Add generic interface for float/histogram sample pair (bumping go ver…

…sion - experimental)

Signed-off-by: Jeanette Tan <[email protected]>

go.mod

@@ -1,6 +1,6 @@
 module github.com/prometheus/common
 
-go 1.17
+go 1.18
 
 require (
 	github.com/go-kit/log v0.2.1

model/value.go

@@ -379,3 +379,8 @@ func (mat Matrix) String() string {
 
 	return strings.Join(strs, "\n")
 }
+
+type GenericSamplePair interface {
+	SamplePair | SampleHistogramPair
+	GetTimestamp() Time
+}

model/value_float.go

@@ -99,3 +99,7 @@ func (s *SamplePair) Equal(o *SamplePair) bool {
 func (s SamplePair) String() string {
 	return fmt.Sprintf("%s @[%s]", s.Value, s.Timestamp)
 }
+
+func (s SamplePair) GetTimestamp() Time {
+	return s.Timestamp
+}

model/value_histogram.go

@@ -169,3 +169,7 @@ func (s SampleHistogramPair) String() string {
 func (s *SampleHistogramPair) Equal(o *SampleHistogramPair) bool {
 	return s == o || (s.Histogram.Equal(&o.Histogram) && s.Timestamp.Equal(o.Timestamp))
 }
+
+func (s SampleHistogramPair) GetTimestamp() Time {
+	return s.Timestamp
+}