Merge sparsehistogram branch into main

examples/random/main.go

@@ -48,14 +48,22 @@ func NewMetrics(reg prometheus.Registerer, normMean, normDomain float64) *metric
 			},
 			[]string{"service"},
 		),
-		// The same as above, but now as a histogram, and only for the normal
-		// distribution. The buckets are targeted to the parameters of the
-		// normal distribution, with 20 buckets centered on the mean, each
-		// half-sigma wide.
+		// The same as above, but now as a histogram, and only for the
+		// normal distribution. The histogram features both conventional
+		// buckets as well as sparse buckets, the latter needed for the
+		// experimental native histograms (ingested by a Prometheus
+		// server v2.40 with the corresponding feature flag
+		// enabled). The conventional buckets are targeted to the
+		// parameters of the normal distribution, with 20 buckets
+		// centered on the mean, each half-sigma wide. The sparse
+		// buckets are always centered on zero, with a growth factor of
+		// one bucket to the text of (at most) 1.1. (The precise factor
+		// is 2^2^-3 = 1.0905077...)
 		rpcDurationsHistogram: prometheus.NewHistogram(prometheus.HistogramOpts{
-			Name:    "rpc_durations_histogram_seconds",
-			Help:    "RPC latency distributions.",
-			Buckets: prometheus.LinearBuckets(normMean-5*normDomain, .5*normDomain, 20),
+			Name:                        "rpc_durations_histogram_seconds",
+			Help:                        "RPC latency distributions.",
+			Buckets:                     prometheus.LinearBuckets(normMean-5*normDomain, .5*normDomain, 20),
+			NativeHistogramBucketFactor: 1.1,
 		}),
 	}
 	reg.MustRegister(m.rpcDurations)

go.mod

@@ -8,7 +8,7 @@ require (
 	github.com/davecgh/go-spew v1.1.1
 	github.com/golang/protobuf v1.5.2
 	github.com/json-iterator/go v1.1.12
-	github.com/prometheus/client_model v0.2.0
+	github.com/prometheus/client_model v0.3.0
 	github.com/prometheus/common v0.37.0
 	github.com/prometheus/procfs v0.8.0
 	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a

go.sum

@@ -134,8 +134,9 @@ github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f/go.mod h1:qRW
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
-github.com/prometheus/client_model v0.2.0 h1:uq5h0d+GuxiXLJLNABMgp2qUWDPiLvgCzz2dUR+/W/M=
 github.com/prometheus/client_model v0.2.0/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
+github.com/prometheus/client_model v0.3.0 h1:UBgGFHqYdG/TPFD1B1ogZywDqEkwp3fBMvqdiQ7Xew4=
+github.com/prometheus/client_model v0.3.0/go.mod h1:LDGWKZIo7rky3hgvBe+caln+Dr3dPggB5dvjtD7w9+w=
 github.com/prometheus/common v0.37.0 h1:ccBbHCgIiT9uSoFY0vX8H3zsNR5eLt17/RQLUvn8pXE=
 github.com/prometheus/common v0.37.0/go.mod h1:phzohg0JFMnBEFGxTDbfu3QyL5GI8gTQJFhYO5B3mfA=
 github.com/prometheus/procfs v0.8.0 h1:ODq8ZFEaYeCaZOJlZZdJA2AbQR98dSHSM1KW/You5mo=