From: Thierry Parmentelat <thierry.parmentelat@inria.fr>
Date: Tue, 31 Mar 2015 13:57:52 +0000 (+0200)
Subject: SessionCache is a cleaner and more robust mechanism for caching material attached... 
X-Git-Tag: myslice-1.3~45^2~3
X-Git-Url: http://git.onelab.eu/?p=myslice.git;a=commitdiff_plain;h=6c38e861f92b75716f40ed9d8f15af824d1ec19c

SessionCache is a cleaner and more robust mechanism for caching material attached to a session across requests
---

diff --git a/localauth/manifoldbackend.py b/localauth/manifoldbackend.py
index 4889d34f..c2899e9d 100644
--- a/localauth/manifoldbackend.py
+++ b/localauth/manifoldbackend.py
@@ -7,6 +7,8 @@ from manifold.core.query        import Query
 
 from myslice.settings import config, logger, DEBUG
 
+from unfold.sessioncache import SessionCache
+
 # Name my backend 'ManifoldBackend'
 class ManifoldBackend:
 
@@ -34,7 +36,8 @@ class ManifoldBackend:
             logger.debug("SESSION : {}".format(session))
             
             # Change to session authentication
-            api.auth = {'AuthMethod': 'session', 'session': session['session']}
+            session_auth = {'AuthMethod': 'session', 'session': session['session']}
+            api.auth = session_auth
             self.api = api
 
             # Get account details
@@ -49,7 +52,8 @@ class ManifoldBackend:
             #logger.info("{} {} <{}> logged in"\
             #    .format(person['config']['first_name'], person['config']['last_name'], person['config']['email']))
 
-            request.session['manifold'] = {'auth': api.auth, 'person': person, 'expires': session['expires']}
+            SessionCache().store_auth(request, session_auth)
+
         except ManifoldException as e:
             logger.error("ManifoldException in Auth Backend: {}".format(e.manifold_result))
         except Exception as e:
diff --git a/manifoldapi/manifoldapi.py b/manifoldapi/manifoldapi.py
index f487cb8d..2edecdd7 100644
--- a/manifoldapi/manifoldapi.py
+++ b/manifoldapi/manifoldapi.py
@@ -7,9 +7,10 @@ from django.contrib import messages
 from django.shortcuts import redirect
 
 from manifold.core.result_value import ResultValue
-
 from manifoldresult import ManifoldResult, ManifoldCode, ManifoldException, truncate_result
 
+from unfold.sessioncache import SessionCache
+
 from myslice.settings import config, logger
 
 class ManifoldAPI:
@@ -45,12 +46,12 @@ class ManifoldAPI:
             start = time.time()
             
             # the message to display
-            auth_message = "<AuthMethod not set in {}>".format(auth) if 'AuthMethod' not in self.auth \
+            auth_message = "<AuthMethod not set in {}>".format(self.auth) if 'AuthMethod' not in self.auth \
                            else "[session]" if self.auth['AuthMethod'] == 'session' \
                            else "user:{}".format(self.auth['Username']) if self.auth['AuthMethod'] == 'password' \
                            else "anonymous" if self.auth['AuthMethod'] == 'anonymous' \
                            else "[???]" + "{}".format(self.auth)
-            end_message = "MANIFOLD {}( {}( {} ) ) with auth={} to {}"\
+            end_message = "MANIFOLD <- {}( {}( {} ) ) with auth={} to {}"\
                           .format(methodName,
                                   args[0]['action'] or '', 
                                   args[0]['object'] or '',
@@ -84,15 +85,14 @@ def _execute_query(request, query, manifold_api_session_auth):
     
     manifold_api = ManifoldAPI(auth = manifold_api_session_auth)
     
