Merge branch 'js/pack-objects-mutex-init-fix' into maint
[gitweb.git] / split-index.c
index 84f067e10d2cec1d77ec1a51f0f38cc5a29dd89f..5820412dc5203032d1247575d79c6107a163295a 100644 (file)
@@ -111,7 +111,7 @@ static void mark_entry_for_delete(size_t pos, void *data)
                die("position for delete %d exceeds base index size %d",
                    (int)pos, istate->cache_nr);
        istate->cache[pos]->ce_flags |= CE_REMOVE;
-       istate->split_index->nr_deletions = 1;
+       istate->split_index->nr_deletions++;
 }
 
 static void replace_entry(size_t pos, void *data)
@@ -188,6 +188,30 @@ void merge_base_index(struct index_state *istate)
        si->saved_cache_nr = 0;
 }
 
+/*
+ * Compare most of the fields in two cache entries, i.e. all except the
+ * hashmap_entry and the name.
+ */
+static int compare_ce_content(struct cache_entry *a, struct cache_entry *b)
+{
+       const unsigned int ondisk_flags = CE_STAGEMASK | CE_VALID |
+                                         CE_EXTENDED_FLAGS;
+       unsigned int ce_flags = a->ce_flags;
+       unsigned int base_flags = b->ce_flags;
+       int ret;
+
+       /* only on-disk flags matter */
+       a->ce_flags &= ondisk_flags;
+       b->ce_flags &= ondisk_flags;
+       ret = memcmp(&a->ce_stat_data, &b->ce_stat_data,
+                    offsetof(struct cache_entry, name) -
+                    offsetof(struct cache_entry, ce_stat_data));
+       a->ce_flags = ce_flags;
+       b->ce_flags = base_flags;
+
+       return ret;
+}
+
 void prepare_to_write_split_index(struct index_state *istate)
 {
        struct split_index *si = init_split_index(istate);
@@ -207,38 +231,109 @@ void prepare_to_write_split_index(struct index_state *istate)
                 */
                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)
+                       if (!ce->index) {
+                               /*
+                                * During simple update index operations this
+                                * is a cache entry that is not present in
+                                * the shared index.  It will be added to the
+                                * split index.
+                                *
+                                * However, it might also represent a file
+                                * that already has a cache entry in the
+                                * shared index, but a new index has just
+                                * been constructed by unpack_trees(), and
+                                * this entry now refers to different content
+                                * than what was recorded in the original
+                                * index, e.g. during 'read-tree -m HEAD^' or
+                                * 'checkout HEAD^'.  In this case the
+                                * original entry in the shared index will be
+                                * marked as deleted, and this entry will be
+                                * added to the split index.
+                                */
                                continue;
+                       }
                        if (ce->index > si->base->cache_nr) {
-                               ce->index = 0;
-                               continue;
+                               BUG("ce refers to a shared ce at %d, which is beyond the shared index size %d",
+                                   ce->index, si->base->cache_nr);
                        }
                        ce->ce_flags |= CE_MATCHED; /* or "shared" */
                        base = si->base->cache[ce->index - 1];
-                       if (ce == base)
+                       if (ce == base) {
+                               /* The entry is present in the shared index. */
+                               if (ce->ce_flags & CE_UPDATE_IN_BASE) {
+                                       /*
+                                        * Already marked for inclusion in
+                                        * the split index, either because
+                                        * the corresponding file was
+                                        * modified and the cached stat data
+                                        * was refreshed, or because there
+                                        * is already a replacement entry in
+                                        * the split index.
+                                        * Nothing more to do here.
+                                        */
+                               } else if (!ce_uptodate(ce) &&
+                                          is_racy_timestamp(istate, ce)) {
+                                       /*
+                                        * A racily clean cache entry stored
+                                        * only in the shared index: it must
+                                        * be added to the split index, so
+                                        * the subsequent do_write_index()
+                                        * can smudge its stat data.
+                                        */
+                                       ce->ce_flags |= CE_UPDATE_IN_BASE;
+                               } else {
+                                       /*
+                                        * The entry is only present in the
+                                        * shared index and it was not
+                                        * refreshed.
+                                        * Just leave it there.
+                                        */
+                               }
                                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)
+                       /*
+                        * This is the copy of a cache entry that is present
+                        * in the shared index, created by unpack_trees()
+                        * while it constructed a new index.
+                        */
+                       if (ce->ce_flags & CE_UPDATE_IN_BASE) {
+                               /*
+                                * Already marked for inclusion in the split
+                                * index, either because the corresponding
+                                * file was modified and the cached stat data
+                                * was refreshed, or because the original
+                                * entry already had a replacement entry in
+                                * the split index.
+                                * Nothing to do.
+                                */
+                       } else if (!ce_uptodate(ce) &&
+                                  is_racy_timestamp(istate, ce)) {
+                               /*
+                                * A copy of a racily clean cache entry from
+                                * the shared index.  It must be added to
+                                * the split index, so the subsequent
+                                * do_write_index() can smudge its stat data.
+                                */
                                ce->ce_flags |= CE_UPDATE_IN_BASE;
+                       } else {
+                               /*
+                                * Thoroughly compare the cached data to see
+                                * whether it should be marked for inclusion
+                                * in the split index.
+                                *
+                                * This comparison might be unnecessary, as
+                                * code paths modifying the cached data do
+                                * set CE_UPDATE_IN_BASE as well.
+                                */
+                               if (compare_ce_content(ce, base))
+                                       ce->ce_flags |= CE_UPDATE_IN_BASE;
+                       }
                        discard_cache_entry(base);
                        si->base->cache[ce->index - 1] = ce;
                }