split-index: the writing part
[gitweb.git] / split-index.c
index b36c73b3aa95f41d1f3170deeda796bdc34996bc..57088071fce3503fdb983f3543c07b0b29e6000a 100644 (file)
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "split-index.h"
+#include "ewah/ewok.h"
 
 struct split_index *init_split_index(struct index_state *istate)
 {
@@ -26,11 +27,22 @@ int read_link_extension(struct index_state *istate,
        return 0;
 }
 
+static int write_strbuf(void *user_data, const void *data, size_t len)
+{
+       struct strbuf *sb = user_data;
+       strbuf_add(sb, data, len);
+       return len;
+}
+
 int write_link_extension(struct strbuf *sb,
                         struct index_state *istate)
 {
        struct split_index *si = istate->split_index;
        strbuf_add(sb, si->base_sha1, 20);
+       if (!si->delete_bitmap && !si->replace_bitmap)
+               return 0;
+       ewah_serialize_to(si->delete_bitmap, write_strbuf, sb);
+       ewah_serialize_to(si->replace_bitmap, write_strbuf, sb);
        return 0;
 }
 
@@ -62,14 +74,99 @@ void merge_base_index(struct index_state *istate)
 void prepare_to_write_split_index(struct index_state *istate)
 {
        struct split_index *si = init_split_index(istate);
-       /* take cache[] out temporarily */
+       struct cache_entry **entries = NULL, *ce;
+       int i, nr_entries = 0, nr_alloc = 0;
+
+       si->delete_bitmap = ewah_new();
+       si->replace_bitmap = ewah_new();
+
+       if (si->base) {
+               /* Go through istate->cache[] and mark CE_MATCHED to
+                * entry with positive index. We'll go through
+                * base->cache[] later to delete all entries in base
+                * that are not marked eith either CE_MATCHED or
+                * CE_UPDATE_IN_BASE. If istate->cache[i] is a
+                * duplicate, deduplicate it.
+                */
+               for (i = 0; i < istate->cache_nr; i++) {
+                       struct cache_entry *base;
+                       /* namelen is checked separately */
+                       const unsigned int ondisk_flags =
+                               CE_STAGEMASK | CE_VALID | CE_EXTENDED_FLAGS;
+                       unsigned int ce_flags, base_flags, ret;
+                       ce = istate->cache[i];
+                       if (!ce->index)
+                               continue;
+                       if (ce->index > si->base->cache_nr) {
+                               ce->index = 0;
+                               continue;
+                       }
+                       ce->ce_flags |= CE_MATCHED; /* or "shared" */
+                       base = si->base->cache[ce->index - 1];
+                       if (ce == base)
+                               continue;
+                       if (ce->ce_namelen != base->ce_namelen ||
+                           strcmp(ce->name, base->name)) {
+                               ce->index = 0;
+                               continue;
+                       }
+                       ce_flags = ce->ce_flags;
+                       base_flags = base->ce_flags;
+                       /* only on-disk flags matter */
+                       ce->ce_flags   &= ondisk_flags;
+                       base->ce_flags &= ondisk_flags;
+                       ret = memcmp(&ce->ce_stat_data, &base->ce_stat_data,
+                                    offsetof(struct cache_entry, name) -
+                                    offsetof(struct cache_entry, ce_stat_data));
+                       ce->ce_flags = ce_flags;
+                       base->ce_flags = base_flags;
+                       if (ret)
+                               ce->ce_flags |= CE_UPDATE_IN_BASE;
+                       free(base);
+                       si->base->cache[ce->index - 1] = ce;
+               }
+               for (i = 0; i < si->base->cache_nr; i++) {
+                       ce = si->base->cache[i];
+                       if ((ce->ce_flags & CE_REMOVE) ||
+                           !(ce->ce_flags & CE_MATCHED))
+                               ewah_set(si->delete_bitmap, i);
+                       else if (ce->ce_flags & CE_UPDATE_IN_BASE) {
+                               ewah_set(si->replace_bitmap, i);
+                               ALLOC_GROW(entries, nr_entries+1, nr_alloc);
+                               entries[nr_entries++] = ce;
+                       }
+               }
+       }
+
+       for (i = 0; i < istate->cache_nr; i++) {
+               ce = istate->cache[i];
+               if ((!si->base || !ce->index) && !(ce->ce_flags & CE_REMOVE)) {
+                       ALLOC_GROW(entries, nr_entries+1, nr_alloc);
+                       entries[nr_entries++] = ce;
+               }
+               ce->ce_flags &= ~CE_MATCHED;
+       }
+
+       /*
+        * take cache[] out temporarily, put entries[] in its place
+        * for writing
+        */
+       si->saved_cache = istate->cache;
        si->saved_cache_nr = istate->cache_nr;
-       istate->cache_nr = 0;
+       istate->cache = entries;
+       istate->cache_nr = nr_entries;
 }
 
 void finish_writing_split_index(struct index_state *istate)
 {
        struct split_index *si = init_split_index(istate);
+
+       ewah_free(si->delete_bitmap);
+       ewah_free(si->replace_bitmap);
+       si->delete_bitmap = NULL;
+       si->replace_bitmap = NULL;
+       free(istate->cache);
+       istate->cache = si->saved_cache;
        istate->cache_nr = si->saved_cache_nr;
 }