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git/diffcore-rename.c

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50 KiB
C
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/*
*
* 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);
}
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