Implement pod deletion cost

pkg/apis/core/helper/helpers.go

@@ -19,6 +19,7 @@ package helper
 import (
 	"encoding/json"
 	"fmt"
+	"strconv"
 	"strings"
 
 	"k8s.io/apimachinery/pkg/api/resource"
@@ -532,3 +533,29 @@ func ToPodResourcesSet(podSpec *core.PodSpec) sets.String {
 	}
 	return result
 }
+
+// GetDeletionCostFromPodAnnotations returns the integer value of pod-deletion-cost. Returns 0
+// if not set or the value is invalid.
+func GetDeletionCostFromPodAnnotations(annotations map[string]string) (int32, error) {
+	if value, exist := annotations[core.PodDeletionCost]; exist {
+		// values that start with plus sign (e.g, "+10") or leading zeros (e.g., "008") are not valid.
+		if !validFirstDigit(value) {
+			return 0, fmt.Errorf("invalid value %q", value)
+		}
+
+		i, err := strconv.ParseInt(value, 10, 32)
+		if err != nil {
+			// make sure we default to 0 on error.
+			return 0, err
+		}
+		return int32(i), nil
+	}
+	return 0, nil
+}
+
+func validFirstDigit(str string) bool {
+	if len(str) == 0 {
+		return false
+	}
+	return str[0] == '-' || (str[0] == '0' && str == "0") || (str[0] >= '1' && str[0] <= '9')
+}