Redis 缓存库存信息，减少 DB 压力

daydreamdev · Jun 8, 2019 · fca2e1e · fca2e1e
1 parent 7db7bd1
commit fca2e1e
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Showing 9 changed files with 295 additions and 118 deletions.
diff --git a/.idea/workspace.xml b/.idea/workspace.xml
diff --git a/HELP.md b/HELP.md
diff --git a/src/main/java/com/daydreamdev/secondskill/common/Limit/RedisLimit.java b/src/main/java/com/daydreamdev/secondskill/common/Limit/RedisLimit.java
@@ -38,10 +38,10 @@ public static Boolean limit() {
                 return true;
             }
         } catch (Exception e) {
-            log.error("获取 Jedis 实例失败：", e);
-            RedisPool.returnBrokenResource(jedis);
+            log.error("Limit 获取 Jedis 实例失败：", e);
+        } finally {
+            RedisPool.jedisPoolClose(jedis);
         }
-        RedisPool.returnResource(jedis);
         return false;
     }
 }
diff --git a/src/main/java/com/daydreamdev/secondskill/common/RedisKeysConstant.java b/src/main/java/com/daydreamdev/secondskill/common/RedisKeysConstant.java
@@ -10,4 +10,19 @@ public class RedisKeysConstant {
      * 库存
      */
     public final static String STOCK = "stock_";
+
+    /**
+     * 库存值
+     */
+    public final static String STOCK_COUNT = "stock_count_";
+
+    /**
+     * 库存值
+     */
+    public final static String STOCK_SALE = "stock_sale_";
+
+    /**
+     * 库存值
+     */
+    public final static String STOCK_VERSION = "stock_version_";
 }
diff --git a/src/main/java/com/daydreamdev/secondskill/common/RedisPreheatRunner.java b/src/main/java/com/daydreamdev/secondskill/common/RedisPreheatRunner.java
@@ -23,10 +23,21 @@ public class RedisPreheatRunner implements ApplicationRunner {
     public void run(ApplicationArguments args) throws Exception {
         // 从数据库中查询热卖商品
         Stock stock = stockService.getStockById(1);
+
         // 删除 Redis 中旧的缓存
         RedisPoolUtil.del(RedisKeysConstant.STOCK + stock.getId());
         // 缓存预热
         RedisPoolUtil.listPut(RedisKeysConstant.STOCK + stock.getId(), String.valueOf(stock.getCount()),
                 String.valueOf(stock.getSale()), String.valueOf(stock.getVersion()));
+
+        // 删除旧缓存
+        RedisPoolUtil.del(RedisKeysConstant.STOCK_COUNT + stock.getCount());
+        RedisPoolUtil.del(RedisKeysConstant.STOCK_SALE + stock.getSale());
+        RedisPoolUtil.del(RedisKeysConstant.STOCK_VERSION + stock.getVersion());
+        //缓存预热
+        int sid = stock.getId();
+        RedisPoolUtil.set(RedisKeysConstant.STOCK_COUNT + sid, String.valueOf(stock.getCount()));
+        RedisPoolUtil.set(RedisKeysConstant.STOCK_SALE + sid, String.valueOf(stock.getSale()));
+        RedisPoolUtil.set(RedisKeysConstant.STOCK_VERSION + sid, String.valueOf(stock.getVersion()));
     }
 }
diff --git a/src/main/java/com/daydreamdev/secondskill/common/StockWithRedis/UpdateStockWithRedis.java b/src/main/java/com/daydreamdev/secondskill/common/StockWithRedis/UpdateStockWithRedis.java
@@ -0,0 +1,42 @@
+package com.daydreamdev.secondskill.common.StockWithRedis;
+
+import com.daydreamdev.secondskill.common.RedisKeysConstant;
+import com.daydreamdev.secondskill.common.utils.RedisPool;
+import com.daydreamdev.secondskill.common.utils.RedisPoolUtil;
+import com.daydreamdev.secondskill.pojo.Stock;
+import lombok.extern.slf4j.Slf4j;
+import redis.clients.jedis.Jedis;
+import redis.clients.jedis.Transaction;
+
+import java.util.List;
+
+/**
+ * @auther G.Fukang
+ * @date 6/8 21:47
+ */
+@Slf4j
+public class UpdateStockWithRedis {
+
+    /**
+     * Redis 事务保证库存更新
+     * 捕获异常后应该删除缓存
+     */
+    public static void updateStockWithRedis(Stock stock) {
+        Jedis jedis = null;
+        try {
+            jedis = RedisPool.getJedis();
+            // 开始事务
+            Transaction transaction = jedis.multi();
+            // 事务操作
+            RedisPoolUtil.decr(RedisKeysConstant.STOCK_COUNT + stock.getId());
+            RedisPoolUtil.incr(RedisKeysConstant.STOCK_SALE + stock.getId());
+            RedisPoolUtil.incr(RedisKeysConstant.STOCK_VERSION + stock.getId());
+            // 结束事务
+            List<Object> list = transaction.exec();
+        } catch (Exception e) {
+            log.error("updateStock 获取 Jedis 实例失败：", e);
+        } finally {
+            RedisPool.jedisPoolClose(jedis);
+        }
+    }
+}
diff --git a/src/main/java/com/daydreamdev/secondskill/common/utils/RedisPoolUtil.java b/src/main/java/com/daydreamdev/secondskill/common/utils/RedisPoolUtil.java
@@ -13,24 +13,6 @@
 @Slf4j
 public class RedisPoolUtil {
 
