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# -*- coding: utf-8 -*-
"""
pyxs._compat
~~~~~~~~~~~~
This module implements compatibility interface for scripts,
using ``xen.lowlevel.xs``.
:copyright: (c) 2011 by Selectel.
:copyright: (c) 2016 by pyxs authors and contributors, see AUTHORS
for more details.
:license: LGPL, see LICENSE for more details.
"""
from __future__ import absolute_import
__all__ = ["xs", "Error"]
import errno
from .client import Client
from .exceptions import PyXSError as Error
class xs(object):
"""XenStore client with a backward compatible interface, useful for
switching from ``xen.lowlevel.xs``.
"""
def __init__(self):
self.client = Client()
self.client.connect()
self.monitor = self.client.monitor()
self.token_aliases = {}
def close(self):
self.client.close()
def get_permissions(self, tx_id, path):
self.client.tx_id = int(tx_id or 0)
self.client.get_perms(path)
def set_permissions(self, tx_id, path, perms):
self.client.tx_id = int(tx_id or 0)
self.client.set_perms(path, perms)
def ls(self, tx_id, path):
self.client.tx_id = int(tx_id or 0)
try:
return self.client.list(path)
except Error as e:
if e.args[0] == errno.ENOENT:
return
raise
def mkdir(self, tx_id, path):
self.client.tx_id = int(tx_id or 0)
self.client.mkdir(path)
def rm(self, tx_id, path):
self.client.tx_id = int(tx_id or 0)
self.client.delete(path)
def read(self, tx_id, path):
self.client.tx_id = int(tx_id or 0)
return self.client.read(path)
def write(self, tx_id, path, value):
self.client.tx_id = int(tx_id or 0)
return self.client.write(path, value)
def get_domain_path(self, domid):
return self.client.get_domain_path(domid)
def introduce_domain(self, domid, mfn, eventchn):
self.client.introduce_domain(domid, mfn, eventchn)
def release_domain(self, domid):
self.client.release_domain(domid)
def resume_domain(self, domid):
self.client.resume_domain(domid)
def set_target(self, domid, target):
self.client.set_target(domid, target)
def transaction_start(self):
return str(self.client.transaction()).encode()
def transaction_end(self, tx_id, abort=0):
self.client.tx_id = int(tx_id or 0)
if abort:
self.client.rollback()
else:
try:
self.client.commit()
except Error as e:
if e.args[0] == errno.EAGAIN:
return False
raise
return True
def watch(self, path, token):
# Even though ``xs.watch`` docstring states that token should be
# a string, it in fact can be any Python object. We mimic this
# behaviour here, but it can be a source of hard to find bugs.
# See http://lists.xen.org/archives/html/xen-devel/2016-03/msg00228
# for discussion.
stub = str(id(token)).encode()
self.token_aliases[stub] = token
return self.monitor.watch(path, stub)
def unwatch(self, path, token):
stub = str(id(token)).encode()
self.monitor.unwatch(path, stub)
del self.token_aliases[stub]
def read_watch(self):
event = next(self.monitor.wait())
return event._replace(token=self.token_aliases[event.token])
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