Work around a bug in setting and getting the mtime in python 2

See http://bugs.python.org/issue12904.  Basically, we can get the mtime in
nanosecond precision, but only set it in microsecond precision.  This means
that the shutil.copy2 will not set the destination's mtime to exactly the same
mtime as our source.  The end result is that we can *always* end up copying
the extension because the source always appears newer.  We add a microsecond of fudge time when checking to see
if the source is newer than the destination to get around this.

This bug is fixed in Python 3.3+, I believe.

IPython/html/nbextensions.py

@@ -1,344 +1,346 b''
 # coding: utf-8
 """Utilities for installing Javascript extensions for the notebook"""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 from __future__ import print_function
 
 import os
 import shutil
 import sys
 import tarfile
 import zipfile
 import uuid
 from os.path import basename, join as pjoin
 
 # Deferred imports
 try:
     from urllib.parse import urlparse  # Py3
     from urllib.request import urlretrieve
 except ImportError:
     from urlparse import urlparse
     from urllib import urlretrieve
 
 from IPython.utils.path import get_ipython_dir, ensure_dir_exists
 from IPython.utils.py3compat import string_types, cast_unicode_py2
 from IPython.utils.tempdir import TemporaryDirectory
 
 class ArgumentConflict(ValueError):
     pass
 
 # Packagers: modify the next block if you store system-installed nbextensions elsewhere (unlikely)
 SYSTEM_NBEXTENSIONS_DIRS = []
 
 if os.name == 'nt':
     programdata = os.environ.get('PROGRAMDATA', None)
     if programdata: # PROGRAMDATA is not defined by default on XP.
         SYSTEM_NBEXTENSIONS_DIRS = [pjoin(programdata, 'jupyter', 'nbextensions')]
     prefixes = []
 else:
     prefixes = [os.path.sep + pjoin('usr', 'local'), os.path.sep + 'usr']
 
 # add sys.prefix at the front
 if sys.prefix not in prefixes:
     prefixes.insert(0, sys.prefix)
 
 for prefix in prefixes:
     nbext = pjoin(prefix, 'share', 'jupyter', 'nbextensions')
     if nbext not in SYSTEM_NBEXTENSIONS_DIRS:
         SYSTEM_NBEXTENSIONS_DIRS.append(nbext)
 
 if os.name == 'nt':
     # PROGRAMDATA
     SYSTEM_NBEXTENSIONS_INSTALL_DIR = SYSTEM_NBEXTENSIONS_DIRS[-1]
 else:
     # /usr/local
     SYSTEM_NBEXTENSIONS_INSTALL_DIR = SYSTEM_NBEXTENSIONS_DIRS[-2]
 
 
 def _should_copy(src, dest, verbose=1):
     """should a file be copied?"""
     if not os.path.exists(dest):
         return True
-    if os.stat(dest).st_mtime < os.stat(src).st_mtime:
+    if os.stat(src).st_mtime - os.stat(dest).st_mtime > 1e-6:
+        # we add a fudge factor to work around a bug in python 2.x
+        # that was fixed in python 3.x: http://bugs.python.org/issue12904
         if verbose >= 2:
             print("%s is out of date" % dest)
         return True
     if verbose >= 2:
         print("%s is up to date" % dest)
     return False
 
 
 def _maybe_copy(src, dest, verbose=1):
     """copy a file if it needs updating"""
     if _should_copy(src, dest, verbose):
         if verbose >= 1:
             print("copying %s -> %s" % (src, dest))
         try:
             shutil.copy2(src, dest)
         except IOError as e:
             print(str(e), file=sys.stderr)
 
 def _safe_is_tarfile(path):
     """safe version of is_tarfile, return False on IOError"""
     try:
         return tarfile.is_tarfile(path)
     except IOError:
         return False
 
 
 def check_nbextension(files, nbextensions_dir=None):
     """Check whether nbextension files have been installed
     
     files should be a list of relative paths within nbextensions.
     
