misc: add wcs tenant aware cache (#6735)

debian/settings.py

@@ -68,6 +68,14 @@ MIDDLEWARE_CLASSES = (
     'hobo.middleware.cors.CORSMiddleware',
 ) + MIDDLEWARE_CLASSES
 
+CACHES = {
+    'default': {
+        'BACKEND': 'wcs.cache.WcsTenantCache',
+        # add a real Django cache backend, with its parameters if needed
+        'REAL_BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
+        'LOCATION': '127.0.0.1:11211',
+    }
+}
 
 WCS_LEGACY_CONFIG_FILE = '/etc/wcs/wcs.cfg'
 WCS_EXTRA_MODULES = []

tests/test_misc.py

@@ -22,6 +22,9 @@ from wcs.qommon.http_request import HTTPRequest
 from wcs.qommon.backoffice.listing import pagination_links
 from wcs.qommon.emails import email as send_email, docutils
 
+from django.core.cache import cache
+
+
 from utilities import get_app, create_temporary_pub, clean_temporary_pub
 
 def setup_module(module):
@@ -296,3 +299,7 @@ def test_email_signature_rst(emails):
     assert emails.emails['test']['msg'].get_payload()[1].get_content_type() == 'text/html'
     assert 'Footer\nText' in emails.emails['test']['msg'].get_payload()[0].get_payload()
     assert '>Footer</div>' in emails.emails['test']['msg'].get_payload()[1].get_payload()
+
+def test_cache():
+    cache.set('hello', 'world')
+    assert cache.get('hello') == 'world'

wcs/cache.py

@@ -0,0 +1,53 @@
+# w.c.s. - web application for online forms
+# Copyright (C) 2005-2017  Entr'ouvert
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+from django.core.exceptions import ImproperlyConfigured
+from django.utils.module_loading import import_string
+from django.core.cache.backends.base import InvalidCacheBackendError
+
+from quixote import get_publisher
+
+class TenantBaseCache(object):
+    '''Prepend the tenant application directory to the cache prefix'''
+    def set_key_prefix(self, prefix):
+        self.__key_prefix = prefix
+
+    def get_key_prefix(self):
+        if get_publisher():
+            return '%s_%s' % (get_publisher().app_dir, self.__key_prefix)
+        return self.__key_prefix
+
+    key_prefix = property(get_key_prefix, set_key_prefix)
+
+__DERIVED_CLASSES = {}
+
+
+def WcsTenantCache(host, params, **kwargs):
+    try:
+        backend = params['REAL_BACKEND']
+    except KeyError:
+        raise ImproperlyConfigured('The %s.WcsTenantCache backend needs a REAL_BACKEND parameter' % __name__)
+    try:
+        backend_cls = import_string(backend)
+    except ImportError as e:
+        raise InvalidCacheBackendError("Could not find backend '%s': %s" % (backend, e))
+    derived_cls_name = 'Tenant' + backend_cls.__name__
+    if derived_cls_name not in __DERIVED_CLASSES:
+        # dynamically create a new class with TenantBaseCache
+        # and the original class as parents
+        __DERIVED_CLASSES[derived_cls_name] = type(derived_cls_name,
+                (TenantBaseCache, backend_cls), {})
+    return __DERIVED_CLASSES[derived_cls_name](host, params, **kwargs)

wcs/settings.py

@@ -137,6 +137,15 @@ INSTALLED_APPS = (
     'django.contrib.staticfiles',
 )
 
+CACHES = {
+    'default': {
+        'BACKEND': 'wcs.cache.WcsTenantCache',
+        # add a real Django cache backend, with its parameters if needed
+        'REAL_BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
+        'LOCATION': 'wcs',
+    }
+}
+
 WCS_LEGACY_CONFIG_FILE = None
 
 local_settings_file = os.environ.get('WCS_SETTINGS_FILE',