Re: [PATCH v2 2/3] fast-export: improve speed by skipping blobs

On Mon, May 6, 2013 at 11:20 AM, Jeff King [off-list ref] wrote:

On Mon, May 06, 2013 at 08:08:45AM -0700, Junio C Hamano wrote:

quoted

quoted

I'm also not sure why your claim "we don't care about blobs" is true,
because naively we would want future runs of fast-export to avoid having
to write out the whole blob content when mentioning the blob again.

The existing documentation is fairly clear that marks for objects
other than commits are not exported, and the import-marks codepath
discards anything but commits, so there is no mechanism for the
existing fast-export users to leave blob marks in the marks file for
later runs of fast-export to take advantage of.  The second
invocation cannot refer to such a blob in the first place.

OK. If the argument is "we do not write them, so do not bother reading
them back in", I think that is reasonable.

We already do that:

5d3698f fast-export: avoid importing blob marks

It could hurt anybody trying
to run "fast-export" against a marks file created by somebody else, but
that is also the same case that is being helped here (since otherwise,
we would not be seeing blob entries at all).

I do not offhand know enough about the internals of import/export-style
remote-helpers to say whether the "hurt" case even exists, let alone how
common it is.

quoted

By discarding marks on blobs, we may be robbing some optimization
possibilities, and by discarding marks on tags, we may be robbing
some features, from users of fast-export; we might want to add an
option "--use-object-marks={blob,commit,tag}" or something to both
fast-export and fast-import, so that the former can optionally write
marks for non-commits out, and the latter can omit non commit marks
if the user do not need them. But that is a separate issue.

Yeah, that would allow the old behavior (and more) if anybody is hurt by
this.

There is no behavior change in this patch. We do *exactly* the same as before.

-- 
Felipe Contreras