[Fix] Fix the path of ceph containing cluster name (#1577)

* [Fix] Fix the path of ceph containing cluster name

* fix corner cases

* fix format

* add note

mmcv/runner/checkpoint.py

@@ -220,11 +220,13 @@ class CheckpointLoader:
             path (str): checkpoint path
 
         Returns:
-            loader (function): checkpoint loader
+            callable: checkpoint loader
         """
-
         for p in cls._schemes:
-            if path.startswith(p):
+            # use regular match to handle some cases that where the prefix of
+            # loader has a prefix. For example, both 's3://path' and
+            # 'open-mmlab:s3://path' should return `load_from_ceph`
+            if re.match(p, path) is not None:
                 return cls._schemes[p]
 
     @classmethod
@@ -326,12 +328,17 @@ def load_from_pavi(filename, map_location=None):
     return checkpoint
 
 
-@CheckpointLoader.register_scheme(prefixes='s3://')
+@CheckpointLoader.register_scheme(prefixes=r'(\S+\:)?s3://')
 def load_from_ceph(filename, map_location=None, backend='petrel'):
     """load checkpoint through the file path prefixed with s3.  In distributed
     setting, this function download ckpt at all ranks to different temporary
     directories.
 
+    Note:
+        Since v1.4.1, the registered scheme prefixes have been enhanced to
+        support bucket names in the path prefix, e.g. 's3://xx.xx/xx.path',
+        'bucket1:s3://xx.xx/xx.path'.
+
     Args:
         filename (str): checkpoint file path with s3 prefix
         map_location (str, optional): Same as :func:`torch.load`.

tests/test_runner/test_checkpoint.py

@@ -347,13 +347,16 @@ def test_checkpoint_loader():
         'modelzoo://xx.xx/xx.pth', 'torchvision://xx.xx/xx.pth',
         'open-mmlab://xx.xx/xx.pth', 'openmmlab://xx.xx/xx.pth',
         'mmcls://xx.xx/xx.pth', 'pavi://xx.xx/xx.pth', 's3://xx.xx/xx.pth',
-        'ss3://xx.xx/xx.pth', ' s3://xx.xx/xx.pth'
+        'ss3://xx.xx/xx.pth', ' s3://xx.xx/xx.pth',
+        'open-mmlab:s3://xx.xx/xx.pth', 'openmmlab:s3://xx.xx/xx.pth',
+        'openmmlabs3://xx.xx/xx.pth', ':s3://xx.xx/xx.path'
     ]
     fn_names = [
         'load_from_http', 'load_from_http', 'load_from_torchvision',
         'load_from_torchvision', 'load_from_openmmlab', 'load_from_openmmlab',
         'load_from_mmcls', 'load_from_pavi', 'load_from_ceph',
-        'load_from_local', 'load_from_local'
+        'load_from_local', 'load_from_local', 'load_from_ceph',
+        'load_from_ceph', 'load_from_local', 'load_from_local'
     ]
 
     for filename, fn_name in zip(filenames, fn_names):