bpo-32030: Rework memory allocators (#4625)

* Fix _PyMem_SetupAllocators("debug"): always restore allocators to
  the defaults, rather than only caling _PyMem_SetupDebugHooks().
* Add _PyMem_SetDefaultAllocator() helper to set the "default"
  allocator.
* Add _PyMem_GetAllocatorsName(): get the name of the allocators
* main() now uses debug hooks on memory allocators if Py_DEBUG is
  defined, rather than calling directly malloc()
* Document default memory allocators in C API documentation
* _Py_InitializeCore() now fails with a fatal user error if
  PYTHONMALLOC value is an unknown memory allocator, instead of
  failing with a fatal internal error.
* Add new tests on the PYTHONMALLOC environment variable
* Add support.with_pymalloc()
* Add the _testcapi.WITH_PYMALLOC constant and expose it as
   support.with_pymalloc().
* sysconfig.get_config_var('WITH_PYMALLOC') doesn't work on Windows, so
   replace it with support.with_pymalloc().
* pythoninfo: add _testcapi collector for pymem

1 files changed, 19 insertions, 0 deletions

diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 7a5771921b..4bb3e82d1d 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -4104,6 +4104,19 @@ pymem_malloc_without_gil(PyObject *self, PyObject *args)
     Py_RETURN_NONE;
 }
 
+
+static PyObject*
+test_pymem_getallocatorsname(PyObject *self, PyObject *args)
+{
+    const char *name = _PyMem_GetAllocatorsName();
+    if (name == NULL) {
+        PyErr_SetString(PyExc_RuntimeError, "cannot get allocators name");
+        return NULL;
+    }
+    return PyUnicode_FromString(name);
+}
+
+
 static PyObject*
 pyobject_malloc_without_gil(PyObject *self, PyObject *args)
 {
@@ -4624,6 +4637,7 @@ static PyMethodDef TestMethods[] = {
     {"pymem_buffer_overflow", pymem_buffer_overflow, METH_NOARGS},
     {"pymem_api_misuse", pymem_api_misuse, METH_NOARGS},
     {"pymem_malloc_without_gil", pymem_malloc_without_gil, METH_NOARGS},
+    {"pymem_getallocatorsname", test_pymem_getallocatorsname, METH_NOARGS},
     {"pyobject_malloc_without_gil", pyobject_malloc_without_gil, METH_NOARGS},
     {"tracemalloc_track", tracemalloc_track, METH_VARARGS},
     {"tracemalloc_untrack", tracemalloc_untrack, METH_VARARGS},
@@ -5115,6 +5129,11 @@ PyInit__testcapi(void)
     PyModule_AddObject(m, "instancemethod", (PyObject *)&PyInstanceMethod_Type);
 
     PyModule_AddIntConstant(m, "the_number_three", 3);
+#ifdef WITH_PYMALLOC
+    PyModule_AddObject(m, "WITH_PYMALLOC", Py_True);
+#else
+    PyModule_AddObject(m, "WITH_PYMALLOC", Py_False);
+#endif
 
     TestError = PyErr_NewException("_testcapi.error", NULL, NULL);
     Py_INCREF(TestError);