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Fix potential race in _start_key_lookups

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If the verify_request.deferred has already completed, then `remove_deferreds`
will be called immediately. It therefore might resolve the server_to_deferred
deferred while there are still other requests for that server in flight.

To avoid that, we should build the complete list of requests, and *then* add the
callbacks.
This commit is contained in:
Richard van der Hoff 2017-09-20 01:32:42 +01:00
parent afbd773dc6
commit abdefb8a01
1 changed files with 8 additions and 5 deletions
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13
synapse/crypto/keyring.py
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@ -172,7 +172,13 @@ class Keyring(object):
# map from server name to a set of request ids # map from server name to a set of request ids
server_to_request_ids = {} server_to_request_ids = {}
def remove_deferreds(res, server_name, verify_request): for verify_request in verify_requests:
server_name = verify_request.server_name
request_id = id(verify_request)
server_to_request_ids.setdefault(server_name, set()).add(request_id)
def remove_deferreds(res, verify_request):
server_name = verify_request.server_name
request_id = id(verify_request) request_id = id(verify_request)
server_to_request_ids[server_name].discard(request_id) server_to_request_ids[server_name].discard(request_id)
if not server_to_request_ids[server_name]: if not server_to_request_ids[server_name]:
@ -182,11 +188,8 @@ class Keyring(object):
return res return res
for verify_request in verify_requests: for verify_request in verify_requests:
server_name = verify_request.server_name
request_id = id(verify_request)
server_to_request_ids.setdefault(server_name, set()).add(request_id)
verify_request.deferred.addBoth( verify_request.deferred.addBoth(
remove_deferreds, server_name, verify_request, remove_deferreds, verify_request,
) )
@defer.inlineCallbacks @defer.inlineCallbacks