split-index.c

   1 #include "cache.h"
   2 #include "split-index.h"
   3 #include "ewah/ewok.h"
   4
   5 struct split_index *init_split_index(struct index_state *istate)
   6 {
   7         if (!istate->split_index) {
   8                 istate->split_index = xcalloc(1, sizeof(*istate->split_index));
   9                 istate->split_index->refcount = 1;
  10         }
  11         return istate->split_index;
  12 }
  13
  14 int read_link_extension(struct index_state *istate,
  15                          const void *data_, unsigned long sz)
  16 {
  17         const unsigned char *data = data_;
  18         struct split_index *si;
  19         int ret;
  20
  21         if (sz < 20)
  22                 return error("corrupt link extension (too short)");
  23         si = init_split_index(istate);
  24         hashcpy(si->base_sha1, data);
  25         data += 20;
  26         sz -= 20;
  27         if (!sz)
  28                 return 0;
  29         si->delete_bitmap = ewah_new();
  30         ret = ewah_read_mmap(si->delete_bitmap, data, sz);
  31         if (ret < 0)
  32                 return error("corrupt delete bitmap in link extension");
  33         data += ret;
  34         sz -= ret;
  35         si->replace_bitmap = ewah_new();
  36         ret = ewah_read_mmap(si->replace_bitmap, data, sz);
  37         if (ret < 0)
  38                 return error("corrupt replace bitmap in link extension");
  39         if (ret != sz)
  40                 return error("garbage at the end of link extension");
  41         return 0;
  42 }
  43
  44 int write_link_extension(struct strbuf *sb,
  45                          struct index_state *istate)
  46 {
  47         struct split_index *si = istate->split_index;
  48         strbuf_add(sb, si->base_sha1, 20);
  49         if (!si->delete_bitmap && !si->replace_bitmap)
  50                 return 0;
  51         ewah_serialize_strbuf(si->delete_bitmap, sb);
  52         ewah_serialize_strbuf(si->replace_bitmap, sb);
  53         return 0;
  54 }
  55
  56 static void mark_base_index_entries(struct index_state *base)
  57 {
  58         int i;
  59         /*
  60          * To keep track of the shared entries between
  61          * istate->base->cache[] and istate->cache[], base entry
  62          * position is stored in each base entry. All positions start
  63          * from 1 instead of 0, which is reserved to say "this is a new
  64          * entry".
  65          */
  66         for (i = 0; i < base->cache_nr; i++)
  67                 base->cache[i]->index = i + 1;
  68 }
  69
  70 void move_cache_to_base_index(struct index_state *istate)
  71 {
  72         struct split_index *si = istate->split_index;
  73         int i;
  74
  75         /*
  76          * If "si" is shared with another index_state (e.g. by
  77          * unpack-trees code), we will need to duplicate split_index
  78          * struct. It's not happening now though, luckily.
  79          */
  80         assert(si->refcount <= 1);
  81
  82         unshare_split_index(istate, 0);
  83         if (si->base) {
  84                 discard_index(si->base);
  85                 free(si->base);
  86         }
  87         si->base = xcalloc(1, sizeof(*si->base));
  88         si->base->version = istate->version;
  89         /* zero timestamp disables racy test in ce_write_index() */
  90         si->base->timestamp = istate->timestamp;
  91         ALLOC_GROW(si->base->cache, istate->cache_nr, si->base->cache_alloc);
  92         si->base->cache_nr = istate->cache_nr;
  93         COPY_ARRAY(si->base->cache, istate->cache, istate->cache_nr);
  94         mark_base_index_entries(si->base);
  95         for (i = 0; i < si->base->cache_nr; i++)
  96                 si->base->cache[i]->ce_flags &= ~CE_UPDATE_IN_BASE;
  97 }
  98
  99 static void mark_entry_for_delete(size_t pos, void *data)
 100 {
 101         struct index_state *istate = data;
 102         if (pos >= istate->cache_nr)
 103                 die("position for delete %d exceeds base index size %d",
 104                     (int)pos, istate->cache_nr);
 105         istate->cache[pos]->ce_flags |= CE_REMOVE;
 106         istate->split_index->nr_deletions = 1;
 107 }
 108
 109 static void replace_entry(size_t pos, void *data)
 110 {
 111         struct index_state *istate = data;
 112         struct split_index *si = istate->split_index;
 113         struct cache_entry *dst, *src;
 114
 115         if (pos >= istate->cache_nr)
 116                 die("position for replacement %d exceeds base index size %d",
 117                     (int)pos, istate->cache_nr);
 118         if (si->nr_replacements >= si->saved_cache_nr)
 119                 die("too many replacements (%d vs %d)",
 120                     si->nr_replacements, si->saved_cache_nr);
 121         dst = istate->cache[pos];
 122         if (dst->ce_flags & CE_REMOVE)
 123                 die("entry %d is marked as both replaced and deleted",
 124                     (int)pos);
 125         src = si->saved_cache[si->nr_replacements];
 126         if (ce_namelen(src))
 127                 die("corrupt link extension, entry %d should have "
 128                     "zero length name", (int)pos);
