enhance: handling abormal iterator cp file(milvus-io#2306)

Signed-off-by: MrPresent-Han <[email protected]>

pymilvus/orm/iterator.py

@@ -145,13 +145,13 @@ def __seek_to_offset(self):
 
     def __init_cp_file_handler(self) -> bool:
         mode = "w"
-        if Path(self._cp_file_path).exists():
+        if self._cp_file_path.exists():
             mode = "r+"
         try:
-            self._cp_file_handler = Path(self._cp_file_path).open(mode)  # noqa: SIM115
+            self._cp_file_handler = self._cp_file_path.open(mode)
         except OSError as ose:
             raise MilvusException(
-                message=f"Failed to open cp file for iterator:{self._cp_file_path}"
+                message=f"Failed to open cp file for iterator:{self._cp_file_path_str}"
             ) from ose
         return mode == "r+"
 
@@ -163,18 +163,26 @@ def __save_mvcc_ts(self):
         self._cp_file_handler.writelines(str(self._session_ts) + "\n")
 
     def __save_pk_cursor(self):
-        if self._need_save_cp:
+        if self._need_save_cp and self._next_id is not None:
+            if not self._cp_file_path.exists():
+                self._cp_file_handler.close()
+                self._cp_file_handler = self._cp_file_path.open("w")
+                self._buffer_cursor_lines_number = 0
+                self.__save_mvcc_ts()
+                log.warning(
+                    "iterator cp file is not existed any more, recreate for iteration, "
+                    "do not remove this file manually!"
+                )
             if self._buffer_cursor_lines_number >= 100:
                 self._cp_file_handler.seek(0)
                 self._cp_file_handler.truncate()
                 log.info(
                     "cursor lines in cp file has exceeded 100 lines, truncate the file and rewrite"
                 )
-                self._cp_file_handler.writelines(str(self._session_ts) + "\n")
-            assert_info(self._next_id is not None, "next_id should not be None when saving cp")
+                self._buffer_cursor_lines_number = 0
             self._cp_file_handler.writelines(str(self._next_id) + "\n")
             self._cp_file_handler.flush()
-            self._buffer_cursor_lines_number = 0
+            self._buffer_cursor_lines_number += 1
 
     def __check_set_reduce_stop_for_best(self):
         if self._kwargs.get(REDUCE_STOP_FOR_BEST, True):
@@ -226,13 +234,15 @@ def __setup_ts_by_request(self):
 
     def __set_up_ts_cp(self):
         self._buffer_cursor_lines_number = 0
-        self._cp_file_path = self._kwargs.get(ITERATOR_SESSION_CP_FILE, None)
+        self._cp_file_path_str = self._kwargs.get(ITERATOR_SESSION_CP_FILE, None)
+        self._cp_file_path = None
         # no input cp_file, set up mvccTs by query request
-        if self._cp_file_path is None:
+        if self._cp_file_path_str is None:
             self._need_save_cp = False
             self.__setup_ts_by_request()
         else:
             self._need_save_cp = True
+            self._cp_file_path = Path(self._cp_file_path_str)
             if not self.__init_cp_file_handler():
                 # input cp file is empty, set up mvccTs by query request
                 self.__setup_ts_by_request()
@@ -244,7 +254,7 @@ def __set_up_ts_cp(self):
                     line_count = len(lines)
                     if line_count < 2:
                         raise ParamError(
-                            message=f"input cp file:{self._cp_file_path} should contain "
+                            message=f"input cp file:{self._cp_file_path_str} should contain "
                             f"at least two lines, but only:{line_count} lines"
                         )
                     self._session_ts = int(lines[0])
@@ -254,7 +264,7 @@ def __set_up_ts_cp(self):
                         self._next_id = lines[self._buffer_cursor_lines_number].strip()
                 except OSError as ose:
                     raise MilvusException(
-                        message=f"Failed to read cp info from file:{self._cp_file_path}"
+                        message=f"Failed to read cp info from file:{self._cp_file_path_str}"
                     ) from ose
                 except ValueError as e:
                     raise ParamError(message=f"cannot parse input cp session_ts:{lines[0]}") from e
@@ -346,11 +356,11 @@ def close(self) -> None:
 
             def inner_close():
                 self._cp_file_handler.close()
-                Path(self._cp_file_path).unlink()
-                log.info(f"removed cp file:{self._cp_file_path} for query iterator")
+                self._cp_file_path.unlink()
+                log.info(f"removed cp file:{self._cp_file_path_str} for query iterator")
 
             io_operation(
-                inner_close, f"failed to clear cp file:{self._cp_file_path} for query iterator"
+                inner_close, f"failed to clear cp file:{self._cp_file_path_str} for query iterator"
             )