Disallow sending of multiple backlog messages in parallel.

matrix/commands.py

@@ -108,6 +108,10 @@ def hook_commands():
 
 def matrix_fetch_old_messages(server, room_id):
     room = server.rooms[room_id]
+
+    if room.backlog_pending:
+        return
+
     prev_batch = room.prev_batch
 
     if not prev_batch:
@@ -119,6 +123,7 @@ def matrix_fetch_old_messages(server, room_id):
         token=prev_batch,
         limit=OPTIONS.backlog_limit
     )
+    room.backlog_pending = True
 
     server.send_or_queue(message)
 

matrix/events.py

@@ -343,6 +343,7 @@ class MatrixBacklogEvent(MatrixEvent):
             message.prnt(room, buf, tags)
 
         room.prev_batch = self.end_token
+        room.backlog_pending = False
 
 
 class MatrixSyncEvent(MatrixEvent):

matrix/rooms.py

@@ -33,6 +33,7 @@ class MatrixRoom:
         self.prev_batch = ""          # type: str
         self.users = dict()           # type: Dict[str, MatrixUser]
         self.encrypted = False        # type: bool
+        self.backlog_pending = False  # type: bool
         # yapf: enable