Redis performance

[brasic]

We are using this gem at ShippingEasy to manage rate limiting API endpoints. It works great, but while reviewing the source I found a few areas where its performance could be improved:

• evalsha should be preferred to eval, since it reduces script compilation and network overhead (490b7be28138cbf207828b324646648263e68601 and 6474c7aace4a411f7e5159a1a3e490fbb4b1feb9)
• independent adjacent calls to redis should be pipelined to avoid multiple round trips (035d6ed40a52a38aa74bb18c011ee85012ee4a2b)
• A combination of SETNX and PEXPIRE is equivalent to and can be replaced with a single SET call with NX and PX options (722c516cdc01b067a3ba4083be0e1207fbb0587f). As a beneficial side effect, not only does this perform better but it turns set_if_not_exists_with_ttl into an atomic operation.

[tobischo]

Released v1.0.4 https://rubygems.org/gems/gcra/versions/1.0.4 with your changes

Thank you for your contribution :-)

[brasic]

Thanks for the fast review and this very useful gem!