mirror of
git://sourceware.org/git/lvm2.git
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e53454d6de
We need to place query operations in the queue to prevent the case where a client knows of something before the service does. For example if a client creates a PV/VG/LV outside of the dbus API and then immediately tries to lookup and use that resource in the lvm dbus service it should be present. By placing the queries in the work queue any previous refresh operation will complete before we process the query.
384 lines
12 KiB
Python
384 lines
12 KiB
Python
# Copyright (C) 2015-2016 Red Hat, Inc. All rights reserved.
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#
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# This copyrighted material is made available to anyone wishing to use,
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# modify, copy, or redistribute it subject to the terms and conditions
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# of the GNU General Public License v.2.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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import sys
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import threading
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import traceback
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import dbus
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import os
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import copy
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from . import cfg
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from .utils import log_debug, pv_obj_path_generate, log_error
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from .automatedproperties import AutomatedProperties
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# noinspection PyPep8Naming
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class ObjectManager(AutomatedProperties):
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"""
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Implements the org.freedesktop.DBus.ObjectManager interface
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"""
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def __init__(self, object_path, interface):
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super(ObjectManager, self).__init__(object_path, interface)
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self.set_interface(interface)
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self._ap_o_path = object_path
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self._objects = {}
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self._id_to_object_path = {}
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self.rlock = threading.RLock()
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@staticmethod
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def _get_managed_objects(obj):
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with obj.rlock:
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rc = {}
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try:
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for k, v in list(obj._objects.items()):
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path, props = v[0].emit_data()
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rc[path] = props
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except Exception:
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traceback.print_exc(file=sys.stdout)
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sys.exit(1)
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return rc
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@dbus.service.method(
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dbus_interface="org.freedesktop.DBus.ObjectManager",
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out_signature='a{oa{sa{sv}}}', async_callbacks=('cb', 'cbe'))
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def GetManagedObjects(self, cb, cbe):
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r = cfg.create_request_entry(-1, ObjectManager._get_managed_objects,
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(self, ), cb, cbe, False)
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cfg.worker_q.put(r)
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def locked(self):
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"""
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If some external code need to run across a number of different
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calls into ObjectManager while blocking others they can use this method
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to lock others out.
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:return:
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"""
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return ObjectManagerLock(self.rlock)
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@dbus.service.signal(
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dbus_interface="org.freedesktop.DBus.ObjectManager",
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signature='oa{sa{sv}}')
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def InterfacesAdded(self, object_path, int_name_prop_dict):
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log_debug(
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('SIGNAL: InterfacesAdded(%s, %s)' %
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(str(object_path), str(int_name_prop_dict))))
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@dbus.service.signal(
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dbus_interface="org.freedesktop.DBus.ObjectManager",
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signature='oas')
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def InterfacesRemoved(self, object_path, interface_list):
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log_debug(('SIGNAL: InterfacesRemoved(%s, %s)' %
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(str(object_path), str(interface_list))))
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def validate_lookups(self):
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with self.rlock:
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tmp_lookups = copy.deepcopy(self._id_to_object_path)
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# iterate over all we know, removing from the copy. If all is well
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# we will have zero items left over
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for path, md in self._objects.items():
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obj, lvm_id, uuid = md
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if lvm_id:
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assert path == tmp_lookups[lvm_id]
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del tmp_lookups[lvm_id]
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if uuid:
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assert path == tmp_lookups[uuid]
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del tmp_lookups[uuid]
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rc = len(tmp_lookups)
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if rc:
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# Error condition
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log_error("_id_to_object_path has extraneous lookups!")
