From 9799889f2e2caddee00d59aec3e4ff605a275f98 Mon Sep 17 00:00:00 2001 From: Elijah Newren Date: Thu, 11 Mar 2021 00:38:24 +0000 Subject: diffcore-rename: enable filtering possible rename sources Add the ability to diffcore_rename_extended() to allow external callers to declare that they only need renames detected for a subset of source files, and use that information to skip detecting renames for them. There are two important pieces to this optimization that may not be obvious at first glance: * We do not require callers to just filter the filepairs out to remove the non-relevant sources, because exact rename detection is fast and when it finds a match it can remove both a source and a destination whereas the relevant_sources filter can only remove a source. * We need to filter out the source pairs in a preliminary pass instead of adding a strset_contains(relevant_sources, one->path) check within the nested matrix loop. The reason for that is if we have 30k renames, doing 30k * 30k = 900M strset_contains() calls becomes extraordinarily expensive and defeats the performance gains from this change; we only want to do 30k such calls instead. If callers pass NULL for relevant_sources, that is special cases to treat all sources as relevant. Since all callers currently pass NULL, this optimization does not yet have any effect. Subsequent commits will have merge-ort compute a set of relevant_sources to restrict which sources we detect renames for, and have merge-ort pass that set of relevant_sources to diffcore_rename_extended(). A note about filtering order: Some may be curious why we don't filter out irrelevant sources at the same time we filter out exact renames. While that technically could be done at this point, there are two reasons to defer it: First, was to reinforce a lesson that was too easy to forget. As I mentioned above, in the past I filtered irrelevant sources out before exact rename checking, and then discovered that exact renames' ability to remove both sources and destinations was an important consideration and thus doing the filtering after exact rename checking would speed things up. Then at some point I realized that basename matching could also remove both sources and destinations, and decided to put irrelevant source filtering after basename filtering. That slowed things down a lot. But, despite learning about this important ordering, in later restructuring I forgot and made the same mistake of putting the filtering after basename guided rename detection again. So, I have this series of patches structured to do the irrelevant filtering last to start to show how much extra it costs, and then add relevant filtering in to find_basename_matches() to show how much it speeds things up. Basically, it's a way to reinforce something that apparently was too easy to forget, and make sure the commit messages record this lesson. Second, the items in the "relevant_sources" in this patch series will include all sources that *might be* relevant. It has to be conservative and catch anything that might need a rename, but in the patch series after this one we'll find ways to weed out more of the *might be* relevant ones. Unfortunately, merge-ort does not have sufficient information to weed those ones out, and there isn't enough information at the time of filtering exact renames out to remove the extra ones either. It has to be deferred. So the deferral is in part to simplify some later additions. Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano --- diffcore-rename.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) (limited to 'diffcore-rename.c') diff --git a/diffcore-rename.c b/diffcore-rename.c index 1fe902ed2a..7f6115fd90 100644 --- a/diffcore-rename.c +++ b/diffcore-rename.c @@ -991,11 +991,12 @@ static int find_renames(struct diff_score *mx, return count; } -static void remove_unneeded_paths_from_src(int detecting_copies) +static void remove_unneeded_paths_from_src(int detecting_copies, + struct strset *interesting) { int i, new_num_src; - if (detecting_copies) + if (detecting_copies && !interesting) return; /* nothing to remove */ if (break_idx) return; /* culling incompatible with break detection */ @@ -1022,12 +1023,18 @@ static void remove_unneeded_paths_from_src(int detecting_copies) * from rename_src here. */ for (i = 0, new_num_src = 0; i < rename_src_nr; i++) { + struct diff_filespec *one = rename_src[i].p->one; + /* * renames are stored in rename_dst, so if a rename has * already been detected using this source, we can just * remove the source knowing rename_dst has its info. */ - if (rename_src[i].p->one->rename_used) + if (!detecting_copies && one->rename_used) + continue; + + /* If we don't care about the source path, skip it */ + if (interesting && !strset_contains(interesting, one->path)) continue; if (new_num_src < i) @@ -1040,6 +1047,7 @@ static void remove_unneeded_paths_from_src(int detecting_copies) } void diffcore_rename_extended(struct diff_options *options, + struct strset *relevant_sources, struct strset *dirs_removed, struct strmap *dir_rename_count) { @@ -1060,6 +1068,8 @@ void diffcore_rename_extended(struct diff_options *options, want_copies = (detect_rename == DIFF_DETECT_COPY); if (dirs_removed && (break_idx || want_copies)) BUG("dirs_removed incompatible with break/copy detection"); + if (break_idx && relevant_sources) + BUG("break detection incompatible with source specification"); if (!minimum_score) minimum_score = DEFAULT_RENAME_SCORE; @@ -1127,9 +1137,10 @@ void diffcore_rename_extended(struct diff_options *options, /* * Cull sources: * - remove ones corresponding to exact renames + * - remove ones not found in relevant_sources */ trace2_region_enter("diff", "cull after exact", options->repo); - remove_unneeded_paths_from_src(want_copies); + remove_unneeded_paths_from_src(want_copies, relevant_sources); trace2_region_leave("diff", "cull after exact", options->repo); } else { /* Determine minimum score to match basenames */ @@ -1148,7 +1159,7 @@ void diffcore_rename_extended(struct diff_options *options, * - remove ones involved in renames (found via exact match) */ trace2_region_enter("diff", "cull after exact", options->repo); - remove_unneeded_paths_from_src(want_copies); + remove_unneeded_paths_from_src(want_copies, NULL); trace2_region_leave("diff", "cull after exact", options->repo); /* Preparation for basename-driven matching. */ @@ -1167,9 +1178,10 @@ void diffcore_rename_extended(struct diff_options *options, /* * Cull sources, again: * - remove ones involved in renames (found via basenames) + * - remove ones not found in relevant_sources */ trace2_region_enter("diff", "cull basename", options->repo); - remove_unneeded_paths_from_src(want_copies); + remove_unneeded_paths_from_src(want_copies, relevant_sources); trace2_region_leave("diff", "cull basename", options->repo); } @@ -1342,5 +1354,5 @@ void diffcore_rename_extended(struct diff_options *options, void diffcore_rename(struct diff_options *options) { - diffcore_rename_extended(options, NULL, NULL); + diffcore_rename_extended(options, NULL, NULL, NULL); } -- cgit v1.2.3 From e4fd06e7e2fa9c433597b76245e38e545eec9ec0 Mon Sep 17 00:00:00 2001 From: Elijah Newren Date: Thu, 11 Mar 2021 00:38:31 +0000 Subject: diffcore-rename: avoid doing basename comparisons for irrelevant sources MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Junio C Hamano --- diffcore-rename.c | 37 +++++++++++++++++++++++++++++++++---- 1 file changed, 33 insertions(+), 4 deletions(-) (limited to 'diffcore-rename.c') diff --git a/diffcore-rename.c b/diffcore-rename.c index 7f6115fd90..e8508541be 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); /* -- cgit v1.2.3