/* Type object implementation */

#include "Python.h"

#include "pycore_abstract.h" // _PySequence_IterSearch()

#include "pycore_call.h" // _PyObject_VectorcallTstate()

#include "pycore_code.h" // CO_FAST_FREE

#include "pycore_dict.h" // _PyDict_KeysSize()

#include "pycore_frame.h" // _PyInterpreterFrame

#include "pycore_lock.h" // _PySeqLock_*

#include "pycore_long.h" // _PyLong_IsNegative()

#include "pycore_memoryobject.h" // _PyMemoryView_FromBufferProc()

#include "pycore_modsupport.h" // _PyArg_NoKwnames()

#include "pycore_moduleobject.h" // _PyModule_GetDef()

#include "pycore_object.h" // _PyType_HasFeature()

#include "pycore_object_alloc.h" // _PyObject_MallocWithType()

#include "pycore_pyerrors.h" // _PyErr_Occurred()

#include "pycore_pystate.h" // _PyThreadState_GET()

#include "pycore_symtable.h" // _Py_Mangle()

#include "pycore_typeobject.h" // struct type_cache

#include "pycore_unionobject.h" // _Py_union_type_or

#include "pycore_weakref.h" // _PyWeakref_GET_REF()

#include "opcode.h" // MAKE_CELL

#include <stddef.h> // ptrdiff_t

/*[clinic input]

class type "PyTypeObject *" "&PyType_Type"

class object "PyObject *" "&PyBaseObject_Type"

[clinic start generated code]*/

/*[clinic end generated code: output=da39a3ee5e6b4b0d input=4b94608d231c434b]*/

#include "clinic/typeobject.c.h"

/* Support type attribute lookup cache */

/* The cache can keep references to the names alive for longer than

they normally would. This is why the maximum size is limited to

MCACHE_MAX_ATTR_SIZE, since it might be a problem if very large

strings are used as attribute names. */

#define MCACHE_MAX_ATTR_SIZE 100

#define MCACHE_HASH(version, name_hash) \

(((unsigned int)(version) ^ (unsigned int)(name_hash)) \

& ((1 << MCACHE_SIZE_EXP) - 1))

#define MCACHE_HASH_METHOD(type, name) \

MCACHE_HASH(FT_ATOMIC_LOAD_UINT32_RELAXED((type)->tp_version_tag), \

((Py_ssize_t)(name)) >> 3)

#define MCACHE_CACHEABLE_NAME(name) \

PyUnicode_CheckExact(name) && \

PyUnicode_IS_READY(name) && \

(PyUnicode_GET_LENGTH(name) <= MCACHE_MAX_ATTR_SIZE)

#define NEXT_GLOBAL_VERSION_TAG _PyRuntime.types.next_version_tag

#define NEXT_VERSION_TAG(interp) \

(interp)->types.next_version_tag

#ifdef Py_GIL_DISABLED

// There's a global lock for mutation of types. This avoids having to take

// additional locks while doing various subclass processing which may result

// in odd behaviors w.r.t. running with the GIL as the outer type lock could

// be released and reacquired during a subclass update if there's contention

// on the subclass lock.

#define TYPE_LOCK &PyInterpreterState_Get()->types.mutex

#define BEGIN_TYPE_LOCK() Py_BEGIN_CRITICAL_SECTION_MUT(TYPE_LOCK)

#define END_TYPE_LOCK() Py_END_CRITICAL_SECTION()

#define BEGIN_TYPE_DICT_LOCK(d) \

Py_BEGIN_CRITICAL_SECTION2_MUT(TYPE_LOCK, &_PyObject_CAST(d)->ob_mutex)

#define END_TYPE_DICT_LOCK() Py_END_CRITICAL_SECTION2()

#define ASSERT_TYPE_LOCK_HELD() \

_Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(TYPE_LOCK)

#else

#define BEGIN_TYPE_LOCK()

#define END_TYPE_LOCK()

#define BEGIN_TYPE_DICT_LOCK(d)

#define END_TYPE_DICT_LOCK()

#define ASSERT_TYPE_LOCK_HELD()

#endif

typedef struct PySlot_Offset {

short subslot_offset;

short slot_offset;

