6cb62f2697
Please note that this is a squshed commit and the work of: Symbolist, macdiesel, nedbat, doctoryes, muzaffaryousaf and muhammad-ammar
89 lines
3.7 KiB
Python
89 lines
3.7 KiB
Python
"""
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This module aims to give a little more fine-tuned control of caching and cache
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invalidation. Import these instead of django.core.cache.
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Note that 'default' is being preserved for user session caching, which we're
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not migrating so as not to inconvenience users by logging them all out.
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"""
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import urllib
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from functools import wraps
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from django.conf import settings
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from django.core import cache
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# If we can't find a 'general' CACHE defined in settings.py, we simply fall back
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# to returning the default cache. This will happen with dev machines.
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from django.utils.translation import get_language
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try:
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cache = cache.caches['general'] # pylint: disable=invalid-name
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except Exception:
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cache = cache.cache
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def cache_if_anonymous(*get_parameters):
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"""Cache a page for anonymous users.
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Many of the pages in edX are identical when the user is not logged
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in, but should not be cached when the user is logged in (because
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of the navigation bar at the top with the username).
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The django middleware cache does not handle this correctly, because
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we access the session to put the csrf token in the header. This adds
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the cookie to the vary header, and so every page is cached seperately
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for each user (because each user has a different csrf token).
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Optionally, provide a series of GET parameters as arguments to cache
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pages with these GET parameters separately.
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Note that this decorator should only be used on views that do not
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contain the csrftoken within the html. The csrf token can be included
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in the header by ordering the decorators as such:
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@ensure_csrftoken
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@cache_if_anonymous()
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def myView(request):
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"""
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def decorator(view_func):
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"""The outer wrapper, used to allow the decorator to take optional arguments."""
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@wraps(view_func)
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def wrapper(request, *args, **kwargs):
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"""The inner wrapper, which wraps the view function."""
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# Certificate authentication uses anonymous pages,
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# specifically the branding index, to do authentication.
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# If that page is cached the authentication doesn't
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# happen, so we disable the cache when that feature is enabled.
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if (
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not request.user.is_authenticated() and
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not settings.FEATURES['AUTH_USE_CERTIFICATES']
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):
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# Use the cache. The same view accessed through different domain names may
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# return different things, so include the domain name in the key.
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domain = str(request.META.get('HTTP_HOST')) + '.'
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cache_key = domain + "cache_if_anonymous." + get_language() + '.' + request.path
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# Include the values of GET parameters in the cache key.
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for get_parameter in get_parameters:
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parameter_value = request.GET.get(get_parameter)
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if parameter_value is not None:
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# urlencode expects data to be of type str, and doesn't deal well with Unicode data
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# since it doesn't provide a way to specify an encoding.
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cache_key = cache_key + '.' + urllib.urlencode({
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get_parameter: unicode(parameter_value).encode('utf-8')
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})
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response = cache.get(cache_key) # pylint: disable=maybe-no-member
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if not response:
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response = view_func(request, *args, **kwargs)
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cache.set(cache_key, response, 60 * 3) # pylint: disable=maybe-no-member
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return response
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else:
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# Don't use the cache.
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return view_func(request, *args, **kwargs)
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return wrapper
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return decorator
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