[squeak-dev] The Inbox: Chronology-Core-cmm.53.mczLevente Uzonyi leves at caesar.elte.huThu Apr 30 00:29:19 UTC 2020
Hi Chris, On Wed, 29 Apr 2020, Chris Muller wrote: > One of the main benefits of converting former Chronology's internal 3-element Array to an Integer should be to be able to easily translate back-and-forth between Integer and object (DateAndTime) representations. With this, > when creating log entries, you can simply access Time class>>#microsecondClock, which creates no garbage. Then, to display the log, DateAndTime class>>#fromMicroseconds: will instantiate the proper instance of that time. You may as well store the posix microseconds and recreate the DateAndTime instance with #utcMicroseconds:offset:. To get the clock value, you can either use #primPosixMicrosecondClockWithOffset: directly or you can use primitive 240 and subtract the offset yourself. That way you can avoid introducing a new API serving only a very specific goal. The VM clock is not monotonic, so you may want to use Time class >> #posixMicrosecondClockWithOffset: to get monotonic values. Because of the above and because of the non-descriptive names, -1 from me for #fromMicroseconds: and #asMicroseconds. Also -1 for #microsecondClock. That would be the third (actually fourth but one was a typo) name for that primitive, and I'm bored migrating code from one to another because someone didn't like some part of the selector. > > The "utc" prefix seems to be related to the name that Dave gave his alternative version of Chronology, and retained some of it when it was integrated into trunk. I don't recall whether Time>>#utcMicrosecond was part of that, > but if we can be willing to drop the prefix for that one selector, the API won't have this ambiguity that confused me for an evening. The utc prefix tells me about the time zone offset. Its use is clear; removing it would introduce amiguity. Dave's "new" implementation uses the posix epoch. I'm surprised people who took part in its discussion 4-5 years ago seem to not be aware of that. Levente > > Best, > Chris > > > On Wed, Apr 29, 2020 at 6:51 PM <commits at source.squeak.org> wrote: > Chris Muller uploaded a new version of Chronology-Core to project The Inbox: > http://source.squeak.org/inbox/Chronology-Core-cmm.53.mcz > > ==================== Summary ==================== > > Name: Chronology-Core-cmm.53 > Author: cmm > Time: 29 April 2020, 6:51:53.53317 pm > UUID: b930b208-c85e-4c6b-8254-2837493384bd > Ancestors: Chronology-Core-nice.52 > > - Extend the API to allow an integral representation of DateAndTime's, by introducing > > DateAndTime class>>#fromMicroseconds: > DateAndTime>>#asMicroseconds > > which go along with the existing API: > > DateAndTime class>>#fromSeconds: > DateAndTime>>#asSeconds > > - Every Squeak with the substring "utcMicrosecond" in the selector name refers to the number of microseconds since the POSIX epoch (1/1/1971 at 00:00:00.000), __except for one__: Time utcMicroseconds. Therefore, to > avoid astonishment when using it with the "utc" API of DateAndTime, rename it without the "utc" prefix. > > =============== Diff against Chronology-Core-nice.52 =============== > > Item was added: > + ----- Method: DateAndTime class>>fromMicroseconds: (in category 'smalltalk-80') ----- > + fromMicroseconds: anInteger > + "Answer a DateAndTime anInteger microseconds since the Squeak epoch: 1 January 1901." > + ^ self > + utcMicroseconds: anInteger - (self epochOffset * 1000000) > + offset: self localOffsetSeconds! > > Item was added: > + ----- Method: DateAndTime>>asMicroseconds (in category 'smalltalk-80') ----- > + asMicroseconds > + "Return the number of microseconds since the Squeak epoch, 1/1/1901 @ 00:00:00." > + ^ utcMicroseconds + self class epochOffsetMicros! > > Item was changed: > ----- Method: Time class>>estimateHighResClockTicksPerMillisecond (in category 'clock') ----- > estimateHighResClockTicksPerMillisecond > > | t0 t1 t2 t3 | > > "Count the ticks ellapsed during a 10ms busy loop" > + t0 := Time microsecondClock + 200. > + [Time microsecondClock >= t0] whileFalse. > - t0 := Time utcMicrosecondClock + 200. > - [Time utcMicrosecondClock >= t0] whileFalse. > t1 := self highResClock. > + [Time microsecondClock >= (t0 + 10000)] whileFalse. > + t1 := self highResClock - t1 * 1000 // (Time microsecondClock - t0). > - [Time utcMicrosecondClock >= (t0 + 10000)] whileFalse. > - t1 := self highResClock - t1 * 1000 // (Time