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