/* * * Copyright (C) 2005 Junio C Hamano */ #include "cache.h" #include "diff.h" #include "diffcore.h" #include "object-store.h" #include "hashmap.h" #include "progress.h" #include "promisor-remote.h" #include "strmap.h" /* Table of rename/copy destinations */ static struct diff_rename_dst { struct diff_filepair *p; struct diff_filespec *filespec_to_free; int is_rename; /* false -> just a create; true -> rename or copy */ } *rename_dst; static int rename_dst_nr, rename_dst_alloc; /* Mapping from break source pathname to break destination index */ static struct strintmap *break_idx = NULL; static struct diff_rename_dst *locate_rename_dst(struct diff_filepair *p) { /* Lookup by p->ONE->path */ int idx = break_idx ? strintmap_get(break_idx, p->one->path) : -1; return (idx == -1) ? NULL : &rename_dst[idx]; } /* * Returns 0 on success, -1 if we found a duplicate. */ static int add_rename_dst(struct diff_filepair *p) { ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc); rename_dst[rename_dst_nr].p = p; rename_dst[rename_dst_nr].filespec_to_free = NULL; rename_dst[rename_dst_nr].is_rename = 0; rename_dst_nr++; return 0; } /* Table of rename/copy src files */ static struct diff_rename_src { struct diff_filepair *p; unsigned short score; /* to remember the break score */ } *rename_src; static int rename_src_nr, rename_src_alloc; static void register_rename_src(struct diff_filepair *p) { if (p->broken_pair) { if (!break_idx) { break_idx = xmalloc(sizeof(*break_idx)); strintmap_init_with_options(break_idx, -1, NULL, 0); } strintmap_set(break_idx, p->one->path, rename_dst_nr); } ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc); rename_src[rename_src_nr].p = p; rename_src[rename_src_nr].score = p->score; rename_src_nr++; } static int basename_same(struct diff_filespec *src, struct diff_filespec *dst) { int src_len = strlen(src->path), dst_len = strlen(dst->path); while (src_len && dst_len) { char c1 = src->path[--src_len]; char c2 = dst->path[--dst_len]; if (c1 != c2) return 0; if (c1 == '/') return 1; } return (!src_len || src->path[src_len - 1] == '/') && (!dst_len || dst->path[dst_len - 1] == '/'); } struct diff_score { int src; /* index in rename_src */ int dst; /* index in rename_dst */ unsigned short score; short name_score; }; struct inexact_prefetch_options { struct repository *repo; int skip_unmodified; }; static void inexact_prefetch(void *prefetch_options) { struct inexact_prefetch_options *options = prefetch_options; int i; struct oid_array to_fetch = OID_ARRAY_INIT; for (i = 0; i < rename_dst_nr; i++) { if (rename_dst[i].p->renamed_pair) /* * The loop in diffcore_rename() will not need these * blobs, so skip prefetching. */ continue; /* already found exact match */ diff_add_if_missing(options->repo, &to_fetch, rename_dst[i].p->two); } for (i = 0; i < rename_src_nr; i++) { if (options->skip_unmodified && diff_unmodified_pair(rename_src[i].p)) /* * The loop in diffcore_rename() will not need these * blobs, so skip prefetching. */ continue; diff_add_if_missing(options->repo, &to_fetch, rename_src[i].p->one); } promisor_remote_get_direct(options->repo, to_fetch.oid, to_fetch.nr); oid_array_clear(&to_fetch); } static int estimate_similarity(struct repository *r, struct diff_filespec *src, struct diff_filespec *dst, int minimum_score, struct diff_populate_filespec_options *dpf_opt) { /* src points at a file that existed in the original tree (or * optionally a file in the destination tree) and dst points * at a newly created file. They may be quite similar, in which * case we want to say src is renamed to dst or src is copied into * dst, and then some edit has been applied to dst. * * Compare them and return how similar they are, representing * the score as an integer between 0 and MAX_SCORE. * * When there is an exact match, it is considered a better * match than anything else; the destination does not even * call into this function in that case. */ unsigned long max_size, delta_size, base_size, src_copied, literal_added; int score; /* We deal only with regular files. Symlink renames are handled * only when they are exact matches --- in other words, no edits * after renaming. */ if (!S_ISREG(src->mode) || !S_ISREG(dst->mode)) return 0; /* * Need to check that source and destination sizes are * filled in before comparing them. * * If we already have "cnt_data" filled in, we know it's * all good (avoid checking the size for zero, as that * is a possible size - we really should have a flag to * say whether the size is valid or not!) */ dpf_opt->check_size_only = 1; if (!src->cnt_data && diff_populate_filespec(r, src, dpf_opt)) return 0; if (!dst->cnt_data && diff_populate_filespec(r, dst, dpf_opt)) return 0; max_size = ((src->size > dst->size) ? src->size : dst->size); base_size = ((src->size < dst->size) ? src->size : dst->size); delta_size = max_size - base_size; /* We would not consider edits that change the file size so * drastically. delta_size must be smaller than * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size). * * Note that base_size == 0 case is handled here already * and the final score computation below would not have a * divide-by-zero issue. */ if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE) return 0; dpf_opt->check_size_only = 0; if (!src->cnt_data && diff_populate_filespec(r, src, dpf_opt)) return 0; if (!dst->cnt_data && diff_populate_filespec(r, dst, dpf_opt)) return 0; if (diffcore_count_changes(r, src, dst, &src->cnt_data, &dst->cnt_data, &src_copied, &literal_added)) return 0; /* How similar are they? * what percentage of material in dst are from source? */ if (!dst->size) score = 0; /* should not happen */ else score = (int)(src_copied * MAX_SCORE / max_size); return score; } static void record_rename_pair(int