Thanks to visit codestin.com
Credit goes to github.com

Skip to content

add VM Lock around rb_const_remove operations (Module#remove_const) #13717

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: master
Choose a base branch
from
Open

add VM Lock around rb_const_remove operations (Module#remove_const) #13717

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
c3420bf
add VM Lock around `rb_const_remove` operations (Module#remove_const)
luke-gruber Jun 26, 2025
7a651bc
Ractors: fixes for parallel const_set/remove_const and const_get
luke-gruber Jun 30, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion constant.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,7 @@ void rb_free_const_table(struct rb_id_table *tbl);
VALUE rb_const_source_location(VALUE, ID);

int rb_autoloading_value(VALUE mod, ID id, VALUE *value, rb_const_flag_t *flag);
rb_const_entry_t *rb_const_lookup(VALUE klass, ID id);
rb_const_entry_t *rb_const_lookup(VALUE klass, ID id, rb_const_entry_t *entry_out);
VALUE rb_public_const_get_at(VALUE klass, ID id);
VALUE rb_public_const_get_from(VALUE klass, ID id);
int rb_public_const_defined_from(VALUE klass, ID id);
Expand Down
163 changes: 94 additions & 69 deletions variable.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3023,9 +3023,10 @@ static VALUE
autoload_synchronized(VALUE _arguments)
{
struct autoload_arguments *arguments = (struct autoload_arguments *)_arguments;
rb_const_entry_t constant_entry = {0};

rb_const_entry_t *constant_entry = rb_const_lookup(arguments->module, arguments->name);
if (constant_entry && !UNDEF_P(constant_entry->value)) {
rb_const_entry_t *ce = rb_const_lookup(arguments->module, arguments->name, &constant_entry);
if (ce && !UNDEF_P(constant_entry.value)) {
return Qfalse;
}

Expand Down Expand Up @@ -3226,13 +3227,15 @@ autoloading_const_entry(VALUE mod, ID id)
return 0;
}


static int
autoload_defined_p(VALUE mod, ID id)
{
rb_const_entry_t *ce = rb_const_lookup(mod, id);
rb_const_entry_t ce_out = {0};
rb_const_entry_t *ce = rb_const_lookup(mod, id, &ce_out);

// If there is no constant or the constant is not undefined (special marker for autoloading):
if (!ce || !UNDEF_P(ce->value)) {
if (!ce || !UNDEF_P(ce_out.value)) {
// We are not autoloading:
return 0;
}
Expand Down Expand Up @@ -3421,11 +3424,12 @@ autoload_try_load(VALUE _arguments)
struct autoload_load_arguments *arguments = (struct autoload_load_arguments*)_arguments;

VALUE result = autoload_feature_require(_arguments);
rb_const_entry_t ce_out = {0};

// After we loaded the feature, if the constant is not defined, we remove it completely:
rb_const_entry_t *ce = rb_const_lookup(arguments->module, arguments->name);
rb_const_entry_t *ce = rb_const_lookup(arguments->module, arguments->name, &ce_out);

if (!ce || UNDEF_P(ce->value)) {
if (!ce || UNDEF_P(ce_out.value)) {
result = Qfalse;

rb_const_remove(arguments->module, arguments->name);
Expand Down Expand Up @@ -3457,10 +3461,11 @@ autoload_try_load(VALUE _arguments)
VALUE
rb_autoload_load(VALUE module, ID name)
{
rb_const_entry_t *ce = rb_const_lookup(module, name);
rb_const_entry_t ce_out = {0};
rb_const_entry_t *ce = rb_const_lookup(module, name, &ce_out);

// We bail out as early as possible without any synchronisation:
if (!ce || !UNDEF_P(ce->value)) {
if (!ce || !UNDEF_P(ce_out.value)) {
return Qfalse;
}

