Initial commit of RM server-side impl

(See https://docs.google.com/document/d/1UWqdS-e1sdwkLDUY0wA4gZyIkRp-ekjsLZ8k6g_Zvso/edit#heading=h.lndohpg8at5u)

synapse/handlers/read_marker.py

@@ -0,0 +1,82 @@
+# -*- coding: utf-8 -*-
+# Copyright 2015, 2016 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 ._base import BaseHandler
+
+from twisted.internet import defer
+
+from synapse.util.logcontext import PreserveLoggingContext
+from synapse.types import get_domain_from_id
+
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
+class ReadMarkerHandler(BaseHandler):
+    def __init__(self, hs):
+        super(ReadMarkerHandler, self).__init__(hs)
+
+        self.server_name = hs.config.server_name
+        self.store = hs.get_datastore()
+
+    @defer.inlineCallbacks
+    def received_client_read_marker(self, room_id, user_id, event_id):
+        """NEEDS DOC
+        """
+
+        room_id = read_marker["room_id"]
+        user_id = read_marker["user_id"]
+        event_id = read_marker["event_id"]
+
+        # Get ordering for existing read marker
+        account_data = yield self.store.get_account_data_for_room(user_id, room_id)
+        existing_read_marker = account_data["m.read_marker"]
+
+        if existing_read_marker:
+            # Get ordering for new read marker
+            res = self.store._simple_select_one_txn(
+                txn,
+                table="events",
+                retcols=["topological_ordering", "stream_ordering"],
+                keyvalues={"event_id": event_id},
+                allow_none=True
+            )
+            new_to = int(res["topological_ordering"]) if res else None
+            new_so = int(res["stream_ordering"]) if res else None
+
+            res = self.store._simple_select_one_txn(
+                txn,
+                table="events",
+                retcols=["topological_ordering", "stream_ordering"],
+                keyvalues={"event_id": existing_read_marker.content.marker},
+                allow_none=True
+            )
+            existing_to = int(res["topological_ordering"]) if res else None
+            existing_so = int(res["stream_ordering"]) if res else None
+
+            if new_to > existing_to:
+                return False
+            elif new_to == existing_to and new_so >= existing_so:
+                return False
+
+        # Update account data
+        content = {
+            "marker": event_id
+        }
+        yield self.store.add_account_data_to_room(
+            user_id, room_id, "m.read_marker", content
+        )