Benchmarking and tuning the performance of Cache#read_multi with refreshing

refresh_bench.rb

require 'benchmark/ips'
require 'readthis'

cache = Readthis::Cache.new(namespace: 'rd', expires_in: 60)
range = ('a'..'z').to_a

range.each { |key| cache.write(key, key) }

Benchmark.ips do |x|
  x.report 'read_multi:standard' do
    cache.read_multi(*range.sample(15))
  end

  x.report 'read_multi:refresh' do
    cache.read_multi(*range.sample(15), refresh: true)
  end

  x.report 'read_multi:lua' do
    cache.lua_read_multi(*range.sample(15), refresh: true)
  end

  x.compare!
end

results.txt

Press ENTER or type command to continue
Calculating -------------------------------------
 read_multi:standard   452.000  i/100ms
  read_multi:refresh   139.000  i/100ms
      read_multi:lua   456.000  i/100ms
-------------------------------------------------
 read_multi:standard      4.579k (± 3.4%) i/s -     23.052k
  read_multi:refresh      1.410k (± 1.8%) i/s -      7.089k
      read_multi:lua      4.571k (± 4.6%) i/s -     22.800k

Comparison:
 read_multi:standard:     4579.2 i/s
      read_multi:lua:     4571.3 i/s - 1.00x slower
  read_multi:refresh:     1409.7 i/s - 3.25x slower