Convert the federation agent and related code to async/await. (#7874)

synapse/http/federation/matrix_federation_agent.py

@@ -15,6 +15,7 @@
 
 import logging
 import urllib
+from typing import List
 
 from netaddr import AddrFormatError, IPAddress
 from zope.interface import implementer
@@ -236,11 +237,10 @@ class MatrixHostnameEndpoint(object):
 
         return run_in_background(self._do_connect, protocol_factory)
 
-    @defer.inlineCallbacks
-    def _do_connect(self, protocol_factory):
+    async def _do_connect(self, protocol_factory):
         first_exception = None
 
-        server_list = yield self._resolve_server()
+        server_list = await self._resolve_server()
 
         for server in server_list:
             host = server.host
@@ -251,7 +251,7 @@ class MatrixHostnameEndpoint(object):
                 endpoint = HostnameEndpoint(self._reactor, host, port)
                 if self._tls_options:
                     endpoint = wrapClientTLS(self._tls_options, endpoint)
-                result = yield make_deferred_yieldable(
+                result = await make_deferred_yieldable(
                     endpoint.connect(protocol_factory)
                 )
 
@@ -271,13 +271,9 @@ class MatrixHostnameEndpoint(object):
         # to try and if that doesn't work then we'll have an exception.
         raise Exception("Failed to resolve server %r" % (self._parsed_uri.netloc,))
 
-    @defer.inlineCallbacks
-    def _resolve_server(self):
+    async def _resolve_server(self) -> List[Server]:
         """Resolves the server name to a list of hosts and ports to attempt to
         connect to.
-
-        Returns:
-            Deferred[list[Server]]
         """
 
         if self._parsed_uri.scheme != b"matrix":
@@ -298,7 +294,7 @@ class MatrixHostnameEndpoint(object):
         if port or _is_ip_literal(host):
             return [Server(host, port or 8448)]
 
-        server_list = yield self._srv_resolver.resolve_service(b"_matrix._tcp." + host)
+        server_list = await self._srv_resolver.resolve_service(b"_matrix._tcp." + host)
 
         if server_list:
             return server_list

synapse/http/federation/srv_resolver.py

@@ -17,10 +17,10 @@
 import logging
 import random
 import time
+from typing import List
 
 import attr
 
-from twisted.internet import defer
 from twisted.internet.error import ConnectError
 from twisted.names import client, dns
 from twisted.names.error import DNSNameError, DomainError
@@ -113,16 +113,14 @@ class SrvResolver(object):
         self._cache = cache
         self._get_time = get_time
 
-    @defer.inlineCallbacks
-    def resolve_service(self, service_name):
+    async def resolve_service(self, service_name: bytes) -> List[Server]:
         """Look up a SRV record
 
         Args:
             service_name (bytes): record to look up
 
         Returns:
-            Deferred[list[Server]]:
-                a list of the SRV records, or an empty list if none found
+            a list of the SRV records, or an empty list if none found
         """
         now = int(self._get_time())
 
@@ -136,7 +134,7 @@ class SrvResolver(object):
                 return _sort_server_list(servers)
 
         try:
-            answers, _, _ = yield make_deferred_yieldable(
+            answers, _, _ = await make_deferred_yieldable(
                 self._dns_client.lookupService(service_name)
             )
         except DNSNameError: