From: Elijah Newren <newren@xxxxxxxxx>
The basename comparison optimization implemented in
find_basename_matches() is very beneficial since it allows a source to
sometimes only be compared with one other file instead of N other files.
When a match is found, both a source and destination can be removed from
the matrix of inexact rename comparisons. In contrast, the irrelevant
source optimization only allows us to remove a source from the matrix of
inexact rename comparisons...but it has the advantage of allowing a
source file to not even be loaded into memory at all and be compared to
0 other files. Generally, not even comparing is a bigger performance
win, so when both optimizations could apply, prefer to use the
irrelevant-source optimization.
For the testcases mentioned in commit 557ac0350d ("merge-ort: begin
performance work; instrument with trace2_region_* calls", 2020-10-28),
this change improves the performance as follows:
Before After
no-renames: 5.708 s ± 0.111 s 5.680 s ± 0.096 s
mega-renames: 102.171 s ± 0.440 s 13.812 s ± 0.162 s
just-one-mega: 3.471 s ± 0.015 s 506.0 ms ± 3.9 ms
Signed-off-by: Elijah Newren <newren@xxxxxxxxx>
---
diffcore-rename.c | 37 +++++++++++++++++++++++++++++++++----
1 file changed, 33 insertions(+), 4 deletions(-)
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 7f6115fd9018..e8508541be14 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -527,6 +527,7 @@ static void update_dir_rename_counts(struct dir_rename_info *info,
}
static void initialize_dir_rename_info(struct dir_rename_info *info,
+ struct strset *relevant_sources,
struct strset *dirs_removed,
struct strmap *dir_rename_count)
{
@@ -534,7 +535,7 @@ static void initialize_dir_rename_info(struct dir_rename_info *info,
struct strmap_entry *entry;
int i;
- if (!dirs_removed) {
+ if (!dirs_removed && !relevant_sources) {
info->setup = 0;
return;
}
@@ -549,7 +550,20 @@ static void initialize_dir_rename_info(struct dir_rename_info *info,
strmap_init_with_options(&info->dir_rename_guess, NULL, 0);
/* Setup info->relevant_source_dirs */
- info->relevant_source_dirs = dirs_removed;
+ info->relevant_source_dirs = NULL;
+ if (dirs_removed || !relevant_sources) {
+ info->relevant_source_dirs = dirs_removed; /* might be NULL */
+ } else {
+ info->relevant_source_dirs = xmalloc(sizeof(struct strintmap));
+ strset_init(info->relevant_source_dirs);
+ strset_for_each_entry(relevant_sources, &iter, entry) {
+ char *dirname = get_dirname(entry->key);
+ if (!dirs_removed ||
+ strset_contains(dirs_removed, dirname))
+ strset_add(info->relevant_source_dirs, dirname);
+ free(dirname);
+ }
+ }
/*
* Loop setting up both info->idx_map, and doing setup of
@@ -627,6 +641,13 @@ static void cleanup_dir_rename_info(struct dir_rename_info *info,
/* dir_rename_guess */
strmap_clear(&info->dir_rename_guess, 1);
+ /* relevant_source_dirs */
+ if (info->relevant_source_dirs &&
+ info->relevant_source_dirs != dirs_removed) {
+ strset_clear(info->relevant_source_dirs);
+ FREE_AND_NULL(info->relevant_source_dirs);
+ }
+
/* dir_rename_count */
if (!keep_dir_rename_count) {
partial_clear_dir_rename_count(info->dir_rename_count);
@@ -749,6 +770,7 @@ static int idx_possible_rename(char *filename, struct dir_rename_info *info)
static int find_basename_matches(struct diff_options *options,
int minimum_score,
struct dir_rename_info *info,
+ struct strset *relevant_sources,
struct strset *dirs_removed)
{
/*
@@ -839,6 +861,11 @@ static int find_basename_matches(struct diff_options *options,
intptr_t src_index;
intptr_t dst_index;
+ /* Skip irrelevant sources */
+ if (relevant_sources &&
+ !strset_contains(relevant_sources, filename))
+ continue;
+
/*
* If the basename is unique among remaining sources, then
* src_index will equal 'i' and we can attempt to match it
@@ -1164,7 +1191,7 @@ void diffcore_rename_extended(struct diff_options *options,
/* Preparation for basename-driven matching. */
trace2_region_enter("diff", "dir rename setup", options->repo);
- initialize_dir_rename_info(&info,
+ initialize_dir_rename_info(&info, relevant_sources,
dirs_removed, dir_rename_count);
trace2_region_leave("diff", "dir rename setup", options->repo);
@@ -1172,7 +1199,9 @@ void diffcore_rename_extended(struct diff_options *options,
trace2_region_enter("diff", "basename matches", options->repo);
rename_count += find_basename_matches(options,
min_basename_score,
- &info, dirs_removed);
+ &info,
+ relevant_sources,
+ dirs_removed);
trace2_region_leave("diff", "basename matches", options->repo);
/*
--
gitgitgadget
