Re: [PATCH 5/5] streaming.c: move {open,close,read} from vtable to "struct git_istream"

On Wed, May 05, 2021 at 02:33:32PM +0200, Ævar Arnfjörð Bjarmason wrote:

Move the definition of the structure around the open/close/read
functions introduced in 46bf043807c (streaming: a new API to read from
the object store, 2011-05-11) to instead populate "close" and "read"
members in the "struct git_istream".

This gets us rid of an extra pointer deference, and I think makes more
sense. The "close" and "read" functions are the primary interface to
the stream itself.

Let's also populate a "open" callback in the same struct. That's now
used by open_istream() after istream_source() decides what "open"
function should be used. This isn't needed to get rid of the
"stream_vtbl" variables, but makes sense for consistency.

Yeah, I think if we are going to get rid of the open vtable in an earlier
patch, it makes sense to go all the way here and make things consistent.

If we had a bunch of these objects, having the layer of indirection to
the vtable would save us some per-object memory. But we really only ever
have one of these open at a time.

-Peff