Commit cb17f7ca authored by Honza Král's avatar Honza Král
Browse files

Fixed #14560 -- Enable HEAD requests to be cached properly. Thanks, codemonkey! 

Introducing ability to cache HEAD requests and GET requests separately by
adding the method to the cache key while preserving the functionality that HEAD
requests can use cached reponses generated by a GET request.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14391 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent 8a724802

django/middleware/cache.py

+12 −9
Original line number Diff line number Diff line
@@ -34,8 +34,8 @@ More details about how the caching works: 
  and effective way of avoiding the caching of the Django admin (and any other

  user-specific content).



* This middleware expects that a HEAD request is answered with a response

  exactly like the corresponding GET request.

* This middleware expects that a HEAD request is answered with the same response

  headers exactly like the corresponding GET request.



* When a hit occurs, a shallow copy of the original response object is returned

  from process_request.
@@ -71,12 +71,6 @@ class UpdateCacheMiddleware(object): 
        if not hasattr(request, '_cache_update_cache') or not request._cache_update_cache:

            # We don't need to update the cache, just return.

            return response

        if request.method != 'GET':

            # This is a stronger requirement than above. It is needed

            # because of interactions between this middleware and the

            # HTTPMiddleware, which throws the body of a HEAD-request

            # away before this middleware gets a chance to cache it.

            return response

        if not response.status_code == 200:

            return response

        # Try to get the timeout from the "max-age" section of the "Cache-
@@ -123,16 +117,25 @@ class FetchFromCacheMiddleware(object): 
            request._cache_update_cache = False

            return None # Don't cache requests from authenticated users.



        cache_key = get_cache_key(request, self.key_prefix)

        # try and get the cached GET response

        cache_key = get_cache_key(request, self.key_prefix, 'GET')



        if cache_key is None:

            request._cache_update_cache = True

            return None # No cache information available, need to rebuild.



        response = cache.get(cache_key, None)



        # if it wasn't found and we are looking for a HEAD, try looking just for that

        if response is None and request.method == 'HEAD':

            cache_key = get_cache_key(request, self.key_prefix, 'HEAD')

            response = cache.get(cache_key, None)



        if response is None:

            request._cache_update_cache = True

            return None # No cache information available, need to rebuild.



        # hit, return cached response

        request._cache_update_cache = False

        return response

django/utils/cache.py

+7 −7
Original line number Diff line number Diff line
@@ -143,7 +143,7 @@ def _i18n_cache_key_suffix(request, cache_key): 
        cache_key += '.%s' % getattr(request, 'LANGUAGE_CODE', get_language())

    return cache_key



def _generate_cache_key(request, headerlist, key_prefix):

def _generate_cache_key(request, method, headerlist, key_prefix):

    """Returns a cache key from the headers given in the header list."""

    ctx = md5_constructor()

    for header in headerlist:
@@ -151,8 +151,8 @@ def _generate_cache_key(request, headerlist, key_prefix): 
        if value is not None:

            ctx.update(value)

    path = md5_constructor(iri_to_uri(request.path))

    cache_key = 'views.decorators.cache.cache_page.%s.%s.%s' % (

        key_prefix, path.hexdigest(), ctx.hexdigest())

    cache_key = 'views.decorators.cache.cache_page.%s.%s.%s.%s' % (

        key_prefix, request.method, path.hexdigest(), ctx.hexdigest())

    return _i18n_cache_key_suffix(request, cache_key)



def _generate_cache_header_key(key_prefix, request):
@@ -162,7 +162,7 @@ def _generate_cache_header_key(key_prefix, request): 
        key_prefix, path.hexdigest())

    return _i18n_cache_key_suffix(request, cache_key)



def get_cache_key(request, key_prefix=None):

def get_cache_key(request, key_prefix=None, method='GET'):

    """

    Returns a cache key based on the request path. It can be used in the

    request phase because it pulls the list of headers to take into account
@@ -177,7 +177,7 @@ def get_cache_key(request, key_prefix=None): 
    cache_key = _generate_cache_header_key(key_prefix, request)

    headerlist = cache.get(cache_key, None)

    if headerlist is not None:

        return _generate_cache_key(request, headerlist, key_prefix)

        return _generate_cache_key(request, method, headerlist, key_prefix)

    else:

        return None
@@ -203,12 +203,12 @@ def learn_cache_key(request, response, cache_timeout=None, key_prefix=None): 
        headerlist = ['HTTP_'+header.upper().replace('-', '_')

                      for header in cc_delim_re.split(response['Vary'])]

        cache.set(cache_key, headerlist, cache_timeout)

        return _generate_cache_key(request, headerlist, key_prefix)

        return _generate_cache_key(request, request.method, headerlist, key_prefix)

    else:

        # if there is no Vary header, we still need a cache key

        # for the request.path

        cache.set(cache_key, [], cache_timeout)

        return _generate_cache_key(request, [], key_prefix)

        return _generate_cache_key(request, request.method, [], key_prefix)





def _to_tuple(s):

docs/topics/cache.txt

+3 −1
Original line number Diff line number Diff line
@@ -328,7 +328,9 @@ parameters. Optionally, if the ``CACHE_MIDDLEWARE_ANONYMOUS_ONLY`` setting is 
will be cached. This is a simple and effective way of disabling caching for any

user-specific pages (include Django's admin interface). Note that if you use

``CACHE_MIDDLEWARE_ANONYMOUS_ONLY``, you should make sure you've activated

``AuthenticationMiddleware``.

