Synnefo

from django.db import IntegrityError

from hashlib import sha1

from synnefo.api.faults import ServiceUnavailable

from synnefo.util.rapi import GanetiRapiClient

BACKEND_CLIENTS = {}    #{hash:Backend client}

BACKEND_HASHES = {}     #{Backend.id:hash}

def get_client(hash, backend):

    """Get a cached backend client or create a new one.

    @param hash: The hash of the backend

    @param backend: Either a backend object or backend ID

    """

    if backend is None:

        raise Exception("Backend is None. Cannot create a client.")

    if hash in BACKEND_CLIENTS:

        # Return cached client

        return BACKEND_CLIENTS[hash]

    # Always get a new instance to ensure latest credentials

    if isinstance(backend, Backend):

        backend = backend.id

    (credentials,) = Backend.objects.filter(id=backend).values_list('hash',

                                'clustername', 'port', 'username', 'password')

    hash, clustername, port, user, password = credentials

    # Check client for updated hash

    if hash in BACKEND_CLIENTS:

        return BACKEND_CLIENTS[hash]

    # Delete old version of the client

    if backend in BACKEND_HASHES:

        del BACKEND_CLIENTS[BACKEND_HASHES[backend]]

    # Create the new client

    client = GanetiRapiClient(clustername, port, user, password)

    # Store the client and the hash

    BACKEND_CLIENTS[hash] = client

    BACKEND_HASHES[backend] = hash

    return client

def clear_client_cache():

    BACKEND_CLIENTS.clear()

    BACKEND_HASHES.clear()

class BackendQuerySet(models.query.QuerySet):

    def delete(self):

        for backend in self._clone():

            backend.delete()

class ProtectDeleteManager(models.Manager):

    def get_query_set(self):

        return BackendQuerySet(self.model, using=self._db)

class Backend(models.Model):

    clustername = models.CharField('Cluster Name', max_length=128, unique=True)

    port = models.PositiveIntegerField('Port', default=5080)

    username = models.CharField('Username', max_length=64, blank=True,

                                null=True)

    password = models.CharField('Password', max_length=64, blank=True,

                                null=True)

    # Sha1 is up to 40 characters long

    hash = models.CharField('Hash', max_length=40, editable=False, null=False)

    drained = models.BooleanField('Drained', default=False, null=False)

    offline = models.BooleanField('Offline', default=False, null=False)

    # Last refresh of backend resources

    updated = models.DateTimeField(auto_now_add=True)

    # Backend resources

    mfree = models.PositiveIntegerField('Free Memory', default=0, null=False)

    mtotal = models.PositiveIntegerField('Total Memory', default=0, null=False)

    dfree = models.PositiveIntegerField('Free Disk', default=0, null=False)

    dtotal = models.PositiveIntegerField('Total Disk', default=0, null=False)

    pinst_cnt = models.PositiveIntegerField('Primary Instances', default=0,

                                            null=False)

    ctotal = models.PositiveIntegerField('Total number of logical processors',

                                         default=0, null=False)

    # Custom object manager to protect from cascade delete

    objects = ProtectDeleteManager()

    class Meta:

        verbose_name = u'Backend'

        ordering = ["clustername"]

    def __unicode__(self):

        return self.clustername

    @property

    def backend_id(self):

        return self.id

    @property

    def client(self):

        """Get or create a client. """

        if not self.offline:

            return get_client(self.hash, self)

        else:

            raise ServiceUnavailable

    def create_hash(self):

        """Create a hash for this backend. """

        return sha1('%s%s%s%s' % \

                (self.clustername, self.port, self.username, self.password)) \

                .hexdigest()

    def save(self, *args, **kwargs):

        # Create a new hash each time a Backend is saved

        old_hash = self.hash

        self.hash = self.create_hash()

        super(Backend, self).save(*args, **kwargs)

        if self.hash != old_hash:

            # Populate the new hash to the new instances

            self.virtual_machines.filter(deleted=False).update(backend_hash=self.hash)

    def delete(self, *args, **kwargs):

        # Integrity Error if non-deleted VMs are associated with Backend

        if self.virtual_machines.filter(deleted=False).count():

            raise IntegrityError("Non-deleted virtual machines are associated "

                                 "with backend: %s" % self)

        else:

            # ON_DELETE = SET NULL

            self.virtual_machines.all().backend=None

            super(Backend, self).delete(*args, **kwargs)

    backend = models.ForeignKey(Backend, null=True,

                                related_name="virtual_machines",)

    backend_hash = models.CharField(max_length=128, null=True, editable=False)

                                     null=True)

                                        max_length=30, null=True)

    @property

    def client(self):

        if not self.backend.offline:

            return get_client(self.backend_hash, self.backend_id)

        else:

            raise ServiceUnavailable

    def save(self, *args, **kwargs):

        # Store hash for first time saved vm

        if (self.id is None or self.backend_hash == '') and self.backend:

            self.backend_hash = self.backend.hash

        super(VirtualMachine, self).save(*args, **kwargs)