pack-objects: implement bitmap writing

[thirdparty/git.git] / pack-bitmap.c

diff --git a/pack-bitmap.c b/pack-bitmap.c
index 33e748273ad71c0ddf49bd631522ae0662844ae7..82090a67413ad7cc10bbcd37faf6ed549bfc8706 100644 (file)
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -968,3 +968,95 @@ void test_bitmap_walk(struct rev_info *revs)
        else
                fprintf(stderr, "Mismatch!\n");
 }
+
+static int rebuild_bitmap(uint32_t *reposition,
+                         struct ewah_bitmap *source,
+                         struct bitmap *dest)
+{
+       uint32_t pos = 0;
+       struct ewah_iterator it;
+       eword_t word;
+
+       ewah_iterator_init(&it, source);
+
+       while (ewah_iterator_next(&word, &it)) {
+               uint32_t offset, bit_pos;
+
+               for (offset = 0; offset < BITS_IN_WORD; ++offset) {
+                       if ((word >> offset) == 0)
+                               break;
+
+                       offset += ewah_bit_ctz64(word >> offset);
+
+                       bit_pos = reposition[pos + offset];
+                       if (bit_pos > 0)
+                               bitmap_set(dest, bit_pos - 1);
+                       else /* can't reuse, we don't have the object */
+                               return -1;
+               }
+
+               pos += BITS_IN_WORD;
+       }
+       return 0;
+}
+
+int rebuild_existing_bitmaps(struct packing_data *mapping,
+                            khash_sha1 *reused_bitmaps,
+                            int show_progress)
+{
+       uint32_t i, num_objects;
+       uint32_t *reposition;
+       struct bitmap *rebuild;
+       struct stored_bitmap *stored;
+       struct progress *progress = NULL;
+
+       khiter_t hash_pos;
+       int hash_ret;
+
+       if (prepare_bitmap_git() < 0)
+               return -1;
+
+       num_objects = bitmap_git.pack->num_objects;
+       reposition = xcalloc(num_objects, sizeof(uint32_t));
+
+       for (i = 0; i < num_objects; ++i) {
+               const unsigned char *sha1;
+               struct revindex_entry *entry;
+               struct object_entry *oe;
+
+               entry = &bitmap_git.reverse_index->revindex[i];
+               sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
+               oe = packlist_find(mapping, sha1, NULL);
+
+               if (oe)
+                       reposition[i] = oe->in_pack_pos + 1;
+       }
+
+       rebuild = bitmap_new();
+       i = 0;
+
+       if (show_progress)
+               progress = start_progress("Reusing bitmaps", 0);
+
+       kh_foreach_value(bitmap_git.bitmaps, stored, {
+               if (stored->flags & BITMAP_FLAG_REUSE) {
+                       if (!rebuild_bitmap(reposition,
+                                           lookup_stored_bitmap(stored),
+                                           rebuild)) {
+                               hash_pos = kh_put_sha1(reused_bitmaps,
+                                                      stored->sha1,
+                                                      &hash_ret);
+                               kh_value(reused_bitmaps, hash_pos) =
+                                       bitmap_to_ewah(rebuild);
+                       }
+                       bitmap_reset(rebuild);
+                       display_progress(progress, ++i);
+               }
+       });
+
+       stop_progress(&progress);
+
+       free(reposition);
+       bitmap_free(rebuild);
+       return 0;
+}