Expand All @@ -3478,7 +3483,7 @@ rb_autoload_load(VALUE module, ID name)
// This confirms whether autoloading is required or not:
if (autoload_const_value == Qfalse) return autoload_const_value;

arguments.flag = ce->flag & (CONST_DEPRECATED | CONST_VISIBILITY_MASK);
arguments.flag = ce_out.flag & (CONST_DEPRECATED | CONST_VISIBILITY_MASK);

// Only one thread will enter here at a time:
VALUE result = rb_mutex_synchronize(arguments.mutex, autoload_try_load, (VALUE)&arguments);
Expand Down Expand Up @@ -3549,6 +3554,7 @@ rb_const_search_from(VALUE klass, ID id, int exclude, int recurse, int visibilit
{
VALUE value, current;
bool first_iteration = true;
rb_const_entry_t ce_out = {0};

for (current = klass;
RTEST(current);
Expand All @@ -3570,13 +3576,13 @@ rb_const_search_from(VALUE klass, ID id, int exclude, int recurse, int visibilit
if (BUILTIN_TYPE(tmp) == T_ICLASS) tmp = RBASIC(tmp)->klass;

// Do the lookup. Loop in case of autoload.
while ((ce = rb_const_lookup(tmp, id))) {
if (visibility && RB_CONST_PRIVATE_P(ce)) {
while ((ce = rb_const_lookup(tmp, id, &ce_out))) {
if (visibility && RB_CONST_PRIVATE_P(&ce_out)) {
GET_EC()->private_const_reference = tmp;
return Qundef;
}
rb_const_warn_if_deprecated(ce, tmp, id);
value = ce->value;
rb_const_warn_if_deprecated(&ce_out, tmp, id);
value = ce_out.value;
if (UNDEF_P(value)) {
struct autoload_const *ac;
if (am == tmp) break;
Expand Down Expand Up @@ -3656,16 +3662,17 @@ rb_const_location_from(VALUE klass, ID id, int exclude, int recurse, int visibil
{
while (RTEST(klass)) {
rb_const_entry_t *ce;
rb_const_entry_t ce_out = {0};

while ((ce = rb_const_lookup(klass, id))) {
if (visibility && RB_CONST_PRIVATE_P(ce)) {
while ((ce = rb_const_lookup(klass, id, &ce_out))) {
if (visibility && RB_CONST_PRIVATE_P(&ce_out)) {
return Qnil;
}
if (exclude && klass == rb_cObject) {
goto not_found;
}

if (UNDEF_P(ce->value)) { // autoload
if (UNDEF_P(ce_out.value)) { // autoload
VALUE autoload_const_value = autoload_data(klass, id);
if (RTEST(autoload_const_value)) {
struct autoload_const *autoload_const;
Expand All @@ -3677,8 +3684,8 @@ rb_const_location_from(VALUE klass, ID id, int exclude, int recurse, int visibil
}
}

if (NIL_P(ce->file)) return rb_ary_new();
return rb_assoc_new(ce->file, INT2NUM(ce->line));
if (NIL_P(ce_out.file)) return rb_ary_new();
return rb_assoc_new(ce_out.file, INT2NUM(ce_out.line));
}
if (!recurse) break;
klass = RCLASS_SUPER(klass);
Expand Down Expand Up @@ -3735,39 +3742,42 @@ rb_mod_remove_const(VALUE mod, VALUE name)
return rb_const_remove(mod, id);
}

static rb_const_entry_t * const_lookup(struct rb_id_table *tbl, ID id);
static rb_const_entry_t * const_lookup(struct rb_id_table *tbl, ID id, rb_const_entry_t *ce_out);

