Re: filter-branch IO optimization

Hi folks,

now finally managed the index-filter part. The main problem, IIRC, was that git-update-index didn't automatically create an empty index, so I needed to explicitly copy in (manually created it with an empty repo).

My current filter code is:

if [ ! "$GIT_AUTHOR_EMAIL" ] && [ ! "$GIT_COMMITTER_EMAIL" ]; then
	export GIT_AUTHOR_EMAIL="nobody@none.org"
	export GIT_COMMITTER_NAME="nobody@none.org"
elif [ ! "$GIT_AUTHOR_EMAIL" ]; then
	export GIT_AUTHOR_EMAIL="$GIT_COMMITTER_EMAIL"
elif [ ! "$GIT_COMITTER_EMAIL" ]; then
	export GIT_COMMITTER_EMAIL="$GIT_AUTHOR_NAME"
fi

if [ ! "$GIT_AUTHOR_NAME" ] && [ ! "$GIT_COMMITTER_NAME" ]; then
	export GIT_AUTHOR_NAME="nobody@none.org"
	export GIT_COMMITTER_NAME="nobody@none.org"
elif [ ! "$GIT_AUTHOR_NAME" ]; then
	export GIT_AUTHOR_NAME="$GIT_COMMITTER_NAME"
elif [ ! "$GIT_COMITTER_NAME" ]; then
	export GIT_COMMITTER_NAME="$GIT_AUTHOR_NAME"
fi

cp ../../../../scripts/index.empty $GIT_INDEX_FILE.new

git ls-files -s |
    sed "s-\t\"*-&addons/-" |
    grep -e "\t*addons/$module" |
    ( export GIT_INDEX_FILE=$GIT_INDEX_FILE.new ; git update-index --index-info )

mv $GIT_INDEX_FILE.new $GIT_INDEX_FILE

Now another problem: this leaves behind thousands of now empty merge nodes (--prune-empty doesnt seem to catch them all), so I loop through additional `git filter-branch --prune-empty` runs, until the ref remains unchanged.

This process is even more time-consuming, as it takes really many passes (havent counted them yet).

Does anyone have an idea, why a single run doesnt catch that all?

cu