Merge pull request #634 from datastax/561-2

PYTHON-561: Changed per-cluster metrics path and added ability to define an explicit stats name

cassandra/metrics.py

@@ -111,12 +111,14 @@ class Metrics(object):
     the driver currently has open.
     """
 
+    _stats_counter = 0
+
     def __init__(self, cluster_proxy):
         log.debug("Starting metric capture")
 
-        # TODO, modify the path to /cassandra/{clusterid} in 4.0
+        self.stats_name = 'cassandra-{0}'.format(str(self._stats_counter))
-        self.stats_id = str(id(cluster_proxy))
+        Metrics._stats_counter += 1
-        self.stats = scales.collection('/_cassandra/{0}'.format(self.stats_id),
+        self.stats = scales.collection(self.stats_name,
             scales.PmfStat('request_timer'),
             scales.IntStat('connection_errors'),
             scales.IntStat('write_timeouts'),
@@ -137,7 +139,7 @@ class Metrics(object):
         # TODO, to be removed in 4.0
         # /cassandra contains the metrics of the first cluster registered
         if 'cassandra' not in scales._Stats.stats:
-            scales._Stats.stats['cassandra'] = scales._Stats.stats['_cassandra'][self.stats_id]
+            scales._Stats.stats['cassandra'] = scales._Stats.stats[self.stats_name]
 
         self.request_timer = self.stats.request_timer
         self.connection_errors = self.stats.connection_errors
@@ -176,4 +178,19 @@ class Metrics(object):
         """
         Returns the metrics for the registered cluster instance.
         """
-        return scales.getStats()['_cassandra'][self.stats_id]
+        return scales.getStats()[self.stats_name]
+
+    def set_stats_name(self, stats_name):
+        """
+        Set the metrics stats name.
+        The stats_name is a string used to access the metris through scales: scales.getStats()[<stats_name>]
+        Default is 'cassandra-<num>'.
+        """
+
+        if stats_name in scales._Stats.stats:
+            raise ValueError('"{0}" already exists in stats.'.format(stats_name))
+
+        stats = scales._Stats.stats[self.stats_name]
+        del scales._Stats.stats[self.stats_name]
+        self.stats_name = stats_name
+        scales._Stats.stats[self.stats_name] = stats

tests/integration/standard/test_metrics.py

@@ -26,7 +26,7 @@ from cassandra import ConsistencyLevel, WriteTimeout, Unavailable, ReadTimeout
 
 from cassandra.cluster import Cluster, NoHostAvailable
 from tests.integration import get_cluster, get_node, use_singledc, PROTOCOL_VERSION, execute_until_pass
-
+from greplin import scales
 
 def setup_module():
     use_singledc()
@@ -197,14 +197,23 @@ class MetricsTests(unittest.TestCase):
         finally:
             get_node(1).resume()
 
+        # Change the scales stats_name of the cluster2
+        cluster2.metrics.set_stats_name('cluster2-metrics')
+
         stats_cluster1 = self.cluster.metrics.get_stats()
         stats_cluster2 = cluster2.metrics.get_stats()
 
+        # Test direct access to stats
         self.assertEqual(1, self.cluster.metrics.stats.write_timeouts)
         self.assertEqual(0, cluster2.metrics.stats.write_timeouts)
 
+        # Test direct access to a child stats
         self.assertNotEqual(0.0, self.cluster.metrics.request_timer['mean'])
         self.assertEqual(0.0, cluster2.metrics.request_timer['mean'])
 
+        # Test access via metrics.get_stats()
         self.assertNotEqual(0.0, stats_cluster1['request_timer']['mean'])
         self.assertEqual(0.0, stats_cluster2['request_timer']['mean'])
+
+        # Test access by stats_name
+        self.assertEqual(0.0, scales.getStats()['cluster2-metrics']['request_timer']['mean'])