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 static int write_strbuf(void *user_data, const void *data, size_t len)
  45 {
  46         struct strbuf *sb = user_data;
  47         strbuf_add(sb, data, len);
  48         return len;
  49 }
  50
  51 int write_link_extension(struct strbuf *sb,
  52                          struct index_state *istate)
  53 {
  54         struct split_index *si = istate->split_index;
  55         strbuf_add(sb, si->base_sha1, 20);
  56         if (!si->delete_bitmap && !si->replace_bitmap)
  57                 return 0;
  58         ewah_serialize_to(si->delete_bitmap, write_strbuf, sb);
  59         ewah_serialize_to(si->replace_bitmap, write_strbuf, sb);
  60         return 0;
  61 }
  62
  63 static void mark_base_index_entries(struct index_state *base)
  64 {
  65         int i;
  66         /*
  67          * To keep track of the shared entries between
  68          * istate->base->cache[] and istate->cache[], base entry
  69          * position is stored in each base entry. All positions start
  70          * from 1 instead of 0, which is resrved to say "this is a new
  71          * entry".
  72          */
  73         for (i = 0; i < base->cache_nr; i++)
  74                 base->cache[i]->index = i + 1;
  75 }
  76
  77 void move_cache_to_base_index(struct index_state *istate)
  78 {
  79         struct split_index *si = istate->split_index;
  80         int i;
  81
  82         /*
  83          * do not delete old si->base, its index entries may be shared
  84          * with istate->cache[]. Accept a bit of leaking here because
  85          * this code is only used by short-lived update-index.
  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         memcpy(si->base->cache, istate->cache,
  94                sizeof(*istate->cache) * istate->cache_nr);
  95         mark_base_index_entries(si->base);
  96         for (i = 0; i < si->base->cache_nr; i++)
  97                 si->base->cache[i]->ce_flags &= ~CE_UPDATE_IN_BASE;
  98 }
  99
 100 static void mark_entry_for_delete(size_t pos, void *data)
 101 {
 102         struct index_state *istate = data;
 103         if (pos >= istate->cache_nr)
 104                 die("position for delete %d exceeds base index size %d",
 105                     (int)pos, istate->cache_nr);
 106         istate->cache[pos]->ce_flags |= CE_REMOVE;
 107         istate->split_index->nr_deletions = 1;
 108 }
 109
 110 static void replace_entry(size_t pos, void *data)
 111 {
 112         struct index_state *istate = data;
 113         struct split_index *si = istate->split_index;
 114         struct cache_entry *dst, *src;
 115
 116         if (pos >= istate->cache_nr)
 117                 die("position for replacement %d exceeds base index size %d",
 118                     (int)pos, istate->cache_nr);
 119         if (si->nr_replacements >= si->saved_cache_nr)
 120                 die("too many replacements (%d vs %d)",
 121                     si->nr_replacements, si->saved_cache_nr);
 122         dst = istate->cache[pos];
 123         if (dst->ce_flags & CE_REMOVE)
 124                 die("entry %d is marked as both replaced and deleted",
 125                     (int)pos);
 126         src = si->saved_cache[si->nr_replacements];
 127         if (ce_namelen(src))
 128                 die("corrupt link extension, entry %d should have "
 129                     "zero length name", (int)pos);
 130         src->index = pos + 1;
 131         src->ce_flags |= CE_UPDATE_IN_BASE;
 132         src->ce_namelen = dst->ce_namelen;
 133         copy_cache_entry(dst, src);
 134         free(src);
 135         si->nr_replacements++;
 136 }
 137
 138 void merge_base_index(struct index_state *istate)
 139 {
 140         struct split_index *si = istate->split_index;
 141         unsigned int i;
 142
 143         mark_base_index_entries(si->base);
 144
 145         si->saved_cache     = istate->cache;
 146         si->saved_cache_nr  = istate->cache_nr;
 147         istate->cache_nr    = si->base->cache_nr;
 148         istate->cache       = NULL;
 149         istate->cache_alloc = 0;
 150         ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);
 151         memcpy(istate->cache, si->base->cache,
 152                sizeof(*istate->cache) * istate->cache_nr);
 153
 154         si->nr_deletions = 0;
 155         si->nr_replacements = 0;
 156         ewah_each_bit(si->replace_bitmap, replace_entry, istate);
 157         ewah_each_bit(si->delete_bitmap, mark_entry_for_delete, istate);
 158         if (si->nr_deletions)
 159                 remove_marked_cache_entries(istate);
 160
 161         for (i = si->nr_replacements; i < si->saved_cache_nr; i++) {
 162                 if (!ce_namelen(si->saved_cache[i]))
 163                         die("corrupt link extension, entry %d should "
 164                             "have non-zero length name", i);
 165                 add_index_entry(istate, si->saved_cache[i],
 166                                 ADD_CACHE_OK_TO_ADD |
 167                                 ADD_CACHE_KEEP_CACHE_TREE |
 168                                 /*
 169                                  * we may have to replay what
 170                                  * merge-recursive.c:update_stages()
 171                                  * does, which has this flag on
 172                                  */
 173                                 ADD_CACHE_SKIP_DFCHECK);
 174                 si->saved_cache[i] = NULL;
 175         }
 176
 177         ewah_free(si->delete_bitmap);
 178         ewah_free(si->replace_bitmap);
 179         free(si->saved_cache);
 180         si->delete_bitmap  = NULL;
 181         si->replace_bitmap = NULL;
 182         si->saved_cache    = NULL;
 183         si->saved_cache_nr = 0;
 184 }
 185
 186 void prepare_to_write_split_index(struct index_state *istate)
 187 {
 188         struct split_index *si = init_split_index(istate);
 189         struct cache_entry **entries = NULL, *ce;
 190         int i, nr_entries = 0, nr_alloc = 0;
 191
 192         si->delete_bitmap = ewah_new();
 193         si->replace_bitmap = ewah_new();
 194
 195         if (si->base) {
 196                 /* Go through istate->cache[] and mark CE_MATCHED to
 197                  * entry with positive index. We'll go through
 198                  * base->cache[] later to delete all entries in base
 199                  * that are not marked eith either CE_MATCHED or
 200                  * CE_UPDATE_IN_BASE. If istate->cache[i] is a
 201                  * duplicate, deduplicate it.
