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