Redis-based token client implementation of cluster flow control

TokenServer为什么不基于Redis时间窗口来实现呢？或者Redis本身就是一个TokenServer呀！
以“应用名_资源名_规则ID_参数值”作为redis的Key，时间窗口长度（durationInSec）为ttl，创建一条redis记录，创建记录通过 set key value ex ttl nx 指令，确保时间窗口内有且仅有一条有效记录。然后，通过incrBy key count指令进行分布式累积，当累积值超过阀值时，触发限流。
此外，还可以利用redis的分布式和抗压的特点，提长TokenServer的性能。
-- For English user
why TokenServer is not based on Redis? or Redis itselt is a good TokenServer!
create a redis key like "namespace_resource_flowId_param", ttl=durationInSec, use cmd "set key value ex ttl nx" to make sure in timeWindow only create on record. then use cmd "incrBy key count"
for accumulation. if count > threshold then fired block Event.

Start by reviewing the existing TokenServer flow-control path and the Redis commands named in the issue: SET with EX/NX and INCRBY. Determine where a Redis-backed client would integrate and how threshold breaches should trigger the block event. Done means the proposed Redis-based cluster flow-control behavior is implemented and verified against the existing TokenServer expectations.

Written by the indexing model from the issue text.