On Sat, Jan 12, 2019 at 02:45:17AM +0100, Levente Uzonyi wrote:
> On Fri, 11 Jan 2019, David T. Lewis wrote:
> 
> >On Sat, Jan 12, 2019 at 12:32:51AM +0100, Levente Uzonyi wrote:
> >>Since this thread is about optimization, I just had to chime in.
> >>On 64-bit Spur, I measured ~12.5x speedup for #getSeconds which is 
> >>impressive. It can increased further by returning the value of the first 
> >>expression.
> >>Also, I think the calculation is overcomplicated and the whole method 
> >>seems to be equivalent to:
> >>
> >>	^utcMicroseconds // 1000000 + localOffsetSeconds \\ 86400
> >
> >The implementation is simpler, but it seems to be a bit slower when I
> >measure it (DateAndTime>>asSeconds changed versus Chronology-Core-ul.21
> >on 64-bit Spur image).
> 
> I guess you meant #getSeconds not #asSeconds.
> 
> >
> >I tested with this:
> >
> > dt := DateAndTime now.
> > Time millisecondsToRun: [ 100000000 timesRepeat: [dt getSeconds ]].
> 
> That is really interesting. Do you have numbers?
> 
> Here's my benchmark:
> 
> | d |
> d := DateAndTime now.
> (1 to: 5) collect: [ :run |
> 	[ 1 to: 100000000 do: [ :i | d getSeconds ] ] timeToRun ]
> "Original ==> #(3449 3416 3430 3430 3435)"
> "Simplified ==> #(2538 2537 2566 2522 2558)"
> 
> I thought that perhaps the negative offset can affect the results, but no, 
> it's the same with -7 * 3600 as offset.

I was wrong, your simplified version *is* faster.

Here is what I get:

  "Original:"
  
  Time millisecondsToRun: [ 100000000 timesRepeat: [dt getSeconds ]].
    "==> 4207"
  
  | d |
  d := DateAndTime now.
  (1 to: 5) collect: [ :run |
          [ 1 to: 100000000 do: [ :i | d getSeconds ] ] timeToRun ]
    "==> #(3706 3726 3725 3713 3689)"
  
 "Simplified:"
  
  Time millisecondsToRun: [ 100000000 timesRepeat: [dt getSeconds ]].
    "==> 3623"
  
  | d |
  d := DateAndTime now.
  (1 to: 5) collect: [ :run |
          [ 1 to: 100000000 do: [ :i | d getSeconds ] ] timeToRun ]
    "==> #(3165 3173 3174 3173 3222)"

So your simplified version is both simpler and faster.

Please commit it to trunk :-)

Thanks,
Dave