20220508_Redisson分布式鎖庫(kù)存扣減學(xué)習(xí)筆記
1概述
本文主要學(xué)習(xí)一下下面的知識(shí)點(diǎn):
- 普通商品數(shù)量的扣減
- 高并發(fā)場(chǎng)景下分布式鎖Redisson的使用確保商品獨(dú)占訪問(wèn)
- 結(jié)合Lua腳本原子性進(jìn)行商品扣庫(kù)存(判斷庫(kù)存數(shù)量與庫(kù)存扣減放在一起執(zhí)行,避免檢測(cè)到有庫(kù)存,然后扣的時(shí)候,已經(jīng)賣(mài)完了的超賣(mài)現(xiàn)象)
2代碼示例
模仿高并發(fā)場(chǎng)景下,三個(gè)商品,100任務(wù)去扣減,每個(gè)任務(wù)扣減數(shù)量為:1。最終只有3個(gè)能成功括饶。
2.1pom依賴(lài)
<!--1.spring-boot-starter-web-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!--2.spring-boot-starter-test-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!--3.redisson-spring-boot-starter分布式鎖-->
<!--最好引用2.13.0 至 3.11.5版本的 redisson-spring-boot-starter-->
<!--內(nèi)置 starter-data-redis,RedisAutoConfiguration 類(lèi)-->
<!--org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,\-->
<!--org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration,\-->
<!--org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration,\-->
<dependency>
<groupId>org.redisson</groupId>
<artifactId>redisson-spring-boot-starter</artifactId>
<!--<version>3.13.1</version>-->
<version>3.11.5</version>
</dependency>
2.2MyRedisConfig
package com.kikop.config;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.*;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import org.springframework.scripting.support.ResourceScriptSource;
/**
* @author kikop
* @version 1.0
* @project myredissiondemo
* @file MyRedisConfig
* @desc MyRedisConfig配置類(lèi)
* @date 2021/3/30
* @time 8:00
* @by IDE IntelliJ IDEA
*/
@Configuration
public class MyRedisConfig {
@Value("${com.kikop.lua.srcript.name}")
private String mygoodsdecy;
/**
* 配置 RedisTemplate模板
* 指定連接工廠,數(shù)據(jù)序列化等關(guān)鍵屬性
*
* @param redisConnectionFactory RedisConnectionFactory怎么由來(lái)的源碼分析 todo
* @return
*/
@Bean
public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
// 1.構(gòu)建 redisTemplate
RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
// 1.1.配置連接工廠
redisTemplate.setConnectionFactory(redisConnectionFactory);
//1.2.構(gòu)建ObjectMapper
ObjectMapper objectMapper = new ObjectMapper();
// 指定要序列化的域，field,get和set,
// 以及修飾符范圍蛉鹿，ANY是都有包括 private和public
objectMapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
// 指定序列化輸入的類(lèi)型，類(lèi)必須是非final修飾的往湿，final修飾的類(lèi)妖异，比如 String,Integer等會(huì)拋出異常
objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL); // 2.1.x
// objectMapper.activateDefaultTyping(LaissezFaireSubTypeValidator.instance, ObjectMapper.DefaultTyping.NON_FINAL); // 2.2.x
// 1.3.使用Jackson2JsonRedisSerializer來(lái)序列化和反序列化
// redis的value值（默認(rèn)使用JDK的序列化方式）
Jackson2JsonRedisSerializer jacksonSeial = new Jackson2JsonRedisSerializer(Object.class);
jacksonSeial.setObjectMapper(objectMapper);
// 1.4.序列化kv
// 使用 StringRedisSerializer來(lái)序列化和反序列化redis的key值
