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Fixed #21389 -- Accept most valid language codes 

By removing the 'supported' keyword from the detection methods and only relying
on a cached settings.LANGUAGES, the speed of said methods has been improved;
around 4x raw performance. This allows us to stop checking Python's incomplete
list of locales, and rely on a less restrictive regular expression for
accepting certain locales.

HTTP Accept-Language is defined as being case-insensitive, based on this fact
extra performance improvements have been made; it wouldn't make sense to
check for case differences.
This commit is contained in:
Bouke Haarsma 2013-11-12 07:54:01 +01:00 committed by Claude Paroz
parent 48a8b714d4
commit 2bab9d6d9e
6 changed files with 68 additions and 58 deletions
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7
django/middleware/locale.py
View File

@ -1,7 +1,5 @@
"This is the locale selecting middleware that will look at accept headers"
from collections import OrderedDict
from django.conf import settings
from django.core.urlresolvers import (is_valid_path, get_resolver,
LocaleRegexURLResolver)
@ -21,7 +19,6 @@ class LocaleMiddleware(object):
response_redirect_class = HttpResponseRedirect
def __init__(self):
self._supported_languages = OrderedDict(settings.LANGUAGES)
self._is_language_prefix_patterns_used = False
for url_pattern in get_resolver(None).url_patterns:
if isinstance(url_pattern, LocaleRegexURLResolver):
@ -37,9 +34,7 @@ class LocaleMiddleware(object):
def process_response(self, request, response):
language = translation.get_language()
language_from_path = translation.get_language_from_path(
request.path_info, supported=self._supported_languages
)
language_from_path = translation.get_language_from_path(request.path_info)
if (response.status_code == 404 and not language_from_path
and self.is_language_prefix_patterns_used()):
urlconf = getattr(request, 'urlconf', None)

4
django/utils/translation/__init__.py
View File

@ -187,8 +187,8 @@ def get_language_from_request(request, check_path=False):
return _trans.get_language_from_request(request, check_path)
def get_language_from_path(path, supported=None):
return _trans.get_language_from_path(path, supported=supported)
def get_language_from_path(path):
return _trans.get_language_from_path(path)
def templatize(src, origin=None):

2
django/utils/translation/trans_null.py
View File

@ -68,5 +68,5 @@ def get_language_from_request(request, check_path=False):
return settings.LANGUAGE_CODE
def get_language_from_path(request, supported=None):
def get_language_from_path(request):
return None

