metrics: split gaugeinfo into read/write

metrics/exp/exp.go

@@ -127,7 +127,7 @@ func (exp *exp) publishGaugeFloat64(name string, metric metrics.GaugeFloat64Snap
 	exp.getFloat(name).Set(metric.Value())
 }
 
-func (exp *exp) publishGaugeInfo(name string, metric metrics.GaugeInfo) {
+func (exp *exp) publishGaugeInfo(name string, metric metrics.GaugeInfoSnapshot) {
 	exp.getInfo(name).Set(metric.Value().String())
 }
 
@@ -197,7 +197,7 @@ func (exp *exp) syncToExpvar() {
 		case metrics.GaugeFloat64:
 			exp.publishGaugeFloat64(name, i.Snapshot())
 		case metrics.GaugeInfo:
-			exp.publishGaugeInfo(name, i)
+			exp.publishGaugeInfo(name, i.Snapshot())
 		case metrics.Histogram:
 			exp.publishHistogram(name, i)
 		case metrics.Meter:

metrics/gauge_info.go

@@ -5,14 +5,17 @@ import (
 	"sync"
 )
 
+type GaugeInfoSnapshot interface {
+	Value() GaugeInfoValue
+}
+
 // GaugeInfos hold a GaugeInfoValue value that can be set arbitrarily.
 type GaugeInfo interface {
-	Snapshot() GaugeInfo
 	Update(GaugeInfoValue)
-	Value() GaugeInfoValue
+	Snapshot() GaugeInfoSnapshot
 }
 
-// GaugeInfoValue is a mappng of (string) keys to (string) values
+// GaugeInfoValue is a mapping of keys to values
 type GaugeInfoValue map[string]string
 
 func (val GaugeInfoValue) String() string {
@@ -49,49 +52,17 @@ func NewRegisteredGaugeInfo(name string, r Registry) GaugeInfo {
 	return c
 }
 
-// NewFunctionalGauge constructs a new FunctionalGauge.
-func NewFunctionalGaugeInfo(f func() GaugeInfoValue) GaugeInfo {
-	if !Enabled {
-		return NilGaugeInfo{}
-	}
-	return &FunctionalGaugeInfo{value: f}
-}
-
-// NewRegisteredFunctionalGauge constructs and registers a new StandardGauge.
-func NewRegisteredFunctionalGaugeInfo(name string, r Registry, f func() GaugeInfoValue) GaugeInfo {
-	c := NewFunctionalGaugeInfo(f)
-	if nil == r {
-		r = DefaultRegistry
-	}
-	r.Register(name, c)
-	return c
-}
-
-// GaugeInfoSnapshot is a read-only copy of another GaugeInfo.
-type GaugeInfoSnapshot GaugeInfoValue
-
-// Snapshot returns the snapshot.
-func (g GaugeInfoSnapshot) Snapshot() GaugeInfo { return g }
-
-// Update panics.
-func (GaugeInfoSnapshot) Update(GaugeInfoValue) {
-	panic("Update called on a GaugeInfoSnapshot")
-}
+// gaugeInfoSnapshot is a read-only copy of another GaugeInfo.
+type gaugeInfoSnapshot GaugeInfoValue
 
 // Value returns the value at the time the snapshot was taken.
-func (g GaugeInfoSnapshot) Value() GaugeInfoValue { return GaugeInfoValue(g) }
+func (g gaugeInfoSnapshot) Value() GaugeInfoValue { return GaugeInfoValue(g) }
 
-// NilGauge is a no-op Gauge.
 type NilGaugeInfo struct{}
 
-// Snapshot is a no-op.
-func (NilGaugeInfo) Snapshot() GaugeInfo { return NilGaugeInfo{} }
-
-// Update is a no-op.
-func (NilGaugeInfo) Update(v GaugeInfoValue) {}
-
-// Value is a no-op.
-func (NilGaugeInfo) Value() GaugeInfoValue { return GaugeInfoValue{} }
+func (NilGaugeInfo) Snapshot() GaugeInfoSnapshot { return NilGaugeInfo{} }
+func (NilGaugeInfo) Update(v GaugeInfoValue)     {}
+func (NilGaugeInfo) Value() GaugeInfoValue       { return GaugeInfoValue{} }
 
 // StandardGaugeInfo is the standard implementation of a GaugeInfo and uses
 // sync.Mutex to manage a single string value.
@@ -101,8 +72,8 @@ type StandardGaugeInfo struct {
 }
 
