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pythongh-116621: Set manual critical section for list.extend (pythong…
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…h-116657)
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@corona10 @vstinner
corona10 authored and vstinner committed Mar 20, 2024
1 parent 474a672 commit a01cbca
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Showing 2 changed files with 97 additions and 64 deletions.
23 changes: 4 additions & 19 deletions Objects/clinic/listobject.c.h
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138 changes: 93 additions & 45 deletions Objects/listobject.c
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Expand Up @@ -10,6 +10,7 @@
#include "pycore_modsupport.h" // _PyArg_NoKwnames()
#include "pycore_object.h" // _PyObject_GC_TRACK(), _PyDebugAllocatorStats()
#include "pycore_tuple.h" // _PyTuple_FromArray()
#include "pycore_setobject.h" // _PySet_NextEntry()
#include <stddef.h>

/*[clinic input]
Expand Down Expand Up @@ -994,35 +995,36 @@ PyList_SetSlice(PyObject *a, Py_ssize_t ilow, Py_ssize_t ihigh, PyObject *v)
return list_ass_slice((PyListObject *)a, ilow, ihigh, v);
}

static PyObject *
static int
list_inplace_repeat_lock_held(PyListObject *self, Py_ssize_t n)
{
Py_ssize_t input_size = PyList_GET_SIZE(self);
if (input_size == 0 || n == 1) {
return Py_NewRef(self);
return 0;
}

if (n < 1) {
list_clear(self);
return Py_NewRef(self);
return 0;
}

if (input_size > PY_SSIZE_T_MAX / n) {
return PyErr_NoMemory();
PyErr_NoMemory();
return -1;
}
Py_ssize_t output_size = input_size * n;

if (list_resize(self, output_size) < 0)
return NULL;
if (list_resize(self, output_size) < 0) {
return -1;
}

PyObject **items = self->ob_item;
for (Py_ssize_t j = 0; j < input_size; j++) {
_Py_RefcntAdd(items[j], n-1);
}
_Py_memory_repeat((char *)items, sizeof(PyObject *)*output_size,
sizeof(PyObject *)*input_size);

return Py_NewRef(self);
return 0;
}

static PyObject *
Expand All @@ -1031,7 +1033,12 @@ list_inplace_repeat(PyObject *_self, Py_ssize_t n)
PyObject *ret;
PyListObject *self = (PyListObject *) _self;
Py_BEGIN_CRITICAL_SECTION(self);
ret = list_inplace_repeat_lock_held(self, n);
if (list_inplace_repeat_lock_held(self, n) < 0) {
ret = NULL;
}
else {
ret = Py_NewRef(self);
}
Py_END_CRITICAL_SECTION();
return ret;
}
Expand Down Expand Up @@ -1179,7 +1186,7 @@ list_extend_fast(PyListObject *self, PyObject *iterable)
}

static int
list_extend_iter(PyListObject *self, PyObject *iterable)
list_extend_iter_lock_held(PyListObject *self, PyObject *iterable)
{
PyObject *it = PyObject_GetIter(iterable);
if (it == NULL) {
Expand Down Expand Up @@ -1253,45 +1260,78 @@ list_extend_iter(PyListObject *self, PyObject *iterable)
return -1;
}


static int
list_extend(PyListObject *self, PyObject *iterable)
list_extend_lock_held(PyListObject *self, PyObject *iterable)
{
// Special cases:
// 1) lists and tuples which can use PySequence_Fast ops
// 2) extending self to self requires making a copy first
if (PyList_CheckExact(iterable)
|| PyTuple_CheckExact(iterable)
|| (PyObject *)self == iterable)
{
iterable = PySequence_Fast(iterable, "argument must be iterable");
if (!iterable) {
return -1;
}

int res = list_extend_fast(self, iterable);
Py_DECREF(iterable);
return res;
}
else {
return list_extend_iter(self, iterable);
PyObject *seq = PySequence_Fast(iterable, "argument must be iterable");
if (!seq) {
return -1;
}
}

