Update type annotations for compatiblity with prometheus_client 0.14 (#12389)

Principally, `prometheus_client.REGISTRY.register` now requires its argument to
extend `prometheus_client.Collector`.

Additionally, `Gauge.set` is now annotated so that passing `Optional[int]`
causes an error.

1 files changed, 9 insertions, 7 deletions

diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index d321946aa2..fffd83546c 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -1,4 +1,5 @@
 # Copyright 2015, 2016 OpenMarket Ltd
+# Copyright 2022 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -52,12 +53,13 @@ from synapse.metrics._exposition import (
     start_http_server,
 )
 from synapse.metrics._gc import MIN_TIME_BETWEEN_GCS, install_gc_manager
+from synapse.metrics._types import Collector
 
 logger = logging.getLogger(__name__)
 
 METRICS_PREFIX = "/_synapse/metrics"
 
-all_gauges: "Dict[str, Union[LaterGauge, InFlightGauge]]" = {}
+all_gauges: Dict[str, Collector] = {}
 
 HAVE_PROC_SELF_STAT = os.path.exists("/proc/self/stat")
 
@@ -78,11 +80,10 @@ RegistryProxy = cast(CollectorRegistry, _RegistryProxy)
 
 
 @attr.s(slots=True, hash=True, auto_attribs=True)
-class LaterGauge:
-
+class LaterGauge(Collector):
     name: str
     desc: str
-    labels: Optional[Iterable[str]] = attr.ib(hash=False)
+    labels: Optional[Sequence[str]] = attr.ib(hash=False)
     # callback: should either return a value (if there are no labels for this metric),
     # or dict mapping from a label tuple to a value
     caller: Callable[
@@ -125,7 +126,7 @@ class LaterGauge:
 MetricsEntry = TypeVar("MetricsEntry")
 
 
-class InFlightGauge(Generic[MetricsEntry]):
+class InFlightGauge(Generic[MetricsEntry], Collector):
     """Tracks number of things (e.g. requests, Measure blocks, etc) in flight
     at any given time.
 
@@ -246,7 +247,7 @@ class InFlightGauge(Generic[MetricsEntry]):
         all_gauges[self.name] = self
 
 
-class GaugeBucketCollector:
+class GaugeBucketCollector(Collector):
     """Like a Histogram, but the buckets are Gauges which are updated atomically.
 
     The data is updated by calling `update_data` with an iterable of measurements.
@@ -340,7 +341,7 @@ class GaugeBucketCollector:
 #
 
 
-class CPUMetrics:
+class CPUMetrics(Collector):
     def __init__(self) -> None:
         ticks_per_sec = 100
         try:
@@ -470,6 +471,7 @@ def register_threadpool(name: str, threadpool: ThreadPool) -> None:
 
 
 __all__ = [
+    "Collector",
     "MetricsResource",
     "generate_latest",
     "start_http_server",