Add subsec to `ActiveSupport::TimeWithZone#inspect` #38874

akinomaeni · 2020-04-04T14:05:28Z

Summary

Add subsec to ActiveSupport::TimeWithZone#inspect.

before

Time.at(1498099140).in_time_zone.inspect
# => "Thu, 22 Jun 2017 02:39:00 UTC +00:00"
Time.at(1498099140, 123456780, :nsec).in_time_zone.inspect
# => "Thu, 22 Jun 2017 02:39:00 UTC +00:00"
Time.at(1498099140 + Rational("1/3")).in_time_zone.inspect
# => "Thu, 22 Jun 2017 02:39:00 UTC +00:00"

after

Time.at(1498099140).in_time_zone.inspect
# => "Thu, 22 Jun 2017 02:39:00.000000000 UTC +00:00"
Time.at(1498099140, 123456780, :nsec).in_time_zone.inspect
# => "Thu, 22 Jun 2017 02:39:00.123456780 UTC +00:00"
Time.at(1498099140 + Rational("1/3")).in_time_zone.inspect
# => "Thu, 22 Jun 2017 02:39:00.333333333 UTC +00:00"

Other Information

Ruby 2.7 Time#inspect

It started inspecting sub-second of Time.
Rdoc Ticket Commit

$ docker run ruby:2.7.0-alpine ruby -e 'p Time.at(1498099140)'
2017-06-22 02:39:00 +0000
$ docker run ruby:2.7.0-alpine ruby -e 'p Time.at(1498099140, 123456780, :nsec)'
2017-06-22 02:39:00.12345678 +0000
$ docker run ruby:2.7.0-alpine ruby -e 'p Time.at(1498099140 + Rational("1/3"))'
2017-06-22 02:39:00 1/3 +0000

$ docker run ruby:2.6.5-alpine ruby -e 'p Time.at(1498099140)'
2017-06-22 02:39:00 +0000
$ docker run ruby:2.6.5-alpine ruby -e 'p Time.at(1498099140, 123456780, :nsec)'
2017-06-22 02:39:00 +0000
$ docker run ruby:2.6.5-alpine ruby -e 'p Time.at(1498099140 + Rational("1/3"))'
2017-06-22 02:39:00 +0000

Motivation

ActiveSupport::TimeWithZone#inspect does not display sub-second. And it confuses me that times having different sub-seconds look like the same time.

Database adapter: mysql2
create_table :songs { |t| t.datetime :released_at, precision: 6 }

# git branch => master
vagrant@rails-dev-box:/vagrant/my-test-app$ bin/rails c
Loading development environment (Rails 6.1.0.alpha)
irb(main):001:0> now = Time.current
=> Sat, 04 Apr 2020 13:37:58 UTC +00:00
irb(main):002:0> released_at = Song.new(released_at: now).released_at
=> Sat, 04 Apr 2020 13:37:58 UTC +00:00
irb(main):003:0> now == released_at
=> false
irb(main):004:0> now.nsec
=> 433841399
irb(main):005:0> released_at.nsec
=> 433841000

After the change it's clear.

# git branch => inspect-time-with-zone-subsec
vagrant@rails-dev-box:/vagrant/my-test-app$ bin/rails c
Loading development environment (Rails 6.1.0.alpha)
irb(main):001:0> now = Time.current
=> Sat, 04 Apr 2020 13:39:12.231596578 UTC +00:00
irb(main):002:0> released_at = Song.new(released_at: now).released_at
=> Sat, 04 Apr 2020 13:39:12.231596 UTC +00:00
irb(main):003:0> now == released_at
=> false

Time.at(1498099140).in_time_zone.inspect => "Thu, 22 Jun 2017 02:39:00 UTC +00:00" Time.at(1498099140, 123456780, :nsec).in_time_zone.inspect => "Thu, 22 Jun 2017 02:39:00.12345678 UTC +00:00" Time.at(1498099140 + Rational("1/3")).in_time_zone.inspect => "Thu, 22 Jun 2017 02:39:00 1/3 UTC +00:00"

kaspth

Interesting idea! Hopefully this should make it more obvious when times are different in minitest assertions too.

kaspth · 2020-04-05T21:42:12Z

activesupport/lib/active_support/time_with_zone.rb

@@ -139,7 +139,7 @@ def zone
    #
    #   Time.zone.now.inspect # => "Thu, 04 Dec 2014 11:00:25 EST -05:00"
    def inspect
-      "#{time.strftime('%a, %d %b %Y %H:%M:%S')} #{zone} #{formatted_offset}"
+      "#{time.strftime('%a, %d %b %Y %H:%M:%S')}#{formatted_subsec_with_delimiter} #{zone} #{formatted_offset}"


Can we get this via strftime in 2.7? Although it's potentially dangerous to make this Ruby version specific, there's a significant amount of code that it would be nice to trim away.

