The Trunk: Chronology-Core-ul.55.mcz

Did anyone try that out in practice? I think am going to create an event in my calendar for 2020-10-25T03:00:00+0001 (time changeover in Germany ...) and will watch the Squeak watch :D

Best,

Christoph

---

Von: Squeak-dev <[hidden email]> im Auftrag von Levente Uzonyi <[hidden email]>
Gesendet: Freitag, 5. Juni 2020 17:52:18
An: The general-purpose Squeak developers list
Cc: [hidden email]
Betreff: Re: [squeak-dev] The Trunk: Chronology-Core-ul.55.mcz

 

Hi Christoph,

On Fri, 5 Jun 2020, Thiede, Christoph wrote:

>
> Hi Levente,
>
>
> > What's your use case where doing it more often would be beneficial?
>
>
> When I travel into another timezone, I would not suspect my image to take 30 minutes to show the right time again. My android clock updates within seconds.

While the change makes it possible to support that use case, my intention
was to make images detect DST changes. By reducing updateInterval to a few
seconds, that use case can be supported as well. However, the smaller the
value is, the larger the overhead is. But it may still be insignificant.


Levente

>
> Best,
> Christoph
>
> __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
> Von: Squeak-dev <[hidden email]> im Auftrag von Levente Uzonyi <[hidden email]>
> Gesendet: Freitag, 5. Juni 2020 13:56:37
> An: The general-purpose Squeak developers list
> Cc: [hidden email]
> Betreff: Re: [squeak-dev] The Trunk: Chronology-Core-ul.55.mcz  
> Hi Christoph,
>
> On Fri, 5 Jun 2020, Thiede, Christoph wrote:
>
> >
> > Hi Levente,
> >
> >
> > > Automatically update the time zone cached by the VM every 30 minutes
> >
> >
> > In which scenario is a clock helpful that takes half an hour to set itself correctly?
>
> What's your use case where doing it more often would be beneficial?
>
>
> Levente
>
> >
> > Best,
> > Christoph
> >
> > _________________________________________________________________________________________________________________________________________________________________________________________________________________________________
> > Von: Squeak-dev <[hidden email]> im Auftrag von [hidden email] <[hidden email]>
> > Gesendet: Sonntag, 31. Mai 2020 00:12:42
> > An: [hidden email]; [hidden email]
> > Betreff: [squeak-dev] The Trunk: Chronology-Core-ul.55.mcz  
> > Levente Uzonyi uploaded a new version of Chronology-Core to project The Trunk:
> > http://source.squeak.org/trunk/Chronology-Core-ul.55.mcz
> >
> > ==================== Summary ====================
> >
> > Name: Chronology-Core-ul.55
> > Author: ul
> > Time: 31 May 2020, 12:10:20.250221 am
> > UUID: ea36b609-177c-405a-b64e-9988deb3d26e
> > Ancestors: Chronology-Core-nice.52
> >
> > Automatically update the time zone cached by the VM every 30 minutes:
> > - copied and modified Eliot's accessor to primitive 243 to do the actual updating (Time class >> #primitiveUpdateTimeZone)
> > - update happens when Time class >> #posixMicrosecondClockWithOffset or Time class >> #posixMicrosecondClockWithOffset: are sent. Other low-level accessors of the VM time zone are not updating the cached time zone value (e.g.
> > Time class >> #localMicrosecondClockPrimitive)
> > - actual update happens in Time class >> #updateTimeZoneCacheAt:
> > - postscript activates the update mechanism which can be turned off by evaluating [ Time classPool at: #UpdateVMTimeZoneCacheAt put: nil ]
> >
> > Other changes:
> > - do not send Time class >> #initialize from DateAndTime class >> #startUp:. Let Time have its own #startUp: method instead. Postscript adds Time to the startUpList before DateAndTime.
> > - do not send super initialize from DateAndTime class >> #initialize
> > - do not send #automaticTimezone to DateAndTime on startup, because that's just an accessor with no side effects
> > - do not overwrite set variables in Time class >> #initialize
