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redis+lua+固定窗口实现分布式限流

news 2025/4/29 5:56:40

用key的过期时间替代固定窗口的时间戳

-- KEYS[1]: 限流的key
-- ARGV[1]: 限流窗口大小（秒）
-- ARGV[2]: 限流阈值local key = KEYS[1]
local window = tonumber(ARGV[1])
local limit = tonumber(ARGV[2])-- 尝试获取当前计数
local current = redis.call("GET", key)if current == false then-- key不存在，初始化计数器并设置过期时间redis.call("SET", key, 1, "EX", window)return 1
else-- key存在，检查是否超过限制if tonumber(current) < limit thenredis.call("INCR", key)return 1elsereturn 0end
end

java客户端

public class FixedWindowRateLimiterWithTTL {private Jedis jedis;private String key;private int window; // 窗口大小（秒）private int limit;  // 限流阈值private static final String LUA_SCRIPT ="local key = KEYS[1]\n" +"local window = tonumber(ARGV[1])\n" +"local limit = tonumber(ARGV[2])\n" +"local current = redis.call(\"GET\", key)\n" +"if current == false then\n" +"    redis.call(\"SET\", key, 1, \"EX\", window)\n" +"    return 1\n" +"else\n" +"    if tonumber(current) < limit then\n" +"        redis.call(\"INCR\", key)\n" +"        return 1\n" +"    else\n" +"        return 0\n" +"    end\n" +"end";public FixedWindowRateLimiterWithTTL(Jedis jedis, String key, int window, int limit) {this.jedis = jedis;this.key = key;this.window = window;this.limit = limit;}public boolean allowRequest() {Object result = jedis.eval(LUA_SCRIPT, Collections.singletonList(key),Arrays.asList(String.valueOf(window),String.valueOf(limit)));return "1".equals(result.toString());}
}

使用

public static void main(String[] args) {Jedis jedis = new Jedis("localhost");// 创建一个每分钟最多100次请求的限流器FixedWindowRateLimiterWithTTL limiter = new FixedWindowRateLimiterWithTTL(jedis, "api:limit:user1", 60, 100);for (int i = 0; i < 120; i++) {if (limiter.allowRequest()) {System.out.println("处理请求 " + i);} else {System.out.println("限流请求 " + i);}}jedis.close();
}