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#

# Copyright (C) 2013 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.

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# 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.

"""Utility functions for storage.

"""

import logging

from ganeti import constants

def GetDiskTemplatesOfStorageType(storage_type):

  """Given the storage type, returns a list of disk templates based on that

     storage type."""

  return [dt for dt in constants.DISK_TEMPLATES

          if constants.MAP_DISK_TEMPLATE_STORAGE_TYPE[dt] == storage_type]

def IsDiskTemplateEnabled(disk_template, enabled_disk_templates):

  """Checks if a particular disk template is enabled.

  """

  return disk_template in enabled_disk_templates

def IsFileStorageEnabled(enabled_disk_templates):

  """Checks if file storage is enabled.

  """

  return IsDiskTemplateEnabled(constants.DT_FILE, enabled_disk_templates)

def IsSharedFileStorageEnabled(enabled_disk_templates):

  """Checks if shared file storage is enabled.

  """

  return IsDiskTemplateEnabled(constants.DT_SHARED_FILE, enabled_disk_templates)

def IsLvmEnabled(enabled_disk_templates):

  """Check whether or not any lvm-based disk templates are enabled."""

  return len(constants.DTS_LVM & set(enabled_disk_templates)) != 0

def LvmGetsEnabled(enabled_disk_templates, new_enabled_disk_templates):

  """Checks whether lvm was not enabled before, but will be enabled after

     the operation.

  """

  if IsLvmEnabled(enabled_disk_templates):

    return False

  return len(constants.DTS_LVM & set(new_enabled_disk_templates)) != 0

def _GetDefaultStorageUnitForDiskTemplate(cfg, disk_template):

  """Retrieves the identifier of the default storage entity for the given

  storage type.

  @type cfg: C{objects.ConfigData}

  @param cfg: the configuration data

  @type disk_template: string

  @param disk_template: a disk template, for example 'drbd'

  @rtype: string

  @return: identifier for a storage unit, for example the vg_name for lvm

     storage

  """

  storage_type = constants.MAP_DISK_TEMPLATE_STORAGE_TYPE[disk_template]

  cluster = cfg.GetClusterInfo()

  if disk_template in constants.DTS_LVM:

    return (storage_type, cfg.GetVGName())

  elif disk_template == constants.DT_FILE:

    return (storage_type, cluster.file_storage_dir)

  elif disk_template == constants.DT_SHARED_FILE:

    return (storage_type, cluster.shared_file_storage_dir)

  else:

    return (storage_type, None)

def DiskTemplateSupportsSpaceReporting(disk_template):

  """Check whether the disk template supports storage space reporting."""

  return (constants.MAP_DISK_TEMPLATE_STORAGE_TYPE[disk_template]

          in constants.STS_REPORT)

def GetStorageUnits(cfg, disk_templates):

  """Get the cluster's storage units for the given disk templates.

  If any lvm-based disk template is requested, spindle information

  is added to the request.

  @type cfg: L{config.ConfigWriter}

  @param cfg: Cluster configuration

  @type disk_templates: list of string

  @param disk_templates: list of disk templates for which the storage

    units will be computed

  @rtype: list of tuples (string, string)

  @return: list of storage units, each storage unit being a tuple of

    (storage_type, storage_key); storage_type is in

    C{constants.STORAGE_TYPES} and the storage_key a string to

    identify an entity of that storage type, for example a volume group

    name for LVM storage or a file for file storage.

  """

  storage_units = []

  for disk_template in disk_templates:

    if DiskTemplateSupportsSpaceReporting(disk_template):

      storage_units.append(

          _GetDefaultStorageUnitForDiskTemplate(cfg, disk_template))

  return storage_units

def LookupSpaceInfoByDiskTemplate(storage_space_info, disk_template):

  """Looks up the storage space info for a given disk template.

  @type storage_space_info: list of dicts

  @param storage_space_info: result of C{GetNodeInfo}

  @type disk_template: string

  @param disk_template: disk template to get storage space info

  @rtype: tuple

  @return: returns the element of storage_space_info that matches the given

    disk template

  """

  storage_type = constants.MAP_DISK_TEMPLATE_STORAGE_TYPE[disk_template]

  return LookupSpaceInfoByStorageType(storage_space_info, storage_type)

def LookupSpaceInfoByStorageType(storage_space_info, storage_type):

  """Looks up the storage space info for a given storage type.

  Note that this lookup can be ambiguous if storage space reporting for several

  units of the same storage type was requested. This function is only supposed

  to be used for legacy code in situations where it actually is unambiguous.

  @type storage_space_info: list of dicts

  @param storage_space_info: result of C{GetNodeInfo}

  @type storage_type: string

  @param storage_type: a storage type, which is included in the storage_units

    list

  @rtype: tuple

  @return: returns the element of storage_space_info that matches the given

    storage type

  """

  result = None

  for unit_info in storage_space_info:

    if unit_info["type"] == storage_type:

      if result is None:

        result = unit_info

      else:

        # There is more than one storage type in the query, log a warning

        logging.warning("Storage space information requested for"

                        " ambiguous storage type '%s'.", storage_type)

  return result