Re: [PATCH v2 11/11] vcs-svn,svn-fe: add an option to write svnrev notes

Sorry for a way too slow response. This patch is probably the most
unbaked one, so I'll start here.

On Tue, Jul 26, 2011 at 3:39 AM, Jonathan Nieder [off-list ref] wrote:

Hi,

Dmitry Ivankov wrote:

quoted

There are already a few options to determine svn revision from which
a git commit imported with svn-fe came from. One is to make svn-fe
write a git-svn-id: line to commit messages. Another one is to calc
distance to the root commit. The former includes a "url" and is for
git-svn compatibility, the latter is obviously slow and a bit fragile.

$ svn-fe --notes_ref=notes_tree --ref=branch...
will write annotations for branch commits to the notes_tree, each
annotation is a simple "rN" string. Then these annotations can be
viewed manually or used in incremental import to detect the last
imported revision or to (re)create the import marks for further
imports.

Wouldn't another way be to look at the mark numbers?

If marks file is absent (after clone for example), we'll need to look
at notes anyway.
If it is present and has a mark for latest revision we can hope it is
valid and not
regenerate it.
If for some reason notes are lost and marks are present, it's possible
to recreate
notes from marks though, at least "rN" ones.

I am not sure I like this.  svn-fe is supposed to be a generally
useful tool, and this patch hard-codes the particular note format rN.
If it is needed, maybe it would be possible to do something like

       --notes-ref=refs/notes/svn-rev --note='project foo, r%N'

As a bonus, that would allow including more information using
different flag characters in the note in the future.

Format string looks nice. While the whole notes thing may need
more thinking.
The main reason I wrote these in svn-fe is that it's more atomic
to write note just after writing a commit. Also "checkpoint" will
create notes for current status (and will write marks too, but weren't
we going to consider notes as a primary data copy? it can be cloned
for example).

One more consideration is that copy-from information most likely
will be written by svn-fe (nothing else knows it anyway) to some
notes, so we'll need some notes writing in svn-fe.