Class: Raindrops::LastDataRecv

Inherits:
Object
  • Object
show all
Defined in:
lib/raindrops/last_data_recv.rb

Overview

This is highly experimental!

A self-contained Rack application for aggregating in the tcpi_last_data_recv field in struct tcp_info defined in /usr/include/linux/tcp.h. This is only useful for Linux 2.6 and later. This primarily supports Unicorn and derived servers, but may also be used with any Ruby web server using the core TCPServer class in Ruby.

Hitting the Rack endpoint configured for this application will return a an ASCII histogram response body with the following headers:

  • X-Count - number of requests received

The following headers are only present if X-Count is greater than one.

  • X-Min - lowest last_data_recv time recorded (in milliseconds)

  • X-Max - highest last_data_recv time recorded (in milliseconds)

  • X-Mean - mean last_data_recv time recorded (rounded, in milliseconds)

  • X-Std-Dev - standard deviation of last_data_recv times

  • X-Outliers-Low - number of low outliers (hopefully many!)

  • X-Outliers-High - number of high outliers (hopefully zero!)

To use with Unicorn and derived servers (preload_app=false):

Put the following in our Unicorn config file (not config.ru):

require "raindrops/last_data_recv"

Then follow the instructions below for config.ru:

To use with any Rack server using TCPServer

Setup a route for Raindrops::LastDataRecv in your Rackup config file (typically config.ru):

require "raindrops"
map "/raindrops/last_data_recv" do
  run Raindrops::LastDataRecv.new
end
map "/" do
  use SomeMiddleware
  use MoreMiddleware
  # ...
  run YourAppHere.new
end

To use with any other Ruby web server that uses TCPServer

Put the following in any piece of Ruby code loaded after the server has bound its TCP listeners:

ObjectSpace.each_object(TCPServer) do |s|
  s.extend Raindrops::Aggregate::LastDataRecv
end

Thread.new do
  Raindrops::Aggregate::LastDataRecv.default_aggregate.master_loop
end

Then follow the above instructions for config.ru

Constant Summary collapse

AGGREGATE_THREAD = 
Thread.new { agg.master_loop }

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ LastDataRecv

:startdoc



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# File 'lib/raindrops/last_data_recv.rb', line 75

def initialize(opts = {})
  if defined?(Unicorn::HttpServer::LISTENERS)
    Raindrops::Aggregate::LastDataRecv.cornify!
  end
  @aggregate =
    opts[:aggregate] || Raindrops::Aggregate::LastDataRecv.default_aggregate
end

Instance Method Details

#call(_) ⇒ Object 



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# File 'lib/raindrops/last_data_recv.rb', line 83

def call(_)
  a = @aggregate
  count = a.count
  headers = {
    "Content-Type" => "text/plain",
    "X-Count" => count.to_s,
  }
  if count > 1
    headers["X-Min"] = a.min.to_s
    headers["X-Max"] = a.max.to_s
    headers["X-Mean"] = a.mean.round.to_s
    headers["X-Std-Dev"] = a.std_dev.round.to_s
    headers["X-Outliers-Low"] = a.outliers_low.to_s
    headers["X-Outliers-High"] = a.outliers_high.to_s
  end
  body = a.to_s
  headers["Content-Length"] = body.size.to_s
  [ 200, headers, [ body ] ]
end