[v2,0/4] Multiple subtree split fixes regarding complex repos

Commit Message

Roger Strain Oct. 11, 2018, 7:46 p.m. UTC

After doing some testing at scale, determined that one call was taking too long; replaced that with an alternate call which returns the same data significantly faster.

Also, if anyone has any other feedback on these I'd really love to hear it. It's working better for us (as in, it actually generates a compatible tree version to version) but still isn't perfect, and I'm not sure perfect is achievable, but want to make sure this doesn't things for anyone else.

Changes since v1:
Strain, Roger L (4):
  subtree: refactor split of a commit into standalone method
  subtree: make --ignore-joins pay attention to adds
  subtree: use commits before rejoins for splits
  subtree: improve decision on merges kept in split

 contrib/subtree/git-subtree.sh | 129 +++++++++++++++++++++------------
 1 file changed, 83 insertions(+), 46 deletions(-)

Comments

Junio C Hamano Oct. 12, 2018, 7:35 a.m. UTC | #1

Roger Strain <[e-mail]> writes:

> After doing some testing at scale, determined that one call was
> taking too long; replaced that with an alternate call which
> returns the same data significantly faster.

Curious where the time goes.  Do you know?

> Also, if anyone has any other feedback on these I'd really love to
> hear it. It's working better for us (as in, it actually generates

The previous one is already in 'next'; please make it incremental
with explanation as to why "show -s" is worse than "log -1" (but see
below).

>                 # processing commit without normal parent information;
>                 # fetch from repo
> -               parents=$(git show -s --pretty=%P "$rev")
> +               parents=$(git log --pretty=%P -n 1 "$rev")

If you want to learn the parents of a given commit:

	$ git help revisions

says

       <rev>^@, e.g. HEAD^@
           A suffix ^ followed by an at sign is the same as listing all parents of <rev>
           (meaning, include anything reachable from its parents, but not the commit
           itself).

so

		parents=$(git rev-parse "$rev^@")

ought to be the most efficient way to do this, I suspect.

Patch

diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh
index 1c157dbd9..7dd643998 100755
--- a/contrib/subtree/git-subtree.sh
+++ b/contrib/subtree/git-subtree.sh
@@ -633,7 +633,7 @@  process_split_commit () {
        else
                # processing commit without normal parent information;
                # fetch from repo
-               parents=$(git show -s --pretty=%P "$rev")
+               parents=$(git log --pretty=%P -n 1 "$rev")
                extracount=$(($extracount + 1))
        fi