enalbe memcached support in PetrelBackend (#341)

mmcv/fileio/file_client.py

@@ -60,16 +60,17 @@ class PetrelBackend(BaseStorageBackend):
         path_mapping (dict|None): path mapping dict from local path to Petrel
             path. When `path_mapping={'src': 'dst'}`, `src` in `filepath` will
             be replaced by `dst`. Default: None.
+        enable_mc (bool): whether to enable memcached support. Default: True.
     """
 
-    def __init__(self, path_mapping=None):
+    def __init__(self, path_mapping=None, enable_mc=True):
         try:
             from petrel_client import client
         except ImportError:
             raise ImportError('Please install petrel_client to enable '
                               'PetrelBackend.')
 
-        self._client = client.Client()
+        self._client = client.Client(enable_mc=enable_mc)
         assert isinstance(path_mapping, dict) or path_mapping is None
         self.path_mapping = path_mapping
 

tests/test_fileclient.py

@@ -15,6 +15,9 @@ sys.modules['mc'] = MagicMock()
 
 class MockS3Client(object):
 
+    def __init__(self, enable_mc=True):
+        self.enable_mc = enable_mc
+
     def Get(self, filepath):
         with open(filepath, 'rb') as f:
             content = f.read()