__init__.py

import logging
import weakref
from StringIO import StringIO
from itertools import chain, imap
from xml.etree import cElementTree as et

import libvirt
from sjrpc.utils import threadless

from cloudcontrol.node.host import Handler as HostHandler
from cloudcontrol.node.tags import Tag, tag_inspector, get_tags
from cloudcontrol.node.hypervisor import tags
from cloudcontrol.node.hypervisor.lib import (
    DOMAIN_STATES, EVENTS, STORAGE_STATES,
    EventLoop as VirEventLoop,
)
from cloudcontrol.node.hypervisor.domains import VirtualMachine
from cloudcontrol.node.exc import UndefinedDomain, PoolStorageError, DRBDError
from cloudcontrol.node.hypervisor.jobs import (
    ImportVolume, ExportVolume, TCPTunnel, DRBD,
)


logger = logging.getLogger(__name__)


# FIXME find a way to refactor Handler and Hypervisor class
class Handler(HostHandler):
    def __init__(self, *args, **kwargs):
        """
        :param loop: MainLoop instance
        :param hypervisor_name: hypervisor name
        """
        self.hypervisor_name = kwargs.pop('hypervisor_name')
        HostHandler.__init__(self, *args, **kwargs)

        #: keep index of asynchronous calls
        self.async_calls = dict()

        self.timer = self.main.evloop.timer(.0, 5., self.virt_connect_cb)
        self.hypervisor = None
        self._virt_connected = False

        # register tags
        self.tag_db.add_tags(tag_inspector(tags, self))

    @property
    def virt_connected(self):
        return self._virt_connected

    @virt_connected.setter
    def virt_connected(self, value):
        self._virt_connected = value
        # update tags
        for tag in ('vir_status', 'sto', 'nvm', 'vmpaused', 'vmstarted',
                    'vmstopped', 'hvver', 'libvirtver', 'hv'):
            self.tag_db['__main__'][tag].update_value()

    def start(self):
        self.timer.start()
        HostHandler.start(self)

    def stop(self):
        self.timer.stop()
        if self.hypervisor is not None:
            self.hypervisor.stop()
        HostHandler.stop(self)

    def virt_connect_cb(self, *args):
        # initialize hypervisor instance
        try:
            self.hypervisor = Hypervisor(
                name=self.hypervisor_name,
                handler=self,
            )
        except libvirt.libvirtError:
            logger.exception('Error while connecting to libvirt')
            return

        self.virt_connected = True

        # register hypervisor storage tags
        for name, storage in self.hypervisor.storage.storages.iteritems():
            self.tag_db.add_tags((
                Tag('sto%s_state' % name, lambda: storage.state, 5, 5),
                Tag('sto%s_size' % name, lambda: storage.capacity, 5, 5),
                Tag('sto%s_free' % name, lambda: storage.available, 5, 5),
                Tag('sto%s_used' % name,
                    lambda: storage.capacity - storage.available, 5, 5),
                Tag('sto%s_type' % name, lambda: storage.type, 5, 5),
            ))

        # register domains
        for dom in self.hypervisor.domains.itervalues():
            self.tag_db.add_sub_object(dom.name, dom.tags.itervalues())

        self.rpc_handler.update(dict(
            vm_define=self.vm_define,
            vm_undefine=self.vm_undefine,
            vm_export=self.vm_export,
            vm_stop=self.vm_stop,
            vm_start=self.vm_start,
            vm_suspend=self.vm_suspend,
            vm_resume=self.vm_resume,
        ))
        self.main.reset_handler('vm_define', self.vm_define)
        self.main.reset_handler('vm_undefine', self.vm_undefine)
        self.main.reset_handler('vm_export', self.vm_export)
        self.main.reset_handler('vm_stop', self.vm_stop)
        self.main.reset_handler('vm_destroy', self.vm_destroy)
        self.main.reset_handler('vm_start', self.vm_start)
        self.main.reset_handler('vm_suspend', self.vm_suspend)
        self.main.reset_handler('vm_resume', self.vm_resume)
        self.main.reset_handler('vm_migrate_tunneled', self.vm_migrate_tunneled)
        self.main.reset_handler('vol_create', self.vol_create)
        self.main.reset_handler('vol_delete', self.vol_delete)
        self.main.reset_handler('vol_import', self.vol_import)
        self.main.reset_handler('vol_import_wait', self.vol_import_wait)
        self.main.reset_handler('vol_export', self.vol_export)
        self.main.reset_handler('tun_setup', self.tun_setup)
        self.main.reset_handler('tun_connect', self.tun_connect)
        self.main.reset_handler('tun_connect_hv', self.tun_connect_hv)
        self.main.reset_handler('tun_destroy', self.tun_destroy)
        self.main.reset_handler('drbd_setup', self.drbd_setup)
        self.main.reset_handler('drbd_connect', self.drbd_connect)
        self.main.reset_handler('drbd_role', self.drbd_role)
        self.main.reset_handler('drbd_takeover', self.drbd_takeover)
        self.main.reset_handler('drbd_sync_status', self.drbd_sync_status)
        self.main.reset_handler('drbd_shutdown', self.drbd_shutdown)

