Added unit annotation supports onto tsmon in go.

common/tsmon/metric/metric.go

Index: common/tsmon/metric/metric.go
diff --git a/common/tsmon/metric/metric.go b/common/tsmon/metric/metric.go
index 31cb9774e2d285092f4f3a9054a3da922cb079b9..ad19c80f7b51fda2dc7a3a25c46ba400f4ed09d7 100644
--- a/common/tsmon/metric/metric.go
+++ b/common/tsmon/metric/metric.go
@@ -137,30 +137,33 @@ type CallbackDistribution interface {
 
 // NewInt returns a new non-cumulative integer gauge metric.  This will panic if
 // another metric already exists with this name.
-func NewInt(name string, description string, fields ...field.Field) Int {
-	return NewIntIn(context.Background(), name, description, fields...)
+func NewInt(name string, description string, metadata types.MetricMetadata, fields ...field.Field) Int {
+	return NewIntIn(context.Background(), name, description, metadata, fields...)
 }
 
 // NewIntIn is like NewInt but registers in a given context.
-func NewIntIn(c context.Context, name string, description string, fields ...field.Field) Int {
-	m := &intMetric{metric{MetricInfo: types.MetricInfo{
-		Name:        name,
-		Description: description,
-		Fields:      fields,
-		ValueType:   types.NonCumulativeIntType,
-	}}}
+func NewIntIn(c context.Context, name string, description string, metadata types.MetricMetadata, fields ...field.Field) Int {
+	m := &intMetric{metric{
+		MetricInfo: types.MetricInfo{
+			Name:        name,
+			Description: description,
+			Fields:      fields,
+			ValueType:   types.NonCumulativeIntType,
+		},
+		MetricMetadata: metadata,
+	}}
 	tsmon.Register(c, m)
 	return m
 }
 
 // NewCounter returns a new cumulative integer metric.  This will panic if
 // another metric already exists with this name.
-func NewCounter(name string, description string, fields ...field.Field) Counter {
-	return NewCounterIn(context.Background(), name, description, fields...)
+func NewCounter(name string, description string, metadata types.MetricMetadata, fields ...field.Field) Counter {
+	return NewCounterIn(context.Background(), name, description, metadata, fields...)
 }
 
 // NewCounterIn is like NewCounter but registers in a given context.
-func NewCounterIn(c context.Context, name string, description string, fields ...field.Field) Counter {
+func NewCounterIn(c context.Context, name string, description string, metadata types.MetricMetadata, fields ...field.Field) Counter {
 	m := &counter{intMetric{metric{MetricInfo: types.MetricInfo{
 		Name:        name,
 		Description: description,
@@ -173,12 +176,12 @@ func NewCounterIn(c context.Context, name string, description string, fields ...
 
 // NewFloat returns a new non-cumulative floating-point gauge metric.  This will
 // panic if another metric already exists with this name.
-func NewFloat(name string, description string, fields ...field.Field) Float {
-	return NewFloatIn(context.Background(), name, description, fields...)
+func NewFloat(name string, description string, metadata types.MetricMetadata, fields ...field.Field) Float {
+	return NewFloatIn(context.Background(), name, description, metadata, fields...)
 }
 
 // NewFloatIn is like NewFloat but registers in a given context.
-func NewFloatIn(c context.Context, name string, description string, fields ...field.Field) Float {
+func NewFloatIn(c context.Context, name string, description string, metadata types.MetricMetadata, fields ...field.Field) Float {
 	m := &floatMetric{metric{MetricInfo: types.MetricInfo{
 		Name:        name,
 		Description: description,
@@ -191,12 +194,12 @@ func NewFloatIn(c context.Context, name string, description string, fields ...fi
 
 // NewFloatCounter returns a new cumulative floating-point metric.  This will
 // panic if another metric already exists with this name.
-func NewFloatCounter(name string, description string, fields ...field.Field) FloatCounter {
-	return NewFloatCounterIn(context.Background(), name, description, fields...)
+func NewFloatCounter(name string, description string, metadata types.MetricMetadata, fields ...field.Field) FloatCounter {
+	return NewFloatCounterIn(context.Background(), name, description, metadata, fields...)
 }
 
 // NewFloatCounterIn is like NewFloatCounter but registers in a given context.
-func NewFloatCounterIn(c context.Context, name string, description string, fields ...field.Field) FloatCounter {
+func NewFloatCounterIn(c context.Context, name string, description string, metadata types.MetricMetadata, fields ...field.Field) FloatCounter {
 	m := &floatCounter{floatMetric{metric{MetricInfo: types.MetricInfo{
 		Name:        name,
 		Description: description,
@@ -209,12 +212,12 @@ func NewFloatCounterIn(c context.Context, name string, description string, field
 
