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diffcore-rename: avoid doing basename comparisons for irrelevant sources
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@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
parent
f89b4f2bee
commit
e4fd06e7e2
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@ -527,6 +527,7 @@ static void update_dir_rename_counts(struct dir_rename_info *info,
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}
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static void initialize_dir_rename_info(struct dir_rename_info *info,
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struct strset *relevant_sources,
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struct strset *dirs_removed,
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struct strmap *dir_rename_count)
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{
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@ -534,7 +535,7 @@ static void initialize_dir_rename_info(struct dir_rename_info *info,
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struct strmap_entry *entry;
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int i;
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if (!dirs_removed) {
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if (!dirs_removed && !relevant_sources) {
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info->setup = 0;
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return;
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}
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@ -549,7 +550,20 @@ static void initialize_dir_rename_info(struct dir_rename_info *info,
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strmap_init_with_options(&info->dir_rename_guess, NULL, 0);
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/* Setup info->relevant_source_dirs */
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info->relevant_source_dirs = dirs_removed;
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info->relevant_source_dirs = NULL;
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if (dirs_removed || !relevant_sources) {
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info->relevant_source_dirs = dirs_removed; /* might be NULL */
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} else {
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info->relevant_source_dirs = xmalloc(sizeof(struct strintmap));
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strset_init(info->relevant_source_dirs);
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strset_for_each_entry(relevant_sources, &iter, entry) {
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char *dirname = get_dirname(entry->key);
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if (!dirs_removed ||
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strset_contains(dirs_removed, dirname))
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strset_add(info->relevant_source_dirs, dirname);
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free(dirname);
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}
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}
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/*
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* Loop setting up both info->idx_map, and doing setup of
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@ -627,6 +641,13 @@ static void cleanup_dir_rename_info(struct dir_rename_info *info,
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/* dir_rename_guess */
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strmap_clear(&info->dir_rename_guess, 1);
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/* relevant_source_dirs */
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if (info->relevant_source_dirs &&
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info->relevant_source_dirs != dirs_removed) {
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strset_clear(info->relevant_source_dirs);
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FREE_AND_NULL(info->relevant_source_dirs);
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}
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/* dir_rename_count */
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if (!keep_dir_rename_count) {
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partial_clear_dir_rename_count(info->dir_rename_count);
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@ -749,6 +770,7 @@ static int idx_possible_rename(char *filename, struct dir_rename_info *info)
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static int find_basename_matches(struct diff_options *options,
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int minimum_score,
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struct dir_rename_info *info,
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struct strset *relevant_sources,
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struct strset *dirs_removed)
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{
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/*
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@ -839,6 +861,11 @@ static int find_basename_matches(struct diff_options *options,
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intptr_t src_index;
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intptr_t dst_index;
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/* Skip irrelevant sources */
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if (relevant_sources &&
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!strset_contains(relevant_sources, filename))
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continue;
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/*
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* If the basename is unique among remaining sources, then
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* src_index will equal 'i' and we can attempt to match it
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@ -1164,7 +1191,7 @@ void diffcore_rename_extended(struct diff_options *options,
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/* Preparation for basename-driven matching. */
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trace2_region_enter("diff", "dir rename setup", options->repo);
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initialize_dir_rename_info(&info,
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initialize_dir_rename_info(&info, relevant_sources,
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dirs_removed, dir_rename_count);
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trace2_region_leave("diff", "dir rename setup", options->repo);
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@ -1172,7 +1199,9 @@ void diffcore_rename_extended(struct diff_options *options,
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trace2_region_enter("diff", "basename matches", options->repo);
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rename_count += find_basename_matches(options,
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min_basename_score,
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&info, dirs_removed);
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&info,
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relevant_sources,
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dirs_removed);
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trace2_region_leave("diff", "basename matches", options->repo);
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/*
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