> On 08 May 2015, at 2:12 , Mariano Martinez Peck <marianop...@gmail.com> wrote: > > > > On Fri, May 8, 2015 at 9:00 AM, Henrik Johansen <henrik.s.johan...@veloxit.no > <mailto:henrik.s.johan...@veloxit.no>> wrote: > Hi Esteban! > As we talked about on IRC yesterday, I had hoped to employ the fast become > discussed in > http://forum.world.st/Igor-s-fast-become-for-CompiledMethods-in-Cog-td4345568.html > > <http://forum.world.st/Igor-s-fast-become-for-CompiledMethods-in-Cog-td4345568.html> > to bring faster proxy loading untill Spur arrives. > Sadly, it's not present in any current VM's, for reasons unknown*. > > Luckily, the alternative proposed by Levente in the original thread > (http://forum.world.st/A-trick-to-speedup-become-but-not-becomeForward-tp3707064p3708128.html > > <http://forum.world.st/A-trick-to-speedup-become-but-not-becomeForward-tp3707064p3708128.html>) > is appropriate for our case. > As I don't have write-access to Voyage repo, I've attached the package with > the changes (which work in both 3.0 and 4.0, but I assume not older, due to > using the SlotBuilder for anon subclasses) > > > hahahahah excellent. It was similar to the same idea I have for my proxies in > Marea. In my case, what I did is to have 3 types of Proxies (each with each > different object "format" -> normal, compact, long), and each of those proxy > classes was a "variableSubclass". So then when I received the object to > proxify, I would create an instance (the correct one from one of those 3 > proxy classes) of the size of the object to proxify. Therefore, both, the > proxy and the target would have same size and format, and therefore I could > simply apply Igor idea.
Yeah, it's a really nice fast-path, when the VM's become implementation usually involves a heap scan... In the case of Voyage, we're restricted in that we don't start out with a database ID, and not the actual original object, so perfectly pre-shaping the proxy is impossible. Variably sized objects are right out, so I settled on the compromise that was easy to do; fixed size objects with equal or greater number of instvars as the proxy class. To do fast swapping with objects of less than 3 slots, the current data held in proxy slots would have to be held somewhere external, which is doable, but ugly. (You can also work around this easily if the performance hit is noticeable by adding dummy slots...) Compact proxies is a really limited use case, since you never store any of the builtin ones in buckets directly, you'd have to manually make your mapped classes compact. Seeing as how it's really just a holdover performance hack till Spur is ready for use and become: becomes fast, I don't think it makes sense implementing either in the context of Voyage. Cheers, Henry
