Use ms buckets (#278)

* us ms buckets

* address comments

Author: phbnf

internal/ct/handlers.go

@@ -93,7 +93,7 @@ func setupMetrics() {
 	reqDuration = mustCreate(meter.Float64Histogram("tesseract.http.request.duration",
 		metric.WithDescription("CT HTTP response duration"),
 		metric.WithUnit("ms"),
-		metric.WithExplicitBucketBoundaries(otel.LatencyHistogramBuckets...)))
+		metric.WithExplicitBucketBoundaries(otel.SubSecondLatencyHistogramBuckets...)))
 }
 
 // entrypoints is a list of entrypoint names as exposed in statistics/logging.

internal/otel/cast.go

@@ -17,8 +17,9 @@ package otel
 import "math"
 
 var (
-	// LatencyHistogramBuckets is a range of millisecond scale bucket boundaries which remain useful at around 1-2 seconds timescale in addition to smaller latencies.
-	LatencyHistogramBuckets = []float64{0, 10, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1200, 1400, 1600, 1800, 2000, 2500, 3000, 4000, 5000, 6000, 8000, 10000}
+	// SubSecondLatencyHistogramBuckets is a range of millisecond scale bucket boundaries which remain useful at around 1-2 seconds timescale in addition to smaller latencies.
+	// We use seconds as units, Open Telemetry's default unit for time.
+	SubSecondLatencyHistogramBuckets = []float64{0, 10e-3, 50e-3, 100e-3, 200e-3, 300e-3, 400e-3, 500e-3, 600e-3, 700e-3, 800e-3, 900e-3, 1000e-3, 1200e-3, 1400e-3, 1600e-3, 1800e-3, 2000e-3, 2500e-3, 3000e-3, 4000e-3, 5000e-3, 6000e-3, 8000e-3, 10000e-3}
 )
 
 // Clamp64 casts a uint64 to an int64, clamping it at MaxInt64 if the value is above.