Finish implementing RM endpoint

- This change causes a 405 to be sent if "m.read_marker" is set via /account_data
 - This also fixes-up the RM endpoint so that it actually Works.

synapse/handlers/read_marker.py

@@ -18,65 +18,74 @@ from ._base import BaseHandler
 from twisted.internet import defer
 
 from synapse.util.logcontext import PreserveLoggingContext
+from synapse.util.async import Linearizer
 from synapse.types import get_domain_from_id
+from synapse.api.errors import SynapseError
 
 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()
+        self.read_marker_linearizer = Linearizer(name="read_marker")
+        self.notifier = hs.get_notifier()
 
     @defer.inlineCallbacks
     def received_client_read_marker(self, room_id, user_id, event_id):
-        """NEEDS DOC
+        """Updates the read marker for a given user in a given room if the event ID given
+        is ahead in the stream relative to the current read marker.
+
+        This uses a notifier to indicate that account data should be sent down /sync if
+        the read marker has changed.
         """
 
-        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"]
+        with (yield self.read_marker_linearizer.queue(room_id + "_" + user_id)):
+            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,
+            should_update = True
+
+            res = yield self.store._simple_select_one(
                 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 not res:
+                raise SynapseError(404, 'Event does not exist')
 
-            if new_to > existing_to:
-                return False
-            elif new_to == existing_to and new_so >= existing_so:
-                return False
+            if existing_read_marker:
+                new_to = int(res["topological_ordering"])
+                new_so = int(res["stream_ordering"])
 
-        # Update account data
-        content = {
-            "marker": event_id
-        }
-        yield self.store.add_account_data_to_room(
-            user_id, room_id, "m.read_marker", content
-        )
+                # Get ordering for existing read marker
+                res = yield self.store._simple_select_one(
+                    table="events",
+                    retcols=["topological_ordering", "stream_ordering"],
+                    keyvalues={"event_id": existing_read_marker['marker']},
+                    allow_none=True
+                )
+                existing_to = int(res["topological_ordering"]) if res else None
+                existing_so = int(res["stream_ordering"]) if res else None
+
+                # Prevent updating if the existing marker is ahead in the stream
+                if existing_to > new_to:
+                    should_update = False
+                elif existing_to == new_to and existing_so >= new_so:
+                    should_update = False
+
+            if should_update:
+                content = {
+                    "marker": event_id
+                }
+                max_id = yield self.store.add_account_data_to_room(
+                    user_id, room_id, "m.read_marker", content
+                )
+                self.notifier.on_new_event(
+                    "account_data_key", max_id, users=[user_id], rooms=[room_id]
+                )