Re: [PATCH 2/2] refs.c: Write reflogs for notes just like for branch heads

On Mon, Mar 29, 2010 at 04:25:22PM +0200, Johan Herland wrote:

quoted

This is actually inspired by Jeff's novel notes use. I think there
are use cases where a notes log makes sense (notes on commits) and
those where it does not (metadata/textconv). In both cases having a
reflog is useful. So, the next step is really to allow notes trees
without history, which also takes care of the pruning issue. I know
how to do this, I just have to decide about the configuration
options.

I noticed that Jeff's proof-of-concept wrote notes trees without making 
notes commits, and although it seemed like a bug at first, it does - as 
you say - provide a rather nice way to store notes trees without 
history.

No, it was very much intentional.

However, I think the next iteration will wrap the tree in an actual
commit, but just keep each commit parentless. That will provide a nice
spot for metadata like the cache validity information.

I like the idea of having a reflog, just because you could use it to
salvage an old cache if you were playing around with your helper's
options (or debugging your helper :) ). The usual 90-day expiration
time is perhaps too long, though.

Note that I haven't explicitly designed the notes feature with this in 
mind, so it's wise to add testcases for expected behaviour once we 
start use history-less notes trees.

Thinking about it, the notes code itself (notes.h/.c) only wants a notes 
_tree_ object, so will probably work fine with history-less notes 
trees. But builtin/notes.c with its public commit_notes() function may 
be another story...

I was planning on using my own cache-specific helper instead of
commit_notes() anyway, so that shouldn't be a problem. By using a commit
wrapper, I don't think any of the display code should be confused (since
they need to handle the case of a root note commit anyway). Once I have
some example trees, I can poke at them with the existing notes code and
see how they behave (and how we _want_ them to behave, since I'm not
sure yet what sort of cache introspection, if any, would be useful).

-Peff