git/sparse-index.c
Derrick Stolee 4300f8442a sparse-index: implement ensure_full_index()
We will mark an in-memory index_state as having sparse directory entries
with the sparse_index bit. These currently cannot exist, but we will add
a mechanism for collapsing a full index to a sparse one in a later
change. That will happen at write time, so we must first allow parsing
the format before writing it.

Commands or methods that require a full index in order to operate can
call ensure_full_index() to expand that index in-memory. This requires
parsing trees using that index's repository.

Sparse directory entries have a specific 'ce_mode' value. The macro
S_ISSPARSEDIR(ce->ce_mode) can check if a cache_entry 'ce' has this type.
This ce_mode is not possible with the existing index formats, so we don't
also verify all properties of a sparse-directory entry, which are:

 1. ce->ce_mode == 0040000
 2. ce->flags & CE_SKIP_WORKTREE is true
 3. ce->name[ce->namelen - 1] == '/' (ends in dir separator)
 4. ce->oid references a tree object.

These are all semi-enforced in ensure_full_index() to some extent. Any
deviation will cause a warning at minimum or a failure in the worst
case.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:45 -07:00

105 lines
2.6 KiB
C

#include "cache.h"
#include "repository.h"
#include "sparse-index.h"
#include "tree.h"
#include "pathspec.h"
#include "trace2.h"
static void set_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
{
ALLOC_GROW(istate->cache, nr + 1, istate->cache_alloc);
istate->cache[nr] = ce;
add_name_hash(istate, ce);
}
static int add_path_to_index(const struct object_id *oid,
struct strbuf *base, const char *path,
unsigned int mode, void *context)
{
struct index_state *istate = (struct index_state *)context;
struct cache_entry *ce;
size_t len = base->len;
if (S_ISDIR(mode))
return READ_TREE_RECURSIVE;
strbuf_addstr(base, path);
ce = make_cache_entry(istate, mode, oid, base->buf, 0, 0);
ce->ce_flags |= CE_SKIP_WORKTREE;
set_index_entry(istate, istate->cache_nr++, ce);
strbuf_setlen(base, len);
return 0;
}
void ensure_full_index(struct index_state *istate)
{
int i;
struct index_state *full;
struct strbuf base = STRBUF_INIT;
if (!istate || !istate->sparse_index)
return;
if (!istate->repo)
istate->repo = the_repository;
trace2_region_enter("index", "ensure_full_index", istate->repo);
/* initialize basics of new index */
full = xcalloc(1, sizeof(struct index_state));
memcpy(full, istate, sizeof(struct index_state));
/* then change the necessary things */
full->sparse_index = 0;
full->cache_alloc = (3 * istate->cache_alloc) / 2;
full->cache_nr = 0;
ALLOC_ARRAY(full->cache, full->cache_alloc);
for (i = 0; i < istate->cache_nr; i++) {
struct cache_entry *ce = istate->cache[i];
struct tree *tree;
struct pathspec ps;
if (!S_ISSPARSEDIR(ce->ce_mode)) {
set_index_entry(full, full->cache_nr++, ce);
continue;
}
if (!(ce->ce_flags & CE_SKIP_WORKTREE))
warning(_("index entry is a directory, but not sparse (%08x)"),
ce->ce_flags);
/* recursively walk into cd->name */
tree = lookup_tree(istate->repo, &ce->oid);
memset(&ps, 0, sizeof(ps));
ps.recursive = 1;
ps.has_wildcard = 1;
ps.max_depth = -1;
strbuf_setlen(&base, 0);
strbuf_add(&base, ce->name, strlen(ce->name));
read_tree_at(istate->repo, tree, &base, &ps,
add_path_to_index, full);
/* free directory entries. full entries are re-used */
discard_cache_entry(ce);
}
/* Copy back into original index. */
memcpy(&istate->name_hash, &full->name_hash, sizeof(full->name_hash));
istate->sparse_index = 0;
free(istate->cache);
istate->cache = full->cache;
istate->cache_nr = full->cache_nr;
istate->cache_alloc = full->cache_alloc;
strbuf_release(&base);
free(full);
trace2_region_leave("index", "ensure_full_index", istate->repo);
}