backup and recover

ptvp35/__init__.py

@@ -2,6 +2,7 @@ import asyncio
 import json
 import pathlib
 import pickle
+import shutil
 from io import StringIO
 from typing import Any, Optional, IO, Type
 
@@ -80,9 +81,12 @@ class Db:
     __task: Optional[asyncio.Future]
 
     def __init__(self, path: str, *, kvrequest_type: Type[KVRequest], buffersize=1048576):
+        path = str(path)
         self.kvrequest_type = kvrequest_type
         self.buffersize = buffersize
         self.__path = pathlib.Path(path)
+        self.__path_backup = pathlib.Path(path + '.backup')
+        self.__path_recover = pathlib.Path(path + '.recover')
         self.__task = None
 
     def io2db(self, io: IO[str], db: dict) -> int:
@@ -174,11 +178,19 @@ class Db:
             await self._background_cycle()
 
     def _rebuild_file(self, db: {}):
+        if self.__path_recover.exists():
+            shutil.copy(self.__path_backup, self.__path)
+            self.__path_recover.unlink()
+            self.__path_backup.unlink()
         self.__path.touch()
         with open(self.__path) as file:
             self.io2db(file, db)
-        with open(self.__path, "w") as file:
+        with open(self.__path_backup, "w") as file:
             self.__initial_size = self.db2io(db, file)
+        self.__path_recover.touch()
+        shutil.copy(self.__path_backup, self.__path)
+        self.__path_recover.unlink()
+        self.__path_backup.unlink()
 
     def _reload(self):
         self.__file.close()