mirror of
https://github.com/git/git
synced 2024-08-25 02:35:46 +00:00
![Junio C Hamano](/assets/img/avatar_default.png)
A new diffcore transformation, diffcore-break.c, is introduced. When the -B flag is given, a patch that represents a complete rewrite is broken into a deletion followed by a creation. This makes it easier to review such a complete rewrite patch. The -B flag takes the same syntax as the -M and -C flags to specify the minimum amount of non-source material the resulting file needs to have to be considered a complete rewrite, and defaults to 99% if not specified. As the new test t4008-diff-break-rewrite.sh demonstrates, if a file is a complete rewrite, it is broken into a delete/create pair, which can further be subjected to the usual rename detection if -M or -C is used. For example, if file0 gets completely rewritten to make it as if it were rather based on file1 which itself disappeared, the following happens: The original change looks like this: file0 --> file0' (quite different from file0) file1 --> /dev/null After diffcore-break runs, it would become this: file0 --> /dev/null /dev/null --> file0' file1 --> /dev/null Then diffcore-rename matches them up: file1 --> file0' The internal score values are finer grained now. Earlier maximum of 10000 has been raised to 60000; there is no user visible changes but there is no reason to waste available bits. Signed-off-by: Junio C Hamano <junkio@cox.net> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
417 lines
11 KiB
C
417 lines
11 KiB
C
/*
|
|
* Copyright (C) 2005 Junio C Hamano
|
|
*/
|
|
#include "cache.h"
|
|
#include "diff.h"
|
|
#include "diffcore.h"
|
|
#include "delta.h"
|
|
#include "count-delta.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 struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
|
|
int insert_ok)
|
|
{
|
|
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 dst;
|
|
if (cmp < 0) {
|
|
last = next;
|
|
continue;
|
|
}
|
|
first = next+1;
|
|
}
|
|
/* not found */
|
|
if (!insert_ok)
|
|
return NULL;
|
|
/* insert to make it at "first" */
|
|
if (rename_dst_alloc <= rename_dst_nr) {
|
|
rename_dst_alloc = alloc_nr(rename_dst_alloc);
|
|
rename_dst = xrealloc(rename_dst,
|
|
rename_dst_alloc * sizeof(*rename_dst));
|
|
}
|
|
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 = two;
|
|
rename_dst[first].pair = NULL;
|
|
return &(rename_dst[first]);
|
|
}
|
|
|
|
/* Table of rename/copy src files */
|
|
static struct diff_rename_src {
|
|
struct diff_filespec *one;
|
|
unsigned src_stays : 1;
|
|
} *rename_src;
|
|
static int rename_src_nr, rename_src_alloc;
|
|
|
|
static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
|
|
int src_stays)
|
|
{
|
|
int first, last;
|
|
|
|
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->one->path);
|
|
if (!cmp)
|
|
return src;
|
|
if (cmp < 0) {
|
|
last = next;
|
|
continue;
|
|
}
|
|
first = next+1;
|
|
}
|
|
|
|
/* insert to make it at "first" */
|
|
if (rename_src_alloc <= rename_src_nr) {
|
|
rename_src_alloc = alloc_nr(rename_src_alloc);
|
|
rename_src = xrealloc(rename_src,
|
|
rename_src_alloc * sizeof(*rename_src));
|
|
}
|
|
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].one = one;
|
|
rename_src[first].src_stays = src_stays;
|
|
return &(rename_src[first]);
|
|
}
|
|
|
|
static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst)
|
|
{
|
|
if (src->sha1_valid && dst->sha1_valid &&
|
|
!memcmp(src->sha1, dst->sha1, 20))
|
|
return 1;
|
|
if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
|
|
return 0;
|
|
if (src->size != dst->size)
|
|
return 0;
|
|
if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
|
|
return 0;
|
|
if (src->size == dst->size &&
|
|
!memcmp(src->data, dst->data, src->size))
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
struct diff_score {
|
|
int src; /* index in rename_src */
|
|
int dst; /* index in rename_dst */
|
|
int 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.
