opcodes.py

#
#

# Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Google Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.


"""OpCodes module

This module implements the data structures which define the cluster
operations - the so-called opcodes.

Every operation which modifies the cluster state is expressed via
opcodes.

"""

# this are practically structures, so disable the message about too
# few public methods:
# pylint: disable-msg=R0903

import logging
import re

from ganeti import constants
from ganeti import errors
from ganeti import ht


# Common opcode attributes

#: output fields for a query operation
_POutputFields = ("output_fields", ht.NoDefault, ht.TListOf(ht.TNonEmptyString))

#: the shutdown timeout
_PShutdownTimeout = ("shutdown_timeout", constants.DEFAULT_SHUTDOWN_TIMEOUT,
                     ht.TPositiveInt)

#: the force parameter
_PForce = ("force", False, ht.TBool)

#: a required instance name (for single-instance LUs)
_PInstanceName = ("instance_name", ht.NoDefault, ht.TNonEmptyString)

#: Whether to ignore offline nodes
_PIgnoreOfflineNodes = ("ignore_offline_nodes", False, ht.TBool)

#: a required node name (for single-node LUs)
_PNodeName = ("node_name", ht.NoDefault, ht.TNonEmptyString)

#: a required node group name (for single-group LUs)
_PGroupName = ("group_name", ht.NoDefault, ht.TNonEmptyString)

#: Migration type (live/non-live)
_PMigrationMode = ("mode", None,
                   ht.TOr(ht.TNone, ht.TElemOf(constants.HT_MIGRATION_MODES)))

#: Obsolete 'live' migration mode (boolean)
_PMigrationLive = ("live", None, ht.TMaybeBool)

#: Tag type
_PTagKind = ("kind", ht.NoDefault, ht.TElemOf(constants.VALID_TAG_TYPES))

#: List of tag strings
_PTags = ("tags", ht.NoDefault, ht.TListOf(ht.TNonEmptyString))

#: OP_ID conversion regular expression
_OPID_RE = re.compile("([a-z])([A-Z])")


def _NameToId(name):
  """Convert an opcode class name to an OP_ID.

  @type name: string
  @param name: the class name, as OpXxxYyy
  @rtype: string
  @return: the name in the OP_XXXX_YYYY format

  """
  if not name.startswith("Op"):
    return None
  # Note: (?<=[a-z])(?=[A-Z]) would be ideal, since it wouldn't
  # consume any input, and hence we would just have all the elements
  # in the list, one by one; but it seems that split doesn't work on
  # non-consuming input, hence we have to process the input string a
  # bit
  name = _OPID_RE.sub(r"\1,\2", name)
  elems = name.split(",")
  return "_".join(n.upper() for n in elems)


def RequireFileStorage():
  """Checks that file storage is enabled.

  While it doesn't really fit into this module, L{utils} was deemed too large
  of a dependency to be imported for just one or two functions.

  @raise errors.OpPrereqError: when file storage is disabled

  """
  if not constants.ENABLE_FILE_STORAGE:
    raise errors.OpPrereqError("File storage disabled at configure time",
                               errors.ECODE_INVAL)


def RequireSharedFileStorage():
  """Checks that shared file storage is enabled.

  While it doesn't really fit into this module, L{utils} was deemed too large
  of a dependency to be imported for just one or two functions.

  @raise errors.OpPrereqError: when shared file storage is disabled

  """
  if not constants.ENABLE_SHARED_FILE_STORAGE:
    raise errors.OpPrereqError("Shared file storage disabled at"
                               " configure time", errors.ECODE_INVAL)


def _CheckDiskTemplate(template):
  """Ensure a given disk template is valid.

  """
  if template not in constants.DISK_TEMPLATES:
    # Using str.join directly to avoid importing utils for CommaJoin
    msg = ("Invalid disk template name '%s', valid templates are: %s" %
           (template, ", ".join(constants.DISK_TEMPLATES)))
    raise errors.OpPrereqError(msg, errors.ECODE_INVAL)
  if template == constants.DT_FILE:
    RequireFileStorage()
  elif template == constants.DT_SHARED_FILE:
    RequireSharedFileStorage()
  return True


def _CheckStorageType(storage_type):
  """Ensure a given storage type is valid.

  """
  if storage_type not in constants.VALID_STORAGE_TYPES:
    raise errors.OpPrereqError("Unknown storage type: %s" % storage_type,
                               errors.ECODE_INVAL)
  if storage_type == constants.ST_FILE:
    RequireFileStorage()
  return True


#: Storage type parameter
_PStorageType = ("storage_type", ht.NoDefault, _CheckStorageType)


class _AutoOpParamSlots(type):
  """Meta class for opcode definitions.

  """
  def __new__(mcs, name, bases, attrs):
    """Called when a class should be created.

    @param mcs: The meta class
    @param name: Name of created class
    @param bases: Base classes
    @type attrs: dict
    @param attrs: Class attributes

    """
    assert "__slots__" not in attrs, \
      "Class '%s' defines __slots__ when it should use OP_PARAMS" % name
    assert "OP_ID" not in attrs, "Class '%s' defining OP_ID" % name

    attrs["OP_ID"] = _NameToId(name)

    # Always set OP_PARAMS to avoid duplicates in BaseOpCode.GetAllParams
    params = attrs.setdefault("OP_PARAMS", [])

    # Use parameter names as slots
    slots = [pname for (pname, _, _) in params]

    assert "OP_DSC_FIELD" not in attrs or attrs["OP_DSC_FIELD"] in slots, \
      "Class '%s' uses unknown field in OP_DSC_FIELD" % name

    attrs["__slots__"] = slots

    return type.__new__(mcs, name, bases, attrs)


class BaseOpCode(object):