Make ActiveSupport::TimeZone.all independent of previous lookups #31176
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activesupport/test/time_zone_test.rb
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| @@ -8,6 +8,17 @@ | |||
| class TimeZoneTest < ActiveSupport::TestCase | |||
| include TimeZoneTestHelpers | |||
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| def setup | |||
| ActiveSupport::TimeZone.instance_variable_set(:@lazy_zones_map, Concurrent::Map.new) | |||
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This setup is overly coupled to the internal details of the implementation
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Do you have any suggestions for an alternative way to do this? The test I wrote depends on the caches being cleared before making the first call to ActiveSupport::TimeZone.all.
| MAPPING.each_key { |place| self[place] } # load all the zones | ||
| @lazy_zones_map | ||
| end | ||
| @zones_map ||= Hash[MAPPING.keys.map { |place| [place, self[place]] }] |
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This can be written as:
@zones_map ||= MAPPING.transform_values { |tz| self[tz] }There was a problem hiding this comment.
Not quite. It seems important to use the keys of MAPPING to perform lookups using #[] because the argument to #[] ends up on the name attribute of the returned ActiveSupport::TimeZone instance.
> Hash[MAPPING.keys.map { |k| [k, self[k]] }]['UTC'].name
=> "UTC"
> MAPPING.transform_values { |v| self[v] }['UTC'].name
=> "Etc/UTC"If there's a nice way to use Hash#transform_values in a way that I have access to the key, it would work, but I don't think that exists.
> MAPPING.transform_values { |_, k| self[k] }['UTC'].name
=> "UTC"There was a problem hiding this comment.
Sorry about that - you can use each_with_object to get both the key and the value, e.g.
@zones_map ||= MAPPING.each_with_object({}) { |(name, _), zones| zones[name] = self[name] }
activesupport/test/time_zone_test.rb
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| class TimeZoneTest < ActiveSupport::TestCase | |||
| include TimeZoneTestHelpers | |||
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| def setup | |||
| # Clear memoized time zone data on TimeZone class | |||
| ActiveSupport.send(:remove_const, :TimeZone) if ActiveSupport.const_defined?(:TimeZone) | |||
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Still not happy with this - I'd rather we add a nodoc public clear method on AS::TimeZone to explicitly clear the cache and then use that in the test.
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Thanks @pixeltrix! Could you please also close #7245? |
The def with blank `()` was newly added in #31176, but we have not used the blank `()` style in most part of our code base. So I've enabled `Style/DefWithParentheses` to prevent to newly added the code.
Summary
If you call
ActiveSupport::TimeZone.allbefore you look up anyActiveSupport::TimeZones by name, then all calls toActiveSupport::TimeZone.allfor the lifetime of the program will return a collection ofActiveSupport::TimeZones corresponding to the 151 "meaningful" time zone identifiers described byActiveSupport::TimeZone::MAPPING.If, however, you look up a time zone by a name that is not a key of
ActiveSupport::TimeZone::MAPPINGbefore making a call toActiveSupport::TimeZone.all, then the collection returned from all calls to that method will contain the time zone you looked up.Abridged Timeline
ActiveSupport::TimeZone.allreturns inconsistent output, but instead thatActionView::Helpers::FormOptionsHelper#time_zone_options_for_selectshould return a<select>element that always contained theselectedtime zone, regardless of whether or not that time zone was a member ofActiveSupport::TimeZone.all.time_zone_options_for_select. I do not think this solution fixes the actual problem since it does not remove the dependency ofActiveSupport::TimeZone.allfromtime_zone_options_for_select. As long as the former returns inconsistent output, so will the latter.ActiveSupport::TimeZone.all. This has the effect that any time you callActiveSupport::TimeZone.all, you get all time zones currently known (not just the ones fromActiveSupport::TimeZone::MAPPING). This PR is closed because it would introduce a performance regression. It's proposed to keep the cache around, but to invalidate it when we discover a new time zone.ActiveSupport::TimeZone.allto return only time zones that are inActiveSupport::TimeZone::MAPPING. I think this is absolutely 100% correct.