dst_index, int src_index, int score) { struct diff_filepair *src = rename_src[src_index].p; struct diff_filepair *dst = rename_dst[dst_index].p; if (dst->renamed_pair) die("internal error: dst already matched."); src->one->rename_used++; src->one->count++; rename_dst[dst_index].filespec_to_free = dst->one; rename_dst[dst_index].is_rename = 1; dst->one = src->one; dst->renamed_pair = 1; if (!strcmp(dst->one->path, dst->two->path)) dst->score = rename_src[src_index].score; else dst->score = score; } /* * We sort the rename similarity matrix with the score, in descending * order (the most similar first). */ static int score_compare(const void *a_, const void *b_) { const struct diff_score *a = a_, *b = b_; /* sink the unused ones to the bottom */ if (a->dst < 0) return (0 <= b->dst); else if (b->dst < 0) return -1; if (a->score == b->score) return b->name_score - a->name_score; return b->score - a->score; } struct file_similarity { struct hashmap_entry entry; int index; struct diff_filespec *filespec; }; static unsigned int hash_filespec(struct repository *r, struct diff_filespec *filespec) { if (!filespec->oid_valid) { if (diff_populate_filespec(r, filespec, NULL)) return 0; hash_object_file(r->hash_algo, filespec->data, filespec->size, "blob", &filespec->oid); } return oidhash(&filespec->oid); } static int find_identical_files(struct hashmap *srcs, int dst_index, struct diff_options *options) { int renames = 0; struct diff_filespec *target = rename_dst[dst_index].p->two; struct file_similarity *p, *best = NULL; int i = 100, best_score = -1; unsigned int hash = hash_filespec(options->repo, target); /* * Find the best source match for specified destination. */ p = hashmap_get_entry_from_hash(srcs, hash, NULL, struct file_similarity, entry); hashmap_for_each_entry_from(srcs, p, entry) { int score; struct diff_filespec *source = p->filespec; /* False hash collision? */ if (!oideq(&source->oid, &target->oid)) continue; /* Non-regular files? If so, the modes must match! */ if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) { if (source->mode != target->mode) continue; } /* Give higher scores to sources that haven't been used already */ score = !source->rename_used; if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY) continue; score += basename_same(source, target); if (score > best_score) { best = p; best_score = score; if (score == 2) break; } /* Too many identical alternatives? Pick one */ if (!--i) break; } if (best) { record_rename_pair(dst_index, best->index, MAX_SCORE); renames++; } return renames; } static void insert_file_table(struct repository *r, struct hashmap *table, int index, struct diff_filespec *filespec) { struct file_similarity *entry = xmalloc(sizeof(*entry)); entry->index = index; entry->filespec = filespec; hashmap_entry_init(&entry->entry, hash_filespec(r, filespec)); hashmap_add(table, &entry->entry); } /* * Find exact renames first. * * The first round matches up the up-to-date entries, * and then during the second round we try to match * cache-dirty entries as well. */ static int find_exact_renames(struct diff_options *options) { int i, renames = 0; struct hashmap file_table; /* Add all sources to the hash table in reverse order, because * later on they will be retrieved in LIFO order. */ hashmap_init(&file_table, NULL, NULL, rename_src_nr); for (i = rename_src_nr-1; i >= 0; i--) insert_file_table(options->repo, &file_table, i, rename_src[i].p->one); /* Walk the destinations and find best source match */ for (i = 0; i < rename_dst_nr; i++) renames += find_identical_files(&file_table, i, options); /* Free the hash data structure and entries */ hashmap_clear_and_free(&file_table, struct file_similarity, entry); return renames; } struct dir_rename_info { struct strintmap idx_map; struct strmap dir_rename_guess; struct strmap *dir_rename_count; struct strintmap *relevant_source_dirs; unsigned setup; }; static char *get_dirname(const char *filename) { char *slash = strrchr(filename, '/'); return slash ? xstrndup(filename, slash - filename) : xstrdup(""); } static void dirname_munge(char *filename) { char *slash = strrchr(filename, '/'); if (!slash) slash = filename; *slash = '\0'; } static const char *get_highest_rename_path(struct strintmap *counts) { int highest_count = 0; const char *highest_destination_dir = NULL; struct hashmap_iter iter; struct strmap_entry *entry; strintmap_for_each_entry(counts, &iter, entry) { const char *destination_dir = entry->key; intptr_t count = (intptr_t)entry->value; if (count > highest_count) { highest_count = count; highest_destination_dir = destination_dir; } } return highest_destination_dir; } static char *UNKNOWN_DIR = "/"; /* placeholder -- short, illegal directory */ static int dir_rename_already_determinable(struct strintmap *counts) { struct hashmap_iter iter; struct strmap_entry *entry; int first = 0, second = 0, unknown = 0; strintmap_for_each_entry(counts, &iter, entry) { const char *destination_dir = entry->key; intptr_t count = (intptr_t)entry->value; if (!strcmp(destination_dir, UNKNOWN_DIR)) { unknown = count; } else if (count >= first) { second = first; first = count; } else if (count >= second) { second = count; } } return first > second + unknown; } static void increment_count(struct dir_rename_info *info, char *old_dir, char *new_dir) { struct strintmap *counts; struct strmap_entry *e; /* Get the {new_dirs -> counts} mapping using old_dir */ e = strmap_get_entry(info->dir_rename_count, old_dir); if (e) { counts = e->value; } else { counts = xmalloc(sizeof(*counts)); strintmap_init_with_options(counts, 0, NULL, 1); strmap_put(info->dir_rename_count, old_dir, counts); } /* Increment the count for new_dir */ strintmap_incr(counts, new_dir, 1); } static void update_dir_rename_counts(struct