reraise exceptions more carefully

We need to be careful (under python 2, at least) that when we reraise an
exception after doing some error handling, we actually reraise the original
exception rather than anything that might have been raised (and handled) during
the error handling.

1 files changed, 10 insertions, 6 deletions

diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index ae7e0d6da2..260df025f9 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -19,9 +19,11 @@
 import httplib
 import itertools
 import logging
+import sys
 
 from signedjson.key import decode_verify_key_bytes
 from signedjson.sign import verify_signed_json
+import six
 from twisted.internet import defer
 from unpaddedbase64 import decode_base64
 
@@ -1513,12 +1515,14 @@ class FederationHandler(BaseHandler):
                 backfilled=backfilled,
             )
         except:  # noqa: E722, as we reraise the exception this is fine.
-            # Ensure that we actually remove the entries in the push actions
-            # staging area
-            logcontext.preserve_fn(
-                self.store.remove_push_actions_from_staging
-            )(event.event_id)
-            raise
+            tp, value, tb = sys.exc_info()
+
+            logcontext.run_in_background(
+                self.store.remove_push_actions_from_staging,
+                event.event_id,
+            )
+
+            six.reraise(tp, value, tb)
 
         if not backfilled:
             # this intentionally does not yield: we don't care about the result