        # if everything went fine, unregister the timer
        self.timer.stop()

    def virt_connect_restart(self):
        """Restart libvirt connection.

        This method might be called when libvirt connection is lost.
        """
        if not self.virt_connected:
            return

        logger.error('Connection to libvirt lost, trying to restart')
        # update connection state
        self.virt_connected = False
        # unregister tags that will be re registered later
        for storage in self.hypervisor.storage.storages:
            self.tag_db.remove_tags((
                'sto%s_state' % storage,
                'sto%s_size' % storage,
                'sto%s_free' % storage,
                'sto%s_used' % storage,
                'sto%s_type' % storage,
            ))
        # unregister sub objects (for the same reason)
        for sub_id in self.tag_db.keys():
            if sub_id == '__main__':
                continue
            self.tag_db.remove_sub_object(sub_id)
        # stop and delete hypervisor instance
        self.hypervisor.stop()
        self.hypervisor = None

        # remove handlers related to libvirt
        self.main.remove_handler('vm_define')
        self.main.remove_handler('vm_undefine')
        self.main.remove_handler('vm_export')
        self.main.remove_handler('vm_stop')
        self.main.remove_handler('vm_destroy')
        self.main.remove_handler('vm_start')
        self.main.remove_handler('vm_suspend')
        self.main.remove_handler('vm_resume')
        self.main.remove_handler('vm_migrate_tunneled')
        self.main.remove_handler('vol_create')
        self.main.remove_handler('vol_delete')
        self.main.remove_handler('vol_import')
        self.main.remove_handler('vol_import_wait')
        self.main.remove_handler('vol_export')
        self.main.remove_handler('tun_setup')
        self.main.remove_handler('tun_connect')
        self.main.remove_handler('tun_connect_hv')
        self.main.remove_handler('tun_destroy')
        self.main.remove_handler('drbd_setup')
        self.main.remove_handler('drbd_connect')
        self.main.remove_handler('drbd_role')
        self.main.remove_handler('drbd_takeover')
        self.main.remove_handler('drbd_sync_status')
        self.main.remove_handler('drbd_shutdown')
        # launch connection timer
        self.timer.start()

    def iter_vms(self, vm_names):
        """Utility function to iterate over VM objects using their names."""
        if vm_names is None:
            return
        get_domain = self.hypervisor.domains.get
        for name in vm_names:
            dom = get_domain(name)
            if dom is not None:
                yield dom

    def vm_define(self, data, format='xml'):
        logger.debug('VM define')
        if format != 'xml':
            raise NotImplementedError('Format not supported')

        return self.hypervisor.vm_define(data)

    def vm_undefine(self, name):
        logger.debug('VM undefine %s', name)
        vm = self.hypervisor.domains.get(name)
        if vm is not None:
            vm.undefine()

    def vm_export(self, name, format='xml'):
        logger.debug('VM export %s', name)
        if format != 'xml':
            raise NotImplementedError('Format not supported')

        vm = self.hypervisor.domains.get(name)

        if vm is None:
            return

        return vm.lv_dom.XMLDesc(0)

    def vm_stop(self, name):
        logger.debug('VM stop %s', name)
        try:
            self.hypervisor.domains[name].stop()
        except libvirt.libvirtError:
            logger.exception('Error while stopping VM %s', name)
            raise
        except KeyError:
            msg = 'Cannot stop VM %s because it is not defined' % name
            logger.error(msg)
            raise UndefinedDomain(msg)