dir_rename_info *info, struct strintmap *dirs_removed, const char *oldname, const char *newname) { char *old_dir; char *new_dir; const char new_dir_first_char = newname[0]; int first_time_in_loop = 1; if (!info->setup) /* * info->setup is 0 here in two cases: (1) all auxiliary * vars (like dirs_removed) were NULL so * initialize_dir_rename_info() returned early, or (2) * either break detection or copy detection are active so * that we never called initialize_dir_rename_info(). In * the former case, we don't have enough info to know if * directories were renamed (because dirs_removed lets us * know about a necessary prerequisite, namely if they were * removed), and in the latter, we don't care about * directory renames or find_basename_matches. * * This matters because both basename and inexact matching * will also call update_dir_rename_counts(). In either of * the above two cases info->dir_rename_counts will not * have been properly initialized which prevents us from * updating it, but in these two cases we don't care about * dir_rename_counts anyway, so we can just exit early. */ return; old_dir = xstrdup(oldname); new_dir = xstrdup(newname); while (1) { int drd_flag = NOT_RELEVANT; /* Get old_dir, skip if its directory isn't relevant. */ dirname_munge(old_dir); if (info->relevant_source_dirs && !strintmap_contains(info->relevant_source_dirs, old_dir)) break; /* Get new_dir */ dirname_munge(new_dir); /* * When renaming * "a/b/c/d/e/foo.c" -> "a/b/some/thing/else/e/foo.c" * then this suggests that both * a/b/c/d/e/ => a/b/some/thing/else/e/ * a/b/c/d/ => a/b/some/thing/else/ * so we want to increment counters for both. We do NOT, * however, also want to suggest that there was the following * rename: * a/b/c/ => a/b/some/thing/ * so we need to quit at that point. * * Note the when first_time_in_loop, we only strip off the * basename, and we don't care if that's different. */ if (!first_time_in_loop) { char *old_sub_dir = strchr(old_dir, '\0')+1; char *new_sub_dir = strchr(new_dir, '\0')+1; if (!*new_dir) { /* * Special case when renaming to root directory, * i.e. when new_dir == "". In this case, we had * something like * a/b/subdir => subdir * and so dirname_munge() sets things up so that * old_dir = "a/b\0subdir\0" * new_dir = "\0ubdir\0" * We didn't have a '/' to overwrite a '\0' onto * in new_dir, so we have to compare differently. */ if (new_dir_first_char != old_sub_dir[0] || strcmp(old_sub_dir+1, new_sub_dir)) break; } else { if (strcmp(old_sub_dir, new_sub_dir)) break; } } /* * Above we suggested that we'd keep recording renames for * all ancestor directories where the trailing directories * matched, i.e. for * "a/b/c/d/e/foo.c" -> "a/b/some/thing/else/e/foo.c" * we'd increment rename counts for each of * a/b/c/d/e/ => a/b/some/thing/else/e/ * a/b/c/d/ => a/b/some/thing/else/ * However, we only need the rename counts for directories * in dirs_removed whose value is RELEVANT_FOR_SELF. * However, we add one special case of also recording it for * first_time_in_loop because find_basename_matches() can * use that as a hint to find a good pairing. */ if (dirs_removed) drd_flag = strintmap_get(dirs_removed, old_dir); if (drd_flag == RELEVANT_FOR_SELF || first_time_in_loop) increment_count(info, old_dir, new_dir); first_time_in_loop = 0; if (drd_flag == NOT_RELEVANT) break; /* If we hit toplevel directory ("") for old or new dir, quit */ if (!*old_dir || !*new_dir) break; } /* Free resources we don't need anymore */ free(old_dir); free(new_dir); } static void initialize_dir_rename_info(struct dir_rename_info *info, struct strintmap *relevant_sources, struct strintmap *dirs_removed, struct strmap *dir_rename_count, struct strmap *cached_pairs) { struct hashmap_iter iter; struct strmap_entry *entry; int i; if (!dirs_removed && !relevant_sources) { info->setup = 0; return; } info->setup = 1; info->dir_rename_count = dir_rename_count; if (!info->dir_rename_count) { info->dir_rename_count = xmalloc(sizeof(*dir_rename_count)); strmap_init(info->dir_rename_count); } strintmap_init_with_options(&info->idx_map, -1, NULL, 0); strmap_init_with_options(&info->dir_rename_guess, NULL, 0); /* Setup info->relevant_source_dirs */ 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)); strintmap_init(info->relevant_source_dirs, 0 /* unused */); strintmap_for_each_entry(relevant_sources, &iter, entry) { char *dirname = get_dirname(entry->key); if (!dirs_removed || strintmap_contains(dirs_removed, dirname)) strintmap_set(info->relevant_source_dirs, dirname, 0 /* value irrelevant */); free(dirname); } } /* * Loop setting up both info->idx_map, and doing setup of * info->dir_rename_count. */ for (i = 0; i < rename_dst_nr; ++i) { /* * For non-renamed files, make idx_map contain mapping of * filename -> index (index within rename_dst, that is) */ if (!rename_dst[i].is_rename) { char *filename = rename_dst[i].p->two->path; strintmap_set(&info->idx_map, filename, i); continue; } /* * For everything else (i.e. renamed files), make * dir_rename_count contain a map of a map: * old_directory -> {new_directory -> count} * In other words, for every pair look at the directories for * the old filename and the new filename and count how many * times that pairing occurs. */ update_dir_rename_counts(info, dirs_removed, rename_dst[i].p->one->path, rename_dst[i].p->two->path); } /* Add cached_pairs to counts */ strmap_for_each_entry(cached_pairs, &iter, entry) { const char *old_name = entry->key; const char *new_name = entry->value; if (!new_name) /* known delete; ignore it */ continue; update_dir_rename_counts(info, dirs_removed, old_name, new_name); } /* * Now we collapse * dir_rename_count: old_directory -> {new_directory -> count} * down to * dir_rename_guess: old_directory -> best_new_directory * where best_new_directory is the one with the highest count. */ strmap_for_each_entry(info->dir_rename_count, &iter, entry) { /* entry->key is source_dir */ struct strintmap *counts = entry->value; char *best_newdir; best_newdir = xstrdup(get_highest_rename_path(counts)); strmap_put(&info->dir_rename_guess, entry->key, best_newdir); } } void partial_clear_dir_rename_count(struct strmap *dir_rename_count) { struct hashmap_iter iter; struct strmap_entry *entry; strmap_for_each_entry(dir_rename_count, &iter, entry) { struct strintmap *counts = entry->value; strintmap_clear(counts); } strmap_partial_clear(dir_rename_count, 1); } static void cleanup_dir_rename_info(struct dir_rename_info *info, struct strintmap *dirs_removed, int keep_dir_rename_count) { struct hashmap_iter iter; struct strmap_entry *entry; struct string_list to_remove = STRING_LIST_INIT_NODUP; int i; if (!info->setup) return; /* idx_map */ strintmap_clear(&info->idx_map); /* dir_rename_guess */ strmap_clear(&info->dir_rename_guess, 1); /* relevant_source_dirs */ if (info->relevant_source_dirs && info->relevant_source_dirs != dirs_removed) { strintmap_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); strmap_clear(info->dir_rename_count, 1); FREE_AND_NULL(info->dir_rename_count); return; } /* * Although dir_rename_count was passed in * diffcore_rename_extended() and we want to keep it around and * return it to that caller, we first want to remove any counts in * the maps associated with UNKNOWN_DIR entries and any data * associated with directories that weren't renamed. */ strmap_for_each_entry(info->dir_rename_count, &iter, entry) { const char *source_dir = entry->key; struct strintmap *counts = entry->value; if (!strintmap_get(dirs_removed, source_dir)) { string_list_append(&to_remove, source_dir); strintmap_clear(counts); continue; } if (strintmap_contains(counts, UNKNOWN_DIR)) strintmap_remove(counts, UNKNOWN_DIR); } for (i = 0; i < to_remove.nr; ++i) strmap_remove(info->dir_rename_count, to_remove.items[i].string, 1); string_list_clear(&to_remove, 0); } static const char *get_basename(const char *filename) { /* * gitbasename() has to worry about special drives, multiple * directory separator characters, trailing slashes, NULL or * empty strings, etc. We only work on filenames as stored in * git, and thus get to ignore all those complications. */ const char *base = strrchr(filename, '/'); return base ? base + 1 : filename; } static int idx_possible_rename(char *filename, struct dir_rename_info *info) { /* * Our comparison of files with the same basename (see * find_basename_matches() below), is only helpful when after exact * rename detection we have exactly one file with a given basename * among the rename sources and also only exactly one file with * that basename among the rename destinations. When we have * multiple files with the same basename in either set, we do not * know which to compare against. However, there are some * filenames that occur in large numbers (particularly * build-related filenames such as 'Makefile', '.gitignore', or * 'build.gradle' that potentially exist within every single * subdirectory), and for performance we want to be able to quickly * find renames for these files too. * * The reason basename comparisons are a useful heuristic was that it * is common for people to move files across directories while keeping * their filename the same. If we had a way of determining or even * making a good educated guess about which directory these non-unique * basename files had moved the file to, we could check it. * Luckily... * * When an entire directory is in fact renamed, we have two factors * helping us out: * (a) the original directory disappeared giving us a hint * about when we can apply an extra heuristic. * (a) we often have several files within that directory and * subdirectories that are renamed without changes * So, rules for a heuristic: * (0) If there basename matches are non-unique (the condition under * which this function is called) AND * (1) the directory in which the file was found has disappeared * (i.e. dirs_removed is non-NULL and has a relevant entry) THEN * (2) use exact renames of files within the directory to determine * where the directory is likely to have been renamed to. IF * there is at least one exact rename from within that * directory, we can proceed. * (3) If there are multiple places the directory could have been * renamed to based on exact renames, ignore all but one of them. * Just use the destination with the most renames going to it. * (4) Check if applying that directory rename to the original file * would result in a destination filename that is in the * potential rename set. If so, return the index of the * destination file (the index within rename_dst). * (5) Compare the original file and returned destination for * similarity, and if they are sufficiently similar, record the * rename. * * This function, idx_possible_rename(), is only responsible for (4). * The conditions/steps in (1)-(3) are handled via setting up * dir_rename_count and dir_rename_guess in * initialize_dir_rename_info(). Steps (0) and (5) are handled by * the caller of this function. */ char *old_dir, *new_dir; struct strbuf new_path = STRBUF_INIT; int idx; if (!info->setup) return -1; old_dir = get_dirname(filename); new_dir = strmap_get(&info->dir_rename_guess, old_dir); free(old_dir); if (!new_dir) return -1; strbuf_addstr(&new_path, new_dir); strbuf_addch(&new_path, '/'); strbuf_addstr(&new_path, get_basename(filename)); idx = strintmap_get(&info->idx_map, new_path.buf); strbuf_release(&new_path); return idx; } struct basename_prefetch_options { struct repository *repo; struct strintmap *relevant_sources; struct strintmap *sources; struct