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for key, path in tmp_lookups.items():
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log_error("Key= %s, path= %s" % (key, path))
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return rc
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def _lookup_add(self, obj, path, lvm_id, uuid):
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"""
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Store information about what we added to the caches so that we
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can remove it cleanly
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:param obj: The dbus object we are storing
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:param lvm_id: The lvm id for the asset
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:param uuid: The uuid for the asset
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:return:
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"""
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# Note: Only called internally, lock implied
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# We could have a temp entry from the forward creation of a path
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self._lookup_remove(path)
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self._objects[path] = (obj, lvm_id, uuid)
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# Make sure we have one or the other
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assert lvm_id or uuid
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if lvm_id:
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self._id_to_object_path[lvm_id] = path
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if uuid:
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self._id_to_object_path[uuid] = path
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def _lookup_remove(self, obj_path):
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# Note: Only called internally, lock implied
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if obj_path in self._objects:
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(obj, lvm_id, uuid) = self._objects[obj_path]
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if lvm_id in self._id_to_object_path:
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del self._id_to_object_path[lvm_id]
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if uuid in self._id_to_object_path:
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del self._id_to_object_path[uuid]
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del self._objects[obj_path]
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def lookup_update(self, dbus_obj, new_uuid, new_lvm_id):
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with self.rlock:
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obj_path = dbus_obj.dbus_object_path()
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self._lookup_remove(obj_path)
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self._lookup_add(
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dbus_obj, obj_path,
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new_lvm_id, new_uuid)
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def object_paths_by_type(self, o_type):
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with self.rlock:
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rc = {}
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for k, v in list(self._objects.items()):
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if isinstance(v[0], o_type):
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rc[k] = True
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return rc
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def register_object(self, dbus_object, emit_signal=False):
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"""
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Given a dbus object add it to the collection
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:param dbus_object: Dbus object to register
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:param emit_signal: If true emit a signal for interfaces added
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"""
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with self.rlock:
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path, props = dbus_object.emit_data()
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# print('Registering object path %s for %s' %
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# (path, dbus_object.lvm_id))
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# We want fast access to the object by a number of different ways
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# so we use multiple hashs with different keys
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self._lookup_add(dbus_object, path, dbus_object.lvm_id,
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dbus_object.Uuid)
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if emit_signal:
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self.InterfacesAdded(path, props)
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def remove_object(self, dbus_object, emit_signal=False):
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"""
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Given a dbus object, remove it from the collection and remove it
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from the dbus framework as well
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:param dbus_object: Dbus object to remove
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:param emit_signal: If true emit the interfaces removed signal
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"""
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with self.rlock:
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# Store off the object path and the interface first
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path = dbus_object.dbus_object_path()
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interfaces = dbus_object.interface()
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# print 'UN-Registering object path %s for %s' % \
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# (path, dbus_object.lvm_id)
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self._lookup_remove(path)
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# Remove from dbus library
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dbus_object.remove_from_connection(cfg.bus, path)
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# Optionally emit a signal
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if emit_signal:
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self.InterfacesRemoved(path, interfaces)
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def get_object_by_path(self, path):
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"""
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Given a dbus path return the object registered for it
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:param path: The dbus path
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:return: The object
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"""
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with self.rlock:
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if path in self._objects:
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return self._objects[path][0]
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return None
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def get_object_by_uuid_lvm_id(self, uuid, lvm_id):
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with self.rlock:
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return self.get_object_by_path(
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self.get_object_path_by_uuid_lvm_id(uuid, lvm_id))
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def get_object_by_lvm_id(self, lvm_id):
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"""
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Given an lvm identifier, return the object registered for it
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:param lvm_id: The lvm identifier
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"""
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with self.rlock:
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if lvm_id in self._id_to_object_path:
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return self.get_object_by_path(self._id_to_object_path[lvm_id])
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return None
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def get_object_path_by_lvm_id(self, lvm_id):
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"""
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Given an lvm identifier, return the object path for it
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:param lvm_id: The lvm identifier
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:return: Object path or '/' if not found
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"""
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with self.rlock:
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if lvm_id in self._id_to_object_path:
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return self._id_to_object_path[lvm_id]
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return '/'
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def _uuid_verify(self, path, uuid, lvm_id):
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"""
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Ensure uuid is present for a successful lvm_id lookup
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NOTE: Internal call, assumes under object manager lock
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:param path: Path to object we looked up
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:param uuid: lvm uuid to verify
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:param lvm_id: lvm_id used to find object
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:return: None
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"""
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# This gets called when we found an object based on lvm_id, ensure
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# uuid is correct too, as they can change. There is no durable
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# non-changeable name in lvm
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if lvm_id != uuid:
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if uuid and uuid not in self._id_to_object_path:
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obj = self.get_object_by_path(path)
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self._lookup_add(obj, path, lvm_id, uuid)
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def _lvm_id_verify(self, path, uuid, lvm_id):
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"""
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Ensure lvm_id is present for a successful uuid lookup
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NOTE: Internal call, assumes under object manager lock
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:param path: Path to object we looked up
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:param uuid: uuid used to find object
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:param lvm_id: lvm_id to verify
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:return: None
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"""
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# This gets called when we found an object based on uuid, ensure
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# lvm_id is correct too, as they can change. There is no durable
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# non-changeable name in lvm
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if lvm_id != uuid:
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if lvm_id and lvm_id not in self._id_to_object_path:
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obj = self.get_object_by_path(path)
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self._lookup_add(obj, path, lvm_id, uuid)
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def _id_lookup(self, the_id):
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path = None
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if the_id:
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# The _id_to_object_path contains hash keys for everything, so
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# uuid and lvm_id
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if the_id in self._id_to_object_path:
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path = self._id_to_object_path[the_id]
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else:
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if "/" in the_id:
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if the_id.startswith('/'):
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# We could have a pv device path lookup that failed,
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# lets try canonical form and try again.
