New Store mechanism to use with Google App Engine

web/session.py

@@ -352,6 +352,45 @@ def cleanup(self, timeout):
             atime, v = self.shelf[k]
             if now - atime > timeout :
                 del self[k]
+
+try:
+    from google.appengine.ext import db
+
+    CLEANUP_BATCH_SIZE = 20
+
+    class WebpySession(db.Model):
+        """Model used to save session data to Google App Engine DB"""
+        data = db.BlobProperty()
+        atime = db.DateTimeProperty(auto_now=True)
+
+    class GoogleStore(Store):
+        """Google Datastore"""
+        def __init__(self, prefix="p"):
+            self.prefix=prefix
+
+        def __contains__(self, key):
+            return WebpySession.get_by_key_name(self.prefix+key) is not None
+
+        def __getitem__(self, key):
+            try:
+                return pickle.loads(WebpySession.get_by_key_name(self.prefix+key).data)
+            except AttributeError:
+                raise KeyError, key
+
+        def __setitem__(self, key, value):
+            r = WebpySession.get_or_insert(self.prefix+key)
+            r.data = pickle.dumps(value)
+            r.put()
+
+        def __delitem__(self, key):
+            try:
+                WebpySession.get_by_key_name(self.prefix+key).delete()
+            except AttributeError:
+                pass
+        def cleanup(self, timeout):
+            db.delete(WebpySession.all().filter('atime <', datetime.datetime.now()-datetime.timedelta(seconds=timeout)).fetch(CLEANUP_BATCH_SIZE))            
+except ImportError:
+    pass                
 
 if __name__ == '__main__' :
     import doctest