+        this.amount = amount;
+        this.creatAt = creatAt;
+    }
+
+    public void update(Item item) {
+        this.name = item.getName();
+        this.amount = item.getAmount();
+    }
+
+    public Item toDomain() {
+        return new Item(id, name, amount, creatAt);
+    }
+}
+

src/main/java/com/example/locktest/application/command/CreateItemCommand.java

@@ -0,0 +1,3 @@
+package com.example.locktest.application.command;
+
+public record CreateItemCommand(String name, Long amount) {}

src/main/java/com/example/locktest/application/command/DecreaseItemCommand.java

@@ -0,0 +1,4 @@
+package com.example.locktest.application.command;
+
+public record DecreaseItemCommand(Long id, Long quantity) {
+}

src/main/java/com/example/locktest/application/command/UpdateItemCommand.java

@@ -0,0 +1,4 @@
+package com.example.locktest.application.command;
+
+public record UpdateItemCommand(Long id, String name, Long amount) {
+}

src/main/java/com/example/locktest/application/port/in/CreateItemUseCase.java

@@ -0,0 +1,7 @@
+package com.example.locktest.application.port.in;
+
+import com.example.locktest.application.command.CreateItemCommand;
+
+public interface CreateItemUseCase {
+    Long createItem(CreateItemCommand command);
+}

src/main/java/com/example/locktest/application/port/in/DecreaseItemUseCase.java

@@ -0,0 +1,7 @@
+package com.example.locktest.application.port.in;
+
+import com.example.locktest.application.command.DecreaseItemCommand;
+
+public interface DecreaseItemUseCase {
+    Long decreaseItem(DecreaseItemCommand command);
+}

src/main/java/com/example/locktest/application/port/in/UpdateItemUseCase.java

@@ -0,0 +1,7 @@
+package com.example.locktest.application.port.in;
+
+import com.example.locktest.application.command.UpdateItemCommand;
+
+public interface UpdateItemUseCase {
+    Long updateItem(UpdateItemCommand command);
+}

src/main/java/com/example/locktest/application/port/out/ItemLockPort.java

@@ -0,0 +1,6 @@
+package com.example.locktest.application.port.out;
+
+public interface ItemLockPort {
+    void lock(Long itemId);
+    void unlock(Long itemId);
+}

src/main/java/com/example/locktest/application/port/out/ItemRepository.java

@@ -0,0 +1,11 @@
+package com.example.locktest.application.port.out;
+
+import com.example.locktest.domain.model.Item;
+
+import java.util.Optional;
+
+public interface ItemRepository {
+    Long save(Item item);
+    Long update(Item newItem);
+    Optional<Item> findById(Long id);
+}

src/main/java/com/example/locktest/application/service/CreateItemService.java

@@ -0,0 +1,24 @@
+package com.example.locktest.application.service;
+
+import com.example.locktest.application.command.CreateItemCommand;
+import com.example.locktest.application.port.in.CreateItemUseCase;
+import com.example.locktest.application.port.out.ItemRepository;
+import com.example.locktest.domain.model.Item;
+
+import java.time.LocalDateTime;
+
+public class CreateItemService implements CreateItemUseCase {
+
+    private final ItemRepository itemRepository;
+
+    public CreateItemService(ItemRepository itemRepository) {
+        this.itemRepository = itemRepository;
+    }
+
+    @Override
+    public Long createItem(CreateItemCommand command) {
+        Item item = new Item(null, command.name(), command.amount(), LocalDateTime.now());
+        item.validate();
+        return itemRepository.save(item);
+    }
+}

src/main/java/com/example/locktest/application/service/DecreaseItemService.java

@@ -0,0 +1,31 @@
+package com.example.locktest.application.service;
+
+import com.example.locktest.application.command.DecreaseItemCommand;
+import com.example.locktest.application.port.in.DecreaseItemUseCase;
+import com.example.locktest.application.port.out.ItemLockPort;
+import com.example.locktest.application.port.out.ItemRepository;
+import com.example.locktest.domain.model.Item;
+
+public class DecreaseItemService implements DecreaseItemUseCase {
+
+    private final ItemRepository itemRepository;
+    private final ItemLockPort itemLockPort;
+
+    public DecreaseItemService(ItemRepository itemRepository, ItemLockPort itemLockPort) {
+        this.itemRepository = itemRepository;
+        this.itemLockPort = itemLockPort;
+    }
+
+    @Override
+    public Long decreaseItem(DecreaseItemCommand command) {
+        itemLockPort.lock(command.id());
+        try {
+            Item item = itemRepository.findById(command.id())
+                    .orElseThrow(() -> new RuntimeException("해당 상품을 찾을 수 없습니다."));
+            Item updateItem = item.decrease(command.quantity());
+            return itemRepository.update(updateItem);
+        } finally {
+            itemLockPort.unlock(command.id());
+        }
+    }
+}

src/main/java/com/example/locktest/application/service/UpdateItemService.java

@@ -0,0 +1,23 @@
+package com.example.locktest.application.service;
+
+import com.example.locktest.application.command.UpdateItemCommand;
+import com.example.locktest.application.port.in.UpdateItemUseCase;
+import com.example.locktest.application.port.out.ItemRepository;
+import com.example.locktest.domain.model.Item;
+
+public class UpdateItemService implements UpdateItemUseCase {
+
+    private final ItemRepository itemRepository;
+
+    public UpdateItemService(ItemRepository itemRepository) {
+        this.itemRepository = itemRepository;
+    }
+
+    @Override
+    public Long updateItem(UpdateItemCommand command) {
+        Item item = itemRepository.findById(command.id())
+                .orElseThrow(() -> new RuntimeException("Item not found"));
+        item.update(command.name(), command.amount());
+        return itemRepository.update(item);
+    }
+}