From 50f96f256f01dcdb549017f68eccb2ae8a285134 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 29 Apr 2015 19:17:00 +0100
Subject: [PATCH] Also remove yield from within lock in the other generator

---
 synapse/storage/util/id_generators.py | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/synapse/storage/util/id_generators.py b/synapse/storage/util/id_generators.py
index 54aeff2b43..a51268511c 100644
--- a/synapse/storage/util/id_generators.py
+++ b/synapse/storage/util/id_generators.py
@@ -30,15 +30,13 @@ class IdGenerator(object):
 
     @defer.inlineCallbacks
     def get_next(self):
+        if self._next_id is None:
+            yield self.store.runInteraction(
+                "IdGenerator_%s" % (self.table,),
+                self.get_next_txn,
+            )
+
         with self._lock:
-            if not self._next_id:
-                res = yield self.store._execute_and_decode(
-                    "IdGenerator_%s" % (self.table,),
-                    "SELECT MAX(%s) as mx FROM %s" % (self.column, self.table,)
-                )
-
-                self._next_id = (res and res[0] and res[0]["mx"]) or 1
-
             i = self._next_id
             self._next_id += 1
             defer.returnValue(i)