On Mon, Jun 12, 2017 at 12:52:54PM -0700, Jonathan Tan wrote: > > I like the idea of consolidating the logic. But I can't help but feel > > that pulling these fields out of object_info is a step backwards. The > > point of that struct is to let the caller specify which aspects of the > > object they're interested in > > My issue was that there are some parts that cannot be turned off (in > particular, the object_info.u.packed part). Having said that, reading > the packed object itself should give us enough information to populate > that, so I'll take a look and see if this is possible.
I think in general that the parts of object_info which aren't optional should be largely "free" to set (or at least O(1)). > > Another approach to this whole mess is to have a single function for > > acquiring a "handle" to an object, along with functions to query aspects > [...] > > There are a few safeguards that, I think, only work with the current > get-everything-then-forget-about-it approach (the packed-loose-packed > retry mechanism, and the desperate retry-if-corrupt-packed-object one). > If we have a handle with a cache, then, for example, we would lose the > ability to retry packed after loose if the handle has already declared > that the object is loose. Yes, the handle would have to make some guarantee that it could access the object. Which would generally involve holding open a descriptor or mmap. That would probably take some surgery to make it work with the way pack mmap windows work. So the whole "handle" thing is how it probably _ought_ to work, but I agree we may be too far down the other path to make it worth switching. -Peff