 // Snapshot returns a read-only copy of the gauge.
-func (g *StandardGaugeInfo) Snapshot() GaugeInfo {
-	return GaugeInfoSnapshot(g.Value())
+func (g *StandardGaugeInfo) Snapshot() GaugeInfoSnapshot {
+	return gaugeInfoSnapshot(g.value)
 }
 
 // Update updates the gauge's value.
@@ -111,34 +82,3 @@ func (g *StandardGaugeInfo) Update(v GaugeInfoValue) {
 	defer g.mutex.Unlock()
 	g.value = v
 }
-
-// Value returns the gauge's current value.
-func (g *StandardGaugeInfo) Value() GaugeInfoValue {
-	g.mutex.Lock()
-	defer g.mutex.Unlock()
-	return g.value
-}
-
-// FunctionalGaugeInfo returns value from given function
-type FunctionalGaugeInfo struct {
-	value func() GaugeInfoValue
-}
-
-// Value returns the gauge's current value.
-func (g FunctionalGaugeInfo) Value() GaugeInfoValue {
-	return g.value()
-}
-
-// Value returns the gauge's current value in JSON string format
-func (g FunctionalGaugeInfo) ValueJsonString() string {
-	data, _ := json.Marshal(g.value())
-	return string(data)
-}
-
-// Snapshot returns the snapshot.
-func (g FunctionalGaugeInfo) Snapshot() GaugeInfo { return GaugeInfoSnapshot(g.Value()) }
-
-// Update panics.
-func (FunctionalGaugeInfo) Update(GaugeInfoValue) {
-	panic("Update called on a FunctionalGaugeInfo")
-}

metrics/gauge_info_test.go

@@ -1,7 +1,6 @@
 package metrics
 
 import (
-	"strconv"
 	"testing"
 )
 
@@ -14,62 +13,25 @@ func TestGaugeInfoJsonString(t *testing.T) {
 	},
 	)
 	want := `{"anotherKey":"any_string_value","chain_id":"5","third_key":"anything"}`
-	if have := g.Value().String(); have != want {
-		t.Errorf("\nhave: %v\nwant: %v\n", have, want)
-	}
-}
 
-func TestGaugeInfoSnapshot(t *testing.T) {
-	g := NewGaugeInfo()
-	g.Update(GaugeInfoValue{"value": "original"})
-	snapshot := g.Snapshot() // Snapshot @chainid 5
+	original := g.Snapshot()
 	g.Update(GaugeInfoValue{"value": "updated"})
-	// The 'g' should be updated
-	if have, want := g.Value().String(), `{"value":"updated"}`; have != want {
+
+	if have := original.Value().String(); have != want {
 		t.Errorf("\nhave: %v\nwant: %v\n", have, want)
 	}
-	// Snapshot should be unupdated
-	if have, want := snapshot.Value().String(), `{"value":"original"}`; have != want {
+	if have, want := g.Snapshot().Value().String(), `{"value":"updated"}`; have != want {
 		t.Errorf("\nhave: %v\nwant: %v\n", have, want)
 	}
+
 }
 
 func TestGetOrRegisterGaugeInfo(t *testing.T) {
 	r := NewRegistry()
 	NewRegisteredGaugeInfo("foo", r).Update(
 		GaugeInfoValue{"chain_id": "5"})
-	g := GetOrRegisterGaugeInfo("foo", r)
+	g := GetOrRegisterGaugeInfo("foo", r).Snapshot()
 	if have, want := g.Value().String(), `{"chain_id":"5"}`; have != want {
 		t.Errorf("have\n%v\nwant\n%v\n", have, want)
 	}
 }
-
-func TestFunctionalGaugeInfo(t *testing.T) {
-	info := GaugeInfoValue{"chain_id": "0"}
-	counter := 1
-	// A "functional" gauge invokes the method to obtain the value
-	fg := NewFunctionalGaugeInfo(func() GaugeInfoValue {
-		info["chain_id"] = strconv.Itoa(counter)
-		counter++
-		return info
-	})
-	fg.Value()
-	fg.Value()
-	if have, want := info["chain_id"], "2"; have != want {
-		t.Errorf("have %v want %v", have, want)
-	}
-}
-
-func TestGetOrRegisterFunctionalGaugeInfo(t *testing.T) {
-	r := NewRegistry()
-	NewRegisteredFunctionalGaugeInfo("foo", r, func() GaugeInfoValue {
-		return GaugeInfoValue{
-			"chain_id": "5",
-		}
-	})
-	want := `{"chain_id":"5"}`
-	have := GetOrRegisterGaugeInfo("foo", r).Value().String()
-	if have != want {
-		t.Errorf("have\n%v\nwant\n%v\n", have, want)
-	}
-}

