Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 684 insertions, 0 deletions

diff --git a/diffcore-rename.c b/diffcore-rename.c
new file mode 100644
index 000000000000..9624864858dc
--- /dev/null
+++ b/diffcore-rename.c
@@ -0,0 +1,684 @@
+/*
+ * 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"
+
+/* 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 = first + ((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)
+		MOVE_ARRAY(rename_dst + first + 1, rename_dst + first,
+			   rename_dst_nr - first - 1);
+	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 = first + ((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)
+		MOVE_ARRAY(rename_src + first + 1, rename_src + first,
+			   rename_src_nr - first - 1);
+	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 repository *r,
+			       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(r, src, CHECK_SIZE_ONLY))
+		return 0;
+	if (!dst->cnt_data &&
+	    diff_populate_filespec(r, 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(r, src, 0))
+		return 0;
+	if (!dst->cnt_data && diff_populate_filespec(r, dst, 0))
+		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_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 repository *r,
+				  struct diff_filespec *filespec)
+{
+	if (!filespec->oid_valid) {
+		if (diff_populate_filespec(r, filespec, 0))
+			return 0;
+		hash_object_file(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].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(options->repo, target),
+				  NULL);
+	for (; p; p = hashmap_get_next(srcs, p)) {
+		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, hash_filespec(r, 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(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_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
+	 */
+	if (rename_limit <= 0)
+		rename_limit = 32767;
+	if ((num_create <= rename_limit || num_src <= rename_limit) &&
+	    ((uint64_t)num_create * (uint64_t)num_src
+	     <= (uint64_t)rename_limit * (uint64_t)rename_limit))
+		return 0;
+
+	options->needed_rename_limit =
+		num_src > num_create ? num_src : num_create;
+
+	/* 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 (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) &&
+	    ((uint64_t)num_create * (uint64_t)num_src
+	     <= (uint64_t)rename_limit * (uint64_t)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 (!options->flags.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 (!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 (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"),
+				(uint64_t)rename_dst_nr * (uint64_t)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(options->repo,
+							     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, (uint64_t)(i+1)*(uint64_t)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;
+}