 129         src->index = pos + 1;
 130         src->ce_flags |= CE_UPDATE_IN_BASE;
 131         src->ce_namelen = dst->ce_namelen;
 132         copy_cache_entry(dst, src);
 133         free(src);
 134         si->nr_replacements++;
 135 }
 136
 137 void merge_base_index(struct index_state *istate)
 138 {
 139         struct split_index *si = istate->split_index;
 140         unsigned int i;
 141
 142         mark_base_index_entries(si->base);
 143
 144         si->saved_cache     = istate->cache;
 145         si->saved_cache_nr  = istate->cache_nr;
 146         istate->cache_nr    = si->base->cache_nr;
 147         istate->cache       = NULL;
 148         istate->cache_alloc = 0;
 149         ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);
 150         COPY_ARRAY(istate->cache, si->base->cache, istate->cache_nr);
 151
 152         si->nr_deletions = 0;
 153         si->nr_replacements = 0;
 154         ewah_each_bit(si->replace_bitmap, replace_entry, istate);
 155         ewah_each_bit(si->delete_bitmap, mark_entry_for_delete, istate);
 156         if (si->nr_deletions)
 157                 remove_marked_cache_entries(istate);
 158
 159         for (i = si->nr_replacements; i < si->saved_cache_nr; i++) {
 160                 if (!ce_namelen(si->saved_cache[i]))
 161                         die("corrupt link extension, entry %d should "
 162                             "have non-zero length name", i);
 163                 add_index_entry(istate, si->saved_cache[i],
 164                                 ADD_CACHE_OK_TO_ADD |
 165                                 ADD_CACHE_KEEP_CACHE_TREE |
 166                                 /*
 167                                  * we may have to replay what
 168                                  * merge-recursive.c:update_stages()
 169                                  * does, which has this flag on
 170                                  */
 171                                 ADD_CACHE_SKIP_DFCHECK);
 172                 si->saved_cache[i] = NULL;
 173         }
 174
 175         ewah_free(si->delete_bitmap);
 176         ewah_free(si->replace_bitmap);
 177         free(si->saved_cache);
 178         si->delete_bitmap  = NULL;
 179         si->replace_bitmap = NULL;
 180         si->saved_cache    = NULL;
 181         si->saved_cache_nr = 0;
 182 }
 183
 184 void prepare_to_write_split_index(struct index_state *istate)
 185 {
 186         struct split_index *si = init_split_index(istate);
 187         struct cache_entry **entries = NULL, *ce;
 188         int i, nr_entries = 0, nr_alloc = 0;
 189
 190         si->delete_bitmap = ewah_new();
 191         si->replace_bitmap = ewah_new();
 192
 193         if (si->base) {
 194                 /* Go through istate->cache[] and mark CE_MATCHED to
 195                  * entry with positive index. We'll go through
 196                  * base->cache[] later to delete all entries in base
 197                  * that are not marked with either CE_MATCHED or
 198                  * CE_UPDATE_IN_BASE. If istate->cache[i] is a
 199                  * duplicate, deduplicate it.
 200                  */
 201                 for (i = 0; i < istate->cache_nr; i++) {
 202                         struct cache_entry *base;
 203                         /* namelen is checked separately */
 204                         const unsigned int ondisk_flags =
 205                                 CE_STAGEMASK | CE_VALID | CE_EXTENDED_FLAGS;
 206                         unsigned int ce_flags, base_flags, ret;
 207                         ce = istate->cache[i];
 208                         if (!ce->index)
 209                                 continue;
 210                         if (ce->index > si->base->cache_nr) {
 211                                 ce->index = 0;
 212                                 continue;
 213                         }
 214                         ce->ce_flags |= CE_MATCHED; /* or "shared" */
 215                         base = si->base->cache[ce->index - 1];
 216                         if (ce == base)
 217                                 continue;
 218                         if (ce->ce_namelen != base->ce_namelen ||
 219                             strcmp(ce->name, base->name)) {
 220                                 ce->index = 0;
 221                                 continue;
 222                         }
 223                         ce_flags = ce->ce_flags;
 224                         base_flags = base->ce_flags;
 225                         /* only on-disk flags matter */
 226                         ce->ce_flags   &= ondisk_flags;
 227                         base->ce_flags &= ondisk_flags;
 228                         ret = memcmp(&ce->ce_stat_data, &base->ce_stat_data,
 229                                      offsetof(struct cache_entry, name) -
 230                                      offsetof(struct cache_entry, ce_stat_data));
 231                         ce->ce_flags = ce_flags;
 232                         base->ce_flags = base_flags;
 233                         if (ret)
 234                                 ce->ce_flags |= CE_UPDATE_IN_BASE;
 235                         free(base);
 236                         si->base->cache[ce->index - 1] = ce;
