From 89e786bd85331b73204294e6066dc538f1c9869c Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Mon, 15 Aug 2016 13:45:26 +0100
Subject: [PATCH] Doc get_next() context manager usage
---
synapse/storage/_base.py | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index c55776994d..b0923a9cad 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -873,6 +873,10 @@ class SQLBaseStore(object):
txn.call_after(cache_func.invalidate, keys)
if isinstance(self.database_engine, PostgresEngine):
+ # get_next() returns a context manager which is designed to wrap
+ # the transaction. However, we want to only get an ID when we want
+ # to use it, here, so we need to call __enter__ manually, and have
+ # __exit__ called after the transaction finishes.
ctx = self._cache_id_gen.get_next()
stream_id = ctx.__enter__()
txn.call_after(ctx.__exit__, None, None, None)
--
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