     Returns True if all files are found, False if any are missing.
     """
     if nbextensions_dir:
         nbext = nbextensions_dir
     else:
         nbext = pjoin(get_ipython_dir(), u'nbextensions')
     # make sure nbextensions dir exists
     if not os.path.exists(nbext):
         return False
     
     if isinstance(files, string_types):
         # one file given, turn it into a list
         files = [files]
     
     return all(os.path.exists(pjoin(nbext, f)) for f in files)
 
 
 def install_nbextension(files, overwrite=False, symlink=False, user=False, prefix=None, nbextensions_dir=None, verbose=1):
     """Install a Javascript extension for the notebook
     
     Stages files and/or directories into the nbextensions directory.
     By default, this compares modification time, and only stages files that need updating.
     If `overwrite` is specified, matching files are purged before proceeding.
     
     Parameters
     ----------
     
     files : list(paths or URLs) or dict(install_name: path or URL)
         One or more paths or URLs to existing files directories to install.
         If given as a list, these will be installed with their base name, so '/path/to/foo'
         will install to 'nbextensions/foo'.  If given as a dict, such as {'bar': '/path/to/foo'},
         then '/path/to/foo' will install to 'nbextensions/bar'.
         Archives (zip or tarballs) will be extracted into the nbextensions directory.
     overwrite : bool [default: False]
         If True, always install the files, regardless of what may already be installed.
     symlink : bool [default: False]
         If True, create a symlink in nbextensions, rather than copying files.
         Not allowed with URLs or archives. Windows support for symlinks requires
         Vista or above, Python 3, and a permission bit which only admin users
         have by default, so don't rely on it.
     user : bool [default: False]
         Whether to install to the user's .ipython/nbextensions directory.
         Otherwise do a system-wide install (e.g. /usr/local/share/jupyter/nbextensions).
     prefix : str [optional]
         Specify install prefix, if it should differ from default (e.g. /usr/local).
         Will install to prefix/share/jupyter/nbextensions
     nbextensions_dir : str [optional]
         Specify absolute path of nbextensions directory explicitly.
     verbose : int [default: 1]
         Set verbosity level. The default is 1, where file actions are printed.
         set verbose=2 for more output, or verbose=0 for silence.
     """
     if sum(map(bool, [user, prefix, nbextensions_dir])) > 1:
         raise ArgumentConflict("Cannot specify more than one of user, prefix, or nbextensions_dir.")
     if user:
         nbext = pjoin(get_ipython_dir(), u'nbextensions')
     else:
         if prefix:
             nbext = pjoin(prefix, 'share', 'jupyter', 'nbextensions')
         elif nbextensions_dir:
             nbext = nbextensions_dir
         else:
             nbext = SYSTEM_NBEXTENSIONS_INSTALL_DIR
     # make sure nbextensions dir exists
     ensure_dir_exists(nbext)
     
     if isinstance(files, string_types):
         # one file given, turn it into a list
         files = [files]
     if isinstance(files, (list,tuple)):
         # list given, turn into dict
         _files = {}
         for path in map(cast_unicode_py2, files):
             if path.startswith(('https://', 'http://')):
                 destination = urlparse(path).path.split('/')[-1]
             elif path.endswith('.zip') or _safe_is_tarfile(path):
                 destination = str(uuid.uuid4()) # ignored for archives
             else:
                 destination = basename(path)
             _files[destination] = path
         files = _files
     
     for dest_basename,path in (map(cast_unicode_py2, item) for item in files.items()):
         
         if path.startswith(('https://', 'http://')):
             if symlink:
                 raise ValueError("Cannot symlink from URLs")
             # Given a URL, download it
             with TemporaryDirectory() as td:
                 filename = urlparse(path).path.split('/')[-1]
                 local_path = os.path.join(td, filename)
                 if verbose >= 1:
                     print("downloading %s to %s" % (path, local_path))
                 urlretrieve(path, local_path)
                 # now install from the local copy
                 install_nbextension({dest_basename: local_path}, overwrite=overwrite, symlink=symlink, nbextensions_dir=nbext, verbose=verbose)
             continue
         
