Issue #2534: speed up isinstance() and issubclass() by 50-70%, so as to
match Python 2.5 speed despite the __instancecheck__ / __subclasscheck__
mechanism. In the process, fix a bug where isinstance() and issubclass(),
when given a tuple of classes as second argument, were looking up
__instancecheck__ / __subclasscheck__ on the tuple rather than on each
type object.
Reviewed by Benjamin Peterson and Raymond Hettinger.
diff --git a/Objects/abstract.c b/Objects/abstract.c
index 8f7083d..ac61011 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -2474,39 +2474,38 @@
static int
abstract_issubclass(PyObject *derived, PyObject *cls)
{
- PyObject *bases;
+ PyObject *bases = NULL;
Py_ssize_t i, n;
int r = 0;
-
- if (derived == cls)
- return 1;
-
- if (PyTuple_Check(cls)) {
- /* Not a general sequence -- that opens up the road to
- recursion and stack overflow. */
- n = PyTuple_GET_SIZE(cls);
- for (i = 0; i < n; i++) {
- if (derived == PyTuple_GET_ITEM(cls, i))
- return 1;
+ while (1) {
+ if (derived == cls)
+ return 1;
+ bases = abstract_get_bases(derived);
+ if (bases == NULL) {
+ if (PyErr_Occurred())
+ return -1;
+ return 0;
}
+ n = PyTuple_GET_SIZE(bases);
+ if (n == 0) {
+ Py_DECREF(bases);
+ return 0;
+ }
+ /* Avoid recursivity in the single inheritance case */
+ if (n == 1) {
+ derived = PyTuple_GET_ITEM(bases, 0);
+ Py_DECREF(bases);
+ continue;
+ }
+ for (i = 0; i < n; i++) {
+ r = abstract_issubclass(PyTuple_GET_ITEM(bases, i), cls);
+ if (r != 0)
+ break;
+ }
+ Py_DECREF(bases);
+ return r;
}
- bases = abstract_get_bases(derived);
- if (bases == NULL) {
- if (PyErr_Occurred())
- return -1;
- return 0;
- }
- n = PyTuple_GET_SIZE(bases);
- for (i = 0; i < n; i++) {
- r = abstract_issubclass(PyTuple_GET_ITEM(bases, i), cls);
- if (r != 0)
- break;
- }
-
- Py_DECREF(bases);
-
- return r;
}
static int
@@ -2524,7 +2523,7 @@
}
static int
-recursive_isinstance(PyObject *inst, PyObject *cls, int recursion_depth)
+recursive_isinstance(PyObject *inst, PyObject *cls)
{
PyObject *icls;
static PyObject *__class__ = NULL;
@@ -2553,25 +2552,6 @@
}
}
}
- else if (PyTuple_Check(cls)) {
- Py_ssize_t i, n;
-
- if (!recursion_depth) {
- PyErr_SetString(PyExc_RuntimeError,
- "nest level of tuple too deep");
- return -1;
- }
-
- n = PyTuple_GET_SIZE(cls);
- for (i = 0; i < n; i++) {
- retval = recursive_isinstance(
- inst,
- PyTuple_GET_ITEM(cls, i),
- recursion_depth-1);
- if (retval != 0)
- break;
- }
- }
else {
if (!check_class(cls,
"isinstance() arg 2 must be a class, type,"
@@ -2601,6 +2581,24 @@
if (Py_TYPE(inst) == (PyTypeObject *)cls)
return 1;
+ if (PyTuple_Check(cls)) {
+ Py_ssize_t i;
+ Py_ssize_t n;
+ int r = 0;
+
+ if (Py_EnterRecursiveCall(" in __instancecheck__"))
+ return -1;
+ n = PyTuple_GET_SIZE(cls);
+ for (i = 0; i < n; ++i) {
+ PyObject *item = PyTuple_GET_ITEM(cls, i);
+ r = PyObject_IsInstance(inst, item);
+ if (r != 0)
+ /* either found it, or got an error */
+ break;
+ }
