Reduce volume of 'Waiting for current token' logs, which were introduced in v1.109.0. (#17428)

Introduced in: #17215

This caused us a minor bit of grief as the volume of logs produced was
much higher than normal

---------

Signed-off-by: Olivier 'reivilibre <oliverw@matrix.org>

changelog.d/17428.bugfix

@@ -0,0 +1 @@
+Reduce volume of 'Waiting for current token' logs, which were introduced in v1.109.0.

synapse/notifier.py

@@ -773,6 +773,7 @@ class Notifier:
         stream_token = await self.event_sources.bound_future_token(stream_token)
 
         start = self.clock.time_msec()
+        logged = False
         while True:
             current_token = self.event_sources.get_current_token()
             if stream_token.is_before_or_eq(current_token):
@@ -783,11 +784,13 @@ class Notifier:
             if now - start > 10_000:
                 return False
 
-            logger.info(
-                "Waiting for current token to reach %s; currently at %s",
-                stream_token,
-                current_token,
-            )
+            if not logged:
+                logger.info(
+                    "Waiting for current token to reach %s; currently at %s",
+                    stream_token,
+                    current_token,
+                )
+                logged = True
 
             # TODO: be better
             await self.clock.sleep(0.5)

synapse/types/__init__.py

@@ -777,6 +777,13 @@ class RoomStreamToken(AbstractMultiWriterStreamToken):
 
         return super().bound_stream_token(max_stream)
 
+    def __str__(self) -> str:
+        instances = ", ".join(f"{k}: {v}" for k, v in sorted(self.instance_map.items()))
+        return (
+            f"RoomStreamToken(stream: {self.stream}, topological: {self.topological}, "
+            f"instances: {{{instances}}})"
+        )
+
 
 @attr.s(frozen=True, slots=True, order=False)
 class MultiWriterStreamToken(AbstractMultiWriterStreamToken):
@@ -873,6 +880,13 @@ class MultiWriterStreamToken(AbstractMultiWriterStreamToken):
 
         return True
 
+    def __str__(self) -> str:
+        instances = ", ".join(f"{k}: {v}" for k, v in sorted(self.instance_map.items()))
+        return (
+            f"MultiWriterStreamToken(stream: {self.stream}, "
+            f"instances: {{{instances}}})"
+        )
+
 
 class StreamKeyType(Enum):
     """Known stream types.
@@ -1131,6 +1145,15 @@ class StreamToken:
 
         return True
 
+    def __str__(self) -> str:
+        return (
+            f"StreamToken(room: {self.room_key}, presence: {self.presence_key}, "
+            f"typing: {self.typing_key}, receipt: {self.receipt_key}, "
+            f"account_data: {self.account_data_key}, push_rules: {self.push_rules_key}, "
+            f"to_device: {self.to_device_key}, device_list: {self.device_list_key}, "
+            f"groups: {self.groups_key}, un_partial_stated_rooms: {self.un_partial_stated_rooms_key})"
+        )
+
 
 StreamToken.START = StreamToken(
     RoomStreamToken(stream=0), 0, 0, MultiWriterStreamToken(stream=0), 0, 0, 0, 0, 0, 0