一文聊聊Redis中的限流策略

public?class?redisLimiterTest?{ ????private?Jedis?jedis;  ????public?RedisLimiterTest(Jedis?jedis)?{ ????????this.jedis?=?jedis; ????}  ????/** ?????*?@param?ipAddress?Ip地址 ?????*?@param?period????特定的時間內，單位秒 ?????*?@param?maxCount??最大允許的次數 ?????*?@return ?????*/ ????public?boolean?isIpLimit(String?ipAddress,?int?period,?int?maxCount)?{ ????????String?key?=?String.format("ip:%s",?ipAddress); ????????//?毫秒時間戳 ????????long?currentTimeMillis?=?System.currentTimeMillis(); ????????Pipeline?pipe?=?jedis.pipelined(); ????????//?redis事務，保證原子性 ????????pipe.multi(); ????????//?存放數據，value?和?score?都使用毫秒時間戳 ????????pipe.zadd(key,?currentTimeMillis,?""?+?UUID.randomUUID()); ????????//?移除窗口區間所有的元素 ????????pipe.zremrangeByScore(key,?0,?currentTimeMillis?-?period?*?1000); ????????//?獲取時間窗口內的行為數量 ????????Response<long>?count?=?pipe.zcard(key); ????????//?設置?zset?過期時間，避免冷用戶持續占用內存，這里寬限1s ????????pipe.expire(key,?period?+?1); ????????//?提交事務 ????????pipe.exec(); ????????pipe.close(); ????????//?比較數量是否超標 ????????return?count.get()?&gt;?maxCount; ????}  ????public?static?void?main(String[]?args)?{ ????????Jedis?jedis?=?new?Jedis("localhost",?6379); ????????RedisLimiterTest?limiter?=?new?RedisLimiterTest(jedis); ????????for?(int?i?=?1;?i?<p><strong>執行結果</strong></p> <pre class="brush:js;toolbar:false;">訪問第1次,?結果：允許訪問 訪問第2次,?結果：允許訪問 訪問第3次,?結果：允許訪問 訪問第4次,?結果：允許訪問 訪問第5次,?結果：允許訪問 訪問第6次,?結果：限制訪問 訪問第7次,?結果：限制訪問 ...?...

public?class?FunnelLimiterTest?{  ????static?class?Funnel?{ ????????int?capacity;?//?漏斗容量 ????????float?leakingRate;?//?漏嘴流水速率 ????????int?leftQuota;?//?漏斗剩余空間 ????????long?leakingTs;?//?上一次漏水時間  ????????public?Funnel(int?capacity,?float?leakingRate)?{ ????????????this.capacity?=?capacity; ????????????this.leakingRate?=?leakingRate; ????????????this.leftQuota?=?capacity; ????????????this.leakingTs?=?System.currentTimeMillis(); ????????}  ????????void?makeSpace()?{ ????????????long?nowTs?=?System.currentTimeMillis(); ????????????long?deltaTs?=?nowTs?-?leakingTs;?//?距離上一次漏水過去了多久 ????????????int?deltaQuota?=?(int)?(deltaTs?*?leakingRate);?//?騰出的空間?=?時間*漏水速率 ????????????if?(deltaQuota??this.capacity)?{?//?剩余空間不得高于容量 ????????????????this.leftQuota?=?this.capacity; ????????????} ????????}  ????????boolean?watering(int?quota)?{ ????????????makeSpace(); ????????????if?(this.leftQuota?&gt;=?quota)?{?//?判斷剩余空間是否足夠 ????????????????this.leftQuota?-=?quota; ????????????????return?true; ????????????} ????????????return?false; ????????} ????}  ????//?所有的漏斗 ????private?Map<string>?funnels?=?new?HashMap();  ????/** ?????*?@param?capacity????漏斗容量 ?????*?@param?leakingRate?漏嘴流水速率?quota/s ?????*/ ????public?boolean?isIpLimit(String?ipAddress,?int?capacity,?float?leakingRate)?{ ????????String?key?=?String.format("ip:%s",?ipAddress); ????????Funnel?funnel?=?funnels.get(key); ????????if?(funnel?==?null)?{ ????????????funnel?=?new?Funnel(capacity,?leakingRate); ????????????funnels.put(key,?funnel); ????????} ????????return?!funnel.watering(1);?//?需要1個quota ????}  ????public?static?void?main(String[]?args)?throws?Exception{ ????????FunnelLimiterTest?limiter?=?new?FunnelLimiterTest(); ????????for?(int?i?=?1;?i?<p><strong>執行結果</strong></p> <pre class="brush:js;toolbar:false;">訪問第1次,?結果：允許訪問????#?第1次，容量剩余2，執行后1 訪問第2次,?結果：允許訪問????#?第2次，容量剩余1，執行后0 訪問第3次,?結果：允許訪問????#?第3次，由于過了2s,?漏斗流水剩余1個空間，所以容量剩余1，執行后0 訪問第4次,?結果：限制訪問????#?第4次，過了1s,?剩余空間小于1，?容量剩余0 訪問第5次,?結果：允許訪問????#?第5次，由于過了2s,?漏斗流水剩余1個空間，所以容量剩余1，執行后0 訪問第6次,?結果：限制訪問????#?以此類推... 訪問第7次,?結果：允許訪問 訪問第8次,?結果：限制訪問 訪問第9次,?結果：允許訪問 訪問第10次,?結果：限制訪問

>?cl.throttle?key:xxx?15?30?60?1

>?cl.throttle?laoqian:reply?15?30?60 1)?(integer)?0???#?0?表示允許，1表示拒絕 2)?(integer)?15??#?漏斗容量capacity 3)?(integer)?14??#?漏斗剩余空間left_quota 4)?(integer)?-1??#?如果拒絕了，需要多長時間后再試(漏斗有空間了，單位秒) 5)?(integer)?2???#?多長時間后，漏斗完全空出來(left_quota==capacity，單位秒)