Just in time RailsIsrael

Talking about time zones in Ruby and Rails and working through a case study in time zones

Transcript

1. Just in Time A case study in time zones Elle Meredith @aemeredith Just in time
2. Just in time
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6. Today — Touch on time related libraries — Set up Rails to work with user's time zone — Play with Time in Rails — Introduce a feature and work through it Just in time
7. Time DateTime Just in time
8. TZInfo Ruby timezone library, which provides daylight savings aware transformations between times in different timezones. Just in time
9. > TZInfo::Timezone.all.count => 582 Just in time
10. > TZInfo::Timezone.all.count => 582 > TZInfo::Country.get("IL").zone_identifiers => ["Asia/Jerusalem"] Just in time
11. > TZInfo::Timezone.all.count => 582 > TZInfo::Country.get("IL").zone_identifiers => ["Asia/Jerusalem"] > TZInfo::Country.get("AU").zone_identifiers => ["Australia/Lord_Howe", "Antarctica/Macquarie", "Australia/Hobart", ... Just in time
12. > TZInfo::Timezone.all.count => 582 > TZInfo::Country.get("IL").zone_identifiers => ["Asia/Jerusalem"] > TZInfo::Country.get("AU").zone_identifiers => ["Australia/Lord_Howe", "Antarctica/Macquarie", "Australia/Hobart", ... > TZInfo::Country.get("US").zone_identifiers.count => 29 Just in time
13. ActiveSupport ::TimeZone Just in time
14. Limit the set of zones provided by TZInfo to a meaningful subset of 146 zones Just in time
15. Friendlier display "America/New_York" => "Eastern Time (US & Canada)" "Asia/Jerusalem" => Jerusalem Just in time
16. ActiveSupport ::TimeWithZone Just in time
17. $ rake time:zones:all * UTC -11:00 * American Samoa International Date Line West Midway Island Samoa * UTC -10:00 * Hawaii * UTC -09:00 * Alaska ... Just in time
18. Checking current time zone # in console > Time.zone => #<ActiveSupport::TimeZone:0x007fbf46947b38 @current_period=#<TZInfo::TimezonePeriod: nil,nil,#<TZInfo::TimezoneOffset: 0,0,UTC>>>, @name="UTC", @tzinfo=#<TZInfo::TimezoneProxy: Etc/UTC>, @utc_offset=nil> Just in time
19. Setting a custom time zone # in console > Time.zone = "Perth" Just in time
20. Setting a custom time zone # in console > Time.zone = "Perth" # in config/application.rb config.time_zone = "Perth" Just in time
21. Setting a custom time zone # in console > Time.zone = "Perth" # in config/application.rb config.time_zone = "Perth" # ^ the default is "utc" Just in time
22. Stick with UTC Just in time
23. Custom user time zone create_table :users do |t| t.string :time_zone, default: "UTC" ... end Just in time
24. No enums Yes strings Just in time
25. Custom user time zone: forms # Simple Form <%= f.input :time_zone %> Just in time
26. Custom user time zone: setting # app/controllers/application_controller.rb around_action :set_time_zone, if: :current_user private def set_time_zone(&block) Time.use_zone(current_user.time_zone, &block) end Just in time
27. Custom user time zone: displaying <%= time.in_time_zone(curent_user.time_zone) %> Just in time
28. ISO8601 and APIs > time = Time.now.utc.iso8601 => "2015-07-04T21:53:23Z" Just in time
29. ISO8601 and APIs > time = Time.now.utc.iso8601 => "2015-07-04T21:53:23Z" > Time.iso8601(time) => 2015-07-04 21:53:23 UTC Just in time
30. 3 different times — System time — Application time — Database time Just in time
31. > Time.zone.name => "UTC" Just in time
32. > Time.zone.name => "UTC" > Time.now => 2015-07-04 17:53:23 -0400 Just in time
33. > Time.zone.name => "UTC" > Time.now => 2015-07-04 17:53:23 -0400 > Time.zone = "Fiji" => "Fiji" Just in time
