update perf count to ignore case (#22028)

* update perf count to ignore case

* change log

* add tests

* update tests

* lint

* fix test

Author: jack0x2

datadog_checks_base/changelog.d/22028.fixed

@@ -0,0 +1 @@
+Updates perf counters to ignore case. Fixes an error with double counting in exchange.activemanager.database_mounted metric.

datadog_checks_base/datadog_checks/base/checks/windows/perf_counters/counter.py

@@ -51,7 +51,9 @@ def __init__(self, check, connection, name, config, use_localized_counters, tags
                         f'Pattern #{i} of option `include` for performance object `{self.name}` must be a string'
                     )
 
-            self.include_pattern = re.compile('|'.join(include_patterns))
+            # Instance names are not case-sensitive, so instances should not have names that differ only in case.
+            # See: https://learn.microsoft.com/en-us/windows/win32/perfctrs/about-performance-counters
+            self.include_pattern = re.compile('|'.join(include_patterns), re.IGNORECASE)
 
         # List of regex patterns to filter multi-instance counters AFTER ALL data
         # is collected and retrieved from PDH layer
@@ -67,7 +69,9 @@ def __init__(self, check, connection, name, config, use_localized_counters, tags
 
             final_exclude_patterns = [r'\b_Total\b']
             final_exclude_patterns.extend(exclude_patterns)
-            self.exclude_pattern = re.compile('|'.join(final_exclude_patterns))
+            # Instance names are not case-sensitive, so instances should not have names that differ only in case.
+            # See: https://learn.microsoft.com/en-us/windows/win32/perfctrs/about-performance-counters
+            self.exclude_pattern = re.compile('|'.join(final_exclude_patterns), re.IGNORECASE)
 
         # List of wildcards or instance name directly to filter multi-instance counters by PDH layer itself.
         # Thus it is faster and and less resource intensive than regex-based include filtering.

datadog_checks_base/tests/base/checks/windows/perf_counters/test_filter.py

@@ -49,3 +49,29 @@ def test_exclude_default(aggregator, dd_run_check, mock_performance_objects):
     dd_run_check(check)
 
     aggregator.assert_all_metrics_covered()
+
+
+def test_exclude_case_insensitive(aggregator, dd_run_check, mock_performance_objects):
+    mock_performance_objects({'Foo': (['0,_total', 'baz'], {'Bar': [1, 2]})})
+    check = get_check({'metrics': {'Foo': {'name': 'foo', 'exclude': ['Baz'], 'counters': [{'Bar': 'bar'}]}}})
+    dd_run_check(check)
+
+    aggregator.assert_all_metrics_covered()
+
+
+def test_include_case_insensitive(aggregator, dd_run_check, mock_performance_objects):
+    mock_performance_objects({'Foo': (['Foobar', 'Bar', 'Barbat'], {'Bar': [1, 2, 3]})})
+    check = get_check({'metrics': {'Foo': {'name': 'foo', 'include': ['bar$'], 'counters': [{'Bar': 'bar'}]}}})
+    dd_run_check(check)
+
+    tags = ['instance:Foobar']
+    tags.extend(GLOBAL_TAGS)
+    aggregator.assert_metric('test.foo.bar', 1, tags=tags)
+
+    tags = ['instance:Bar']
+    tags.extend(GLOBAL_TAGS)
+    aggregator.assert_metric('test.foo.bar', 2, tags=tags)
+
+    aggregator.assert_metric_has_tag('test.foo.bar', 'instance:Barbat', count=0)
+
+    aggregator.assert_all_metrics_covered()

exchange_server/tests/test_unit.py

@@ -46,7 +46,7 @@ def test(aggregator, dd_default_hostname, dd_run_check, mock_performance_objects
                     if instance is None:
                         tags = global_tags
                     else:
-                        if '_Total' in instance:
+                        if '_total' in instance.lower():
                             continue
 
                         tags = ['instance:{}'.format(instance)]