postgres_exporter/pkg/pgdbconv/dbconv.go

// package dbconv defines functions to intelligently convert to and from postgres specific datatypes for metric
// purposes
package pgdbconv

import (
	"fmt"
	"github.com/prometheus/common/log"
	"math"
	"strconv"
	"time"
)

// 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 bool:
		if v {
			return 1.0, true
		}
		return 0.0, 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
	case bool:
		if v {
			return "true", true
		}
		return "false", true
	default:
		return "", false
	}
}