Synnefo

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# Utility functions

from synnefo.db.models import VirtualMachine

from synnefo.logic import credits

import synnefo.settings as settings

def id_from_instance_name(name):

    """Returns VirtualMachine's Django id, given a ganeti machine name.

    Strips the ganeti prefix atm. Needs a better name!

    """

    if not str(name).startswith(settings.BACKEND_PREFIX_ID):

        raise VirtualMachine.InvalidBackendIdError(str(name))

    ns = str(name).lstrip(settings.BACKEND_PREFIX_ID)

    if not ns.isdigit():

        raise VirtualMachine.InvalidBackendIdError(str(name))

    return int(ns)

def get_rsapi_state(vm):

    """Returns the API state for a virtual machine

    The API state for an instance of VirtualMachine is derived as follows:

    * If the deleted flag has been set, it is "DELETED".

    * Otherwise, it is a mapping of the last state reported by Ganeti

      (vm.operstate) through the RSAPI_STATE_FROM_OPER_STATE dictionary.

      The last state reported by Ganeti is set whenever Ganeti reports

      successful completion of an operation. If Ganeti says an OP_INSTANCE_STARTUP

      operation succeeded, vm.operstate is set to "STARTED".

    * To support any transitional states defined by the API (only REBOOT for the time

      being) this mapping is amended with information reported by Ganeti regarding

      any outstanding operation. If an OP_INSTANCE_STARTUP had succeeded previously

      and an OP_INSTANCE_REBOOT has been reported as in progress, the API state is

      "REBOOT".

    """

    try:

        r = VirtualMachine.RSAPI_STATE_FROM_OPER_STATE[vm.operstate]

    except KeyError:

        return "UNKNOWN"

    # A machine is DELETED if the deleted flag has been set

    if vm.deleted:

        return "DELETED"

    # A machine is in REBOOT if an OP_INSTANCE_REBOOT request is in progress

    if r == 'ACTIVE' and vm.backendopcode == 'OP_INSTANCE_REBOOT' and \

        vm.backendjobstatus in ('queued', 'waiting', 'running'):

        return "REBOOT"

    return r

def update_state(vm, new_operstate):

    """Wrapper around updates of the VirtualMachine.operstate field"""

    # Call charge() unconditionally before any change of

    # internal state.

    credits.charge(vm)

    vm.operstate = new_operstate