34. > Time.zone.name => "UTC" > Time.now => 2015-07-04 17:53:23 -0400 > Time.zone = "Fiji" => "Fiji" > Time.zone.name => "Fiji" Just in time
35. > Time.zone.name => "UTC" > Time.now => 2015-07-04 17:53:23 -0400 > Time.zone = "Fiji" => "Fiji" > Time.zone.name => "Fiji" > Time.now => 2015-07-04 17:53:37 -0400 Just in time
36. > Time.zone.name => "UTC" > Time.now => 2015-07-04 17:53:23 -0400 > Time.zone = "Fiji" => "Fiji" > Time.zone.name => "Fiji" > Time.now => 2015-07-04 17:53:37 -0400 > Time.zone.now Just in time
37. > Time.zone.name => "UTC" > Time.now => 2015-07-04 17:53:23 -0400 > Time.zone = "Fiji" => "Fiji" > Time.zone.name => "Fiji" > Time.now => 2015-07-04 17:53:37 -0400 > Time.zone.now => Sun, 05 Jul 2015 09:53:42 FJT +12:00 Just in time
38. > Time.zone = "Fiji" => "Fiji" > Time.zone.name => "Fiji" > Time.now => 2015-07-04 17:53:37 -0400 > Time.zone.now => Sun, 05 Jul 2015 09:53:42 FJT +12:00 > Time.current Just in time
39. > Time.zone.name => "Fiji" > Time.now => 2015-07-04 17:53:37 -0400 > Time.zone.now => Sun, 05 Jul 2015 09:53:42 FJT +12:00 > Time.current => Sun, 05 Jul 2015 09:54:17 FJT +12:00 Just in time
40. > Time.zone = "Fiji" => "Fiji" > Time.zone.name => "Fiji" > Time.now => 2015-07-04 17:53:37 -0400 > Time.zone.now => Sun, 05 Jul 2015 09:53:42 FJT +12:00 > Time.current => Sun, 05 Jul 2015 09:54:17 FJT +12:00 > Time.now.in_time_zone => Sun, 05 Jul 2015 09:56:57 FJT +12:00 Just in time
41. > Time.zone.name => "Fiji" Just in time
42. > Time.zone.name => "Fiji" > Date.today => Sat, 04 Jul 2015 Just in time
43. > Time.zone.name => "Fiji" > Date.today => Sat, 04 Jul 2015 > Time.zone.today => Sun, 05 Jul 2015 Just in time
44. > Time.zone.name => "Fiji" > Date.today => Sat, 04 Jul 2015 > Time.zone.today => Sun, 05 Jul 2015 > Time.zone.tomorrow => Mon, 06 Jul 2015 Just in time
45. > Time.zone.name => "Fiji" > Date.today => Sat, 04 Jul 2015 > Time.zone.today => Sun, 05 Jul 2015 > Time.zone.tomorrow => Mon, 06 Jul 2015 > 1.day.from_now => Mon, 06 Jul 2015 10:00:56 FJT +12:00 Just in time
46. Time zone related querying Post.where("published_at > ?", Time.current) # SELECT "posts".* FROM "posts" # WHERE (published_at > # '2015-07-04 17:45:01.452465') Just in time
47. DON'T * Time.now DO * Time.current * 2.hours.ago Just in time
48. DON'T * Date.today * Date.today.to_time DO * Time.zone.today * 1.day.from_now Just in time
49. DON'T * Time.parse("2015-07-04 17:05:37") * Time.strptime(string, "%Y-%m-%dT%H:%M:%S%z") DO * Time.zone.parse("2015-07-04 17:05:37") * Time.strptime( string, "%Y-%m-%dT%H:%M:%S%z" ).in_time_zone Just in time
50. Testing time zones ActiveSupport::Testing::TimeHelpers travel_to 1.day do # do something tomorrow end travel_back Just in time
51. Testing time zones: gems # Timecop Timecop.freeze new_time Timecop.travel new_time Timecop.return Time.use_zone("Sydney") do … end # Delorean Delorean.time_travel_to("1 month ago") do … end Delorean.back_to_the_present # Zonebie Zonebie.set_random_timezone Just in time
52. Recent Project Just in time
53. First go — Test suites that needed to run daily or weekly, — at a set time (1AM or 2AM), — and use ResqueScheduler to set the schedule to run the background workers. Just in time
54. ScheduleRule Just in time
55. ResqueScheduler # config/resque_schedule.yml weekly_test: cron: "0 1 * * 0" class: ScheduledWeeklyRunsWorker args: description: 'Run test suites weekly' daily_test: cron: "0 2 * * *" class: ScheduledDailyRunsWorker args: description: 'Run test suites daily' Just in time
