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