From 0abb094f1ada9c4a78a11eb06b205c00db826860 Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Date: Thu, 21 Feb 2019 17:51:21 +0000
Subject: [PATCH] bail out early in on_new_receipts if no pushers (#4706)

---
 changelog.d/4706.misc      | 1 +
 synapse/push/pusherpool.py | 8 ++++++++
 2 files changed, 9 insertions(+)
 create mode 100644 changelog.d/4706.misc

diff --git a/changelog.d/4706.misc b/changelog.d/4706.misc
new file mode 100644
index 0000000000..73d1ddcc56
--- /dev/null
+++ b/changelog.d/4706.misc
@@ -0,0 +1 @@
+Avoid some redundant work when processing read receipts
diff --git a/synapse/push/pusherpool.py b/synapse/push/pusherpool.py
index 5a4e73ccd6..b2c92ce683 100644
--- a/synapse/push/pusherpool.py
+++ b/synapse/push/pusherpool.py
@@ -140,6 +140,10 @@ class PusherPool:
 
     @defer.inlineCallbacks
     def on_new_notifications(self, min_stream_id, max_stream_id):
+        if not self.pushers:
+            # nothing to do here.
+            return
+
         try:
             users_affected = yield self.store.get_push_action_users_in_range(
                 min_stream_id, max_stream_id
@@ -155,6 +159,10 @@ class PusherPool:
 
     @defer.inlineCallbacks
     def on_new_receipts(self, min_stream_id, max_stream_id, affected_room_ids):
+        if not self.pushers:
+            # nothing to do here.
+            return
+
         try:
             # Need to subtract 1 from the minimum because the lower bound here
             # is not inclusive