The document discusses several ways to implement parallel features or versions including: 1. Substitution - Implementing a feature by substituting one codebase for another. For example, substituting a new hypervisor driver implementation. 2. Feature toggles - Implementing features that can be toggled on or off via configuration to gradually roll out changes. 3. Feature versioning - Implementing different versions of a feature or component side by side to support multiple versions simultaneously via an abstraction layer. The document provides examples of each approach including substituting queue backends and implementing different network configuration versions via an abstraction layer. Overall the techniques allow adding new features or versions in parallel to existing codebases.

1. Implementações paralelas
Willian Molinari
a.k.a PotHix

2. WTF

3. 1996!!
John Carmack

4. https://github.com/id-Software

5. #AltDevBlogADay

6. Várias formas de
implementações paralelas

7. 1. Substitution

8. Master

9. Código no branch principal
class VirtualMachine
def name
hypervisor_session.VM.get_name(uuid)
end
.
.
.
end

10. Código código no branch novo
class VirtualMachine
def name
on_hypervisor.VM.get_name(uuid)
end
.
.
.
end

11. Master NewFeature
Feature

12. "Virar a chave"

14. Dá para evitar?

15. 2. Feature Toggle

16. 2. Feature Toggle
Para adição de funcionalidade

17. Martin Fowler
http://martinfowler.com/bliki/FeatureToggle.html

18. Master
Feature1
Merge Release
Feature2
Feature3

19. Martin Fowler
http://martinfowler.com/bliki/FeatureToggle.html

20. Nando Vieira
http://simplesideias.com.br/usando-presenters-no-rails/

21. 2. Feature Toggle
Para várias implementações

22. Fabio Kung
http://fabiokung.com/2010/10/16/dsls-one-interface-multiple-implementations/

23. Qual a idéia?

24. module Resque
class Consumer
class << self
def queue(name)
@queue = name
end
def timeout(seconds=nil)
@lock_timeout = seconds unless seconds
@lock_timeout || 1.hour
end
def exclusive(param)
@exclusive = param
self.extend(Resque::Plugins::LockTimeout) if exclusive?
@lock_timeout ||= 1.hour
end
def publish(message={})
Resque.enqueue(self, message)
end
...
end
end
end

25. module ActiveMQ
class Consumer
class << self
attr_reader :queue_name, :queued_process, :headers, :timeout_value
def queue(name)
@queue_name = "/queue/#{name}"
end
def timeout(seconds)
@timeout_value = seconds
end
def exclusive(param)
@exclusive = param
end
def publish(message = {})
client = Stomp::Client.new(NephelaeConfig[:broker].merge(:max_reconnect_attempts => 1))
client.publish(queue_name, message.to_yaml, {
:persistent => true, :suppress_content_length => true
})
end
...
end
end
end

26. require 'xmpp4r'
module XMPP
class Consumer
class << self
attr_reader :queue_name, :queued_process, :timeout_value
def queue(name)
@queue_name = "#{name}@localhost"
end
def timeout(seconds)
@timeout_value = seconds
end
def exclusive(param)
@exclusive = param
end
def publish(message={})
publisher_client.send(Jabber::Message.new(queue_name, message.to_yaml))
end
...
end
end
end

27. app/consumers/consumer.rb
Consumer = ActiveMQ::Consumer

28. app/consumers/consumer.rb
Consumer = XMPP::Consumer

29. app/consumers/consumer.rb
Consumer = Resque::Consumer

30. Injeção de dependencia
MyQueue.new(Resque::Consumer)

31. Por configuração

32. 3. Feature versioning

33. Manager
Ver1 Ver2

34. module Network
class Ver1
def insert_filter_rule(filter_rule)
filter_rule.firewalls.in_parallel do |firewall|
ssh_executor = SSHExecutor.new(firewall.ip_address, 'sservice')
result = ssh_executor.exec(
:insert_filter_firewall_rules, :rule => filter_rule,
:internal_address => filter_rule.ip_pair.private_ip,
:firewall => firewall
)
raise "Insertion failed: #{result[:out]}" if result[:status] != 0
end
filter_rule.update_attribute(:status, :done)
end
def insert_dhcp_entry(vm)
vm.zone.dhcps.in_parallel do |dhcp_server|
result = dhcp_server.synchronize
raise "DHCP failed: #{result[:out]}" if result[:status] != 0
end
end
end
end

35. Manager
Ver1 Ver2

36. module Network
class Ver2
def insert_filter_rule(filter_rule)
quantum = Openstack::QuantumClient::L2l3.new(NephelaeConfig[:quantum])
quantum_response = quantum.filter_rule.create(
filter_rule.filter_address,
filter_rule.ip_pair.public_ip.to_s,
filter_rule.filter_port,
filter_rule.filter_protocol
)
filter_rule.update_attribute(:quantum_uuid, quantum_response["filter_rule"]["id"])
end
def insert_dhcp_entry(vm)
quantum = Openstack::QuantumClient::L2l3.new(NephelaeConfig[:quantum])
quantum_response = quantum.dhcp_entry.create(vm.public_ip.to_s, vm.mac, vm.name)
end
end

37. Manager
"1.0" "2.0"
Ver1 Ver2

38. module Network
module Manager
extend self
def for(versioning_object)
versioning_object.version == "2.0" ? Network::Ver2.new : Network::Ver1.new
end
end
end

39. module Network
module Manager
extend self
def for(versioning_object)
versioning_object.version.constantize.new
end
end
end
Network::Manager.for(pool).insert_filter_rule(virtual_machine)

40. Várias formas de
atacar o problema
r bu llet
os ilve
N
Resumindo
Su bene fício
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sida
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41. Perguntas?