Python django.utils.lru_cache.lru_cache() Examples

def check_for_language(lang_code):
    """
    Checks whether there is a global language file for the given language
    code. This is used to decide whether a user-provided language is
    available.

    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/>.
    """
    # First, a quick check to make sure lang_code is well-formed (#21458)
    if lang_code is None or not language_code_re.search(lang_code):
        return False
    for path in all_locale_paths():
        if gettext_module.find('django', path, [to_locale(lang_code)]) is not None:
            return True
    return False 

def check_for_language(lang_code):
    """
    Checks whether there is a global language file for the given language
    code. This is used to decide whether a user-provided language is
    available.

    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/>.
    """
    # First, a quick check to make sure lang_code is well-formed (#21458)
    if lang_code is None or not language_code_re.search(lang_code):
        return False
    for path in all_locale_paths():
        if gettext_module.find('django', path, [to_locale(lang_code)]) is not None:
            return True
    return False 

def check_for_language(lang_code):
    """
    Checks whether there is a global language file for the given language
    code. This is used to decide whether a user-provided language is
    available.

    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/>.
    """
    # First, a quick check to make sure lang_code is well-formed (#21458)
    if lang_code is None or not language_code_re.search(lang_code):
        return False
    for path in all_locale_paths():
        if gettext_module.find('django', path, [to_locale(lang_code)]) is not None:
            return True
    return False 

def check_for_language(lang_code):
    """
    Checks whether there is a global language file for the given language
    code. This is used to decide whether a user-provided language is
    available.

    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/>.
    """
    # First, a quick check to make sure lang_code is well-formed (#21458)
    if lang_code is None or not language_code_re.search(lang_code):
        return False
    for path in all_locale_paths():
        if gettext_module.find('django', path, [to_locale(lang_code)]) is not None:
            return True
    return False 

def reset_hashers(self):
        """
        Wrapper to manually reset django's hasher lookup cache
        """
        # resets cache for .get_hashers() & .get_hashers_by_algorithm()
        from django.contrib.auth.hashers import reset_hashers
        reset_hashers(setting="PASSWORD_HASHERS")

        # reset internal caches
        super(DjangoContextAdapter, self).reset_hashers()

    #=============================================================================
    # django hashers helpers -- hasher lookup
    #=============================================================================

    # lru_cache()'ed by init 

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 lang_code:
        # If 'fr-ca' is not supported, try special fallback or language-only 'fr'.
        possible_lang_codes = [lang_code]
        try:
            possible_lang_codes.extend(LANG_INFO[lang_code]['fallback'])
        except KeyError:
            pass
        generic_lang_code = lang_code.split('-')[0]
        possible_lang_codes.append(generic_lang_code)
        supported_lang_codes = get_languages()

        for code in possible_lang_codes:
            if code in supported_lang_codes and check_for_language(code):
                return code
        if not strict:
            # if fr-fr is not supported, try fr-ca.
            for supported_code in supported_lang_codes:
                if supported_code.startswith(generic_lang_code + '-'):
                    return supported_code
    raise LookupError(lang_code) 

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 lang_code:
        # If 'fr-ca' is not supported, try special fallback or language-only 'fr'.
        possible_lang_codes = [lang_code]
        try:
            possible_lang_codes.extend(LANG_INFO[lang_code]['fallback'])
        except KeyError:
            pass
        generic_lang_code = lang_code.split('-')[0]
        possible_lang_codes.append(generic_lang_code)
        supported_lang_codes = get_languages()

        for code in possible_lang_codes:
            if code in supported_lang_codes and check_for_language(code):
                return code
        if not strict:
            # if fr-fr is not supported, try fr-ca.
            for supported_code in supported_lang_codes:
                if supported_code.startswith(generic_lang_code + '-'):
                    return supported_code
    raise LookupError(lang_code) 

