From ab0a48f770f914006651f7023dcf411b70e39f05 Mon Sep 17 00:00:00 2001
From: haerong22 <haerong22@naver.com>
Date: Wed, 21 Dec 2022 00:50:51 +0900
Subject: [PATCH] #27 stock: race condition solution 3 - redis(redisson)

---
 stock/build.gradle                            |  3 +
 .../stock/facade/RedissonLockStockFacade.java | 37 +++++++++++
 .../facade/RedissonLockStockFacadeTest.java   | 61 +++++++++++++++++++
 3 files changed, 101 insertions(+)
 create mode 100644 stock/src/main/java/com/example/stock/facade/RedissonLockStockFacade.java
 create mode 100644 stock/src/test/java/com/example/stock/facade/RedissonLockStockFacadeTest.java

diff --git a/stock/build.gradle b/stock/build.gradle
index 7af3be33..f7f0d897 100644
--- a/stock/build.gradle
+++ b/stock/build.gradle
@@ -22,6 +22,9 @@ dependencies {
     implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
     implementation 'org.springframework.boot:spring-boot-starter-data-redis'
     implementation 'org.springframework.boot:spring-boot-starter-web'
+
+    implementation 'org.redisson:redisson-spring-boot-starter:3.19.0'
+
     compileOnly 'org.projectlombok:lombok'
     runtimeOnly 'com.mysql:mysql-connector-j'
     annotationProcessor 'org.projectlombok:lombok'
diff --git a/stock/src/main/java/com/example/stock/facade/RedissonLockStockFacade.java b/stock/src/main/java/com/example/stock/facade/RedissonLockStockFacade.java
new file mode 100644
index 00000000..168aef20
--- /dev/null
+++ b/stock/src/main/java/com/example/stock/facade/RedissonLockStockFacade.java
@@ -0,0 +1,37 @@
+package com.example.stock.facade;
+
+import com.example.stock.service.StockService;
+import lombok.RequiredArgsConstructor;
+import org.redisson.api.RLock;
+import org.redisson.api.RedissonClient;
+import org.springframework.stereotype.Component;
+
+import java.util.concurrent.TimeUnit;
+
+@Component
+@RequiredArgsConstructor
+public class RedissonLockStockFacade {
+
+    private final RedissonClient redissonClient;
+
+    private final StockService stockService;
+
+    public void decrease(Long id, Long quantity) {
+        RLock lock = redissonClient.getLock(id.toString());
+
+        try {
+            boolean available = lock.tryLock(10, 1, TimeUnit.SECONDS);
+
+            if (!available) {
+                System.out.println("get lock fail.");
+                return;
+            }
+
+            stockService.decrease(id, quantity);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        } finally {
+            lock.unlock();
+        }
+    }
+}
diff --git a/stock/src/test/java/com/example/stock/facade/RedissonLockStockFacadeTest.java b/stock/src/test/java/com/example/stock/facade/RedissonLockStockFacadeTest.java
new file mode 100644
index 00000000..25bc8d53
--- /dev/null
+++ b/stock/src/test/java/com/example/stock/facade/RedissonLockStockFacadeTest.java
@@ -0,0 +1,61 @@
+package com.example.stock.facade;
+
+import com.example.stock.domain.Stock;
+import com.example.stock.repository.StockRepository;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@SpringBootTest
+class RedissonLockStockFacadeTest {
+    @Autowired
+    private RedissonLockStockFacade redissonLockStockFacade;
+
+    @Autowired
+    private StockRepository stockRepository;
+
+    @BeforeEach
+    public void before() {
+        Stock stock = new Stock(1L, 100L);
+
+        stockRepository.saveAndFlush(stock);
+    }
+
+    @AfterEach
+    public void after() {
+        stockRepository.deleteAll();
+    }
+
+    @Test
+    public void 동시에_100개의_요청_redisson() throws InterruptedException {
+        int threadCount = 100;
+        ExecutorService executorService = Executors.newFixedThreadPool(32);
+
+        CountDownLatch latch = new CountDownLatch(threadCount);
+
+        for (int i = 0; i < threadCount; i++) {
+            executorService.submit(() -> {
+                try {
+                    redissonLockStockFacade.decrease(1L, 1L);
+                } finally {
+                    latch.countDown();
+                }
+            });
+        }
+
+        latch.await();
+
+        Stock stock = stockRepository.findById(1L).orElseThrow();
+
+        // 100 - (1 * 100) = 0
+        assertEquals(0L, stock.getQuantity());
+    }
+}
\ No newline at end of file