def learn_cache_key(request, response, cache_timeout=None, key_prefix=None):
"""
Learns what headers to take into account for some request path from the
response object. It stores those headers in a global path registry so that
later access to that path will know what headers to take into account
without building the response object itself. The headers are named in the
Vary header of the response, but we want to prevent response generation.
The list of headers to use for cache key generation is stored in the same
cache as the pages themselves. If the cache ages some data out of the
cache, this just means that we have to build the response once to get at
the Vary header and so at the list of headers to use for the cache key.
"""
if key_prefix is None:
key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX
if cache_timeout is None:
cache_timeout = settings.CACHE_MIDDLEWARE_SECONDS
cache_key = _generate_cache_header_key(key_prefix, request)
if response.has_header('Vary'):
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)
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)
def learn_cache_key(request, response, cache_timeout=None, key_prefix=None):
"""
Learns what headers to take into account for some request path from the
response object. It stores those headers in a global path registry so that
later access to that path will know what headers to take into account
without building the response object itself. The headers are named in the
Vary header of the response, but we want to prevent response generation.
The list of headers to use for cache key generation is stored in the same
cache as the pages themselves. If the cache ages some data out of the
cache, this just means that we have to build the response once to get at
the Vary header and so at the list of headers to use for the cache key.
"""
if key_prefix is None:
key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX
if cache_timeout is None:
cache_timeout = settings.CACHE_MIDDLEWARE_SECONDS
cache_key = _generate_cache_header_key(key_prefix, request)
if response.has_header('Vary'):
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)
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)
def render(self, context):
try:
expire_time = self.expire_time_var.resolve(context)
except VariableDoesNotExist:
raise TemplateSyntaxError('"cache" tag got an unknown variable: %r' % self.expire_time_var.var)
try:
expire_time = int(expire_time)
except (ValueError, TypeError):
raise TemplateSyntaxError('"cache" tag got a non-integer timeout value: %r' % expire_time)
# Build a unicode key for this fragment and all vary-on's.
args = md5_constructor(':'.join([urlquote(resolve_variable(var, context)) for var in self.vary_on]))
cache_key = 'template.cache.%s.%s' % (self.fragment_name, args.hexdigest())
value = cache.get(cache_key)
if value is None:
value = self.nodelist.render(context)
cache.set(cache_key, value, expire_time)
return value
def render(self, context):
try:
expire_time = self.expire_time_var.resolve(context)
except VariableDoesNotExist:
raise TemplateSyntaxError('"cache" tag got an unknown variable: %r' % self.expire_time_var.var)
try:
expire_time = int(expire_time)
except (ValueError, TypeError):
raise TemplateSyntaxError('"cache" tag got a non-integer timeout value: %r' % expire_time)
# Build a unicode key for this fragment and all vary-on's.
args = md5_constructor(u':'.join([urlquote(resolve_variable(var, context)) for var in self.vary_on]))
cache_key = 'template.cache.%s.%s' % (self.fragment_name, args.hexdigest())
value = cache.get(cache_key)
if value is None:
value = self.nodelist.render(context)
cache.set(cache_key, value, expire_time)
return value
