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          * do not delete old si->base, its index entries may be shared
  77          * with istate->cache[]. Accept a bit of leaking here because
  78          * this code is only used by short-lived update-index.
  79          */
  80         si->base = xcalloc(1, sizeof(*si->base));
  81         si->base->version = istate->version;
  82         /* zero timestamp disables racy test in ce_write_index() */
  83         si->base->timestamp = istate->timestamp;
  84         ALLOC_GROW(si->base->cache, istate->cache_nr, si->base->cache_alloc);
  85         si->base->cache_nr = istate->cache_nr;
  86         COPY_ARRAY(si->base->cache, istate->cache, istate->cache_nr);
  87         mark_base_index_entries(si->base);
  88         for (i = 0; i < si->base->cache_nr; i++)
  89                 si->base->cache[i]->ce_flags &= ~CE_UPDATE_IN_BASE;
  90 }
  91
  92 static void mark_entry_for_delete(size_t pos, void *data)
  93 {
  94         struct index_state *istate = data;
  95         if (pos >= istate->cache_nr)
  96                 die("position for delete %d exceeds base index size %d",
  97                     (int)pos, istate->cache_nr);
  98         istate->cache[pos]->ce_flags |= CE_REMOVE;
  99         istate->split_index->nr_deletions = 1;
 100 }
 101
 102 static void replace_entry(size_t pos, void *data)
 103 {
 104         struct index_state *istate = data;
 105         struct split_index *si = istate->split_index;
 106         struct cache_entry *dst, *src;
 107
 108         if (pos >= istate->cache_nr)
 109                 die("position for replacement %d exceeds base index size %d",
 110                     (int)pos, istate->cache_nr);
 111         if (si->nr_replacements >= si->saved_cache_nr)
 112                 die("too many replacements (%d vs %d)",
 113                     si->nr_replacements, si->saved_cache_nr);
 114         dst = istate->cache[pos];
 115         if (dst->ce_flags & CE_REMOVE)
 116                 die("entry %d is marked as both replaced and deleted",
 117                     (int)pos);
 118         src = si->saved_cache[si->nr_replacements];
 119         if (ce_namelen(src))
 120                 die("corrupt link extension, entry %d should have "
 121                     "zero length name", (int)pos);
 122         src->index = pos + 1;
 123         src->ce_flags |= CE_UPDATE_IN_BASE;
 124         src->ce_namelen = dst->ce_namelen;
 125         copy_cache_entry(dst, src);
 126         free(src);
 127         si->nr_replacements++;
 128 }
 129
 130 void merge_base_index(struct index_state *istate)
 131 {
 132         struct split_index *si = istate->split_index;
 133         unsigned int i;
 134
 135         mark_base_index_entries(si->base);
 136
 137         si->saved_cache     = istate->cache;
 138         si->saved_cache_nr  = istate->cache_nr;
 139         istate->cache_nr    = si->base->cache_nr;
 140         istate->cache       = NULL;
 141         istate->cache_alloc = 0;
 142         ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);
 143         COPY_ARRAY(istate->cache, si->base->cache, istate->cache_nr);
 144
 145         si->nr_deletions = 0;
 146         si->nr_replacements = 0;
 147         ewah_each_bit(si->replace_bitmap, replace_entry, istate);
 148         ewah_each_bit(si->delete_bitmap, mark_entry_for_delete, istate);
 149         if (si->nr_deletions)
 150                 remove_marked_cache_entries(istate);
 151
 152         for (i = si->nr_replacements; i < si->saved_cache_nr; i++) {
 153                 if (!ce_namelen(si->saved_cache[i]))
 154                         die("corrupt link extension, entry %d should "
 155                             "have non-zero length name", i);
 156                 add_index_entry(istate, si->saved_cache[i],
 157                                 ADD_CACHE_OK_TO_ADD |
 158                                 ADD_CACHE_KEEP_CACHE_TREE |
 159                                 /*
 160                                  * we may have to replay what
 161                                  * merge-recursive.c:update_stages()
 162                                  * does, which has this flag on
 163                                  */
 164                                 ADD_CACHE_SKIP_DFCHECK);
 165                 si->saved_cache[i] = NULL;
 166         }
 167
 168         ewah_free(si->delete_bitmap);
 169         ewah_free(si->replace_bitmap);
 170         FREE_AND_NULL(si->saved_cache);
 171         si->delete_bitmap  = NULL;
 172         si->replace_bitmap = NULL;
 173         si->saved_cache_nr = 0;
 174 }
 175
 176 void prepare_to_write_split_index(struct index_state *istate)
 177 {
 178         struct split_index *si = init_split_index(istate);
 179         struct cache_entry **entries = NULL, *ce;
 180         int i, nr_entries = 0, nr_alloc = 0;
 181
 182         si->delete_bitmap = ewah_new();
 183         si->replace_bitmap = ewah_new();
 184
 185         if (si->base) {
 186                 /* Go through istate->cache[] and mark CE_MATCHED to
 187                  * entry with positive index. We'll go through
 188                  * base->cache[] later to delete all entries in base
 189                  * that are not marked with either CE_MATCHED or
 190                  * CE_UPDATE_IN_BASE. If istate->cache[i] is a
 191                  * duplicate, deduplicate it.
