Modify file structure to separate python and cpp code (#223)

Modify code structure

python/fastdeploy/vision/evaluation/utils/util.py

@@ -0,0 +1,34 @@
+# Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import platform
+import multiprocessing as mp
+
+
+def is_pic(img_name):
+    valid_suffix = ['JPEG', 'jpeg', 'JPG', 'jpg', 'BMP', 'bmp', 'PNG', 'png']
+    suffix = img_name.split('.')[-1]
+    if suffix not in valid_suffix:
+        return False
+    return True
+
+
+def get_num_workers(num_workers):
+    if not platform.system() == 'Linux':
+        # Dataloader with multi-process model is not supported
+        # on MacOS and Windows currently.
+        return 0
+    if num_workers == 'auto':
+        num_workers = mp.cpu_count() // 2 if mp.cpu_count() // 2 < 2 else 2
+    return num_workers