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gh-115999: Stop the world when invalidating function versions #124997

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merged 1 commit into from
Oct 8, 2024
Merged

gh-115999: Stop the world when invalidating function versions #124997

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10 changes: 10 additions & 0 deletions Include/internal/pycore_function.h
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,10 @@ extern PyObject* _PyFunction_Vectorcall(

#define FUNC_MAX_WATCHERS 8

#define FUNC_VERSION_UNSET 0
#define FUNC_VERSION_CLEARED 1
#define FUNC_VERSION_FIRST_VALID 2

#define FUNC_VERSION_CACHE_SIZE (1<<12) /* Must be a power of 2 */

struct _func_version_cache_item {
Expand All @@ -41,6 +45,12 @@ struct _py_func_state {

extern PyFunctionObject* _PyFunction_FromConstructor(PyFrameConstructor *constr);

static inline int
_PyFunction_IsVersionValid(uint32_t version)
{
return version >= FUNC_VERSION_FIRST_VALID;
}

extern uint32_t _PyFunction_GetVersionForCurrentState(PyFunctionObject *func);
PyAPI_FUNC(void) _PyFunction_SetVersion(PyFunctionObject *func, uint32_t version);
void _PyFunction_ClearCodeByVersion(uint32_t version);
Expand Down
3 changes: 2 additions & 1 deletion Include/internal/pycore_runtime_init.h
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ extern "C" {
#include "pycore_ceval_state.h" // _PyEval_RUNTIME_PERF_INIT
#include "pycore_faulthandler.h" // _faulthandler_runtime_state_INIT
#include "pycore_floatobject.h" // _py_float_format_unknown
#include "pycore_function.h"
#include "pycore_object.h" // _PyObject_HEAD_INIT
#include "pycore_obmalloc_init.h" // _obmalloc_global_state_INIT
#include "pycore_parser.h" // _parser_runtime_state_INIT
Expand Down Expand Up @@ -243,7 +244,7 @@ extern PyTypeObject _PyExc_MemoryError;
.dict_state = _dict_state_INIT, \
.mem_free_queue = _Py_mem_free_queue_INIT(INTERP.mem_free_queue), \
.func_state = { \
.next_version = 1, \
.next_version = FUNC_VERSION_FIRST_VALID, \
}, \
.types = { \
.next_version_tag = _Py_TYPE_BASE_VERSION_TAG, \
Expand Down
89 changes: 56 additions & 33 deletions Objects/funcobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -128,7 +128,7 @@ _PyFunction_FromConstructor(PyFrameConstructor *constr)
op->func_annotate = NULL;
op->func_typeparams = NULL;
op->vectorcall = _PyFunction_Vectorcall;
op->func_version = 0;
op->func_version = FUNC_VERSION_UNSET;
// NOTE: functions created via FrameConstructor do not use deferred
// reference counting because they are typically not part of cycles
// nor accessed by multiple threads.
Expand Down Expand Up @@ -207,7 +207,7 @@ PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname
op->func_annotate = NULL;
op->func_typeparams = NULL;
op->vectorcall = _PyFunction_Vectorcall;
op->func_version = 0;
op->func_version = FUNC_VERSION_UNSET;
if ((code_obj->co_flags & CO_NESTED) == 0) {
// Use deferred reference counting for top-level functions, but not
// nested functions because they are more likely to capture variables,
Expand Down Expand Up @@ -287,41 +287,67 @@ functions is running.

*/

static inline struct _func_version_cache_item *
get_cache_item(PyInterpreterState *interp, uint32_t version)
{
return interp->func_state.func_version_cache +
(version % FUNC_VERSION_CACHE_SIZE);
}

void
_PyFunction_SetVersion(PyFunctionObject *func, uint32_t version)
{
assert(func->func_version == FUNC_VERSION_UNSET);
assert(version >= FUNC_VERSION_FIRST_VALID);
// This should only be called from MAKE_FUNCTION. No code is specialized
// based on the version, so we do not need to stop the world to set it.
func->func_version = version;
#ifndef Py_GIL_DISABLED
PyInterpreterState *interp = _PyInterpreterState_GET();
if (func->func_version != 0) {
struct _func_version_cache_item *slot =
interp->func_state.func_version_cache
+ (func->func_version % FUNC_VERSION_CACHE_SIZE);
if (slot->func == func) {
slot->func = NULL;
// Leave slot->code alone, there may be use for it.
}
}
struct _func_version_cache_item *slot = get_cache_item(interp, version);
slot->func = func;
slot->code = func->func_code;
#endif
func->func_version = version;
}

