git/sparse-index.c
Victoria Dye b93fea08d2 sparse-index: add ensure_correct_sparsity function
The `ensure_correct_sparsity` function is intended to provide a means of
aligning the in-core index with the sparsity required by the repository
settings and other properties of the index. The function first checks
whether a sparse index is allowed (per repository & sparse checkout pattern
settings). If the sparse index may be used, the index is converted to
sparse; otherwise, it is explicitly expanded with `ensure_full_index`.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-11-24 16:32:38 -08:00

416 lines
10 KiB
C

#include "cache.h"
#include "repository.h"
#include "sparse-index.h"
#include "tree.h"
#include "pathspec.h"
#include "trace2.h"
#include "cache-tree.h"
#include "config.h"
#include "dir.h"
#include "fsmonitor.h"
static struct cache_entry *construct_sparse_dir_entry(
struct index_state *istate,
const char *sparse_dir,
struct cache_tree *tree)
{
struct cache_entry *de;
de = make_cache_entry(istate, S_IFDIR, &tree->oid, sparse_dir, 0, 0);
de->ce_flags |= CE_SKIP_WORKTREE;
return de;
}
/*
* Returns the number of entries "inserted" into the index.
*/
static int convert_to_sparse_rec(struct index_state *istate,
int num_converted,
int start, int end,
const char *ct_path, size_t ct_pathlen,
struct cache_tree *ct)
{
int i, can_convert = 1;
int start_converted = num_converted;
struct strbuf child_path = STRBUF_INIT;
/*
* Is the current path outside of the sparse cone?
* Then check if the region can be replaced by a sparse
* directory entry (everything is sparse and merged).
*/
if (path_in_sparse_checkout(ct_path, istate))
can_convert = 0;
for (i = start; can_convert && i < end; i++) {
struct cache_entry *ce = istate->cache[i];
if (ce_stage(ce) ||
S_ISGITLINK(ce->ce_mode) ||
!(ce->ce_flags & CE_SKIP_WORKTREE))
can_convert = 0;
}
if (can_convert) {
struct cache_entry *se;
se = construct_sparse_dir_entry(istate, ct_path, ct);
istate->cache[num_converted++] = se;
return 1;
}
for (i = start; i < end; ) {
int count, span, pos = -1;
const char *base, *slash;
struct cache_entry *ce = istate->cache[i];
/*
* Detect if this is a normal entry outside of any subtree
* entry.
*/
base = ce->name + ct_pathlen;
slash = strchr(base, '/');
if (slash)
pos = cache_tree_subtree_pos(ct, base, slash - base);
if (pos < 0) {
istate->cache[num_converted++] = ce;
i++;
continue;
}
strbuf_setlen(&child_path, 0);
strbuf_add(&child_path, ce->name, slash - ce->name + 1);
span = ct->down[pos]->cache_tree->entry_count;
count = convert_to_sparse_rec(istate,
num_converted, i, i + span,
child_path.buf, child_path.len,
ct->down[pos]->cache_tree);
num_converted += count;
i += span;
}
strbuf_release(&child_path);
return num_converted - start_converted;
}
int set_sparse_index_config(struct repository *repo, int enable)
{
int res;
char *config_path = repo_git_path(repo, "config.worktree");
res = git_config_set_in_file_gently(config_path,
"index.sparse",
enable ? "true" : NULL);
free(config_path);
prepare_repo_settings(repo);
repo->settings.sparse_index = enable;
return res;
}
static int index_has_unmerged_entries(struct index_state *istate)
{
int i;
for (i = 0; i < istate->cache_nr; i++) {
if (ce_stage(istate->cache[i]))
return 1;
}
return 0;
}
static int is_sparse_index_allowed(struct index_state *istate, int flags)
{
if (!core_apply_sparse_checkout || !core_sparse_checkout_cone)
return 0;
if (!istate->repo)
istate->repo = the_repository;
if (!(flags & SPARSE_INDEX_MEMORY_ONLY)) {
int test_env;
/*
* The sparse index is not (yet) integrated with a split index.
*/
if (istate->split_index)
return 0;
/*
* The GIT_TEST_SPARSE_INDEX environment variable triggers the
* index.sparse config variable to be on.
*/
test_env = git_env_bool("GIT_TEST_SPARSE_INDEX", -1);
if (test_env >= 0)
set_sparse_index_config(istate->repo, test_env);
/*
* Only convert to sparse if index.sparse is set.
*/
prepare_repo_settings(istate->repo);
if (!istate->repo->settings.sparse_index)
return 0;
}
if (init_sparse_checkout_patterns(istate))
return 0;
/*
* We need cone-mode patterns to use sparse-index. If a user edits
* their sparse-checkout file manually, then we can detect during
* parsing that they are not actually using cone-mode patterns and
* hence we need to abort this conversion _without error_. Warnings
* already exist in the pattern parsing to inform the user of their
* bad patterns.