 192                  */
 193                 for (i = 0; i < istate->cache_nr; i++) {
 194                         struct cache_entry *base;
 195                         /* namelen is checked separately */
 196                         const unsigned int ondisk_flags =
 197                                 CE_STAGEMASK | CE_VALID | CE_EXTENDED_FLAGS;
 198                         unsigned int ce_flags, base_flags, ret;
 199                         ce = istate->cache[i];
 200                         if (!ce->index)
 201                                 continue;
 202                         if (ce->index > si->base->cache_nr) {
 203                                 ce->index = 0;
 204                                 continue;
 205                         }
 206                         ce->ce_flags |= CE_MATCHED; /* or "shared" */
 207                         base = si->base->cache[ce->index - 1];
 208                         if (ce == base)
 209                                 continue;
 210                         if (ce->ce_namelen != base->ce_namelen ||
 211                             strcmp(ce->name, base->name)) {
 212                                 ce->index = 0;
 213                                 continue;
 214                         }
 215                         ce_flags = ce->ce_flags;
 216                         base_flags = base->ce_flags;
 217                         /* only on-disk flags matter */
 218                         ce->ce_flags   &= ondisk_flags;
 219                         base->ce_flags &= ondisk_flags;
 220                         ret = memcmp(&ce->ce_stat_data, &base->ce_stat_data,
 221                                      offsetof(struct cache_entry, name) -
 222                                      offsetof(struct cache_entry, ce_stat_data));
 223                         ce->ce_flags = ce_flags;
 224                         base->ce_flags = base_flags;
 225                         if (ret)
 226                                 ce->ce_flags |= CE_UPDATE_IN_BASE;
 227                         free(base);
 228                         si->base->cache[ce->index - 1] = ce;
 229                 }
 230                 for (i = 0; i < si->base->cache_nr; i++) {
 231                         ce = si->base->cache[i];
 232                         if ((ce->ce_flags & CE_REMOVE) ||
 233                             !(ce->ce_flags & CE_MATCHED))
 234                                 ewah_set(si->delete_bitmap, i);
 235                         else if (ce->ce_flags & CE_UPDATE_IN_BASE) {
 236                                 ewah_set(si->replace_bitmap, i);
 237                                 ce->ce_flags |= CE_STRIP_NAME;
 238                                 ALLOC_GROW(entries, nr_entries+1, nr_alloc);
 239                                 entries[nr_entries++] = ce;
 240                         }
 241                 }
 242         }
 243
 244         for (i = 0; i < istate->cache_nr; i++) {
 245                 ce = istate->cache[i];
 246                 if ((!si->base || !ce->index) && !(ce->ce_flags & CE_REMOVE)) {
 247                         assert(!(ce->ce_flags & CE_STRIP_NAME));
 248                         ALLOC_GROW(entries, nr_entries+1, nr_alloc);
 249                         entries[nr_entries++] = ce;
 250                 }
 251                 ce->ce_flags &= ~CE_MATCHED;
 252         }
 253
 254         /*
 255          * take cache[] out temporarily, put entries[] in its place
 256          * for writing
 257          */
 258         si->saved_cache = istate->cache;
 259         si->saved_cache_nr = istate->cache_nr;
 260         istate->cache = entries;
 261         istate->cache_nr = nr_entries;
 262 }
 263
 264 void finish_writing_split_index(struct index_state *istate)
 265 {
 266         struct split_index *si = init_split_index(istate);
 267
 268         ewah_free(si->delete_bitmap);
 269         ewah_free(si->replace_bitmap);
 270         si->delete_bitmap = NULL;
 271         si->replace_bitmap = NULL;
 272         free(istate->cache);
 273         istate->cache = si->saved_cache;
 274         istate->cache_nr = si->saved_cache_nr;
 275 }
 276
 277 void discard_split_index(struct index_state *istate)
 278 {
 279         struct split_index *si = istate->split_index;
 280         if (!si)
 281                 return;
 282         istate->split_index = NULL;
 283         si->refcount--;
 284         if (si->refcount)
 285                 return;
 286         if (si->base) {
 287                 discard_index(si->base);
 288                 free(si->base);
 289         }
 290         free(si);
 291 }
 292
 293 void save_or_free_index_entry(struct index_state *istate, struct cache_entry *ce)
 294 {
 295         if (ce->index &&
 296             istate->split_index &&
 297             istate->split_index->base &&
 298             ce->index <= istate->split_index->base->cache_nr &&
 299             ce == istate->split_index->base->cache[ce->index - 1])
 300                 ce->ce_flags |= CE_REMOVE;
 301         else
 302                 free(ce);
 303 }
 304
 305 void replace_index_entry_in_base(struct index_state *istate,
 306                                  struct cache_entry *old,
 307                                  struct cache_entry *new)
 308 {
 309         if (old->index &&
 310             istate->split_index &&
 311             istate->split_index->base &&
 312             old->index <= istate->split_index->base->cache_nr) {
 313                 new->index = old->index;
 314                 if (old != istate->split_index->base->cache[new->index - 1])
 315                         free(istate->split_index->base->cache[new->index - 1]);
 316                 istate->split_index->base->cache[new->index - 1] = new;
 317         }
 318 }
 319
 320 void add_split_index(struct index_state *istate)
 321 {
 322         if (!istate->split_index) {
 323                 init_split_index(istate);
 324                 istate->cache_changed |= SPLIT_INDEX_ORDERED;
 325         }
 326 }
 327
 328 void remove_split_index(struct index_state *istate)
 329 {
 330         if (istate->split_index) {
 331                 /*
 332                  * can't discard_split_index(&the_index); because that
 333                  * will destroy split_index->base->cache[], which may
 334                  * be shared with the_index.cache[]. So yeah we're
 335                  * leaking a bit here.
 336                  */
 337                 istate->split_index = NULL;
 338                 istate->cache_changed |= SOMETHING_CHANGED;
 339         }
 340 }