redis限流

电玩女神 2023-06-18 11:00 27阅读 0赞

计数器限流，时间段一个计数器，超过指定值，就返回错误。  
lua保证操作原子性。  
zuul网关中，使用过滤器限流。

/** * 限流 * @author lipo * @version v1.0 * @date 2019-10-25 10:34 */
    @Slf4j
    @Component
    public class LimitFilter extends OncePerRequestFilter { 
        /** * 1。查询key，如果不存在，就创建key * 2。计数器+1，查出来 * 3。计数器>限定值，返回true，限流；否则，返回false，不限流 */
    
        private static final String LUA_SCRIPT = "local count = redis.call('GET', KEYS[1])\n" +
                        "if not count then\n" +
                        " redis.call('SET', KEYS[1], 1, 'EX', ARGV[1])\n" +
                        " return false\n" +
                        "end\n" +
    
                        "redis.call('INCR', KEYS[1])\n" +
                        "if (count + 1 > tonumber(ARGV[2])) then\n" +
                        " return true\n" +
                        "end\n" +
    
                        "return false\n"
                ;
    
        private final RedisScript<Boolean> redisScript = new DefaultRedisScript<>(LUA_SCRIPT, Boolean.class);
    
        @Autowired
        private StringRedisTemplate stringRedisTemplate;
    
        @Override
        protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { 
            //过滤图标请求
            String requestUri = request.getRequestURI();
            if ("/favicon.ico".equals(requestUri)) { 
                return;
            }
    
            RequestWrapper requestWrapper = new RequestWrapper(request);
            ResponseWrapper responseWrapper = new ResponseWrapper(response);
    
            boolean b = limitFlow();
            if (b) { 
                String result = "请求繁忙，已限流";
                log.error(result);
                responseWrapper.responseMessage(result);
                return;
            }
    
            filterChain.doFilter(requestWrapper, responseWrapper);
        }
    
        private boolean limitFlow() { 
            Boolean limit10 = stringRedisTemplate.execute(redisScript, Collections.singletonList("LIMIT10"), "10", "3");
            if (Boolean.TRUE.equals(limit10)) { 
                return true;
            }
    
            Boolean limit100 = stringRedisTemplate.execute(redisScript, Collections.singletonList("LIMIT100"), "100", "5");
            return Boolean.TRUE.equals(limit100);
        }
    
    }

项目https://github.com/mingwulipo/cloud-demo.git