[Python-checkins] r67610 - in python/branches/py3k: Misc/NEWS Objects/bytesobject.c
mark.dickinson
python-checkins at python.org
Sat Dec 6 16:33:32 CET 2008
Author: mark.dickinson
Date: Sat Dec 6 16:33:31 2008
New Revision: 67610
Log:
Issue #4445: save 3 bytes of memory (on average) per bytes allocation.
(This is a forward port of r67601).
Modified:
python/branches/py3k/Misc/NEWS
python/branches/py3k/Objects/bytesobject.c
Modified: python/branches/py3k/Misc/NEWS
==============================================================================
--- python/branches/py3k/Misc/NEWS (original)
+++ python/branches/py3k/Misc/NEWS Sat Dec 6 16:33:31 2008
@@ -12,6 +12,11 @@
Core and Builtins
-----------------
+- Issue #4445: Replace "sizeof(PyBytesObject)" with
+ "offsetof(PyBytesObject, ob_sval) + 1" when allocating memory for
+ bytes instances. On a typical machine this saves 3 bytes of memory
+ (on average) per allocation of a bytes instance.
+
- Issue #4533: File read operation was dreadfully slow due to a slowly
growing read buffer. Fixed by using the same growth rate algorithm as
Python 2.x.
Modified: python/branches/py3k/Objects/bytesobject.c
==============================================================================
--- python/branches/py3k/Objects/bytesobject.c (original)
+++ python/branches/py3k/Objects/bytesobject.c Sat Dec 6 16:33:31 2008
@@ -5,6 +5,7 @@
#include "Python.h"
#include "bytes_methods.h"
+#include <stddef.h>
static Py_ssize_t
_getbuffer(PyObject *obj, Py_buffer *view)
@@ -31,6 +32,14 @@
static PyBytesObject *characters[UCHAR_MAX + 1];
static PyBytesObject *nullstring;
+/* PyBytesObject_SIZE gives the basic size of a string; any memory allocation
+ for a string of length n should request PyBytesObject_SIZE + n bytes.
+
+ Using PyBytesObject_SIZE instead of sizeof(PyBytesObject) saves
+ 3 bytes per string allocation on a typical system.
+*/
+#define PyBytesObject_SIZE (offsetof(PyBytesObject, ob_sval) + 1)
+
/*
For both PyBytes_FromString() and PyBytes_FromStringAndSize(), the
parameter `size' denotes number of characters to allocate, not counting any
@@ -83,14 +92,14 @@
return (PyObject *)op;
}
- if (size > PY_SSIZE_T_MAX - sizeof(PyBytesObject)) {
+ if (size > PY_SSIZE_T_MAX - PyBytesObject_SIZE) {
PyErr_SetString(PyExc_OverflowError,
"byte string is too large");
return NULL;
}
/* Inline PyObject_NewVar */
- op = (PyBytesObject *)PyObject_MALLOC(sizeof(PyBytesObject) + size);
+ op = (PyBytesObject *)PyObject_MALLOC(PyBytesObject_SIZE + size);
if (op == NULL)
return PyErr_NoMemory();
PyObject_INIT_VAR(op, &PyBytes_Type, size);
@@ -117,7 +126,7 @@
assert(str != NULL);
size = strlen(str);
- if (size > PY_SSIZE_T_MAX - sizeof(PyBytesObject)) {
+ if (size > PY_SSIZE_T_MAX - PyBytesObject_SIZE) {
PyErr_SetString(PyExc_OverflowError,
"byte string is too long");
return NULL;
@@ -138,7 +147,7 @@
}
/* Inline PyObject_NewVar */
- op = (PyBytesObject *)PyObject_MALLOC(sizeof(PyBytesObject) + size);
+ op = (PyBytesObject *)PyObject_MALLOC(PyBytesObject_SIZE + size);
if (op == NULL)
return PyErr_NoMemory();
PyObject_INIT_VAR(op, &PyBytes_Type, size);
@@ -746,13 +755,12 @@
return (PyObject *)a;
}
nbytes = (size_t)size;
- if (nbytes + sizeof(PyBytesObject) <= nbytes) {
+ if (nbytes + PyBytesObject_SIZE <= nbytes) {
PyErr_SetString(PyExc_OverflowError,
"repeated bytes are too long");
return NULL;
}
- op = (PyBytesObject *)
- PyObject_MALLOC(sizeof(PyBytesObject) + nbytes);
+ op = (PyBytesObject *)PyObject_MALLOC(PyBytesObject_SIZE + nbytes);
if (op == NULL)
return PyErr_NoMemory();
PyObject_INIT_VAR(op, &PyBytes_Type, size);
@@ -2803,7 +2811,7 @@
string_sizeof(PyBytesObject *v)
{
Py_ssize_t res;
- res = sizeof(PyBytesObject) + Py_SIZE(v) * Py_TYPE(v)->tp_itemsize;
+ res = PyBytesObject_SIZE + Py_SIZE(v) * Py_TYPE(v)->tp_itemsize;
return PyLong_FromSsize_t(res);
}
@@ -3080,7 +3088,7 @@
PyTypeObject PyBytes_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"bytes",
- sizeof(PyBytesObject),
+ PyBytesObject_SIZE,
sizeof(char),
string_dealloc, /* tp_dealloc */
0, /* tp_print */
@@ -3175,7 +3183,7 @@
_Py_DEC_REFTOTAL;
_Py_ForgetReference(v);
*pv = (PyObject *)
- PyObject_REALLOC((char *)v, sizeof(PyBytesObject) + newsize);
+ PyObject_REALLOC((char *)v, PyBytesObject_SIZE + newsize);
if (*pv == NULL) {
PyObject_Del(v);
PyErr_NoMemory();
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