Yes, making Delays work accurately wrt wall-clock time would be more work now that I think about it. This seems to be better handled in a higher-level object.

- Bert -

On 2013-08-07, at 16:16, Bob Arning <arning315 at comcast.net> wrote:

> I was thinking about that, but I suspect there are use cases for both image time and real-world time. Maybe something like
> 
> (Delay until: someRealTime) wait
> 
> would meet the need the current Delay does not.
> 
> Cheers,
> Bob
> 
> On 8/7/13 9:54 AM, Bert Freudenberg wrote:
>> That has to be one of the oldest bugs! It's been there forever. I just committed that to trunk.
>> 
>> There is still a problem though. Squeak's delays (with Bob's fix) are based on image "running time". That is, if I have a 1 hour delay and snapshot the image after 45 minutes, on the next day it will expire 15 minutes after starting the image.
>> 
>> But arguably a delay should really expire by the same wall-clock time as when it was scheduled, even across snapshots. This is how it was handled in Smalltalk-80. Here's the ST80 code:
>> 
>> Delay>>preSnapshot
>>  "convert from local millisecond clock to milliseconds since Jan. 1 1901"
>>  pendingDelay _ resumptionTime - Time millisecondClockValue.
>>  resumptionTime _ Time totalSeconds * 1000 + pendingDelay
>> 
>> Delay>>postSnapshot
>>  "convert from milliseconds since Jan. 1 1901 to local millisecond clock"
>>  pendingDelay _ resumptionTime - (Time totalSeconds * 1000).
>>  pendingDelay _ pendingDelay max: 0.
>>  resumptionTime _ Time millisecondClockValue + pendingDelay
>> 
>> Of course, we would have to use UTC nowadays but I still think re-implementing this would be a good idea.
>> 
>> In any case, the fix makes the Delay snapshotting behavior at least predictable :)
>> 
>> - Bert -
>> 
>> On 2013-08-06, at 21:57, Bob Arning <arning315 at comcast.net> wrote:
>> 
>>> Well, this seems to fix it:
>>> 
>>> 'From Squeak4.4 of 1 March 2013 [latest update: #12489] on 6 August 2013 at 3:39:29 pm'!
>>> 
>>> !Delay class methodsFor: 'snapshotting' stamp: 'raa 8/6/2013 15:22'!
>>> restoreResumptionTimes
>>>     "Private!! Restore the resumption times of all scheduled Delays after a snapshot or clock roll-over. This method should be called only while the AccessProtect semaphore is held."
>>> 
>>>     | newBaseTime |
>>>     newBaseTime := Time millisecondClockValue.
>>>     SuspendedDelays do: [:d | d adjustResumptionTimeOldBase: 0 newBase: newBaseTime].
>>>     ActiveDelay == nil ifFalse: [
>>>         ActiveDelay adjustResumptionTimeOldBase: 0 newBase: newBaseTime.
>>>     ].
>>>     ActiveDelayStartTime _ newBaseTime "<-----this"! !
>>> 
>>> Cheers,
>>> Bob
>>> 
>>> On 8/6/13 3:27 PM, tim Rowledge wrote:
>>>> Well the timer stuff has certainly been messed about with a lot since I last had to dig into it, but it looks like it *ought* to work ok.
>>>> 
>>>> The only likely culprit I can spot is some issue with adjusting the resumption times after the restart, but that would require some problem with the millisecond time prim.
>>>> 
>>>> 
>>>> tim
>>>> --
>>>> tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
>>>> Strange OpCodes: YVR: Branch to Vancouver
>>>> 
>>>> 
>>>> 
>>>> 
>>> 
>>> 
>> 
>> 
>> 
>> 
>> 
> 
> 

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