Looks like %L and %N are candidates:

%L - Millisecond of the second (000..999) %N - Fractional seconds digits, default is 9 digits (nanosecond) %3N millisecond (3 digits) %15N femtosecond (15 digits) %6N microsecond (6 digits) %18N attosecond (18 digits) %9N nanosecond (9 digits) %21N zeptosecond (21 digits) %12N picosecond (12 digits) %24N yoctosecond (24 digits)

@kaspth Thank you for your suggestion.

What do you think about changing the handling of rational subsecs that cannot be represented by integers even if subsec digits is increased?

Ruby implements its own subsec format without using strftime in Time#inspect.
https://github.com/ruby/ruby/blob/d827c718db32c07f025f88fd792e9407e19e66e1/time.c#L4143-L4157
So we cannot get the same formatted subsec via strftime.

case with the current formatted_subsec_with_delimiter.

irb(main):001:0> t1 = Time.at(1498099140 + Rational("2/7")).in_time_zone => Thu, 22 Jun 2017 02:39:00 2/7 UTC +00:00 irb(main):002:0> t2 = Time.at(1498099140, 285714285, :nsec).in_time_zone => Thu, 22 Jun 2017 02:39:00.285714285 UTC +00:00 irb(main):003:0> t1 == t2 => false

case with %9N

irb(main):001:0> t1 = Time.at(1498099140 + Rational("2/7")).in_time_zone => Thu, 22 Jun 2017 02:39:00.285714285 UTC +00:00 irb(main):002:0> t2 = Time.at(1498099140, 285714285, :nsec).in_time_zone => Thu, 22 Jun 2017 02:39:00.285714285 UTC +00:00 irb(main):003:0> t1 == t2 => false

In my opinion, I want to know the contents exactly with inspect, different from to_s and other formatting methods.

But if Rails team thinks that maintainability is more important than accuracy here, I would support it.

Updated doc 899d006

@kaspth Here is the patch with %9N akinomaeni@7582ed7. Should I push it to this PR?

Wow, that's cool! How does it look on Ruby 2.6? Feel free to push to here and get the build to show us.

irb(main):001:0> RUBY_VERSION => "1.9.3" irb(main):002:0> Time.now.strftime('%9N') => "437936000"

%9N is already available on Ruby 1.9. So no worry on 2.6.

The new thing in Ruby 2.7 is this change.

Ruby implements its own subsec format without using strftime in Time#inspect.
https://github.com/ruby/ruby/blob/d827c718db32c07f025f88fd792e9407e19e66e1/time.c#L4143-L4157

case with %9N

irb(main):001:0> t1 = Time.at(1498099140 + Rational("2/7")).in_time_zone => Thu, 22 Jun 2017 02:39:00.285714285 UTC +00:00 irb(main):002:0> t2 = Time.at(1498099140, 285714285, :nsec).in_time_zone => Thu, 22 Jun 2017 02:39:00.285714285 UTC +00:00 irb(main):003:0> t1 == t2 => false

This is on Ruby 2.5.5.

@kaspth Pushed!

The new thing in Ruby 2.7 is this change.

Ah, I see what you mean. I think using %9N covers it just enough. The potential issue with Rational doesn't bother me with what you've shown me.

Time.at(1498099140).in_time_zone.inspect => "Thu, 22 Jun 2017 02:39:00.000000000 UTC +00:00" Time.at(1498099140, 123456780, :nsec).in_time_zone.inspect => "Thu, 22 Jun 2017 02:39:00.123456780 UTC +00:00" Time.at(1498099140 + Rational("1/3")).in_time_zone.inspect => "Thu, 22 Jun 2017 02:39:00.333333333 UTC +00:00"

kaspth · 2020-04-11T01:54:01Z

Thanks for working on this! 🙏

rails-bot bot added the activesupport label Apr 4, 2020

kaspth reviewed Apr 5, 2020

View reviewed changes

akinomaeni added 2 commits April 11, 2020 08:09

Show subsec of Time.zone.now [ci skip]

899d006

kaspth merged commit 4d09472 into rails:master Apr 11, 2020

eugeneius mentioned this pull request Apr 14, 2021

ActiveSupport::TimeWithZone#inspect should include nsec in the output string #41971

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Add subsec to `ActiveSupport::TimeWithZone#inspect` #38874

Add subsec to `ActiveSupport::TimeWithZone#inspect` #38874

akinomaeni commented Apr 4, 2020 •

edited

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kaspth commented Apr 11, 2020

Add subsec to ActiveSupport::TimeWithZone#inspect #38874

Add subsec to ActiveSupport::TimeWithZone#inspect #38874

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akinomaeni commented Apr 4, 2020 • edited

Summary

Other Information

Ruby 2.7 Time#inspect

Motivation

kaspth left a comment

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case with the current formatted_subsec_with_delimiter.

case with %9N

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case with %9N

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kaspth commented Apr 11, 2020

Add subsec to `ActiveSupport::TimeWithZone#inspect` #38874

Add subsec to `ActiveSupport::TimeWithZone#inspect` #38874

akinomaeni commented Apr 4, 2020 •

edited

case with the current `formatted_subsec_with_delimiter`.

case with `%9N`

case with `%9N`