> On Jul 15, 2020, at 4:35 PM, Eric Wong <[email protected]> wrote:
>
> [email protected] wrote:
>> Right, that makes sense. I really need to document this (and
>> I apologize for not doing so already), but
>> `rb_gc_register_address` will pin your objects. When you know
>> you're done with the reference, you can release it with
>> `rb_gc_unregister_address`. Of course if you don't call the
>> unregister function, the reference will stay alive forever.
>
> Btw, does rb_gc_register_mark_object pin? A quick glance at
> gc.c tells me it doesn't, and I'll need to revert commit
> 2a6cb76d5010cb763ef5a2c305728465d15eb7c9 in unicorn:
> https://yhbt.net/unicorn-public/[email protected]/
Yes, it does pin. I’m not super proud of this code, but here is where objects
passed to rb_gc_register_mark_object get pinned:
https://github.com/ruby/ruby/blob/c2a6295ec04a191c689d22254ac1ad5d665e27ad/vm.c#L2307-L2320
I don’t know why the mark object array is an array of arrays (I assume so as
not to waste space in the array buffer?). Maybe this could be a more friendly
data structure.
I created a pinned list in compile.c so that objects allocated and used at
compile time don’t move (they become free to move once iseq assembly is
finished). It seems that might be a more generally useful thing, but so far
I’ve only seen two places that need this feature.
