Add type annotations to `synapse.metrics` (#10847)

2 files changed, 9 insertions, 8 deletions

diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index 6a7e534576..67ee4c693b 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -159,7 +159,7 @@ class ExpiringCache(Generic[KT, VT]):
             self[key] = value
             return value
 
-    def _prune_cache(self) -> None:
+    async def _prune_cache(self) -> None:
         if not self._expiry_ms:
             # zero expiry time means don't expire. This should never get called
             # since we have this check in start too.
diff --git a/synapse/util/metrics.py b/synapse/util/metrics.py
index ad775dfc7d..98ee49af6e 100644
--- a/synapse/util/metrics.py
+++ b/synapse/util/metrics.py
@@ -56,8 +56,15 @@ block_db_sched_duration = Counter(
     "synapse_util_metrics_block_db_sched_duration_seconds", "", ["block_name"]
 )
 
+
+# This is dynamically created in InFlightGauge.__init__.
+class _InFlightMetric(Protocol):
+    real_time_max: float
+    real_time_sum: float
+
+
 # Tracks the number of blocks currently active
-in_flight = InFlightGauge(
+in_flight: InFlightGauge[_InFlightMetric] = InFlightGauge(
     "synapse_util_metrics_block_in_flight",
     "",
     labels=["block_name"],
@@ -65,12 +72,6 @@ in_flight = InFlightGauge(
 )
 
 
-# This is dynamically created in InFlightGauge.__init__.
-class _InFlightMetric(Protocol):
-    real_time_max: float
-    real_time_sum: float
-
-
 T = TypeVar("T", bound=Callable[..., Any])