 // NewString returns a new string-valued metric.  This will panic if another
 // metric already exists with this name.
-func NewString(name string, description string, fields ...field.Field) String {
-	return NewStringIn(context.Background(), name, description, fields...)
+func NewString(name string, description string, metadata types.MetricMetadata, fields ...field.Field) String {
+	return NewStringIn(context.Background(), name, description, metadata, fields...)
 }
 
 // NewStringIn is like NewString but registers in a given context.
-func NewStringIn(c context.Context, name string, description string, fields ...field.Field) String {
+func NewStringIn(c context.Context, name string, description string, metadata types.MetricMetadata, fields ...field.Field) String {
 	m := &stringMetric{metric{MetricInfo: types.MetricInfo{
 		Name:        name,
 		Description: description,
@@ -227,12 +230,12 @@ func NewStringIn(c context.Context, name string, description string, fields ...f
 
 // NewBool returns a new bool-valued metric.  This will panic if another
 // metric already exists with this name.
-func NewBool(name string, description string, fields ...field.Field) Bool {
-	return NewBoolIn(context.Background(), name, description, fields...)
+func NewBool(name string, description string, metadata types.MetricMetadata, fields ...field.Field) Bool {
+	return NewBoolIn(context.Background(), name, description, metadata, fields...)
 }
 
 // NewBoolIn is like NewBool but registers in a given context.
-func NewBoolIn(c context.Context, name string, description string, fields ...field.Field) Bool {
+func NewBoolIn(c context.Context, name string, description string, metadata types.MetricMetadata, fields ...field.Field) Bool {
 	m := &boolMetric{metric{MetricInfo: types.MetricInfo{
 		Name:        name,
 		Description: description,
@@ -245,12 +248,12 @@ func NewBoolIn(c context.Context, name string, description string, fields ...fie
 
 // NewCumulativeDistribution returns a new cumulative-distribution-valued
 // metric.  This will panic if another metric already exists with this name.
-func NewCumulativeDistribution(name string, description string, bucketer *distribution.Bucketer, fields ...field.Field) CumulativeDistribution {
-	return NewCumulativeDistributionIn(context.Background(), name, description, bucketer, fields...)
+func NewCumulativeDistribution(name string, description string, metadata types.MetricMetadata, bucketer *distribution.Bucketer, fields ...field.Field) CumulativeDistribution {
+	return NewCumulativeDistributionIn(context.Background(), name, description, metadata, bucketer, fields...)
 }
 
 // NewCumulativeDistributionIn is like NewCumulativeDistribution but registers in a given context.
-func NewCumulativeDistributionIn(c context.Context, name string, description string, bucketer *distribution.Bucketer, fields ...field.Field) CumulativeDistribution {
+func NewCumulativeDistributionIn(c context.Context, name string, description string, metadata types.MetricMetadata, bucketer *distribution.Bucketer, fields ...field.Field) CumulativeDistribution {
 	m := &cumulativeDistributionMetric{
 		nonCumulativeDistributionMetric{
 			metric: metric{MetricInfo: types.MetricInfo{
@@ -268,12 +271,12 @@ func NewCumulativeDistributionIn(c context.Context, name string, description str
 
 // NewNonCumulativeDistribution returns a new non-cumulative-distribution-valued
 // metric.  This will panic if another metric already exists with this name.
-func NewNonCumulativeDistribution(name string, description string, bucketer *distribution.Bucketer, fields ...field.Field) NonCumulativeDistribution {
-	return NewNonCumulativeDistributionIn(context.Background(), name, description, bucketer, fields...)
+func NewNonCumulativeDistribution(name string, description string, metadata types.MetricMetadata, bucketer *distribution.Bucketer, fields ...field.Field) NonCumulativeDistribution {
+	return NewNonCumulativeDistributionIn(context.Background(), name, description, metadata, bucketer, fields...)
 }
 
 // NewNonCumulativeDistributionIn is like NewNonCumulativeDistribution but registers in a given context.
-func NewNonCumulativeDistributionIn(c context.Context, name string, description string, bucketer *distribution.Bucketer, fields ...field.Field) NonCumulativeDistribution {
+func NewNonCumulativeDistributionIn(c context.Context, name string, description string, metadata types.MetricMetadata, bucketer *distribution.Bucketer, fields ...field.Field) NonCumulativeDistribution {
 	m := &nonCumulativeDistributionMetric{
 		metric: metric{MetricInfo: types.MetricInfo{
 			Name:        name,
@@ -289,57 +292,57 @@ func NewNonCumulativeDistributionIn(c context.Context, name string, description
 
 // NewCallbackInt returns a new integer metric whose value is populated by a
 // callback at collection time.
-func NewCallbackInt(name string, description string, fields ...field.Field) CallbackInt {
-	return NewInt(name, description, fields...)
+func NewCallbackInt(name string, description string, metadata types.MetricMetadata, fields ...field.Field) CallbackInt {
+	return NewInt(name, description, metadata, fields...)
 }
 
