implement cache data for zvm inspector

CacheData class is used in zvm inspector to cache instance data
when getting instance performance info.

Change-Id: Icc3422d8322d7246840841fbde7bb3abb6ce7213

ceilometer_zvm/compute/virt/zvm/utils.py

@@ -33,6 +33,25 @@ class ZVMException(inspector.InspectorException):
     pass
 
 
+class CacheData(object):
+
+    def __init__(self):
+        self.cache = {}
+
+    def set(self, inst_stat):
+        self.cache[inst_stat['nodename']] = inst_stat
+
+    def get(self, inst_name):
+        return self.cache.get(inst_name, None)
+
+    def delete(self, inst_name):
+        if inst_name in self.cache:
+            del self.cache[inst_name]
+
+    def clear(self):
+        self.cache = {}
+
+
 class XCATUrl(object):
     """To return xCAT url for invoking xCAT REST API."""
     def __init__(self):

ceilometer_zvm/tests/unit/compute/virt/zvm/test_utils.py

@@ -116,3 +116,33 @@ class TestZVMUtils(base.BaseTestCase):
         xcat_req.assert_any_call('PUT',
             '/xcatws/nodes/node/dsh?userName=user&password=pwd&format=json',
             ['command=cmds'])
+
+
+class TestCacheData(base.BaseTestCase):
+
+    def setUp(self):
+        super(TestCacheData, self).setUp()
+        self.cache_data = zvmutils.CacheData()
+
+    def tearDown(self):
+        self.cache_data.clear()
+        super(TestCacheData, self).tearDown()
+
+    def test_set(self):
+        self.cache_data.set({'nodename': 'node'})
+        self.assertEqual({'nodename': 'node'}, self.cache_data.cache['node'])
+
+    def test_get(self):
+        self.cache_data.set({'nodename': 'node'})
+        self.assertEqual({'nodename': 'node'}, self.cache_data.get('node'))
+
+    def test_delete(self):
+        self.cache_data.set({'nodename': 'node'})
+        self.cache_data.delete('node')
+        self.assertEqual(None, self.cache_data.get('node'))
+
+    def test_clear(self):
+        self.cache_data.set({'nodename': 'node1'})
+        self.cache_data.set({'nodename': 'node2'})
+        self.cache_data.clear()
+        self.assertEqual({}, self.cache_data.cache)