基于redis+lua脚本实现限流

 private void waitForToken(String tenantId) throws InterruptedException {
        String key = RATE_LIMIT_KEY_PREFIX + tenantId;
        long maxTokens = 5; // 最大令牌数
        long refillInterval = 1000; // 令牌补充间隔(ms)
        
        while (true) {
            // 使用 Lua 脚本保证原子性
            String luaScript = 
                "local current_tokens = redis.call('GET', KEYS[1])\n" +
                "local last_refill_time = redis.call('GET', KEYS[2])\n" +
                "local now = tonumber(ARGV[1])\n" +
                "local max_tokens = tonumber(ARGV[2])\n" +
                "local refill_interval = tonumber(ARGV[3])\n" +
                "\n" +
                "if current_tokens == false then\n" +
                "    redis.call('SET', KEYS[1], max_tokens - 1)\n" +
                "    redis.call('SET', KEYS[2], now)\n" +
                "    return 1\n" +
                "end\n" +
                "\n" +
                "current_tokens = tonumber(current_tokens)\n" +
                "last_refill_time = tonumber(last_refill_time)\n" +
                "\n" +
                "local tokens_to_add = math.floor((now - last_refill_time) / refill_interval)\n" +
                "if tokens_to_add > 0 then\n" +
                "    current_tokens = math.min(max_tokens, current_tokens + tokens_to_add)\n" +
                "    last_refill_time = now\n" +
                "end\n" +
                "\n" +
                "if current_tokens > 0 then\n" +
                "    redis.call('SET', KEYS[1], current_tokens - 1)\n" +
                "    redis.call('SET', KEYS[2], last_refill_time)\n" +
                "    return 1\n" +
                "else\n" +
                "    return 0\n" +
                "end";
            
            List<String> keys = Arrays.asList(key, key + ":last_refill");
            List<String> args = Arrays.asList(
                String.valueOf(System.currentTimeMillis()),
                String.valueOf(maxTokens),
                String.valueOf(refillInterval)
            );
            
            Long result = stringRedisTemplate.execute(
                new DefaultRedisScript<>(luaScript, Long.class),
                keys,
                args.toArray(new String[0])
            );
            
            if (result != null && result == 1) {
                // 获取到令牌
                break;
            } else {
                // 没有获取到令牌，等待一段时间后重试
                Thread.sleep(100);
            }
        }
    }
    
    /**
     * 归还令牌（可选，根据业务需求决定是否需要）
     * @param tenantId 租户ID
     */
    private void returnToken(String tenantId) {
        try {
            String key = RATE_LIMIT_KEY_PREFIX + tenantId;
            String luaScript = 
                "local current_tokens = redis.call('GET', KEYS[1])\n" +
                "local max_tokens = tonumber(ARGV[1])\n" +
                "\n" +
                "if current_tokens ~= false then\n" +
                "    current_tokens = tonumber(current_tokens)\n" +
                "    if current_tokens < max_tokens then\n" +
                "        redis.call('SET', KEYS[1], current_tokens + 1)\n" +
                "    end\n" +
                "end";
            
            stringRedisTemplate.execute(
                new DefaultRedisScript<>(luaScript),
                Arrays.asList(key),
                String.valueOf(5)
            );
        } catch (Exception e) {
            log.warn("归还令牌失败，tenantId={}", tenantId, e);
        }
    }
}