[Cuis-dev] Strange behavior with stepping

[Juan Vuletich]

Hi Folks,

Nice catch, Gerald. On top of that, #removeFirst could have the same 
problem. I just pushed to GitHub your code, but also fixing the call to 
#removeFirst.

Hilaire, please try with the latest from GitHub. I believe Gerald is 
right, and this could fix the problem you found.

Thanks!

On 8/21/2021 10:04 AM, Gerald Klix via Cuis-dev wrote:
> Hi Hilaire,
>
> I only did a short static analysis
> (a fancy word for looking at the code
> and scratching your head).
>
> IHMO there's a race condition:
>
> WorldMorph>>#runLocalStepMethods
>
>     | stepMessage |
>     [ stepList notEmpty and:
>            [ stepList first scheduledTime <= nowTime ]]
>         whileTrue: [
>             stepMessage _ stepList first.
>
>
> This piece of code looks at the scheduleTime of the
> heap's first element then actually retrieves
> the first element.
> While this happens the heap in stepList may
> be changed by adding or removing elements.
>
> Please try the attached method and tell me if it helps.
>
> @Juan: Even if my change does not fix Hilaire's problem
> the method should still be changed.
>
>
> HTH,
>
> Gerald
>
>
> On 8/21/21 1:14 PM, Hilaire Fernandes via Cuis-dev wrote:
>> Hi,
>>
>> In DrGeo there is this user interaction to let the user easily merges 
>> two points: the user moves one point over another one to merge with, 
>> then holds for 1500 milliseconds for the merging operation to take 
>> place.
>>
>> It is done with stepping:
>>
>> restartMouseStillDownHandle         self startStepping: 
>> #processMouseStillDown             in: 1500             stepTime: 1]
>>
>> The problem is the mouseStillDown message is called immediately not 
>> after 1500 milliseconds.
>>
>> Looking at step code below, is the at: argument right? Tried with 
>> Time millisecondClockValue (as coded with Pharo), the effect is the 
>> same:
>>
>> startStepping: aSelector in: millisecs stepTime: stepTime     "Start 
>> stepping the receiver"     self world ifNotNil: [ :w |         w     
>> startStepping: self             at: Time localMillisecondClock + 
>> millisecs             selector: aSelector             stepTime: 
>> stepTime]
>>
>> Any clue?
>>
>> Thanks, best
>>
>>


-- 
Juan Vuletich
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@JuanVuletich