cached_weth_price_repository.rb

def weth_price
    weth_price = @redis.get(WETH_PRICE_REDIS_KEY)
    if weth_price.blank?
      weth_price = update_cache_for_weth_price_from_db
    end

    weth_price
  end

  def update_cache_for_weth_price_from_db
    weth = @coin_repository.weth
    weth_price_usd = weth.price_usd

    @redis.setex(WETH_PRICE_REDIS_KEY,
                 WETH_PRICE_REDIS_TTL,
                 weth_price_usd)

    weth_price_usd
  end