         # handle archives
         archive = None
         if path.endswith('.zip'):
             archive = zipfile.ZipFile(path)
         elif _safe_is_tarfile(path):
             archive = tarfile.open(path)
         
         if archive:
             if symlink:
                 raise ValueError("Cannot symlink from archives")
             if verbose >= 1:
                 print("extracting %s to %s" % (path, nbext))
             archive.extractall(nbext)
             archive.close()
             continue
         
         dest = pjoin(nbext, dest_basename)
         if overwrite and os.path.exists(dest):
             if verbose >= 1:
                 print("removing %s" % dest)
             if os.path.isdir(dest) and not os.path.islink(dest):
                 shutil.rmtree(dest)
             else:
                 os.remove(dest)
         
         if symlink:
             path = os.path.abspath(path)
             if not os.path.exists(dest):
                 if verbose >= 1:
                     print("symlink %s -> %s" % (dest, path))
                 os.symlink(path, dest)
             continue
 
         if os.path.isdir(path):
             path = pjoin(os.path.abspath(path), '') # end in path separator
             for parent, dirs, files in os.walk(path):
                 dest_dir = pjoin(dest, parent[len(path):])
                 if not os.path.exists(dest_dir):
                     if verbose >= 2:
                         print("making directory %s" % dest_dir)
                     os.makedirs(dest_dir)
                 for file in files:
                     src = pjoin(parent, file)
                     # print("%r, %r" % (dest_dir, file))
                     dest_file = pjoin(dest_dir, file)
                     _maybe_copy(src, dest_file, verbose)
         else:
             src = path
             _maybe_copy(src, dest, verbose)
 
 #----------------------------------------------------------------------
 # install nbextension app
 #----------------------------------------------------------------------
 
 from IPython.utils.traitlets import Bool, Enum, Unicode, TraitError
 from IPython.core.application import BaseIPythonApplication
 
 flags = {
     "overwrite" : ({
         "NBExtensionApp" : {
             "overwrite" : True,
         }}, "Force overwrite of existing files"
     ),
     "debug" : ({
         "NBExtensionApp" : {
             "verbose" : 2,
         }}, "Extra output"
     ),
     "quiet" : ({
         "NBExtensionApp" : {
             "verbose" : 0,
         }}, "Minimal output"
     ),
     "symlink" : ({
         "NBExtensionApp" : {
             "symlink" : True,
         }}, "Create symlinks instead of copying files"
     ),
     "user" : ({
         "NBExtensionApp" : {
             "user" : True,
         }}, "Install to the user's IPython directory"
     ),
 }
 flags['s'] = flags['symlink']
 
 aliases = {
     "ipython-dir" : "NBExtensionApp.ipython_dir",
     "prefix" : "NBExtensionApp.prefix",
     "nbextensions" : "NBExtensionApp.nbextensions_dir",
 }
 
 class NBExtensionApp(BaseIPythonApplication):
     """Entry point for installing notebook extensions"""
     
     description = """Install IPython notebook extensions
     
     Usage
     
         ipython install-nbextension file [more files, folders, archives or urls]
     
     This copies files and/or folders into the IPython nbextensions directory.
     If a URL is given, it will be downloaded.
     If an archive is given, it will be extracted into nbextensions.
     If the requested files are already up to date, no action is taken
     unless --overwrite is specified.
     """
     
     examples = """
     ipython install-nbextension /path/to/d3.js /path/to/myextension
     """
     aliases = aliases
     flags = flags
     
     overwrite = Bool(False, config=True, help="Force overwrite of existing files")
     symlink = Bool(False, config=True, help="Create symlinks instead of copying files")
     user = Bool(False, config=True, help="Whether to do a user install")
     prefix = Unicode('', config=True, help="Installation prefix")
     nbextensions_dir = Unicode('', config=True, help="Full path to nbextensions dir (probably use prefix or user)")
     verbose = Enum((0,1,2), default_value=1, config=True,
         help="Verbosity level"
     )
     
     def install_extensions(self):
         install_nbextension(self.extra_args,
             overwrite=self.overwrite,
             symlink=self.symlink,
             verbose=self.verbose,
             user=self.user,
             prefix=self.prefix,
             nbextensions_dir=self.nbextensions_dir,
         )
     
     def start(self):
         if not self.extra_args:
             for nbext in [pjoin(self.ipython_dir, u'nbextensions')] + SYSTEM_NBEXTENSIONS_DIRS:
                 if os.path.exists(nbext):
                     print("Notebook extensions in %s:" % nbext)
                     for ext in os.listdir(nbext):
                         print(u"    %s" % ext)
         else:
             try:
                 self.install_extensions()
             except ArgumentConflict as e:
                 print(str(e), file=sys.stderr)
                 self.exit(1)
 
 
 if __name__ == '__main__':
     NBExtensionApp.launch_instance()
     
  No newline at end of file