expose a helper function peel_to_type().
[gitweb.git] / diffcore-rename.c
index 142e5376dd741377c311075816f139a0949ee82f..3d377251bef8ea843b7a7fa41f98d611daecbcc1 100644 (file)
@@ -4,6 +4,7 @@
 #include "cache.h"
 #include "diff.h"
 #include "diffcore.h"
+#include "hash.h"
 
 /* Table of rename/copy destinations */
 
@@ -55,12 +56,10 @@ static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
 static struct diff_rename_src {
        struct diff_filespec *one;
        unsigned short score; /* to remember the break score */
-       unsigned src_path_left : 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_path_left,
                                                   unsigned short score)
 {
        int first, last;
@@ -92,33 +91,9 @@ static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
                        (rename_src_nr - first - 1) * sizeof(*rename_src));
        rename_src[first].one = one;
        rename_src[first].score = score;
-       rename_src[first].src_path_left = src_path_left;
        return &(rename_src[first]);
 }
 
-static int is_exact_match(struct diff_filespec *src,
-                         struct diff_filespec *dst,
-                         int contents_too)
-{
-       if (src->sha1_valid && dst->sha1_valid &&
-           !hashcmp(src->sha1, dst->sha1))
-               return 1;
-       if (!contents_too)
-               return 0;
-       if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
-               return 0;
-       if (src->size != dst->size)
-               return 0;
-       if (src->sha1_valid && dst->sha1_valid)
-           return !hashcmp(src->sha1, dst->sha1);
-       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;
-}
-
 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
 {
        int src_len = strlen(src->path), dst_len = strlen(dst->path);
@@ -169,6 +144,20 @@ static int estimate_similarity(struct diff_filespec *src,
        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, 0))
+               return 0;
+       if (!dst->cnt_data && diff_populate_filespec(dst, 0))
+               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;
@@ -184,11 +173,6 @@ static int estimate_similarity(struct diff_filespec *src,
        if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
                return 0;
 
-       if ((!src->cnt_data && diff_populate_filespec(src, 0))
-               || (!dst->cnt_data && diff_populate_filespec(dst, 0)))
-               return 0; /* error but caught downstream */
-
-
        delta_limit = (unsigned long)
                (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
        if (diffcore_count_changes(src, dst,
@@ -209,27 +193,25 @@ static int estimate_similarity(struct diff_filespec *src,
 
 static void record_rename_pair(int dst_index, int src_index, int score)
 {
-       struct diff_filespec *one, *two, *src, *dst;
+       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].one;
-       one = alloc_filespec(src->path);
-       fill_filespec(one, src->sha1, src->mode);
+       src->rename_used++;
+       src->count++;
 
        dst = rename_dst[dst_index].two;
-       two = alloc_filespec(dst->path);
-       fill_filespec(two, dst->sha1, dst->mode);
+       dst->count++;
 
-       dp = diff_queue(NULL, one, two);
+       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;
-       dp->source_stays = rename_src[src_index].src_path_left;
        rename_dst[dst_index].pair = dp;
 }
 
@@ -247,19 +229,162 @@ static int score_compare(const void *a_, const void *b_)
        return b->score - a->score;
 }
 