} PySlot_Offset;

static void

slot_bf_releasebuffer(PyObject *self, Py_buffer *buffer);

static void

releasebuffer_call_python(PyObject *self, Py_buffer *buffer);

static PyObject *

slot_tp_new(PyTypeObject *type, PyObject *args, PyObject *kwds);

static PyObject *

lookup_maybe_method(PyObject *self, PyObject *attr, int *unbound);

static int

slot_tp_setattro(PyObject *self, PyObject *name, PyObject *value);

static inline PyTypeObject *

type_from_ref(PyObject *ref)

{

PyObject *obj = _PyWeakref_GET_REF(ref);

if (obj == NULL) {

return NULL;

}

return _PyType_CAST(obj);

}

/* helpers for for static builtin types */

#ifndef NDEBUG

static inline int

managed_static_type_index_is_set(PyTypeObject *self)

{

return self->tp_subclasses != NULL;

}

#endif

static inline size_t

managed_static_type_index_get(PyTypeObject *self)

{

assert(managed_static_type_index_is_set(self));

/* We store a 1-based index so 0 can mean "not initialized". */

return (size_t)self->tp_subclasses - 1;

}

static inline void

managed_static_type_index_set(PyTypeObject *self, size_t index)

{

assert(index < _Py_MAX_MANAGED_STATIC_BUILTIN_TYPES);

/* We store a 1-based index so 0 can mean "not initialized". */

self->tp_subclasses = (PyObject *)(index + 1);

}

static inline void

managed_static_type_index_clear(PyTypeObject *self)

{

self->tp_subclasses = NULL;

}

static PyTypeObject *

static_ext_type_lookup(PyInterpreterState *interp, size_t index,

int64_t *p_interp_count)

{

assert(interp->runtime == &_PyRuntime);

assert(index < _Py_MAX_MANAGED_STATIC_EXT_TYPES);

size_t full_index = index + _Py_MAX_MANAGED_STATIC_BUILTIN_TYPES;

int64_t interp_count =

_PyRuntime.types.managed_static.types[full_index].interp_count;

assert((interp_count == 0) ==

(_PyRuntime.types.managed_static.types[full_index].type == NULL));

*p_interp_count = interp_count;

PyTypeObject *type = interp->types.for_extensions.initialized[index].type;

if (type == NULL) {

return NULL;

}

assert(!interp->types.for_extensions.initialized[index].isbuiltin);

assert(type == _PyRuntime.types.managed_static.types[full_index].type);

assert(managed_static_type_index_is_set(type));

return type;

}

static managed_static_type_state *

managed_static_type_state_get(PyInterpreterState *interp, PyTypeObject *self)

{

// It's probably a builtin type.

size_t index = managed_static_type_index_get(self);

managed_static_type_state *state =

&(interp->types.builtins.initialized[index]);

if (state->type == self) {

return state;

}

if (index > _Py_MAX_MANAGED_STATIC_EXT_TYPES) {

return state;

}

return &(interp->types.for_extensions.initialized[index]);

}

/* For static types we store some state in an array on each interpreter. */

managed_static_type_state *

_PyStaticType_GetState(PyInterpreterState *interp, PyTypeObject *self)

{

assert(self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN);

return managed_static_type_state_get(interp, self);

}

/* Set the type's per-interpreter state. */

static void

managed_static_type_state_init(PyInterpreterState *interp, PyTypeObject *self,

int isbuiltin, int initial)

{

assert(interp->runtime == &_PyRuntime);

size_t index;

if (initial) {

assert(!managed_static_type_index_is_set(self));

if (isbuiltin) {

index = interp->types.builtins.num_initialized;

assert(index < _Py_MAX_MANAGED_STATIC_BUILTIN_TYPES);

}

else {

PyMutex_Lock(&interp->types.mutex);

index = interp->types.for_extensions.next_index;

interp->types.for_extensions.next_index++;

PyMutex_Unlock(&interp->types.mutex);

assert(index < _Py_MAX_MANAGED_STATIC_EXT_TYPES);

}

managed_static_type_index_set(self, index);

}

else {

index = managed_static_type_index_get(self);

if (isbuiltin) {

assert(index == interp->types.builtins.num_initialized);

assert(index < _Py_MAX_MANAGED_STATIC_BUILTIN_TYPES);

}

else {

assert(index < _Py_MAX_MANAGED_STATIC_EXT_TYPES);

