Reduce federation presence replication traffic

This is mainly done by moving the calculation of where to send presence
updates from the presence handler to the transaction queue, so we only
need to send the presence event (and not the destinations) across the
replication connection. Before we were duplicating by sending the full
state across once per destination.

1 files changed, 12 insertions, 0 deletions

diff --git a/synapse/app/federation_sender.py b/synapse/app/federation_sender.py
index 477e16e0fa..49efb602bc 100644
--- a/synapse/app/federation_sender.py
+++ b/synapse/app/federation_sender.py
@@ -32,6 +32,7 @@ from synapse.replication.slave.storage.transactions import TransactionStore
 from synapse.replication.slave.storage.devices import SlavedDeviceStore
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.storage.engines import create_engine
+from synapse.storage.presence import PresenceStore
 from synapse.util.async import Linearizer
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, PreserveLoggingContext, preserve_fn
@@ -80,6 +81,17 @@ class FederationSenderSlaveStore(
 
         return rows[0][0] if rows else -1
 
+    # XXX: This is a bit broken because we don't persist the accepted list in a
+    # way that can be replicated. This means that we don't have a way to
+    # invalidate the cache correctly.
+    # This is fine since in practice nobody uses the presence list stuff...
+    get_presence_list_accepted = PresenceStore.__dict__[
+        "get_presence_list_accepted"
+    ]
+    get_presence_list_observers_accepted = PresenceStore.__dict__[
+        "get_presence_list_observers_accepted"
+    ]
+
 
 class FederationSenderServer(HomeServer):
     def get_db_conn(self, run_new_connection=True):