redisTemplate.setKeySerializer(new StringRedisSerializer());
// 值采用json序列化
redisTemplate.setValueSerializer(jacksonSeial);
// 1.5.序列化hash kv
// 設(shè)置hash key 和value序列化模式
redisTemplate.setHashKeySerializer(new StringRedisSerializer());
redisTemplate.setHashValueSerializer(jacksonSeial);
// 1.6.afterPropertiesSet
redisTemplate.afterPropertiesSet();
return redisTemplate;
}
/**
* dataStruct:String
* 對(duì)redis字符串類(lèi)型數(shù)據(jù)操作
*
* @param redisTemplate
* @return
*/
@Bean
public ValueOperations<String, String> stringOperations(StringRedisTemplate redisTemplate) {
return redisTemplate.opsForValue();
}
/**
* 對(duì)POJO類(lèi)型序列化和反序列化操作
* 存儲(chǔ)還是以JSON字符串形式
*
* @param redisTemplate
* @return
*/
@Bean
public ValueOperations<String, Object> valueOperations(RedisTemplate<String, Object> redisTemplate) {
return redisTemplate.opsForValue();
}
/**
* dataStruct:hash
* 對(duì)hash類(lèi)型的數(shù)據(jù)操作
*
* @param redisTemplate
* @return
*/
@Bean
public HashOperations<String, String, Object> hashOperations(RedisTemplate<String, Object> redisTemplate) {
return redisTemplate.opsForHash();
}
/**
* dataStruct:list
* 對(duì)鏈表類(lèi)型的數(shù)據(jù)操作
*
* @param redisTemplate
* @return
*/
@Bean
public ListOperations<String, Object> listOperations(RedisTemplate<String, Object> redisTemplate) {
return redisTemplate.opsForList();
}
/**
* dataStruct:set
* 對(duì)無(wú)序集合類(lèi)型的數(shù)據(jù)操作
*
* @param redisTemplate
* @return
*/
@Bean
public SetOperations<String, Object> setOperations(RedisTemplate<String, Object> redisTemplate) {
return redisTemplate.opsForSet();
}
/**
* dataStruct:zset
* 對(duì)有序集合類(lèi)型的數(shù)據(jù)操作
*
* @param redisTemplate
* @return
*/
@Bean
public ZSetOperations<String, Object> zSetOperations(RedisTemplate<String, Object> redisTemplate) {
return redisTemplate.opsForZSet();
}
/**
* DefaultRedisScript
* 讀取限流腳本
* spring-data-redis.jar
*
* @return
*/
@Bean
public DefaultRedisScript<Number> defaultRedisScript() {
DefaultRedisScript<Number> redisScript = new DefaultRedisScript<>();
// 1.限流腳本位置
redisScript.setScriptSource(new ResourceScriptSource(new ClassPathResource(mygoodsdecy)));
// 2.Lua腳本返回類(lèi)型
redisScript.setResultType(Number.class);
return redisScript;
}
}
2.3RedissionConfig
package com.kikop.config;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.redisson.Redisson;
import org.redisson.api.RedissonClient;
import org.redisson.config.ClusterServersConfig;
import org.redisson.config.Config;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.data.redis.RedisProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.*;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
/**
* @author kikop
* @version 1.0
* @project Name: myredissiondemo
* @file RedissionConfig
* @desc RedissonApplication啟動(dòng)類(lèi)(配置類(lèi))
