Implemented retryupdate

retryupdate/update.go

@@ -2,8 +2,67 @@
 
 package retryupdate
 
-import "gitlab.com/slon/shad-go/retryupdate/kvapi"
+import (
+	"errors"
+	"fmt"
+
+	"github.com/gofrs/uuid"
+	"gitlab.com/slon/shad-go/retryupdate/kvapi"
+)
+
+var (
+	authError     *kvapi.AuthError
+	conflictError *kvapi.ConflictError
+)
 
 func UpdateValue(c kvapi.Client, key string, updateFn func(oldValue *string) (newValue string, err error)) error {
-	panic("implement me")
+	newVersion := uuid.Must(uuid.NewV4())
+get:
+	for {
+		old, err := c.Get(&kvapi.GetRequest{Key: key})
+		var value *string
+		oldUuid := uuid.Nil
+		if err != nil {
+			switch {
+			case errors.As(err, &authError):
+				return err
+			case !errors.Is(err, kvapi.ErrKeyNotFound):
+				continue
+			}
+		} else {
+			value = &old.Value
+			oldUuid = old.Version
+		}
+		for {
+			new, err := updateFn(value)
+			if err != nil {
+				return err
+			}
+			_, err = c.Set(&kvapi.SetRequest{
+				Key:        key,
+				Value:      new,
+				OldVersion: oldUuid,
+				NewVersion: newVersion,
+			})
+			if err != nil {
+				fmt.Println(err)
+				switch {
+				case errors.As(err, &conflictError):
+					if conflictError.ExpectedVersion == newVersion {
+						return nil
+					}
+					continue get
+				case errors.Is(err, kvapi.ErrKeyNotFound):
+					value = nil
+					oldUuid = uuid.Nil
+					continue
+				case errors.As(err, &authError):
+					return err
+				default:
+					continue
+				}
+			}
+			return nil
+		}
+	}
 }