Move consistent NaN logic into the parser.

pkg/textparse/lex.l

@@ -18,6 +18,8 @@ import (
         "fmt"
         "math"
         "strconv"
+
+        "github.com/prometheus/prometheus/pkg/value"
 )
 
 
@@ -85,8 +87,9 @@ M     [a-zA-Z_:]
                                       l.offsets = append(l.offsets, l.i-1)
 
 <lstateValue>[ \t]+                   l.vstart = l.i
-<lstateValue>(NaN)                    l.val = math.NaN()
+<lstateValue>(NaN)                    l.val = math.Float64frombits(value.NormalNaN)
                                       s = lstateTimestamp
+
 <lstateValue>[^\n \t\r]+              // We don't parse strictly correct floats as the conversion
                                       // repeats the effort anyway.
                                       l.val, l.err = strconv.ParseFloat(yoloString(l.b[l.vstart:l.i]), 64)

pkg/textparse/lex.l.go

@@ -19,6 +19,8 @@ import (
 	"fmt"
 	"math"
 	"strconv"
+
+	"github.com/prometheus/prometheus/pkg/value"
 )
 
 // Lex is called by the parser generated by "go tool yacc" to obtain each
@@ -426,7 +428,7 @@ yyrule12: // [ \t]+
 	}
 yyrule13: // (NaN)
 	{
-		l.val = math.NaN()
+		l.val = math.Float64frombits(value.NormalNaN)
 		s = lstateTimestamp
 		goto yystate0
 	}

pkg/value/value.go

@@ -14,6 +14,6 @@
 package value
 
 var (
-	normalNaN uint64 = 0x7ff8000000000001 // A quiet NaN. This is also math.NaN().
-	staleNaN  uint64 = 0x7ff4000000000000 // A signalling NaN, starting 01 to allow for expansion.
+	NormalNaN uint64 = 0x7ff8000000000001 // A quiet NaN. This is also math.NaN().
+	StaleNaN  uint64 = 0x7ff4000000000000 // A signalling NaN, starting 01 to allow for expansion.
 )

retrieval/scrape.go

@@ -19,7 +19,6 @@ import (
 	"compress/gzip"
 	"fmt"
 	"io"
-	"math"
 	"net/http"
 	"sync"
 	"time"
@@ -47,11 +46,6 @@ const (
 	samplesPostRelabelMetricName = "scrape_samples_post_metric_relabeling"
 )
 
-var (
-	normalNaN uint64 = 0x7ff8000000000001 // A quiet NaN. This is also math.NaN().
-	staleNaN  uint64 = 0x7ff4000000000000 // A signalling NaN, starting 01 to allow for expansion.
-)
-
 var (
 	targetIntervalLength = prometheus.NewSummaryVec(
 		prometheus.SummaryOpts{
@@ -542,10 +536,6 @@ loop:
 
 		t := defTime
 		met, tp, v := p.At()
-		// Normalise actual NaNs to one bit representation.
-		if math.IsNaN(v) {
-			v = math.Float64frombits(normalNaN)
-		}
 		if tp != nil {
 			t = *tp
 		}

retrieval/scrape_test.go

@@ -18,10 +18,10 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
-	"math"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
+	"math"
 	"reflect"
 	"strings"
 	"sync"
@@ -35,6 +35,7 @@ import (
 	"github.com/prometheus/prometheus/config"
 	"github.com/prometheus/prometheus/pkg/labels"
 	"github.com/prometheus/prometheus/pkg/timestamp"
+	"github.com/prometheus/prometheus/pkg/value"
 	"github.com/prometheus/prometheus/storage"
 )
 
@@ -451,8 +452,8 @@ func TestScrapeLoopAppend(t *testing.T) {
 	}
 
 	ingestedNaN := math.Float64bits(app.result[1].v)
-	if ingestedNaN != normalNaN {
-		t.Fatalf("Appended NaN samples wasn't as expected. Wanted: %x Got: %x", normalNaN, ingestedNaN)
+	if ingestedNaN != value.NormalNaN {
+		t.Fatalf("Appended NaN samples wasn't as expected. Wanted: %x Got: %x", value.NormalNaN, ingestedNaN)
 	}
 
 	// DeepEqual will report NaNs as being different, so replace with a different value.