git/diffcore-rename.c
Junio C Hamano 15d061b435 [PATCH] Fix the way diffcore-rename records unremoved source.
Earier version of diffcore-rename used to keep unmodified
filepair in its output so that the last stage of the processing
that tells renames from copies can make all of rename/copy to
copies.  However this had a bad interaction with other diffcore
filters that wanted to run after diffcore-rename, in that such
unmodified filepair must be retained for proper distinction
between renames and copies to happen.

This patch fixes the problem by changing the way diffcore-rename
records the information needed to distinguish "all are copies"
case and "the last one is a rename" case.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-29 11:17:43 -07:00

367 lines
10 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) || diff_populate_filespec(dst))
/* this is an error but will be caught downstream */
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 10000, except
* where they match exactly it is considered better than anything
* else.
*/
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;
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 ? : 1; /* make sure it is at least 1 */
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'))
return -1; /* that is not a -M nor -C 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_MINIMUM_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_rename_dst *dst = locate_rename_dst(p->two, 0);
struct diff_filepair *pair_to_free = NULL;
if (dst) {
/* creation */
if (dst->pair) {
/* renq has rename/copy to produce
* this file already, so we do not
* emit the creation record in the
* output.
*/
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_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;
}