* http://www.reibang.com/p/59ffff18e1ff
* @date 2021/3/30
* @time 8:00
* @by IDE IntelliJ IDEA
*/
@Configuration
public class RedissionConfig {
@Autowired
private RedisProperties redisProperties;
/**
* 單機(jī)模式
* 構(gòu)建 RedissonClient
* 容器總的Bean名稱(chēng)即為:方法名 redissonClient
* @return
*/
@Bean
public RedissonClient redissonClient() {
Config config = new Config();
// config.useSingleServer().setAddress("redis://ip:port")
// .setPassword("password")
// .setDatabase(0);
String redisAddress = "redis://" + redisProperties.getHost() + ":" + redisProperties.getPort();
config.useSingleServer().setAddress(
// String.format("redis://%s:%s", redisProperties.getHost(), redisProperties.getPort())
redisAddress
)
.setDatabase(0);
RedissonClient redissonClient = Redisson.create(config);
return redissonClient;
}
// /**
// * 哨兵模式
// * 構(gòu)建 RedissonClient
// *
// * @return
// */
//// @Bean
// public RedissonClient sentinelRedissonClient() {
// Config config = new Config();
// config.useSentinelServers().addSentinelAddress("redis://ip1:port1",
// "redis://ip2:port2",
// "redis://ip3:port3")
// .setMasterName("mymaster")
// .setPassword("password")
// .setDatabase(0);
// RedissonClient redissonClient = Redisson.create(config);
// return redissonClient;
// }
//
// /**
// * Cluster集群模式
// * 構(gòu)建 RedissonClient
// *
// * @return
// */
//// @Bean
// public RedissonClient clusterRedissonClient() {
// Config config = new Config();
// ClusterServersConfig clusterServersConfig = config.useClusterServers()
// .setPassword(redisProperties.getPassword())
// .setScanInterval(5000);
//
// // 注冊(cè)集群各個(gè)節(jié)點(diǎn)
// for (String node : redisProperties.getCluster().getNodes()) {
// clusterServersConfig.addNodeAddress("redis://".concat(node));
// }
// RedissonClient redissonClient = Redisson.create(config);
// return redissonClient;
// }
}
2.4mygoodsdecy腳本
-- lua腳本進(jìn)行原子商品扣庫(kù)存操作
-- 返回值,0:失敗;1:成功
-- 由于lua腳本接收到參數(shù)都會(huì)轉(zhuǎn)為String，所以要轉(zhuǎn)成數(shù)字類(lèi)型才能比較
-- 參數(shù)1:商品的key
local key = KEYS[1]
-- 參數(shù)2:扣除庫(kù)存數(shù)量
local amount = tonumber(ARGV[1])
-- 若 key 存在领追，返回 1 他膳，否則返回 0
if redis.call('exists',key) == 0 then -- key不存在
return 0
else
-- 當(dāng)前的庫(kù)存總量
-- 返回 key 所關(guān)聯(lián)的字符串值。
-- 如果 key 不存在那么返回特殊值 nil 绒窑。
-- 假如 key 儲(chǔ)存的值不是字符串類(lèi)型棕孙，返回一個(gè)錯(cuò)誤，因?yàn)?GET 只能用于處理字符串值些膨。
local totalamount = tonumber(redis.call('get',key))
if(amount <= totalamount) then -- 邏輯校驗(yàn),防止超賣(mài)
redis.call('decrby',key,amount)
return 1
end
return 0
end
2.5業(yè)務(wù)實(shí)現(xiàn)
2.5.1模擬商品加載
/**
* 加載商品XXX庫(kù)存入緩存
*
* @param key_goods_001
*/
private void loadGoodsInfo(String key_goods_001) {
// 庫(kù)存總量
int gogal_totalamountLimit = 3;
// 初始化Redis緩存,數(shù)據(jù)類(lèi)型:String
