Commit 348d4f2f authored by Jeff King's avatar Jeff King Committed by Junio C Hamano

filter-branch: skip index read/write when possible

If the user specifies an index filter but not a tree filter,
filter-branch cleverly avoids checking out the tree
entirely. But we don't do the next level of optimization: if
you have no index or tree filter, we do not need to read the
index at all.

This can greatly speed up cases where we are only changing
the commit objects (e.g., cementing a graft into place).
Here are numbers from the newly-added perf test:

  Test                  HEAD^              HEAD
  ---------------------------------------------------------------
  7000.2: noop filter   13.81(4.95+0.83)   5.43(0.42+0.43) -60.7%
Signed-off-by: default avatarJeff King <peff@peff.net>
Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
parent f34be46e
......@@ -306,6 +306,15 @@ then
start_timestamp=$(date '+%s')
fi
if test -n "$filter_index" ||
test -n "$filter_tree" ||
test -n "$filter_subdir"
then
need_index=t
else
need_index=
fi
while read commit parents; do
git_filter_branch__commit_count=$(($git_filter_branch__commit_count+1))
......@@ -313,7 +322,10 @@ while read commit parents; do
case "$filter_subdir" in
"")
GIT_ALLOW_NULL_SHA1=1 git read-tree -i -m $commit
if test -n "$need_index"
then
GIT_ALLOW_NULL_SHA1=1 git read-tree -i -m $commit
fi
;;
*)
# The commit may not have the subdirectory at all
......@@ -387,8 +399,15 @@ while read commit parents; do
} <../commit |
eval "$filter_msg" > ../message ||
die "msg filter failed: $filter_msg"
if test -n "$need_index"
then
tree=$(git write-tree)
else
tree="$commit^{tree}"
fi
workdir=$workdir @SHELL_PATH@ -c "$filter_commit" "git commit-tree" \
$(git write-tree) $parentstr < ../message > ../map/$commit ||
"$tree" $parentstr < ../message > ../map/$commit ||
die "could not write rewritten commit"
done <../revs
......
#!/bin/sh
test_description='performance of filter-branch'
. ./perf-lib.sh
test_perf_default_repo
test_checkout_worktree
test_expect_success 'mark bases for tests' '
git tag -f tip &&
git tag -f base HEAD~100
'
test_perf 'noop filter' '
git checkout --detach tip &&
git filter-branch -f base..HEAD
'
test_done
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