static void
func_clear_version(PyInterpreterState *interp, PyFunctionObject *func)
{
if (func->func_version < FUNC_VERSION_FIRST_VALID) {
// Version was never set or has already been cleared.
return;
}
#ifndef Py_GIL_DISABLED
if (version != 0) {
struct _func_version_cache_item *slot =
interp->func_state.func_version_cache
+ (version % FUNC_VERSION_CACHE_SIZE);
slot->func = func;
slot->code = func->func_code;
struct _func_version_cache_item *slot =
get_cache_item(interp, func->func_version);
if (slot->func == func) {
slot->func = NULL;
// Leave slot->code alone, there may be use for it.
}
#endif
func->func_version = FUNC_VERSION_CLEARED;
}

// Called when any of the critical function attributes are changed
static void
_PyFunction_ClearVersion(PyFunctionObject *func)
{
if (func->func_version < FUNC_VERSION_FIRST_VALID) {
// Version was never set or has already been cleared.
return;
}
PyInterpreterState *interp = _PyInterpreterState_GET();
_PyEval_StopTheWorld(interp);
func_clear_version(interp, func);
_PyEval_StartTheWorld(interp);
}

void
_PyFunction_ClearCodeByVersion(uint32_t version)
{
#ifndef Py_GIL_DISABLED
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _func_version_cache_item *slot =
interp->func_state.func_version_cache
+ (version % FUNC_VERSION_CACHE_SIZE);
struct _func_version_cache_item *slot = get_cache_item(interp, version);
if (slot->code) {
assert(PyCode_Check(slot->code));
PyCodeObject *code = (PyCodeObject *)slot->code;
Expand All @@ -340,9 +366,7 @@ _PyFunction_LookupByVersion(uint32_t version, PyObject **p_code)
return NULL;
#else
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _func_version_cache_item *slot =
interp->func_state.func_version_cache
+ (version % FUNC_VERSION_CACHE_SIZE);
struct _func_version_cache_item *slot = get_cache_item(interp, version);
if (slot->code) {
assert(PyCode_Check(slot->code));
PyCodeObject *code = (PyCodeObject *)slot->code;
Expand Down Expand Up @@ -431,7 +455,7 @@ PyFunction_SetDefaults(PyObject *op, PyObject *defaults)
}
handle_func_event(PyFunction_EVENT_MODIFY_DEFAULTS,
(PyFunctionObject *) op, defaults);
_PyFunction_SetVersion((PyFunctionObject *)op, 0);
_PyFunction_ClearVersion((PyFunctionObject *)op);
Py_XSETREF(((PyFunctionObject *)op)->func_defaults, defaults);
return 0;
}
Expand All @@ -440,7 +464,7 @@ void
PyFunction_SetVectorcall(PyFunctionObject *func, vectorcallfunc vectorcall)
{
assert(func != NULL);
_PyFunction_SetVersion(func, 0);
_PyFunction_ClearVersion(func);
func->vectorcall = vectorcall;
}

Expand Down Expand Up @@ -473,7 +497,7 @@ PyFunction_SetKwDefaults(PyObject *op, PyObject *defaults)
}
handle_func_event(PyFunction_EVENT_MODIFY_KWDEFAULTS,
(PyFunctionObject *) op, defaults);
_PyFunction_SetVersion((PyFunctionObject *)op, 0);
_PyFunction_ClearVersion((PyFunctionObject *)op);
Py_XSETREF(((PyFunctionObject *)op)->func_kwdefaults, defaults);
return 0;
}
Expand Down Expand Up @@ -506,7 +530,7 @@ PyFunction_SetClosure(PyObject *op, PyObject *closure)
Py_TYPE(closure)->tp_name);
return -1;
}
_PyFunction_SetVersion((PyFunctionObject *)op, 0);
_PyFunction_ClearVersion((PyFunctionObject *)op);
Py_XSETREF(((PyFunctionObject *)op)->func_closure, closure);
return 0;
}
Expand Down Expand Up @@ -658,7 +682,7 @@ func_set_code(PyObject *self, PyObject *value, void *Py_UNUSED(ignored))
}