|
|
*/
|
|
void *delta;
|
|
unsigned long delta_size, base_size;
|
|
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;
|
|
|
|
delta_size = ((src->size < dst->size) ?
|
|
(dst->size - src->size) : (src->size - dst->size));
|
|
base_size = ((src->size < dst->size) ? src->size : dst->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 (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
|
|
return 0;
|
|
|
|
if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
|
|
return 0; /* error but caught downstream */
|
|
|
|
delta = diff_delta(src->data, src->size,
|
|
dst->data, dst->size,
|
|
&delta_size);
|
|
|
|
/* A delta that has a lot of literal additions would have
|
|
* big delta_size no matter what else it does.
|
|
*/
|
|
if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
|
|
return 0;
|
|
|
|
/* Estimate the edit size by interpreting delta. */
|
|
delta_size = count_delta(delta, delta_size);
|
|
free(delta);
|
|
if (delta_size == UINT_MAX)
|
|
return 0;
|
|
|
|
/*
|
|
* Now we will give some score to it. 100% edit gets 0 points
|
|
* and 0% edit gets MAX_SCORE points.
|
|
*/
|
|
score = MAX_SCORE - (MAX_SCORE * delta_size / base_size);
|
|
if (score < 0) return 0;
|
|
if (MAX_SCORE < score) return MAX_SCORE;
|
|
return score;
|
|
}
|
|
|
|
static void record_rename_pair(struct diff_queue_struct *renq,
|
|
int dst_index, int src_index, int score)
|
|
{
|
|
struct diff_filespec *one, *two, *src, *dst;
|
|
struct diff_filepair *dp;
|
|
|
|
if (rename_dst[dst_index].pair)
|
|
die("internal error: dst already matched.");
|
|
|
|
src = rename_src[src_index].one;
|
|
one = alloc_filespec(src->path);
|
|
fill_filespec(one, src->sha1, src->mode);
|
|
|
|
dst = rename_dst[dst_index].two;
|
|
two = alloc_filespec(dst->path);
|
|
fill_filespec(two, dst->sha1, dst->mode);
|
|
|
|
dp = diff_queue(renq, one, two);
|
|
dp->score = score;
|
|
dp->source_stays = rename_src[src_index].src_stays;
|
|
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_;
|
|
return b->score - a->score;
|
|
}
|
|
|
|
int diff_scoreopt_parse(const char *opt)
|
|
{
|
|
int diglen, num, scale, i;
|
|
if (opt[0] != '-' || (opt[1] != 'M' && opt[1] != 'C' && opt[1] != 'B'))
|
|
return -1; /* that is not a -M, -C nor -B option */
|
|
diglen = strspn(opt+2, "0123456789");
|
|
if (diglen == 0 || strlen(opt+2) != diglen)
|
|
return 0; /* use default */
|
|
sscanf(opt+2, "%d", &num);
|
|
for (i = 0, scale = 1; i < diglen; i++)
|
|
scale *= 10;
|
|
|
|
/* user says num divided by scale and we say internally that
|
|
* is MAX_SCORE * num / scale.
|
|
*/
|
|
return MAX_SCORE * num / scale;
|
|
}
|
|
|
|
void diffcore_rename(int detect_rename, int minimum_score)
|
|
{
|
|
struct diff_queue_struct *q = &diff_queued_diff;
|
|
struct diff_queue_struct renq, outq;
|
|
struct diff_score *mx;
|
|
int i, j;
|
|
int num_create, num_src, dst_cnt;
|
|
|
|
if (!minimum_score)
|
|
minimum_score = DEFAULT_RENAME_SCORE;
|
|
renq.queue = NULL;
|
|
renq.nr = renq.alloc = 0;
|
|
|
|
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
|
|
locate_rename_dst(p->two, 1);
|
|
else if (!DIFF_FILE_VALID(p->two))
|
|
register_rename_src(p->one, 0);
|
|
else if (detect_rename == DIFF_DETECT_COPY)
|
|
register_rename_src(p->one, 1);
|
|
}
|
|
if (rename_dst_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.