    def vm_destroy(self, name):
        logger.debug('VM destroy %s', name)
        try:
            self.hypervisor.domains[name].destroy()
        except libvirt.libvirtError as exc:
            # Libvirt raises exception 'domain is not running' event is domain
            # is running, might be a bug in libvirt
            if 'domain is not running' not in str(exc) or (
                self.hypervisor.domains[name].state != 'running'):
                logger.exception('Error while destroying VM %s', name)
                raise
        except KeyError:
            msg = 'Cannot destroy VM %s because it is not defined' % name
            logger.error(msg)
            raise UndefinedDomain(msg)

    def vm_start(self, name):
        logger.debug('VM start %s', name)
        try:
            self.hypervisor.domains[name].start()
        except libvirt.libvirtError:
            logger.exception('Error while starting VM %s', name)
            raise
        except KeyError:
            msg = 'Cannot start VM %s because it is not defined' % name
            logger.error(msg)
            raise UndefinedDomain(msg)

    def vm_suspend(self, name):
        logger.debug('VM suspend %s', name)
        try:
            self.hypervisor.domains[name].suspend()
        except libvirt.libvirtError:
            logger.exception('Error while suspending VM %s', name)
            raise
        except KeyError:
            msg = 'Cannot suspend VM %s because it is not defined' % name
            logger.error(msg)
            raise UndefinedDomain(msg)

    def vm_resume(self, name):
        logger.debug('VM resume %s', name)
        try:
            self.hypervisor.domains[name].resume()
        except libvirt.libvirtError:
            logger.exception('Error while resuming VM %s', name)
            raise
        except KeyError:
            msg = 'Cannot resume VM %s because it is not defined' % name
            logger.error(msg)
            raise UndefinedDomain(msg)

    def vm_migrate_tunneled(self, name, tun_res, migtun_res, unsafe=False):
        """Live migrate VM through TCP tunnel.

        :param name: VM name to migrate
        :param tun_res: result of tunnel_setup handler
        :param migtun_res: result of tunnel setup handler
        :param unsafe: for Libvirt >= 0.9.11, see
            http://libvirt.org/html/libvirt-libvirt.html#virDomainMigrateFlags
        """
        logger.debug('VM live migrate %s', name)

        try:
            remote_virt_port = tun_res['port']
        except KeyError:
            logger.error('Invalid formatted argument tun_res for live'
                         ' migration')
            raise
        try:
            remote_hv_port = migtun_res['port']
        except KeyError:
            logger.error('Invalid formatted argument migtun_res for live'
                         ' migration')
            raise
        try:
            vm = self.hypervisor.domains[name]
        except KeyError:
            logger.exception('Cannot find domain %s on hypervisor for live'
                             ' migration', name)
            raise
        try:
            dest_virt_con = libvirt.open(
                'qemu+tcp://127.0.0.1:%d/system' % remote_virt_port)
        except libvirt.libvirtError:
            logger.exception('Cannot connect to remote libvirt for live'
                             ' migrating vm %s', name)
            raise
        try:
            if unsafe:
                # VIR_MIGRATE_UNSAFE is not defined for libvirt < 0.9.11
                append_flags = getattr(libvirt, 'VIR_MIGRATE_UNSAFE', 0)
            else:
                append_flags = 0
            vm.lv_dom.migrate(
                dest_virt_con,
                libvirt.VIR_MIGRATE_LIVE | libvirt.VIR_MIGRATE_PEER2PEER |
                libvirt.VIR_MIGRATE_TUNNELLED |
                libvirt.VIR_MIGRATE_PERSIST_DEST |
                libvirt.VIR_MIGRATE_UNDEFINE_SOURCE |
                append_flags,
                None,
                'qemu+tcp://127.0.0.1:%d/system' % remote_hv_port,
                0,
            )
        except libvirt.libvirtError:
            # FIXME maybe we should catch some weird crap libvirt bad exception
            logger.exception('Libvirt error while live migrating vm %s', name)
            raise
        finally:
            dest_virt_con.close()

        logger.debug('Sucessfuly live migrated vm %s', name)

    def vol_create(self, pool, name, size):
        logger.debug('Volume create %s, pool %s, size %s', name, pool, size)
        try:
            self.hypervisor.storage.create_volume(pool, name, size)
        except Exception:
            logger.exception('Error while creating volume')
            raise

