demandimport: ignore `lzma` module for demandimport
This makes importing the module fail if the `_lzma` module is not present.
This makes e.g. tarfile correctly recognize if LZMA support is not present. It
changes the exception
File "/usr/lib/python3.6/tarfile.py", line 1694, in xzopen
fileobj = lzma.LZMAFile(fileobj or name, mode, preset=preset)
AttributeError: module 'lzma' has no attribute 'LZMAFile'
to the more correct exception
File "/usr/lib/python3.6/tarfile.py", line 1692, in xzopen
raise CompressionError("lzma module is not available")
tarfile.CompressionError: lzma module is not available
Also, it prevents that the error "abort: No module named '_lzma'!" is shown when
a development warning is to be shown. The reason why that happened is that for
showing the warning, we get information about the stack frames from the inspect
module, which accesses the `__file__` attribute of all modules in `sys.modules`
to build some cache, causing all modules (including `lzma`) to be imported.
# watchmanclient.py - Watchman client for the fsmonitor extension
#
# Copyright 2013-2016 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import getpass
from mercurial import (
encoding,
util,
)
from mercurial.utils import (
procutil,
stringutil,
)
from . import pywatchman
class Unavailable(Exception):
def __init__(self, msg, warn=True, invalidate=False):
self.msg = msg
self.warn = warn
if self.msg == b'timed out waiting for response':
self.warn = False
self.invalidate = invalidate
def __bytes__(self):
if self.warn:
return b'warning: Watchman unavailable: %s' % self.msg
else:
return b'Watchman unavailable: %s' % self.msg
__str__ = encoding.strmethod(__bytes__)
class WatchmanNoRoot(Unavailable):
def __init__(self, root, msg):
self.root = root
super(WatchmanNoRoot, self).__init__(msg)
class client(object):
def __init__(self, ui, root, timeout=1.0):
err = None
if not self._user:
err = b"couldn't get user"
warn = True
if self._user in ui.configlist(b'fsmonitor', b'blacklistusers'):
err = b'user %s in blacklist' % self._user
warn = False
if err:
raise Unavailable(err, warn)
self._timeout = timeout
self._watchmanclient = None
self._root = root
self._ui = ui
self._firsttime = True
def settimeout(self, timeout):
self._timeout = timeout
if self._watchmanclient is not None:
self._watchmanclient.setTimeout(timeout)
def getcurrentclock(self):
result = self.command(b'clock')
if not util.safehasattr(result, 'clock'):
raise Unavailable(
b'clock result is missing clock value', invalidate=True
)
return result.clock
def clearconnection(self):
self._watchmanclient = None
def available(self):
return self._watchmanclient is not None or self._firsttime
@util.propertycache
def _user(self):
try:
return getpass.getuser()
except KeyError:
# couldn't figure out our user
return None
def _command(self, *args):
watchmanargs = (args[0], self._root) + args[1:]
try:
if self._watchmanclient is None:
self._firsttime = False
watchman_exe = self._ui.configpath(
b'fsmonitor', b'watchman_exe'
)
self._watchmanclient = pywatchman.client(
timeout=self._timeout,
useImmutableBser=True,
binpath=procutil.tonativestr(watchman_exe),
)
return self._watchmanclient.query(*watchmanargs)
except pywatchman.CommandError as ex:
if 'unable to resolve root' in ex.msg:
raise WatchmanNoRoot(
self._root, stringutil.forcebytestr(ex.msg)
)
raise Unavailable(stringutil.forcebytestr(ex.msg))
except pywatchman.WatchmanError as ex:
raise Unavailable(stringutil.forcebytestr(ex))
def command(self, *args):
try:
try:
return self._command(*args)
except WatchmanNoRoot:
# this 'watch' command can also raise a WatchmanNoRoot if
# watchman refuses to accept this root
self._command(b'watch')
return self._command(*args)
except Unavailable:
# this is in an outer scope to catch Unavailable form any of the
# above _command calls
self._watchmanclient = None
raise