*/
if (!istate->sparse_checkout_patterns->use_cone_patterns)
return 0;
return 1;
}
int convert_to_sparse(struct index_state *istate, int flags)
{
/*
* If the index is already sparse, empty, or otherwise
* cannot be converted to sparse, do not convert.
*/
if (istate->sparse_index || !istate->cache_nr ||
!is_sparse_index_allowed(istate, flags))
return 0;
/*
* NEEDSWORK: If we have unmerged entries, then stay full.
* Unmerged entries prevent the cache-tree extension from working.
*/
if (index_has_unmerged_entries(istate))
return 0;
if (!cache_tree_fully_valid(istate->cache_tree)) {
/* Clear and recompute the cache-tree */
cache_tree_free(&istate->cache_tree);
/*
* Silently return if there is a problem with the cache tree update,
* which might just be due to a conflict state in some entry.
*
* This might create new tree objects, so be sure to use
* WRITE_TREE_MISSING_OK.
*/
if (cache_tree_update(istate, WRITE_TREE_MISSING_OK))
return 0;
}
remove_fsmonitor(istate);
trace2_region_enter("index", "convert_to_sparse", istate->repo);
istate->cache_nr = convert_to_sparse_rec(istate,
0, 0, istate->cache_nr,
"", 0, istate->cache_tree);
/* Clear and recompute the cache-tree */
cache_tree_free(&istate->cache_tree);
cache_tree_update(istate, 0);
istate->fsmonitor_has_run_once = 0;
FREE_AND_NULL(istate->fsmonitor_dirty);
FREE_AND_NULL(istate->fsmonitor_last_update);
istate->sparse_index = 1;
trace2_region_leave("index", "convert_to_sparse", istate->repo);
return 0;
}
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 | CE_EXTENDED;
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));
memcpy(&istate->dir_hash, &full->dir_hash, sizeof(full->dir_hash));
istate->sparse_index = 0;
free(istate->cache);
istate->cache = full->cache;
istate->cache_nr = full->cache_nr;
istate->cache_alloc = full->cache_alloc;
istate->fsmonitor_has_run_once = 0;
FREE_AND_NULL(istate->fsmonitor_dirty);
FREE_AND_NULL(istate->fsmonitor_last_update);
strbuf_release(&base);
free(full);
/* Clear and recompute the cache-tree */
cache_tree_free(&istate->cache_tree);
cache_tree_update(istate, 0);
trace2_region_leave("index", "ensure_full_index", istate->repo);
}
void ensure_correct_sparsity(struct index_state *istate)
{
/*
* If the index can be sparse, make it sparse. Otherwise,
* ensure the index is full.
*/
if (is_sparse_index_allowed(istate, 0))
convert_to_sparse(istate, 0);
else
ensure_full_index(istate);
}
/*
* This static global helps avoid infinite recursion between
* expand_to_path() and index_file_exists().
*/
static int in_expand_to_path = 0;
void expand_to_path(struct index_state *istate,
const char *path, size_t pathlen, int icase)
{
struct strbuf path_mutable = STRBUF_INIT;
size_t substr_len;
/* prevent extra recursion */
if (in_expand_to_path)
return;
if (!istate || !istate->sparse_index)
return;
if (!istate->repo)
istate->repo = the_repository;
in_expand_to_path = 1;
/*
* We only need to actually expand a region if the
* following are both true:
*
* 1. 'path' is not already in the index.
* 2. Some parent directory of 'path' is a sparse directory.
*/
if (index_file_exists(istate, path, pathlen, icase))
goto cleanup;
strbuf_add(&path_mutable, path, pathlen);
strbuf_addch(&path_mutable, '/');
/* Check the name hash for all parent directories */
substr_len = 0;
while (substr_len < pathlen) {
char temp;
char *replace = strchr(path_mutable.buf + substr_len, '/');
if (!replace)
break;
/* replace the character _after_ the slash */
replace++;
temp = *replace;
*replace = '\0';
if (index_file_exists(istate, path_mutable.buf,
path_mutable.len, icase)) {
/*
* We found a parent directory in the name-hash
* hashtable, because only sparse directory entries
* have a trailing '/' character. Since "path" wasn't
* in the index, perhaps it exists within this
* sparse-directory. Expand accordingly.
*/
ensure_full_index(istate);
break;
}
*replace = temp;
substr_len = replace - path_mutable.buf;
}
cleanup:
strbuf_release(&path_mutable);
in_expand_to_path = 0;
}