diff options
author | Elijah Newren <newren@gmail.com> | 2018-04-19 20:58:05 +0300 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2018-05-08 10:11:00 +0300 |
commit | 7fe40b88efc721bfcbe69f00f950eb9f7a9cd236 (patch) | |
tree | 3a2883c0f0693231dbf2a5f92559076b3438401d /merge-recursive.c | |
parent | ffc16c490ad533bc07e6d8ec0226b426166e8442 (diff) |
merge-recursive: add get_directory_renames()
This populates a set of directory renames for us. The set of directory
renames is not yet used, but will be in subsequent commits.
Note that the use of a string_list for possible_new_dirs in the new
dir_rename_entry struct implies an O(n^2) algorithm; however, in practice
I expect the number of distinct directories that files were renamed into
from a single original directory to be O(1). My guess is that n has a
mode of 1 and a mean of less than 2, so, for now, string_list seems good
enough for possible_new_dirs.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'merge-recursive.c')
-rw-r--r-- | merge-recursive.c | 224 |
1 files changed, 221 insertions, 3 deletions
diff --git a/merge-recursive.c b/merge-recursive.c index 30894c1cc7..a1a9e62a8d 100644 --- a/merge-recursive.c +++ b/merge-recursive.c @@ -49,6 +49,44 @@ static unsigned int path_hash(const char *path) return ignore_case ? strihash(path) : strhash(path); } +static struct dir_rename_entry *dir_rename_find_entry(struct hashmap *hashmap, + char *dir) +{ + struct dir_rename_entry key; + + if (dir == NULL) + return NULL; + hashmap_entry_init(&key, strhash(dir)); + key.dir = dir; + return hashmap_get(hashmap, &key, NULL); +} + +static int dir_rename_cmp(const void *unused_cmp_data, + const void *entry, + const void *entry_or_key, + const void *unused_keydata) +{ + const struct dir_rename_entry *e1 = entry; + const struct dir_rename_entry *e2 = entry_or_key; + + return strcmp(e1->dir, e2->dir); +} + +static void dir_rename_init(struct hashmap *map) +{ + hashmap_init(map, dir_rename_cmp, NULL, 0); +} + +static void dir_rename_entry_init(struct dir_rename_entry *entry, + char *directory) +{ + hashmap_entry_init(entry, strhash(directory)); + entry->dir = directory; + entry->non_unique_new_dir = 0; + strbuf_init(&entry->new_dir, 0); + string_list_init(&entry->possible_new_dirs, 0); +} + static void flush_output(struct merge_options *o) { if (o->buffer_output < 2 && o->obuf.len) { @@ -1357,6 +1395,169 @@ static struct diff_queue_struct *get_diffpairs(struct merge_options *o, return ret; } +static void get_renamed_dir_portion(const char *old_path, const char *new_path, + char **old_dir, char **new_dir) +{ + char *end_of_old, *end_of_new; + int old_len, new_len; + + *old_dir = NULL; + *new_dir = NULL; + + /* + * For + * "a/b/c/d/e/foo.c" -> "a/b/some/thing/else/e/foo.c" + * the "e/foo.c" part is the same, we just want to know that + * "a/b/c/d" was renamed to "a/b/some/thing/else" + * so, for this example, this function returns "a/b/c/d" in + * *old_dir and "a/b/some/thing/else" in *new_dir. + * + * Also, if the basename of the file changed, we don't care. We + * want to know which portion of the directory, if any, changed. + */ + end_of_old = strrchr(old_path, '/'); + end_of_new = strrchr(new_path, '/'); + + if (end_of_old == NULL || end_of_new == NULL) + return; + while (*--end_of_new == *--end_of_old && + end_of_old != old_path && + end_of_new != new_path) + ; /* Do nothing; all in the while loop */ + /* + * We've found the first non-matching character in the directory + * paths. That means the current directory we were comparing + * represents the rename. Move end_of_old and end_of_new back + * to the full directory name. + */ + if (*end_of_old == '/') + end_of_old++; + if (*end_of_old != '/') + end_of_new++; + end_of_old = strchr(end_of_old, '/'); + end_of_new = strchr(end_of_new, '/'); + + /* + * It may have been the case that old_path and new_path were the same + * directory all along. Don't claim a rename if they're the same. + */ + old_len = end_of_old - old_path; + new_len = end_of_new - new_path; + + if (old_len != new_len || strncmp(old_path, new_path, old_len)) { + *old_dir = xstrndup(old_path, old_len); + *new_dir = xstrndup(new_path, new_len); + } +} + +static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs, + struct tree *tree) +{ + struct hashmap *dir_renames; + struct hashmap_iter iter; + struct dir_rename_entry *entry; + int i; + + /* + * Typically, we think of a directory rename as all files from a + * certain directory being moved to a target directory. However, + * what if someone first moved two files from the original + * directory in one commit, and then renamed the directory + * somewhere else in a later commit? At merge time, we just know + * that