VALUE
rb_const_remove(VALUE mod, ID id)
{
VALUE val;
rb_const_entry_t *ce;
rb_const_entry_t ce_out = {0};

rb_check_frozen(mod);

ce = rb_const_lookup(mod, id);
if (!ce || !rb_id_table_delete(RCLASS_WRITABLE_CONST_TBL(mod), id)) {
if (rb_const_defined_at(mod, id)) {
rb_name_err_raise("cannot remove %2$s::%1$s", mod, ID2SYM(id));
}
RB_VM_LOCKING() {
ce = rb_const_lookup(mod, id, &ce_out);
if (!ce || !rb_id_table_delete(RCLASS_WRITABLE_CONST_TBL(mod), id)) {
if (rb_const_defined_at(mod, id)) {
rb_name_err_raise("cannot remove %2$s::%1$s", mod, ID2SYM(id));
}

undefined_constant(mod, ID2SYM(id));
}
undefined_constant(mod, ID2SYM(id));
}

rb_const_warn_if_deprecated(ce, mod, id);
rb_clear_constant_cache_for_id(id);
rb_const_warn_if_deprecated(ce, mod, id);
rb_clear_constant_cache_for_id(id);

val = ce->value;
val = ce_out.value;

if (UNDEF_P(val)) {
autoload_delete(mod, id);
val = Qnil;
}
if (UNDEF_P(val)) {
autoload_delete(mod, id);
val = Qnil;
}

if (ce != const_lookup(RCLASS_PRIME_CONST_TBL(mod), id)) {
ruby_xfree(ce);
if (ce != const_lookup(RCLASS_PRIME_CONST_TBL(mod), id, NULL)) {
ruby_xfree(ce);
}
// else - skip free'ing the ce because it still exists in the prime classext
}
// else - skip free'ing the ce because it still exists in the prime classext

return val;
}
Expand Down Expand Up @@ -3907,15 +3917,16 @@ rb_const_defined_0(VALUE klass, ID id, int exclude, int recurse, int visibility)
VALUE tmp;
int mod_retry = 0;
rb_const_entry_t *ce;
rb_const_entry_t ce_out = {0};

tmp = klass;
retry:
while (tmp) {
if ((ce = rb_const_lookup(tmp, id))) {
if (visibility && RB_CONST_PRIVATE_P(ce)) {
if ((ce = rb_const_lookup(tmp, id, &ce_out))) {
if (visibility && RB_CONST_PRIVATE_P(&ce_out)) {
return (int)Qfalse;
}
if (UNDEF_P(ce->value) && !check_autoload_required(tmp, id, 0) &&
if (UNDEF_P(ce_out.value) && !check_autoload_required(tmp, id, 0) &&
!rb_autoloading_value(tmp, id, NULL, NULL))
return (int)Qfalse;

Expand Down Expand Up @@ -4043,8 +4054,8 @@ const_set(VALUE klass, ID id, VALUE val)
RCLASS_WRITE_CONST_TBL(klass, tbl, false);
rb_clear_constant_cache_for_id(id);
ce = ZALLOC(rb_const_entry_t);
rb_id_table_insert(tbl, id, (VALUE)ce);
setup_const_entry(ce, klass, val, CONST_PUBLIC);
rb_id_table_insert(tbl, id, (VALUE)ce);
}
else {
struct autoload_const ac = {
Expand All @@ -4057,6 +4068,7 @@ const_set(VALUE klass, ID id, VALUE val)
}
}

// TODO: I think this needs to be locked
/*
* Resolve and cache class name immediately to resolve ambiguity
* and avoid order-dependency on const_tbl
Expand Down Expand Up @@ -4121,6 +4133,8 @@ const_tbl_update(struct autoload_const *ac, int autoload_force)
rb_const_flag_t visibility = ac->flag;
rb_const_entry_t *ce;

ASSERT_vm_locking();

if (rb_id_table_lookup(tbl, id, &value)) {
ce = (rb_const_entry_t *)value;
if (UNDEF_P(ce->value)) {
Expand Down Expand Up @@ -4167,8 +4181,8 @@ const_tbl_update(struct autoload_const *ac, int autoload_force)
rb_clear_constant_cache_for_id(id);

ce = ZALLOC(rb_const_entry_t);
rb_id_table_insert(tbl, id, (VALUE)ce);
setup_const_entry(ce, klass, val, visibility);
rb_id_table_insert(tbl, id, (VALUE)ce);
}
}