}

}

size_t full_index = isbuiltin

? index

: index + _Py_MAX_MANAGED_STATIC_BUILTIN_TYPES;

assert((initial == 1) ==

(_PyRuntime.types.managed_static.types[full_index].interp_count == 0));

(void)_Py_atomic_add_int64(

&_PyRuntime.types.managed_static.types[full_index].interp_count, 1);

if (initial) {

assert(_PyRuntime.types.managed_static.types[full_index].type == NULL);

_PyRuntime.types.managed_static.types[full_index].type = self;

}

else {

assert(_PyRuntime.types.managed_static.types[full_index].type == self);

}

managed_static_type_state *state = isbuiltin

? &(interp->types.builtins.initialized[index])

: &(interp->types.for_extensions.initialized[index]);

/* It should only be called once for each builtin type per interpreter. */

assert(state->type == NULL);

state->type = self;

state->isbuiltin = isbuiltin;

/* state->tp_subclasses is left NULL until init_subclasses() sets it. */

/* state->tp_weaklist is left NULL until insert_head() or insert_after()

(in weakrefobject.c) sets it. */

if (isbuiltin) {

interp->types.builtins.num_initialized++;

}

else {

interp->types.for_extensions.num_initialized++;

}

}

/* Reset the type's per-interpreter state.

This basically undoes what managed_static_type_state_init() did. */

static void

managed_static_type_state_clear(PyInterpreterState *interp, PyTypeObject *self,

int isbuiltin, int final)

{

size_t index = managed_static_type_index_get(self);

size_t full_index = isbuiltin

? index

: index + _Py_MAX_MANAGED_STATIC_BUILTIN_TYPES;

managed_static_type_state *state = isbuiltin

? &(interp->types.builtins.initialized[index])

: &(interp->types.for_extensions.initialized[index]);

assert(state != NULL);

assert(_PyRuntime.types.managed_static.types[full_index].interp_count > 0);

assert(_PyRuntime.types.managed_static.types[full_index].type == state->type);

assert(state->type != NULL);

state->type = NULL;

assert(state->tp_weaklist == NULL); // It was already cleared out.

(void)_Py_atomic_add_int64(

&_PyRuntime.types.managed_static.types[full_index].interp_count, -1);

if (final) {

assert(!_PyRuntime.types.managed_static.types[full_index].interp_count);

_PyRuntime.types.managed_static.types[full_index].type = NULL;

managed_static_type_index_clear(self);

}

if (isbuiltin) {

assert(interp->types.builtins.num_initialized > 0);

interp->types.builtins.num_initialized--;

}

else {

PyMutex_Lock(&interp->types.mutex);

assert(interp->types.for_extensions.num_initialized > 0);

interp->types.for_extensions.num_initialized--;

if (interp->types.for_extensions.num_initialized == 0) {

interp->types.for_extensions.next_index = 0;

}

PyMutex_Unlock(&interp->types.mutex);

}

}

// Also see _PyStaticType_InitBuiltin() and _PyStaticType_FiniBuiltin().

/* end static builtin helpers */

static inline void

start_readying(PyTypeObject *type)

{

if (type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

PyInterpreterState *interp = _PyInterpreterState_GET();

managed_static_type_state *state = managed_static_type_state_get(interp, type);

assert(state != NULL);

assert(!state->readying);

state->readying = 1;

return;

}

assert((type->tp_flags & Py_TPFLAGS_READYING) == 0);

type->tp_flags |= Py_TPFLAGS_READYING;

}

static inline void

stop_readying(PyTypeObject *type)

{

if (type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

PyInterpreterState *interp = _PyInterpreterState_GET();

managed_static_type_state *state = managed_static_type_state_get(interp, type);

assert(state != NULL);

assert(state->readying);

state->readying = 0;

return;

}

assert(type->tp_flags & Py_TPFLAGS_READYING);

type->tp_flags &= ~Py_TPFLAGS_READYING;

}

static inline int

is_readying(PyTypeObject *type)

{

if (type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

PyInterpreterState *interp = _PyInterpreterState_GET();

managed_static_type_state *state = managed_static_type_state_get(interp, type);

assert(state != NULL);

return state->readying;

}

return (type->tp_flags & Py_TPFLAGS_READYING) != 0;