+ Py_LeaveRecursiveCall();
+ return r;
+ }
if (name == NULL) {
name = PyUnicode_InternFromString("__instancecheck__");
if (name == NULL)
@@ -2625,51 +2623,25 @@
}
return ok;
}
- return recursive_isinstance(inst, cls, Py_GetRecursionLimit());
+ return recursive_isinstance(inst, cls);
}
static int
-recursive_issubclass(PyObject *derived, PyObject *cls, int recursion_depth)
+recursive_issubclass(PyObject *derived, PyObject *cls)
{
- int retval;
-
- {
- if (!check_class(derived,
- "issubclass() arg 1 must be a class"))
- return -1;
-
- if (PyTuple_Check(cls)) {
- Py_ssize_t i;
- Py_ssize_t n = PyTuple_GET_SIZE(cls);
-
- if (!recursion_depth) {
- PyErr_SetString(PyExc_RuntimeError,
- "nest level of tuple too deep");
- return -1;
- }
- for (i = 0; i < n; ++i) {
- retval = recursive_issubclass(
- derived,
- PyTuple_GET_ITEM(cls, i),
- recursion_depth-1);
- if (retval != 0) {
- /* either found it, or got an error */
- return retval;
- }
- }
- return 0;
- }
- else {
- if (!check_class(cls,
- "issubclass() arg 2 must be a class"
- " or tuple of classes"))
- return -1;
- }
-
- retval = abstract_issubclass(derived, cls);
+ if (PyType_Check(cls) && PyType_Check(derived)) {
+ /* Fast path (non-recursive) */
+ return PyType_IsSubtype((PyTypeObject *)derived, (PyTypeObject *)cls);
}
+ if (!check_class(derived,
+ "issubclass() arg 1 must be a class"))
+ return -1;
+ if (!check_class(cls,
+ "issubclass() arg 2 must be a class"
+ " or tuple of classes"))
+ return -1;
- return retval;
+ return abstract_issubclass(derived, cls);
}
int
@@ -2678,20 +2650,40 @@
static PyObject *name = NULL;
PyObject *t, *v, *tb;
PyObject *checker;
- PyErr_Fetch(&t, &v, &tb);
+ if (PyTuple_Check(cls)) {
+ Py_ssize_t i;
+ Py_ssize_t n;
+ int r = 0;
+
+ if (Py_EnterRecursiveCall(" in __subclasscheck__"))
+ return -1;
+ n = PyTuple_GET_SIZE(cls);
+ for (i = 0; i < n; ++i) {
+ PyObject *item = PyTuple_GET_ITEM(cls, i);
+ r = PyObject_IsSubclass(derived, item);
+ if (r != 0)
+ /* either found it, or got an error */
+ break;
+ }
+ Py_LeaveRecursiveCall();
+ return r;
+ }
if (name == NULL) {
name = PyUnicode_InternFromString("__subclasscheck__");
if (name == NULL)
return -1;
}
+ PyErr_Fetch(&t, &v, &tb);
checker = PyObject_GetAttr(cls, name);
PyErr_Restore(t, v, tb);
if (checker != NULL) {
PyObject *res;
int ok = -1;
- if (Py_EnterRecursiveCall(" in __subclasscheck__"))
+ if (Py_EnterRecursiveCall(" in __subclasscheck__")) {
+ Py_DECREF(checker);
return ok;
+ }
res = PyObject_CallFunctionObjArgs(checker, derived, NULL);
Py_LeaveRecursiveCall();
Py_DECREF(checker);
@@ -2701,7 +2693,19 @@
}
return ok;
}
- return recursive_issubclass(derived, cls, Py_GetRecursionLimit());
+ return recursive_issubclass(derived, cls);
+}
+
+int
+_PyObject_RealIsInstance(PyObject *inst, PyObject *cls)
+{
+ return recursive_isinstance(inst, cls);
+}
+
+int
+_PyObject_RealIsSubclass(PyObject *derived, PyObject *cls)
+{
+ return recursive_issubclass(derived, cls);
}