Pull inner function out.

synapse/crypto/keyring.py

@@ -101,8 +101,23 @@ class Keyring(object):
             defer.returnValue(cached[0])
             return
 
+        download = self.key_downloads.get(server_name)
+
+        if download is None:
+            download = self._get_server_verify_key_impl(server_name, key_ids)
+            self.key_downloads[server_name] = download
+
+            @download.addBoth
+            def callback(ret):
+                del self.key_downloads[server_name]
+                return ret
+
+        r = yield create_observer(download)
+        defer.returnValue(r)
+
+
     @defer.inlineCallbacks
-        def fetch_keys():
+    def _get_server_verify_key_impl(self, server_name, key_ids):
         # Try to fetch the key from the remote server.
 
         limiter = yield get_retry_limiter(
@@ -176,17 +191,3 @@ class Keyring(object):
                 return
 
         raise ValueError("No verification key found for given key ids")
-
-        download = self.key_downloads.get(server_name)
-
-        if download is None:
-            download = fetch_keys()
-            self.key_downloads[server_name] = download
-
-            @download.addBoth
-            def callback(ret):
-                del self.key_downloads[server_name]
-                return ret
-
-        r = yield create_observer(download)
-        defer.returnValue(r)