}

/* accessors for objects stored on PyTypeObject */

static inline PyObject *

lookup_tp_dict(PyTypeObject *self)

{

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

PyInterpreterState *interp = _PyInterpreterState_GET();

managed_static_type_state *state = _PyStaticType_GetState(interp, self);

assert(state != NULL);

return state->tp_dict;

}

return self->tp_dict;

}

PyObject *

_PyType_GetDict(PyTypeObject *self)

{

/* It returns a borrowed reference. */

return lookup_tp_dict(self);

}

PyObject *

PyType_GetDict(PyTypeObject *self)

{

PyObject *dict = lookup_tp_dict(self);

return _Py_XNewRef(dict);

}

static inline void

set_tp_dict(PyTypeObject *self, PyObject *dict)

{

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

PyInterpreterState *interp = _PyInterpreterState_GET();

managed_static_type_state *state = _PyStaticType_GetState(interp, self);

assert(state != NULL);

state->tp_dict = dict;

return;

}

self->tp_dict = dict;

}

static inline void

clear_tp_dict(PyTypeObject *self)

{

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

PyInterpreterState *interp = _PyInterpreterState_GET();

managed_static_type_state *state = _PyStaticType_GetState(interp, self);

assert(state != NULL);

Py_CLEAR(state->tp_dict);

return;

}

Py_CLEAR(self->tp_dict);

}

static inline PyObject *

lookup_tp_bases(PyTypeObject *self)

{

return self->tp_bases;

}

PyObject *

_PyType_GetBases(PyTypeObject *self)

{

PyObject *res;

BEGIN_TYPE_LOCK();

res = lookup_tp_bases(self);

Py_INCREF(res);

END_TYPE_LOCK();

return res;

}

static inline void

set_tp_bases(PyTypeObject *self, PyObject *bases, int initial)

{

assert(PyTuple_Check(bases));

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

// XXX tp_bases can probably be statically allocated for each

// static builtin type.

assert(PyTuple_CheckExact(bases));

assert(initial);

assert(self->tp_bases == NULL);

if (PyTuple_GET_SIZE(bases) == 0) {

assert(self->tp_base == NULL);

}

else {

assert(PyTuple_GET_SIZE(bases) == 1);

assert(PyTuple_GET_ITEM(bases, 0) == (PyObject *)self->tp_base);

assert(self->tp_base->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN);

assert(_Py_IsImmortalLoose(self->tp_base));

}

_Py_SetImmortal(bases);

}

self->tp_bases = bases;

}

static inline void

clear_tp_bases(PyTypeObject *self, int final)

{

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

if (final) {

if (self->tp_bases != NULL) {

if (PyTuple_GET_SIZE(self->tp_bases) == 0) {

Py_CLEAR(self->tp_bases);

}

else {

assert(_Py_IsImmortalLoose(self->tp_bases));

_Py_ClearImmortal(self->tp_bases);

}

}

}

return;

}

Py_CLEAR(self->tp_bases);

}

static inline PyObject *

lookup_tp_mro(PyTypeObject *self)

{

ASSERT_TYPE_LOCK_HELD();

return self->tp_mro;

}

PyObject *

_PyType_GetMRO(PyTypeObject *self)

{

#ifdef Py_GIL_DISABLED

PyObject *mro = _Py_atomic_load_ptr_relaxed(&self->tp_mro);

if (mro == NULL) {

return NULL;

}

if (_Py_TryIncrefCompare(&self->tp_mro, mro)) {

return mro;

}

BEGIN_TYPE_LOCK();

mro = lookup_tp_mro(self);

Py_XINCREF(mro);

END_TYPE_LOCK();

return mro;

#else

return Py_XNewRef(lookup_tp_mro(self));

#endif

}

static inline void

set_tp_mro(PyTypeObject *self, PyObject *mro, int initial)

{

assert(PyTuple_CheckExact(mro));

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

// XXX tp_mro can probably be statically allocated for each

// static builtin type.

assert(initial);

assert(self->tp_mro == NULL);

/* Other checks are done via set_tp_bases. */

_Py_SetImmortal(mro);

}

self->tp_mro = mro;

}

static inline void

clear_tp_mro(PyTypeObject *self, int final)

{

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

if (final) {

if (self->tp_mro != NULL) {

if (PyTuple_GET_SIZE(self->tp_mro) == 0) {

Py_CLEAR(self->tp_mro);