strintmap *dests; struct dir_rename_info *info; }; static void basename_prefetch(void *prefetch_options) { struct basename_prefetch_options *options = prefetch_options; struct strintmap *relevant_sources = options->relevant_sources; struct strintmap *sources = options->sources; struct strintmap *dests = options->dests; struct dir_rename_info *info = options->info; int i; struct oid_array to_fetch = OID_ARRAY_INIT; /* * TODO: The following loops mirror the code/logic from * find_basename_matches(), though not quite exactly. Maybe * abstract the iteration logic out somehow? */ for (i = 0; i < rename_src_nr; ++i) { char *filename = rename_src[i].p->one->path; const char *base = NULL; intptr_t src_index; intptr_t dst_index; /* Skip irrelevant sources */ if (relevant_sources && !strintmap_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 * to a unique basename in the destinations. Otherwise, * use directory rename heuristics, if possible. */ base = get_basename(filename); src_index = strintmap_get(sources, base); assert(src_index == -1 || src_index == i); if (strintmap_contains(dests, base)) { struct diff_filespec *one, *two; /* Find a matching destination, if possible */ dst_index = strintmap_get(dests, base); if (src_index == -1 || dst_index == -1) { src_index = i; dst_index = idx_possible_rename(filename, info); } if (dst_index == -1) continue; /* Ignore this dest if already used in a rename */ if (rename_dst[dst_index].is_rename) continue; /* already used previously */ one = rename_src[src_index].p->one; two = rename_dst[dst_index].p->two; /* Add the pairs */ diff_add_if_missing(options->repo, &to_fetch, two); diff_add_if_missing(options->repo, &to_fetch, one); } } promisor_remote_get_direct(options->repo, to_fetch.oid, to_fetch.nr); oid_array_clear(&to_fetch); } static int find_basename_matches(struct diff_options *options, int minimum_score, struct dir_rename_info *info, struct strintmap *relevant_sources, struct strintmap *dirs_removed) { /* * When I checked in early 2020, over 76% of file renames in linux * just moved files to a different directory but kept the same * basename. gcc did that with over 64% of renames, gecko did it * with over 79%, and WebKit did it with over 89%. * * Therefore we can bypass the normal exhaustive NxM matrix * comparison of similarities between all potential rename sources * and destinations by instead using file basename as a hint (i.e. * the portion of the filename after the last '/'), checking for * similarity between files with the same basename, and if we find * a pair that are sufficiently similar, record the rename pair and * exclude those two from the NxM matrix. * * This *might* cause us to find a less than optimal pairing (if * there is another file that we are even more similar to but has a * different basename). Given the huge performance advantage * basename matching provides, and given the frequency with which * people use the same basename in real world projects, that's a * trade-off we are willing to accept when doing just rename * detection. * * If someone wants copy detection that implies they are willing to * spend more cycles to find similarities between files, so it may * be less likely that this heuristic is wanted. If someone is * doing break detection, that means they do not want filename * similarity to imply any form of content similiarity, and thus * this heuristic would definitely be incompatible. */ int i, renames = 0; struct strintmap sources; struct strintmap dests; struct diff_populate_filespec_options dpf_options = { .check_binary = 0, .missing_object_cb = NULL, .missing_object_data = NULL }; struct basename_prefetch_options prefetch_options = { .repo = options->repo, .relevant_sources = relevant_sources, .sources = &sources, .dests = &dests, .info = info }; /* * Create maps of basename -> fullname(s) for remaining sources and * dests. */ strintmap_init_with_options(&sources, -1, NULL, 0); strintmap_init_with_options(&dests, -1, NULL, 0); for (i = 0; i < rename_src_nr; ++i) { char *filename = rename_src[i].p->one->path; const char *base; /* exact renames removed in remove_unneeded_paths_from_src() */ assert(!rename_src[i].p->one->rename_used); /* Record index within rename_src (i) if basename is unique */ base = get_basename(filename); if (strintmap_contains(&sources, base)) strintmap_set(&sources, base, -1); else strintmap_set(&sources, base, i); } for (i = 0; i < rename_dst_nr; ++i) { char *filename = rename_dst[i].p->two->path; const char *base; if (rename_dst[i].is_rename) continue; /* involved in exact match already. */ /* Record index within rename_dst (i) if basename is unique */ base = get_basename(filename); if (strintmap_contains(&dests, base)) strintmap_set(&dests, base, -1); else strintmap_set(&dests, base, i); } if (options->repo == the_repository && has_promisor_remote()) { dpf_options.missing_object_cb = basename_prefetch; dpf_options.missing_object_data = &prefetch_options; } /* Now look for basename matchups and do similarity estimation */ for (i = 0; i < rename_src_nr; ++i) { char *filename = rename_src[i].p->one->path; const char *base = NULL; intptr_t src_index; intptr_t dst_index; /* Skip irrelevant sources */ if (relevant_sources && !strintmap_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 * to a unique basename in the destinations. Otherwise, * use directory rename heuristics, if possible. */ base = get_basename(filename); src_index = strintmap_get(&sources, base); assert(src_index == -1 || src_index == i); if (strintmap_contains(&dests, base)) { struct diff_filespec *one, *two; int score; /* Find a matching destination, if possible */ dst_index = strintmap_get(&dests, base); if (src_index == -1 || dst_index == -1) { src_index = i; dst_index = idx_possible_rename(filename, info); } if (dst_index == -1) continue; /* Ignore this dest if already used in a rename */ if (rename_dst[dst_index].is_rename) continue; /* already used previously */ /* Estimate the similarity */ one = rename_src[src_index].p->one; two = rename_dst[dst_index].p->two; score = estimate_similarity(options->repo, one, two, minimum_score, &dpf_options); /* If sufficiently similar, record as rename pair */ if (score < minimum_score) continue; record_rename_pair(dst_index, src_index, score); renames++; update_dir_rename_counts(info, dirs_removed, one->path, two->path); /* * Found a rename so don't need text anymore; if we * didn't find a rename, the filespec_blob would get * re-used when doing the matrix of comparisons. */ diff_free_filespec_blob(one); diff_free_filespec_blob(two); } } strintmap_clear(&sources); strintmap_clear(&dests); return renames; } #define NUM_CANDIDATE_PER_DST 4 static void record_if_better(struct diff_score m[], struct diff_score *o) { int i, worst; /* find the worst one */ worst = 0; for (i = 1; i < NUM_CANDIDATE_PER_DST; i++) if (score_compare(&m[i], &m[worst]) > 0) worst = i; /* is it better than the worst one? */ if (score_compare(&m[worst], o) > 0) m[worst] = *o; } /* * Returns: * 0 if we are under the limit; * 1 if we need to disable inexact rename detection; * 2 if we would be under the limit if we were given -C instead of -C -C. */ static int too_many_rename_candidates(int num_destinations, int num_sources, struct diff_options *options) { int rename_limit = options->rename_limit; int i, limited_sources; options->needed_rename_limit = 0; /* * This basically does a test for the rename matrix not * growing larger than a "rename_limit" square matrix, ie: * * num_destinations * num_sources > rename_limit * rename_limit * * We use st_mult() to check overflow conditions; in the * exceptional circumstance that size_t isn't large enough to hold * the multiplication, the system won't be able to allocate enough * memory for the matrix anyway. */ if (rename_limit <= 0) return 0; /* treat as unlimited */ if (st_mult(num_destinations, num_sources) <= st_mult(rename_limit, rename_limit)) return 0; options->needed_rename_limit = num_sources > num_destinations ? num_sources : num_destinations; /* Are we running under -C -C? */ if (!options->flags.find_copies_harder) return 1; /* Would we bust the limit if we were running under -C? */ for (limited_sources = i = 0; i < num_sources; i++) { if (diff_unmodified_pair(rename_src[i].p)) continue; limited_sources++; } if (st_mult(num_destinations, limited_sources) <= st_mult(rename_limit, rename_limit)) return 2; return 1; } static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies, struct dir_rename_info *info, struct strintmap *dirs_removed) { int count = 0, i; for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) { struct diff_rename_dst *dst; if ((mx[i].dst < 0) || (mx[i].score < minimum_score)) break; /* there is no more usable pair. */ dst = &rename_dst[mx[i].dst]; if (dst->is_rename) continue; /* already done, either exact or fuzzy. */ if (!copies && rename_src[mx[i].src].p->one->rename_used) continue; record_rename_pair(mx[i].dst, mx[i].src, mx[i].score); count++; update_dir_rename_counts(info, dirs_removed, rename_src[mx[i].src].p->one->path, rename_dst[mx[i].dst].p->two->path); } return count; } static void remove_unneeded_paths_from_src(int detecting_copies, struct strintmap *interesting) { int i, new_num_src; if (detecting_copies && !interesting) return; /* nothing to remove */ if (break_idx) return; /* culling incompatible with break detection */ /* * Note on reasons why we cull unneeded sources but not destinations: * 1) Pairings are stored in rename_dst (not rename_src), which we * need to keep around. So, we just can't cull rename_dst even * if we wanted to. But doing so wouldn't help because... * * 2) There is a matrix pairwise comparison that follows the * "Performing inexact rename detection" progress message. * Iterating over the destinations is done in the outer loop, * hence we only iterate over each of those once and we can * easily skip the outer loop early if the destination isn't * relevant. That's only one check per destination path to * skip. * * By contrast, the sources are iterated in the inner loop; if * we check whether a source can be skipped, then we'll be * checking it N separate times, once for each destination. * We don't want to have to iterate over known-not-needed * sources N times each, so avoid that by removing the sources * 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 (!detecting_copies && one->rename_used) continue; /* If we don't care about the source path, skip it */ if (interesting && !strintmap_contains(interesting, one->path)) continue; if (new_num_src < i) memcpy(&rename_src[new_num_src], &rename_src[i], sizeof(struct diff_rename_src)); new_num_src++; } rename_src_nr = new_num_src; } static void handle_early_known_dir_renames(struct dir_rename_info *info, struct strintmap *relevant_sources, struct strintmap *dirs_removed) { /* * Directory renames are determined via an aggregate of all renames * under them and using a "majority wins" rule. The fact that * "majority wins", though, means we don't need all the renames * under the given directory, we only need enough to ensure we have * a majority. */ int i, new_num_src; struct hashmap_iter iter; struct strmap_entry *entry; if (!dirs_removed || !relevant_sources) return; /* nothing to cull */ if (break_idx) return; /* culling incompatbile with break detection */ /* * Supplement dir_rename_count with number of potential renames, * marking all potential rename sources as mapping to UNKNOWN_DIR. */ for (i = 0; i < rename_src_nr; i++) { char *old_dir; struct diff_filespec *one = rename_src[i].p->one; /* * sources that are part of a rename will have already been * removed by a prior call to remove_unneeded_paths_from_src() */ assert(!one->rename_used); old_dir = get_dirname(one->path); while (*old_dir != '\0' && NOT_RELEVANT != strintmap_get(dirs_removed, old_dir)) { char *freeme = old_dir; increment_count(info, old_dir, UNKNOWN_DIR); old_dir = get_dirname(old_dir); /* Free resources we don't need anymore */ free(freeme); } /* * old_dir and new_dir free'd in increment_count, but * get_dirname() gives us a new pointer we need to free for * old_dir. Also, if the loop runs 0 times we need old_dir * to be freed. */ free(old_dir); } /* * For any directory which we need a potential rename detected for * (i.e. those marked as RELEVANT_FOR_SELF in dirs_removed), check * whether we have enough renames to satisfy the "majority rules" * requirement such that detecting any more renames of files under * it won't change the result. For any such directory, mark that * we no longer need to detect a rename for it. However, since we * might need to still detect renames for an ancestor of that * directory, use RELEVANT_FOR_ANCESTOR. */ strmap_for_each_entry(info->dir_rename_count, &iter, entry) { /* entry->key is source_dir */ struct strintmap *counts = entry->value; if (strintmap_get(dirs_removed, entry->key) == RELEVANT_FOR_SELF && dir_rename_already_determinable(counts)) { strintmap_set(dirs_removed, entry->key, RELEVANT_FOR_ANCESTOR); } } for (i = 0, new_num_src = 0; i < rename_src_nr; i++) { struct diff_filespec *one = rename_src[i].p->one; int val; val = strintmap_get(relevant_sources, one->path); /* * sources that were not found in relevant_sources should * have already been removed by a prior call to * remove_unneeded_paths_from_src() */ assert(val != -1); if (val == RELEVANT_LOCATION) { int removable = 1; char *dir = get_dirname(one->path); while (1) { char *freeme = dir; int res = strintmap_get(dirs_removed, dir); /* Quit if not found or irrelevant */ if (res == NOT_RELEVANT) break; /* If RELEVANT_FOR_SELF, can't remove */ if (res == RELEVANT_FOR_SELF) { removable = 0; break; } /* Else continue searching upwards */ assert(res == RELEVANT_FOR_ANCESTOR); dir = get_dirname(dir); free(freeme); } free(dir); if (removable) { strintmap_set(relevant_sources, one->path, RELEVANT_NO_MORE); continue; } } if (new_num_src < i) memcpy(&rename_src[new_num_src], &rename_src[i], sizeof(struct diff_rename_src)); new_num_src++; } rename_src_nr = new_num_src; } void diffcore_rename_extended(struct diff_options *options, struct strintmap *relevant_sources, struct strintmap *dirs_removed, struct strmap *dir_rename_count, struct strmap *cached_pairs) { int detect_rename = options->detect_rename; int minimum_score = options->rename_score; struct diff_queue_struct *q = &diff_queued_diff; struct diff_queue_struct outq; struct diff_score *mx; int i, j, rename_count, skip_unmodified = 0; int num_destinations, dst_cnt; int num_sources, want_copies; struct progress *progress = NULL; struct dir_rename_info info; struct diff_populate_filespec_options dpf_options = { .check_binary = 0, .missing_object_cb = NULL, .missing_object_data = NULL }; struct inexact_prefetch_options prefetch_options = { .repo = options->repo }; trace2_region_enter("diff", "setup", options->repo); info.setup = 0; assert(!dir_rename_count || strmap_empty(dir_rename_count)); 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; for (i = 0; i < q->nr; i++) { struct diff_filepair *p = q->queue[i]; if (!DIFF_FILE_VALID(p->one)) { if (!DIFF_FILE_VALID(p->two)) continue; /* unmerged */ else if (options->single_follow && strcmp(options->single_follow, p->two->path)) continue; /* not interested */ else if (!options->flags.rename_empty && is_empty_blob_oid(&p->two->oid)) continue; else if (add_rename_dst(p) < 0) { warning("skipping rename detection, detected" " duplicate destination '%s'", p->two->path); goto cleanup; } } else if (!options->flags.rename_empty && is_empty_blob_oid(&p->one->oid)) continue; else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) { /* * If the source is a broken "delete", and * they did not really want to get broken, * that means the source actually stays. * So we increment the "rename_used" score * by one, to indicate ourselves as a user */ if (p->broken_pair && !p->score) p->one->rename_used++; register_rename_src(p); } else if (want_copies) { /* * Increment the "rename_used" score by * one, to indicate ourselves as a user. */ p->one->rename_used++; register_rename_src(p); } } trace2_region_leave("diff", "setup", options->repo); if (rename_dst_nr == 0 || rename_src_nr == 0) goto cleanup; /* nothing to do */ trace2_region_enter("diff", "exact renames", options->repo); /* * We really want to cull the candidates list early * with cheap tests in order to avoid doing deltas. */ rename_count = find_exact_renames(options); trace2_region_leave("diff", "exact renames", options->repo); /* Did we only want exact renames? */ if (minimum_score == MAX_SCORE) goto cleanup; num_sources = rename_src_nr; if (want_copies || break_idx) { /* * 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, relevant_sources); trace2_region_leave("diff", "cull after exact", options->repo); } else { /* Determine minimum score to match basenames */ double factor = 0.5; char *basename_factor = getenv("GIT_BASENAME_FACTOR"); int min_basename_score; if (basename_factor) factor = strtol(basename_factor, NULL, 10)/100.0; assert(factor >= 0.0 && factor <= 1.0); min_basename_score = minimum_score + (int)(factor * (MAX_SCORE - minimum_score)); /* * Cull sources: * - 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, NULL); trace2_region_leave("diff", "cull after exact", options->repo); /* Preparation for