Re: What is an efficient way to get all blobs / trees that have notes attached?

From: Johan Herland <johan@herland.net>
Date: Apr 1, 2016, 12:16 UTC
Message-ID: <CALKQrgdytYJtMTBHXbcRQ_iT5rWakZCxxqRW1rpLsPiSejud-Q@mail.gmail.com>
In-Reply-To: <ndljs8$vj3$1@ger.gmane.org>

On Fri, Apr 1, 2016 at 12:51 PM, Sebastian Schuberth <sschuberth@gmail.com> wrote:

Show 15 quoted lines

> Hi,
>
> I'm curious whether there's a more efficient way to get a list of blobs /
> trees (and their names) that have notes attached than doing this:
>
> 1) Get all notes refs I'm interested in (git-for-each-ref).
>
> 2) For each notes ref, get the list of notes (git-notes list) and store them
> in a hash table that maps object hashes to notes.
>
> 3) Recursively list all blobs / trees (git-ls-tree) and look whether an
> object's hash is conatined in our table to get its notes.
>
> In particular 3) could be expensive for repos with a lot of files as we're
> looking at all of them just to see whether they have notes attached.

In (3), why would you need to search through _all_ blobs/trees? Would it not be cheaper to simply query the object type of each annotated object from (2)? I.e. something like:

for notes_ref in $(git for-each-ref refs/notes | cut -c 49-)
do
    echo "--- $notes_ref ---"
    for annotated_obj in $(git notes --ref=$notes_ref list | cut -c 41-)
    do
        type=$(git cat-file -t "$annotated_obj")
        if test "$type" != "commit"
        then
            echo "$annotated_obj: $type"
        fi
    done
done

Can probably be made even faster by using the --batch option to cat-file...

...Johan

-- 
Johan Herland, <johan@herland.net>
www.herland.net