Re: [PATCH v4 2/2] diff: don't read index when --no-index is given
From: Junio C Hamano <hidden>
Date: 2016-06-15 22:59:27
Thomas Gummerer [off-list ref] writes:
git diff --no-index ... currently reads the index, during setup, when calling gitmodules_config(). This results in worse performance when the index is not actually needed. This patch avoids calling gitmodules_config() when the --no-index option is given. The times for executing "git diff --no-index" in the WebKit repository are improved as follows: Test HEAD~3 HEAD ------------------------------------------------------------------ 4001.1: diff --no-index 0.24(0.15+0.09) 0.01(0.00+0.00) -95.8% An additional improvement of this patch is that "git diff --no-index" no longer breaks when the index file is corrupt, which makes it possible to use it for investigating the broken repository. To improve the possible usage as investigation tool for broken repositories, setup_git_directory_gently() is also not called when the --no-index option is given. Also add a test to guard against future breakages, and a performance test to show the improvements. Signed-off-by: Thomas Gummerer <redacted> ---
Looks reasonable. Thanks. Will queue.
quoted hunk
builtin/diff.c | 7 +++++-- t/perf/p4001-diff-no-index.sh | 22 ++++++++++++++++++++++ t/t4053-diff-no-index.sh | 15 +++++++++++++++ 3 files changed, 42 insertions(+), 2 deletions(-) create mode 100755 t/perf/p4001-diff-no-index.shdiff --git a/builtin/diff.c b/builtin/diff.c index da69e4a..ea1dd65 100644 --- a/builtin/diff.c +++ b/builtin/diff.c@@ -298,7 +298,9 @@ int cmd_diff(int argc, const char **argv, const char *prefix) break; } - prefix = setup_git_directory_gently(&nongit); + if (!no_index) + prefix = setup_git_directory_gently(&nongit); + /* * Treat git diff with at least one path outside of the * repo the same as if the command would have been executed@@ -311,7 +313,8 @@ int cmd_diff(int argc, const char **argv, const char *prefix) !path_inside_repo(prefix, argv[i + 1])))) no_index = DIFF_NO_INDEX_IMPLICIT; - gitmodules_config(); + if (!no_index) + gitmodules_config(); git_config(git_diff_ui_config, NULL); init_revisions(&rev, prefix);diff --git a/t/perf/p4001-diff-no-index.sh b/t/perf/p4001-diff-no-index.sh new file mode 100755 index 0000000..683be69 --- /dev/null +++ b/t/perf/p4001-diff-no-index.sh@@ -0,0 +1,22 @@ +#!/bin/sh + +test_description="Test diff --no-index performance" + +. ./perf-lib.sh + +test_perf_large_repo +test_checkout_worktree + +file1=$(git ls-files | tail -n 2 | head -1) +file2=$(git ls-files | tail -n 1 | head -1) + +test_expect_success "empty files, so they take no time to diff" " + echo >$file1 && + echo >$file2 +" + +test_perf "diff --no-index" " + git diff --no-index $file1 $file2 >/dev/null +" + +test_donediff --git a/t/t4053-diff-no-index.sh b/t/t4053-diff-no-index.sh index 979e983..077c775 100755 --- a/t/t4053-diff-no-index.sh +++ b/t/t4053-diff-no-index.sh@@ -29,4 +29,19 @@ test_expect_success 'git diff --no-index relative path outside repo' ' ) ' +test_expect_success 'git diff --no-index with broken index' ' + ( + cd repo && + echo broken >.git/index && + git diff --no-index a ../non/git/a + ) +' + +test_expect_success 'git diff outside repo with broken index' ' + ( + cd repo && + git diff ../non/git/a ../non/git/b + ) +' + test_done