basename-driven matching. */ trace2_region_enter("diff", "dir rename setup", options->repo); initialize_dir_rename_info(&info, relevant_sources, dirs_removed, dir_rename_count, cached_pairs); trace2_region_leave("diff", "dir rename setup", options->repo); /* Utilize file basenames to quickly find renames. */ trace2_region_enter("diff", "basename matches", options->repo); rename_count += find_basename_matches(options, min_basename_score, &info, relevant_sources, dirs_removed); trace2_region_leave("diff", "basename matches", options->repo); /* * Cull sources, again: * - remove ones involved in renames (found via basenames) * - remove ones not found in relevant_sources * and * - remove ones in relevant_sources which are needed only * for directory renames IF no ancestory directory * actually needs to know any more individual path * renames under them */ trace2_region_enter("diff", "cull basename", options->repo); remove_unneeded_paths_from_src(want_copies, relevant_sources); handle_early_known_dir_renames(&info, relevant_sources, dirs_removed); trace2_region_leave("diff", "cull basename", options->repo); } /* Calculate how many rename destinations are left */ num_destinations = (rename_dst_nr - rename_count); num_sources = rename_src_nr; /* rename_src_nr reflects lower number */ /* All done? */ if (!num_destinations || !num_sources) goto cleanup; switch (too_many_rename_candidates(num_destinations, num_sources, options)) { case 1: goto cleanup; case 2: options->degraded_cc_to_c = 1; skip_unmodified = 1; break; default: break; } trace2_region_enter("diff", "inexact renames", options->repo); if (options->show_rename_progress) { progress = start_delayed_progress( _("Performing inexact rename detection"), (uint64_t)num_destinations * (uint64_t)num_sources); } /* Finish setting up dpf_options */ prefetch_options.skip_unmodified = skip_unmodified; if (options->repo == the_repository && has_promisor_remote()) { dpf_options.missing_object_cb = inexact_prefetch; dpf_options.missing_object_data = &prefetch_options; } CALLOC_ARRAY(mx, st_mult(NUM_CANDIDATE_PER_DST, num_destinations)); for (dst_cnt = i = 0; i < rename_dst_nr; i++) { struct diff_filespec *two = rename_dst[i].p->two; struct diff_score *m; if (rename_dst[i].is_rename) continue; /* exact or basename match already handled */ m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST]; for (j = 0; j < NUM_CANDIDATE_PER_DST; j++) m[j].dst = -1; for (j = 0; j < rename_src_nr; j++) { struct diff_filespec *one = rename_src[j].p->one; struct diff_score this_src; assert(!one->rename_used || want_copies || break_idx); if (skip_unmodified && diff_unmodified_pair(rename_src[j].p)) continue; this_src.score = estimate_similarity(options->repo, one, two, minimum_score, &dpf_options); this_src.name_score = basename_same(one, two); this_src.dst = i; this_src.src = j; record_if_better(m, &this_src); /* * Once we run estimate_similarity, * We do not need the text anymore. */ diff_free_filespec_blob(one); diff_free_filespec_blob(two); } dst_cnt++; display_progress(progress, (uint64_t)dst_cnt * (uint64_t)num_sources); } stop_progress(&progress); /* cost matrix sorted by most to least similar pair */ STABLE_QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare); rename_count += find_renames(mx, dst_cnt, minimum_score, 0, &info, dirs_removed); if (want_copies) rename_count += find_renames(mx, dst_cnt, minimum_score, 1, &info, dirs_removed); free(mx); trace2_region_leave("diff", "inexact renames", options->repo); cleanup: /* At this point, we have found some renames and copies and they * are recorded in rename_dst. The original list is still in *q. */ trace2_region_enter("diff", "write back to queue", options->repo); DIFF_QUEUE_CLEAR(&outq); for (i = 0; i < q->nr; i++) { struct diff_filepair *p = q->queue[i]; struct diff_filepair *pair_to_free = NULL; if (DIFF_PAIR_UNMERGED(p)) { diff_q(&outq, p); } else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) { /* Creation */ diff_q(&outq, p); } else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) { /* * Deletion * * We would output this delete record if: * * (1) this is a broken delete and the counterpart * broken create remains in the output; or * (2) this is not a broken delete, and rename_dst * does not have a rename/copy to move p->one->path * out of existence. * * Otherwise, the counterpart broken create * has been turned into a rename-edit; or * delete did not have a matching create to * begin with. */ if (DIFF_PAIR_BROKEN(p)) { /* broken delete */ struct diff_rename_dst *dst = locate_rename_dst(p); if (!dst) BUG("tracking failed somehow; failed to find associated dst for broken pair"); if (dst->is_rename) /* counterpart is now rename/copy */ pair_to_free = p; } else { if (p->one->rename_used) /* this path remains */ pair_to_free = p; } if (!pair_to_free) diff_q(&outq, p); } else if (!diff_unmodified_pair(p)) /* all the usual ones need to be kept */ diff_q(&outq, p); else /* no need to keep unmodified pairs */ pair_to_free = p; if (pair_to_free) diff_free_filepair(pair_to_free); } diff_debug_queue("done copying original", &outq); free(q->queue); *q = outq; diff_debug_queue("done collapsing", q); for (i = 0; i < rename_dst_nr; i++) if (rename_dst[i].filespec_to_free) free_filespec(rename_dst[i].filespec_to_free); cleanup_dir_rename_info(&info, dirs_removed, dir_rename_count != NULL); FREE_AND_NULL(rename_dst); rename_dst_nr = rename_dst_alloc = 0; FREE_AND_NULL(rename_src); rename_src_nr = rename_src_alloc = 0; if (break_idx) { strintmap_clear(break_idx); FREE_AND_NULL(break_idx); } trace2_region_leave("diff", "write back to queue", options->repo); return; } void diffcore_rename(struct diff_options *options) { diffcore_rename_extended(options, NULL, NULL, NULL, NULL); }