Though I have tried to attack it with some tricky combinations, I did
not found a problem with current implementation.
It was funny to see how nil is handled as any other object in WeakSet
fixCollisionsFrom: (scanFor: nil works).

However, it's a pity not to recycle all those nils until next grow!
Here comes a little trial for recycling reclaimed nil slots in Pharo
(seems compatible with 3.10.2).
No guarantee... Note there is no WeakSet tests in Pharo nor 3.10.2 currently :(

Nicolas

2009/5/6 Andreas Raab <andreas.raab at gmx.de>:
> Nicolas Cellier wrote:
>>
>> Take this example:
>
> Ah, good point. (it works fine with o1 = 'g' and o2 = o3 = o4 = 'd'). The
> thing is that the test in WeakSet>>add: was misleading - it tests for nil
> where scanFor: searches only for flag.
>
> Cheers,
>  - Andreas
>
>> ws := WeakSet new.
>> array := WeakSet new instVarAt: (WeakSet allInstVarNames indexOf:
>> 'array').
>> o1 hash \\ array size + 1 -> 1.
>> o2 hash \\ array size + 1 -> 2.
>> o3 hash \\ array size + 1 -> 1.
>> ws add: o1; add: o2; add: o3.
>>
>> o1 := o2 := nil.
>> Smalltalk garbageCollect.
>> "o1 and o2 are reclaimed."
>> (array at: 1) -> nil.
>> (array at: 2) -> nil.
>>
>> o4 hash \\ array size + 1 -> 1.
>> ws add o4.
>> (array at: 1) -> o4.
>>
>> (ws includes: o3) -> false.
>>
>> I will try and build a test case. Should be easy with Fractions.
>>
>> 2009/5/6 Andreas Raab <andreas.raab at gmx.de>:
>>>
>>> Nicolas Cellier wrote:
>>>>
>>>> Isn't that dangerous if you don't fixCollisionsFrom: index ?
>>>
>>> Why would it? All this does is avoiding to update the tally ivar if we're
>>> replacing a previously reclaimed entry with a new value. And I don't
>>> think
>>> that #fixCollisionsFrom: even looks at tally.
>>>
>>> Cheers,
>>>  - Andreas
>>>
>>>> Nicolas
>>>>
>>>> 2009/5/6 Andreas Raab <andreas.raab at gmx.de>:
>>>>>
>>>>> Adrian Lienhard wrote:
>>>>>>
>>>>>> I haven't had time to look into this very closely yet but maybe
>>>>>> somebody
>>>>>> else already knows what is going on. My guess is that the NewSymbols
>>>>>> weak
>>>>>> set is repeatedly grown since tally is not decreased if the GC removes
>>>>>> a
>>>>>> weak element.
>>>>>
>>>>> That's an excellent guess. Try changing WeakSet to e.g.,
>>>>>
>>>>> WeakSet>>atNewIndex: index put: aValue
>>>>>  "Add newValue at the given index. Don't increment tally
>>>>>   if current slot is nil since a previous value has been collected"
>>>>>  (array at: index) ifNil:[^array at: index put: aValue].
>>>>>  ^super atNewIndex: index put: aValue
>>>>>
>>>>> Cheers,
>>>>>  - Andreas
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>>
>>
>
>
>
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