move retentiongrid to own package

cmd/config/config.go

@@ -6,6 +6,8 @@ import (
 	"github.com/zrepl/yaml-config"
 	"io/ioutil"
 	"os"
+	"regexp"
+	"strconv"
 	"time"
 )
 
@@ -102,11 +104,6 @@ type PruneKeepLastN struct {
 	Count int    `yaml:"count"`
 }
 
-type PruneGrid struct {
-	Type string `yaml:"type"`
-	Grid string `yaml:"grid"`
-}
-
 type LoggingOutletEnum struct {
 	Ret interface{}
 }
@@ -239,3 +236,41 @@ func ParseConfig(path string) (i Config, err error) {
 
 	return
 }
+
+var durationStringRegex *regexp.Regexp = regexp.MustCompile(`^\s*(\d+)\s*(s|m|h|d|w)\s*$`)
+
+func parsePostitiveDuration(e string) (d time.Duration, err error) {
+	comps := durationStringRegex.FindStringSubmatch(e)
+	if len(comps) != 3 {
+		err = fmt.Errorf("does not match regex: %s %#v", e, comps)
+		return
+	}
+
+	durationFactor, err := strconv.ParseInt(comps[1], 10, 64)
+	if err != nil {
+		return 0, err
+	}
+	if durationFactor <= 0 {
+		return 0, errors.New("duration must be positive integer")
+	}
+
+	var durationUnit time.Duration
+	switch comps[2] {
+	case "s":
+		durationUnit = time.Second
+	case "m":
+		durationUnit = time.Minute
+	case "h":
+		durationUnit = time.Hour
+	case "d":
+		durationUnit = 24 * time.Hour
+	case "w":
+		durationUnit = 24 * 7 * time.Hour
+	default:
+		err = fmt.Errorf("contains unknown time unit '%s'", comps[2])
+		return
+	}
+
+	d = time.Duration(durationFactor) * durationUnit
+	return
+}