Lock으로 사용자 기준 특정 기능 동시 실행 막기

src/main/java/com/ayucoupon/common/handler/CouponExceptionHandler.java

@@ -7,6 +7,8 @@
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
 
+import java.util.ConcurrentModificationException;
+
 @RestControllerAdvice(basePackages = "com.ayucoupon")
 public class CouponExceptionHandler {
 
@@ -27,7 +29,13 @@ public ResponseEntity<String> handle(IllegalStateException e) {
         return ResponseEntity.status(HttpStatus.BAD_REQUEST)
                 .body(e.getMessage());
     }
-
+
+    @ExceptionHandler(ConcurrentModificationException.class)
+    public ResponseEntity<String> handle(ConcurrentModificationException e) {
+        return ResponseEntity.status(HttpStatus.BAD_REQUEST)
+                .body(e.getMessage());
+    }
+
     @ExceptionHandler(BaseCustomException.class)
     public ResponseEntity<String> handle(BaseCustomException e) {
         return ResponseEntity.status(e.getStatus())

src/main/java/com/ayucoupon/common/lock/RunnerLock.java

@@ -0,0 +1,37 @@
+package com.ayucoupon.common.lock;
+
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+public class RunnerLock {
+
+    private final Lock lock;
+    private int count;
+
+    public RunnerLock() {
+        this.lock = new ReentrantLock(true);
+        this.count = 0;
+    }
+
+    public boolean tryLock() {
+        return lock.tryLock();
+    }
+
+    public boolean tryLock(Long time, TimeUnit unit) throws InterruptedException {
+        return lock.tryLock(time, unit);
+    }
+
+    public void unLock() {
+        lock.unlock();
+    }
+
+    public int increase() {
+        return ++count;
+    }
+
+    public int decrease() {
+        return --count;
+    }
+
+}

src/main/java/com/ayucoupon/common/lock/UserExclusiveRunner.java

@@ -0,0 +1,47 @@
+package com.ayucoupon.common.lock;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+import org.springframework.util.Assert;
+
+import java.time.Duration;
+import java.util.ConcurrentModificationException;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Supplier;
+
+@Component
+@Slf4j
+public class UserExclusiveRunner {
+
+    private final ConcurrentMap<Long, RunnerLock> map = new ConcurrentHashMap<>();
+
+    public <T> T call(Long userId, Duration tryLockTimeout, Supplier<T> f) {
+        Assert.notNull(tryLockTimeout, "tryLockTimeout must not be null");
+
+        RunnerLock lock = map.computeIfAbsent(userId, k -> new RunnerLock());
+        lock.increase();
+        try {
+            log.debug("Method \"{}\" tried to get lock of \"{}\"", f.getClass().getSimpleName(), this.getClass().getSimpleName());
+            if (lock.tryLock(tryLockTimeout.toMillis(), TimeUnit.MILLISECONDS)) {
+                log.debug("User {} get lock of \"{}\"", userId, this.getClass().getSimpleName());
+                try {
+                    return f.get();
+                } finally {
+                    int count = lock.decrease();
+                    if (count <= 0) {
+                        map.remove(userId, lock);
+                    }
+                    log.debug("User {} release lock of \"{}\"", userId, this.getClass().getSimpleName());
+                    lock.unLock();
+                }
+            }
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        log.debug("User {} fail to get Lock of \"{}\"", userId, this.getClass().getSimpleName());
+        throw new ConcurrentModificationException("동시에 같은 요청을 보낼 수 없습니다.");
+    }
+
+}

src/main/java/com/ayucoupon/usercoupon/service/issue/IssueUserCouponService.java

@@ -1,20 +1,26 @@
 package com.ayucoupon.usercoupon.service.issue;
 
+import com.ayucoupon.common.lock.UserExclusiveRunner;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
-import org.springframework.transaction.annotation.Transactional;
+
+import java.time.Duration;
 
 @Service
 @RequiredArgsConstructor
-@Transactional
 public class IssueUserCouponService {
 
     private final IssueUserCouponModule issueUserCouponModule;
     private final IssueValidator issueValidator;
+    private final UserExclusiveRunner userExclusiveRunner;
 
     public Long issue(IssueUserCouponCommand command) {
-        issueValidator.validate(command);
-        return issueUserCouponModule.issue(command);
+        return userExclusiveRunner.call(command.userId(),
+                Duration.ofSeconds(30),
+                () -> {
+                    issueValidator.validate(command);
+                    return issueUserCouponModule.issue(command);
+                });
     }
 
 }

src/test/java/com/ayucoupon/usercoupon/service/IssueCouponServiceTest.java

@@ -73,6 +73,39 @@ public void issueCouponForInvalidCoupon() {
                 .hasMessage("발급 요청된 쿠폰이 존재하지 않습니다.");
     }
 
+    @DisplayName("동일한 사용자가 동시에 쿠폰 발급 요청을 보낼 수 없다.")
+    @Test
+    public void multiIssueCouponOfSameUser() throws InterruptedException {
+        //given
+        Long couponId = 1L;
+        Long userId = 1L;
+        long issueCount = 5L;
+        AtomicInteger duplicatedCouponExceptionCount = new AtomicInteger();
+
+        int couponLeftQuantity = (int) issueCount;
+        int numberOfThreads = (int) issueCount;
+
+        ExecutorService service = Executors.newFixedThreadPool(numberOfThreads);
+        CountDownLatch latch = new CountDownLatch(couponLeftQuantity);
+
+        //when
+        IssueUserCouponCommand command = new IssueUserCouponCommand(userId, couponId);
+        for (int i = 1; i <= issueCount; i++) {
+            CompletableFuture
+                    .runAsync(() -> issueCouponService.issue(command), service)
+                    .whenComplete((result, error) -> {
+                        if (error != null && error.getCause() instanceof DuplicatedCouponException)
+                            duplicatedCouponExceptionCount.incrementAndGet();
+                        latch.countDown();
+                    });
+        }
+        latch.await();
+
+        // then
+        assertThat(duplicatedCouponExceptionCount.get()).isEqualTo(issueCount - 1);
+    }
+
+
     @DisplayName("쿠폰을 발급하면, 쿠폰 재고가 감소한다.")
     @Test
     public void pessimisticLockIssueCouponTest() throws InterruptedException {