update hints and comment

synapse/http/additional_resource.py

@@ -12,8 +12,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import TYPE_CHECKING
+
+from twisted.web.server import Request
+
 from synapse.http.server import DirectServeJsonResource
 
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
 
 class AdditionalResource(DirectServeJsonResource):
     """Resource wrapper for additional_resources
@@ -25,22 +32,22 @@ class AdditionalResource(DirectServeJsonResource):
     and exception handling.
     """
 
-    def __init__(self, hs, handler):
+    def __init__(self, hs: "HomeServer", handler: Request):
         """Initialise AdditionalResource
 
         The ``handler`` should return a deferred which completes when it has
         done handling the request. It should write a response with
         ``request.write()``, and call ``request.finish()``.
 
         Args:
-            hs (synapse.server.HomeServer): homeserver
-            handler ((twisted.web.server.Request) -> twisted.internet.defer.Deferred):
+            hs: homeserver
+            handler (twisted.internet.defer.Deferred):
                 function to be called to handle the request.
         """
         super().__init__()
         self._handler = handler
 
-    def _async_render(self, request):
+    def _async_render(self, request: Request):
         # Cheekily pass the result straight through, so we don't need to worry
         # if its an awaitable or not.
         return self._handler(request)

synapse/http/federation/srv_resolver.py

@@ -28,10 +28,10 @@
 
 logger = logging.getLogger(__name__)
 
-SERVER_CACHE: Dict = {}
+SERVER_CACHE: Dict[bytes, List[Server]] = {}
 
 
-@attr.s(slots=True, frozen=True)
+@attr.s(auto_attribs=True, slots=True, frozen=True)
 class Server:
     """
     Our record of an individual server which can be tried to reach a destination.
@@ -45,11 +45,11 @@ class Server:
             the epoch
     """
 
-    host: bytes = attr.ib()
-    port: int = attr.ib()
-    priority: int = attr.ib(default=0)
-    weight: int = attr.ib(default=0)
-    expires: int = attr.ib(default=0)
+    host: bytes
+    port: int
+    priority: int = 0
+    weight: int = 0
+    expires: int = 0
 
 
 def _sort_server_list(server_list):
@@ -110,8 +110,8 @@ class SrvResolver:
     def __init__(
         self,
         dns_client=client,
-        cache: Dict = SERVER_CACHE,
-        get_time: Callable = time.time,
+        cache: Dict[bytes, List[Server]] = SERVER_CACHE,
+        get_time: Callable[[], float] = time.time,
     ):
         self._dns_client = dns_client
         self._cache = cache

synapse/http/proxyagent.py

@@ -198,8 +198,7 @@ def request(
                     self.http_proxy_creds.as_proxy_authorization_value(),
                 )
             # Cache *all* connections under the same key, since we are only
-            # connecting to a single destination, the proxy
-            # The URL of proxy is not important for the key
+            # connecting to a single destination, the proxy:
             pool_key = "http-proxy"
             endpoint = self.http_proxy_endpoint
             request_path = uri