refine docker layers (#606)

### What problem does this PR solve?


### Type of change

- [x] Performance Improvement

api/utils/file_utils.py

@@ -66,6 +66,15 @@ def get_rag_python_directory(*args):
     return get_rag_directory("python", *args)
 
 
+def get_home_cache_dir():
+    dir = os.path.join(os.path.expanduser('~'), ".raglow")
+    try:
+        os.mkdir(dir)
+    except OSError as error:
+        pass
+    return dir
+
+
 @cached(cache=LRUCache(maxsize=10))
 def load_json_conf(conf_path):
     if os.path.isabs(conf_path):

rag/llm/embedding_model.py

@@ -26,19 +26,17 @@ from FlagEmbedding import FlagModel
 import torch
 import numpy as np
 
-from api.utils.file_utils import get_project_base_directory
+from api.utils.file_utils import get_project_base_directory, get_home_cache_dir
 from rag.utils import num_tokens_from_string
 
 
 try:
-    flag_model = FlagModel(os.path.join(
+    flag_model = FlagModel(os.path.join(get_home_cache_dir(), "bge-large-zh-v1.5"),
-        get_project_base_directory(),
-        "rag/res/bge-large-zh-v1.5"),
         query_instruction_for_retrieval="为这个句子生成表示以用于检索相关文章：",
         use_fp16=torch.cuda.is_available())
 except Exception as e:
     model_dir = snapshot_download(repo_id="BAAI/bge-large-zh-v1.5",
-                                  local_dir=os.path.join(get_project_base_directory(), "rag/res/bge-large-zh-v1.5"),
+                                  local_dir=os.path.join(get_home_cache_dir(), "bge-large-zh-v1.5"),
                                   local_dir_use_symlinks=False)
     flag_model = FlagModel(model_dir,
                            query_instruction_for_retrieval="为这个句子生成表示以用于检索相关文章：",