Instantiate inspector in compute manager

As suggested in the review of the original inspector patch
(I20700320dd7e3196507173c780ab598b479e4021), the inspector
lifecycle is now controlled by the compute manager as
opposed to the pollsters.

Change-Id: Ifdef5ab22e7fb224e273dae5dbff3fb4dab10031

ceilometer/compute/pollsters.py

@@ -21,26 +21,12 @@
 import copy
 import datetime
 
-from stevedore import driver
-
 from ceilometer import counter
 from ceilometer.compute import plugin
 from ceilometer.compute import instance as compute_instance
-from ceilometer.compute.virt import inspector as virt_inspector
-from ceilometer.openstack.common import cfg
-from ceilometer.openstack.common import importutils
 from ceilometer.openstack.common import log
 from ceilometer.openstack.common import timeutils
 
-OPTS = [
-    cfg.StrOpt('hypervisor_inspector',
-               help='Inspector to use for inspecting the hypervisor layer',
-               default='libvirt')
-]
-
-CONF = cfg.CONF
-CONF.register_opts(OPTS)
-
 LOG = log.getLogger(__name__)
 
 
@@ -49,18 +35,6 @@ def _instance_name(instance):
     return getattr(instance, 'OS-EXT-SRV-ATTR:instance_name', None)
 
 
-def get_hypervisor_inspector():
-    try:
-        namespace = 'ceilometer.compute.virt'
-        mgr = driver.DriverManager(namespace,
-                                   CONF.hypervisor_inspector,
-                                   invoke_on_load=True)
-        return mgr.driver
-    except ImportError as e:
-        LOG.error("Unable to load the hypervisor inspector: %s" % (e))
-        return virt_inspector.Inspector()
-
-
 def make_counter_from_instance(instance, name, type, volume):
     return counter.Counter(
         name=name,
@@ -74,16 +48,7 @@ def make_counter_from_instance(instance, name, type, volume):
         )
 
 
-class HypervisorPollster(plugin.ComputePollster):
-
-    inspector = None
-
-    def __init__(self):
-        if not HypervisorPollster.inspector:
-            HypervisorPollster.inspector = get_hypervisor_inspector()
-
-
-class InstancePollster(HypervisorPollster):
+class InstancePollster(plugin.ComputePollster):
 
     def get_counters(self, manager, instance):
         yield make_counter_from_instance(instance,
@@ -99,7 +64,7 @@ class InstancePollster(HypervisorPollster):
         )
 
 
-class DiskIOPollster(HypervisorPollster):
+class DiskIOPollster(plugin.ComputePollster):
 
     LOG = log.getLogger(__name__ + '.diskio')
 
@@ -119,7 +84,7 @@ class DiskIOPollster(HypervisorPollster):
             r_requests = 0
             w_bytes = 0
             w_requests = 0
-            for disk, info in self.inspector.inspect_disks(instance_name):
+            for disk, info in manager.inspector.inspect_disks(instance_name):
                 self.LOG.info(self.DISKIO_USAGE_MESSAGE,
                               instance, disk.device, info.read_requests,
                               info.read_bytes, info.write_requests,
@@ -154,7 +119,7 @@ class DiskIOPollster(HypervisorPollster):
             self.LOG.exception(err)
 
 
-class CPUPollster(HypervisorPollster):
+class CPUPollster(plugin.ComputePollster):
 
     LOG = log.getLogger(__name__ + '.cpu')
 
@@ -181,7 +146,7 @@ class CPUPollster(HypervisorPollster):
         self.LOG.info('checking instance %s', instance.id)
         instance_name = _instance_name(instance)
         try:
-            cpu_info = self.inspector.inspect_cpus(instance_name)
+            cpu_info = manager.inspector.inspect_cpus(instance_name)
             self.LOG.info("CPUTIME USAGE: %s %d",
                           instance.__dict__, cpu_info.time)
             cpu_util = self.get_cpu_util(instance, cpu_info)
@@ -208,7 +173,7 @@ class CPUPollster(HypervisorPollster):
             self.LOG.exception(err)
 
 
-class NetPollster(HypervisorPollster):
+class NetPollster(plugin.ComputePollster):
 
     LOG = log.getLogger(__name__ + '.net')
 
@@ -236,7 +201,7 @@ class NetPollster(HypervisorPollster):
         instance_name = _instance_name(instance)
         self.LOG.info('checking instance %s', instance.id)
         try:
-            for vnic, info in self.inspector.inspect_vnics(instance_name):
+            for vnic, info in manager.inspector.inspect_vnics(instance_name):
                 self.LOG.info(self.NET_USAGE_MESSAGE, instance_name,
                               vnic.name, info.rx_bytes, info.tx_bytes)
                 yield self.make_vnic_counter(instance,