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split-index: the reading part
CE_REMOVE'd entries are removed here because only parts of the code
base (unpack_trees in fact) test this bit when they look for the
presence of an entry. Leaving them may confuse the code ignores this
bit and expects to see a real entry.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Nguyễn Thái Ngọc Duy authored and Junio C Hamano committed Jun 13, 2014
1 parent 96a1d8d commit 76b07b3
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Showing 3 changed files with 84 additions and 4 deletions.
2 changes: 0 additions & 2 deletions read-cache.c
Expand Up @@ -1569,8 +1569,6 @@ int read_index_from(struct index_state *istate, const char *path)

if (is_null_sha1(split_index->base_sha1))
return ret;
if (istate->cache_nr)
die("index in split-index mode must contain no entries");

if (split_index->base)
discard_index(split_index->base);
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84 changes: 82 additions & 2 deletions split-index.c
Expand Up @@ -16,13 +16,27 @@ int read_link_extension(struct index_state *istate,
{
const unsigned char *data = data_;
struct split_index *si;
int ret;

if (sz < 20)
return error("corrupt link extension (too short)");
si = init_split_index(istate);
hashcpy(si->base_sha1, data);
data += 20;
sz -= 20;
if (sz)
if (!sz)
return 0;
si->delete_bitmap = ewah_new();
ret = ewah_read_mmap(si->delete_bitmap, data, sz);
if (ret < 0)
return error("corrupt delete bitmap in link extension");
data += ret;
sz -= ret;
si->replace_bitmap = ewah_new();
ret = ewah_read_mmap(si->replace_bitmap, data, sz);
if (ret < 0)
return error("corrupt replace bitmap in link extension");
if (ret != sz)
return error("garbage at the end of link extension");
return 0;
}
Expand Down Expand Up @@ -60,15 +74,81 @@ static void mark_base_index_entries(struct index_state *base)
base->cache[i]->index = i + 1;
}

static void mark_entry_for_delete(size_t pos, void *data)
{
struct index_state *istate = data;
if (pos >= istate->cache_nr)
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;
}

static void replace_entry(size_t pos, void *data)
{
struct index_state *istate = data;
struct split_index *si = istate->split_index;
struct cache_entry *dst, *src;
if (pos >= istate->cache_nr)
die("position for replacement %d exceeds base index size %d",
(int)pos, istate->cache_nr);
if (si->nr_replacements >= si->saved_cache_nr)
die("too many replacements (%d vs %d)",
si->nr_replacements, si->saved_cache_nr);
dst = istate->cache[pos];
if (dst->ce_flags & CE_REMOVE)
die("entry %d is marked as both replaced and deleted",
(int)pos);
src = si->saved_cache[si->nr_replacements];
src->index = pos + 1;
src->ce_flags |= CE_UPDATE_IN_BASE;
free(dst);
dst = src;
si->nr_replacements++;
}

void merge_base_index(struct index_state *istate)
{
struct split_index *si = istate->split_index;
unsigned int i;

mark_base_index_entries(si->base);
istate->cache_nr = si->base->cache_nr;

si->saved_cache = istate->cache;
si->saved_cache_nr = istate->cache_nr;
istate->cache_nr = si->base->cache_nr;
istate->cache = NULL;
istate->cache_alloc = 0;
ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);
memcpy(istate->cache, si->base->cache,
sizeof(*istate->cache) * istate->cache_nr);

si->nr_deletions = 0;
si->nr_replacements = 0;
ewah_each_bit(si->replace_bitmap, replace_entry, istate);
ewah_each_bit(si->delete_bitmap, mark_entry_for_delete, istate);
if (si->nr_deletions)
remove_marked_cache_entries(istate);

for (i = si->nr_replacements; i < si->saved_cache_nr; i++) {
add_index_entry(istate, si->saved_cache[i],
ADD_CACHE_OK_TO_ADD |
/*
* we may have to replay what
* merge-recursive.c:update_stages()
* does, which has this flag on
*/
ADD_CACHE_SKIP_DFCHECK);
si->saved_cache[i] = NULL;
}

ewah_free(si->delete_bitmap);
ewah_free(si->replace_bitmap);
free(si->saved_cache);
si->delete_bitmap = NULL;
si->replace_bitmap = NULL;
si->saved_cache = NULL;
si->saved_cache_nr = 0;
}

void prepare_to_write_split_index(struct index_state *istate)
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2 changes: 2 additions & 0 deletions split-index.h
Expand Up @@ -12,6 +12,8 @@ struct split_index {
struct ewah_bitmap *replace_bitmap;
struct cache_entry **saved_cache;
unsigned int saved_cache_nr;
unsigned int nr_deletions;
unsigned int nr_replacements;
int refcount;
};

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