    def vol_delete(self, pool, name):
        logger.debug('Volume delete %s, pool %s', name, pool)
        try:
            self.hypervisor.storage.delete_volume(pool, name)
        except Exception:
            logger.exception('Error while deleting volume')
            raise

    def vol_import(self, pool, name):
        """
        :param pool: pool name where the volume is
        :param name: name of the volume
        """
        logger.debug('Volume import pool = %s, volume = %s', pool, name)
        try:
            pool = self.hypervisor.storage.get_storage(pool)
            if pool is None:
                raise Exception('Pool storage does not exist')  # TODO exc

            volume = pool.volumes.get(name)
            if volume is None:
                raise Exception('Volume does not exist')

            # create the job
            job = self.main.job_manager.create(ImportVolume, volume)
            job.start()
        except Exception:
            logger.exception('Error while starting import job')
            raise

        return dict(id=job.id, port=job.port)

    def vol_import_wait(self, job_id):
        """Block until completion of the given job id."""
        job = self.main.job_manager.get(job_id)
        logger.debug('Waiting for import job to terminate')
        job.wait()
        logger.debug('Import job terminated')

        return dict(id=job.id, log='', checksum=job.checksum)

    def vol_import_cancel(self, job_id):
        """Cancel import job."""
        logger.debug('Cancel import job')
        job = self.main.job_manager.get(job_id)
        self.main.job_manager.cancel(job_id)
        # wait for job to end
        job.join()  # we don't call wait as it is already called in
                    # vol_import_wait handler

    def vol_export(self, pool, name, raddr, rport):
        """
        :param pool: pool name where the volume is
        :param name: name of the volume
        :param raddr: IP address of the destination to send the volume to
        :param rport: TCP port of the destination
        """
        pool = self.hypervisor.storage.get_storage(pool)

        if pool is None:
            raise Exception('Pool storage does not exist')

        volume = pool.volumes.get(name)

        if volume is None:
            raise Exception('Volume does not exist')

        try:
            job = self.main.job_manager.create(ExportVolume, volume, raddr, rport)
            # we don't run the job in a background thread thus exceptions are
            # sent to the sjRPC
            job.start_current()
            # otherwise we would do
            # job.start()
            # job.join()
        except Exception:
            logger.exception('Error while exporting volume')
            raise

        logger.debug('Export volume successfull')
        return dict(id=job.id, log='', checksum=job.checksum)

    @threadless
    def tun_setup(self, local=True):
        """Set up local tunnel and listen on a random port.

        :param local: indicate if we should listen on localhost or all
            interfaces
        """
        logger.debug('Tunnel setup: local = %s', local)
        # create job
        job = self.main.job_manager.create(TCPTunnel, self.main.evloop)
        job.setup_listen('127.0.0.1' if local else '0.0.0.0')
        return dict(
            jid=job.id,
            key='FIXME',
            port=job.port,
        )

    @threadless
    def tun_connect(self, res, remote_res, remote_ip):
        """Connect tunnel to the other end.

        :param res: previous result of `tun_setup` handler
        :param remote_res: other end result of `tun_setup` handler
        :param remote_ip: where to connect
        """
        logger.debug('Tunnel connect %s %s', res['jid'], remote_ip)
        job = self.main.job_manager.get(res['jid'])
        job.setup_connect((remote_ip, remote_res['port']))

    @threadless
    def tun_connect_hv(self, res, migration=False):
        """Connect tunnel to local libvirt Unix socket.

        :param res: previous result of `tun_setup` handler
        """
        logger.debug('Tunnel connect hypervisor %s', res['jid'])
        job = self.main.job_manager.get(res['jid'])
        job.setup_connect('/var/run/libvirt/libvirt-sock')

    @threadless
    def tun_destroy(self, res):
        """Close given tunnel.

        :param res: previous result as givent by `tun_setup` handler
        """
        logger.debug('Tunnel destroy %s', res['jid'])
        self.main.job_manager.cancel(res['jid'])
        self.main.job_manager.remove(res['jid'])

    def drbd_setup(self, pool, name):
        """Create DRBD volumes.