// 1.從數(shù)據(jù)庫(kù)加載來(lái)的,10秒的過(guò)期時(shí)間
// stringRedisTemplate.opsForValue().set(
// key_goods_001,String.valueOf(gogal_totalamountLimit),10,TimeUnit.SECONDS);
// 2.從數(shù)據(jù)庫(kù)加載來(lái)的,設(shè)置永不過(guò)期
// stringRedisTemplate.opsForValue().setIfAbsent(key_goods_001, String.valueOf(gogal_totalamountLimit));
stringRedisTemplate.opsForValue().set(key_goods_001, String.valueOf(gogal_totalamountLimit));
}
2.5.2商品庫(kù)存扣減
2.5.2.1商品庫(kù)存扣減實(shí)現(xiàn)方案1
/**
* 商品庫(kù)存扣減實(shí)現(xiàn)方案1
* 缺點(diǎn):判斷與扣減放在兩個(gè)地方,無(wú)法保證原子性
* 即使增加對(duì)庫(kù)存總量的判斷,容易出現(xiàn)商品負(fù)數(shù)倒賣(mài)
*
* @param lock_goods_001
* @param key_goods_001
* @param descAmount https://blog.csdn.net/qq_41534566/article/details/79219023
*/
public void descryGoodsNoLock(String lock_goods_001, String key_goods_001, int descAmount) {
try {
// 3.庫(kù)存扣減業(yè)務(wù)操作
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "開(kāi)始扣庫(kù)存...");
String currentAmount = stringRedisTemplate.opsForValue().get(key_goods_001);
// 3.1方法一
// 判斷與扣減放在兩個(gè)地方,無(wú)法保證原子性
// 即使增加對(duì)庫(kù)存總量的判斷,容易出現(xiàn)商品負(fù)數(shù)倒賣(mài)
if (descAmount <= Integer.valueOf(currentAmount)) { // 判斷
stringRedisTemplate.opsForValue().decrement(key_goods_001, descAmount); // 扣減
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "恭喜你,買(mǎi)到大寶貝了,扣庫(kù)存成功!");
} else {
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "大寶貝賣(mài)完了,扣庫(kù)存失敗!");
}
// 4.庫(kù)存查詢(xún)
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "當(dāng)前庫(kù)存剩余數(shù)量:" + currentAmount);
} finally {
}
}
2.5.2.2商品庫(kù)存扣減實(shí)現(xiàn)方案2
/**
* 商品庫(kù)存扣減實(shí)現(xiàn)方案2
* 增加RedissonLock分布式鎖
*
* @param lock_goods_001
* @param key_goods_001
* @param descAmount https://blog.csdn.net/qq_41534566/article/details/79219023
*/
public void descryGoodsByLock(String lock_goods_001, String key_goods_001, int descAmount) {
RLock rLock = null;
try {
// 1.構(gòu)建鎖 RLock
// 如場(chǎng)景:
// 過(guò)獨(dú)木橋,
// 發(fā)票卡口蟀俊。
rLock = redissonClient.getLock(lock_goods_001);
// 2.獲取某任務(wù)鎖 by lua,如果獲取不到鎖,則一直阻塞(對(duì)比tryLock)
// 內(nèi)置自動(dòng)續(xù)命的功能,leaseTime:-1
rLock.lock();
// 3.庫(kù)存扣減業(yè)務(wù)操作
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "開(kāi)始扣庫(kù)存...");
String currentAmount = stringRedisTemplate.opsForValue().get(key_goods_001);
// 3.1方法一
// 判斷與扣減放在兩個(gè)地方,無(wú)法保證原子性
// 缺少對(duì)庫(kù)存總量的判斷,容易出現(xiàn)商品負(fù)數(shù)倒賣(mài)
if (descAmount <= Integer.valueOf(currentAmount)) { // 判斷
stringRedisTemplate.opsForValue().decrement(key_goods_001, descAmount); // 扣減
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "恭喜你,買(mǎi)到大寶貝了,扣庫(kù)存成功!");
} else {
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "大寶貝賣(mài)完了,扣庫(kù)存失敗!");
}
// 4.庫(kù)存查詢(xún)
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "當(dāng)前庫(kù)存剩余數(shù)量:" + currentAmount);