83
django/utils/translation/trans_real.py
View File

@ -2,7 +2,6 @@
from __future__ import unicode_literals
from collections import OrderedDict
import locale
import os
import re
import sys
@ -29,9 +28,9 @@ _active = local()
# The default translation is based on the settings file.
_default = None
# This is a cache for normalized accept-header languages to prevent multiple
# file lookups when checking the same locale on repeated requests.
_accepted = {}
# This is a cache of settings.LANGUAGES in an OrderedDict for easy lookups by
# key
_supported = None
# magic gettext number to separate context from message
CONTEXT_SEPARATOR = "\x04"
@ -63,9 +62,11 @@ def reset_cache(**kwargs):
Reset global state when LANGUAGES setting has been changed, as some
languages should no longer be accepted.
"""
if kwargs['setting'] == 'LANGUAGES':
global _accepted
_accepted = {}
if kwargs['setting'] in ('LANGUAGES', 'LANGUAGE_CODE'):
global _supported
_supported = None
check_for_language.cache_clear()
get_supported_language_variant.cache_clear()
def to_locale(language, to_lower=False):
@ -388,7 +389,7 @@ def all_locale_paths():
return [globalpath] + list(settings.LOCALE_PATHS)
@lru_cache.lru_cache(maxsize=None)
@lru_cache.lru_cache()
def check_for_language(lang_code):
"""
Checks whether there is a global language file for the given language
@ -404,39 +405,42 @@ def check_for_language(lang_code):
return False
def get_supported_language_variant(lang_code, supported=None, strict=False):
@lru_cache.lru_cache(maxsize=1000)
def get_supported_language_variant(lang_code, strict=False):
"""
Returns the language-code that's listed in supported languages, possibly
selecting a more generic variant. Raises LookupError if nothing found.
If `strict` is False (the default), the function will look for an alternative
country-specific variant when the currently checked is not found.
lru_cache should have a maxsize to prevent from memory exhaustion attacks,
as the provided language codes are taken from the HTTP request. See also
<https://www.djangoproject.com/weblog/2007/oct/26/security-fix/>.
"""
if supported is None:
global _supported
if _supported is None:
from django.conf import settings
supported = OrderedDict(settings.LANGUAGES)
_supported = OrderedDict(settings.LANGUAGES)
if lang_code:
# some browsers use deprecated language codes -- #18419
replacement = _BROWSERS_DEPRECATED_LOCALES.get(lang_code)
if lang_code not in supported and replacement in supported:
if lang_code not in _supported and replacement in _supported:
return replacement
# if fr-CA is not supported, try fr-ca; if that fails, fallback to fr.
# if fr-ca is not supported, try fr.
generic_lang_code = lang_code.split('-')[0]
variants = (lang_code, lang_code.lower(), generic_lang_code,
generic_lang_code.lower())
for code in variants:
if code in supported and check_for_language(code):
for code in (lang_code, generic_lang_code):
if code in _supported and check_for_language(code):
return code
if not strict:
# if fr-fr is not supported, try fr-ca.
for supported_code in supported:
if supported_code.startswith((generic_lang_code + '-',
generic_lang_code.lower() + '-')):
for supported_code in _supported:
if supported_code.startswith(generic_lang_code + '-'):
return supported_code
raise LookupError(lang_code)
def get_language_from_path(path, supported=None, strict=False):
def get_language_from_path(path, strict=False):
"""
Returns the language-code if there is a valid language-code
found in the `path`.
@ -444,15 +448,12 @@ def get_language_from_path(path, supported=None, strict=False):
If `strict` is False (the default), the function will look for an alternative
country-specific variant when the currently checked is not found.
"""
if supported is None:
from django.conf import settings
supported = OrderedDict(settings.LANGUAGES)
regex_match = language_code_prefix_re.match(path)
if not regex_match:
return None
lang_code = regex_match.group(1)
try:
return get_supported_language_variant(lang_code, supported, strict=strict)
return get_supported_language_variant(lang_code, strict=strict)
except LookupError:
return None
@ -467,25 +468,26 @@ def get_language_from_request(request, check_path=False):
If check_path is True, the URL path prefix will be checked for a language
code, otherwise this is skipped for backwards compatibility.
"""
global _accepted
from django.conf import settings
supported = OrderedDict(settings.LANGUAGES)
global _supported
if _supported is None:
_supported = OrderedDict(settings.LANGUAGES)
if check_path:
lang_code = get_language_from_path(request.path_info, supported)
lang_code = get_language_from_path(request.path_info)
if lang_code is not None:
return lang_code
if hasattr(request, 'session'):
# for backwards compatibility django_language is also checked (remove in 1.8)
lang_code = request.session.get(LANGUAGE_SESSION_KEY, request.session.get('django_language'))
if lang_code in supported and lang_code is not None and check_for_language(lang_code):
if lang_code in _supported and lang_code is not None and check_for_language(lang_code):
return lang_code
lang_code = request.COOKIES.get(settings.LANGUAGE_COOKIE_NAME)
try:
return get_supported_language_variant(lang_code, supported)
return get_supported_language_variant(lang_code)
except LookupError:
pass
@ -494,29 +496,16 @@ def get_language_from_request(request, check_path=False):
if accept_lang == '*':
break
# 'normalized' is the root name of the locale in POSIX format (which is
# the format used for the directories holding the MO files).
normalized = locale.locale_alias.get(to_locale(accept_lang, True))
if not normalized:
if not language_code_re.search(accept_lang):
continue
# Remove the default encoding from locale_alias.
normalized = normalized.split('.')[0]
if normalized in _accepted:
# We've seen this locale before and have an MO file for it, so no
# need to check again.
return _accepted[normalized]
try:
accept_lang = get_supported_language_variant(accept_lang, supported)
return get_supported_language_variant(accept_lang)
except LookupError:
continue
else:
_accepted[normalized] = accept_lang
return accept_lang
try:
return get_supported_language_variant(settings.LANGUAGE_CODE, supported)
return get_supported_language_variant(settings.LANGUAGE_CODE)
except LookupError:
return settings.LANGUAGE_CODE
@ -732,7 +721,7 @@ def parse_accept_lang_header(lang_string):
Any format errors in lang_string results in an empty list being returned.
"""
result = []
pieces = accept_language_re.split(lang_string)
pieces = accept_language_re.split(lang_string.lower())
if pieces[-1]:
return []
for i in range(0, len(pieces) - 1, 3):