-    logger.debug("MANIFOLD QUERY : {}".format(" ".join(str(query).split())))
-    #logger.debug("MANIFOLD DICT : {}".format(query.to_dict()))
+    logger.debug("MANIFOLD -> QUERY : {}".format(" ".join(str(query).split())))
     result = manifold_api.forward(query.to_dict())
     if result['code'] == 2:
         # this is gross; at the very least we need to logout() 
         # but most importantly there is a need to refine that test, since 
         # code==2 does not necessarily mean an expired session
         # XXX only if we know it is the issue
-        del request.session['manifold']
+        SessionCache().end_session(request)
         # Flush django session
         request.session.flush()
         #raise Exception, 'Error running query: {}'.format(result)
@@ -106,14 +106,14 @@ def _execute_query(request, query, manifold_api_session_auth):
     return result['value'] 
 
 def execute_query(request, query):
-    if not 'manifold' in request.session or not 'auth' in request.session['manifold']:
+    
+    manifold_api_session_auth = SessionCache().get_auth(request)
+    if not manifold_api_session_auth:
         request.session.flush()
         #raise Exception, "User not authenticated"
         host = request.get_host()
         return redirect('/')
     
-    manifold_api_session_auth = request.session['manifold']['auth']
-    
     return _execute_query(request, query, manifold_api_session_auth)
 
 def execute_admin_query(request, query):
diff --git a/manifoldapi/manifoldproxy.py b/manifoldapi/manifoldproxy.py
index a42e98d5..5a095bfc 100644
--- a/manifoldapi/manifoldproxy.py
+++ b/manifoldapi/manifoldproxy.py
@@ -12,6 +12,8 @@ from manifoldapi                import ManifoldAPI
 from manifoldresult             import ManifoldException
 from manifold.util.log          import Log
 
+from unfold.sessioncache import SessionCache
+
 from myslice.settings import config, logger
 
 # register activity
@@ -59,9 +61,8 @@ def proxy (request,format):
             admin_user, admin_password = config.manifold_admin_user_password()
             manifold_api_session_auth = {'AuthMethod': 'password', 'Username': admin_user, 'AuthString': admin_password}
         else:
-            if 'manifold' in request.session:
-                manifold_api_session_auth = request.session['manifold']['auth']
-            else:
+            manifold_api_session_auth = SessionCache().get_auth(request)
+            if not manifold_api_session_auth:
                 return HttpResponse (json.dumps({'code':0,'value':[]}), mimetype="application/json")
                 
         if debug_empty and manifold_query.action.lower()=='get':
diff --git a/unfold/page.py b/unfold/page.py
index dbe5a7cb..f8f4eb3b 100644
--- a/unfold/page.py
+++ b/unfold/page.py
@@ -9,7 +9,8 @@ from django.template.loader import render_to_string
 from manifoldapi.metadata import MetaData
 
 from unfold.prelude import Prelude
-
+from unfold.sessioncache import SessionCache
+    
 from myslice.configengine import ConfigEngine
 from myslice.settings import logger
 
@@ -98,24 +99,16 @@ class Page:
     # needs to be called explicitly and only when metadata is actually required
     # in particular user needs to be logged
     def get_metadata (self):
-        # look in session's cache - we don't want to retrieve this for every request
-        session=self.request.session
-
-        if 'manifold' not in session:
-            session['manifold'] = {}
-        manifold = session['manifold']
-
-        # if cached, use it
-        if 'metadata' in manifold and isinstance(manifold['metadata'],MetaData):
+        cached_metadata = SessionCache().get_metadata(self.request)
+        if cached_metadata and isinstance(cached_metadata, MetaData):
             logger.debug("Page.get_metadata: return cached value")
-            return manifold['metadata']
+            return cached_metadata
 
         metadata_auth = {'AuthMethod':'anonymous'}
 
-        metadata=MetaData (metadata_auth)
+        metadata = MetaData (metadata_auth)
         metadata.fetch(self.request)
-        # store it for next time
-        manifold['metadata']=metadata
+        SessionCache().store_metadata(self.request, metadata)
         logger.debug("Page.get_metadata: return new value")
         return metadata
             