files from the original directory went to two different + * places, and that the bulk of them ended up in the same place. + * We want each directory rename to represent where the bulk of the + * files from that directory end up; this function exists to find + * where the bulk of the files went. + * + * The first loop below simply iterates through the list of file + * renames, finding out how often each directory rename pair + * possibility occurs. + */ + dir_renames = xmalloc(sizeof(*dir_renames)); + dir_rename_init(dir_renames); + for (i = 0; i < pairs->nr; ++i) { + struct string_list_item *item; + int *count; + struct diff_filepair *pair = pairs->queue[i]; + char *old_dir, *new_dir; + + /* File not part of directory rename if it wasn't renamed */ + if (pair->status != 'R') + continue; + + get_renamed_dir_portion(pair->one->path, pair->two->path, + &old_dir, &new_dir); + if (!old_dir) + /* Directory didn't change at all; ignore this one. */ + continue; + + entry = dir_rename_find_entry(dir_renames, old_dir); + if (!entry) { + entry = xmalloc(sizeof(*entry)); + dir_rename_entry_init(entry, old_dir); + hashmap_put(dir_renames, entry); + } else { + free(old_dir); + } + item = string_list_lookup(&entry->possible_new_dirs, new_dir); + if (!item) { + item = string_list_insert(&entry->possible_new_dirs, + new_dir); + item->util = xcalloc(1, sizeof(int)); + } else { + free(new_dir); + } + count = item->util; + *count += 1; + } + + /* + * For each directory with files moved out of it, we find out which + * target directory received the most files so we can declare it to + * be the "winning" target location for the directory rename. This + * winner gets recorded in new_dir. If there is no winner + * (multiple target directories received the same number of files), + * we set non_unique_new_dir. Once we've determined the winner (or + * that there is no winner), we no longer need possible_new_dirs. + */ + hashmap_iter_init(dir_renames, &iter); + while ((entry = hashmap_iter_next(&iter))) { + int max = 0; + int bad_max = 0; + char *best = NULL; + + for (i = 0; i < entry->possible_new_dirs.nr; i++) { + int *count = entry->possible_new_dirs.items[i].util; + + if (*count == max) + bad_max = max; + else if (*count > max) { + max = *count; + best = entry->possible_new_dirs.items[i].string; + } + } + if (bad_max == max) + entry->non_unique_new_dir = 1; + else { + assert(entry->new_dir.len == 0); + strbuf_addstr(&entry->new_dir, best); + } + /* + * The relevant directory sub-portion of the original full + * filepaths were xstrndup'ed before inserting into + * possible_new_dirs, and instead of manually iterating the + * list and free'ing each, just lie and tell + * possible_new_dirs that it did the strdup'ing so that it + * will free them for us. + */ + entry->possible_new_dirs.strdup_strings = 1; + string_list_clear(&entry->possible_new_dirs, 1); + } + + return dir_renames; +} + /* * Get information of all renames which occurred in 'pairs', making use of * any implicit directory renames inferred from the other side of history. @@ -1668,8 +1869,21 @@ struct rename_info { struct string_list *merge_renames; }; -static void initial_cleanup_rename(struct diff_queue_struct *pairs) +static void initial_cleanup_rename(struct diff_queue_struct *pairs, + struct hashmap *dir_renames) { + struct hashmap_iter iter; + struct dir_rename_entry *e; + + hashmap_iter_init(dir_renames, &iter); + while ((e = hashmap_iter_next(&iter))) { + free(e->dir); + strbuf_release(&e->new_dir); + /* possible_new_dirs already cleared in get_directory_renames */ + } + hashmap_free(dir_renames, 1); + free(dir_renames); + free(pairs->queue); free(pairs); } @@ -1682,6 +1896,7 @@ static int handle_renames(struct merge_options *o, struct rename_info *ri) { struct diff_queue_struct *head_pairs, *merge_pairs; + struct hashmap *dir_re_head, *dir_re_merge; int clean; ri->head_renames = NULL; @@ -1693,6 +1908,9 @@ static int handle_renames(struct merge_options *o, head_pairs = get_diffpairs(o, common, head); merge_pairs = get_diffpairs(o, common, merge); + dir_re_head = get_directory_renames(head_pairs, head); + dir_re_merge = get_directory_renames(merge_pairs, merge); + ri->head_renames = get_renames(o, head_pairs, head, common, head, merge, entries); ri->merge_renames = get_renames(o, merge_pairs, merge, @@ -1704,8 +1922,8 @@ static int handle_renames(struct merge_options *o, * data structures are still needed and referenced in * process_entry(). But there are a few things we can free now. */ - initial_cleanup_rename(head_pairs); - initial_cleanup_rename(merge_pairs); + initial_cleanup_rename(head_pairs, dir_re_head); + initial_cleanup_rename(merge_pairs, dir_re_merge); return clean; } |