int res = list_extend_fast(self, seq);
Py_DECREF(seq);
return res;
}

PyObject *
_PyList_Extend(PyListObject *self, PyObject *iterable)
static int
list_extend_set(PyListObject *self, PySetObject *other)
{
if (list_extend(self, iterable) < 0) {
return NULL;
Py_ssize_t m = Py_SIZE(self);
Py_ssize_t n = PySet_GET_SIZE(other);
if (list_resize(self, m + n) < 0) {
return -1;
}
Py_RETURN_NONE;
/* populate the end of self with iterable's items */
Py_ssize_t setpos = 0;
Py_hash_t hash;
PyObject *key;
PyObject **dest = self->ob_item + m;
while (_PySet_NextEntry((PyObject *)other, &setpos, &key, &hash)) {
Py_INCREF(key);
*dest = key;
dest++;
}
Py_SET_SIZE(self, m + n);
return 0;
}

static int
_list_extend(PyListObject *self, PyObject *iterable)
{
// Special case:
// lists and tuples which can use PySequence_Fast ops
// TODO(@corona10): Add more special cases for other types.
int res = -1;
if ((PyObject *)self == iterable) {
Py_BEGIN_CRITICAL_SECTION(self);
res = list_inplace_repeat_lock_held(self, 2);
Py_END_CRITICAL_SECTION();
}
else if (PyList_CheckExact(iterable)) {
Py_BEGIN_CRITICAL_SECTION2(self, iterable);
res = list_extend_lock_held(self, iterable);
Py_END_CRITICAL_SECTION2();
}
else if (PyTuple_CheckExact(iterable)) {
Py_BEGIN_CRITICAL_SECTION(self);
res = list_extend_lock_held(self, iterable);
Py_END_CRITICAL_SECTION();
}
else if (PyAnySet_CheckExact(iterable)) {
Py_BEGIN_CRITICAL_SECTION2(self, iterable);
res = list_extend_set(self, (PySetObject *)iterable);
Py_END_CRITICAL_SECTION2();
}
else {
Py_BEGIN_CRITICAL_SECTION(self);
res = list_extend_iter_lock_held(self, iterable);
Py_END_CRITICAL_SECTION();
}
return res;
}

/*[clinic input]
@critical_section self iterable
list.extend as py_list_extend
list.extend as list_extend
iterable: object
/
Expand All @@ -1300,12 +1340,20 @@ Extend list by appending elements from the iterable.
[clinic start generated code]*/

static PyObject *
py_list_extend_impl(PyListObject *self, PyObject *iterable)
/*[clinic end generated code: output=a2f115ceace2c845 input=1d42175414e1a5f3]*/
list_extend(PyListObject *self, PyObject *iterable)
/*[clinic end generated code: output=630fb3bca0c8e789 input=979da7597a515791]*/
{
return _PyList_Extend(self, iterable);
if (_list_extend(self, iterable) < 0) {
return NULL;
}
Py_RETURN_NONE;
}

PyObject *
_PyList_Extend(PyListObject *self, PyObject *iterable)
{
return list_extend(self, iterable);
}

int
PyList_Extend(PyObject *self, PyObject *iterable)
Expand All @@ -1314,7 +1362,7 @@ PyList_Extend(PyObject *self, PyObject *iterable)
PyErr_BadInternalCall();
return -1;
}
return list_extend((PyListObject*)self, iterable);
return _list_extend((PyListObject*)self, iterable);
}


Expand All @@ -1334,7 +1382,7 @@ static PyObject *
list_inplace_concat(PyObject *_self, PyObject *other)
{
PyListObject *self = (PyListObject *)_self;
if (list_extend(self, other) < 0) {
if (_list_extend(self, other) < 0) {
return NULL;
}
return Py_NewRef(self);
Expand Down Expand Up @@ -3168,7 +3216,7 @@ list___init___impl(PyListObject *self, PyObject *iterable)
list_clear(self);
}
if (iterable != NULL) {
if (list_extend(self, iterable) < 0) {
if (_list_extend(self, iterable) < 0) {
return -1;
}
}
Expand Down Expand Up @@ -3229,7 +3277,7 @@ static PyMethodDef list_methods[] = {
LIST_COPY_METHODDEF
LIST_APPEND_METHODDEF
LIST_INSERT_METHODDEF
PY_LIST_EXTEND_METHODDEF
LIST_EXTEND_METHODDEF
LIST_POP_METHODDEF
LIST_REMOVE_METHODDEF
LIST_INDEX_METHODDEF
Expand Down

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