56. Cron Syntax * * * * * command to execute ┬ ┬ ┬ ┬ ┬ │ │ │ │ │ │ │ │ │ │ │ │ │ │ └───── day of week (0 - 7) from Sunday │ │ │ └────────── month (1 - 12) │ │ └─────────────── day of month (1 - 31) │ └──────────────────── hour (0 - 23) └───────────────────────── min (0 - 59) Just in time
57. So what was the problem? The scheduled tests were running at 2AM AEST regardless of the user’s time zone. Just in time
58. Second go — Test runs according to user's settings, at a specific week day, hour, and time zone. — ResqueScheduler to run hourly and look for test suites that are due to run. — The ResqueScheduler to look for test runs where the background job failed and thus due to be run as well. Just in time
59. ScheduleRule.rb every: string, wday: integer, hour: integer, time_zone: string, last_scheduled_run_at: timestamp, suite: references, ... Just in time
60. Still second go # lib/extensions.rb module ActiveSupport class TimeZone def self.current_zones(hour) all.select { |zone| t = Time.current.in_time_zone(zone) t.hour == hour }.map(&:tzinfo).map(&:name) end end end Just in time
61. Still second go # app/models/schedule_rule.rb class ScheduleRule < ActiveRecord::Base def self.find_rules(options={}) hour = options[:hour] where(zone: ActiveSupport::TimeZone.current_zones(hour)). where(options) end def self.suites_to_run(time_ago=Time.current, options={}) find_rules(options). older_than(time_ago). map(&:suite) end end Just in time
62. Still second go # app/workers/scheduled_runs_worker.rb class ScheduledRunsWorker def self.perform ScheduleRule. run_scheduled. daily. suites_to_run(yesterday, {hour: Time.now.utc.hour}) end end Just in time
63. Can we do better? Just in time
64. Meet hour in utc Just in time
65. Third go — Remove the .current_zones method. — Introduce the :hour_in_utc column in ScheduleRule class. Just in time
66. Third go class AddHourInUtc < ActiveRecord::Migration def change add_column :schedule_rules, :hour_in_utc, :integer end end Just in time
67. Still third go # app/models/schedule_rule.rb class ScheduleRule < ActiveRecord::Base before_save :set_hour_in_utc private def set_hour_in_utc self.hour_in_utc = ActiveSupport::TimeZone[zone]. parse("#{hour}:00:00"). utc. hour end end Just in time
68. Still third go # app/models/schedule_rule.rb class ScheduleRule < ActiveRecord::Base def self.suites_to_run(time_ago=Time.current, options={}) where(options). older_than(time_ago). map(&:suite) end end Just in time
69. Worker didn't change # app/workers/scheduled_runs_worker.rb class ScheduledRunsWorker def self.perform ScheduleRule. run_scheduled. daily. suites_to_run(yesterday, {hour: Time.now.utc.hour}) end end Just in time
70. Previously # app/models/schedule_rule.rb class ScheduleRule < ActiveRecord::Base def self.find_rules(options={}) hour = options[:hour] where(zone: ActiveSupport::TimeZone.current_zones(hour)). where(options) end def self.suites_to_run(time_ago=Time.current, options={}) find_rules(options). older_than(time_ago). map(&:suite) end end Just in time
71. Currently class ScheduleRule < ActiveRecord::Base def self.suites_to_run(time_ago=Time.current, options={}) where(options). older_than(time_ago). map(&:suite) end end Just in time
72. Always work with UTC Just in time
73. A couple more takeaways — Use Time.current or Time.zone.today. — Freeze the time in your tests, preferably by using a block. Just in time
74. Almost done — robots.thoughtbot.com — speakerdeck.com/aemeredith — @aemeredith — https://www.youtube.com/watch?v=-5wpm-gesOY Just in time
75. Thanks! Just in time