git/sparse-index.c
Anh Le 8c7abdc596 index: raise a bug if the index is materialised more than once
If clear_skip_worktree_from_present_files() encounter a sparse directory,
it fully materialise the index which should expand any sparse directories
and start going through each entries again. If this happens more than once,
raise it with a BUG.

Signed-off-by: Anh Le <anh@canva.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2022-11-04 20:28:28 -04:00

605 lines
15 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"
struct modify_index_context {
struct index_state *write;
struct pattern_list *pl;
};
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 = repo_config_set_worktree_gently(repo,
"index.sparse",
enable ? "true" : "false");
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;
}
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 || git_env_bool("GIT_TEST_SPLIT_INDEX", 0))
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 == INDEX_COLLAPSED || !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 = INDEX_COLLAPSED;
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 modify_index_context *ctx = (struct modify_index_context *)context;
struct cache_entry *ce;
size_t len = base->len;
if (S_ISDIR(mode)) {
int dtype;
size_t baselen = base->len;
if (!ctx->pl)
return READ_TREE_RECURSIVE;
/*
* Have we expanded to a point outside of the sparse-checkout?
*
* Artificially pad the path name with a slash "/" to
* indicate it as a directory, and add an arbitrary file
* name ("-") so we can consider base->buf as a file name
* to match against the cone-mode patterns.
*
* If we compared just "path", then we would expand more
* than we should. Since every file at root is always
* included, we would expand every directory at root at
* least one level deep instead of using sparse directory
* entries.
*/
strbuf_addstr(base, path);
strbuf_add(base, "/-", 2);
if (path_matches_pattern_list(base->buf, base->len,
NULL, &dtype,
ctx->pl, ctx->write)) {
strbuf_setlen(base, baselen);
return READ_TREE_RECURSIVE;
}
/*
* The path "{base}{path}/" is a sparse directory. Create the correct
* name for inserting the entry into the index.
*/
strbuf_setlen(base, base->len - 1);
} else {
strbuf_addstr(base, path);
}
ce = make_cache_entry(ctx->write, mode, oid, base->buf, 0, 0);
ce->ce_flags |= CE_SKIP_WORKTREE | CE_EXTENDED;
set_index_entry(ctx->write, ctx->write->cache_nr++, ce);
strbuf_setlen(base, len);
return 0;
}
void expand_index(struct index_state *istate, struct pattern_list *pl)
{
int i;
struct index_state *full;
struct strbuf base = STRBUF_INIT;
const char *tr_region;
struct modify_index_context ctx;
/*
* If the index is already full, then keep it full. We will convert
* it to a sparse index on write, if possible.
*/
if (!istate || istate->sparse_index == INDEX_EXPANDED)
return;
/*
* If our index is sparse, but our new pattern set does not use
* cone mode patterns, then we need to expand the index before we
* continue. A NULL pattern set indicates a full expansion to a
* full index.
*/
if (pl && !pl->use_cone_patterns) {
pl = NULL;
} else {
/*
* We might contract file entries into sparse-directory
* entries, and for that we will need the cache tree to
* be recomputed.
*/
cache_tree_free(&istate->cache_tree);
/*
* If there is a problem creating the cache tree, then we
* need to expand to a full index since we cannot satisfy
* the current request as a sparse index.
*/
if (cache_tree_update(istate, 0))
pl = NULL;
}
if (!istate->repo)
istate->repo = the_repository;
/*
* A NULL pattern set indicates we are expanding a full index, so
* we use a special region name that indicates the full expansion.
* This is used by test cases, but also helps to differentiate the
* two cases.
*/
tr_region = pl ? "expand_index" : "ensure_full_index";
trace2_region_enter("index", tr_region, istate->repo);
/* initialize basics of new index */
full = xcalloc(1, sizeof(struct index_state));
memcpy(full, istate, sizeof(struct index_state));
/*
* This slightly-misnamed 'full' index might still be sparse if we
* are only modifying the list of sparse directories. This hinges
* on whether we have a non-NULL pattern list.
*/
full->sparse_index = pl ? INDEX_PARTIALLY_SPARSE : INDEX_EXPANDED;
/* then change the necessary things */
full->cache_alloc = (3 * istate->cache_alloc) / 2;
full->cache_nr = 0;
ALLOC_ARRAY(full->cache, full->cache_alloc);
ctx.write = full;
ctx.pl = pl;
for (i = 0; i < istate->cache_nr; i++) {
struct cache_entry *ce = istate->cache[i];
struct tree *tree;
struct pathspec ps;
int dtype;
if (!S_ISSPARSEDIR(ce->ce_mode)) {
set_index_entry(full, full->cache_nr++, ce);
continue;
}
/* We now have a sparse directory entry. Should we expand? */
if (pl &&
path_matches_pattern_list(ce->name, ce->ce_namelen,
NULL, &dtype,
pl, istate) == NOT_MATCHED) {
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, &ctx);
/* 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 = pl ? INDEX_PARTIALLY_SPARSE : INDEX_EXPANDED;
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", tr_region, istate->repo);
}
void ensure_full_index(struct index_state *istate)
{
expand_index(istate, NULL);
}
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);
}
static int path_found(const char *path, const char **dirname, size_t *dir_len,
int *dir_found)
{
struct stat st;
char *newdir;
char *tmp;
/*
* If dirname corresponds to a directory that doesn't exist, and this
* path starts with dirname, then path can't exist.
*/
if (!*dir_found && !memcmp(path, *dirname, *dir_len))
return 0;
/*
* If path itself exists, return 1.
*/
if (!lstat(path, &st))
return 1;
/*
* Otherwise, path does not exist so we'll return 0...but we'll first
* determine some info about its parent directory so we can avoid
* lstat calls for future cache entries.
*/
newdir = strrchr(path, '/');
if (!newdir)
return 0; /* Didn't find a parent dir; just return 0 now. */
/*
* If path starts with directory (which we already lstat'ed and found),
* then no need to lstat parent directory again.
*/
if (*dir_found && *dirname && memcmp(path, *dirname, *dir_len))
return 0;
/* Free previous dirname, and cache path's dirname */
*dirname = path;
*dir_len = newdir - path + 1;
tmp = xstrndup(path, *dir_len);
*dir_found = !lstat(tmp, &st);
free(tmp);
return 0;
}
void clear_skip_worktree_from_present_files(struct index_state *istate)
{
const char *last_dirname = NULL;
size_t dir_len = 0;
int dir_found = 1;
int i;
int path_count[2] = {0, 0};
int restarted = 0;
if (!core_apply_sparse_checkout ||
sparse_expect_files_outside_of_patterns)
return;
trace2_region_enter("index", "clear_skip_worktree_from_present_files",
istate->repo);
restart:
for (i = 0; i < istate->cache_nr; i++) {
struct cache_entry *ce = istate->cache[i];
if (ce_skip_worktree(ce)) {
path_count[restarted]++;
if (path_found(ce->name, &last_dirname, &dir_len, &dir_found)) {
if (S_ISSPARSEDIR(ce->ce_mode)) {
if (restarted)
BUG("ensure-full-index did not fully flatten?");
ensure_full_index(istate);
restarted = 1;
goto restart;
}
ce->ce_flags &= ~CE_SKIP_WORKTREE;
}
}
}
if (path_count[0])
trace2_data_intmax("index", istate->repo,
"sparse_path_count", path_count[0]);
if (restarted)
trace2_data_intmax("index", istate->repo,
"sparse_path_count_full", path_count[1]);
trace2_region_leave("index", "clear_skip_worktree_from_present_files",
istate->repo);
}
/*
* 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;
}