git/diffcore-rename.c
Junio C Hamano 8aade107dd progress: simplify "delayed" progress API
We used to expose the full power of the delayed progress API to the
callers, so that they can specify, not just the message to show and
expected total amount of work that is used to compute the percentage
of work performed so far, the percent-threshold parameter P and the
delay-seconds parameter N.  The progress meter starts to show at N
seconds into the operation only if we have not yet completed P per-cent
of the total work.

Most callers used either (0%, 2s) or (50%, 1s) as (P, N), but there
are oddballs that chose more random-looking values like 95%.

For a smoother workload, (50%, 1s) would allow us to start showing
the progress meter earlier than (0%, 2s), while keeping the chance
of not showing progress meter for long running operation the same as
the latter.  For a task that would take 2s or more to complete, it
is likely that less than half of it would complete within the first
second, if the workload is smooth.  But for a spiky workload whose
earlier part is easier, such a setting is likely to fail to show the
progress meter entirely and (0%, 2s) is more appropriate.

But that is merely a theory.  Realistically, it is of dubious value
to ask each codepath to carefully consider smoothness of their
workload and specify their own setting by passing two extra
parameters.  Let's simplify the API by dropping both parameters and
have everybody use (0%, 2s).

Oh, by the way, the percent-threshold parameter and the structure
member were consistently misspelled, which also is now fixed ;-)