Expand Down Expand Up @@ -4216,29 +4230,31 @@ set_const_visibility(VALUE mod, int argc, const VALUE *argv,
return;
}

for (i = 0; i < argc; i++) {
struct autoload_const *ac;
VALUE val = argv[i];
id = rb_check_id(&val);
if (!id) {
undefined_constant(mod, val);
}
if ((ce = rb_const_lookup(mod, id))) {
ce->flag &= ~mask;
ce->flag |= flag;
if (UNDEF_P(ce->value)) {
struct autoload_data *ele;

ele = autoload_data_for_named_constant(mod, id, &ac);
if (ele) {
ac->flag &= ~mask;
ac->flag |= flag;
RB_VM_LOCKING() {
for (i = 0; i < argc; i++) {
struct autoload_const *ac;
VALUE val = argv[i];
id = rb_check_id(&val);
if (!id) {
undefined_constant(mod, val);
}
if ((ce = rb_const_lookup(mod, id, NULL))) {
ce->flag &= ~mask;
ce->flag |= flag;
if (UNDEF_P(ce->value)) {
struct autoload_data *ele;

ele = autoload_data_for_named_constant(mod, id, &ac);
if (ele) {
ac->flag &= ~mask;
ac->flag |= flag;
}
}
rb_clear_constant_cache_for_id(id);
}
else {
undefined_constant(mod, ID2SYM(id));
}
rb_clear_constant_cache_for_id(id);
}
else {
undefined_constant(mod, ID2SYM(id));
}
}
}
Expand All @@ -4254,10 +4270,12 @@ rb_deprecate_constant(VALUE mod, const char *name)
if (!(id = rb_check_id_cstr(name, len, NULL))) {
undefined_constant(mod, rb_fstring_new(name, len));
}
if (!(ce = rb_const_lookup(mod, id))) {
undefined_constant(mod, ID2SYM(id));
RB_VM_LOCKING() {
if (!(ce = rb_const_lookup(mod, id, NULL))) {
undefined_constant(mod, ID2SYM(id));
}
ce->flag |= CONST_DEPRECATED;
}
ce->flag |= CONST_DEPRECATED;
}

/*
Expand Down Expand Up @@ -4810,23 +4828,30 @@ rb_fields_tbl_copy(VALUE dst, VALUE src)
}

static rb_const_entry_t *
const_lookup(struct rb_id_table *tbl, ID id)
const_lookup(struct rb_id_table *tbl, ID id, rb_const_entry_t *entry_out)
{
if (tbl) {
rb_const_entry_t *ce;
VALUE val;
bool r;
RB_VM_LOCKING() {
r = rb_id_table_lookup(tbl, id, &val);
if (r) {
ce = (rb_const_entry_t*)val;
if (entry_out) *entry_out = *ce;
}
}

if (r) return (rb_const_entry_t *)val;
if (r) {
return ce;
}
}
return NULL;
}

rb_const_entry_t *
rb_const_lookup(VALUE klass, ID id)
rb_const_lookup(VALUE klass, ID id, rb_const_entry_t *entry_out)
{
return const_lookup(RCLASS_CONST_TBL(klass), id);
return const_lookup(RCLASS_CONST_TBL(klass), id, entry_out);
}

7 changes: 4 additions & 3 deletions vm_insnhelper.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1091,10 +1091,11 @@ vm_get_ev_const(rb_execution_context_t *ec, VALUE orig_klass, ID id, bool allow_
if (!NIL_P(klass)) {
VALUE av, am = 0;
rb_const_entry_t *ce;
rb_const_entry_t ce_out = {0};
search_continue:
if ((ce = rb_const_lookup(klass, id))) {
rb_const_warn_if_deprecated(ce, klass, id);
val = ce->value;
if ((ce = rb_const_lookup(klass, id, &ce_out))) {
rb_const_warn_if_deprecated(&ce_out, klass, id);
val = ce_out.value;
if (UNDEF_P(val)) {
if (am == klass) break;
am = klass;
Expand Down
Loading