Fix Metric Statistics period call

Default InfluxDB behaviour is to return a timestamp with no value for
each time period requested. Since we remove those from the return value,
this behaviour breaks pagination because it thinks we hit the limit
but we returned nothing. With fill(none), Influx will not return a
timestamp for a period with no value, which fixes limit and pagination.

Change-Id: I81a7d3610541ef4b333b11e54136ad1cc516687a
Story: 2001457
Task: 6169

monasca_api/common/repositories/influxdb/metrics_repository.py

@@ -1,4 +1,4 @@
-# (C) Copyright 2014-2017 Hewlett Packard Enterprise Development LP
+# (C) Copyright 2014-2018 Hewlett Packard Enterprise Development LP
 # Copyright 2015 Cray Inc. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -777,7 +777,7 @@ class MetricsRepository(metrics_repository.AbstractMetricsRepository):
             if group_by:
                 items.extend(group_by)
             if period:
-                items.append("time(" + str(period) + "s)")
+                items.append("time(" + str(period) + "s) fill(none)")
             clause = " group by " + ','.join(items)
         else:
             clause = ""

monasca_api/tests/test_repositories.py

@@ -1,5 +1,5 @@
 # Copyright 2015 Cray Inc. All Rights Reserved.
-# (C) Copyright 2016-2017 Hewlett Packard Enterprise Development LP
+# (C) Copyright 2016-2018 Hewlett Packard Enterprise Development LP
 # Copyright 2017 Fujitsu LIMITED
 # (C) Copyright 2017 SUSE LLC
 #
@@ -131,6 +131,47 @@ class TestRepoMetricsInfluxDB(base.BaseTestCase):
             },
         }])
 
+    @patch('monasca_api.common.repositories.influxdb.'
+           'metrics_repository.client.InfluxDBClient')
+    def test_metrics_statistics(self, influxdb_client_mock):
+        mock_client = influxdb_client_mock.return_value
+        mock_client.query.return_value.raw = {
+            u'series': [{
+                u'values': [[
+                    u'1970-01-01T00:00:00Z', 0.047
+                ]],
+                u'name': u'cpu.utilization',
+                u'columns': [u'time', u'mean']}],
+            u'statement_id': 0
+        }
+
+        tenant_id = '1'
+        region = 'USA'
+        name = 'cpu.utilization'
+        start_timestamp = 1484036107.86
+        statistics = [u"avg"]
+        limit = 10000
+        dimensions = None
+        end_timestamp = None
+        period = None
+        offset = None
+        merge_metrics_flag = None
+        group_by = None
+
+        repo = influxdb_repo.MetricsRepository()
+        stats_list = repo.metrics_statistics(tenant_id, region, name,
+                                             dimensions, start_timestamp,
+                                             end_timestamp, statistics,
+                                             period, offset, limit,
+                                             merge_metrics_flag, group_by)
+        expected_result = [{
+            u'columns': [u'timestamp', u'avg'],
+            u'dimensions': {u'mean': 0.047, u'time': u'1970-01-01T00:00:00Z'},
+            u'id': '0',
+            u'name': u'cpu.utilization',
+            u'statistics': [[u'1970-01-01T00:00:00Z', 0.047]]}]
+        self.assertEqual(stats_list, expected_result)
+
     @patch("monasca_api.common.repositories.influxdb."
            "metrics_repository.client.InfluxDBClient")
     def test_list_dimension_values(self, influxdb_client_mock):

monasca_tempest_tests/tests/api/test_statistics.py

@@ -384,6 +384,25 @@ class TestStatistics(base.BaseMonascaTest):
                 self.assertEqual(200, resp.status)
                 self.assertEqual(expected_elements, response_body['elements'])
 
+    @decorators.attr(type="gate")
+    def test_list_statistics_with_long_start_time(self):
+        query_parms = '?name=' + str(self._test_name) + \
+                      '&statistics=' + urlparse.quote('avg,sum,min,max,count') + \
+                      '&start_time=' + "2017-01-01T00:00:00.00Z" + \
+                      '&end_time=' + str(self._end_time_iso) + \
+                      '&merge_metrics=true' + '&period=100000'
+        resp, response_body = self.monasca_client.list_statistics(
+            query_parms)
+        self.assertEqual(200, resp.status)
+        self.assertTrue(set(['links', 'elements']) == set(response_body))
+        element = response_body['elements'][0]
+        self._verify_element(element)
+        column = element['columns']
+        num_statistics_method = 5
+        statistics = element['statistics'][0]
+        self._verify_column_and_statistics(
+            column, num_statistics_method, statistics, self.metric_values)
+
     @decorators.attr(type="gate")
     @decorators.attr(type=['negative'])
     def test_list_statistics_with_no_merge_metrics(self):