Rewrite BucketCollector

This was a bit unweildy for what I wanted: in particular, I wanted to assign
each measurement straight into a bucket, rather than storing an intermediate
Counter which didn't do any bucketing at all.

I've replaced it with something that is hopefully a bit easier to use.

(I'm not entirely sure what the difference between a HistogramMetricFamily and
a GaugeHistogramMetricFamily is, but given our counters can go down as well as
up the latter *sounds* more accurate?)

1 files changed, 11 insertions, 8 deletions

diff --git a/tests/storage/test_event_metrics.py b/tests/storage/test_event_metrics.py
index 949846fe33..3957471f3f 100644
--- a/tests/storage/test_event_metrics.py
+++ b/tests/storage/test_event_metrics.py
@@ -52,14 +52,14 @@ class ExtremStatisticsTestCase(HomeserverTestCase):
         self.reactor.advance(60 * 60 * 1000)
         self.pump(1)
 
-        items = set(
+        items = list(
             filter(
                 lambda x: b"synapse_forward_extremities_" in x,
-                generate_latest(REGISTRY).split(b"\n"),
+                generate_latest(REGISTRY, emit_help=False).split(b"\n"),
             )
         )
 
-        expected = {
+        expected = [
             b'synapse_forward_extremities_bucket{le="1.0"} 0.0',
             b'synapse_forward_extremities_bucket{le="2.0"} 2.0',
             b'synapse_forward_extremities_bucket{le="3.0"} 2.0',
@@ -72,9 +72,12 @@ class ExtremStatisticsTestCase(HomeserverTestCase):
             b'synapse_forward_extremities_bucket{le="100.0"} 3.0',
             b'synapse_forward_extremities_bucket{le="200.0"} 3.0',
             b'synapse_forward_extremities_bucket{le="500.0"} 3.0',
-            b'synapse_forward_extremities_bucket{le="+Inf"} 3.0',
-            b"synapse_forward_extremities_count 3.0",
-            b"synapse_forward_extremities_sum 10.0",
-        }
-
+            # per https://docs.google.com/document/d/1KwV0mAXwwbvvifBvDKH_LU1YjyXE_wxCkHNoCGq1GX0/edit#heading=h.wghdjzzh72j9,
+            # "inf" is valid: "this includes variants such as inf"
+            b'synapse_forward_extremities_bucket{le="inf"} 3.0',
+            b"# TYPE synapse_forward_extremities_gcount gauge",
+            b"synapse_forward_extremities_gcount 3.0",
+            b"# TYPE synapse_forward_extremities_gsum gauge",
+            b"synapse_forward_extremities_gsum 10.0",
+        ]
         self.assertEqual(items, expected)