Question to GC experts: NO_SCAN for a part of the block

[Stanislav Blinov via Digitalmars-d]

On Tuesday, 6 June 2017 at 12:07:28 UTC, Steven Schveighoffer 
wrote:
> On 6/6/17 6:36 AM, Stanislav Blinov wrote:
>> On Tuesday, 6 June 2017 at 09:57:31 UTC, Steven Schveighoffer 
>> wrote:
>>
>>> No, 2 allocations instead of N.
>>
>> Oh, I misunderstood you. You mean two blocks total, for 
>> scanned and
>> non-scanned data. This could indeed work for cases when more 
>> than two
>> arrays are needed. Still, it's one extra allocation.
>>
>
> True. But O(2) is better than O(N) :)
>
> -Steve

Heh, this isn't malloc. We could end up in a situation when even 
one allocation is slower than N, depending on when they happen :)

Actually, separate blocks might be a decent choice: there's 
another problem with sharing blocks for different data in that 
finalizers can't be run. So such a function would either not 
support types with finalizers at all, or would have to allocate 
separate blocks for such types anyway. Don't know, need to 
actually implement and measure if it's even worth the trouble.