WIP: break exporter apart so it can run as an idiomatic library.

exporter/dbconv/dbconv.go

@@ -0,0 +1,63 @@
+package dbconv
+
+import (
+	"time"
+	"strconv"
+	"github.com/prometheus/common/log"
+	"math"
+	"fmt"
+)
+
+// DbToFloat64 converts database.sql types to float64s for Prometheus consumption. Null types are mapped to NaN. string
+// and []byte types are mapped as NaN and !ok
+func DbToFloat64(t interface{}) (float64, bool) {
+	switch v := t.(type) {
+	case int64:
+		return float64(v), true
+	case float64:
+		return v, true
+	case time.Time:
+		return float64(v.Unix()), true
+	case []byte:
+		// Try and convert to string and then parse to a float64
+		strV := string(v)
+		result, err := strconv.ParseFloat(strV, 64)
+		if err != nil {
+			log.Infoln("Could not parse []byte:", err)
+			return math.NaN(), false
+		}
+		return result, true
+	case string:
+		result, err := strconv.ParseFloat(v, 64)
+		if err != nil {
+			log.Infoln("Could not parse string:", err)
+			return math.NaN(), false
+		}
+		return result, true
+	case nil:
+		return math.NaN(), true
+	default:
+		return math.NaN(), false
+	}
+}
+
+// DbToString converts database.sql to string for Prometheus labels. Null types are mapped to empty strings.
+func DbToString(t interface{}) (string, bool) {
+	switch v := t.(type) {
+	case int64:
+		return fmt.Sprintf("%v", v), true
+	case float64:
+		return fmt.Sprintf("%v", v), true
+	case time.Time:
+		return fmt.Sprintf("%v", v.Unix()), true
+	case nil:
+		return "", true
+	case []byte:
+		// Try and convert to string
+		return string(v), true
+	case string:
+		return v, true
+	default:
+		return "", false
+	}
+}