/utils/latency/latency.rb

#!/usr/bin/env ruby
# coding: utf-8

require "em-ucengine"
require "./lib/score"

# The purpose of this script is to mesure two things:
#
#  - The time an event take to be received via the streaming API
#  - The time an event take to be published
#
# To do so, we run multiple batches which sent events.
#
# The COUNTER_LIMIT and EVENTS_LIMIT constants configure the number of batch to
# run. For instance, if COUNTER_LIMIT equals 5 and EVENTS_LIMIT equals 8 we
# got the following:
#
# First 1 event is sent every 1 second 5 times
# Then 2 events is sent every 1 second 5 times
# Then 4 events is sent every 1 second 5 times
# Then 8 events is sent every 1 second 5 times
# Here we stop because we reached EVENTS_LIMIT

COUNTER_LIMIT = 5 # Number of runs per batch
EVENTS_LIMIT = 100 # Maximum number of event sent per batch

$test_number = 0

def latency(filters={})
    filters[:types] ||= 'test.latency'
    filters[:event_generator] ||= Proc.new do |cpt|
        'test.latency'
    end
    filters[:parent] ||= false

    EventMachine::UCEngine.run('localhost', 5280) do |uce|
        broadcast_scores = Score.new
        publishing_scores = Score.new
        parent_event = nil

        uce.connect("participant", "pwd") do |error, session|
            session.publish("parent_event", "demo") do |err, event_id|
                parent_event = (filters[:parent]) ? event_id : nil
                params = {
                    :type => filters[:types],
                    :parent => parent_event,
                }

                subcription = session.subscribe("demo", params) do |err, events|
                    events.each do |event|
                        received = Time.new
                        batch = event['metadata']['batch']
                        score = (received.to_f * 1000000).to_i - event['metadata']['timer']
                        broadcast_scores[batch] << score
                    end
                end

                nb_events = 1
                repeat = 0
                timer = EM::PeriodicTimer.new(1) do
                    nb_events.times do |i|
                        sent = Time.new
                        event =filters[:event_generator].call(repeat + i, parent_event)
                        metadata = {
                            :timer => (sent.to_f * 1000000).to_i,
                            :batch => nb_events
                        }.merge(event[:metadata] || {})

                        session.publish(event[:type], "demo", metadata, event[:parent]) do |err, event_id|
                            score = ((Time.new - sent) * 1000000).to_i
                            publishing_scores[nb_events] << score
                            last_event = event_id
                        end

                        print "."
                    end

                    # We reached the event limit, so we stop
                    if nb_events >= EVENTS_LIMIT
                        # Waiting for the last events
                        EM::add_timer 2 do
                            $test_number += 1
                            broadcast_scores.sort!
                            File.open("scores#{$test_number}.csv",'w') do |f|
                                f.write broadcast_scores.to_all_csv
                            end
                            broadcast_scores.each do |batch, scores|
                                p "90% of #{batch} events travel in less than #{broadcast_scores.get_9_decile(batch)} µs, min: #{scores[0]} µs, max: #{scores[-1]} µs"
                            end

                            puts
                            publishing_scores.sort!
                            File.open("publishing#{$test_number}.csv",'w') do |f|
                                f.write publishing_scores.to_csv
                            end

                            #publishing_scores.values.map(&:sort).each_with_index do |score, n|
                            #    p "90% of #{n*10} events were published in less than #{score[score.length * 0.9]} µs, min: #{score[0]} µs, max: #{score[-1]} µs"
                            timer.cancel
                            subcription.cancel { EM.stop }

                            #end

                        end
                    end

                    repeat += 1

                    # We reached the end of a batch
                    if repeat == COUNTER_LIMIT
                        nb_events += 10
                        repeat = 0
                        puts
                    end

                end
            end
        end
    end
end

#latency()

## Test with a single type
latency({
    :types => 'test.latency',
    :parent => false,
    :event_generator => Proc.new do |cpt|
        { :type => (cpt % 2 == 1 ) ? 'test.latency' : 'test.doomed' }
    end
})

## Test with two types
latency({
    :types => 'test.latency,test.again',
    :event_generator => Proc.new do |cpt, last_event|
        { :type =>
            ['test.latency', 'test.doomed', 'test.again'][cpt % 3]
        }
    end
})

## Test with parent
latency({
    :types => 'test.latency',
    :event_generator => Proc.new do |cpt, parent|
        { :type   => 'test.latency',
          :parent => ((cpt %2) == 0) ? parent : nil
        }
    end
})