diff --git a/unfold/sessioncache.py b/unfold/sessioncache.py
new file mode 100644
index 00000000..aff43c49
--- /dev/null
+++ b/unfold/sessioncache.py
@@ -0,0 +1,129 @@
+import uuid
+
+from manifold.util.singleton import Singleton
+
+from myslice.settings import logger
+
+# the key attached to the session object, where we store
+# the uuid attached to that session in this cache
+cache_key = 'cached_uuid'
+
+class _SessionExtension(object):
+    """
+    This object holds all the data we need to attach to a django session object
+    """
+
+    def __init__(self):
+        self.metadata = None
+        self.auth = None
+
+    def __repr__(self):
+        result = "<SessionExtension"
+        if self.metadata: result += " .metadata"
+        if self.auth:     result += " .auth"
+        result += ">"
+        return result
+
+class SessionCache(dict):
+    """
+    As of django1.7, the session object as attached to a django request
+    gets JSON-serialized instead of pickled
+    This breaks our previous or passing data from request to request across
+    a given session - in particular for metadata and auth/session keys
+    Not that the problem is more with metadata as this is a class instance
+    and JSON cannot handle that
+    So instead we decorate the session object with a UID and retrieve all the rest 
+    from the present - singleton - cache instance
+    """
+
+    __metaclass__ = Singleton
+
+    def get_auth(self, request):
+        """
+        Get the auth previously attached to the request's session, or None
+        """
+        result = self._get(request, 'auth')
+        logger.info('OUT {}'.format(result))
+        return result
+
+    def store_auth(self, request, auth):
+        """
+        Store the auth object attached to this request's session
+        create that extension if needed
+        """
+        logger.info('IN {}'.format(auth))
+        return self._store(request, 'auth', auth)
+
+    def get_metadata(self, request):
+        """
+        retrieve metadata attached to this request's session, or None
+        """
+        return self._get(request, 'metadata')
+
+    def store_metadata(self, request, metadata):
+        """
+        Store the metadata object attached to this request's session
+        create that extension if needed
+        """
+        return self._store(request, 'metadata', metadata)
+
+    def _get(self, request, key):
+        "internal - retrieve key - do not create anything"
+        session = request.session
+        logger.debug("sessioncache._get_{} session={}".format(key, SessionCache._debug_session(session)))
+#        self._debug(request)
+        if cache_key not in session:
+            return None
+        cached_uuid = session[cache_key]
+        if cached_uuid not in self:
+            return None
+        extension = self[cached_uuid]
+        return getattr(extension, key)
+
+    def _store(self, request, key, value):
+        "internal - set key, attach and create extension if needed"
+        session = request.session
+        if cache_key not in session:
+            session[cache_key] = uuid.uuid1().int
+        cached_uuid = session[cache_key]
+        if cached_uuid not in self:
+            self[cached_uuid] = _SessionExtension()
+        extension = self[cached_uuid]
+        setattr(extension, key, value)
+        logger.debug("sessioncache._store_{} session={}".format(key, SessionCache._debug_session(session)))
+#        self._debug(request)
+
+    def end_session(self, request):
+        """
+        Clear all data related to this request's session has we are logging out
+        This is for garbage collection
+        """
+        session = request.session
+        logger.debug("SessionCache.end_session() {}".format(self._debug_session(session)))
+        if cache_key not in session:
+            return
+        cached_uuid = session[cache_key]
+        if cached_uuid in self:
+            del self[cached_uuid]
+
+    def _debug(self, request):
+        session = request.session
+        logger.debug("SessionCache: ---------- with session {}".format(self._debug_session(session)))
+        for k,v in self.iteritems():
+            logger.debug("SessionCache {} -> {}".format(k,v))
+        if cache_key not in session:
+            return
+        cached_uuid = session[cache_key]
+        if cached_uuid not in self:
+            return
+        extension = self[cached_uuid]
+        logger.debug("SessionCache: found extension {}".format(extension))
+        logger.debug("SessionCache: ----------")
+        
+    @staticmethod
+    def _debug_session(session):
+        result = ""
+        result += "{} x {}".format(session, session.keys())
+        if cache_key in session:
+            result += " <{} = {}>".format(cache_key, session[cache_key])
+        return result