cpython/Include/internal/pycore_unicodeobject.h
Petr Viktorin 49f6beb56a
[3.12] gh-113993: Make interned strings mortal (GH-120520, GH-121364, GH-121903, GH-122303) (#123065)
This backports several PRs for gh-113993, making interned strings mortal so they can be garbage-collected when no longer needed.

* Allow interned strings to be mortal, and fix related issues (GH-120520)

  * Add an InternalDocs file describing how interning should work and how to use it.

  * Add internal functions to *explicitly* request what kind of interning is done:
    - `_PyUnicode_InternMortal`
    - `_PyUnicode_InternImmortal`
    - `_PyUnicode_InternStatic`

  * Switch uses of `PyUnicode_InternInPlace` to those.

  * Disallow using `_Py_SetImmortal` on strings directly.
    You should use `_PyUnicode_InternImmortal` instead:
    - Strings should be interned before immortalization, otherwise you're possibly
      interning a immortalizing copy.
    - `_Py_SetImmortal` doesn't handle the `SSTATE_INTERNED_MORTAL` to
      `SSTATE_INTERNED_IMMORTAL` update, and those flags can't be changed in
      backports, as they are now part of public API and version-specific ABI.

  * Add private `_only_immortal` argument for `sys.getunicodeinternedsize`, used in refleak test machinery.

   Make sure the statically allocated string singletons are unique. This means these sets are now disjoint:
    - `_Py_ID`
    - `_Py_STR` (including the empty string)
    - one-character latin-1 singletons

    Now, when you intern a singleton, that exact singleton will be interned.

  * Add a `_Py_LATIN1_CHR` macro, use it instead of `_Py_ID`/`_Py_STR` for one-character latin-1 singletons everywhere (including Clinic).

  * Intern `_Py_STR` singletons at startup.

  * Beef up the tests. Cover internal details (marked with `@cpython_only`).

  * Add lots of assertions

* Don't immortalize in PyUnicode_InternInPlace; keep immortalizing in other API (GH-121364)

  * Switch PyUnicode_InternInPlace to _PyUnicode_InternMortal, clarify docs

  * Document immortality in some functions that take `const char *`

  This is PyUnicode_InternFromString;
  PyDict_SetItemString, PyObject_SetAttrString;
  PyObject_DelAttrString; PyUnicode_InternFromString;
  and the PyModule_Add convenience functions.

  Always point out a non-immortalizing alternative.

  * Don't immortalize user-provided attr names in _ctypes

* Immortalize names in code objects to avoid crash (GH-121903)

* Intern latin-1 one-byte strings at startup (GH-122303)

There are some 3.12-specific changes, mainly to allow statically allocated strings in deepfreeze. (In 3.13, deepfreeze switched to the general `_Py_ID`/`_Py_STR`.)

Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
2024-09-27 13:28:48 -07:00

83 lines
2.5 KiB
C

#ifndef Py_INTERNAL_UNICODEOBJECT_H
#define Py_INTERNAL_UNICODEOBJECT_H
#ifdef __cplusplus
extern "C" {
#endif
#ifndef Py_BUILD_CORE
# error "this header requires Py_BUILD_CORE define"
#endif
#include "pycore_fileutils.h" // _Py_error_handler
#include "pycore_ucnhash.h" // _PyUnicode_Name_CAPI
void _PyUnicode_ExactDealloc(PyObject *op);
Py_ssize_t _PyUnicode_InternedSize(void);
Py_ssize_t _PyUnicode_InternedSize_Immortal(void);
/* runtime lifecycle */
extern void _PyUnicode_InitState(PyInterpreterState *);
extern PyStatus _PyUnicode_InitGlobalObjects(PyInterpreterState *);
extern PyStatus _PyUnicode_InitInternDict(PyInterpreterState *);
extern PyStatus _PyUnicode_InitTypes(PyInterpreterState *);
extern void _PyUnicode_Fini(PyInterpreterState *);
extern void _PyUnicode_FiniTypes(PyInterpreterState *);
extern PyTypeObject _PyUnicodeASCIIIter_Type;
/* Interning */
// All these are "ref-neutral", like the public PyUnicode_InternInPlace.
// Explicit interning routines:
PyAPI_FUNC(void) _PyUnicode_InternMortal(PyInterpreterState *interp, PyObject **);
PyAPI_FUNC(void) _PyUnicode_InternImmortal(PyInterpreterState *interp, PyObject **);
// Left here to help backporting:
PyAPI_FUNC(void) _PyUnicode_InternInPlace(PyInterpreterState *interp, PyObject **p);
// Only for statically allocated strings:
extern void _PyUnicode_InternStatic(PyInterpreterState *interp, PyObject **);
/* other API */
struct _Py_unicode_runtime_ids {
PyThread_type_lock lock;
// next_index value must be preserved when Py_Initialize()/Py_Finalize()
// is called multiple times: see _PyUnicode_FromId() implementation.
Py_ssize_t next_index;
};
struct _Py_unicode_runtime_state {
struct _Py_unicode_runtime_ids ids;
};
/* fs_codec.encoding is initialized to NULL.
Later, it is set to a non-NULL string by _PyUnicode_InitEncodings(). */
struct _Py_unicode_fs_codec {
char *encoding; // Filesystem encoding (encoded to UTF-8)
int utf8; // encoding=="utf-8"?
char *errors; // Filesystem errors (encoded to UTF-8)
_Py_error_handler error_handler;
};
struct _Py_unicode_ids {
Py_ssize_t size;
PyObject **array;
};
struct _Py_unicode_state {
struct _Py_unicode_fs_codec fs_codec;
_PyUnicode_Name_CAPI *ucnhash_capi;
// Unicode identifiers (_Py_Identifier): see _PyUnicode_FromId()
struct _Py_unicode_ids ids;
};
extern void _PyUnicode_ClearInterned(PyInterpreterState *interp);
#ifdef __cplusplus
}
#endif
#endif /* !Py_INTERNAL_UNICODEOBJECT_H */