Modify StoreKeyFetcher to read from server_keys_json. (#15417)

Before this change:

* `PerspectivesKeyFetcher` and `ServerKeyFetcher` write to `server_keys_json`.
* `PerspectivesKeyFetcher` also writes to `server_signature_keys`.
* `StoreKeyFetcher` reads from `server_signature_keys`.

After this change:

* `PerspectivesKeyFetcher` and `ServerKeyFetcher` write to `server_keys_json`.
* `PerspectivesKeyFetcher` also writes to `server_signature_keys`.
* `StoreKeyFetcher` reads from `server_keys_json`.

This results in `StoreKeyFetcher` now using the results from `ServerKeyFetcher`
in addition to those from `PerspectivesKeyFetcher`, i.e. keys which are directly
fetched from a server will now be pulled from the database instead of refetched.

An additional minor change is included to avoid creating a `PerspectivesKeyFetcher`
(and checking it) if no `trusted_key_servers` are configured.

The overall impact of this should be better usage of cached results:

* If a server has no trusted key servers configured then it should reduce how often keys
  are fetched.
* if a server's trusted key server does not have a requested server's keys cached then it
  should reduce how often keys are directly fetched.

1 files changed, 8 insertions, 8 deletions

diff --git a/tests/storage/test_keys.py b/tests/storage/test_keys.py
index 5901d80f26..5d7c13e6d0 100644
--- a/tests/storage/test_keys.py
+++ b/tests/storage/test_keys.py
@@ -37,13 +37,13 @@ KEY_2 = decode_verify_key_base64(
 
 
 class KeyStoreTestCase(tests.unittest.HomeserverTestCase):
-    def test_get_server_verify_keys(self) -> None:
+    def test_get_server_signature_keys(self) -> None:
         store = self.hs.get_datastores().main
 
         key_id_1 = "ed25519:key1"
         key_id_2 = "ed25519:KEY_ID_2"
         self.get_success(
-            store.store_server_verify_keys(
+            store.store_server_signature_keys(
                 "from_server",
                 10,
                 {
@@ -54,7 +54,7 @@ class KeyStoreTestCase(tests.unittest.HomeserverTestCase):
         )
 
         res = self.get_success(
-            store.get_server_verify_keys(
+            store.get_server_signature_keys(
                 [
                     ("server1", key_id_1),
                     ("server1", key_id_2),
@@ -87,7 +87,7 @@ class KeyStoreTestCase(tests.unittest.HomeserverTestCase):
         key_id_2 = "ed25519:key2"
 
         self.get_success(
-            store.store_server_verify_keys(
+            store.store_server_signature_keys(
                 "from_server",
                 0,
                 {
@@ -98,7 +98,7 @@ class KeyStoreTestCase(tests.unittest.HomeserverTestCase):
         )
 
         res = self.get_success(
-            store.get_server_verify_keys([("srv1", key_id_1), ("srv1", key_id_2)])
+            store.get_server_signature_keys([("srv1", key_id_1), ("srv1", key_id_2)])
         )
         self.assertEqual(len(res.keys()), 2)
 
@@ -111,20 +111,20 @@ class KeyStoreTestCase(tests.unittest.HomeserverTestCase):
         self.assertEqual(res2.valid_until_ts, 200)
 
         # we should be able to look up the same thing again without a db hit
-        res = self.get_success(store.get_server_verify_keys([("srv1", key_id_1)]))
+        res = self.get_success(store.get_server_signature_keys([("srv1", key_id_1)]))
         self.assertEqual(len(res.keys()), 1)
         self.assertEqual(res[("srv1", key_id_1)].verify_key, KEY_1)
 
         new_key_2 = signedjson.key.get_verify_key(
             signedjson.key.generate_signing_key("key2")
         )
-        d = store.store_server_verify_keys(
+        d = store.store_server_signature_keys(
             "from_server", 10, {("srv1", key_id_2): FetchKeyResult(new_key_2, 300)}
         )
         self.get_success(d)
 
         res = self.get_success(
-            store.get_server_verify_keys([("srv1", key_id_1), ("srv1", key_id_2)])
+            store.get_server_signature_keys([("srv1", key_id_1), ("srv1", key_id_2)])
         )
         self.assertEqual(len(res.keys()), 2)