# Copyright (c) 2012 OpenStack Foundation
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""
Track resources like memory and disk for a compute host.  Provides the
scheduler with useful information about availability through the ComputeNode
model.
"""
import collections
import copy

from oslo_log import log as logging
from oslo_serialization import jsonutils

from nova.compute import claims
from nova.compute import monitors
from nova.compute import stats
from nova.compute import task_states
from nova.compute import vm_states
import nova.conf
from nova import exception
from nova.i18n import _, _LI, _LW
from nova import objects
from nova.objects import base as obj_base
from nova.objects import migration as migration_obj
from nova.pci import manager as pci_manager
from nova.pci import request as pci_request
from nova import rpc
from nova.scheduler import client as scheduler_client
from nova import utils
from nova.virt import hardware

CONF = nova.conf.CONF

LOG = logging.getLogger(__name__)
COMPUTE_RESOURCE_SEMAPHORE = "compute_resources"


def _instance_in_resize_state(instance):
    """Returns True if the instance is in one of the resizing states.

    :param instance: `nova.objects.Instance` object
    """
    vm = instance.vm_state
    task = instance.task_state

    if vm == vm_states.RESIZED:
        return True

    if (vm in [vm_states.ACTIVE, vm_states.STOPPED]
            and task in [task_states.RESIZE_PREP,
            task_states.RESIZE_MIGRATING, task_states.RESIZE_MIGRATED,
            task_states.RESIZE_FINISH, task_states.REBUILDING]):
        return True

    return False


def _is_trackable_migration(migration):
    # Only look at resize/migrate migration and evacuation records
    # NOTE(danms): RT should probably examine live migration
    # records as well and do something smart. However, ignore
    # those for now to avoid them being included in below calculations.
    return migration.migration_type in ('resize', 'migration',
                                        'evacuation')


class ResourceTracker(object):
    """Compute helper class for keeping track of resource usage as instances
    are built and destroyed.
    """

    def __init__(self, host, driver):
        self.host = host
        self.driver = driver
        self.pci_tracker = None
        # Dict of objects.ComputeNode objects, keyed by nodename
        self.compute_nodes = {}
        self.stats = stats.Stats()
        self.tracked_instances = {}
        self.tracked_migrations =
 {}
        monitor_handler = monitors.MonitorHandler(self)

        self.monitors = monitor_handler.monitors
        self.old_resources = collections.defaultdict(objects.ComputeNode)
        self.scheduler_client = scheduler_client.SchedulerClient()
        self.reportclient = self.scheduler_client.reportclient
        self.ram_allocation_ratio = CONF.ram_allocation_ratio
        self.cpu_allocation_ratio = CONF.cpu_allocation_ratio
        self.disk_allocation_ratio = CONF.disk_allocation_ratio

    @utils.synchronized(COMPUTE_RESOURCE_SEMAPHORE)
    def instance_claim(self, context, instance, nodename, limits=None):
        """Indicate that some resources are needed for an upcoming compute
        instance build operation.

        This should be called before the compute node is about to perform
        an instance build operation that will consume additional resources.

        :param context: security context
        :param instance: instance to reserve resources for.
        :type instance: nova.objects.instance.Instance object
        :param nodename: The Ironic nodename selected by the scheduler
        :param limits: Dict of oversubscription limits for memory, disk,
                       and CPUs.
        :returns: A Claim ticket representing the reserved resources.  It can
                  be used to revert the resource usage if an error occurs
                  during the instance build.
        """
        if self.disabled(nodename):
            # instance_claim() was called before update_available_resource()
            # (which ensures that a compute node exists for nodename). We
            # shouldn't get here but in case we do, just set the instance's
            # host and nodename attribute (probably incorrect) and return a
            # NoopClaim.
            # TODO(jaypipes): Remove all the disabled junk from the resource
            # tracker. Servicegroup API-level active-checking belongs in the
            # nova-compute manager.
            self._set_instance_host_and_node(instance, nodename)
            return claims.NopClaim()

        # sanity checks:
        if instance.host:
            LOG.warning(_LW("Host field should not be set on the instance "
                            "until resources have been claimed."),
                        instance=instance)

        if instance.node:
            LOG.warning(_LW("Node field should not be set on the instance "
                            "until resources have been claimed."),
                        instance=instance)

        # get the overhead required to build this instance:
        overhead = self.driver.estimate_instance_overhead(instance)
        LOG.debug("Memory overhead for %(flavor)d MB instance; %(overhead)d "
                  "MB", {'flavor': instance.flavor.memory_mb,
                          'overhead': overhead['memory_mb']})
        LOG.debug("Disk overhead for %(flavor)d GB instance; %(overhead)d "
                  "GB", {'flavor': instance.flavor.root_gb,
                         'overhead': overhead.get('disk_gb', 0)})
        LOG.debug("CPU overhead for %(flavor)d vCPUs instance; %(overhead)d "
                  "vCPU(s)", {'flavor': instance.flavor.vcpus,
                              'overhead': overhead.get('vcpus', 0)})

        cn = self.compute_nodes[nodename]
        pci_requests = objects.InstancePCIRequests.get_by_instance_uuid(
            context, instance.uuid)
        claim = claims.Claim(context, instance, nodename, self, cn,
                             pci_requests, overhead=overhead, limits=limits)

        # self._set_instance_host_and_node() will save instance to the DB
        # so set instance.numa_topology first.  We need to make sure
        # that numa_topology is saved while under COMPUTE_RESOURCE_SEMAPHORE
        # so that the resource audit knows about any cpus we've pinned.
        instance_numa_topology = claim.claimed_numa_topology
        instance.numa_topology = instance_numa_topology
        self._set_instance_host_and_node(instance, nodename)

        if self.pci_tracker:
            # NOTE(jaypipes): ComputeNode.pci_device_pools is set below
            # in _update_usage_from_instance().
            self.pci_tracker.claim_instance(context, pci_requests,
                                            instance_numa_topology)

        # Mark resources in-use and update stats
        self._update_usage_from_instance(context, instance, nodename)

        elevated = context.elevated()
        # persist changes to the compute node:
        self._update(elevated, cn)

        return claim

    @utils.synchronized(COMPUTE_RESOURCE_SEMAPHORE)
    def rebuild_claim(self, context, instance, nodename, limits=None,
                      image_meta=None, migration=None):
        """Create a claim for a rebuild operation."""
        instance_type = instance.flavor
        return self._move_claim(context, instance, instance_type, nodename,
                                move_type='evacuation', limits=limits,
                                image_meta=image_meta, migration=migration)

    @utils.synchronize