 237                 }
 238                 for (i = 0; i < si->base->cache_nr; i++) {
 239                         ce = si->base->cache[i];
 240                         if ((ce->ce_flags & CE_REMOVE) ||
 241                             !(ce->ce_flags & CE_MATCHED))
 242                                 ewah_set(si->delete_bitmap, i);
 243                         else if (ce->ce_flags & CE_UPDATE_IN_BASE) {
 244                                 ewah_set(si->replace_bitmap, i);
 245                                 ce->ce_flags |= CE_STRIP_NAME;
 246                                 ALLOC_GROW(entries, nr_entries+1, nr_alloc);
 247                                 entries[nr_entries++] = ce;
 248                         }
 249                 }
 250         }
 251
 252         for (i = 0; i < istate->cache_nr; i++) {
 253                 ce = istate->cache[i];
 254                 if ((!si->base || !ce->index) && !(ce->ce_flags & CE_REMOVE)) {
 255                         assert(!(ce->ce_flags & CE_STRIP_NAME));
 256                         ALLOC_GROW(entries, nr_entries+1, nr_alloc);
 257                         entries[nr_entries++] = ce;
 258                 }
 259                 ce->ce_flags &= ~CE_MATCHED;
 260         }
 261
 262         /*
 263          * take cache[] out temporarily, put entries[] in its place
 264          * for writing
 265          */
 266         si->saved_cache = istate->cache;
 267         si->saved_cache_nr = istate->cache_nr;
 268         istate->cache = entries;
 269         istate->cache_nr = nr_entries;
 270 }
 271
 272 void finish_writing_split_index(struct index_state *istate)
 273 {
 274         struct split_index *si = init_split_index(istate);
 275
 276         ewah_free(si->delete_bitmap);
 277         ewah_free(si->replace_bitmap);
 278         si->delete_bitmap = NULL;
 279         si->replace_bitmap = NULL;
 280         free(istate->cache);
 281         istate->cache = si->saved_cache;
 282         istate->cache_nr = si->saved_cache_nr;
 283 }
 284
 285 void unshare_split_index(struct index_state *istate, int discard)
 286 {
 287         struct split_index *si = istate->split_index;
 288         int i;
 289
 290         if (!si || !si->base)
 291                 return;
 292
 293         for (i = 0; i < istate->cache_nr; i++) {
 294                 struct cache_entry *ce = istate->cache[i];
 295                 struct cache_entry *new = NULL;
 296
 297                 if (!ce->index ||
 298                     ce->index > si->base->cache_nr ||
 299                     ce != si->base->cache[ce->index - 1])
 300                         continue;
 301
 302                 if (!discard) {
 303                         int len = ce_namelen(ce);
 304                         new = xcalloc(1, cache_entry_size(len));
 305                         copy_cache_entry(new, ce);
 306                         memcpy(new->name, ce->name, len);
 307                         new->index = 0;
 308                 }
 309                 istate->cache[i] = new;
 310         }
 311 }
 312
 313
 314 void discard_split_index(struct index_state *istate)
 315 {
 316         struct split_index *si = istate->split_index;
 317         if (!si)
 318                 return;
 319         unshare_split_index(istate, 0);
 320         istate->split_index = NULL;
 321         si->refcount--;
 322         if (si->refcount)
 323                 return;
 324         if (si->base) {
 325                 discard_index(si->base);
 326                 free(si->base);
 327         }
 328         free(si);
 329 }
 330
 331 void save_or_free_index_entry(struct index_state *istate, struct cache_entry *ce)
 332 {
 333         if (ce->index &&
 334             istate->split_index &&
 335             istate->split_index->base &&
 336             ce->index <= istate->split_index->base->cache_nr &&
 337             ce == istate->split_index->base->cache[ce->index - 1])
 338                 ce->ce_flags |= CE_REMOVE;
 339         else
 340                 free(ce);
 341 }
 342
 343 void replace_index_entry_in_base(struct index_state *istate,
 344                                  struct cache_entry *old,
 345                                  struct cache_entry *new)
 346 {
 347         if (old->index &&
 348             istate->split_index &&
 349             istate->split_index->base &&
 350             old->index <= istate->split_index->base->cache_nr) {
 351                 new->index = old->index;
 352                 if (old != istate->split_index->base->cache[new->index - 1])
 353                         free(istate->split_index->base->cache[new->index - 1]);
 354                 istate->split_index->base->cache[new->index - 1] = new;
 355         }
 356 }
 357
 358 void add_split_index(struct index_state *istate)
 359 {
 360         if (!istate->split_index) {
 361                 init_split_index(istate);
 362                 istate->cache_changed |= SPLIT_INDEX_ORDERED;
 363         }
 364 }
 365
 366 void remove_split_index(struct index_state *istate)
 367 {
 368         if (!istate->split_index)
 369                 return;
 370         discard_split_index(istate);
 371         istate->cache_changed |= SOMETHING_CHANGED;
 372 }