set self.rset else we're missing some stuff since TheMainTemplate instance as None as rset
"""HTTP cache managers
:organization: Logilab
:copyright: 2001-2008 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
"""
__docformat__ = "restructuredtext en"
from mx.DateTime import DateTimeFromTicks, now, gmtime
# time delta usable to convert localized time to GMT time
GMTOFFSET = - (now() - gmtime())
class NoHTTPCacheManager(object):
"""default cache manager: set no-cache cache control policy"""
def __init__(self, view):
self.view = view
self.req = view.req
self.rset = view.rset
def set_headers(self):
self.req.set_header('Cache-control', 'no-cache')
class MaxAgeHTTPCacheManager(NoHTTPCacheManager):
"""max-age cache manager: set max-age cache control policy, with max-age
specified with the `cache_max_age` attribute of the view
"""
def set_headers(self):
self.req.set_header('Cache-control',
'max-age=%s' % self.view.cache_max_age)
class EtagHTTPCacheManager(NoHTTPCacheManager):
"""etag based cache manager for startup views
* etag is generated using the view name and the user's groups
* set policy to 'must-revalidate' and expires to the current time to force
revalidation on each request
"""
# GMT time required
date_format = "%a, %d %b %Y %H:%M:%S GMT"
def etag(self):
return self.view.id + '/' + ','.join(sorted(self.req.user.groups))
def max_age(self):
# 0 to actually force revalidation
return 0
def last_modified(self):
return self.view.last_modified()
def set_headers(self):
req = self.req
try:
req.set_header('Etag', '"%s"' % self.etag())
except NoEtag:
self.req.set_header('Cache-control', 'no-cache')
return
req.set_header('Cache-control',
'must-revalidate;max-age=%s' % self.max_age())
mdate = self.last_modified()
req.set_header('Last-modified', mdate.strftime(self.date_format))
class EntityHTTPCacheManager(EtagHTTPCacheManager):
"""etag based cache manager for view displaying a single entity
* etag is generated using entity's eid, the view name and the user's groups
* get last modified time from the entity definition (this may not be the
entity's modification time since a view may include some related entities
with a modification time to consider) using the `last_modified` method
"""
def etag(self):
if self.rset is None or len(self.rset) == 0: # entity startup view for instance
return super(EntityHTTPCacheManager, self).etag()
if len(self.rset) > 1:
raise NoEtag()
etag = super(EntityHTTPCacheManager, self).etag()
eid = self.rset[0][0]
if self.req.user.owns(eid):
etag += ',owners'
return str(eid) + '/' + etag
class NoEtag(Exception):
"""an etag can't be generated"""
__all__ = ('GMTOFFSET',
'NoHTTPCacheManager', 'MaxAgeHTTPCacheManager',
'EtagHTTPCacheManager', 'EntityHTTPCacheManager')
# monkey patching, so view doesn't depends on this module and we have all
# http cache related logic here
from cubicweb.common import view
def set_http_cache_headers(self):
self.http_cache_manager(self).set_headers()
view.View.set_http_cache_headers = set_http_cache_headers
def last_modified(self):
"""return the date/time where this view should be considered as
modified. Take care of possible related objects modifications.
/!\ must return GMT time /!\
"""
# XXX check view module's file modification time in dev mod ?
ctime = gmtime()
if self.cache_max_age:
mtime = self.req.header_if_modified_since()
if mtime:
if (ctime - mtime).seconds > self.cache_max_age:
mtime = ctime
else:
mtime = ctime
else:
mtime = ctime
# mtime = ctime will force page rerendering
return mtime
view.View.last_modified = last_modified
# configure default caching
view.View.http_cache_manager = NoHTTPCacheManager
# max-age=0 to actually force revalidation when needed
view.View.cache_max_age = 0
view.EntityView.http_cache_manager = EntityHTTPCacheManager
view.StartupView.http_cache_manager = MaxAgeHTTPCacheManager
view.StartupView.cache_max_age = 60*60*2 # stay in http cache for 2 hours by default