Make collectd available to plugin components

Collectd module could be required by plugin components
but importing it from their modules makes unit testing
harder because it would require running tests from
inside collectd process.

This changes make the module available by passing it
to component constructors which makes testing and mocking
easier.

Related-Bug: #1583301
Change-Id: I6abfd330c8f3b5108e78543df7c803cd65a15655

collectd_ceilometer/meters/base.py

@@ -21,6 +21,9 @@ from collectd_ceilometer.settings import Config
 class Meter(object):
     """Default collectd meter"""
 
+    def __init__(self, collectd):
+        self._collectd = collectd
+
     def meter_name(self, vl):
         """Return meter name"""
         # pylint: disable=no-self-use

collectd_ceilometer/meters/libvirt.py

@@ -24,7 +24,8 @@ import threading
 class LibvirtMeter(Meter):
     """Specialization for libvirt plugin"""
 
-    def __init__(self):
+    def __init__(self, collectd):
+        super(LibvirtMeter, self).__init__(collectd=collectd)
         self._cache_lock = threading.Lock()
         self._conn = None
         self._vms = {}

collectd_ceilometer/meters/storage.py

@@ -29,12 +29,12 @@ class MeterStorage(object):
         'libvirt': LibvirtMeter,
     }
 
-    def __init__(self):
+    def __init__(self, collectd):
         self._meters = {}
-        self._default = Meter()
+        self._default = Meter(collectd=collectd)
 
         # fill dict with specialized meters classes
-        self._meters = {key: meter_class()
+        self._meters = {key: meter_class(collectd=collectd)
                         for key, meter_class in six.iteritems(self._classes)}
 
     def get(self, plugin):

collectd_ceilometer/plugin.py

@@ -51,7 +51,7 @@ class Plugin(object):
         """Initialization callback"""
 
         collectd.info('Initializing the collectd OpenStack python plugin')
-        self._meters = MeterStorage()
+        self._meters = MeterStorage(collectd=collectd)
         self._writer = Writer(self._meters)
 
     def write(self, vl, data=None):