Skip to content

gh-132108: Add Buffer Protocol support to int.from_bytes to improve performance #132109

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 4 commits into
base: main
Choose a base branch
from
Open

gh-132108: Add Buffer Protocol support to int.from_bytes to improve performance #132109

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
d898d27
gh-132108: Add Buffer Protocol support to int.from_bytes
cmaloney Apr 5, 2025
b078ea1
Apply suggestions from code review
cmaloney Apr 7, 2025
e6ef5e1
Check bytes exact first to speed up that case
cmaloney Apr 9, 2025
9c511b1
Tweak comments, fix PEP-7 formatting
cmaloney Apr 22, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2025-04-04-20-38-29.gh-issue-132108.UwZIQy.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Speed up :meth:`int.from_bytes` when passed a bytes-like object such as a
:class:`bytearray`.
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
Speed up :meth:`int.from_bytes` when passed a bytes-like object such as a
:class:`bytearray`.
Speed up :meth:`int.from_bytes` when passed a bytes-like object such as
:class:`bytes` and :class:`bytearray`.

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I do not think that it affects bytes.

29 changes: 21 additions & 8 deletions Objects/longobject.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6439,6 +6439,7 @@ int_from_bytes_impl(PyTypeObject *type, PyObject *bytes_obj,
{
int little_endian;
PyObject *long_obj, *bytes;
Py_buffer view;

if (byteorder == NULL)
little_endian = 0;
Expand All @@ -6452,14 +6453,26 @@ int_from_bytes_impl(PyTypeObject *type, PyObject *bytes_obj,
return NULL;
}

bytes = PyObject_Bytes(bytes_obj);
if (bytes == NULL)
return NULL;

long_obj = _PyLong_FromByteArray(
(unsigned char *)PyBytes_AS_STRING(bytes), Py_SIZE(bytes),
little_endian, is_signed);
Py_DECREF(bytes);
/* Use buffer protocol to avoid copies. */
if (PyObject_CheckBuffer(bytes_obj)) {
if (PyObject_GetBuffer(bytes_obj, &view, PyBUF_SIMPLE) != 0) {
return NULL;
}
long_obj = _PyLong_FromByteArray(view.buf, view.len, little_endian,
is_signed);
PyBuffer_Release(&view);
}
else {
/* fallback: Construct a bytes then convert. */
bytes = PyObject_Bytes(bytes_obj);
if (bytes == NULL) {
return NULL;
}
long_obj = _PyLong_FromByteArray(
(unsigned char *)PyBytes_AS_STRING(bytes), Py_SIZE(bytes),
little_endian, is_signed);
Py_DECREF(bytes);
}

if (long_obj != NULL && type != &PyLong_Type) {
Py_SETREF(long_obj, PyObject_CallOneArg((PyObject *)type, long_obj));
Expand Down
Loading