gistfile1.txt

# Round expiry to encourage HTTP caching.
# 5-minute expiry at 6:03 would round up from 6:08 to 6:10.
module QuantizedExpiry
  def url_for(name, options = {})
    unless options[:expires]
      t = (options.delete(:expires_in) || 5.minutes).to_i
      options[:expires] = t * (2 + (Time.now.to_i / t))
    end
    super
  end
end

AWS::S3::S3Object.extend QuantizedExpiry