From b2b326fc553502de8f82c479f115514315a05b88 Mon Sep 17 00:00:00 2001
From: timofey <tim@ongoteam.yaconnect.com>
Date: Fri, 11 Nov 2022 17:36:29 +0000
Subject: [PATCH] truncation

---
 ptvp35/__init__.py | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/ptvp35/__init__.py b/ptvp35/__init__.py
index f94666f..befc7e1 100644
--- a/ptvp35/__init__.py
+++ b/ptvp35/__init__.py
@@ -113,11 +113,12 @@ class DbConnection:
             factory: 'DbFactory',
     ) -> None:
         self.factory = factory
-        path = self.factory.path
-        self.__path = pathlib.Path(path)
-        self.__path_backup = pathlib.Path(path + '.backup')
-        self.__path_recover = pathlib.Path(path + '.recover')
-        self.__path_error = pathlib.Path(path + '.error')
+        self.__path = path = self.factory.path
+        name = self.__path.name
+        self.__path_backup = path.with_name(name + '.backup')
+        self.__path_recover = path.with_name(name + '.recover')
+        self.__path_error = path.with_name(name + '.error')
+        self.__path_truncate = path.with_name(name + '.truncate')
         self.not_running = True
 
     def _queue_error(self, line: str):
@@ -179,13 +180,17 @@ class DbConnection:
         return buffer
 
     def _file_write(self, line: str):
+        self.__path_truncate.write_bytes(self.__file.tell().to_bytes(16, 'little'))
         self.__file.write(line)
         self.__file.flush()
         os.fsync(self.__file.fileno())
+        self.__path_truncate.unlink(missing_ok=True)
+
+    def _dump_compressed_buffer_sync(self):
+        self._file_write(self._compress_buffer().getvalue())
 
     async def _dump_compressed_buffer(self):
-        buffer = self._compress_buffer()
-        await self.__loop.run_in_executor(None, self._file_write, buffer.getvalue())
+        await self.__loop.run_in_executor(None, self._dump_compressed_buffer_sync)
 
     async def _do_dump_buffer(self):
         await self._dump_compressed_buffer()
@@ -200,9 +205,12 @@ class DbConnection:
             await self._do_dump_buffer()
             await self._reload_if_oversized()
 
-    async def _save_error(self, line: str):
+    def _save_error_sync(self, line: str):
         with open(self.__path_error, 'a') as file:
-            await self.__loop.run_in_executor(None, file.write, line.strip() + '\n')
+            file.write(line.strip() + '\n')
+
+    async def _save_error(self, line: str):
+        await self.__loop.run_in_executor(None, self._save_error_sync, line)
 
     async def _handle_request(self, request: Request):
         if isinstance(request, self.factory.kvrequest_type):
@@ -285,8 +293,18 @@ class DbConnection:
     async def _load_from_file(self):
         await self._rebuild_file(self.__mmdb)
 
+    def _assure_truncation(self):
+        if self.__path_truncate.exists():
+            pos = int.from_bytes(self.__path_truncate.read_bytes(), 'little')
+            with open(self.__path, 'r+') as file:
+                file.seek(pos)
+                asyncio.run_coroutine_threadsafe(self._save_error(file.read()), self.__loop).result()
+                file.truncate(pos)
+        self.__path_truncate.unlink(missing_ok=True)
+
     async def _initialize_mmdb(self):
         self.__mmdb = {}
+        await self.__loop.run_in_executor(None, self._assure_truncation)
         await self._load_from_file()
         self.__file = open(self.__path, "a")
 
@@ -346,7 +364,7 @@ class DbConnection:
 
 class DbFactory:
     def __init__(self, path: str | pathlib.Path, *, kvrequest_type: Type[KVRequest], buffersize=1048576):
-        self.path = path = str(path)
+        self.path = pathlib.Path(path)
         self.kvrequest_type = kvrequest_type
         self.buffersize = buffersize