} finally {
if (rLock != null && rLock.isHeldByCurrentThread()) {
rLock.unlock();
}
}
}
2.5.2.3商品庫(kù)存扣減實(shí)現(xiàn)方案3
/**
* 商品庫(kù)存扣減實(shí)現(xiàn)方案3
* 增加RedissonLock分布式鎖、扣減庫(kù)存通過(guò)Lua腳本執(zhí)行
*
* @param lock_goods_001
* @param key_goods_001
* @param descAmount https://blog.csdn.net/qq_41534566/article/details/79219023
*/
public void descryGoodsByLockAndLua(String lock_goods_001, String key_goods_001, int descAmount) {
RLock rLock = null;
try {
// 1.構(gòu)建鎖 RLock
// 如場(chǎng)景:
// 過(guò)獨(dú)木橋,
// 發(fā)票卡口订雾。
rLock = redissonClient.getLock(lock_goods_001);
// 2.獲取某任務(wù)鎖 by lua,如果獲取不到鎖,則一直阻塞(對(duì)比tryLock)
// 內(nèi)置自動(dòng)續(xù)命的功能,leaseTime:-1
rLock.lock();
// 3.庫(kù)存扣減業(yè)務(wù)操作
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "開(kāi)始扣庫(kù)存...");
String currentAmount = stringRedisTemplate.opsForValue().get(key_goods_001);
// 3.2.方法二
// 解決辦法:
// 判斷是否有余量庫(kù)存與扣除動(dòng)作保持原子性,放在lua腳本里即可肢预。
List<String> keys = Arrays.asList(key_goods_001);
Number execResult = stringRedisTemplate.execute(defaultRedisScript, keys, String.valueOf(descAmount));
if (null == execResult || execResult.intValue() == 0) {
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "大寶貝賣(mài)完了,扣庫(kù)存失敗!");
} else {
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "恭喜你,買(mǎi)到大寶貝了,扣庫(kù)存成功!");
}
// 4.庫(kù)存查詢(xún)
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "當(dāng)前庫(kù)存剩余數(shù)量:" + currentAmount);
} finally {
if (rLock != null && rLock.isHeldByCurrentThread()) {
rLock.unlock();
}
}
}
2.6完整代碼及測(cè)試
package com.kikop;
import com.kikop.util2.MyDateUtil;
import lombok.extern.slf4j.Slf4j;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.annotation.Bean;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.function.IntConsumer;
import java.util.stream.IntStream;
/**
* @author kikop
* @version 1.0
* @project myredissiondemo
* @file RedissonApplicationTests
* @desc
* @date 2021/3/30
* @time 8:00
* @by IDE IntelliJ IDEA
*/
@RunWith(SpringRunner.class)
@SpringBootTest
@Slf4j
public class GoodRepoApplicationTest {
// 1.訪問(wèn)商品庫(kù)存的鎖
@Autowired
private RedissonClient redissonClient;
// 2.操作商品庫(kù)存扣減
@Autowired
StringRedisTemplate stringRedisTemplate;
@Autowired
private DefaultRedisScript<Number> defaultRedisScript;
// Redisson分布式鎖
// 對(duì)應(yīng) 某具體商品XXX
private final String LOCK_GOODS_ADD_PREFIX = "lock:goods:decry:";
// 對(duì)應(yīng)某具體商品XXX的庫(kù)存key
private final String KEY_GOODS_ADD_PREFIX = "key:goods:";
/**
* 加載商品XXX庫(kù)存入緩存
*
* @param key_goods_001
*/
private void loadGoodsInfo(String key_goods_001) {
// 庫(kù)存總量
int gogal_totalamountLimit = 3;
// 初始化Redis緩存,數(shù)據(jù)類(lèi)型:String
// 1.從數(shù)據(jù)庫(kù)加載來(lái)的,10秒的過(guò)期時(shí)間
// stringRedisTemplate.opsForValue().set(
// key_goods_001,String.valueOf(gogal_totalamountLimit),10,TimeUnit.SECONDS);
// 2.從數(shù)據(jù)庫(kù)加載來(lái)的,設(shè)置永不過(guò)期
// stringRedisTemplate.opsForValue().setIfAbsent(key_goods_001, String.valueOf(gogal_totalamountLimit));
stringRedisTemplate.opsForValue().set(key_goods_001, String.valueOf(gogal_totalamountLimit));
}
/**
* 商品庫(kù)存扣減實(shí)現(xiàn)方案1
* 缺點(diǎn):判斷與扣減放在兩個(gè)地方,無(wú)法保證原子性
* 即使增加對(duì)庫(kù)存總量的判斷,容易出現(xiàn)商品負(fù)數(shù)倒賣(mài)
*
* @param lock_goods_001
* @param key_goods_001
* @param descAmount https://blog.csdn.net/qq_41534566/article/details/79219023
*/
public void descryGoodsNoLock(String lock_goods_001, String key_goods_001, int descAmount) {
try {
// 3.庫(kù)存扣減業(yè)務(wù)操作
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "開(kāi)始扣庫(kù)存...");
String currentAmount = stringRedisTemplate.opsForValue().get(key_goods_001);
// 3.1方法一
// 判斷與扣減放在兩個(gè)地方,無(wú)法保證原子性
// 即使增加對(duì)庫(kù)存總量的判斷,容易出現(xiàn)商品負(fù)數(shù)倒賣(mài)
if (descAmount <= Integer.valueOf(currentAmount)) { // 判斷
stringRedisTemplate.opsForValue().decrement(key_goods_001, descAmount); // 扣減
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "恭喜你,買(mǎi)到大寶貝了,扣庫(kù)存成功!");
} else {
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "大寶貝賣(mài)完了,扣庫(kù)存失敗!");
}
// 4.庫(kù)存查詢(xún)
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "當(dāng)前庫(kù)存剩余數(shù)量:" + currentAmount);
} finally {
}
}
/**
* 商品庫(kù)存扣減實(shí)現(xiàn)方案2
* 增加RedissonLock分布式鎖
*
* @param lock_goods_001
* @param key_goods_001
* @param descAmount https://blog.csdn.net/qq_41534566/article/details/79219023
*/
public void descryGoodsByLock(String lock_goods_001, String key_goods_001, int descAmount) {
RLock rLock = null;
try {
// 1.構(gòu)建鎖 RLock
// 如場(chǎng)景:
// 過(guò)獨(dú)木橋,
// 發(fā)票卡口。
rLock = redissonClient.getLock(lock_goods_001);
// 2.獲取某任務(wù)鎖 by lua,如果獲取不到鎖,則一直阻塞(對(duì)比tryLock)
// 內(nèi)置自動(dòng)續(xù)命的功能,leaseTime:-1
rLock.lock();
// 3.庫(kù)存扣減業(yè)務(wù)操作
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "開(kāi)始扣庫(kù)存...");
String currentAmount = stringRedisTemplate.opsForValue().get(key_goods_001);
// 3.1方法一
// 判斷與扣減放在兩個(gè)地方,無(wú)法保證原子性
// 缺少對(duì)庫(kù)存總量的判斷,容易出現(xiàn)商品負(fù)數(shù)倒賣(mài)
if (descAmount <= Integer.valueOf(currentAmount)) { // 判斷
stringRedisTemplate.opsForValue().decrement(key_goods_001, descAmount); // 扣減
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "恭喜你,買(mǎi)到大寶貝了,扣庫(kù)存成功!");
} else {
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "大寶貝賣(mài)完了,扣庫(kù)存失敗!");
}
// 4.庫(kù)存查詢(xún)
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "當(dāng)前庫(kù)存剩余數(shù)量:" + currentAmount);
} finally {
if (rLock != null && rLock.isHeldByCurrentThread()) {
rLock.unlock();
