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eede7b7d11
We find rename candidates by computing a fingerprint hash of each file, and then comparing those fingerprints. There are inherently O(n^2) comparisons, so it pays in CPU time to hoist the (rather expensive) computation of the fingerprint out of that loop (or to cache it once we have computed it once). Previously, we didn't keep the filespec information around because then we had the potential to consume a great deal of memory. However, instead of keeping all of the filespec data, we can instead just keep the fingerprint. This patch implements and uses diff_free_filespec_data_large to accomplish that goal. We also have to change estimate_similarity not to needlessly repopulate the filespec data when we already have the hash. Practical tests showed 4.5x speedup for a 10% memory usage increase. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
520 lines
14 KiB
C
520 lines
14 KiB
C
/*
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* Copyright (C) 2005 Junio C Hamano
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*/
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#include "cache.h"
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#include "diff.h"
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#include "diffcore.h"
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/* Table of rename/copy destinations */
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static struct diff_rename_dst {
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struct diff_filespec *two;
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struct diff_filepair *pair;
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} *rename_dst;
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static int rename_dst_nr, rename_dst_alloc;
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static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
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int insert_ok)
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{
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int first, last;
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first = 0;
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last = rename_dst_nr;
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while (last > first) {
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int next = (last + first) >> 1;
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struct diff_rename_dst *dst = &(rename_dst[next]);
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int cmp = strcmp(two->path, dst->two->path);
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if (!cmp)
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return dst;
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if (cmp < 0) {
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last = next;
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continue;
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}
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first = next+1;
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}
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/* not found */
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if (!insert_ok)
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return NULL;
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/* insert to make it at "first" */
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if (rename_dst_alloc <= rename_dst_nr) {
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rename_dst_alloc = alloc_nr(rename_dst_alloc);
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rename_dst = xrealloc(rename_dst,
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rename_dst_alloc * sizeof(*rename_dst));
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}
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rename_dst_nr++;
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if (first < rename_dst_nr)
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memmove(rename_dst + first + 1, rename_dst + first,
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(rename_dst_nr - first - 1) * sizeof(*rename_dst));
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rename_dst[first].two = alloc_filespec(two->path);
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fill_filespec(rename_dst[first].two, two->sha1, two->mode);
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rename_dst[first].pair = NULL;
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return &(rename_dst[first]);
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}
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/* Table of rename/copy src files */
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static struct diff_rename_src {
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struct diff_filespec *one;
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unsigned short score; /* to remember the break score */
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unsigned src_path_left : 1;
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} *rename_src;
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static int rename_src_nr, rename_src_alloc;
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static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
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int src_path_left,
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unsigned short score)
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{
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int first, last;
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first = 0;
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last = rename_src_nr;
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while (last > first) {
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int next = (last + first) >> 1;
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struct diff_rename_src *src = &(rename_src[next]);
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int cmp = strcmp(one->path, src->one->path);
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if (!cmp)
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return src;
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if (cmp < 0) {
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last = next;
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continue;
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}
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first = next+1;
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}
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/* insert to make it at "first" */
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if (rename_src_alloc <= rename_src_nr) {
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rename_src_alloc = alloc_nr(rename_src_alloc);
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rename_src = xrealloc(rename_src,
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rename_src_alloc * sizeof(*rename_src));
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}
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rename_src_nr++;
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if (first < rename_src_nr)
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memmove(rename_src + first + 1, rename_src + first,
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(rename_src_nr - first - 1) * sizeof(*rename_src));
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rename_src[first].one = one;
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rename_src[first].score = score;
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rename_src[first].src_path_left = src_path_left;
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return &(rename_src[first]);
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}
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static int is_exact_match(struct diff_filespec *src,
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struct diff_filespec *dst,
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int contents_too)
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{
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if (src->sha1_valid && dst->sha1_valid &&
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!hashcmp(src->sha1, dst->sha1))
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return 1;
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if (!contents_too)
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return 0;
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if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
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return 0;
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if (src->size != dst->size)
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return 0;
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if (src->sha1_valid && dst->sha1_valid)
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return !hashcmp(src->sha1, dst->sha1);
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if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
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return 0;
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if (src->size == dst->size &&
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!memcmp(src->data, dst->data, src->size))
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return 1;
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return 0;
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}
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static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
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{
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int src_len = strlen(src->path), dst_len = strlen(dst->path);
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while (src_len && dst_len) {
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char c1 = src->path[--src_len];
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char c2 = dst->path[--dst_len];
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if (c1 != c2)
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return 0;
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if (c1 == '/')
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return 1;
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}
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return (!src_len || src->path[src_len - 1] == '/') &&
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(!dst_len || dst->path[dst_len - 1] == '/');
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}
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struct diff_score {
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int src; /* index in rename_src */
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int dst; /* index in rename_dst */
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int score;
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int name_score;
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};
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static int estimate_similarity(struct diff_filespec *src,
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struct diff_filespec *dst,
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int minimum_score)
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{
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/* src points at a file that existed in the original tree (or
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* optionally a file in the destination tree) and dst points
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* at a newly created file. They may be quite similar, in which
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* case we want to say src is renamed to dst or src is copied into
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* dst, and then some edit has been applied to dst.
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*
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* Compare them and return how similar they are, representing
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* the score as an integer between 0 and MAX_SCORE.
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*
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* When there is an exact match, it is considered a better
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* match than anything else; the destination does not even
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* call into this function in that case.
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*/
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unsigned long max_size, delta_size, base_size, src_copied, literal_added;
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unsigned long delta_limit;
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int score;
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/* We deal only with regular files. Symlink renames are handled
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* only when they are exact matches --- in other words, no edits
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* after renaming.
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*/
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if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
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return 0;
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max_size = ((src->size > dst->size) ? src->size : dst->size);
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base_size = ((src->size < dst->size) ? src->size : dst->size);
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delta_size = max_size - base_size;
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/* We would not consider edits that change the file size so
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* drastically. delta_size must be smaller than
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* (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
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*
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* Note that base_size == 0 case is handled here already
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* and the final score computation below would not have a
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* divide-by-zero issue.
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*/
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if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
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return 0;
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if ((!src->cnt_data && diff_populate_filespec(src, 0))
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|| (!dst->cnt_data && diff_populate_filespec(dst, 0)))
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return 0; /* error but caught downstream */
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delta_limit = (unsigned long)
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(base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
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if (diffcore_count_changes(src, dst,
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&src->cnt_data, &dst->cnt_data,
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delta_limit,
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&src_copied, &literal_added))
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return 0;
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/* How similar are they?
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* what percentage of material in dst are from source?
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*/
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if (!dst->size)
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score = 0; /* should not happen */
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else
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score = (int)(src_copied * MAX_SCORE / max_size);
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return score;
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}
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static void record_rename_pair(int dst_index, int src_index, int score)
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{
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struct diff_filespec *one, *two, *src, *dst;
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struct diff_filepair *dp;
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if (rename_dst[dst_index].pair)
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die("internal error: dst already matched.");
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src = rename_src[src_index].one;
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one = alloc_filespec(src->path);
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fill_filespec(one, src->sha1, src->mode);
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dst = rename_dst[dst_index].two;
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two = alloc_filespec(dst->path);
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fill_filespec(two, dst->sha1, dst->mode);
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dp = diff_queue(NULL, one, two);
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dp->renamed_pair = 1;
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if (!strcmp(src->path, dst->path))
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dp->score = rename_src[src_index].score;
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else
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dp->score = score;
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dp->source_stays = rename_src[src_index].src_path_left;
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rename_dst[dst_index].pair = dp;
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}
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/*
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* We sort the rename similarity matrix with the score, in descending
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* order (the most similar first).
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*/
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static int score_compare(const void *a_, const void *b_)
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{
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const struct diff_score *a = a_, *b = b_;
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if (a->score == b->score)
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return b->name_score - a->name_score;
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return b->score - a->score;
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}
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static int compute_stays(struct diff_queue_struct *q,
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struct diff_filespec *one)
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{
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int i;
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for (i = 0; i < q->nr; i++) {
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struct diff_filepair *p = q->queue[i];
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if (strcmp(one->path, p->two->path))
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continue;
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if (DIFF_PAIR_RENAME(p)) {
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return 0; /* something else is renamed into this */
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}
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}
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return 1;
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}
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void diffcore_rename(struct diff_options *options)
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{
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int detect_rename = options->detect_rename;
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int minimum_score = options->rename_score;
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int rename_limit = options->rename_limit;
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struct diff_queue_struct *q = &diff_queued_diff;
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struct diff_queue_struct outq;
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struct diff_score *mx;
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int i, j, rename_count, contents_too;
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int num_create, num_src, dst_cnt;
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if (!minimum_score)
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minimum_score = DEFAULT_RENAME_SCORE;
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rename_count = 0;
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for (i = 0; i < q->nr; i++) {
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struct diff_filepair *p = q->queue[i];
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if (!DIFF_FILE_VALID(p->one)) {
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if (!DIFF_FILE_VALID(p->two))
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continue; /* unmerged */
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else if (options->single_follow &&
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strcmp(options->single_follow, p->two->path))
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continue; /* not interested */
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else
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locate_rename_dst(p->two, 1);
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}
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else if (!DIFF_FILE_VALID(p->two)) {
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/* If the source is a broken "delete", and
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* they did not really want to get broken,
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* that means the source actually stays.
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*/
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int stays = (p->broken_pair && !p->score);
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register_rename_src(p->one, stays, p->score);
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}
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else if (detect_rename == DIFF_DETECT_COPY)
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register_rename_src(p->one, 1, p->score);
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}
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if (rename_dst_nr == 0 || rename_src_nr == 0)
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goto cleanup; /* nothing to do */
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/*
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* This basically does a test for the rename matrix not
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* growing larger than a "rename_limit" square matrix, ie:
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*
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* rename_dst_nr * rename_src_nr > rename_limit * rename_limit
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*
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* but handles the potential overflow case specially (and we
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* assume at least 32-bit integers)
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*/
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if (rename_limit <= 0 || rename_limit > 32767)
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rename_limit = 32767;
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if (rename_dst_nr > rename_limit && rename_src_nr > rename_limit)
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goto cleanup;
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if (rename_dst_nr * rename_src_nr > rename_limit * rename_limit)
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goto cleanup;
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/* We really want to cull the candidates list early
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* with cheap tests in order to avoid doing deltas.
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* The first round matches up the up-to-date entries,
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* and then during the second round we try to match
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* cache-dirty entries as well.
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*/
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for (contents_too = 0; contents_too < 2; contents_too++) {
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for (i = 0; i < rename_dst_nr; i++) {
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struct diff_filespec *two = rename_dst[i].two;
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if (rename_dst[i].pair)
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continue; /* dealt with an earlier round */
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for (j = 0; j < rename_src_nr; j++) {
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int k;
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struct diff_filespec *one = rename_src[j].one;
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if (!is_exact_match(one, two, contents_too))
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continue;
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/* see if there is a basename match, too */
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for (k = j; k < rename_src_nr; k++) {
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one = rename_src[k].one;
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if (basename_same(one, two) &&
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is_exact_match(one, two,
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contents_too)) {
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j = k;
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break;
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}
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}
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record_rename_pair(i, j, (int)MAX_SCORE);
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rename_count++;
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break; /* we are done with this entry */
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}
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}
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}
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/* Have we run out the created file pool? If so we can avoid
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* doing the delta matrix altogether.
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*/
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if (rename_count == rename_dst_nr)
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goto cleanup;
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if (minimum_score == MAX_SCORE)
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goto cleanup;
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num_create = (rename_dst_nr - rename_count);
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num_src = rename_src_nr;
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mx = xmalloc(sizeof(*mx) * num_create * num_src);
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for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
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int base = dst_cnt * num_src;
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struct diff_filespec *two = rename_dst[i].two;
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if (rename_dst[i].pair)
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continue; /* dealt with exact match already. */
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for (j = 0; j < rename_src_nr; j++) {
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struct diff_filespec *one = rename_src[j].one;
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struct diff_score *m = &mx[base+j];
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m->src = j;
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m->dst = i;
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m->score = estimate_similarity(one, two,
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minimum_score);
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m->name_score = basename_same(one, two);
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diff_free_filespec_data_large(one);
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}
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/* We do not need the text anymore */
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diff_free_filespec_data_large(two);
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dst_cnt++;
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}
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/* cost matrix sorted by most to least similar pair */
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qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
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for (i = 0; i < num_create * num_src; i++) {
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struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
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if (dst->pair)
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continue; /* already done, either exact or fuzzy. */
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if (mx[i].score < minimum_score)
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break; /* there is no more usable pair. */
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record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
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rename_count++;
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}
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free(mx);
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cleanup:
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/* At this point, we have found some renames and copies and they
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* are recorded in rename_dst. The original list is still in *q.
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*/
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outq.queue = NULL;
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outq.nr = outq.alloc = 0;
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for (i = 0; i < q->nr; i++) {
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struct diff_filepair *p = q->queue[i];
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struct diff_filepair *pair_to_free = NULL;
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if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
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/*
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* Creation
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*
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* We would output this create record if it has
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* not been turned into a rename/copy already.
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*/
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struct diff_rename_dst *dst =
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locate_rename_dst(p->two, 0);
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if (dst && dst->pair) {
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diff_q(&outq, dst->pair);
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pair_to_free = p;
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}
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else
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/* no matching rename/copy source, so
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* record this as a creation.
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*/
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diff_q(&outq, p);
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}
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else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
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/*
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* Deletion
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*
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* We would output this delete record if:
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*
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* (1) this is a broken delete and the counterpart
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* broken create remains in the output; or
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* (2) this is not a broken delete, and rename_dst
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* does not have a rename/copy to move p->one->path
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* out of existence.
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*
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* Otherwise, the counterpart broken create
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* has been turned into a rename-edit; or
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* delete did not have a matching create to
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* begin with.
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*/
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if (DIFF_PAIR_BROKEN(p)) {
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/* broken delete */
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struct diff_rename_dst *dst =
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locate_rename_dst(p->one, 0);
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if (dst && dst->pair)
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/* counterpart is now rename/copy */
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pair_to_free = p;
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}
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else {
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for (j = 0; j < rename_dst_nr; j++) {
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if (!rename_dst[j].pair)
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continue;
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if (strcmp(rename_dst[j].pair->
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one->path,
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p->one->path))
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continue;
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break;
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}
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if (j < rename_dst_nr)
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/* this path remains */
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pair_to_free = p;
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}
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if (pair_to_free)
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;
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else
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diff_q(&outq, p);
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}
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else if (!diff_unmodified_pair(p))
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/* all the usual ones need to be kept */
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diff_q(&outq, p);
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else
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/* no need to keep unmodified pairs */
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pair_to_free = p;
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if (pair_to_free)
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diff_free_filepair(pair_to_free);
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}
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diff_debug_queue("done copying original", &outq);
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|
|
free(q->queue);
|
|
*q = outq;
|
|
diff_debug_queue("done collapsing", q);
|
|
|
|
/* We need to see which rename source really stays here;
|
|
* earlier we only checked if the path is left in the result,
|
|
* but even if a path remains in the result, if that is coming
|
|
* from copying something else on top of it, then the original
|
|
* source is lost and does not stay.
|
|
*/
|
|
for (i = 0; i < q->nr; i++) {
|
|
struct diff_filepair *p = q->queue[i];
|
|
if (DIFF_PAIR_RENAME(p) && p->source_stays) {
|
|
/* If one appears as the target of a rename-copy,
|
|
* then mark p->source_stays = 0; otherwise
|
|
* leave it as is.
|
|
*/
|
|
p->source_stays = compute_stays(q, p->one);
|
|
}
|
|
}
|
|
|
|
for (i = 0; i < rename_dst_nr; i++) {
|
|
diff_free_filespec_data(rename_dst[i].two);
|
|
free(rename_dst[i].two);
|
|
}
|
|
|
|
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;
|
|
}
|