Perf: Cache ts offset guesses for quickDT #1579
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/easycla |
icambron
requested changes
Jan 22, 2024
src/datetime.js
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| function guessOffsetForZone(zone) { | ||
| if (!DateTime._zoneOffsetGuessCache[zone]) { | ||
| if (DateTime._zoneOffsetTs === undefined) { | ||
| DateTime._zoneOffsetTs = Settings.now(); |
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Should support clearing the cache here
test/datetime/dst.test.js
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| expect(d.hour).toBe(1); | ||
| expect(d.offset).toBe(-4 * 60); | ||
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| DateTime._zoneOffsetGuessCache = {}; |
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You could then use the resetCaches() function in here
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Looks pretty good. Just requested a few changes |
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Changed, thanks! |
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@schleyfox if you fix the conflicts, I'll merge this |
icambron
approved these changes
Mar 9, 2024
Previously we guessed by calling zone.offset(tsNow) on every construction of a date from date parts. This caches that result instead, saving a call to offset
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@icambron conflicts fixed. thanks. |
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This is part of a series of PRs based on performance work we have done to
improve a use-case involving parsing/formatting hundreds of thousands of dates
where luxon was the bottleneck.
This includes the commit from #1574 to establish the benchmark
Previously we guessed by calling zone.offset(tsNow) on every
construction of a date from date parts. This caches that result instead,
saving a call to offset. The tests verify that this works across DST boundaries when the cache holds an offset for the previous DST state from now.
For processes that live across a DST boundary and mostly handle current date times, this will mean the guess is wrong and we'll have to re-guess. Since we're caching one call to offset, this should be performance neutral to current behavior. Otherwise, we save a call.
Benchmark Comparison (
name | before | after | after/before):