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bpo-45953: Statically allocate and initialize global bytes objects. (gh-30096)

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The empty bytes object (b'') and the 256 one-character bytes objects were allocated at runtime init.  Now we statically allocate and initialize them.

https://bugs.python.org/issue45953
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Eric Snow 2022-01-11 09:37:24 -07:00 • committed by GitHub
parent 6f05e1ec19
commit cf496d657a
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 294 additions and 96 deletions
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92
Objects/bytesobject.c
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@ -5,9 +5,9 @@
#include "Python.h"
#include "pycore_abstract.h" // _PyIndex_Check()
#include "pycore_bytes_methods.h" // _Py_bytes_startswith()
#include "pycore_bytesobject.h" // struct _Py_bytes_state
#include "pycore_call.h" // _PyObject_CallNoArgs()
#include "pycore_format.h" // F_LJUST
#include "pycore_global_objects.h" // _Py_GET_GLOBAL_OBJECT()
#include "pycore_initconfig.h" // _PyStatus_OK()
#include "pycore_long.h" // _PyLong_DigitValue
#include "pycore_object.h" // _PyObject_GC_TRACK
@ -38,49 +38,24 @@ Py_LOCAL_INLINE(Py_ssize_t) _PyBytesWriter_GetSize(_PyBytesWriter *writer,
char *str);
static struct _Py_bytes_state*
get_bytes_state(void)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
return &interp->bytes;
}
#define CHARACTERS _Py_SINGLETON(bytes_characters)
#define CHARACTER(ch) \
((PyBytesObject *)&(CHARACTERS[ch]));
#define EMPTY (&_Py_SINGLETON(bytes_empty))
// Return a borrowed reference to the empty bytes string singleton.
static inline PyObject* bytes_get_empty(void)
{
struct _Py_bytes_state *state = get_bytes_state();
// bytes_get_empty() must not be called before _PyBytes_Init()
// or after _PyBytes_Fini()
assert(state->empty_string != NULL);
return state->empty_string;
return &EMPTY->ob_base.ob_base;
}
// Return a strong reference to the empty bytes string singleton.
static inline PyObject* bytes_new_empty(void)
{
PyObject *empty = bytes_get_empty();
Py_INCREF(empty);
return (PyObject *)empty;
}
static int
bytes_create_empty_string_singleton(struct _Py_bytes_state *state)
{
// Create the empty bytes string singleton
PyBytesObject *op = (PyBytesObject *)PyObject_Malloc(PyBytesObject_SIZE);
if (op == NULL) {
return -1;
}
_PyObject_InitVar((PyVarObject*)op, &PyBytes_Type, 0);
op->ob_shash = -1;
op->ob_sval[0] = '\0';
assert(state->empty_string == NULL);
state->empty_string = (PyObject *)op;
return 0;
Py_INCREF(EMPTY);
return (PyObject *)EMPTY;
}
@ -148,12 +123,9 @@ PyBytes_FromStringAndSize(const char *str, Py_ssize_t size)
return NULL;
}
if (size == 1 && str != NULL) {
struct _Py_bytes_state *state = get_bytes_state();
op = state->characters[*str & UCHAR_MAX];
if (op != NULL) {
Py_INCREF(op);
return (PyObject *)op;
}
op = CHARACTER(*str & 255);
Py_INCREF(op);
return (PyObject *)op;
}
if (size == 0) {
return bytes_new_empty();
@ -166,12 +138,6 @@ PyBytes_FromStringAndSize(const char *str, Py_ssize_t size)
return (PyObject *) op;
memcpy(op->ob_sval, str, size);
/* share short strings */
if (size == 1) {
struct _Py_bytes_state *state = get_bytes_state();
Py_INCREF(op);
state->characters[*str & UCHAR_MAX] = op;
}
return (PyObject *) op;
}
@ -189,16 +155,13 @@ PyBytes_FromString(const char *str)
return NULL;
}
struct _Py_bytes_state *state = get_bytes_state();
if (size == 0) {
return bytes_new_empty();
}
else if (size == 1) {
op = state->characters[*str & UCHAR_MAX];
if (op != NULL) {
Py_INCREF(op);
return (PyObject *)op;
}
op = CHARACTER(*str & 255);
Py_INCREF(op);
return (PyObject *)op;
}
/* Inline PyObject_NewVar */
@ -209,12 +172,6 @@ PyBytes_FromString(const char *str)
_PyObject_InitVar((PyVarObject*)op, &PyBytes_Type, size);
op->ob_shash = -1;
memcpy(op->ob_sval, str, size+1);
/* share short strings */
if (size == 1) {
assert(state->characters[*str & UCHAR_MAX] == NULL);
Py_INCREF(op);
state->characters[*str & UCHAR_MAX] = op;
}
return (PyObject *) op;
}
@ -3086,17 +3043,6 @@ error:
}
PyStatus
_PyBytes_InitGlobalObjects(PyInterpreterState *interp)
{
struct _Py_bytes_state *state = &interp->bytes;
if (bytes_create_empty_string_singleton(state) < 0) {
return _PyStatus_NO_MEMORY();
}
return _PyStatus_OK();
}
PyStatus
_PyBytes_InitTypes(PyInterpreterState *interp)
{
@ -3116,16 +3062,6 @@ _PyBytes_InitTypes(PyInterpreterState *interp)
}
void
_PyBytes_Fini(PyInterpreterState *interp)
{
struct _Py_bytes_state* state = &interp->bytes;
for (int i = 0; i < UCHAR_MAX + 1; i++) {
Py_CLEAR(state->characters[i]);
}
Py_CLEAR(state->empty_string);
}
/*********************** Bytes Iterator ****************************/
typedef struct {