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bpo-46541: Replace core use of _Py_IDENTIFIER() with statically initialized global objects. (gh-30928)

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We're no longer using _Py_IDENTIFIER() (or _Py_static_string()) in any core CPython code.  It is still used in a number of non-builtin stdlib modules.

The replacement is: PyUnicodeObject (not pointer) fields under _PyRuntimeState, statically initialized as part of _PyRuntime.  A new _Py_GET_GLOBAL_IDENTIFIER() macro facilitates lookup of the fields (along with _Py_GET_GLOBAL_STRING() for non-identifier strings).

https://bugs.python.org/issue46541#msg411799 explains the rationale for this change.

The core of the change is in:

* (new) Include/internal/pycore_global_strings.h - the declarations for the global strings, along with the macros
* Include/internal/pycore_runtime_init.h - added the static initializers for the global strings
* Include/internal/pycore_global_objects.h - where the struct in pycore_global_strings.h is hooked into _PyRuntimeState
* Tools/scripts/generate_global_objects.py - added generation of the global string declarations and static initializers

I've also added a --check flag to generate_global_objects.py (along with make check-global-objects) to check for unused global strings.  That check is added to the PR CI config.

The remainder of this change updates the core code to use _Py_GET_GLOBAL_IDENTIFIER() instead of _Py_IDENTIFIER() and the related _Py*Id functions (likewise for _Py_GET_GLOBAL_STRING() instead of _Py_static_string()).  This includes adding a few functions where there wasn't already an alternative to _Py*Id(), replacing the _Py_Identifier * parameter with PyObject *.

The following are not changed (yet):

* stop using _Py_IDENTIFIER() in the stdlib modules
* (maybe) get rid of _Py_IDENTIFIER(), etc. entirely -- this may not be doable as at least one package on PyPI using this (private) API
* (maybe) intern the strings during runtime init

https://bugs.python.org/issue46541
This commit is contained in:
Eric Snow 2022-02-08 13:39:07 -07:00 • committed by GitHub
parent c018d3037b
commit 81c72044a1
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GPG key ID: 4AEE18F83AFDEB23
108 changed files with 2282 additions and 1573 deletions
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27
Modules/_threadmodule.c
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@ -17,11 +17,6 @@
// ThreadError is just an alias to PyExc_RuntimeError
#define ThreadError PyExc_RuntimeError
_Py_IDENTIFIER(__dict__);
_Py_IDENTIFIER(stderr);
_Py_IDENTIFIER(flush);
// Forward declarations
static struct PyModuleDef thread_module;
@ -938,12 +933,7 @@ local_setattro(localobject *self, PyObject *name, PyObject *v)
return -1;
}
PyObject *str_dict = _PyUnicode_FromId(&PyId___dict__); // borrowed ref
if (str_dict == NULL) {
return -1;
}
int r = PyObject_RichCompareBool(name, str_dict, Py_EQ);
int r = PyObject_RichCompareBool(name, &_Py_ID(__dict__), Py_EQ);
if (r == -1) {
return -1;
}
@ -994,12 +984,7 @@ local_getattro(localobject *self, PyObject *name)
if (ldict == NULL)
return NULL;
PyObject *str_dict = _PyUnicode_FromId(&PyId___dict__); // borrowed ref
if (str_dict == NULL) {
return NULL;
}
int r = PyObject_RichCompareBool(name, str_dict, Py_EQ);
int r = PyObject_RichCompareBool(name, &_Py_ID(__dict__), Py_EQ);
if (r == 1) {
return Py_NewRef(ldict);
}
@ -1413,7 +1398,6 @@ static int
thread_excepthook_file(PyObject *file, PyObject *exc_type, PyObject *exc_value,
PyObject *exc_traceback, PyObject *thread)
{
_Py_IDENTIFIER(name);
/* print(f"Exception in thread {thread.name}:", file=file) */
if (PyFile_WriteString("Exception in thread ", file) < 0) {
return -1;
@ -1421,7 +1405,7 @@ thread_excepthook_file(PyObject *file, PyObject *exc_type, PyObject *exc_value,
PyObject *name = NULL;
if (thread != Py_None) {
if (_PyObject_LookupAttrId(thread, &PyId_name, &name) < 0) {
if (_PyObject_LookupAttr(thread, &_Py_ID(name), &name) < 0) {
return -1;
}
}
@ -1459,7 +1443,7 @@ thread_excepthook_file(PyObject *file, PyObject *exc_type, PyObject *exc_value,
_PyErr_Display(file, exc_type, exc_value, exc_traceback);
/* Call file.flush() */
PyObject *res = _PyObject_CallMethodIdNoArgs(file, &PyId_flush);
PyObject *res = PyObject_CallMethodNoArgs(file, &_Py_ID(flush));
if (!res) {
return -1;
}
@ -1514,7 +1498,8 @@ thread_excepthook(PyObject *module, PyObject *args)
PyObject *exc_tb = PyStructSequence_GET_ITEM(args, 2);
PyObject *thread = PyStructSequence_GET_ITEM(args, 3);
PyObject *file = _PySys_GetObjectId(&PyId_stderr);
PyThreadState *tstate = _PyThreadState_GET();
PyObject *file = _PySys_GetAttr(tstate, &_Py_ID(stderr));
if (file == NULL || file == Py_None) {
if (thread == Py_None) {
/* do nothing if sys.stderr is None and thread is None */