``AuthenticationMiddleware``. The cache middleware expects that a HEAD request

is answered with the same response headers exactly like the corresponding GET

request, in that case it could return cached GET response for HEAD request.



Additionally, the cache middleware automatically sets a few headers in each

``HttpResponse``:

tests/regressiontests/cache/tests.py

+64 −5
Original line number Diff line number Diff line
@@ -507,12 +507,13 @@ class CacheUtils(unittest.TestCase): 
        settings.CACHE_MIDDLEWARE_SECONDS = self.old_middleware_seconds

        settings.USE_I18N = self.orig_use_i18n



    def _get_request(self, path):

    def _get_request(self, path, method='GET'):

        request = HttpRequest()

        request.META = {

            'SERVER_NAME': 'testserver',

            'SERVER_PORT': 80,

        }

        request.method = method

        request.path = request.path_info = "/cache/%s" % path

        return request
@@ -544,18 +545,76 @@ class CacheUtils(unittest.TestCase): 
        self.assertEqual(get_cache_key(request), None)

        # Set headers to an empty list.

        learn_cache_key(request, response)

        self.assertEqual(get_cache_key(request), 'views.decorators.cache.cache_page.settingsprefix.a8c87a3d8c44853d7f79474f7ffe4ad5.d41d8cd98f00b204e9800998ecf8427e')

        self.assertEqual(get_cache_key(request), 'views.decorators.cache.cache_page.settingsprefix.GET.a8c87a3d8c44853d7f79474f7ffe4ad5.d41d8cd98f00b204e9800998ecf8427e')

        # Verify that a specified key_prefix is taken in to account.

        learn_cache_key(request, response, key_prefix=key_prefix)

        self.assertEqual(get_cache_key(request, key_prefix=key_prefix), 'views.decorators.cache.cache_page.localprefix.a8c87a3d8c44853d7f79474f7ffe4ad5.d41d8cd98f00b204e9800998ecf8427e')

        self.assertEqual(get_cache_key(request, key_prefix=key_prefix), 'views.decorators.cache.cache_page.localprefix.GET.a8c87a3d8c44853d7f79474f7ffe4ad5.d41d8cd98f00b204e9800998ecf8427e')



    def test_learn_cache_key(self):

        request = self._get_request(self.path)

        request = self._get_request(self.path, 'HEAD')

        response = HttpResponse()

        response['Vary'] = 'Pony'

        # Make sure that the Vary header is added to the key hash

        learn_cache_key(request, response)

        self.assertEqual(get_cache_key(request), 'views.decorators.cache.cache_page.settingsprefix.a8c87a3d8c44853d7f79474f7ffe4ad5.d41d8cd98f00b204e9800998ecf8427e')

        self.assertEqual(get_cache_key(request), 'views.decorators.cache.cache_page.settingsprefix.HEAD.a8c87a3d8c44853d7f79474f7ffe4ad5.d41d8cd98f00b204e9800998ecf8427e')



class CacheHEADTest(unittest.TestCase):



    def setUp(self):

        self.orig_cache_middleware_seconds = settings.CACHE_MIDDLEWARE_SECONDS

        self.orig_cache_middleware_key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX

        self.orig_cache_backend = settings.CACHE_BACKEND

        settings.CACHE_MIDDLEWARE_SECONDS = 60

        settings.CACHE_MIDDLEWARE_KEY_PREFIX = 'test'

        settings.CACHE_BACKEND = 'locmem:///'

        self.path = '/cache/test/'



    def tearDown(self):

        settings.CACHE_MIDDLEWARE_SECONDS = self.orig_cache_middleware_seconds

        settings.CACHE_MIDDLEWARE_KEY_PREFIX = self.orig_cache_middleware_key_prefix

        settings.CACHE_BACKEND = self.orig_cache_backend



    def _get_request(self, method):

        request = HttpRequest()

        request.META = {

            'SERVER_NAME': 'testserver',

            'SERVER_PORT': 80,

        }

        request.method = method

        request.path = request.path_info = self.path

        return request



    def _get_request_cache(self, method):

        request = self._get_request(method)

        request._cache_update_cache = True

        return request



    def _set_cache(self, request, msg):

        response = HttpResponse()

        response.content = msg

        return UpdateCacheMiddleware().process_response(request, response)



    def test_head_caches_correctly(self):

        test_content = 'test content'



        request = self._get_request_cache('HEAD')

        self._set_cache(request, test_content)



        request = self._get_request('HEAD')

        get_cache_data = FetchFromCacheMiddleware().process_request(request)

        self.assertNotEqual(get_cache_data, None)

        self.assertEqual(test_content, get_cache_data.content)



    def test_head_with_cached_get(self):

        test_content = 'test content'



        request = self._get_request_cache('GET')

        self._set_cache(request, test_content)



        request = self._get_request('HEAD')

        get_cache_data = FetchFromCacheMiddleware().process_request(request)

        self.assertNotEqual(get_cache_data, None)

        self.assertEqual(test_content, get_cache_data.content)



class CacheI18nTest(unittest.TestCase):