Add output to io.Writer, including ioutil.Discard.

writer.go

@@ -0,0 +1,66 @@
+package metrics
+
+import (
+	"fmt"
+	"io"
+	"time"
+)
+
+// Output each metric in the given registry periodically using the given
+// io.Writer.
+func Write(r Registry, d time.Duration, w io.Writer) {
+	for {
+		r.Each(func(name string, i interface{}) {
+			switch m := i.(type) {
+			case Counter:
+				fmt.Fprintf(w, "counter %s\n", name)
+				fmt.Fprintf(w, "  count:       %9d\n", m.Count())
+			case Gauge:
+				fmt.Fprintf(w, "gauge %s\n", name)
+				fmt.Fprintf(w, "  value:       %9d\n", m.Value())
+			case Healthcheck:
+				m.Check()
+				fmt.Fprintf(w, "healthcheck %s\n", name)
+				fmt.Fprintf(w, "  error:       %v\n", m.Error())
+			case Histogram:
+				ps := m.Percentiles([]float64{0.5, 0.75, 0.95, 0.99, 0.999})
+				fmt.Fprintf(w, "histogram %s\n", name)
+				fmt.Fprintf(w, "  count:       %9d\n", m.Count())
+				fmt.Fprintf(w, "  min:         %9d\n", m.Min())
+				fmt.Fprintf(w, "  max:         %9d\n", m.Max())
+				fmt.Fprintf(w, "  mean:        %12.2f\n", m.Mean())
+				fmt.Fprintf(w, "  stddev:      %12.2f\n", m.StdDev())
+				fmt.Fprintf(w, "  median:      %12.2f\n", ps[0])
+				fmt.Fprintf(w, "  75%%:         %12.2f\n", ps[1])
+				fmt.Fprintf(w, "  95%%:         %12.2f\n", ps[2])
+				fmt.Fprintf(w, "  99%%:         %12.2f\n", ps[3])
+				fmt.Fprintf(w, "  99.9%%:       %12.2f\n", ps[4])
+			case Meter:
+				fmt.Fprintf(w, "meter %s\n", name)
+				fmt.Fprintf(w, "  count:       %9d\n", m.Count())
+				fmt.Fprintf(w, "  1-min rate:  %12.2f\n", m.Rate1())
+				fmt.Fprintf(w, "  5-min rate:  %12.2f\n", m.Rate5())
+				fmt.Fprintf(w, "  15-min rate: %12.2f\n", m.Rate15())
+				fmt.Fprintf(w, "  mean rate:   %12.2f\n", m.RateMean())
+			case Timer:
+				ps := m.Percentiles([]float64{0.5, 0.75, 0.95, 0.99, 0.999})
+				fmt.Fprintf(w, "timer %s\n", name)
+				fmt.Fprintf(w, "  count:       %9d\n", m.Count())
+				fmt.Fprintf(w, "  min:         %9d\n", m.Min())
+				fmt.Fprintf(w, "  max:         %9d\n", m.Max())
+				fmt.Fprintf(w, "  mean:        %12.2f\n", m.Mean())
+				fmt.Fprintf(w, "  stddev:      %12.2f\n", m.StdDev())
+				fmt.Fprintf(w, "  median:      %12.2f\n", ps[0])
+				fmt.Fprintf(w, "  75%%:         %12.2f\n", ps[1])
+				fmt.Fprintf(w, "  95%%:         %12.2f\n", ps[2])
+				fmt.Fprintf(w, "  99%%:         %12.2f\n", ps[3])
+				fmt.Fprintf(w, "  99.9%%:       %12.2f\n", ps[4])
+				fmt.Fprintf(w, "  1-min rate:  %12.2f\n", m.Rate1())
+				fmt.Fprintf(w, "  5-min rate:  %12.2f\n", m.Rate5())
+				fmt.Fprintf(w, "  15-min rate: %12.2f\n", m.Rate15())
+				fmt.Fprintf(w, "  mean rate:   %12.2f\n", m.RateMean())
+			}
+		})
+		time.Sleep(d)
+	}
+}