Use expfmt.writeEscapedString instead of strconv.Quote

Signed-off-by: Owen Williams <[email protected]>
prometheus · Dec 14, 2023 · 680c492 · 680c492
1 parent c3e03fd
commit 680c492
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Showing 3 changed files with 35 additions and 31 deletions.
diff --git a/expfmt/openmetrics_create.go b/expfmt/openmetrics_create.go
@@ -90,11 +90,6 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 	if metricType == dto.MetricType_COUNTER && strings.HasSuffix(shortName, "_total") {
 		shortName = name[:len(name)-6]
 	}
-	// If the name does not satisfy the legacy validity check, we must quote it.
-	quotedName := shortName
-	if !model.IsValidLegacyMetricName(model.LabelValue(quotedName)) {
-		quotedName = strconv.Quote(quotedName)
-	}
 
 	// Comments, first HELP, then TYPE.
 	if in.Help != nil {
@@ -103,7 +98,7 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 		if err != nil {
 			return
 		}
-		n, err = w.WriteString(quotedName)
+		n, err = writeName(w, shortName)
 		written += n
 		if err != nil {
 			return
@@ -129,7 +124,7 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 	if err != nil {
 		return
 	}
-	n, err = w.WriteString(quotedName)
+	n, err = writeName(w, shortName)
 	written += n
 	if err != nil {
 		return
@@ -382,10 +377,10 @@ func writeOpenMetricsNameAndLabelPairs(
 			if err != nil {
 				return written, err
 			}
-			name = strconv.Quote(name)
 			separator = ','
 		}
-		n, err := w.WriteString(name)
+
+		n, err := writeName(w, name)
 		written += n
 		if err != nil {
 			return written, err
@@ -409,11 +404,7 @@ func writeOpenMetricsNameAndLabelPairs(
 		if err != nil {
 			return written, err
 		}
-		labelName := lp.GetName()
-		if !model.IsValidLegacyMetricName(model.LabelValue(labelName)) {
-			labelName = strconv.Quote(labelName)
-		}
-		n, err := w.WriteString(labelName)
+		n, err := writeName(w, lp.GetName())
 		written += n
 		if err != nil {
 			return written, err

diff --git a/expfmt/text_create.go b/expfmt/text_create.go
@@ -73,11 +73,6 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err e
 		return 0, fmt.Errorf("MetricFamily has no name: %s", in)
 	}
 
-	// If the name does not satisfy the legacy validity check, we must quote it.
-	quotedName := name
-	if !model.IsValidLegacyMetricName(model.LabelValue(quotedName)) {
-		quotedName = strconv.Quote(quotedName)
-	}
 	// Try the interface upgrade. If it doesn't work, we'll use a
 	// bufio.Writer from the sync.Pool.
 	w, ok := out.(enhancedWriter)
@@ -103,7 +98,7 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err e
 		if err != nil {
 			return
 		}
-		n, err = w.WriteString(quotedName)
+		n, err = writeName(w, name)
 		written += n
 		if err != nil {
 			return
@@ -129,7 +124,7 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err e
 	if err != nil {
 		return
 	}
-	n, err = w.WriteString(quotedName)
+	n, err = writeName(w, name)
 	written += n
 	if err != nil {
 		return
@@ -344,18 +339,17 @@ func writeNameAndLabelPairs(
 
 	if name != "" {
 		// If the name does not pass the legacy validity check, we must put the
-		// metric name inside the braces. Note, it will already have been
+		// metric name inside the braces.
 		if !model.IsValidLegacyMetricName(model.LabelValue(name)) {
 			metricInsideBraces = true
 			err := w.WriteByte(separator)
 			written++
 			if err != nil {
 				return written, err
 			}
-			name = strconv.Quote(name)
 			separator = ','
 		}
-		n, err := w.WriteString(name)
+		n, err := writeName(w, name)
 		written += n
 		if err != nil {
 			return written, err
@@ -379,11 +373,7 @@ func writeNameAndLabelPairs(
 		if err != nil {
 			return written, err
 		}
-		labelName := lp.GetName()
-		if !model.IsValidLegacyMetricName(model.LabelValue(labelName)) {
-			labelName = strconv.Quote(labelName)
-		}
-		n, err := w.WriteString(labelName)
+		n, err := writeName(w, lp.GetName())
 		written += n
 		if err != nil {
 			return written, err
@@ -490,3 +480,27 @@ func writeInt(w enhancedWriter, i int64) (int, error) {
 	numBufPool.Put(bp)
 	return written, err
 }
+
+// writeName writes a string as-is if it complies with the legacy naming
+// scheme, or escapes it in double quotes if not.
+func writeName(w enhancedWriter, name string) (int, error) {
+	if !model.IsValidLegacyMetricName(model.LabelValue(name)) {
+		var written int
+		var err error
+		err = w.WriteByte('"')
+		written++
+		if err != nil {
+			return written, err
+		}
+		var n int
+		n, err = writeEscapedString(w, name, true)
+		written += n
+		if err != nil {
+			return written, err
+		}
+		err = w.WriteByte('"')
+		written++
+		return written, err
+	}
+	return w.WriteString(name)
+}
diff --git a/model/metric.go b/model/metric.go
@@ -116,8 +116,7 @@ func IsValidMetricName(n LabelValue) bool {
 }
 
 // IsValidLegacyMetricName is similar to IsValidMetricName but always uses the
-// legacy validation scheme regardless of the value of NameValidationScheme. It
-// returns true iff name matches the pattern of MetricNameRE for legacy names.
+// legacy validation scheme regardless of the value of NameValidationScheme.
 // This function, however, does not use MetricNameRE for the check but a much
 // faster hardcoded implementation.
 func IsValidLegacyMetricName(n LabelValue) bool {