From fc6d4974a60a0d47492f5c5c8dff45abbf9abe03 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Mon, 8 May 2017 15:33:57 +0100
Subject: [PATCH] Comment

---
 synapse/storage/devices.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/synapse/storage/devices.py b/synapse/storage/devices.py
index fc87c92182..6727861eb5 100644
--- a/synapse/storage/devices.py
+++ b/synapse/storage/devices.py
@@ -29,6 +29,8 @@ class DeviceStore(SQLBaseStore):
     def __init__(self, hs):
         super(DeviceStore, self).__init__(hs)
 
+        # Map of (user_id, device_id) -> bool. If there is an entry that implies
+        # the device exists.
         self.device_id_exists_cache = Cache(
             name="device_id_exists",
             keylen=2,