utcMicrosecondClock - t0). > > "Count the ticks ellapsed during a 20ms busy loop" > + t0 := Time microsecondClock + 200. > + [Time microsecondClock >= t0] whileFalse. > - t0 := Time utcMicrosecondClock + 200. > - [Time utcMicrosecondClock >= t0] whileFalse. > t2 := self highResClock. > + [Time microsecondClock >= (t0 + 20000)] whileFalse. > + t2 := self highResClock - t2 * 1000 // (Time microsecondClock - t0). > - [Time utcMicrosecondClock >= (t0 + 20000)] whileFalse. > - t2 := self highResClock - t2 * 1000 // (Time utcMicrosecondClock - t0). > > "Count the ticks ellapsed during a 30ms busy loop" > + t0 := Time microsecondClock + 200. > + [Time microsecondClock >= t0] whileFalse. > - t0 := Time utcMicrosecondClock + 200. > - [Time utcMicrosecondClock >= t0] whileFalse. > t3 := self highResClock. > + [Time microsecondClock >= (t0 + 30000)] whileFalse. > + t3 := self highResClock - t3 * 1000 // (Time microsecondClock - t0). > - [Time utcMicrosecondClock >= (t0 + 30000)] whileFalse. > - t3 := self highResClock - t3 * 1000 // (Time utcMicrosecondClock - t0). > > "Take the median of the 3 estimates as the best" > ^ t1 <= t2 > ifTrue: [t2 <= t3 > ifTrue: [t2] > ifFalse: [t1 <= t3 > ifTrue: [t3] > ifFalse: [t1]]] > ifFalse: [t1 <= t3 > ifTrue: [t1] > ifFalse: [t2 <= t3 > ifTrue: [t3] > ifFalse: [t2]]]! > > Item was changed: > ----- Method: Time class>>localMicrosecondClock (in category 'clock') ----- > localMicrosecondClock > "Answer the local microseconds since the Smalltalk epoch (January 1st 1901, the start of the 20th century). > The value is derived from the current UTC wallclock time and the image's current notion of time zone." > + ^self microsecondClock + (DateAndTime localOffset asSeconds * 1000000)! > - ^self utcMicrosecondClock + (DateAndTime localOffset asSeconds * 1000000)! > > Item was added: > + ----- Method: Time class>>microsecondClock (in category 'clock') ----- > + microsecondClock > + "Answer the UTC microseconds since the Smalltalk epoch (January 1st 1901, the start of the 20th century). > + The value is derived from the Posix epoch with a constant offset corresponding to elapsed microseconds > + between the two epochs according to RFC 868." > + <primitive: 240> > + ^0! > > Item was changed: > ----- Method: Time class>>microsecondsToRun: (in category 'general inquiries') ----- > microsecondsToRun: timedBlock > "Answer the number of microseconds timedBlock takes to return its value." > > | startUsecs | > (self useHighResClockForTiming and: [self highResClock ~= 0]) > ifTrue: [ ^(self nanosecondsToRunHighRes: timedBlock) + 500 // 1000]. > + startUsecs := self microsecondClock. > - startUsecs := self utcMicrosecondClock. > timedBlock value. > + ^self microsecondClock - startUsecs! > - ^self utcMicrosecondClock - startUsecs! > > Item was changed: > ----- Method: Time class>>millisecondClockValue (in category 'general inquiries') ----- > millisecondClockValue > "Answer the value of the millisecond clock." > > + ^self microsecondClock // 1000! > - ^self utcMicrosecondClock // 1000! > > Item was changed: > ----- Method: Time class>>nanosecondsToRun: (in category 'general inquiries') ----- > nanosecondsToRun: timedBlock > "Answer the number of nanoseconds timedBlock takes to return its value. > Use high resolution clock if available and preferred." > > | startUsecs | > (self useHighResClockForTiming and: [self highResClock ~= 0]) > ifTrue: [ ^(self nanosecondsToRunHighRes: timedBlock)]. > "Fallback to microseconds clock" > + startUsecs := self microsecondClock. > - startUsecs := self utcMicrosecondClock. > timedBlock value. > + ^self microsecondClock - startUsecs * 1000! > - ^self utcMicrosecondClock - startUsecs * 1000! > > Item was added: > + ----- Method: Time class>>totalMicroSeconds (in category 'smalltalk-80') ----- > + totalMicroSeconds > + "Answer the total seconds since the Squeak epoch: 1 January 1901, in local time." > + > + ^self localMicrosecondClock // 1000000! > > Item was changed: > ----- Method: Time class>>utcMicrosecondClock (in category 'clock') ----- > utcMicrosecondClock > "Answer the UTC microseconds since the Smalltalk epoch (January 1st 1901, the start of the 20th century). > The value is derived from the Posix epoch with a constant offset corresponding to elapsed microseconds > between the two epochs according to RFC 868." > <primitive: 240> > + self deprecated: 'Use #microsecondClock'. > ^0! > > > >
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