On Mon, Jan 25, 2021 at 12:44:53PM -0500, Taylor Blau wrote: > Thanks for including a compelling argument in favor of the approach that > I took in this patch. > > I added something along the lines of what you suggested to the final > paragraph, so now it concludes nicely instead of ending in a comma. I > briefly considered whether I should add something about how these > operations scale and how the warming efforts are really amortized across > all of the objects, but I decided against it. > > I think that this argument is already documented here, and that there's > no way to concisely state it in an already long patch. Interested > readers will easily be able to find our discussion here, which is good. That sounds good. It is sort of arguing against a strawman anyway. > > It mostly looks good to me. I agree with Junio that "compute" is a > > better verb than "load" for generating the in-memory revindex. > > Yeah, I settled on load_pack_revindex() either calling > "create_pack_revindex_in_memory()" or "load_pack_revindex_from_disk()". Perfect. > > If p->revindex_data were "const uint32_t *", then this line would just > > be: > > > > return get_be32(p->revindex_data + pos); > > > > Not a huge deal either way since the whole point is to abstract this > > behind a function where it only has to be written once. I don't think > > there is any downside from the compiler's view (and we already use this > > trick for the bitmap name-hash cache). > > Honestly, I'm not a huge fan of implicitly scaling pos by > sizeof(*p->revindex_data), but I can understand why it reads more > clearly here. I don't really feel strongly either way, so I'm happy to > change it in favor of your suggestion. > > Of course, since RIDX_HEADER_SIZE is in bytes, not uint32_t's (and it > has to be, since it's also used in the RIDX_MIN_SIZE macro, which is > compared against the st_size of stating the .rev file), you have to do > gross stuff like: > > p->revindex_data = (const uint32_t *)((const char *)p->revindex_map + RIDX_HEADER_SIZE); > > But I guess the tradeoff is worth it, since the readers are easier to > parse. Yeah, that is definitely a downside. Perhaps keeping everything in bytes makes things a bit more obvious. In which case I might suggest that revindex_data just be a "const char *". You'd have to scale any pointer computations at the point of use then, but you'd avoid needing to do any extra casting. -Peff
