Re: Understanding version 4 packs

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mar 25, 2007, 17:09 UTC
Message-ID: <Pine.LNX.4.64.0703251004580.6730@woody.linux-foundation.org>
In-Reply-To: <20070325091806.GH25863@spearce.org>

On Sun, 25 Mar 2007, Shawn O. Pearce wrote:

Show 8 quoted lines

> >
> > What happens to the paths, that do not have a correponding entry in the
> > path name table, because they are not among the 65535 most frequent
> > paths in the pack?
> 
> They don't appear in the table.  And any tree that uses them is
> forced to use the "legacy" OBJ_TREE encoding.  Which is what we
> have now in pack v2, and in loose objects.

Would it hurt too much to just make it four bytes, and avoid that issue?

Special cases - and *especially* special cases that are hard to trigger in the first place - equal bugs. And bugs are much much worse than trying to save a little bit of space.

> The author_time field is not present if flags & 128 is true.
> If flags & 128 is false, its present, and uses the same encoding
> as commit_time.  Why is this field optional?  Because its not
> uncommon for it to match commit_time!  ;-)

If the author time is the same as the commit time, most of the time the author is the same as the committer too, no? So the field should be conditional not for the author_time, but for the combination, no?

Our email-parsing tools (which is the most common reason for a committer not being the same as the author) all take the author date from the email. So I don't think author_time == committer_time except when the committer and the author are one and the same person.

			Linus