        :param pool: storage pool
        :param name: storage volume name
        """
        pool = self.hypervisor.storage.get_storage(pool)
        if pool is None:
            raise DRBDError('Cannot setup DRBD: pool storage does not exist')
        elif pool.type != 'logical':
            raise DRBDError('Cannot setup DRBD: pool storage is not LVM')

        volume = pool.volumes.get(name)
        if volume is None:
            raise DRBDError('Cannot setup DRBD: volume does not exist')

        try:
            job = self.main.job_manager.create(DRBD, self.hypervisor.storage,
                                               pool, volume)
        except Exception:
            logger.exception('Error while creating DRBD job')
            raise

        job.setup()

        logger.debug('DRBD setup successfull')
        return dict(
            jid=job.id,
            port=job.drbd_port,
        )

    def drbd_connect(self, res, remote_res, remote_ip):
        """Set up DRBD in connect mode. (Wait for connection and try to connect
        to the remote peer.

        :param res: previous result of `drbd_setup` handler
        :param remote_res: result of remote `drbd_setup` handler
        :param remote_ip: IP of remote peer
        """
        job = self.main.job_manager.get(res['jid'])
        job.connect(remote_ip, remote_res['port'])
        job.wait_connection()

    def drbd_role(self, res, primary):
        """Set up DRBD role.

        :param res: previous result of `drbd_setup` handler
        :param bool primary: if True, set up in primary mode else secondary
        """
        job = self.main.job_manager.get(res['jid'])
        if primary:
            job.switch_primary()
        else:
            job.switch_secondary()

    def drbd_takeover(self, res, state):
        """Set up DRBD device as the VM disk. FIXME

        :param res: previous result of `drbd_setup` handler
        :param state: FIXME
        """
        job = self.main.job_manager.get(res['jid'])
        job.takeover()

    def drbd_sync_status(self, res):
        """Return synchronization status of a current DRBD job.

        :param res: previous result of `drbd_setup` handler
        """
        status = self.main.job_manager.get(res['jid']).status()
        result = dict(
            done=status['disk'] == 'UpToDate',
            completion=status['percent'],
        )
        logger.debug('DRBD status %s', result)
        return result

    def drbd_shutdown(self, res):
        """Destroy DRBD related block devices.

        :param res: previous result of `drbd_setup` handler
        """
        logger.debug('DRBD shutdown')
        job = self.main.job_manager.get(res['jid'])
        job.cleanup()


class Hypervisor(object):
    """Container for all hypervisor related state."""
    def __init__(self, name, handler):
        """
        :param str name: name of hypervisor instance
        :param Handler handler: hypervisor handler
        """
        self.handler = weakref.proxy(handler)

        #: hv attributes
        self.name = name
        self.type = u'kvm'

        # register libvirt error handler
        libvirt.registerErrorHandler(self.vir_error_cb, None)
        # libvirt event loop abstraction
        self.vir_event_loop = VirEventLoop(self.handler.main.evloop)
        # This tells libvirt what event loop implementation it
        # should use
        libvirt.virEventRegisterImpl(
            self.vir_event_loop.add_handle,
            self.vir_event_loop.update_handle,
            self.vir_event_loop.remove_handle,
            self.vir_event_loop.add_timer,
            self.vir_event_loop.update_timer,
            self.vir_event_loop.remove_timer,
        )

        self.vir_con = libvirt.open('qemu:///system')  # currently only support KVM

        # findout storage
        self.storage = StorageIndex(handler, self.vir_con)

        logger.debug('Storages: %s', self.storage.paths)

        #: domains: vms, containers...
        self.domains = dict()
        # find defined domains
        for dom_name in self.vir_con.listDefinedDomains():
            dom = self.vir_con.lookupByName(dom_name)
            self.domains[dom.name()] = VirtualMachine(dom, self)
        # find started domains
        for dom_id in self.vir_con.listDomainsID():
            dom = self.vir_con.lookupByID(dom_id)
            self.domains[dom.name()] = VirtualMachine(dom, self)

        logger.debug('Domains: %s', self.domains)

        self.vir_con.domainEventRegister(self.vir_cb, None)  # TODO find out args

    def stop(self):
        self.vir_event_loop.stop()
        # unregister callback
        try:
            self.vir_con.domainEventDeregister(self.vir_cb)
        except libvirt.libvirtError:
            # in case the libvirt connection is broken, it will raise the error
            pass
        ret = self.vir_con.close()
        logger.debug('Libvirt still handling %s ref connections', ret)
        # TODO delet objects

    def vir_error_cb(self, ctxt, err):
        """Libvirt error callback.

