Re: GUILE 2/3 and string encoding cost

[David Kastrup]

David Kastrup <address@hidden> writes:

> Han-Wen Nienhuys <address@hidden> writes:
>
>> On Fri, Jan 24, 2020 at 12:45 PM David Kastrup <address@hidden> wrote:
>>> >> No.  Since much of LilyPond's data containing SCM values is stored in
>>> >> STL containers, it would require serious messing with allocators to get
>>> >> there.
>>> >
>>> > Good point! And I'd agree with you, but if I look at the source code,
>>> > I can't find much STL structures that really do this. There is
>>> > Grob_array that would have to be revised, and there is a couple of
>>> > Drul_array<SCM> instances.
>>>
>>> There are a few other structures I think.  Basically one would need to
>>> go through all mark_smob routines and check for loops over arrays or
>>> other indirections.  You are right that their number seems reasonably
>>> small.
>>
>> We should be able to short circuit all of this by doing
>>
>> +#if GUILEV2
>> +
>> +void *
>> +operator new(std::size_t size) {
>> +  return scm_gc_malloc(size, "c++ new");
>> +}
>> +
>> +void
>> +operator delete(void *p) {
>> +  return scm_gc_free(p, 0, "new");
>> +}
>> +
>> +#endif
>
> I wouldn't do that since it would affect all allocated memory even
> outside of LilyPond proper, like for STL bookkeeping and file buffers
> and whatnot.

And particularly calling scm_gc_malloc before Guile has even been
started up might be problematic...

>> unfortunately, it crashes somewhere near the start of GUILE initialization.
>>
>> (in GUILE2 the above functions directly call GC_MALLOC, GC_FREE, so I
>> don't understand why this would be a problem.)
>>
>> I am actually quite attracted to moving to GUILE 2 and using BGC.
>> Debugging GC problems (eg. a constructor triggering GC, which then
>> deletes the smob under construction) were one of most hairy things to
>> get right.
>
> Them not being done right is the reason for the existence of the
> Pre_init class...

-- 
David Kastrup