Re: MPS: weak hash tables

[Gerd Möllmann]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Gerd Möllmann <gerd.moellmann@gmail.com>
>> Cc: pipcet@protonmail.com,  eller.helmut@gmail.com,  yantar92@posteo.net,
>>   emacs-devel@gnu.org
>> Date: Sun, 07 Jul 2024 19:08:45 +0200
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> > But does igc know that an interval is no longer needed?  How does it
>> > know that when sweep_intervals in the old GC needed to do that
>> > explicitly in C?
>> 
>> It's kind of mark-sweep vs. copying collector algorithms.
>> 
>> The mark phase of mark-sweep marks all objects reachable from roots,
>> then the sweep phase frees what's not marked.
>> 
>> A copying collector copies every object reachable from roots. At the
>> end, what has not been copied is implicitly unreachable.
>> 
>> MPS is a copying collection, with some additional complications, like
>> ambiguous references (-> mostly-copying), and incrementality (->
>> barriers), but the principle is still the same.
>
> I understand all that, but unchaining an interval involves the need to
> modify the pointers of its adjacent nodes, and how can MPS do that
> without understanding our data structures?

Can you please show me what code you mean?