Redis+Lua脚本+AOP+自定义注解自定义基础限流组件

背景

项目中很多接口是有防重防刷要求的，比如下单啊、支付啊这种，如果用户频繁的点，后端没做好保护的话，很容易出问题

市面上有主流的一体化解决方案，比如 resilience4j啊，比如 Sentinel，但是有些公司有要求不允许引入这些第三方库，又该如何应对呢

限流组件设计目标

Redis+Lua脚本+AOP+反射+自定义注解，打造基础架构限流组件，对于限流组件的设计，总体要求是：

可配置：也就是规定时间内，可以随意调整时间和次数

可插拔：就像上面那个注解，接口加了注解自带限流功能，不加注解没有限流

可通用：不能业务代码耦合，可独立模块，供其它团队使用

高可用：高并发下实时起效

环境搭建

这里使用 SpringBoot3+Redis 快速搭建项目骨架

xml 复制代码

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>3.3.0</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example.springbootV3</groupId>
	<artifactId>springbootV3</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>springbootV3</name>
	<properties>
		<java.version>17</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
			<version>3.1.3</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-aop</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-redis</artifactId>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>
</project>

采购 AOP 注解形式(如下注解表示10s内最多支持3次访问，到了3次后开启限流，过完本次10s后才解封放开，可以重新访问)

java 复制代码

@RestController
@RequestMapping("/limit")
public class RedisLimitController {
    @GetMapping("/redis/test")
    @RedisLimitAnnotation(key = "redisLimit", permitsPerSecond = 3, expire = 10, msg = "当前访问人数较多，请稍后重试")
    public String redisLimit() {
        return "正常业务返回，" + UUID.randomUUID().toString();
    }
}

yaml 复制代码

spring.data.redis.database=0
spring.data.redis.host=192.168.133.128
spring.data.redis.port=6379
spring.data.redis.password=123456
spring.data.redis.lettuce.pool.max-active=8
spring.data.redis.lettuce.pool.max-wait=-1ms
spring.data.redis.lettuce.pool.max-idle=8
spring.data.redis.lettuce.pool.min-idle=0

java 复制代码

@Configuration
public class RedisConfig {
    @Bean
    public RedisTemplate<String, Object> redisTemplate(LettuceConnectionFactory lettuceConnectionFactory) {
        RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(lettuceConnectionFactory);
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(new GenericJackson2JsonRedisSerializer());
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashValueSerializer(new GenericJackson2JsonRedisSerializer());
        redisTemplate.afterPropertiesSet();
        return redisTemplate;
    }
}

接下来主要就是 @RedisLimitAnnotation 注解及切面的设计开发了

注解及切面

java 复制代码

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Documented
public @interface RedisLimitAnnotation {
    // 资源 key，唯一
    String key() default "";

    // 最多的访问次数限制
    long permitsPerSecond() default 3;

    // 过期时间，单位秒默认30s
    long expire() default 30;

    // 默认提示
    String msg() default "你点击太快，请稍后再搞.";
}

java 复制代码

@Slf4j
@Aspect
@Component
public class RdisLimitAspect {
    Object result = null;
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    private DefaultRedisScript<Long> redisScript;

    @PostConstruct
    public void init(){
        redisScript = new DefaultRedisScript<>();
        redisScript.setResultType(Long.class);
        redisScript.setScriptSource(new ResourceScriptSource(new ClassPathResource("rateLimiter.lua")));
    }

    @Around("@annotation(com.example.demo.annotation.RedisLimitAnnotation)")
    public Object around(ProceedingJoinPoint pjg) {
        System.out.println("环绕通知开始..");
        MethodSignature signature = (MethodSignature) pjg.getSignature();
        Method method = signature.getMethod();
        RedisLimitAnnotation annotation = method.getAnnotation(RedisLimitAnnotation.class);
        if (annotation != null) {
            String key = annotation.key(); // 获取 redis的 key
            String className = method.getDeclaringClass().getName();
            String methodName = method.getName();
            String limitKey = key + "\t" + className + "\t" + methodName;
            log.info(limitKey);
            if (key == null) {
                throw new RuntimeException("limitkey can not be null");
            }
            long permitsPerSecond = annotation.permitsPerSecond();
            long expire = annotation.expire();
            List<String> keys = new ArrayList<>();
            keys.add(key);
            Long count = stringRedisTemplate.execute(redisScript, keys, String.valueOf(permitsPerSecond), String.valueOf(expire));
            if (count != null && count == 0) {
                System.out.println("气东送限流功能key：" + key);
                return annotation.msg();
            }
        }
        try {
            result = pjg.proceed();
        } catch (Throwable throwable) {
            throw new RuntimeException(throwable);
        }
        System.out.println("环绕通知结束..");
        return result;
    }
}

最后是 Lua 脚本

lua 复制代码

local key = KEYS[1]
local limit = tonumber(ARGV[1])
local currentLimit = tonumber(redis.call('get', key) or "0")
if currentLimit + 1 > limit
then return 0
else
  redis.call('INCRBY', key, 1)
  redis.call('EXPIRE', key, ARGV[2])
  return currentLimit + 1
end

最后效果如下