metrics/graphite.go

@@ -74,7 +74,7 @@ func graphite(c *GraphiteConfig) error {
 		case GaugeFloat64:
 			fmt.Fprintf(w, "%s.%s.value %f %d\n", c.Prefix, name, metric.Snapshot().Value(), now)
 		case GaugeInfo:
-			fmt.Fprintf(w, "%s.%s.value %s %d\n", c.Prefix, name, metric.Value().String(), now)
+			fmt.Fprintf(w, "%s.%s.value %s %d\n", c.Prefix, name, metric.Snapshot().Value().String(), now)
 		case Histogram:
 			h := metric.Snapshot()
 			ps := h.Percentiles(c.Percentiles)

metrics/log.go

@@ -35,7 +35,7 @@ func LogScaled(r Registry, freq time.Duration, scale time.Duration, l Logger) {
 				l.Printf("  value:       %f\n", metric.Snapshot().Value())
 			case GaugeInfo:
 				l.Printf("gauge %s\n", name)
-				l.Printf("  value:       %s\n", metric.Value())
+				l.Printf("  value:       %s\n", metric.Snapshot().Value())
 			case Healthcheck:
 				metric.Check()
 				l.Printf("healthcheck %s\n", name)

metrics/opentsdb.go

@@ -73,7 +73,7 @@ func (c *OpenTSDBConfig) writeRegistry(w io.Writer, now int64, shortHostname str
 		case GaugeFloat64:
 			fmt.Fprintf(w, "put %s.%s.value %d %f host=%s\n", c.Prefix, name, now, metric.Snapshot().Value(), shortHostname)
 		case GaugeInfo:
-			fmt.Fprintf(w, "put %s.%s.value %d %s host=%s\n", c.Prefix, name, now, metric.Value().String(), shortHostname)
+			fmt.Fprintf(w, "put %s.%s.value %d %s host=%s\n", c.Prefix, name, now, metric.Snapshot().Value().String(), shortHostname)
 		case Histogram:
 			h := metric.Snapshot()
 			ps := h.Percentiles([]float64{0.5, 0.75, 0.95, 0.99, 0.999})

metrics/prometheus/collector.go

@@ -91,7 +91,7 @@ func (c *collector) addGaugeFloat64(name string, m metrics.GaugeFloat64Snapshot)
 	c.writeGaugeCounter(name, m.Value())
 }
 
-func (c *collector) addGaugeInfo(name string, m metrics.GaugeInfo) {
+func (c *collector) addGaugeInfo(name string, m metrics.GaugeInfoSnapshot) {
 	c.writeGaugeInfo(name, m.Value())
 }
 

metrics/syslog.go

@@ -24,7 +24,7 @@ func Syslog(r Registry, d time.Duration, w *syslog.Writer) {
 			case GaugeFloat64:
 				w.Info(fmt.Sprintf("gauge %s: value: %f", name, metric.Snapshot().Value()))
 			case GaugeInfo:
-				w.Info(fmt.Sprintf("gauge %s: value: %s", name, metric.Value()))
+				w.Info(fmt.Sprintf("gauge %s: value: %s", name, metric.Snapshot().Value()))
 			case Healthcheck:
 				metric.Check()
 				w.Info(fmt.Sprintf("healthcheck %s: error: %v", name, metric.Error()))

metrics/writer.go

@@ -41,7 +41,7 @@ func WriteOnce(r Registry, w io.Writer) {
 			fmt.Fprintf(w, "  value:       %f\n", metric.Snapshot().Value())
 		case GaugeInfo:
 			fmt.Fprintf(w, "gauge %s\n", namedMetric.name)
-			fmt.Fprintf(w, "  value:       %s\n", metric.Value().String())
+			fmt.Fprintf(w, "  value:       %s\n", metric.Snapshot().Value().String())
 		case Healthcheck:
 			metric.Check()
 			fmt.Fprintf(w, "healthcheck %s\n", namedMetric.name)