Could you support filter version?

[y-ken]

Hi @moaikids , CC: @okkez
This lossycount is very useful but it still support only output plugin.
I think It might be better to act as filter plugin. How do you think?
cf. http://qiita.com/moaikids/items/f9e41cebcd97a2d76579#lossycount

[y-ken]

I have noticed due to the filter behavior, It might be impossible to aggregate with specific time bucket.

[okkez]

It is possible to implement filter version like https://github.com/fluent-plugins-nursery/fluent-plugin-concat

Pseudo code:

class Fluent::Plugin::LossyCountFilter < Fluent::Plugin::Filter
  Fluent::Plugin.register_plugin("lossy_count", self)
  # ... snip
  def start
    super
    timer_create(:lossy_count, @interval) do
      # flush counter and emit new record against arbitrary label if needed
    end
  end

  def filter(tag, time, record)
    # push records to internal buffer to count up
    record # do not modify this record
  end
end