|
|
*/
|
|
for (i = 0; i < rename_dst_nr; i++) {
|
|
struct diff_filespec *two = rename_dst[i].two;
|
|
for (j = 0; j < rename_src_nr; j++) {
|
|
struct diff_filespec *one = rename_src[j].one;
|
|
if (!is_exact_match(one, two))
|
|
continue;
|
|
record_rename_pair(&renq, i, j, MAX_SCORE);
|
|
break; /* we are done with this entry */
|
|
}
|
|
}
|
|
diff_debug_queue("done detecting exact", &renq);
|
|
|
|
/* Have we run out the created file pool? If so we can avoid
|
|
* doing the delta matrix altogether.
|
|
*/
|
|
if (renq.nr == rename_dst_nr)
|
|
goto cleanup;
|
|
|
|
num_create = (rename_dst_nr - renq.nr);
|
|
num_src = rename_src_nr;
|
|
mx = xmalloc(sizeof(*mx) * num_create * num_src);
|
|
for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
|
|
int base = dst_cnt * num_src;
|
|
struct diff_filespec *two = rename_dst[i].two;
|
|
if (rename_dst[i].pair)
|
|
continue; /* dealt with exact match already. */
|
|
for (j = 0; j < rename_src_nr; j++) {
|
|
struct diff_filespec *one = rename_src[j].one;
|
|
struct diff_score *m = &mx[base+j];
|
|
m->src = j;
|
|
m->dst = i;
|
|
m->score = estimate_similarity(one, two,
|
|
minimum_score);
|
|
}
|
|
dst_cnt++;
|
|
}
|
|
/* cost matrix sorted by most to least similar pair */
|
|
qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
|
|
for (i = 0; i < num_create * num_src; i++) {
|
|
struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
|
|
if (dst->pair)
|
|
continue; /* already done, either exact or fuzzy. */
|
|
if (mx[i].score < minimum_score)
|
|
break; /* there is no more usable pair. */
|
|
record_rename_pair(&renq, mx[i].dst, mx[i].src, mx[i].score);
|
|
}
|
|
free(mx);
|
|
diff_debug_queue("done detecting fuzzy", &renq);
|
|
|
|
cleanup:
|
|
/* At this point, we have found some renames and copies and they
|
|
* are kept in renq. The original list is still in *q.
|
|
*/
|
|
outq.queue = NULL;
|
|
outq.nr = outq.alloc = 0;
|
|
for (i = 0; i < q->nr; i++) {
|
|
struct diff_filepair *p = q->queue[i];
|
|
struct diff_filepair *pair_to_free = NULL;
|
|
|
|
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, 0);
|
|
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 renq does
|
|
* not have a rename/copy to move p->one->path
|
|
* out.
|
|
*
|
|
* 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, 0);
|
|
if (dst && dst->pair)
|
|
/* counterpart is now rename/copy */
|
|
pair_to_free = p;
|
|
}
|
|
else {
|
|
for (j = 0; j < renq.nr; j++)
|
|
if (!strcmp(renq.queue[j]->one->path,
|
|
p->one->path))
|
|
break;
|
|
if (j < renq.nr)
|
|
/* 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(renq.queue);
|
|
free(q->queue);
|
|
*q = outq;
|
|
diff_debug_queue("done collapsing", q);
|
|
|
|
free(rename_dst);
|
|
rename_dst = NULL;
|
|
rename_dst_nr = rename_dst_alloc = 0;
|
|
free(rename_src);
|
|
rename_src = NULL;
|
|
rename_src_nr = rename_src_alloc = 0;
|
|
return;
|
|
}
|