diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
new file mode 100644
index 0000000000..ca15ec09ae
--- /dev/null
+++ b/synapse/events/snapshot.py
@@ -0,0 +1,63 @@
+# -*- coding: utf-8 -*-
+# Copyright 2014 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from twisted.internet import defer
+
+
+class EventSnapshot(object):
+ def __init__(self, prev_events, depth, current_state,
+ current_state_group):
+ self._prev_events = prev_events
+ self._depth = depth
+ self._current_state = current_state
+ self._current_state_group = current_state_group
+
+
+class EventCache(object):
+ def __init__(self, store):
+ self._store = store
+
+ self._cache = {}
+
+ @defer.inlineCallbacks
+ def load_event(self, event_id):
+ event = self._cache.get(event_id, None)
+
+ if not event:
+ event = yield self._store.get_event(
+ event_id,
+ allow_none=True
+ )
+
+ if event:
+ self._cache[event_id] = event
+
+ defer.returnValue(event)
+
+ def load_event_from_cache(self, event_id):
+ return self._cache.get(event_id, None)
+
+ def add_to_cache(self, *events):
+ self._cache.update({
+ event.event_id: event
+ for event in events
+ })
+
+
+class EventContext(object):
+
+ def __init__(self, current_state, auth_events):
+ self.current_state = current_state
+ self.auth_events = auth_events
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