Lazily initialize the time zone cache

[KristofferC]

This avoids having to compile a bunch of code in __init__ and improves the load time of the package (on Julia 1.11) from:

julia> @time_imports import TimeZones
...
              ┌ 2.6 ms TimeZones.TZData.__init__() 92.83% compilation time
               ├ 237.9 ms TimeZones.__init__() 94.11% compilation time (89% recompilation)
    276.3 ms  TimeZones 81.90% compilation time (88% recompilation)

julia> @time_imports import TimeZones
...
     17.5 ms  TimeZones 16.03% compilation time

The change in performance of the functions is (in my opinion) acceptable.

After:

julia> using BenchmarkTools, TimeZones

julia> @btime istimezone("Europe/Warsaw")
  48.068 ns (1 allocation: 16 bytes)
true

Before:

julia> @btime istimezone("Europe/Warsaw")
  45.356 ns (1 allocation: 16 bytes)
true

[KristofferC]

I commented out this because otherwise it just logs randomly when you call a function and the cache initializes. It feels a bit pointless in the first place as well.

[omus]

The point was to alert users that the environmental JULIA_TZ_VERSION was specified to a different version than TimeZones.jl would use by default. I'm not opposed to dropping this but it was informative

[KristofferC]

Okay but it will just appear at some random point now without any context to the user.

[omus]

I think a reasonable compromise is to display a message during the __init__ and perform the loading like you propose

[omus]

Overall I'm good with this. Just a couple of things to clean up

[omus]

Rebased this PR now that #456 has been merged

[omus]

Posting some benchmarks from my machine so I can do some refactoring without losing the performance gains.

Before this PR with Julia 1.11.0-beta1 on an M1 MacBook

julia> @time_imports import TimeZones
...
               ┌ 4.4 ms TimeZones.TZData.__init__() 53.17% compilation time
               ├ 318.6 ms TimeZones.__init__() 85.10% compilation time (93% recompilation)
    690.8 ms  TimeZones 59.42% compilation time (85% recompilation)

julia> using BenchmarkTools, TimeZones

julia> @btime istimezone("Europe/Warsaw");
  77.314 ns (1 allocation: 16 bytes)

With this PR with Julia 1.11.0-beta1 on an M1 MacBook

julia> @time_imports import TimeZones
...
               ┌ 3.7 ms TimeZones.TZData.__init__() 56.80% compilation time
               ├ 0.0 ms TimeZones.__init__()
    107.0 ms  TimeZones 83.43% compilation time (53% recompilation)

julia> using BenchmarkTools, TimeZones

julia> @btime istimezone("Europe/Warsaw");
  80.966 ns (1 allocation: 16 bytes)

[omus]

Iterating on the `istimezone` internals

Iteration 1

function istimezone(str::AbstractString, mask::Class=Class(:DEFAULT))
    # Start by performing quick FIXED class test
    if mask & Class(:FIXED) != Class(:NONE) && occursin(FIXED_TIME_ZONE_REGEX, str)
        return true
    end

    # Checks against pre-compiled time zones
    tz, class = get(get_tz_cache(), str, (nothing, Class(:NONE)))
    return tz !== nothing && mask & class != Class(:NONE)
end

julia> @time_imports import TimeZones
...
               ┌ 2.7 ms TimeZones.TZData.__init__() 77.28% compilation time
               ├ 0.0 ms TimeZones.__init__()
    106.6 ms  TimeZones 84.49% compilation time (53% recompilation)

julia> using BenchmarkTools, TimeZones

julia> @btime istimezone("Europe/Warsaw");
  95.032 ns (2 allocations: 64 bytes)

Iteration 2

function istimezone(str::AbstractString, mask::Class=Class(:DEFAULT))
    # Start by performing quick FIXED class test
    if mask & Class(:FIXED) != Class(:NONE) && occursin(FIXED_TIME_ZONE_REGEX, str)
        return true
    end