}

else {

assert(_Py_IsImmortalLoose(self->tp_mro));

_Py_ClearImmortal(self->tp_mro);

}

}

}

return;

}

Py_CLEAR(self->tp_mro);

}

static PyObject *

init_tp_subclasses(PyTypeObject *self)

{

PyObject *subclasses = PyDict_New();

if (subclasses == NULL) {

return NULL;

}

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

PyInterpreterState *interp = _PyInterpreterState_GET();

managed_static_type_state *state = _PyStaticType_GetState(interp, self);

state->tp_subclasses = subclasses;

return subclasses;

}

self->tp_subclasses = (void *)subclasses;

return subclasses;

}

static void

clear_tp_subclasses(PyTypeObject *self)

{

/* Delete the dictionary to save memory. _PyStaticType_Dealloc()

callers also test if tp_subclasses is NULL to check if a static type

has no subclass. */

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

PyInterpreterState *interp = _PyInterpreterState_GET();

managed_static_type_state *state = _PyStaticType_GetState(interp, self);

Py_CLEAR(state->tp_subclasses);

return;

}

Py_CLEAR(self->tp_subclasses);

}

static inline PyObject *

lookup_tp_subclasses(PyTypeObject *self)

{

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {

PyInterpreterState *interp = _PyInterpreterState_GET();

managed_static_type_state *state = _PyStaticType_GetState(interp, self);

assert(state != NULL);

return state->tp_subclasses;

}

return (PyObject *)self->tp_subclasses;

}

int

_PyType_HasSubclasses(PyTypeObject *self)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

if (self->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN

// XXX _PyStaticType_GetState() should never return NULL.

&& _PyStaticType_GetState(interp, self) == NULL)

{

return 0;

}

if (lookup_tp_subclasses(self) == NULL) {

return 0;

}

return 1;

}

PyObject*

_PyType_GetSubclasses(PyTypeObject *self)

{

PyObject *list = PyList_New(0);

if (list == NULL) {

return NULL;

}

PyObject *subclasses = lookup_tp_subclasses(self); // borrowed ref

if (subclasses == NULL) {

return list;

}

assert(PyDict_CheckExact(subclasses));

// The loop cannot modify tp_subclasses, there is no need

// to hold a strong reference (use a borrowed reference).

Py_ssize_t i = 0;

PyObject *ref; // borrowed ref

while (PyDict_Next(subclasses, &i, NULL, &ref)) {

PyTypeObject *subclass = type_from_ref(ref);

if (subclass == NULL) {

continue;

}

if (PyList_Append(list, _PyObject_CAST(subclass)) < 0) {

Py_DECREF(list);

Py_DECREF(subclass);

return NULL;

}

Py_DECREF(subclass);

}

return list;

}

/* end accessors for objects stored on PyTypeObject */

/*

* finds the beginning of the docstring's introspection signature.

* if present, returns a pointer pointing to the first '('.

* otherwise returns NULL.

*

* doesn't guarantee that the signature is valid, only that it

* has a valid prefix. (the signature must also pass skip_signature.)

*/

static const char *

find_signature(const char *name, const char *doc)

{

const char *dot;

size_t length;

if (!doc)

return NULL;

assert(name != NULL);

/* for dotted names like classes, only use the last component */

dot = strrchr(name, '.');

if (dot)

name = dot + 1;

length = strlen(name);

if (strncmp(doc, name, length))

return NULL;

doc += length;

if (*doc != '(')

return NULL;

return doc;

}

#define SIGNATURE_END_MARKER ")\n--\n\n"

#define SIGNATURE_END_MARKER_LENGTH 6

/*

* skips past the end of the docstring's introspection signature.

* (assumes doc starts with a valid signature prefix.)