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 lang_code:
        # If 'fr-ca' is not supported, try special fallback or language-only 'fr'.
        possible_lang_codes = [lang_code]
        try:
            possible_lang_codes.extend(LANG_INFO[lang_code]['fallback'])
        except KeyError:
            pass
        generic_lang_code = lang_code.split('-')[0]
        possible_lang_codes.append(generic_lang_code)
        supported_lang_codes = get_languages()

        for code in possible_lang_codes:
            if code in supported_lang_codes and check_for_language(code):
                return code
        if not strict:
            # if fr-fr is not supported, try fr-ca.
            for supported_code in supported_lang_codes:
                if supported_code.startswith(generic_lang_code + '-'):
                    return supported_code
    raise LookupError(lang_code) 

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 lang_code:
        # If 'fr-ca' is not supported, try special fallback or language-only 'fr'.
        possible_lang_codes = [lang_code]
        try:
            possible_lang_codes.extend(LANG_INFO[lang_code]['fallback'])
        except KeyError:
            pass
        generic_lang_code = lang_code.split('-')[0]
        possible_lang_codes.append(generic_lang_code)
        supported_lang_codes = get_languages()

        for code in possible_lang_codes:
            if code in supported_lang_codes and check_for_language(code):
                return code
        if not strict:
            # if fr-fr is not supported, try fr-ca.
            for supported_code in supported_lang_codes:
                if supported_code.startswith(generic_lang_code + '-'):
                    return supported_code
    raise LookupError(lang_code) 

def __init__(self, context=None, get_user_category=None, **kwds):

        # init log
        self.log = logging.getLogger(__name__ + ".DjangoContextAdapter")

        # init parent, filling in default context object
        if context is None:
            context = CryptContext()
        super(DjangoContextAdapter, self).__init__(context=context, **kwds)

        # setup user category
        if get_user_category:
            assert callable(get_user_category)
            self.get_user_category = get_user_category

        # install lru cache wrappers
        from django.utils.lru_cache import lru_cache
        self.get_hashers = lru_cache()(self.get_hashers)

        # get copy of original make_password
        from django.contrib.auth.hashers import make_password
        if make_password.__module__.startswith("passlib."):
            make_password = _PatchManager.peek_unpatched_func(make_password)
        self._orig_make_password = make_password

        # get other django helpers
        from django.contrib.auth.hashers import is_password_usable
        self.is_password_usable = is_password_usable

        # init manager
        mlog = logging.getLogger(__name__ + ".DjangoContextAdapter._manager")
        self._manager = _PatchManager(log=mlog) 

def ignore_unhashable_lru_cache(maxsize: int=128, typed: bool=False) -> DECORATOR:
    """
    This is a wrapper over lru_cache function. It adds following features on
    top of lru_cache:

        * It will not cache result of functions with unhashable arguments.
        * It will clear cache whenever zerver.lib.cache.KEY_PREFIX changes.
    """
    internal_decorator = lru_cache(maxsize=maxsize, typed=typed)

    def decorator(user_function: Callable[..., Any]) -> Callable[..., Any]:
        if settings.DEVELOPMENT and not settings.TEST_SUITE:  # nocoverage
            # In the development environment, we want every file
            # change to refresh the source files from disk.
            return user_function
        cache_enabled_user_function = internal_decorator(user_function)

        def wrapper(*args: Any, **kwargs: Any) -> Any:
            if not hasattr(cache_enabled_user_function, 'key_prefix'):
                cache_enabled_user_function.key_prefix = KEY_PREFIX

            if cache_enabled_user_function.key_prefix != KEY_PREFIX:
                # Clear cache when cache.KEY_PREFIX changes. This is used in
                # tests.
                cache_enabled_user_function.cache_clear()
                cache_enabled_user_function.key_prefix = KEY_PREFIX

            try:
                return cache_enabled_user_function(*args, **kwargs)
            except TypeError:
                # args or kwargs contains an element which is unhashable. In
                # this case we don't cache the result.
                pass

            # Deliberately calling this function from outside of exception
            # handler to get a more descriptive traceback. Otherwise traceback
            # can include the exception from cached_enabled_user_function as
            # well.
            return user_function(*args, **kwargs)

        setattr(wrapper, 'cache_info', cache_enabled_user_function.cache_info)
        setattr(wrapper, 'cache_clear', cache_enabled_user_function.cache_clear)
        return wrapper

    return decorator