handle_func_event(PyFunction_EVENT_MODIFY_CODE, op, value);
_PyFunction_SetVersion(op, 0);
_PyFunction_ClearVersion(op);
Py_XSETREF(op->func_code, Py_NewRef(value));
return 0;
}
Expand Down Expand Up @@ -744,7 +768,7 @@ func_set_defaults(PyObject *self, PyObject *value, void *Py_UNUSED(ignored))
}

handle_func_event(PyFunction_EVENT_MODIFY_DEFAULTS, op, value);
_PyFunction_SetVersion(op, 0);
_PyFunction_ClearVersion(op);
Py_XSETREF(op->func_defaults, Py_XNewRef(value));
return 0;
}
Expand Down Expand Up @@ -787,7 +811,7 @@ func_set_kwdefaults(PyObject *self, PyObject *value, void *Py_UNUSED(ignored))
}

handle_func_event(PyFunction_EVENT_MODIFY_KWDEFAULTS, op, value);
_PyFunction_SetVersion(op, 0);
_PyFunction_ClearVersion(op);
Py_XSETREF(op->func_kwdefaults, Py_XNewRef(value));
return 0;
}
Expand Down Expand Up @@ -1030,7 +1054,7 @@ static int
func_clear(PyObject *self)
{
PyFunctionObject *op = _PyFunction_CAST(self);
_PyFunction_SetVersion(op, 0);
func_clear_version(_PyInterpreterState_GET(), op);
Py_CLEAR(op->func_globals);
Py_CLEAR(op->func_builtins);
Py_CLEAR(op->func_module);
Expand Down Expand Up @@ -1068,7 +1092,6 @@ func_dealloc(PyObject *self)
if (op->func_weakreflist != NULL) {
PyObject_ClearWeakRefs((PyObject *) op);
}
_PyFunction_SetVersion(op, 0);
(void)func_clear((PyObject*)op);
// These aren't cleared by func_clear().
Py_DECREF(op->func_code);
Expand Down
8 changes: 4 additions & 4 deletions Python/specialize.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1599,7 +1599,7 @@ function_get_version(PyObject *o, int opcode)
assert(Py_IS_TYPE(o, &PyFunction_Type));
PyFunctionObject *func = (PyFunctionObject *)o;
uint32_t version = _PyFunction_GetVersionForCurrentState(func);
if (version == 0) {
if (!_PyFunction_IsVersionValid(version)) {
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_OUT_OF_VERSIONS);
return 0;
}
Expand Down Expand Up @@ -1692,7 +1692,7 @@ _Py_Specialize_BinarySubscr(
goto fail;
}
uint32_t version = _PyFunction_GetVersionForCurrentState(func);
if (version == 0) {
if (!_PyFunction_IsVersionValid(version)) {
SPECIALIZATION_FAIL(BINARY_SUBSCR, SPEC_FAIL_OUT_OF_VERSIONS);
goto fail;
}
Expand Down Expand Up @@ -1977,7 +1977,7 @@ specialize_py_call(PyFunctionObject *func, _Py_CODEUNIT *instr, int nargs,
argcount = code->co_argcount;
}
int version = _PyFunction_GetVersionForCurrentState(func);
if (version == 0) {
if (!_PyFunction_IsVersionValid(version)) {
SPECIALIZATION_FAIL(CALL, SPEC_FAIL_OUT_OF_VERSIONS);
return -1;
}
Expand Down Expand Up @@ -2009,7 +2009,7 @@ specialize_py_call_kw(PyFunctionObject *func, _Py_CODEUNIT *instr, int nargs,
return -1;
}
int version = _PyFunction_GetVersionForCurrentState(func);
if (version == 0) {
if (!_PyFunction_IsVersionValid(version)) {
SPECIALIZATION_FAIL(CALL, SPEC_FAIL_OUT_OF_VERSIONS);
return -1;
}
Expand Down
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