bdiff: don't check border condition in loop
This is pretty much a copy of d500ddae7494, just to a different loop.
The condition `p == plast` (`plast == a + len - 1`) was only true on
the final iteration of the loop. So it was wasteful to check for it
on every iteration. We decrease the iteration count by 1 and add an
explicit check for `p == plast` after the loop.
Again, we see modest wins.
From the mozilla-unified repository:
$ perfbdiff -m 3041e4d59df2
! wall 0.035502 comb 0.040000 user 0.040000 sys 0.000000 (best of 100)
! wall 0.030480 comb 0.030000 user 0.030000 sys 0.000000 (best of 100)
$ perfbdiff 0e9928989e9c --alldata --count 100
! wall 4.097394 comb 4.100000 user 4.100000 sys 0.000000 (best of 3)
! wall 3.597798 comb 3.600000 user 3.600000 sys 0.000000 (best of 3)
The 2nd example throws a total of ~3.3GB of data at bdiff. This
change increases the throughput from ~811 MB/s to ~924 MB/s.
#!/usr/bin/env python
# Copyright (c) 2016-present, Gregory Szorc
# All rights reserved.
#
# This software may be modified and distributed under the terms
# of the BSD license. See the LICENSE file for details.
from setuptools import setup
try:
import cffi
except ImportError:
cffi = None
import setup_zstd
# Code for obtaining the Extension instance is in its own module to
# facilitate reuse in other projects.
extensions = [setup_zstd.get_c_extension()]
if cffi:
import make_cffi
extensions.append(make_cffi.ffi.distutils_extension())
version = None
with open('c-ext/python-zstandard.h', 'r') as fh:
for line in fh:
if not line.startswith('#define PYTHON_ZSTANDARD_VERSION'):
continue
version = line.split()[2][1:-1]
break
if not version:
raise Exception('could not resolve package version; '
'this should never happen')
setup(
name='zstandard',
version=version,
description='Zstandard bindings for Python',
long_description=open('README.rst', 'r').read(),
url='https://github.com/indygreg/python-zstandard',
author='Gregory Szorc',
author_email='gregory.szorc@gmail.com',
license='BSD',
classifiers=[
'Development Status :: 4 - Beta',
'Intended Audience :: Developers',
'License :: OSI Approved :: BSD License',
'Programming Language :: C',
'Programming Language :: Python :: 2.6',
'Programming Language :: Python :: 2.7',
'Programming Language :: Python :: 3.3',
'Programming Language :: Python :: 3.4',
'Programming Language :: Python :: 3.5',
],
keywords='zstandard zstd compression',
ext_modules=extensions,
test_suite='tests',
)