Commit 9bc42227 authored by Junio C Hamano's avatar Junio C Hamano

Merge branch 'jk/faster-name-conflicts'

Optimize the check to see if a ref $F can be created by making sure
no existing ref has $F/ as its prefix, which especially matters in
a repository with a large number of existing refs.

* jk/faster-name-conflicts:
  refs: speed up is_refname_available
parents 69a5bbbb cbe73331
......@@ -784,37 +784,32 @@ static void prime_ref_dir(struct ref_dir *dir)
prime_ref_dir(get_ref_dir(entry));
}
}
/*
* Return true iff refname1 and refname2 conflict with each other.
* Two reference names conflict if one of them exactly matches the
* leading components of the other; e.g., "foo/bar" conflicts with
* both "foo" and with "foo/bar/baz" but not with "foo/bar" or
* "foo/barbados".
*/
static int names_conflict(const char *refname1, const char *refname2)
static int entry_matches(struct ref_entry *entry, const char *refname)
{
for (; *refname1 && *refname1 == *refname2; refname1++, refname2++)
;
return (*refname1 == '\0' && *refname2 == '/')
|| (*refname1 == '/' && *refname2 == '\0');
return refname && !strcmp(entry->name, refname);
}
struct name_conflict_cb {
const char *refname;
const char *oldrefname;
const char *conflicting_refname;
struct nonmatching_ref_data {
const char *skip;
struct ref_entry *found;
};
static int name_conflict_fn(struct ref_entry *entry, void *cb_data)
static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
{
struct name_conflict_cb *data = (struct name_conflict_cb *)cb_data;
if (data->oldrefname && !strcmp(data->oldrefname, entry->name))
struct nonmatching_ref_data *data = vdata;
if (entry_matches(entry, data->skip))
return 0;
if (names_conflict(data->refname, entry->name)) {
data->conflicting_refname = entry->name;
data->found = entry;
return 1;
}
return 0;
}
static void report_refname_conflict(struct ref_entry *entry,
const char *refname)
{
error("'%s' exists; cannot create '%s'", entry->name, refname);
}
/*
......@@ -823,21 +818,84 @@ static int name_conflict_fn(struct ref_entry *entry, void *cb_data)
* oldrefname is non-NULL, ignore potential conflicts with oldrefname
* (e.g., because oldrefname is scheduled for deletion in the same
* operation).
*
* Two reference names conflict if one of them exactly matches the
* leading components of the other; e.g., "foo/bar" conflicts with
* both "foo" and with "foo/bar/baz" but not with "foo/bar" or
* "foo/barbados".
*/
static int is_refname_available(const char *refname, const char *oldrefname,
struct ref_dir *dir)
{
struct name_conflict_cb data;
data.refname = refname;
data.oldrefname = oldrefname;
data.conflicting_refname = NULL;
const char *slash;
size_t len;
int pos;
char *dirname;
for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
/*
* We are still at a leading dir of the refname; we are
* looking for a conflict with a leaf entry.
*
* If we find one, we still must make sure it is
* not "oldrefname".
*/
pos = search_ref_dir(dir, refname, slash - refname);
if (pos >= 0) {
struct ref_entry *entry = dir->entries[pos];
if (entry_matches(entry, oldrefname))
return 1;
report_refname_conflict(entry, refname);
return 0;
}
/*
* Otherwise, we can try to continue our search with
* the next component; if we come up empty, we know
* there is nothing under this whole prefix.
*/
pos = search_ref_dir(dir, refname, slash + 1 - refname);
if (pos < 0)
return 1;
dir = get_ref_dir(dir->entries[pos]);
}
/*
* We are at the leaf of our refname; we want to
* make sure there are no directories which match it.
*/
len = strlen(refname);
dirname = xmallocz(len + 1);
sprintf(dirname, "%s/", refname);
pos = search_ref_dir(dir, dirname, len + 1);
free(dirname);
if (pos >= 0) {
/*
* We found a directory named "refname". It is a
* problem iff it contains any ref that is not
* "oldrefname".
*/
struct ref_entry *entry = dir->entries[pos];
struct ref_dir *dir = get_ref_dir(entry);
struct nonmatching_ref_data data;
data.skip = oldrefname;
sort_ref_dir(dir);
if (do_for_each_entry_in_dir(dir, 0, name_conflict_fn, &data)) {
error("'%s' exists; cannot create '%s'",
data.conflicting_refname, refname);
if (!do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data))
return 1;
report_refname_conflict(data.found, refname);
return 0;
}
/*
* There is no point in searching for another leaf
* node which matches it; such an entry would be the
* ref we are looking for, not a conflict.
*/
return 1;
}
......
......@@ -11,7 +11,9 @@ semantic is still the same.
'
. ./test-lib.sh
echo '[core] logallrefupdates = true' >>.git/config
test_expect_success 'enable reflogs' '
git config core.logallrefupdates true
'
test_expect_success \
'prepare a trivial repository' \
......@@ -158,4 +160,31 @@ test_expect_success 'pack ref directly below refs/' '
test_path_is_missing .git/refs/top
'
test_expect_success 'disable reflogs' '
git config core.logallrefupdates false &&
rm -rf .git/logs
'
test_expect_success 'create packed foo/bar/baz branch' '
git branch foo/bar/baz &&
git pack-refs --all --prune &&
test_path_is_missing .git/refs/heads/foo/bar/baz &&
test_path_is_missing .git/logs/refs/heads/foo/bar/baz
'
test_expect_success 'notice d/f conflict with existing directory' '
test_must_fail git branch foo &&
test_must_fail git branch foo/bar
'
test_expect_success 'existing directory reports concrete ref' '
test_must_fail git branch foo 2>stderr &&
grep refs/heads/foo/bar/baz stderr
'
test_expect_success 'notice d/f conflict with existing ref' '
test_must_fail git branch foo/bar/baz/extra &&
test_must_fail git branch foo/bar/baz/lots/of/extra/components
'
test_done
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