From 3545e17f43a42273c60f8607ab9e9d56ff1946cd Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Fri, 10 Mar 2017 10:30:38 +0000
Subject: [PATCH] Add setdefault key to ExpiringCache

---
 synapse/util/caches/expiringcache.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index 2987c38a2d..cbdde34a57 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -100,6 +100,13 @@ class ExpiringCache(object):
         except KeyError:
             return default
 
+    def setdefault(self, key, value):
+        try:
+            return self[key]
+        except KeyError:
+            self[key] = value
+            return value
+
     def _prune_cache(self):
         if not self._expiry_ms:
             # zero expiry time means don't expire. This should never get called