基于 Redis + Lua 脚本实现分布式锁，确保操作的原子性

比眉伴天荒 2024-02-20 08:53 8阅读 0赞

##### 1.加锁的Lua脚本： lock.lua #####

--- -1 failed
    --- 1 success
    
    --- getLock key
    local result = redis.call('setnx' , KEYS[1] , ARGV[1])
    if result == 1 then
        --PEXPIRE:以毫秒的形式指定过期时间
        redis.call('pexpire' , KEYS[1] , 3600000)
    else
        result = -1;
        -- 如果value相同，则认为是同一个线程的请求，则认为重入锁
        local value = redis.call('get' , KEYS[1])
        if (value == ARGV[1]) then
            result = 1;
            redis.call('pexpire' , KEYS[1] , 3600000)
        end
    end
    --  如果获取锁成功，则返回 1
    return result

##### 2.解锁的Lua脚本： unLock.lua #####

if redis.call('get', KEYS[1]) == ARGV[1]
        then
            return redis.call('del', KEYS[1])
        else
            return 0
    end

##### 3.将资源文件放在资源文件夹下 #####

![3fb60a17b4e9473ebf7fe7c2934727ef.png][]

##### 4.Java中调用lua脚本 #####

1）获取文件方式

import lombok.extern.slf4j.Slf4j;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.core.io.ClassPathResource;
    import org.springframework.data.redis.core.RedisTemplate;
    import org.springframework.data.redis.core.script.DefaultRedisScript;
    import org.springframework.scripting.support.ResourceScriptSource;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.Arrays;
    
    /**
     * @Author: best_liu
     * @Description:
     * @Date Create in 14:04 2023/10/26
     * @Modified By:
     */
    @Slf4j
    @RestController
    public class LuaLock {
    
    
        @Autowired
        private RedisTemplate redisTemplate;
    
        @GetMapping(value = "/getLock")
        public Long getLock() {
            DefaultRedisScript<Long> script = new DefaultRedisScript<Long>();
            script.setResultType(Long.class);
    //        获取lua文件方式
            script.setScriptSource(new ResourceScriptSource(new ClassPathResource("script/lock.lua")));
            
            Long execute = (Long) redisTemplate.execute(script, Arrays.asList("best_liu"),"best_liu20231026150600");
            return execute;
        }
    }

2）lua字符串方式

import lombok.extern.slf4j.Slf4j;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.data.redis.core.RedisTemplate;
    import org.springframework.data.redis.core.script.DefaultRedisScript;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.Arrays;
    
    /**
     * @Author: best_liu
     * @Description:
     * @Date Create in 14:04 2023/10/26
     * @Modified By:
     */
    @Slf4j
    @RestController
    public class LuaLock {
    
    
        @Autowired
        private RedisTemplate redisTemplate;
    
        @GetMapping(value = "/getLock")
        public Long getLock() {
            DefaultRedisScript<Long> script = new DefaultRedisScript<Long>();
            script.setResultType(Long.class);
    //        获取lua文件方式
    //        script.setScriptSource(new ResourceScriptSource(new ClassPathResource("script/lock.lua")));
            String lua = "local result = redis.call('setnx' , KEYS[1] , ARGV[1])\n" +
                    "if result == 1 then\n" +
                    "    redis.call('pexpire' , KEYS[1] , 3600000)\n" +
                    "else\n" +
                    "    result = -1;\n" +
                    "    local value = redis.call('get' , KEYS[1])\n" +
                    "    if (value == ARGV[1]) then\n" +
                    "        result = 1;\n" +
                    "        redis.call('pexpire' , KEYS[1] , 3600000)\n" +
                    "    end\n" +
                    "end\n" +
                    "return result";
            script.setScriptText(lua);
            Long execute = (Long) redisTemplate.execute(script, Arrays.asList("best_liu"),"best_liu20231026150600");
            return execute;
        }
    }

##### 5.jedis调用Lua脚本实现分布式重试锁 #####

1）引入jedis依赖

<dependency>
                <groupId>redis.clients</groupId>
                <artifactId>jedis</artifactId>
                <version>2.9.0</version>
            </dependency>

2）jedis调用lua

import lombok.extern.slf4j.Slf4j;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RestController;
    import redis.clients.jedis.Jedis;
    
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.List;
    
    @Slf4j
    @RestController
    public class LuaLock {
    
    
        @GetMapping(value = "/getLock")
        public Long getLock() {
            //获取连接
            Jedis jedis = new Jedis("127.0.0.1", 6379);
            String lua = "local result = redis.call('setnx' , KEYS[1] , ARGV[1])\n" +
                    "if result == 1 then\n" +
                    "    redis.call('pexpire' , KEYS[1] , ARGV[2])\n" +
                    "else\n" +
                    "    result = -1;\n" +
                    "    local value = redis.call('get' , KEYS[1])\n" +
                    "    if (value == ARGV[1]) then\n" +
                    "        result = 1;\n" +
                    "        redis.call('pexpire' , KEYS[1] , ARGV[2])\n" +
                    "    end\n" +
                    "end\n" +
                    "return result";
            List<String> keys = new ArrayList<>();
            List<String> values = new ArrayList<>();
            keys.add("best_liu");
            values.add("best_liu20231026150600");
            values.add("3600000");
            Object result = jedis.eval(lua, keys, values);
            System.out.println(result);
            return 1L;
        }
    }

[3fb60a17b4e9473ebf7fe7c2934727ef.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/20/9f32ceee89cd40b49beb80998b0b22f6.png