-    /**
-     * 判断 key - value 是否存在
-     */
-    public static Boolean exists(String key) {
-        Jedis jedis = null;
-        Boolean result = false;
-
-        try {
-            jedis = RedisPool.getJedis();
-            result = jedis.exists(key);
-        } catch (Exception e) {
-            log.error("exists key:{} value:{} error", key, e);
-        } finally {
-            RedisPool.jedisPoolClose(jedis);
-        }
-        return result;
-    }
-
     /**
      * 设置 key - value 值
      *
@@ -91,6 +73,40 @@ public static Long del(String key) {
         return result;
     }
 
+    /**
+     * key - value 自增
+     */
+    public static Long incr (String key) {
+        Jedis jedis = null;
+        Long result = null;
+        try {
+            jedis = RedisPool.getJedis();
+            result = jedis.incr(key);
+        } catch (Exception e) {
+            log.error("listGet key:{} error", key, e);
+        } finally {
+            RedisPool.jedisPoolClose(jedis);
+        }
+        return result;
+    }
+
+    /**
+     * key - value 自减
+     */
+    public static Long decr (String key) {
+        Jedis jedis = null;
+        Long result = null;
+        try {
+            jedis = RedisPool.getJedis();
+            result = jedis.decr(key);
+        } catch (Exception e) {
+            log.error("listGet key:{} error", key, e);
+        } finally {
+            RedisPool.jedisPoolClose(jedis);
+        }
+        return result;
+    }
+
     /**
      * List - get 操作
      */

diff --git a/src/main/java/com/daydreamdev/secondskill/service/impl/OrderServiceImpl.java b/src/main/java/com/daydreamdev/secondskill/service/impl/OrderServiceImpl.java
@@ -1,6 +1,7 @@
 package com.daydreamdev.secondskill.service.impl;
 
 import com.daydreamdev.secondskill.common.RedisKeysConstant;
+import com.daydreamdev.secondskill.common.StockWithRedis.UpdateStockWithRedis;
 import com.daydreamdev.secondskill.common.utils.RedisPoolUtil;
 import com.daydreamdev.secondskill.dao.StockOrderMapper;
 import com.daydreamdev.secondskill.pojo.Stock;
@@ -63,16 +64,51 @@ public int createOrderWithLimitAndRedis(int sid) throws Exception {
     }
 
     /**
-     * Redis 中校验库存（存在少卖问题）
-     * 由于更新数据时，从 Redis Stock 删除，因此存在校验时 Redis 数据为 NULL 的情况
+     * Redis 校验库存
      *
      * @param sid
      */
     private Stock checkStockWithRedis(int sid) throws Exception {
+        Integer count = Integer.parseInt(RedisPoolUtil.get(RedisKeysConstant.STOCK_COUNT + sid));
+        Integer sale = Integer.parseInt(RedisPoolUtil.get(RedisKeysConstant.STOCK_SALE + sid));
+        Integer version = Integer.parseInt(RedisPoolUtil.get(RedisKeysConstant.STOCK_VERSION + sid));
+        if (count <= 0) {
+            log.info("库存不足");
+            throw new RuntimeException("库存不足 Redis currentCount: " + sale);
+        }
+        Stock stock = new Stock();
+        stock.setId(sid);
+        stock.setCount(count);
+        stock.setSale(sale);
+        stock.setVersion(version);
+        // 此处应该是热更新，但是在数据库中只有一个商品，所以直接赋值
+        stock.setName("手机");
+
+        return stock;
+    }
+
+    /**
+     * 更新数据库和 DB，保证一致性
+     */
+    private void saleStockOptimsticWithRedis(Stock stock) throws Exception {
+        int res = stockService.updateStockByOptimistic(stock);
+        if (res == 0){
+            throw new RuntimeException("并发更新库存失败") ;
+        }
+        // 更新 Redis
+        UpdateStockWithRedis.updateStockWithRedis(stock);
+    }
+
+
+    /**
+     * Redis 中校验库存
+     * 由于更新数据时，从 Redis Stock 删除，因此存在校验时 Redis 数据为 NULL 的情况
+     * @param sid
+     */
+    private Stock checkStockWithRedisWithDel(int sid) throws Exception {
         Integer count = null;
         Integer sale = null;
         Integer version = null;
-        // Boolean res = RedisPoolUtil.exists(RedisKeysConstant.STOCK + sid);
         List<String> data = RedisPoolUtil.listGet(RedisKeysConstant.STOCK + sid);
         if (data.size() == 0) {
             // Redis 不存在，先从数据库中获取，再放到 Redis 中
@@ -83,9 +119,6 @@ private Stock checkStockWithRedis(int sid) throws Exception {
             sale = newStock.getSale();
             version = newStock.getVersion();
         } else {
-            if (data.size() == 0 || data.isEmpty()) {
-                log.error("此处报错**************************");
-            }
             count = Integer.parseInt(data.get(0));
             sale = Integer.parseInt(data.get(1));
             version = Integer.parseInt(data.get(2));
@@ -109,7 +142,7 @@ private Stock checkStockWithRedis(int sid) throws Exception {
      * 更新数据库和 Redis 库存
      * 要保证缓存和 DB 的一致性
      */
-    private void saleStockOptimsticWithRedis(Stock stock) throws Exception {
+    private void saleStockOptimsticWithRedisWithDel(Stock stock) throws Exception {
         // 乐观锁更新数据库
         int res = stockService.updateStockByOptimistic(stock);
         // 删除缓存，应该使用 Redis 事务

diff --git a/target/classes/application.properties b/target/classes/application.properties
@@ -21,5 +21,6 @@ redis.maxIdle=100
 redis.maxTotal=300
 redis.maxWait=10000
 redis.testOnBorrow=true
+redis.timeout=100000
 # 限流
 redis.limit=5