> > - assert that the value passed to Time class >> #clockPolicy: is one of the known values
> >
> > =============== Diff against Chronology-Core-nice.52 ===============
> >
> > Item was changed:
> >   ----- Method: DateAndTime class>>initialize (in category 'initialize-release') -----
> >   initialize
> >  
> > -        super initialize.
> > -
> >          ClockProvider := Time.
> >          PosixEpochJulianDays := 2440588.
> >          InitializeFromPrimitive := self canInitializeFromPrimitive.
> >          Smalltalk addToStartUpList: self.
> >          self startUp: true
> >   !
> >
> > Item was changed:
> >   ----- Method: DateAndTime class>>startUp: (in category 'system startup') -----
> >   startUp: startingAfresh
> >          "Set local timezone"
> >          startingAfresh
> >                  ifTrue: [InitializeFromPrimitive := self canInitializeFromPrimitive.
> >                          Time initialize. "set LastClockTick to 0".
> > +                        self now]!
> > -                        self now.
> > -                        self automaticTimezone]!
> >
> > Item was changed:
> >   Magnitude subclass: #Time
> >          instanceVariableNames: 'seconds nanos'
> > +        classVariableNames: 'ClockPolicy HighResClockTicksPerMillisecond LastClockTick UpdateVMTimeZoneCacheAt UseHighResClockForTiming'
> > -        classVariableNames: 'ClockPolicy HighResClockTicksPerMillisecond LastClockTick UseHighResClockForTiming'
> >          poolDictionaries: 'ChronologyConstants'
> >          category: 'Chronology-Core'!
> >  
> >   !Time commentStamp: 'dew 10/23/2004 17:58' prior: 0!
> >   This represents a particular point in time during any given day.  For example, '5:19:45 pm'.
> >  
> >   If you need a point in time on a particular day, use DateAndTime.  If you need a duration of time, use Duration.
> >   !
> >
> > Item was changed:
> >   ----- Method: Time class>>clockPolicy: (in category 'class initialization') -----
> >   clockPolicy: aSymbol
> >          "When sequencial calls are made to DateAndTime now, it may be desirable to
> >          force the system clock to be monotonic, and it may be desirable for the clock
> >          to appear to be strictly increasing with no repeat values. The ClockPolicy
> >          identifies which of several possible strategies to use.
> >  
> >          Allowable values are
> >                  #acceptPlatformTime
> >                  #monotonicAllowDuplicates
> >                  #monotonicForceMicrosecondIncrement
> >                  #monotonicForceNanosecondIncrement "
> >  
> > +        self assert: (
> > +                #(
> > +                        acceptPlatformTime
> > +                        monotonicAllowDuplicates
> > +                        monotonicForceMicrosecondIncrement
> > +                        monotonicForceNanosecondIncrement) includes: aSymbol).
> >          ClockPolicy := aSymbol!
> >
> > Item was changed:
> >   ----- Method: Time class>>initialize (in category 'class initialization') -----
> >   initialize
> > +        " self initialize "
> > -        "Time initialize"
> >  
> > +        LastClockTick ifNil: [ LastClockTick := 0 ].
> > -        "Initialize at startup time to protect for the case of an image saved with bad LastClockTick"
> > -        LastClockTick := 0.
> >         
> > +        HighResClockTicksPerMillisecond ifNil: [ HighResClockTicksPerMillisecond := 0 ].
> > -        HighResClockTicksPerMillisecond := 0.
> >  
> > +        ClockPolicy ifNil: [
> > +                "self clockPolicy: #acceptPlatformTime."
> > +                self clockPolicy: #monotonicAllowDuplicates.
> > +                "self clockPolicy: #monotonicForceMicrosecondIncrement."
> > +                "self clockPolicy: #monotonicForceNanosecondIncrement." ]!
> > -        "self clockPolicy: #acceptPlatformTime."
> > -        self clockPolicy: #monotonicAllowDuplicates.
