Rewriting Critical Parts of Your Application Using... @jesseplusplus - GitHub Science!

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a rewrite ? ! ? !

history

! First, there was collaboration

! Then, there was organization

! ! separate ways of granting permissions living side-by-side " tons of bugs and edge cases around transitional states # performance degradation

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!

rewrite !

! Interface

! user.can? :read, repository repository.grant user, :write repository.revoke user

! | :read, :write, :admin |

! +------+ | User |-------------- +------+ +------+ | Team |-------------- +------+ +------------+ | Repository |-------- +------------+

! +------+ | User |---------------- +------+ +------+ 1 | Team |--------+------- +------+ | | +------------+ v | Repository |---------- +------------+

! +------+ 2 | User |-----------+---- +------+ | | +------+ 1 v | Team |--------+------- +------+ | | +------------+ v | Repository |---------- +------------+

! +------+ 2 3 | User |-----------+--+- +------+ | . | . +------+ 1 v . | Team |--------+-----.- +------+ | . | . +------------+ v v | Repository |---------- +------------+

! performance #

! existing API easy to compare class Repository # Is the given user allowed # to pull this repository? def pullable_by?(user) # is the user a collaborator # or a member of a team with access # or part of some other edge case? . . . end end

! lists of repositories, pull requests, teams, etc. # Find all repositories which this organization # controls the access to. ! def organization.controlled_repositories . . . end

! lists of repositories, pull requests, teams, etc. # Find all pull requests to which this user # has access. Access to PRs follow the user’s # access rights to the PR’s repository. ! def user.accessible_pull_requests . . . end

! SELECT r.id FROM r, (( SELECT r.id as r_ids, 2 as perms from r WHERE r.owner_id = 99999 AND (r.x = 0) ) UNION ALL ( SELECT r.id as r_ids, 1 as perms from r INNER JOIN p ON r.id = p.r_id WHERE p.u_id = 99999 AND (r.x = 0) ) UNION ALL ( SELECT r.id as r_ids, 2 as perms from r INNER JOIN t ON r.o_id = t.o_id INNER JOIN t_m ON t.id = t_m.t_id WHERE t.name = 'X' AND t_m.u_id = 99999 AND (r.x = 0) ) UNION ALL ( SELECT r.id as r_ids, GROUP_CONCAT(distinct t.p) as perms from r INNER JOIN t_m r_t ON r.id = r_t.r_id INNER JOIN t ON r_t.t_id = t.id INNER JOIN t_m u_t ON t.id = u_t.t_id WHERE u_t.u_id = 99999 AND t.name != 'X' AND t.p in (2, 1, 0) AND (r.x = 0) GROUP BY r.id ) UNION ALL ( SELECT r.id as r_ids, 0 as perms from r JOIN u ON r.plan_owner_id = u.id JOIN t ON t.o_id = u.id JOIN t_m ON t.id = t_m.t_id WHERE u.type = 'XX' AND t.name = 'X' AND t_m.u_id = 99999 AND (r.x = 0) AND r.parent_id IS NOT NULL )) AS unioned WHERE r.id = r_ids;

! test coverage : less than ideal

rewrite …and refactor

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! class Repository def pullable_by?(user) science "ability.repository.pullable-by" do |e| e.context :user => (user.id if user), :repo => id ! e.control { pullable_by_legacy?(user) } e.candidate { pullable_by_abs?(user) } end end ! def pullable_by_abs?(user) user.can? :read, self end ! def pullable_by_legacy?(user) # original code for pullable_by? # collaborators || team || special case end end

! class Repository def pullable_by?(user) science "ability.repository.pullable-by" do |e| e.context :user => (user.id if user), :repo => id ! e.control { pullable_by_legacy?(user) } e.candidate { pullable_by_abs?(user) } end end ! def pullable_by_abs?(user) user.can? :read, self end ! def pullable_by_legacy?(user) # original code for pullable_by? # collaborators || team || special case end end

! class Repository def pullable_by?(user) science "ability.repository.pullable-by" do |e| e.context :user => (user.id if user), :repo => id ! e.control { pullable_by_legacy?(user) } e.candidate { pullable_by_abs?(user) } end end ! def pullable_by_abs?(user) user.can? :read, self end ! def pullable_by_legacy?(user) # original code for pullable_by? # collaborators || team || special case end end

! class Repository def pullable_by?(user) science "ability.repository.pullable-by" do |e| e.context :user => (user.id if user), :repo => id ! e.control { pullable_by_legacy?(user) } e.candidate { pullable_by_abs?(user) } end end ! def pullable_by_abs?(user) user.can? :read, self end ! def pullable_by_legacy?(user) # original code for pullable_by? # collaborators || team || special case end end

! class Repository def pullable_by?(user) science "ability.repository.pullable-by" do |e| e.context :user => (user.id if user), :repo => id ! e.control { pullable_by_legacy?(user) } e.candidate { pullable_by_abs?(user) } end end ! def pullable_by_abs?(user) user.can? :read, self end ! def pullable_by_legacy?(user) # original code for pullable_by? # collaborators || team || special case end end

! class Repository def pullable_by?(user) science "ability.repository.pullable-by" do |e| e.context :user => (user.id if user), :repo => id ! e.control { pullable_by_legacy?(user) } e.candidate { pullable_by_abs?(user) } end end ! def pullable_by_abs?(user) user.can? :read, self end ! def pullable_by_legacy?(user) # original code for pullable_by? # collaborators || team || special case end end

