Make ActiveSupport::TimeZone.all independent of previous lookups #31176
Conversation
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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) | |||
sgrif
Nov 17, 2017
Contributor
This setup is overly coupled to the internal details of the implementation
This setup is overly coupled to the internal details of the implementation
cjlarose
Nov 17, 2017
Author
Contributor
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.
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]] }] |
pixeltrix
Nov 20, 2017
Member
This can be written as:
@zones_map ||= MAPPING.transform_values { |tz| self[tz] }
This can be written as:
@zones_map ||= MAPPING.transform_values { |tz| self[tz] }
cjlarose
Nov 20, 2017
•
Author
Contributor
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"
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"
pixeltrix
Nov 21, 2017
Member
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] }
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] }| @@ -8,6 +8,12 @@ | |||
| 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) | |||
pixeltrix
Nov 20, 2017
Member
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.
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.