♻️ 쿠폰 발행 - lua script를 활용한 atomic연산 방식으로 변경

src/main/java/kr/bb/store/domain/coupon/handler/CouponIssuer.java

@@ -9,39 +9,43 @@
 import kr.bb.store.domain.coupon.exception.ExpiredCouponException;
 import kr.bb.store.domain.coupon.repository.IssuedCouponRepository;
 import kr.bb.store.util.RedisOperation;
-import lombok.RequiredArgsConstructor;
+import kr.bb.store.util.luascript.CouponLockExecutor;
+import kr.bb.store.util.luascript.RedisLuaScriptExecutor;
 import org.springframework.stereotype.Component;
 
 import java.time.LocalDate;
 import java.util.List;
 import java.util.function.Predicate;
 
 import static kr.bb.store.util.RedisUtils.makeRedisKey;
+import static kr.bb.store.util.luascript.LockScript.script;
 
-@RequiredArgsConstructor
 @Component
 public class CouponIssuer {
     private final IssuedCouponRepository issuedCouponRepository;
+    private final RedisLuaScriptExecutor redisLuaScriptExecutor;
     private final RedisOperation redisOperation;
 
+    public CouponIssuer(IssuedCouponRepository issuedCouponRepository, CouponLockExecutor couponLockExecutor, RedisOperation redisOperation) {
+        this.issuedCouponRepository = issuedCouponRepository;
+        this.redisLuaScriptExecutor = couponLockExecutor;
+        this.redisOperation = redisOperation;
+    }
+
     public IssuedCoupon issueCoupon(Coupon coupon, Long userId, String nickname, String phoneNumber, LocalDate issueDate) {
         if(coupon.getIsDeleted()) throw new DeletedCouponException();
         if(coupon.isExpired(issueDate)) throw new ExpiredCouponException();
 
         String redisKey = makeRedisKey(coupon);
         String redisValue = userId.toString();
+        Integer limitCnt = coupon.getLimitCount();
         if(isDuplicated(redisKey, redisValue)) throw new AlreadyIssuedCouponException();
 
-        List<Long> result = (List) redisOperation.countAndSet(redisKey, redisValue);
-
-        Integer limitCnt = coupon.getLimitCount();
-        Long issueCount = result.get(0);
-        if(isExhausted(limitCnt,issueCount)) {
-            redisOperation.remove(redisKey, redisValue);
-            throw new CouponOutOfStockException();
+        boolean issuable = (Boolean)redisLuaScriptExecutor.execute(script, redisKey, redisValue, limitCnt);
+        if(issuable) {
+            return issuedCouponRepository.save(makeIssuedCoupon(coupon,userId,nickname,phoneNumber));
         }
-
-        return issuedCouponRepository.save(makeIssuedCoupon(coupon,userId,nickname,phoneNumber));
+        throw new CouponOutOfStockException();
     }
 
     public void issuePossibleCoupons(List<Coupon> coupons, Long userId, String nickname, String phoneNumber, LocalDate issueDate) {
@@ -56,16 +60,9 @@ public void issuePossibleCoupons(List<Coupon> coupons, Long userId, String nickn
                 }))
                 .filter(coupon -> {
                     String redisKey = makeRedisKey(coupon);
-
-                    List<Long> result = (List) redisOperation.countAndSet(redisKey, redisValue);
-
                     Integer limitCnt = coupon.getLimitCount();
-                    Long issueCount = result.get(0);
-                    if(isExhausted(limitCnt,issueCount)) {
-                        redisOperation.remove(redisKey, redisValue);
-                        return false;
-                    }
-                    return true;
+                    boolean issuable = (Boolean)redisLuaScriptExecutor.execute(script, redisKey, redisValue, limitCnt);
+                    return issuable;
                 })
                 .forEach(coupon -> issuedCouponRepository.save(makeIssuedCoupon(coupon,userId,nickname,phoneNumber)));
     }
@@ -86,15 +83,6 @@ private IssuedCouponId makeIssuedCouponId(Long couponId, Long userId) {
                 .build();
     }
 
-    /*
-     * 모든 쿠폰은 생성시 expirationDate 설정을 위해 DUMMY_DATA를 넣어 redis에 등록됩니다.
-     * 하나의 데이터가 더 들어있기 때문에 이를 고려해 '<=' 가 아닌 '<'로 개수를 비교해야
-     * 쿠폰에 등록한 limitCount만큼 발급이 가능합니다.
-     */
-    private boolean isExhausted(Integer limitCount, Long issueCount) {
-        return limitCount < issueCount;
-    }
-
     private boolean isDuplicated(String redisKey, String value) {
         return redisOperation.contains(redisKey, value);
     }

src/main/java/kr/bb/store/util/luascript/CouponLockExecutor.java

@@ -0,0 +1,23 @@
+package kr.bb.store.util.luascript;
+
+import lombok.RequiredArgsConstructor;
+import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.data.redis.core.script.DefaultRedisScript;
+import org.springframework.data.redis.core.script.RedisScript;
+import org.springframework.stereotype.Component;
+
+import java.util.Collections;
+
+@Component
+@RequiredArgsConstructor
+public class CouponLockExecutor implements RedisLuaScriptExecutor{
+
+    private final RedisTemplate<String,String> redisTemplate;
+
+    @Override
+    public Boolean execute(String script, String key, Object... args) {
+        RedisScript<Boolean> redisScript = new DefaultRedisScript<>(script, Boolean.class);
+        return redisTemplate.execute(redisScript, Collections.singletonList(key), args[0], String.valueOf(args[1]));
+    }
+
+}

src/main/java/kr/bb/store/util/luascript/LockScript.java

@@ -0,0 +1,19 @@
+package kr.bb.store.util.luascript;
+
+public class LockScript {
+    /*
+     * 모든 쿠폰은 expirationDate 설정을 위해 생성 시점에 DUMMY_DATA를 넣어 redis에 등록됩니다.
+     * 결과적으로 하나의 데이터(DUMMY_DATA)가 더 들어있기 때문에 이를 고려해 '<='가 아닌 '<'로 개수를 비교해야
+     * 쿠폰을 생성할 때 설정한 limitCnt수 만큼 발급받게 할 수 있습니다.
+     */
+    public static final String script = "local key = KEYS[1]\n" +
+            "local value = ARGV[1]\n" +
+            "local limitCnt = tonumber(ARGV[2])\n" +
+            "local currentCnt = redis.call('SCARD', key)\n" +
+            "if currentCnt <= limitCnt then\n" +
+            "    redis.call('SADD', key, value)\n" +
+            "    return true\n" +
+            "else\n" +
+            "    return false\n" +
+            "end";
+}

src/main/java/kr/bb/store/util/luascript/RedisLuaScriptExecutor.java

@@ -0,0 +1,5 @@
+package kr.bb.store.util.luascript;
+
+public interface RedisLuaScriptExecutor {
+    Object execute(String script, String key, Object... args);
+}