fix bug about fetching knowledge graph (#3394)

### What problem does this PR solve?


### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/db/services/file_service.py

@@ -15,6 +15,8 @@
 #
 import re
 import os
+from concurrent.futures import ThreadPoolExecutor
+
 from flask_login import current_user
 from peewee import fn
 
@@ -385,6 +387,41 @@ class FileService(CommonService):
 
         return err, files
 
+    @staticmethod
+    def parse_docs(file_objs, user_id):
+        from rag.app import presentation, picture, naive, audio, email
+
+        def dummy(prog=None, msg=""):
+            pass
+
+        FACTORY = {
+            ParserType.PRESENTATION.value: presentation,
+            ParserType.PICTURE.value: picture,
+            ParserType.AUDIO.value: audio,
+            ParserType.EMAIL.value: email
+        }
+        parser_config = {"chunk_token_num": 16096, "delimiter": "\n!?;。；！？", "layout_recognize": False}
+        exe = ThreadPoolExecutor(max_workers=12)
+        threads = []
+        for file in file_objs:
+            kwargs = {
+                "lang": "English",
+                "callback": dummy,
+                "parser_config": parser_config,
+                "from_page": 0,
+                "to_page": 100000,
+                "tenant_id": user_id
+            }
+            filetype = filename_type(file.filename)
+            blob = file.read()
+            threads.append(exe.submit(FACTORY.get(FileService.get_parser(filetype, file.filename, ""), naive).chunk, file.filename, blob, **kwargs))
+
+        res = []
+        for th in threads:
+            res.append("\n".join([ck["content_with_weight"] for ck in th.result()]))
+
+        return "\n\n".join(res)
+
     @staticmethod
     def get_parser(doc_type, filename, default):
         if doc_type == FileType.VISUAL: