bad cache

bad_cache.rb

thing1 = { data: 'data1', size: 10 }
thing2 = { data: 'data2', size: 20 }
thing3 = { data: 'data3', size: 5 }
require 'time'
require 'ap'
class Cache
  def initialize(size:)
    @size = size
    @things = []
    @locations = {} # key: @things  pointer
    @cache_utilization = 0
  end

  def put(key, thing)
    if @locations[key]
      to_drop = @locations[key]
      @cache_utilization -= to_drop[:size]
      @locations.delete(to_drop[:key])
      @things.delete_at(@things.find_index { |data| data[:key] == key }) # :(
    end

    while @cache_utilization + thing[:size] > @size
      dropped_thing = @things.shift
      @cache_utilization -= dropped_thing[:size]
      @locations.delete(dropped_thing[:key])
    end

    @locations[key] = thing
    @things << thing.merge(key: key)
    @cache_utilization += thing[:size]
  end

  def get(key)
    value = @locations[key]
    return unless value
    idx = @things.find_index { |data| data[:key] == key }
    @things.delete_at(idx) # :(
    @things << value
  end
end

c = Cache.new(size: 30)
c.put(:a, thing1)
# ap c.inspect
c.put(:a, { data: 'hi', size: 9 })
p c.inspect
c.put(:b, thing2)
p c.get(:a)
p c.inspect
c.put(:c, thing3) # out of space, thing 1 is dropped
p c.inspect
# p c.get(:a)
# p c.get(:b)
# p c.get(:c)