Try to express that counts are int, not float

synapse/http/request_metrics.py

@@ -16,7 +16,7 @@
 import logging
 import threading
 import traceback
-from typing import Dict, Set, Tuple
+from typing import Dict, Mapping, Set, Tuple
 
 from prometheus_client.core import Counter, Histogram
 
@@ -113,7 +113,7 @@
 _in_flight_requests_lock = threading.Lock()
 
 
-def _get_in_flight_counts() -> Dict[Tuple[str, ...], float]:
+def _get_in_flight_counts() -> Mapping[Tuple[str, ...], int]:
     """Returns a count of all in flight requests by (method, server_name)"""
     # Cast to a list to prevent it changing while the Prometheus
     # thread is collecting metrics
@@ -126,10 +126,10 @@ def _get_in_flight_counts() -> Dict[Tuple[str, ...], float]:
     # Map from (method, name) -> int, the number of in flight requests of that
     # type. The key type is Tuple[str, str], but we leave the length unspecified
     # for compatability with LaterGauge's annotations.
-    counts: Dict[Tuple[str, ...], float] = {}
+    counts: Dict[Tuple[str, ...], int] = {}
     for rm in reqs:
         key = (rm.method, rm.name)
-        counts[key] = counts.get(key, 0.0) + 1.0
+        counts[key] = counts.get(key, 0) + 1
 
     return counts
 

synapse/metrics/__init__.py

@@ -20,7 +20,7 @@
 import platform
 import threading
 import time
-from typing import Callable, Dict, Iterable, Optional, Tuple, Union
+from typing import Callable, Dict, Iterable, Mapping, Optional, Tuple, Union
 
 import attr
 from prometheus_client import Counter, Gauge, Histogram
@@ -67,7 +67,7 @@ class LaterGauge:
     labels = attr.ib(hash=False, type=Optional[Iterable[str]])
     # 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 = attr.ib(type=Callable[[], Union[Dict[Tuple[str, ...], float], float]])
+    caller = attr.ib(type=Callable[[], Union[Mapping[Tuple[str, ...], float], float]])
 
     def collect(self):
 
@@ -80,11 +80,11 @@ def collect(self):
             yield g
             return
 
-        if isinstance(calls, dict):
+        if isinstance(calls, float):
+            g.add_metric([], calls)
+        else:
             for k, v in calls.items():
                 g.add_metric(k, v)
-        else:
-            g.add_metric([], calls)
 
         yield g