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canonical = os.path.realpath(the_id)
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if canonical in self._id_to_object_path:
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path = self._id_to_object_path[canonical]
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else:
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vg, lv = the_id.split("/", 1)
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int_lvm_id = vg + "/" + ("[%s]" % lv)
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if int_lvm_id in self._id_to_object_path:
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path = self._id_to_object_path[int_lvm_id]
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return path
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def get_object_path_by_uuid_lvm_id(self, uuid, lvm_id, path_create=None):
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"""
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For a given lvm asset return the dbus object path registered for it.
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This method first looks up by uuid and then by lvm_id. You
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can search by just one by setting uuid == lvm_id (uuid or lvm_id).
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If the object is not found and path_create is a not None, the
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path_create function will be called to create a new object path and
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register it with the object manager for the specified uuid & lvm_id.
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Note: If path create is not None, uuid and lvm_id cannot be equal
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:param uuid: The uuid for the lvm object we are searching for
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:param lvm_id: The lvm name (eg. pv device path, vg name, lv full name)
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:param path_create: If not None, create the path using this function if
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we fail to find the object by uuid or lvm_id.
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:returns None if lvm asset not found and path_create == None otherwise
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a valid dbus object path
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"""
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with self.rlock:
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assert lvm_id
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assert uuid
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if path_create:
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assert uuid != lvm_id
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# Check for Manager.LookUpByLvmId query, we cannot
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# check/verify/update the uuid and lvm_id lookups so don't!
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if uuid == lvm_id:
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path = self._id_lookup(lvm_id)
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else:
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# We have a uuid and a lvm_id we can do sanity checks to ensure
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# that they are consistent
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# If a PV is missing it's device path is '[unknown]' or some
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# other text derivation of unknown. When we find that a PV is
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# missing we will clear out the lvm_id as it's likely not unique
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# and thus not useful and potentially harmful for lookups.
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if path_create == pv_obj_path_generate and \
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cfg.db.pv_missing(uuid):
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lvm_id = None
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# Lets check for the uuid first
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path = self._id_lookup(uuid)
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if path:
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# Verify the lvm_id is sane
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self._lvm_id_verify(path, uuid, lvm_id)
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else:
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# Unable to find by UUID, lets lookup by lvm_id
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path = self._id_lookup(lvm_id)
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if path:
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# Verify the uuid is sane
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self._uuid_verify(path, uuid, lvm_id)
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else:
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# We have exhausted all lookups, let's create if we can
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if path_create:
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path = path_create()
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self._lookup_add(None, path, lvm_id, uuid)
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# print('get_object_path_by_lvm_id(%s, %s, %s, %s: return %s' %
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# (uuid, lvm_id, str(path_create), str(gen_new), path))
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return path
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class ObjectManagerLock(object):
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"""
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The sole purpose of this class is to allow other code the ability to
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lock the object manager using a `with` statement, eg.
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with cfg.om.locked():
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# Do stuff with object manager
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This will ensure that the lock is always released (assuming this is done
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correctly)
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"""
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def __init__(self, recursive_lock):
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self._lock = recursive_lock
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def __enter__(self):
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# Acquire lock
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self._lock.acquire()
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# noinspection PyUnusedLocal
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def __exit__(self, e_type, e_value, e_traceback):
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# Release lock
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self._lock.release()
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self._lock = None
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