From 33e2916858c0503a54be1c01e242123dcfb02e21 Mon Sep 17 00:00:00 2001
From: Nick Mills-Barrett <nick@beeper.com>
Date: Wed, 25 May 2022 10:46:05 +0100
Subject: [PATCH] Don't create empty AS txns when the AS is down (#12869)

---
 changelog.d/12869.misc          | 1 +
 synapse/appservice/scheduler.py | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)
 create mode 100644 changelog.d/12869.misc

diff --git a/changelog.d/12869.misc b/changelog.d/12869.misc
new file mode 100644
index 000000000..1d9d1c892
--- /dev/null
+++ b/changelog.d/12869.misc
@@ -0,0 +1 @@
+Don't generate empty AS transactions when the AS is flagged as down. Contributed by Nick @ Beeper.
diff --git a/synapse/appservice/scheduler.py b/synapse/appservice/scheduler.py
index 3b49e6071..de5e5216c 100644
--- a/synapse/appservice/scheduler.py
+++ b/synapse/appservice/scheduler.py
@@ -384,6 +384,11 @@ class _TransactionController:
             device_list_summary: The device list summary to include in the transaction.
         """
         try:
+            service_is_up = await self._is_service_up(service)
+            # Don't create empty txns when in recovery mode (ephemeral events are dropped)
+            if not service_is_up and not events:
+                return
+
             txn = await self.store.create_appservice_txn(
                 service=service,
                 events=events,
@@ -393,7 +398,6 @@ class _TransactionController:
                 unused_fallback_keys=unused_fallback_keys or {},
                 device_list_summary=device_list_summary or DeviceListUpdates(),
             )
-            service_is_up = await self._is_service_up(service)
             if service_is_up:
                 sent = await txn.send(self.as_api)
                 if sent: