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"""Common functions used by multiple logical units."""

from ganeti import errors

from ganeti import locking

from ganeti import utils

def _ExpandItemName(fn, name, kind):

  """Expand an item name.

  @param fn: the function to use for expansion

  @param name: requested item name

  @param kind: text description ('Node' or 'Instance')

  @return: the resolved (full) name

  @raise errors.OpPrereqError: if the item is not found

  """

  full_name = fn(name)

  if full_name is None:

    raise errors.OpPrereqError("%s '%s' not known" % (kind, name),

                               errors.ECODE_NOENT)

  return full_name

def _ExpandInstanceName(cfg, name):

  """Wrapper over L{_ExpandItemName} for instance."""

  return _ExpandItemName(cfg.ExpandInstanceName, name, "Instance")

def _ExpandNodeName(cfg, name):

  """Wrapper over L{_ExpandItemName} for nodes."""

  return _ExpandItemName(cfg.ExpandNodeName, name, "Node")

def _ShareAll():

  """Returns a dict declaring all lock levels shared.

  """

  return dict.fromkeys(locking.LEVELS, 1)

def _CheckNodeGroupInstances(cfg, group_uuid, owned_instances):

  """Checks if the instances in a node group are still correct.

  @type cfg: L{config.ConfigWriter}

  @param cfg: The cluster configuration

  @type group_uuid: string

  @param group_uuid: Node group UUID

  @type owned_instances: set or frozenset

  @param owned_instances: List of currently owned instances

  """

  wanted_instances = cfg.GetNodeGroupInstances(group_uuid)

  if owned_instances != wanted_instances:

    raise errors.OpPrereqError("Instances in node group '%s' changed since"

                               " locks were acquired, wanted '%s', have '%s';"

                               " retry the operation" %

                               (group_uuid,

                                utils.CommaJoin(wanted_instances),

                                utils.CommaJoin(owned_instances)),

                               errors.ECODE_STATE)

  return wanted_instances