*/

static const char *

skip_signature(const char *doc)

{

while (*doc) {

if ((*doc == *SIGNATURE_END_MARKER) &&

!strncmp(doc, SIGNATURE_END_MARKER, SIGNATURE_END_MARKER_LENGTH))

return doc + SIGNATURE_END_MARKER_LENGTH;

if ((*doc == '\n') && (doc[1] == '\n'))

return NULL;

doc++;

}

return NULL;

}

int

_PyType_CheckConsistency(PyTypeObject *type)

{

#define CHECK(expr) \

do { if (!(expr)) { _PyObject_ASSERT_FAILED_MSG((PyObject *)type, Py_STRINGIFY(expr)); } } while (0)

CHECK(!_PyObject_IsFreed((PyObject *)type));

if (!(type->tp_flags & Py_TPFLAGS_READY)) {

/* don't check static types before PyType_Ready() */

return 1;

}

CHECK(Py_REFCNT(type) >= 1);

CHECK(PyType_Check(type));

CHECK(!is_readying(type));

CHECK(lookup_tp_dict(type) != NULL);

if (type->tp_flags & Py_TPFLAGS_HAVE_GC) {

// bpo-44263: tp_traverse is required if Py_TPFLAGS_HAVE_GC is set.

// Note: tp_clear is optional.

CHECK(type->tp_traverse != NULL);

}

if (type->tp_flags & Py_TPFLAGS_DISALLOW_INSTANTIATION) {

CHECK(type->tp_new == NULL);

CHECK(PyDict_Contains(lookup_tp_dict(type), &_Py_ID(__new__)) == 0);

}

return 1;

#undef CHECK

}

static const char *

_PyType_DocWithoutSignature(const char *name, const char *internal_doc)

{

const char *doc = find_signature(name, internal_doc);

if (doc) {

doc = skip_signature(doc);

if (doc)

return doc;

}

return internal_doc;

}

PyObject *

_PyType_GetDocFromInternalDoc(const char *name, const char *internal_doc)

{

const char *doc = _PyType_DocWithoutSignature(name, internal_doc);

if (!doc || *doc == '\0') {

Py_RETURN_NONE;

}

return PyUnicode_FromString(doc);

}

static const char *

signature_from_flags(int flags)

{

switch (flags & ~METH_COEXIST) {

case METH_NOARGS:

return "($self, /)";

case METH_NOARGS|METH_CLASS:

return "($type, /)";

case METH_NOARGS|METH_STATIC:

return "()";

case METH_O:

return "($self, object, /)";

case METH_O|METH_CLASS:

return "($type, object, /)";

case METH_O|METH_STATIC:

return "(object, /)";

default:

return NULL;

}

}

PyObject *

_PyType_GetTextSignatureFromInternalDoc(const char *name, const char *internal_doc, int flags)

{

const char *start = find_signature(name, internal_doc);

const char *end;

if (start)

end = skip_signature(start);

else

end = NULL;

if (!end) {

start = signature_from_flags(flags);

if (start) {

return PyUnicode_FromString(start);

}

Py_RETURN_NONE;

}

/* back "end" up until it points just past the final ')' */

end -= SIGNATURE_END_MARKER_LENGTH - 1;

assert((end - start) >= 2); /* should be "()" at least */

assert(end[-1] == ')');

assert(end[0] == '\n');

return PyUnicode_FromStringAndSize(start, end - start);

}

static struct type_cache*

get_type_cache(void)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

return &interp->types.type_cache;

}

static void

type_cache_clear(struct type_cache *cache, PyObject *value)

{

for (Py_ssize_t i = 0; i < (1 << MCACHE_SIZE_EXP); i++) {

struct type_cache_entry *entry = &cache->hashtable[i];

#ifdef Py_GIL_DISABLED

_PySeqLock_LockWrite(&entry->sequence);

#endif

entry->version = 0;

Py_XSETREF(entry->name, _Py_XNewRef(value));

entry->value = NULL;

#ifdef Py_GIL_DISABLED

_PySeqLock_UnlockWrite(&entry->sequence);

#endif

}

}

void

_PyType_InitCache(PyInterpreterState *interp)

{

struct type_cache *cache = &interp->types.type_cache;

for (Py_ssize_t i = 0; i < (1 << MCACHE_SIZE_EXP); i++) {

struct type_cache_entry *entry = &cache->hashtable[i];

assert(entry->name == NULL);

entry->version = 0;

// Set to None so _PyType_LookupRef() can use Py_SETREF(),

// rather than using slower Py_XSETREF().

entry->name = Py_None;

entry->value = NULL;

}

}

static unsigned int

_PyType_ClearCache(PyInterpreterState *interp)

{

struct type_cache *cache = &interp->types.type_cache;