 // NewCallbackFloat returns a new float metric whose value is populated by a
 // callback at collection time.
-func NewCallbackFloat(name string, description string, fields ...field.Field) CallbackFloat {
-	return NewFloat(name, description, fields...)
+func NewCallbackFloat(name string, description string, metadata types.MetricMetadata, fields ...field.Field) CallbackFloat {
+	return NewFloat(name, description, metadata, fields...)
 }
 
 // NewCallbackString returns a new string metric whose value is populated by a
 // callback at collection time.
-func NewCallbackString(name string, description string, fields ...field.Field) CallbackString {
-	return NewString(name, description, fields...)
+func NewCallbackString(name string, description string, metadata types.MetricMetadata, fields ...field.Field) CallbackString {
+	return NewString(name, description, metadata, fields...)
 }
 
 // NewCallbackBool returns a new bool metric whose value is populated by a
 // callback at collection time.
-func NewCallbackBool(name string, description string, fields ...field.Field) CallbackBool {
-	return NewBool(name, description, fields...)
+func NewCallbackBool(name string, description string, metadata types.MetricMetadata, fields ...field.Field) CallbackBool {
+	return NewBool(name, description, metadata, fields...)
 }
 
 // NewCallbackDistribution returns a new distribution metric whose value is
 // populated by a callback at collection time.
-func NewCallbackDistribution(name string, description string, bucketer *distribution.Bucketer, fields ...field.Field) CallbackDistribution {
-	return NewNonCumulativeDistribution(name, description, bucketer, fields...)
+func NewCallbackDistribution(name string, description string, metadata types.MetricMetadata, bucketer *distribution.Bucketer, fields ...field.Field) CallbackDistribution {
+	return NewNonCumulativeDistribution(name, description, metadata, bucketer, fields...)
 }
 
 // NewCallbackIntIn is like NewCallbackInt but registers in a given context.
-func NewCallbackIntIn(c context.Context, name string, description string, fields ...field.Field) CallbackInt {
-	return NewIntIn(c, name, description, fields...)
+func NewCallbackIntIn(c context.Context, name string, description string, metadata types.MetricMetadata, fields ...field.Field) CallbackInt {
+	return NewIntIn(c, name, description, metadata, fields...)
 }
 
 // NewCallbackFloatIn is like NewCallbackFloat but registers in a given context.
-func NewCallbackFloatIn(c context.Context, name string, description string, fields ...field.Field) CallbackFloat {
-	return NewFloatIn(c, name, description, fields...)
+func NewCallbackFloatIn(c context.Context, name string, description string, metadata types.MetricMetadata, fields ...field.Field) CallbackFloat {
+	return NewFloatIn(c, name, description, metadata, fields...)
 }
 
 // NewCallbackStringIn is like NewCallbackString but registers in a given context.
-func NewCallbackStringIn(c context.Context, name string, description string, fields ...field.Field) CallbackString {
-	return NewStringIn(c, name, description, fields...)
+func NewCallbackStringIn(c context.Context, name string, description string, metadata types.MetricMetadata, fields ...field.Field) CallbackString {
+	return NewStringIn(c, name, description, metadata, fields...)
 }
 
 // NewCallbackBoolIn is like NewCallbackBool but registers in a given context.
-func NewCallbackBoolIn(c context.Context, name string, description string, fields ...field.Field) CallbackBool {
-	return NewBoolIn(c, name, description, fields...)
+func NewCallbackBoolIn(c context.Context, name string, description string, metadata types.MetricMetadata, fields ...field.Field) CallbackBool {
+	return NewBoolIn(c, name, description, metadata, fields...)
 }
 
 // NewCallbackDistributionIn is like NewCallbackDistribution but registers in a given context.
-func NewCallbackDistributionIn(c context.Context, name string, description string, bucketer *distribution.Bucketer, fields ...field.Field) CallbackDistribution {
-	return NewNonCumulativeDistributionIn(c, name, description, bucketer, fields...)
+func NewCallbackDistributionIn(c context.Context, name string, description string, metadata types.MetricMetadata, bucketer *distribution.Bucketer, fields ...field.Field) CallbackDistribution {
+	return NewNonCumulativeDistributionIn(c, name, description, metadata, bucketer, fields...)
 }
 
 // genericGet is a convenience function that tries to get a metric value from
@@ -357,11 +360,13 @@ func (m *metric) genericGet(zero interface{}, c context.Context, fieldVals []int
 
 type metric struct {
 	types.MetricInfo
+	types.MetricMetadata
 	fixedResetTime time.Time
 }
 
-func (m *metric) Info() types.MetricInfo        { return m.MetricInfo }
-func (m *metric) SetFixedResetTime(t time.Time) { m.fixedResetTime = t }
+func (m *metric) Info() types.MetricInfo         { return m.MetricInfo }
+func (m *metric) Metadata() types.MetricMetadata { return m.MetricMetadata }
+func (m *metric) SetFixedResetTime(t time.Time)  { m.fixedResetTime = t }
 
 type intMetric struct{ metric }