-static int compute_stays(struct diff_queue_struct *q,
-                        struct diff_filespec *one)
+struct file_similarity {
+       int src_dst, index;
+       struct diff_filespec *filespec;
+       struct file_similarity *next;
+};
+
+static int find_identical_files(struct file_similarity *src,
+                               struct file_similarity *dst)
 {
-       int i;
-       for (i = 0; i < q->nr; i++) {
-               struct diff_filepair *p = q->queue[i];
-               if (strcmp(one->path, p->two->path))
-                       continue;
-               if (DIFF_PAIR_RENAME(p)) {
-                       return 0; /* something else is renamed into this */
+       int renames = 0;
+
+       /*
+        * Walk over all the destinations ...
+        */
+       do {
+               struct diff_filespec *target = dst->filespec;
+               struct file_similarity *p, *best;
+               int i = 100, best_score = -1;
+
+               /*
+                * .. to find the best source match
+                */
+               best = NULL;
+               for (p = src; p; p = p->next) {
+                       int score;
+                       struct diff_filespec *source = p->filespec;
+
+                       /* False hash collission? */
+                       if (hashcmp(source->sha1, target->sha1))
+                               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;
+                       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++;
+               }
+       } while ((dst = dst->next) != NULL);
+       return renames;
+}
+
+static void free_similarity_list(struct file_similarity *p)
+{
+       while (p) {
+               struct file_similarity *entry = p;
+               p = p->next;
+               free(entry);
+       }
+}
+
+static int find_same_files(void *ptr)
+{
+       int ret;
+       struct file_similarity *p = ptr;
+       struct file_similarity *src = NULL, *dst = NULL;
+
+       /* Split the hash list up into sources and destinations */
+       do {
+               struct file_similarity *entry = p;
+               p = p->next;
+               if (entry->src_dst < 0) {
+                       entry->next = src;
+                       src = entry;
+               } else {
+                       entry->next = dst;
+                       dst = entry;
+               }
+       } while (p);
+
+       /*
+        * If we have both sources *and* destinations, see if
+        * we can match them up
+        */
+       ret = (src && dst) ? find_identical_files(src, dst) : 0;
+
+       /* Free the hashes and return the number of renames found */
+       free_similarity_list(src);
+       free_similarity_list(dst);
+       return ret;
+}
+
+static unsigned int hash_filespec(struct diff_filespec *filespec)
+{
+       unsigned int hash;
+       if (!filespec->sha1_valid) {
+               if (diff_populate_filespec(filespec, 0))
+                       return 0;
+               hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
+       }
+       memcpy(&hash, filespec->sha1, sizeof(hash));
+       return hash;
+}
+
+static void insert_file_table(struct hash_table *table, int src_dst, int index, struct diff_filespec *filespec)
+{
+       void **pos;
+       unsigned int hash;
+       struct file_similarity *entry = xmalloc(sizeof(*entry));
+
+       entry->src_dst = src_dst;
+       entry->index = index;
+       entry->filespec = filespec;
+       entry->next = NULL;
+
+       hash = hash_filespec(filespec);
+       pos = insert_hash(hash, entry, table);
+
+       /* We already had an entry there? */
+       if (pos) {
+               entry->next = *pos;
+               *pos = entry;
        }
-       return 1;
+}
+
+/*
+ * 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(void)
+{
+       int i;
+       struct hash_table file_table;
+
+       init_hash(&file_table);
+       for (i = 0; i < rename_src_nr; i++)
+               insert_file_table(&file_table, -1, i, rename_src[i].one);
+
+       for (i = 0; i < rename_dst_nr; i++)
+               insert_file_table(&file_table, 1, i, rename_dst[i].two);
+
+       /* Find the renames */
+       i = for_each_hash(&file_table, find_same_files);
+
+       /* .. and free the hash data structure */
+       free_hash(&file_table);
+
+       return i;
 }
 
 void diffcore_rename(struct diff_options *options)
@@ -270,12 +395,11 @@ void diffcore_rename(struct diff_options *options)
        struct diff_queue_struct *q = &diff_queued_diff;
        struct diff_queue_struct outq;
        struct diff_score *mx;
-       int i, j, rename_count, contents_too;
+       int i, j, rename_count;
        int num_create, num_src, dst_cnt;
 
        if (!minimum_score)
                minimum_score = DEFAULT_RENAME_SCORE;
-       rename_count = 0;
 