// Set to None, rather than NULL, so _PyType_LookupRef() can

// use Py_SETREF() rather than using slower Py_XSETREF().

type_cache_clear(cache, Py_None);

return NEXT_VERSION_TAG(interp) - 1;

}

unsigned int

PyType_ClearCache(void)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

return _PyType_ClearCache(interp);

}

void

_PyTypes_Fini(PyInterpreterState *interp)

{

struct type_cache *cache = &interp->types.type_cache;

type_cache_clear(cache, NULL);

// All the managed static types should have been finalized already.

assert(interp->types.for_extensions.num_initialized == 0);

for (size_t i = 0; i < _Py_MAX_MANAGED_STATIC_EXT_TYPES; i++) {

assert(interp->types.for_extensions.initialized[i].type == NULL);

}

assert(interp->types.builtins.num_initialized == 0);

for (size_t i = 0; i < _Py_MAX_MANAGED_STATIC_BUILTIN_TYPES; i++) {

assert(interp->types.builtins.initialized[i].type == NULL);

}

}

int

PyType_AddWatcher(PyType_WatchCallback callback)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

for (int i = 0; i < TYPE_MAX_WATCHERS; i++) {

if (!interp->type_watchers[i]) {

interp->type_watchers[i] = callback;

return i;

}

}

PyErr_SetString(PyExc_RuntimeError, "no more type watcher IDs available");

return -1;

}

static inline int

validate_watcher_id(PyInterpreterState *interp, int watcher_id)

{

if (watcher_id < 0 || watcher_id >= TYPE_MAX_WATCHERS) {

PyErr_Format(PyExc_ValueError, "Invalid type watcher ID %d", watcher_id);

return -1;

}

if (!interp->type_watchers[watcher_id]) {

PyErr_Format(PyExc_ValueError, "No type watcher set for ID %d", watcher_id);

return -1;

}

return 0;

}

int

PyType_ClearWatcher(int watcher_id)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

if (validate_watcher_id(interp, watcher_id) < 0) {

return -1;

}

interp->type_watchers[watcher_id] = NULL;

return 0;

}

static int assign_version_tag(PyInterpreterState *interp, PyTypeObject *type);

int

PyType_Watch(int watcher_id, PyObject* obj)

{

if (!PyType_Check(obj)) {

PyErr_SetString(PyExc_ValueError, "Cannot watch non-type");

return -1;

}

PyTypeObject *type = (PyTypeObject *)obj;

PyInterpreterState *interp = _PyInterpreterState_GET();

if (validate_watcher_id(interp, watcher_id) < 0) {

return -1;

}

// ensure we will get a callback on the next modification

BEGIN_TYPE_LOCK();

assign_version_tag(interp, type);

type->tp_watched |= (1 << watcher_id);

END_TYPE_LOCK();

return 0;

}

int

PyType_Unwatch(int watcher_id, PyObject* obj)

{

if (!PyType_Check(obj)) {

PyErr_SetString(PyExc_ValueError, "Cannot watch non-type");

return -1;

}

PyTypeObject *type = (PyTypeObject *)obj;

PyInterpreterState *interp = _PyInterpreterState_GET();

if (validate_watcher_id(interp, watcher_id)) {

return -1;

}

type->tp_watched &= ~(1 << watcher_id);

return 0;

}

static void

set_version_unlocked(PyTypeObject *tp, unsigned int version)

{

ASSERT_TYPE_LOCK_HELD();

assert(version == 0 || (tp->tp_versions_used != _Py_ATTR_CACHE_UNUSED));

#ifndef Py_GIL_DISABLED

if (version) {

tp->tp_versions_used++;

}

#else

if (version) {

_Py_atomic_add_uint16(&tp->tp_versions_used, 1);

}

#endif

FT_ATOMIC_STORE_UINT_RELAXED(tp->tp_version_tag, version);

}

static void

type_modified_unlocked(PyTypeObject *type)

{

/* Invalidate any cached data for the specified type and all

subclasses. This function is called after the base

classes, mro, or attributes of the type are altered.

Invariants:

- before tp_version_tag can be set on a type,

it must first be set on all super types.

This function clears the tp_version_tag of a

type (so it must first clear it on all subclasses). The

tp_version_tag value is meaningless when equal to zero.

We don't assign new version tags eagerly, but only as

needed.

*/