> > -        "self clockPolicy: #monotonicForceMicrosecondIncrement."
> > -        "self clockPolicy: #monotonicForceNanosecondIncrement."
> > - !
> >
> > Item was changed:
> >   ----- Method: Time class>>posixMicrosecondClockWithOffset (in category 'clock') -----
> >   posixMicrosecondClockWithOffset
> >          "Answer an array with local microseconds since the Posix epoch and the
> >          current seconds offset from GMT in the local time zone."
> >  
> > +        | array posixUtcValue |
> > -        | array utcValue |
> >          array := self primPosixMicrosecondClockWithOffset.
> > +        posixUtcValue := array at: 1.
> > +        (self updateTimeZoneCacheAt: posixUtcValue) ifTrue: [ "Time zone may have changed: fetch again."
> > +                self primPosixMicrosecondClockWithOffset: array.
> > +                posixUtcValue := array at: 1 ].
> >          ClockPolicy caseOf: {
> >                  [#acceptPlatformTime] -> [^ array] .
> >                  [#monotonicAllowDuplicates] -> [
> > +                        posixUtcValue > LastClockTick
> > +                                ifTrue: [LastClockTick := posixUtcValue]
> > -                        utcValue := array at: 1.
> > -                        utcValue > LastClockTick
> > -                                ifTrue: [LastClockTick := utcValue]
> >                                  ifFalse: [array at: 1 put: LastClockTick]] .
> >                  [#monotonicForceMicrosecondIncrement] -> [
> > +                        posixUtcValue > LastClockTick
> > +                                ifTrue: [LastClockTick := posixUtcValue]
> > -                        utcValue := array at: 1.
> > -                        utcValue > LastClockTick
> > -                                ifTrue: [LastClockTick := utcValue]
> >                                  ifFalse: [LastClockTick := LastClockTick + 1. "add one microsecond"
> >                                          array at: 1 put: LastClockTick]] .
> >                  [#monotonicForceNanosecondIncrement] -> [
> > +                        posixUtcValue > LastClockTick
> > +                                ifTrue: [LastClockTick := posixUtcValue]
> > -                        utcValue := array at: 1.
> > -                        utcValue > LastClockTick
> > -                                ifTrue: [LastClockTick := utcValue]
> >                                  ifFalse: [LastClockTick := LastClockTick + (1 / 1000). "add one nanosecond"
> >                                          array at: 1 put: LastClockTick]]
> >          } otherwise: [].
> > +        ^array!
> > -        ^array
> > -
> > - !
> >
> > Item was changed:
> >   ----- Method: Time class>>posixMicrosecondClockWithOffset: (in category 'clock') -----
> >   posixMicrosecondClockWithOffset: aDateAndTime
> >          "Initialize aDateAndTime initialized with local microseconds since the Posix
> >          epoch and the current seconds offset from GMT in the local time zone."
> >  
> > +        | posixUtcValue |
> > -
> > -        | utcValue |
> >          self primPosixMicrosecondClockWithOffset: aDateAndTime.
> > +        posixUtcValue := aDateAndTime utcMicroseconds.
> > +        (self updateTimeZoneCacheAt: posixUtcValue) ifTrue: [ "Time zone may have changed: fetch again."
> > +                self primPosixMicrosecondClockWithOffset: aDateAndTime .
> > +                posixUtcValue := aDateAndTime utcMicroseconds ].
> >          ClockPolicy caseOf: {
> >                  [#acceptPlatformTime] -> [^ aDateAndTime] .
> >                  [#monotonicAllowDuplicates] -> [
> > +                        posixUtcValue > LastClockTick
> > +                                ifTrue: [LastClockTick := posixUtcValue]
> > -                        utcValue := aDateAndTime utcMicroseconds.
> > -                        utcValue > LastClockTick
