#238: PFADD/PFCOUNT implementation

[lucifercr07]

• Adding support for PFADD/PFCOUNT command implementation.
• Hyperloglog implementation library used: axiomhq/hyperloglog
  • Other libraries were analysed like clarkduvall/hyperloglog and datadog/hyperloglog but these are very old and don't seem to be maintained.
• Current implementation only supports Sparse representation and doesn't switch to Dense once threshold is reached as done by Redis. Also it doesn't do caching as part of PFCOUNT.
• TODO In follow up PR when implementing PFMERGE, PFDEBUG etc.:
  • Look into caching implementation if required for PFCOUNT.
  • Benchmark tests for current implementation.
  • Benchmark testing for Sparse and Dense representations.
  • Analyse feasibility of switch between Sparse and Dense representations based on benchmark testing.

[lucifercr07]

@JyotinderSingh / @soumya-codes please review once. Few considerations have listed as part of description here.

[JyotinderSingh]

Could you resolve the conflicts for this PR?

[lucifercr07]

@JyotinderSingh conflicts resolved. Please review once.

[JyotinderSingh]

Thanks for adding these changes @lucifercr07! The changes look good and well tested, just left one minor command.

[JyotinderSingh]

TODO In follow up PR when implementing PFMERGE, PFDEBUG etc.:

• Look into caching implementation if required for PFCOUNT.
• Benchmark tests for current implementation.
• Benchmark testing for Sparse and Dense representations.
• Analyse feasibility of switch between Sparse and Dense representations based on benchmark testing.

Could you please create Issues for these TODOs to ensure we track them?

[lucifercr07]

TODO In follow up PR when implementing PFMERGE, PFDEBUG etc.:

• Look into caching implementation if required for PFCOUNT.
• Benchmark tests for current implementation.
• Benchmark testing for Sparse and Dense representations.
• Analyse feasibility of switch between Sparse and Dense representations based on benchmark testing.

Could you please create Issues for these TODOs to ensure we track them?

Sure, will create. Will try to look into few of them as as part of PFMERGE, PFDEBUG implementations.

[JyotinderSingh]

Thanks for adding HLL support to Dice @lucifercr07! The changes look good and well tested.
LGTM.