        See http://libvirt.org/errors.html for more informations.

        :param ctxt: arbitrary context data (not needed because context is
            givent by self
        :param err: libvirt error code
        """
        logger.error('Libvirt error %s', err)

    def vir_cb(self, conn, dom, event, detail, opaque):
        """Callback for libvirt event loop."""
        logger.debug('Received event %s on domain %s, detail %s', event,
                     dom.name(), detail)

        event = EVENTS[event]

        if event == 'Added':
            # update Storage pools in case VM has volumes that were created
            self.storage.update()
            if dom.name() in self.domains:
                # sometimes libvirt send us the same event multiple times
                # this can be the result of a change in the domain configuration
                # we first remove the old domain
                vm = self.domains.pop(dom.name())
                self.handler.tag_db.remove_sub_object(vm.name)
                logger.debug('Domain %s recreated', dom.name())
            vm = VirtualMachine(dom, self)
            logger.info('Created domain %s', vm.name)
            self.domains[vm.name] = vm
            self.handler.tag_db.add_sub_object(vm.name, vm.tags.itervalues())
        elif event == 'Removed':
            vm = self.domains.pop(dom.name())
            logger.info('Removed domain %s', vm.name)
            self.handler.tag_db.remove_sub_object(vm.name)
            # update Storage pools in case VM had volumes that were deleted
            self.storage.update()
        elif event in ('Started', 'Suspended', 'Resumed', 'Stopped', 'Saved',
                       'Restored'):
            vm = self.domains.get(dom.name())
            # sometimes libvirt sent a start event before a created event so be
            # careful
            if vm is not None:
                state = DOMAIN_STATES[dom.info()[0]]
                logger.info('Domain change state from %s to %s', vm.state,
                             state)
                vm.state = state

        # update domain state counts
        for tag in ('nvm', 'vmpaused', 'vmstarted', 'vmstopped'):
            self.handler.tag_db['__main__'][tag].update_value()

    def vm_define(self, xml_desc):
        """Create a VM on the Hypervisor
        :param str xml_desc: XML description in libvirt format
        :return: VM name created
        """
        try:
            return self.vir_con.defineXML(xml_desc).name()
        except libvirt.libvirtError:
            logger.exception('Error while creating domain')
            # reraise exception for the cc-server
            raise

    def _count_domain(self, filter=lambda d: True):
        count = 0

        for dom in self.domains.itervalues():
            if filter(dom):
                count += 1

        return count

    @property
    def vm_started(self):
        """Number of VMs started."""
        return self._count_domain(lambda d: d.state == 'running')

    @property
    def vm_stopped(self):
        """Number of VMs stopped."""
        return self._count_domain(lambda d: d.state == 'stopped')

    @property
    def vm_paused(self):
        """Number of VMs paused."""
        return self._count_domain(lambda d: d.state == 'paused')

    @property
    def vm_total(self):
        """Total number of VMs on the hypervisor."""
        return self._count_domain()


class StorageIndex(object):
    """Keep an index of all storage volume paths."""
    def __init__(self, handler, lv_con):
        """
        :param handler: Hypervisor handler instance
        :param lv_con: Libvirt connection
        """
        self.handler = handler
        self.lv_con = lv_con
        self.storages = dict(
            (s.name, s) for s in imap(
                Storage,
                imap(
                    lv_con.storagePoolLookupByName,
                    chain(
                        lv_con.listDefinedStoragePools(),
                        lv_con.listStoragePools(),
                    ),
                ),
            ),
        )

        self.paths = None
        self.update_path_index()


    def update(self):
        """Update storage pools and volumes."""
        # go through all storage pools and check if it is already in the index
        for lv_storage in imap(
            self.lv_con.storagePoolLookupByName,
            chain(
                self.lv_con.listDefinedStoragePools(),
                self.lv_con.listStoragePools(),
            ),
        ):
            if lv_storage.name() in self.storages:
                # update
                self.storages[lv_storage.name()].update()
            else:
                # add storage pool
                s = Storage(lv_storage)
                self.storages[s.name] = s
                # add tags
                self.handler.tag_db.add_tags((
                    Tag('sto%s_state' % s.name, lambda: s.state, 5, 5),
                    Tag('sto%s_size' % s.name, lambda: s.capacity, 5, 5),
                    Tag('sto%s_free' % s.name, lambda: s.available, 5, 5),
                    Tag('sto%s_used' % s.name,
                        lambda: s.capacity - s.available, 5, 5),
                    Tag('sto%s_type' % s.name, lambda: s.type, 5, 5),
                ))