    # Checks against pre-compiled time zones
    tz_class = get(get_tz_cache(), str, nothing)
    tz_class === nothing && return false
    tz, class = tz_class
    return mask & class != Class(:NONE)
end

julia> @time_imports import TimeZones
...
               ┌ 2.5 ms TimeZones.TZData.__init__() 78.26% compilation time
               ├ 0.0 ms TimeZones.__init__()
    103.5 ms  TimeZones 83.75% compilation time (52% recompilation)

julia> using BenchmarkTools, TimeZones

julia> @btime istimezone("Europe/Warsaw");
  75.789 ns (1 allocation: 16 bytes)

Iteration 3

function istimezone(str::AbstractString, mask::Class=Class(:DEFAULT))
    # Start by performing quick FIXED class test
    if mask & Class(:FIXED) != Class(:NONE) && occursin(FIXED_TIME_ZONE_REGEX, str)
        return true
    end

    # Checks against pre-compiled time zones
    _, class = get(get_tz_cache(), str, (UTC_ZERO, Class(:NONE)))
    return mask & class != Class(:NONE)
end

julia> @time_imports import TimeZones
...
               ┌ 3.1 ms TimeZones.TZData.__init__() 66.09% compilation time
               ├ 0.0 ms TimeZones.__init__()
    103.3 ms  TimeZones 83.89% compilation time (52% recompilation)

julia> using BenchmarkTools, TimeZones

julia> @btime istimezone("Europe/Warsaw");
  80.492 ns (1 allocation: 16 bytes)

Iteration 4

function istimezone(str::AbstractString, mask::Class=Class(:DEFAULT))
    # Start by performing quick FIXED class test
    if mask & Class(:FIXED) != Class(:NONE) && occursin(FIXED_TIME_ZONE_REGEX, str)
        return true
    end

    # Checks against pre-compiled time zones
    class = get(get_tz_cache(), str, (UTC_ZERO, Class(:NONE)))[2]
    return mask & class != Class(:NONE)
end

julia> @time_imports import TimeZones
...
               ┌ 2.8 ms TimeZones.TZData.__init__() 79.89% compilation time
               ├ 0.0 ms TimeZones.__init__()
    102.1 ms  TimeZones 83.99% compilation time (54% recompilation)

julia> using BenchmarkTools, TimeZones

julia> @btime istimezone("Europe/Warsaw");
  75.610 ns (1 allocation: 16 bytes)

[omus]

Commit 5701f3a

julia> @time_imports import TimeZones
...
               ┌ 3.1 ms TimeZones.TZData.__init__() 77.56% compilation time
               ├ 0.0 ms TimeZones.__init__()
    106.5 ms  TimeZones 84.26% compilation time (54% recompilation)

julia> using BenchmarkTools, TimeZones

julia> @btime istimezone("Europe/Warsaw");
  78.689 ns (1 allocation: 16 bytes)

Commit b5948fc

julia> @time_imports import TimeZones
...
      0.6 ms  Mocking
               ┌ 2.5 ms TimeZones.TZData.__init__() 81.56% compilation time
               ├ 0.0 ms TimeZones.__init__()
    108.0 ms  TimeZones 79.75% compilation time (53% recompilation)

julia> using BenchmarkTools, TimeZones

julia> @btime istimezone("Europe/Warsaw");
  75.703 ns (1 allocation: 16 bytes)

Looks like I broke some tests in the process

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 91.66667% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 92.67%. Comparing base (2bc8f50) to head (d900457).
Report is 3 commits behind head on master.

Files	Patch %	Lines
src/build.jl	0.00%	1 Missing ⚠️
src/types/timezone.jl	95.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #457      +/-   ##
==========================================
- Coverage   92.79%   92.67%   -0.12%     
==========================================
  Files          39       39              
  Lines        1818     1830      +12     
==========================================
+ Hits         1687     1696       +9     
- Misses        131      134       +3     

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[omus]

Close to the finish line on this one. I'd like to recheck the performance with the fixed tests yet.