}
}
}
/**
* 商品庫(kù)存扣減實(shí)現(xiàn)方案3
* 增加RedissonLock分布式鎖洼哎、扣減庫(kù)存通過(guò)Lua腳本執(zhí)行
*
* @param lock_goods_001
* @param key_goods_001
* @param descAmount https://blog.csdn.net/qq_41534566/article/details/79219023
*/
public void descryGoodsByLockAndLua(String lock_goods_001, String key_goods_001, int descAmount) {
RLock rLock = null;
try {
// 1.構(gòu)建鎖 RLock
// 如場(chǎng)景:
// 過(guò)獨(dú)木橋,
// 發(fā)票卡口烫映。
rLock = redissonClient.getLock(lock_goods_001);
// 2.獲取某任務(wù)鎖 by lua,如果獲取不到鎖,則一直阻塞(對(duì)比tryLock)
// 內(nèi)置自動(dòng)續(xù)命的功能,leaseTime:-1
rLock.lock();
// 3.庫(kù)存扣減業(yè)務(wù)操作
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "開(kāi)始扣庫(kù)存...");
String currentAmount = stringRedisTemplate.opsForValue().get(key_goods_001);
// 3.2.方法二
// 解決辦法:
// 判斷是否有余量庫(kù)存與扣除動(dòng)作保持原子性,放在lua腳本里即可。
List<String> keys = Arrays.asList(key_goods_001);
Number execResult = stringRedisTemplate.execute(defaultRedisScript, keys, String.valueOf(descAmount));
if (null == execResult || execResult.intValue() == 0) {
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "大寶貝賣(mài)完了,扣庫(kù)存失敗!");
} else {
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "恭喜你,買(mǎi)到大寶貝了,扣庫(kù)存成功!");
}
// 4.庫(kù)存查詢(xún)
System.out.println(MyDateUtil.getCurrentDateStrByDefaultFormat() + "," + "當(dāng)前庫(kù)存剩余數(shù)量:" + currentAmount);
} finally {
if (rLock != null && rLock.isHeldByCurrentThread()) {
rLock.unlock();
}
}
}
@Test
public void testGoodsMiaoSha() throws InterruptedException {
// 根據(jù)商品ID控制商品鎖的粒度要小
// XXX號(hào)商品鎖(只是起個(gè)鎖的名字)
String lock_goods_001 = LOCK_GOODS_ADD_PREFIX + "000001";
// XXX號(hào)商品在Redis緩存中的key
String key_goods_001 = KEY_GOODS_ADD_PREFIX + "000001";
loadGoodsInfo(key_goods_001);
int threads_num = 100;
CountDownLatch countDownLatch = new CountDownLatch(threads_num);
// 多個(gè)線程 forkJoinPool并發(fā)去獲取鎖
IntStream.range(0, threads_num).parallel().forEach(new IntConsumer() {
@Override
public void accept(int i) {
// 假設(shè)每次消耗庫(kù)存數(shù)為1
int descAmount = 1;
GoodRepoApplicationTest.this.descryGoodsByLock(lock_goods_001, key_goods_001, descAmount);
countDownLatch.countDown();
}
});
// 等待任務(wù)執(zhí)行完,主線程在退出
countDownLatch.await();
}
/**
* Lua腳本測(cè)試
*/
@Test
public void testGoodsDecryByLua() {
// XXX號(hào)商品在Redis緩存中的key
String key_goods_001 = KEY_GOODS_ADD_PREFIX + "000001";
// 假設(shè)每次消耗庫(kù)存數(shù)為1
int descAmount = 1;
List<String> keys = Arrays.asList(key_goods_001);
Number execResult = stringRedisTemplate.execute(defaultRedisScript, keys, String.valueOf(descAmount));
System.out.println(execResult.intValue());
}
}
3總結(jié)
3.1方案2Redisson鎖是否必要
必要,否則會(huì)出現(xiàn)方案1的商品超賣(mài)情況噩峦。
3.2方案3Redisson鎖是否必要
不必要,因?yàn)長(zhǎng)ua腳本已經(jīng)控制了共享資源的獨(dú)占訪問(wèn)锭沟，并且確保不會(huì)出現(xiàn)超賣(mài)現(xiàn)象。
