[HDFS-15202] boost short circuit cache

[pustota2009]

Improve HDFS-client reading performance. The idea: create few instances ShortCircuit caches instead of one.

[leosunli]

@pustota2009
firstly, you need add UT about SCR optimization in your patch.
secondly, i suggest you to design a strategy which is allocated to a specific ShortCircuitCache. This should improve performance even more.
this jira is only the first step of optimization.

[pustota2009]

@leosunli
Take a look please at this UT - is it ok?
Could you explain about the strategy design? Unfortunately I don't catch what do you mean.