        self.update_path_index()

    def update_path_index(self):
        self.paths = dict(
            (v.path, v) for v in chain.from_iterable(imap(
                lambda s: s.volumes.itervalues(),
                self.storages.itervalues(),
            )),
        )

    def get_volume(self, path):
        return self.paths.get(path)

    def get_storage(self, name):
        return self.storages.get(name)

    def create_volume(self, pool_name, volume_name, capacity):
        """Create a new volume in the storage pool.

        :param str name: name for the volume
        :param int capacity: size for the volume
        """
        # get volume
        logger.debug('asked pool %s', pool_name)
        logger.debug('Pool state %s', self.storages)
        try:
            pool = self.storages[pool_name]
        except KeyError:
            raise PoolStorageError('Invalid pool name')
        if pool is None:
            raise Exception('Storage pool not found')
        try:
            new_volume = pool.lv_storage.createXML("""<volume>
                                        <name>%s</name>
                                        <capacity>%d</capacity>
                                      </volume>""" % (volume_name, capacity), 0)
        except libvirt.libvirtError:
            logger.exception('Error while creating volume')
            raise

        new_volume = Volume(new_volume)
        # if success add the volume to the index
        self.paths[new_volume.path] = new_volume
        # and also to its storage pool
        self.storages[new_volume.storage].volumes[new_volume.name] = new_volume

        return new_volume

    def delete_volume(self, pool_name, volume_name):
        """Delete a volume in the givent storage pool.

        :param str pool_name: name for the storage pool
        :param str volume_name: name for the volume
        """
        # get volume
        try:
            pool = self.storages[pool_name]
        except KeyError:
            raise PoolStorageError('Invalid pool name')
        try:
            volume = pool.volumes[volume_name]
        except KeyError:
            raise PoolStorageError('Invalid volume name')
        # delete from index
        del self.paths[volume.path]
        del self.storages[pool_name].volumes[volume_name]

        # delete volume
        try:
            volume.lv_volume.delete(0)
        except libvirt.libvirtError:
            logger.exception('Error while deleting volume')
            raise


class Storage(object):
    """Storage abstraction."""
    def __init__(self, lv_storage):
        """
        :param lv_storage: Libvirt pool storage instance
        """
        self.uuid = lv_storage.UUID()
        self.name = lv_storage.name()
        self.lv_storage = lv_storage

        self.state, self.capacity = None, None
        self.allocation, self.available = None, None

        self.type = et.ElementTree().parse(
            StringIO(lv_storage.XMLDesc(0))).get('type')

        self.volumes = dict((v.name, v) for v in imap(
            Volume,
            (lv_storage.storageVolLookupByName(n) for n in
             lv_storage.listVolumes()),
        ))

        self.update_attr()

    def update(self):
        self.update_attr()

        # update volumes
        for vol_name in self.lv_storage.listVolumes():
            if vol_name in self.volumes:
                # update volume
                self.volumes[vol_name].update()
            else:
                # add volume
                v = Volume(self.lv_storage.storageVolLookupByName(vol_name))
                self.volumes[v.name] = v

    def update_attr(self):
        self.state, self.capacity, self.allocation, self.available = self.lv_storage.info()
        self.state = STORAGE_STATES[self.state]

        self.type = et.ElementTree().parse(
            StringIO(self.lv_storage.XMLDesc(0))).get('type')



class Volume(object):
    """Volume abstraction."""
    def __init__(self, lv_volume):
        """
        :param lv_volume: Libvirt volume instance
        """
        self.storage = lv_volume.storagePoolLookupByVolume().name()
        self.path = lv_volume.path()
        self.name = lv_volume.name()
        self.capacity, self.allocation = None, None
        self.lv_volume = lv_volume
        self.update()

    def update(self):
        self.capacity, self.allocation = self.lv_volume.info()[1:]