> > -                                ifTrue: [LastClockTick := utcValue]
> >                                  ifFalse: [aDateAndTime utcMicroseconds: LastClockTick]] .
> >                  [#monotonicForceMicrosecondIncrement] -> [
> > +                        posixUtcValue > LastClockTick
> > +                                ifTrue: [LastClockTick := posixUtcValue]
> > -                        utcValue := aDateAndTime utcMicroseconds.
> > -                        utcValue > LastClockTick
> > -                                ifTrue: [LastClockTick := utcValue]
> >                                  ifFalse: [LastClockTick := LastClockTick + 1. "add one microsecond"
> >                                          aDateAndTime utcMicroseconds: LastClockTick]] .
> >                  [#monotonicForceNanosecondIncrement] -> [
> > +                        posixUtcValue > LastClockTick
> > +                                ifTrue: [LastClockTick := posixUtcValue]
> > -                        utcValue := aDateAndTime utcMicroseconds.
> > -                        utcValue > LastClockTick
> > -                                ifTrue: [LastClockTick := utcValue]
> >                                  ifFalse: [LastClockTick := LastClockTick + (1 / 1000). "add one nanosecond"
> >                                          aDateAndTime utcMicroseconds: LastClockTick]]
> >          } otherwise: [].
> > +        ^aDateAndTime!
> > -        ^aDateAndTime
> > - !
> >
> > Item was added:
> > + ----- Method: Time class>>primitiveUpdateTimeZone (in category 'clock') -----
> > + primitiveUpdateTimeZone
> > +        "Update the VMs notion of the current time zone.  The VM sets its notion
> > +         of the time zone once at start-up.  If one wants the VM to keep its notion
> > +         up-to-date arrange to invoke this primitive periodically."
> > +       
> > +        <primitive: 243>
> > +        ^nil "Return nil instead of self to indicate that the primitive failed."!
> >
> > Item was added:
> > + ----- Method: Time class>>startUp: (in category 'system startup') -----
> > + startUp: resuming
> > +
> > +        resuming ifTrue: [
> > +                LastClockTick := 0 ]!
> >
> > Item was added:
> > + ----- Method: Time class>>updateTimeZoneCacheAt: (in category 'clock') -----
> > + updateTimeZoneCacheAt: posixUtcMicrosecondClock
> > +        "Tell the VM to update its cached time zone value if the POSIX UTC time reached the valute stored in UpdateVMTimeZoneCacheAt has been reached. Assume that posixUtcMicrosecondClock is an integer with the current POSIX
> > UTC microsecond clock value. Return true when the cache was updated to indicate that the time zone may have changed."
> > +
> > +        | updateInterval |
> > +        UpdateVMTimeZoneCacheAt ifNil: [
> > +                "Automatic update is disabled."
> > +                ^false ].
> > +        posixUtcMicrosecondClock < UpdateVMTimeZoneCacheAt ifTrue: [ ^false ].
> > +        self primitiveUpdateTimeZone ifNil: [
> > +                "The primitive failed."
> > +                ^false ].
> > +        updateInterval := 1800000000. "This could be a preference but 30 minutes matches all upcoming DST change times."
> > +        UpdateVMTimeZoneCacheAt := posixUtcMicrosecondClock // updateInterval + 1 * updateInterval "Round up posixUtcMicrosecondClock to the next multiple of updateInterval.".
> > +        ^true!
> >
> > Item was changed:
> > + (PackageInfo named: 'Chronology-Core') postscript: '"Make sure UpdateVMTimeZoneCacheAt of Time is initialized."
> > + Time classPool at: #UpdateVMTimeZoneCacheAt put: 0.
> > + "Separated Time''s startup duties from DateAndTime."
> > + Smalltalk addToStartUpList: Time before: DateAndTime'!
> > - (PackageInfo named: 'Chronology-Core') postscript: 'DateAndTime startUp: true.
> > - HashedCollection rehashAll.
> > - '!
> >
> >
> >
> >
>
>