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-19 14:01:34 -07:00

676 lines
18 KiB
C

/*
* Copyright (C) 2005 Junio C Hamano
*/
#include "cache.h"
#include "diff.h"
#include "diffcore.h"
#include "hashmap.h"
#include "progress.h"
/* Table of rename/copy destinations */
static struct diff_rename_dst {
struct diff_filespec *two;
struct diff_filepair *pair;
} *rename_dst;
static int rename_dst_nr, rename_dst_alloc;
static int find_rename_dst(struct diff_filespec *two)
{
int first, last;
first = 0;
last = rename_dst_nr;
while (last > first) {
int next = (last + first) >> 1;
struct diff_rename_dst *dst = &(rename_dst[next]);
int cmp = strcmp(two->path, dst->two->path);
if (!cmp)
return next;
if (cmp < 0) {
last = next;
continue;
}
first = next+1;
}
return -first - 1;
}
static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two)
{
int ofs = find_rename_dst(two);
return ofs < 0 ? NULL : &rename_dst[ofs];
}
/*
* Returns 0 on success, -1 if we found a duplicate.
*/
static int add_rename_dst(struct diff_filespec *two)
{
int first = find_rename_dst(two);
if (first >= 0)
return -1;
first = -first - 1;
/* insert to make it at "first" */
ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
rename_dst_nr++;
if (first < rename_dst_nr)
memmove(rename_dst + first + 1, rename_dst + first,
(rename_dst_nr - first - 1) * sizeof(*rename_dst));
rename_dst[first].two = alloc_filespec(two->path);
fill_filespec(rename_dst[first].two, &two->oid, two->oid_valid,
two->mode);
rename_dst[first].pair = NULL;
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 struct diff_rename_src *register_rename_src(struct diff_filepair *p)
{
int first, last;
struct diff_filespec *one = p->one;
unsigned short score = p->score;
first = 0;
last = rename_src_nr;
while (last > first) {
int next = (last + first) >> 1;
struct diff_rename_src *src = &(rename_src[next]);
int cmp = strcmp(one->path, src->p->one->path);
if (!cmp)
return src;
if (cmp < 0) {
last = next;
continue;
}
first = next+1;
}
/* insert to make it at "first" */
ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
rename_src_nr++;
if (first < rename_src_nr)
memmove(rename_src + first + 1, rename_src + first,
(rename_src_nr - first - 1) * sizeof(*rename_src));
rename_src[first].p = p;
rename_src[first].score = score;
return &(rename_src[first]);
}
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;
};
static int estimate_similarity(struct diff_filespec *src,
struct diff_filespec *dst,
int minimum_score)
{
/* 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!)
*/
if (!src->cnt_data &&
diff_populate_filespec(src, CHECK_SIZE_ONLY))
return 0;
if (!dst->cnt_data &&
diff_populate_filespec(dst, CHECK_SIZE_ONLY))
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;
if (!src->cnt_data && diff_populate_filespec(src, 0))
return 0;
if (!dst->cnt_data && diff_populate_filespec(dst, 0))
return 0;
if (diffcore_count_changes(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_filespec *src, *dst;
struct diff_filepair *dp;
if (rename_dst[dst_index].pair)
die("internal error: dst already matched.");
src = rename_src[src_index].p->one;
src->rename_used++;
src->count++;
dst = rename_dst[dst_index].two;
dst->count++;
dp = diff_queue(NULL, src, dst);
dp->renamed_pair = 1;
if (!strcmp(src->path, dst->path))
dp->score = rename_src[src_index].score;
else
dp->score = score;
rename_dst[dst_index].pair = dp;
}
/*
* 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 diff_filespec *filespec)
{
if (!filespec->oid_valid) {
if (diff_populate_filespec(filespec, 0))
return 0;
hash_sha1_file(filespec->data, filespec->size, "blob",
filespec->oid.hash);
}
return sha1hash(filespec->oid.hash);
}
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].two;
struct file_similarity *p, *best = NULL;
int i = 100, best_score = -1;
/*
* Find the best source match for specified destination.
*/
p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
for (; p; p = hashmap_get_next(srcs, p)) {
int score;
struct diff_filespec *source = p->filespec;
/* False hash collision? */
if (oidcmp(&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 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, hash_filespec(filespec));
hashmap_add(table, 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(&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_free(&file_table, 1);
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_create,
struct diff_options *options)
{
int rename_limit = options->rename_limit;
int num_src = rename_src_nr;
int i;
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_create * num_src > rename_limit * rename_limit
*
* but handles the potential overflow case specially (and we
* assume at least 32-bit integers)
*/
if (rename_limit <= 0 || rename_limit > 32767)
rename_limit = 32767;
if ((num_create <= rename_limit || num_src <= rename_limit) &&
(num_create * num_src <= rename_limit * rename_limit))
return 0;
options->needed_rename_limit =
num_src > num_create ? num_src : num_create;
/* Are we running under -C -C? */
if (!DIFF_OPT_TST(options, FIND_COPIES_HARDER))
return 1;
/* Would we bust the limit if we were running under -C? */
for (num_src = i = 0; i < rename_src_nr; i++) {
if (diff_unmodified_pair(rename_src[i].p))
continue;
num_src++;
}
if ((num_create <= rename_limit || num_src <= rename_limit) &&
(num_create * num_src <= rename_limit * rename_limit))
return 2;
return 1;
}
static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
{
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->pair)
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++;
}
return count;
}
void diffcore_rename(struct diff_options *options)
{
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_create, dst_cnt;
struct progress *progress = NULL;
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 (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
is_empty_blob_oid(&p->two->oid))
continue;
else if (add_rename_dst(p->two) < 0) {
warning("skipping rename detection, detected"
" duplicate destination '%s'",
p->two->path);
goto cleanup;
}
}
else if (!DIFF_OPT_TST(options, 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 (detect_rename == DIFF_DETECT_COPY) {
/*
* Increment the "rename_used" score by
* one, to indicate ourselves as a user.
*/
p->one->rename_used++;
register_rename_src(p);
}
}
if (rename_dst_nr == 0 || rename_src_nr == 0)
goto cleanup; /* nothing to do */
/*
* We really want to cull the candidates list early
* with cheap tests in order to avoid doing deltas.
*/
rename_count = find_exact_renames(options);
/* Did we only want exact renames? */
if (minimum_score == MAX_SCORE)
goto cleanup;
/*
* Calculate how many renames are left (but all the source
* files still remain as options for rename/copies!)
*/
num_create = (rename_dst_nr - rename_count);
/* All done? */
if (!num_create)
goto cleanup;
switch (too_many_rename_candidates(num_create, options)) {
case 1:
goto cleanup;
case 2:
options->degraded_cc_to_c = 1;
skip_unmodified = 1;
break;
default:
break;
}
if (options->show_rename_progress) {
progress = start_delayed_progress(
_("Performing inexact rename detection"),
rename_dst_nr * rename_src_nr);
}
mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
struct diff_filespec *two = rename_dst[i].two;
struct diff_score *m;
if (rename_dst[i].pair)
continue; /* dealt with exact match already. */
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;
if (skip_unmodified &&
diff_unmodified_pair(rename_src[j].p))
continue;
this_src.score = estimate_similarity(one, two,
minimum_score);
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, (i+1)*rename_src_nr);
}
stop_progress(&progress);
/* cost matrix sorted by most to least similar pair */
QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
if (detect_rename == DIFF_DETECT_COPY)
rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
free(mx);
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.
*/
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
*
* We would output this create record if it has
* not been turned into a rename/copy already.
*/
struct diff_rename_dst *dst = locate_rename_dst(p->two);
if (dst && dst->pair) {
diff_q(&outq, dst->pair);
pair_to_free = p;
}
else
/* no matching rename/copy source, so
* record this as a 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->one);
if (dst && dst->pair)
/* 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)
;
else
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++)
free_filespec(rename_dst[i].two);
FREE_AND_NULL(rename_dst);
rename_dst_nr = rename_dst_alloc = 0;
FREE_AND_NULL(rename_src);
rename_src_nr = rename_src_alloc = 0;
return;
}