Optimize move.move_file for moving files between different OSFS instances.

CONTRIBUTORS.md

@@ -40,6 +40,7 @@ Many thanks to the following developers for contributing to this project:
 - [Silvan Spross](https://github.com/sspross)
 - [@sqwishy](https://github.com/sqwishy)
 - [Sven Schliesing](https://github.com/muffl0n)
+- [Thomas Feldmann](https://github.com/tfeldmann)
 - [Tim Gates](https://github.com/timgates42/)
 - [@tkossak](https://github.com/tkossak)
 - [Todd Levi](https://github.com/televi)

fs/move.py

@@ -4,11 +4,15 @@
 from __future__ import print_function
 from __future__ import unicode_literals
 
+from os.path import commonpath
 import typing
 
+from . import open_fs
 from .copy import copy_dir
 from .copy import copy_file
+from .errors import ResourceReadOnly
 from .opener import manage_fs
+from .path import frombase
 
 if typing.TYPE_CHECKING:
     from .base import FS
@@ -55,6 +59,31 @@ def move_file(
             resources (defaults to `False`).
 
     """
+    if src_fs.hassyspath(src_path) and dst_fs.hassyspath(dst_path):
+        # we have to raise a ResourceReadOnly exception manually if a FS is read-only
+        if src_fs.getmeta().get("read_only", True):
+            raise ResourceReadOnly(src_fs, src_path)
+        if dst_fs.getmeta().get("read_only", True):
+            raise ResourceReadOnly(dst_fs, dst_path)
+
+        # if both filesystems have a syspath we create a new OSFS from a
+        # common parent folder and use it to move the file.
+        with manage_fs(src_fs) as _src_fs:
+            with manage_fs(dst_fs, create=True) as _dst_fs:
+                try:
+                    src_syspath = src_fs.getsyspath(src_path)
+                    dst_syspath = dst_fs.getsyspath(dst_path)
+                    common = commonpath([src_syspath, dst_syspath])
+                    rel_src = frombase(common, src_syspath)
+                    rel_dst = frombase(common, dst_syspath)
+                    with _src_fs.lock(), _dst_fs.lock(), open_fs(
+                        common, writeable=True
+                    ) as base:
+                        base.move(rel_src, rel_dst, preserve_time=preserve_time)
+                    return  # optimization worked, exit early
+                except ValueError:
+                    pass
+
     with manage_fs(src_fs) as _src_fs:
         with manage_fs(dst_fs, create=True) as _dst_fs:
             if _src_fs is _dst_fs:

fs/wrap.py

@@ -31,6 +31,7 @@
         Dict,
         Iterator,
         IO,
+        Mapping,
         Optional,
         Text,
         Tuple,
@@ -320,3 +321,11 @@ def touch(self, path):
         # type: (Text) -> None
         self.check()
         raise ResourceReadOnly(path)
+
+    def getmeta(self, namespace="standard"):
+        # type: (Text) -> Mapping[Text, object]
+        self.check()
+        meta = self.delegate_fs().getmeta(namespace=namespace)
+        meta["read_only"] = True
+        meta["supports_rename"] = False
+        return meta

tests/test_move.py

@@ -6,6 +6,7 @@
 
 import fs.move
 from fs import open_fs
+from fs.path import join
 
 
 @parameterized_class(("preserve_time",), [(True,), (False,)])
@@ -37,6 +38,17 @@ def test_move_fs(self):
             self.assertEqual(dst_file1_info.modified, src_file1_info.modified)
             self.assertEqual(dst_file2_info.modified, src_file2_info.modified)
 
+    def test_move_file(self):
+        with open_fs("temp://") as temp:
+            syspath = temp.getsyspath("/")
+            a = open_fs(syspath)
+            a.makedir("dir")
+            b = open_fs(join(syspath, "dir"))
+            b.writetext("file.txt", "Content")
+            fs.move.move_file(b, "file.txt", a, "here.txt")
+            self.assertEqual(a.readtext("here.txt"), "Content")
+            self.assertFalse(b.exists("file.txt"))
+
     def test_move_dir(self):
         namespaces = ("details", "modified")