From fa3b5149f2717387e172c4818505bbff941c90f3 Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Wed, 23 Jun 2021 10:26:07 +0200 Subject: [PATCH] bpo-39947: Remove old private trashcan C API functions Remove 4 C API private trashcan functions which were only kept for the backward compatibility of the stable ABI with Python 3.8 and older, since the trashcan API was not usable with the limited C API on Python 3.8 and older. The trashcan API was excluded from the limited C API in Python 3.9. Removed functions: * _PyTrash_deposit_object() * _PyTrash_destroy_chain() * _PyTrash_thread_deposit_object() * _PyTrash_thread_destroy_chain() The trashcan C API was never usable with the limited C API, since old trashcan macros accessed directly PyThreadState members like "_tstate->trash_delete_nesting", whereas the PyThreadState structure is opaque in the limited C API. Exclude also the PyTrash_UNWIND_LEVEL constant from the C API. The trashcan C API was modified in Python 3.9 by commit 38965ec5411da60d312b59be281f3510d58e0cf1 and in Python 3.10 by commit ed1a5a5baca8f61e9a99c5be3adc16b1801514fe to hide implementation details. --- Include/cpython/object.h | 16 +----- .../2021-06-23-10-31-45.bpo-39947.je_HMo.rst | 20 +++++++ Misc/stable_abi.txt | 12 ---- Objects/object.c | 56 +++---------------- PC/python3dll.c | 4 -- 5 files changed, 30 insertions(+), 78 deletions(-) create mode 100644 Misc/NEWS.d/next/C API/2021-06-23-10-31-45.bpo-39947.je_HMo.rst diff --git a/Include/cpython/object.h b/Include/cpython/object.h index 84c60e55d5c9df..75cd0f9002215b 100644 --- a/Include/cpython/object.h +++ b/Include/cpython/object.h @@ -493,8 +493,8 @@ without deallocating anything (and so unbounded call-stack depth is avoided). When the call stack finishes unwinding again, code generated by the END macro notices this, and calls another routine to deallocate all the objects that may have been added to the list of deferred deallocations. In effect, a -chain of N deallocations is broken into (N-1)/(PyTrash_UNWIND_LEVEL-1) pieces, -with the call stack never exceeding a depth of PyTrash_UNWIND_LEVEL. +chain of N deallocations is broken into (N-1)/(_PyTrash_UNWIND_LEVEL-1) pieces, +with the call stack never exceeding a depth of _PyTrash_UNWIND_LEVEL. Since the tp_dealloc of a subclass typically calls the tp_dealloc of the base class, we need to ensure that the trashcan is only triggered on the tp_dealloc @@ -503,16 +503,6 @@ partially-deallocated object. To check this, the tp_dealloc function must be passed as second argument to Py_TRASHCAN_BEGIN(). */ -/* This is the old private API, invoked by the macros before 3.2.4. - Kept for binary compatibility of extensions using the stable ABI. */ -PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*); -PyAPI_FUNC(void) _PyTrash_destroy_chain(void); - -/* This is the old private API, invoked by the macros before 3.9. - Kept for binary compatibility of extensions using the stable ABI. */ -PyAPI_FUNC(void) _PyTrash_thread_deposit_object(PyObject*); -PyAPI_FUNC(void) _PyTrash_thread_destroy_chain(void); - /* Forward declarations for PyThreadState */ struct _ts; @@ -522,8 +512,6 @@ PyAPI_FUNC(void) _PyTrash_end(struct _ts *tstate); /* Python 3.10 private API, invoked by the Py_TRASHCAN_BEGIN(). */ PyAPI_FUNC(int) _PyTrash_cond(PyObject *op, destructor dealloc); -#define PyTrash_UNWIND_LEVEL 50 - #define Py_TRASHCAN_BEGIN_CONDITION(op, cond) \ do { \ PyThreadState *_tstate = NULL; \ diff --git a/Misc/NEWS.d/next/C API/2021-06-23-10-31-45.bpo-39947.je_HMo.rst b/Misc/NEWS.d/next/C API/2021-06-23-10-31-45.bpo-39947.je_HMo.rst new file mode 100644 index 00000000000000..43adbffc7cce24 --- /dev/null +++ b/Misc/NEWS.d/next/C API/2021-06-23-10-31-45.bpo-39947.je_HMo.rst @@ -0,0 +1,20 @@ +Remove 4 private trashcan C API functions which were only kept for the backward +compatibility of the stable ABI with Python 3.8 and older, since the trashcan +API was not usable with the limited C API on Python 3.8 and older. The +trashcan API was excluded from the limited C API in Python 3.9. + +Removed functions: + +* _PyTrash_deposit_object() +* _PyTrash_destroy_chain() +* _PyTrash_thread_deposit_object() +* _PyTrash_thread_destroy_chain() + +The trashcan C API was never usable with the limited C API, since old trashcan +macros accessed directly :c:type:`PyThreadState` members like +``_tstate->trash_delete_nesting``, whereas the :c:type:`PyThreadState` +structure is opaque in the limited C API. + +Exclude also the the ``PyTrash_UNWIND_LEVEL`` constant from the C API. + +Patch by Victor Stinner. diff --git a/Misc/stable_abi.txt b/Misc/stable_abi.txt index 24c71d12e3ba75..f104f84e451da1 100644 --- a/Misc/stable_abi.txt +++ b/Misc/stable_abi.txt @@ -1602,12 +1602,6 @@ function _PyThreadState_Init function _PyThreadState_Prealloc added 3.2 abi_only -function _PyTrash_deposit_object - added 3.2 - abi_only -function _PyTrash_destroy_chain - added 3.2 - abi_only data _PyWeakref_CallableProxyType added 3.2 abi_only @@ -1920,12 +1914,6 @@ function Py_EncodeLocale added 3.7 # (and 3.6.1 and 3.5.3) function Py_SetPath added 3.7 # (and 3.6.1 and 3.5.3) -function _PyTrash_thread_deposit_object - added 3.7 # (and 3.6.1 and 3.5.3) - abi_only -function _PyTrash_thread_destroy_chain - added 3.7 # (and 3.6.1 and 3.5.3) - abi_only function PyErr_SetExcFromWindowsErr added 3.7 # (and 3.6.1 and 3.5.3) ifdef MS_WINDOWS diff --git a/Objects/object.c b/Objects/object.c index 854cc85b1cfa46..c87a83f225f14b 100644 --- a/Objects/object.c +++ b/Objects/object.c @@ -2092,25 +2092,13 @@ Py_ReprLeave(PyObject *obj) /* Trashcan support. */ -/* Add op to the _PyTrash_delete_later list. Called when the current +#define _PyTrash_UNWIND_LEVEL 50 + +/* Add op to the gcstate->trash_delete_later list. Called when the current * call-stack depth gets large. op must be a currently untracked gc'ed * object, with refcount 0. Py_DECREF must already have been called on it. */ -void -_PyTrash_deposit_object(PyObject *op) -{ - PyInterpreterState *interp = _PyInterpreterState_GET(); - struct _gc_runtime_state *gcstate = &interp->gc; - - _PyObject_ASSERT(op, _PyObject_IS_GC(op)); - _PyObject_ASSERT(op, !_PyObject_GC_IS_TRACKED(op)); - _PyObject_ASSERT(op, Py_REFCNT(op) == 0); - _PyGCHead_SET_PREV(_Py_AS_GC(op), gcstate->trash_delete_later); - gcstate->trash_delete_later = op; -} - -/* The equivalent API, using per-thread state recursion info */ -void +static void _PyTrash_thread_deposit_object(PyObject *op) { PyThreadState *tstate = _PyThreadState_GET(); @@ -2121,37 +2109,9 @@ _PyTrash_thread_deposit_object(PyObject *op) tstate->trash_delete_later = op; } -/* Deallocate all the objects in the _PyTrash_delete_later list. Called when - * the call-stack unwinds again. - */ -void -_PyTrash_destroy_chain(void) -{ - PyInterpreterState *interp = _PyInterpreterState_GET(); - struct _gc_runtime_state *gcstate = &interp->gc; - - while (gcstate->trash_delete_later) { - PyObject *op = gcstate->trash_delete_later; - destructor dealloc = Py_TYPE(op)->tp_dealloc; - - gcstate->trash_delete_later = - (PyObject*) _PyGCHead_PREV(_Py_AS_GC(op)); - - /* Call the deallocator directly. This used to try to - * fool Py_DECREF into calling it indirectly, but - * Py_DECREF was already called on this object, and in - * assorted non-release builds calling Py_DECREF again ends - * up distorting allocation statistics. - */ - _PyObject_ASSERT(op, Py_REFCNT(op) == 0); - ++gcstate->trash_delete_nesting; - (*dealloc)(op); - --gcstate->trash_delete_nesting; - } -} - -/* The equivalent API, using per-thread state recursion info */ -void +/* Deallocate all the objects in the gcstate->trash_delete_later list. + * Called when the call-stack unwinds again. */ +static void _PyTrash_thread_destroy_chain(void) { PyThreadState *tstate = _PyThreadState_GET(); @@ -2192,7 +2152,7 @@ _PyTrash_thread_destroy_chain(void) int _PyTrash_begin(PyThreadState *tstate, PyObject *op) { - if (tstate->trash_delete_nesting >= PyTrash_UNWIND_LEVEL) { + if (tstate->trash_delete_nesting >= _PyTrash_UNWIND_LEVEL) { /* Store the object (to be deallocated later) and jump past * Py_TRASHCAN_END, skipping the body of the deallocator */ _PyTrash_thread_deposit_object(op); diff --git a/PC/python3dll.c b/PC/python3dll.c index 378669c27f0544..0ebb56efaecb2c 100755 --- a/PC/python3dll.c +++ b/PC/python3dll.c @@ -37,10 +37,6 @@ EXPORT_FUNC(_PyObject_NewVar) EXPORT_FUNC(_PyState_AddModule) EXPORT_FUNC(_PyThreadState_Init) EXPORT_FUNC(_PyThreadState_Prealloc) -EXPORT_FUNC(_PyTrash_deposit_object) -EXPORT_FUNC(_PyTrash_destroy_chain) -EXPORT_FUNC(_PyTrash_thread_deposit_object) -EXPORT_FUNC(_PyTrash_thread_destroy_chain) EXPORT_FUNC(Py_AddPendingCall) EXPORT_FUNC(Py_AtExit) EXPORT_FUNC(Py_BuildValue)