! class Science::Experiment def publish(event, payload) instrument "science.#{event}", payload end end

subscribe /^science\./ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.total" timing "#{experiment}.control", payload[:control][:duration] timing "#{experiment}.candidate", payload[:candidate][:duration] end ! subscribe /^science\.mismatch/ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.wrong" Redis.lpush "#{experiment}.mismatch", payload.to_json end

subscribe /^science\./ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.total" timing "#{experiment}.control", payload[:control][:duration] timing "#{experiment}.candidate", payload[:candidate][:duration] end ! subscribe /^science\.mismatch/ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.wrong" Redis.lpush "#{experiment}.mismatch", payload.to_json end

subscribe /^science\./ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.total" timing "#{experiment}.control", payload[:control][:duration] timing "#{experiment}.candidate", payload[:candidate][:duration] end ! subscribe /^science\.mismatch/ do |name, . . ., payload| name = payload[:experiment] experiment = "science.#{name}" ! increment "#{experiment}.wrong" Redis.lpush "#{experiment}.mismatch", payload.to_json end

subscribe /^science\./ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.total" timing "#{experiment}.control", payload[:control][:duration] timing "#{experiment}.candidate", payload[:candidate][:duration] end ! subscribe /^science\.mismatch/ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.wrong" Redis.lpush "#{experiment}.mismatch", payload.to_json end

subscribe /^science\./ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.total" timing "#{experiment}.control", payload[:control][:duration] timing "#{experiment}.candidate", payload[:candidate][:duration] end ! subscribe /^science\.mismatch/ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.wrong" Redis.lpush "#{experiment}.mismatch", payload.to_json end

subscribe /^science\./ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.total" timing "#{experiment}.control", payload[:control][:duration] timing "#{experiment}.candidate", payload[:candidate][:duration] end ! subscribe /^science\.mismatch/ do |name, . . ., payload| experiment = "science.#{payload[:experiment]}" ! increment "#{experiment}.wrong" Redis.lpush "#{experiment}.mismatch", payload.to_json end

! class Experiment < Science::Experiment def enabled? self.class.enabled? && rand(100) < percentage end end

! class Experiment < Science::Experiment def enabled? self.class.enabled? && rand(100) < percentage end end

! class Experiment < Science::Experiment def enabled? self.class.enabled? && rand(100) < percentage end end

! science all the things

! $ examining the data

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!

!

! analyzing mismatches

! class Analysis def read Redis.rpop "science.#{experiment_name}.mismatch" end def count Redis.llen "science.#{experiment_name}.mismatch" end end

! irb(main):001> analysis = Analysis.new('ability.repository.pullable-by') => #> ! irb(main):002> analysis.count => 3283 ! irb(main):003> result = analysis.fetch => {"from"=>"GitHub::Jobs::ProcessEvent", "experiment"=>"ability.repository.pullable-by", "user"=>XXXXXXX, “repo"=>XXXXXXX, "timestamp"=>"2014-05-28T18:53:16-07:00", "candidate"=>{"duration"=>0.41368900000000003, "exception"=>nil, "value"=>false}, "control"=>{"duration"=>1.141963, "exception"=>nil, "value"=>true}, "first"=>"control"} !

! irb(main):001> analysis = Analysis.new('ability.repository.pullable-by') => #> ! irb(main):002> analysis.count => 3283 ! irb(main):003> result = analysis.fetch => {"from"=>"GitHub::Jobs::ProcessEvent", "experiment"=>"ability.repository.pullable-by", "user"=>XXXXXXX, “repo"=>XXXXXXX, "timestamp"=>"2014-05-28T18:53:16-07:00", "candidate"=>{"duration"=>0.41368900000000003, "exception"=>nil, "value"=>false}, "control"=>{"duration"=>1.141963, "exception"=>nil, "value"=>true}, "first"=>"control"} !

! irb(main):001> analysis = Analysis.new('ability.repository.pullable-by') => #> ! irb(main):002> analysis.count => 3283 ! irb(main):003> result = analysis.fetch => {"from"=>"GitHub::Jobs::ProcessEvent", "experiment"=>"ability.repository.pullable-by", "user"=>XXXXXXX, “repo"=>XXXXXXX, "timestamp"=>"2014-05-28T18:53:16-07:00", "candidate"=>{"duration"=>0.41368900000000003, "exception"=>nil, "value"=>false}, "control"=>{"duration"=>1.141963, "exception"=>nil, "value"=>true}, "first"=>"control"} !

! irb(main):001> analysis = Analysis.new('ability.repository.pullable-by') => #> ! irb(main):002> analysis.count => 3283 ! irb(main):003> result = analysis.fetch => {"from"=>"GitHub::Jobs::ProcessEvent", "experiment"=>"ability.repository.pullable-by", "user"=>XXXXXXX, “repo"=>XXXXXXX, "timestamp"=>"2014-05-28T18:53:16-07:00", "candidate"=>{"duration"=>0.41368900000000003, "exception"=>nil, "value"=>false}, "control"=>{"duration"=>1.141963, "exception"=>nil, "value"=>true}, "first"=>"control"} !

! irb(main):001> analysis = Analysis.new('ability.repository.pullable-by') => #> ! irb(main):002> analysis.count => 3283 ! irb(main):003> result = analysis.fetch => {"from"=>"GitHub::Jobs::ProcessEvent", "experiment"=>"ability.repository.pullable-by", "user"=>XXXXXXX, “repo"=>XXXXXXX, "timestamp"=>"2014-05-28T18:53:16-07:00", "candidate"=>{"duration"=>0.41368900000000003, "exception"=>nil, "value"=>false}, "control"=>{"duration"=>1.141963, "exception"=>nil, "value"=>true}, "first"=>"control"} !

! " % &'

! % data quality

! &'

… and repair rewrite …and refactor …and $ $ … and #

!

soon . . .

! http://github.com/ github/dat-science ( dat-science ( dat-analysis http://github.com/github/dat-analysis

! Muchas Gracias!