8
docs/releases/1.7.txt
View File

@ -1125,6 +1125,14 @@ Miscellaneous
For example, if you use multi-inheritance, you need to define custom primary
key fields on parent models, otherwise the default ``id`` fields will clash.
* :meth:`~django.utils.translation.parse_accept_lang_header` now returns
lowercase locales, instead of the case as it was provided. As locales should
be treated case-insensitive this allows us to speed up locale detection.
* :meth:`~django.utils.translation.get_language_from_path` and
:meth:`~django.utils.translation.trans_real.get_supported_language_variant`
now no longer have a ``supported`` argument.
.. _deprecated-features-1.7:
Features deprecated in 1.7

22
tests/i18n/tests.py
View File

@ -821,10 +821,10 @@ class MiscTests(TestCase):
p = trans_real.parse_accept_lang_header
# Good headers.
self.assertEqual([('de', 1.0)], p('de'))
self.assertEqual([('en-AU', 1.0)], p('en-AU'))
self.assertEqual([('en-au', 1.0)], p('en-AU'))
self.assertEqual([('es-419', 1.0)], p('es-419'))
self.assertEqual([('*', 1.0)], p('*;q=1.00'))
self.assertEqual([('en-AU', 0.123)], p('en-AU;q=0.123'))
self.assertEqual([('en-au', 0.123)], p('en-AU;q=0.123'))
self.assertEqual([('en-au', 0.5)], p('en-au;q=0.5'))
self.assertEqual([('en-au', 1.0)], p('en-au;q=1.0'))
self.assertEqual([('da', 1.0), ('en', 0.5), ('en-gb', 0.25)], p('da, en-gb;q=0.25, en;q=0.5'))
@ -884,6 +884,24 @@ class MiscTests(TestCase):
r.META = {'HTTP_ACCEPT_LANGUAGE': 'zh-cn,de'}
self.assertEqual(g(r), 'zh-cn')
r.META = {'HTTP_ACCEPT_LANGUAGE': 'NL'}
self.assertEqual('nl', g(r))
r.META = {'HTTP_ACCEPT_LANGUAGE': 'fy'}
self.assertEqual('fy', g(r))
r.META = {'HTTP_ACCEPT_LANGUAGE': 'ia'}
self.assertEqual('ia', g(r))
r.META = {'HTTP_ACCEPT_LANGUAGE': 'sr-latn'}
self.assertEqual('sr-latn', g(r))
r.META = {'HTTP_ACCEPT_LANGUAGE': 'zh-hans'}
self.assertEqual('zh-hans', g(r))
r.META = {'HTTP_ACCEPT_LANGUAGE': 'zh-hant'}
self.assertEqual('zh-hant', g(r))
@override_settings(
LANGUAGES=(
('en', 'English'),