diff --git a/notebook/services/contents/fileio.py b/notebook/services/contents/fileio.py index 2fcda7d4a..be38fab09 100644 --- a/notebook/services/contents/fileio.py +++ b/notebook/services/contents/fileio.py @@ -22,6 +22,8 @@ import nbformat from ipython_genutils.py3compat import str_to_unicode +from traitlets.config import Configurable +from traitlets import Bool def copy2_safe(src, dst, log=None): """copy src to dst @@ -39,24 +41,24 @@ def copy2_safe(src, dst, log=None): @contextmanager def atomic_writing(path, text=True, encoding='utf-8', log=None, **kwargs): """Context manager to write to a file only if the entire write is successful. - + This works by copying the previous file contents to a temporary file in the same directory, and renaming that file back to the target if the context exits with an error. If the context is successful, the new data is synced to disk and the temporary file is removed. - + Parameters ---------- path : str The target file to write to. - + text : bool, optional Whether to open the file in text mode (i.e. to write unicode). Default is True. - + encoding : str, optional The encoding to use for files opened in text mode. Default is UTF-8. - + **kwargs Passed to :func:`io.open`. """ @@ -100,7 +102,55 @@ def atomic_writing(path, text=True, encoding='utf-8', log=None, **kwargs): os.remove(tmp_path) -class FileManagerMixin(object): + +@contextmanager +def _simple_writing(path, text=True, encoding='utf-8', **kwargs): + """Context manager to write file without doing atomic writing + ( for weird filesystem eg: nfs). + + Parameters + ---------- + path : str + The target file to write to. + + text : bool, optional + Whether to open the file in text mode (i.e. to write unicode). Default is + True. + + encoding : str, optional + The encoding to use for files opened in text mode. Default is UTF-8. + + **kwargs + Passed to :func:`io.open`. + """ + # realpath doesn't work on Windows: http://bugs.python.org/issue9949 + # Luckily, we only need to resolve the file itself being a symlink, not + # any of its directories, so this will suffice: + if os.path.islink(path): + path = os.path.join(os.path.dirname(path), os.readlink(path)) + + if text: + # Make sure that text files have Unix linefeeds by default + kwargs.setdefault('newline', '\n') + fileobj = io.open(path, 'w', encoding=encoding, **kwargs) + else: + fileobj = io.open(path, 'wb', **kwargs) + + try: + yield fileobj + except: + fileobj.close() + raise + + # Flush to disk + fileobj.flush() + os.fsync(fileobj.fileno()) + fileobj.close() + + + + +class FileManagerMixin(Configurable): """ Mixin for ContentsAPI classes that interact with the filesystem. @@ -119,6 +169,9 @@ class FileManagerMixin(object): log : logging.Logger """ + use_atomic_writing = Bool(True, config=True, help="""flag to deactivate + atomic writing on slow (like networked) file system.""") + @contextmanager def open(self, os_path, *args, **kwargs): """wrapper around io.open that turns permission errors into 403""" @@ -130,8 +183,12 @@ class FileManagerMixin(object): def atomic_writing(self, os_path, *args, **kwargs): """wrapper around atomic_writing that turns permission errors to 403""" with self.perm_to_403(os_path): - with atomic_writing(os_path, *args, log=self.log, **kwargs) as f: - yield f + if self.use_atomic_writing: + with atomic_writing(os_path, *args, log=self.log, **kwargs) as f: + yield f + else: + with simple_writing(os_path, *args, log=self.log, **kwargs) as f: + yield f @contextmanager def perm_to_403(self, os_path=''):