        for (i = 0; i < q->nr; i++) {
                struct diff_filepair *p = q->queue[i];
@@ -289,81 +413,66 @@ void diffcore_rename(struct diff_options *options)
                                locate_rename_dst(p->two, 1);
                }
                else if (!DIFF_FILE_VALID(p->two)) {
-                       /* If the source is a broken "delete", and
+                       /*
+                        * 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->one, p->score);
+               }
+               else if (detect_rename == DIFF_DETECT_COPY) {
+                       /*
+                        * Increment the "rename_used" score by
+                        * one, to indicate ourselves as a user.
                         */
-                       int stays = (p->broken_pair && !p->score);
-                       register_rename_src(p->one, stays, p->score);
+                       p->one->rename_used++;
+                       register_rename_src(p->one, p->score);
                }
-               else if (detect_rename == DIFF_DETECT_COPY)
-                       register_rename_src(p->one, 1, p->score);
        }
        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();
+
+       /* 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);
+       num_src = rename_src_nr;
+
+       /* All done? */
+       if (!num_create)
+               goto cleanup;
+
        /*
         * This basically does a test for the rename matrix not
         * growing larger than a "rename_limit" square matrix, ie:
         *
-        *    rename_dst_nr * rename_src_nr > rename_limit * rename_limit
+        *    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 (rename_dst_nr > rename_limit && rename_src_nr > rename_limit)
+       if (num_create > rename_limit && num_src > rename_limit)
                goto cleanup;
-       if (rename_dst_nr * rename_src_nr > rename_limit * rename_limit)
+       if (num_create * num_src > rename_limit * rename_limit)
                goto cleanup;
 
-       /* We really want to cull the candidates list early
-        * with cheap tests in order to avoid doing deltas.
-        * 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.
-        */
-       for (contents_too = 0; contents_too < 2; contents_too++) {
-               for (i = 0; i < rename_dst_nr; i++) {
-                       struct diff_filespec *two = rename_dst[i].two;
-                       if (rename_dst[i].pair)
-                               continue; /* dealt with an earlier round */
-                       for (j = 0; j < rename_src_nr; j++) {
-                               int k;
-                               struct diff_filespec *one = rename_src[j].one;
-                               if (!is_exact_match(one, two, contents_too))
-                                       continue;
-
-                               /* see if there is a basename match, too */
-                               for (k = j; k < rename_src_nr; k++) {
-                                       one = rename_src[k].one;
-                                       if (basename_same(one, two) &&
-                                               is_exact_match(one, two,
-                                                       contents_too)) {
-                                               j = k;
-                                               break;
-                                       }
-                               }
-
-                               record_rename_pair(i, j, (int)MAX_SCORE);
-                               rename_count++;
-                               break; /* we are done with this entry */
-                       }
-               }
-       }
-
-       /* Have we run out the created file pool?  If so we can avoid
-        * doing the delta matrix altogether.
-        */
-       if (rename_count == rename_dst_nr)
-               goto cleanup;
-
-       if (minimum_score == MAX_SCORE)
-               goto cleanup;
-
-       num_create = (rename_dst_nr - rename_count);
-       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;
@@ -386,6 +495,19 @@ void diffcore_rename(struct diff_options *options)
        }
        /* 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];
+               struct diff_filespec *src;
+               if (dst->pair)
+                       continue; /* already done, either exact or fuzzy. */
+               if (mx[i].score < minimum_score)
+                       break; /* there is no more usable pair. */
+               src = rename_src[mx[i].src].one;
+               if (src->rename_used)
+                       continue;
+               record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
+               rename_count++;
+       }
        for (i = 0; i < num_create * num_src; i++) {
                struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
                if (dst->pair)
@@ -452,16 +574,7 @@ void diffcore_rename(struct diff_options *options)
                                        pair_to_free = p;
                        }
                        else {
-                               for (j = 0; j < rename_dst_nr; j++) {
-                                       if (!rename_dst[j].pair)
-                                               continue;
-                                       if (strcmp(rename_dst[j].pair->
-                                                  one->path,
-                                                  p->one->path))
-                                               continue;
-                                       break;
-                               }
-                               if (j < rename_dst_nr)
+                               if (p->one->rename_used)
                                        /* this path remains */
                                        pair_to_free = p;
                        }
@@ -487,27 +600,8 @@ void diffcore_rename(struct diff_options *options)
        *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);
-       }
+       for (i = 0; i < rename_dst_nr; i++)
+               free_filespec(rename_dst[i].two);
 
        free(rename_dst);
        rename_dst = NULL;