Re: Rewrite Mutable_properties based on vector<SCM> (issue 575990043 by address@hidden)

[hanwenn]

On 2020/04/13 20:26:10, dak wrote:
> On 2020/04/13 20:21:29, dak wrote:
> 
> >
>
https://codereview.appspot.com/575990043/diff/577740043/lily/mutable-properties.cc#newcode109
> > lily/mutable-properties.cc:109: Mutable_properties::mark () const
> > This can segfault in GUILEv2 and/or depending on some other
circumstances
> since
> > the C++ members are only getting initialized after the GC hook is
already
> > operative.
> > 
> > You need to sort the C++ structures potentially accessed by the GC
hook into a
> > Preinit class (grep for Preinit for existing uses) and inherit from
that
> before
> > inheriting from whatever operates the Smob.  Then C++ guarantees an
> > initialisation order consistent with GC hook operation.
> 
> Actually, a less involved implementation where the value cell is SCM
is to just
> use a Scheme vector.  That also significantly speeds up garbage
collection
> relying on mark hooks because then only a single scm_gc_mark call is
made and
> Guile does the rest internally.

I actually wanted to start that working on that, but I was happy with
the numbers. 
Now that the numbers turned out to be bogus, I want to dig in deeper
into 
measurements. I want to run lilypond through cachegrind to understand
better what is 
happening. In my mind, this code should be strictly better than the
alist-based solution,
but that is not borne out by timing.




https://codereview.appspot.com/575990043/