 202                  */
 203                 for (i = 0; i < istate->cache_nr; i++) {
 204                         struct cache_entry *base;
 205                         /* namelen is checked separately */
 206                         const unsigned int ondisk_flags =
 207                                 CE_STAGEMASK | CE_VALID | CE_EXTENDED_FLAGS;
 208                         unsigned int ce_flags, base_flags, ret;
 209                         ce = istate->cache[i];
 210                         if (!ce->index)
 211                                 continue;
 212                         if (ce->index > si->base->cache_nr) {
 213                                 ce->index = 0;
 214                                 continue;
 215                         }
 216                         ce->ce_flags |= CE_MATCHED; /* or "shared" */
 217                         base = si->base->cache[ce->index - 1];
 218                         if (ce == base)
 219                                 continue;
 220                         if (ce->ce_namelen != base->ce_namelen ||
 221                             strcmp(ce->name, base->name)) {
 222                                 ce->index = 0;
 223                                 continue;
 224                         }
 225                         ce_flags = ce->ce_flags;
 226                         base_flags = base->ce_flags;
 227                         /* only on-disk flags matter */
 228                         ce->ce_flags   &= ondisk_flags;
 229                         base->ce_flags &= ondisk_flags;
 230                         ret = memcmp(&ce->ce_stat_data, &base->ce_stat_data,
 231                                      offsetof(struct cache_entry, name) -
 232                                      offsetof(struct cache_entry, ce_stat_data));
 233                         ce->ce_flags = ce_flags;
 234                         base->ce_flags = base_flags;
 235                         if (ret)
 236                                 ce->ce_flags |= CE_UPDATE_IN_BASE;
 237                         free(base);
 238                         si->base->cache[ce->index - 1] = ce;
 239                 }
 240                 for (i = 0; i < si->base->cache_nr; i++) {
 241                         ce = si->base->cache[i];
 242                         if ((ce->ce_flags & CE_REMOVE) ||
 243                             !(ce->ce_flags & CE_MATCHED))
 244                                 ewah_set(si->delete_bitmap, i);
 245                         else if (ce->ce_flags & CE_UPDATE_IN_BASE) {
 246                                 ewah_set(si->replace_bitmap, i);
 247                                 ce->ce_flags |= CE_STRIP_NAME;
 248                                 ALLOC_GROW(entries, nr_entries+1, nr_alloc);
 249                                 entries[nr_entries++] = ce;
 250                         }
 251                 }
 252         }
 253
 254         for (i = 0; i < istate->cache_nr; i++) {
 255                 ce = istate->cache[i];
 256                 if ((!si->base || !ce->index) && !(ce->ce_flags & CE_REMOVE)) {
 257                         assert(!(ce->ce_flags & CE_STRIP_NAME));
 258                         ALLOC_GROW(entries, nr_entries+1, nr_alloc);
 259                         entries[nr_entries++] = ce;
 260                 }
 261                 ce->ce_flags &= ~CE_MATCHED;
 262         }
 263
 264         /*
 265          * take cache[] out temporarily, put entries[] in its place
 266          * for writing
 267          */
 268         si->saved_cache = istate->cache;
 269         si->saved_cache_nr = istate->cache_nr;
 270         istate->cache = entries;
 271         istate->cache_nr = nr_entries;
 272 }
 273
 274 void finish_writing_split_index(struct index_state *istate)
 275 {
 276         struct split_index *si = init_split_index(istate);
 277
 278         ewah_free(si->delete_bitmap);
 279         ewah_free(si->replace_bitmap);
 280         si->delete_bitmap = NULL;
 281         si->replace_bitmap = NULL;
 282         free(istate->cache);
 283         istate->cache = si->saved_cache;
 284         istate->cache_nr = si->saved_cache_nr;
 285 }
 286
 287 void discard_split_index(struct index_state *istate)
 288 {
 289         struct split_index *si = istate->split_index;
 290         if (!si)
 291                 return;
 292         istate->split_index = NULL;
 293         si->refcount--;
 294         if (si->refcount)
 295                 return;
 296         if (si->base) {
 297                 discard_index(si->base);
 298                 free(si->base);
 299         }
 300         free(si);
 301 }
 302
 303 void save_or_free_index_entry(struct index_state *istate, struct cache_entry *ce)
 304 {
 305         if (ce->index &&
 306             istate->split_index &&
 307             istate->split_index->base &&
 308             ce->index <= istate->split_index->base->cache_nr &&
 309             ce == istate->split_index->base->cache[ce->index - 1])
 310                 ce->ce_flags |= CE_REMOVE;
 311         else
 312                 free(ce);
 313 }
 314
 315 void replace_index_entry_in_base(struct index_state *istate,
 316                                  struct cache_entry *old,
 317                                  struct cache_entry *new)
 318 {
 319         if (old->index &&
 320             istate->split_index &&
 321             istate->split_index->base &&
 322             old->index <= istate->split_index->base->cache_nr) {
 323                 new->index = old->index;
 324                 if (old != istate->split_index->base->cache[new->index - 1])
 325                         free(istate->split_index->base->cache[new->index - 1]);
 326                 istate->split_index->base->cache[new->index - 1] = new;
 327         }
 328 }