Merge pull request #112 from Helene/singleton

make MetadataHandler class Singleton

Author: Helene

source/metaclasses.py

@@ -0,0 +1,31 @@
+'''
+##############################################################################
+# Copyright 2023 IBM Corp.
+#
+# 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.
+##############################################################################
+
+Created on Sep 22, 2023
+
+@author: HWASSMAN
+'''
+
+
+class Singleton(type):
+    """metaclass to make a class a singleton"""
+    _instances = {}
+
+    def __call__(cls, *args, **kwargs):
+        if cls not in cls._instances:
+            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
+        return cls._instances[cls]

source/zimonGrafanaIntf.py

@@ -34,27 +34,28 @@
 from queryHandler import SensorConfig
 from __version__ import __version__
 from messages import ERR, MSG
+from metaclasses import Singleton
 from bridgeLogger import configureLogging
 from confParser import getSettings
 from collections import defaultdict
 from timeit import default_timer as timer
 from time import sleep
 
 
-class MetadataHandler():
+class MetadataHandler(metaclass=Singleton):
 
-    def __init__(self, logger, server, port, apiKeyName, apiKeyValue, caCertPath=False, includeDiskData=False, sleepTime=None):
+    def __init__(self, **kwargs):
         self.__qh = None
         self.__sensorsConf = None
         self.__metaData = None
-        self.logger = logger
-        self.server = server
-        self.port = port
-        self.apiKeyName = apiKeyName
-        self.apiKeyValue = apiKeyValue
-        self.caCertPath = caCertPath
-        self.includeDiskData = includeDiskData
-        self.sleepTime = sleepTime or 60
+        self.logger = kwargs['logger']
+        self.server = kwargs['server']
+        self.port = kwargs['port']
+        self.apiKeyName = kwargs['apiKeyName']
+        self.apiKeyValue = kwargs['apiKeyValue']
+        self.caCertPath = kwargs.get('caCertPath', False)
+        self.includeDiskData = kwargs.get('includeDiskData', False)
+        self.sleepTime = kwargs.get('sleepTime', 60)
 
         self.__initializeTables()
 
@@ -625,8 +626,8 @@ def main(argv):
         logger.info("%s", MSG['BridgeVersionInfo'].format(__version__))
         logger.details('zimonGrafanaItf invoked with parameters:\n %s', "\n".join("{}={}".format(k, v) for k, v in args.items() if not k == 'apiKeyValue'))
         # logger.details('zimonGrafanaItf invoked with parameters:\n %s', "\n".join("{}={}".format(k, type(v)) for k, v in args.items()))
-        mdHandler = MetadataHandler(logger, args.get('server'), args.get('serverPort'), args.get('apiKeyName'), resolveAPIKeyValue(args.get('apiKeyValue')),
-                                    args.get('caCertPath'), args.get('includeDiskData'), args.get('retryDelay', None))
+        mdHandler = MetadataHandler(logger=logger, server=args.get('server'), port=args.get('serverPort'), apiKeyName=args.get('apiKeyName'), apiKeyValue=resolveAPIKeyValue(args.get('apiKeyValue')),
+                                    caCertPath=args.get('caCertPath'), includeDiskData=args.get('includeDiskData'), sleepTime=args.get('retryDelay', None))
     except (AttributeError, TypeError, ValueError) as e:
         logger.details('%s', MSG['IntError'].format(str(e)))
         logger.error(MSG['MetaError'])

tests/test_metadatahandler.py

@@ -0,0 +1,43 @@
+import os
+from source.bridgeLogger import configureLogging
+from source.zimonGrafanaIntf import MetadataHandler
+from nose2.tools.such import helper as assert_helper
+from nose2.tools.decorators import with_setup
+
+
+def my_setup():
+    global path, logger, mainSensorsConfig, wrongSensorsConfig, sensorsCount, myFile
+    path = os.getcwd()
+    logger = configureLogging(path, None)
+    mainSensorsConfig = 'ZIMonSensors.cfg'
+    wrongSensorsConfig = 'ZIMonSensors-protocols-wrong.cfg'
+    myFile = os.path.join(path, "tests", "test_data", mainSensorsConfig)
+    sensorsCount = 0
+
+
+@with_setup(my_setup)
+def test_case01():
+    with assert_helper.assertRaises(KeyError):
+        MetadataHandler()
+
+
+@with_setup(my_setup)
+def test_case02():
+    with assert_helper.assertRaises(KeyError):
+        MetadataHandler(logger=logger, apiKeyName='scale_grafana')
+
+
+@with_setup(my_setup)
+def test_case03():
+    with assert_helper.assertRaises(KeyError):
+        MetadataHandler(logger=logger, server='localhost', port='4242', apiKeyName='scale_grafana')
+
+
+@with_setup(my_setup)
+def test_case04():
+    with assert_helper.assertRaises(OSError):
+        md = MetadataHandler(logger=logger, server='localhost', port='4242', apiKeyName='scale_grafana', apiKeyValue='85bbe7f2-5f0f-43c8-88dd-9673c9e61390')
+        md1 = MetadataHandler()
+        assert md == md1
+        assert md1.logger == logger
+        assert md1.apiKeyName == 'scale_grafana'