Fix win_pdh.get_counters failing when no data are available

changelog/58327.fixed

@@ -0,0 +1 @@
+Return empty dict on win_pdh.get_counters rather than raising exception when no data are available

salt/utils/win_pdh.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 r"""
 Salt Util for getting system information with the Performance Data Helper (pdh).
 Counter information is gathered from current activity or log files.
@@ -35,7 +34,6 @@ Usage:
 
 # https://docs.microsoft.com/en-us/windows/desktop/perfctrs/using-the-pdh-functions-to-consume-counter-data
 # Import python libs
-from __future__ import absolute_import, unicode_literals
 
 # https://www.cac.cornell.edu/wiki/index.php?title=Performance_Data_Helper_in_Python_with_win32pdh
 import logging
@@ -74,7 +72,7 @@ def __virtual__():
     return __virtualname__
 
 
-class Counter(object):
+class Counter:
     """
     Counter object
     Has enumerations and functions for working with counters
@@ -172,7 +170,7 @@ class Counter(object):
         )
         if win32pdh.ValidatePath(path) == 0:
             return Counter(path, obj, instance, instance_index, counter)
-        raise CommandExecutionError("Invalid counter specified: {0}".format(path))
+        raise CommandExecutionError("Invalid counter specified: {}".format(path))
 
     build_counter = staticmethod(build_counter)
 
@@ -421,6 +419,14 @@ def get_counters(counter_list):
                 else:
                     raise
 
+    except pywintypes.error as exc:
+        if exc.strerror == "No data to return.":
+            # Sometimess, win32pdh.CollectQueryData can err
+            # so just ignore it
+            return {}
+        else:
+            raise
+
     finally:
         win32pdh.CloseQuery(query)
 

tests/unit/utils/test_win_pdh.py

@@ -1,12 +1,18 @@
-# -*- coding: utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import salt.utils.platform
 import salt.utils.win_pdh as win_pdh
 from tests.support.helpers import slowTest
+from tests.support.mock import patch
 from tests.support.unit import TestCase, skipIf
 
+try:
+    import pywintypes
 
+    HAS_WIN32 = True
+except ImportError:
+    HAS_WIN32 = False
+
+
+@skipIf(not HAS_WIN32, "Requires pywin32")
 @skipIf(not salt.utils.platform.is_windows(), "System is not Windows")
 class WinPdhTestCase(TestCase):
     @slowTest
@@ -95,3 +101,19 @@ class WinPdhTestCase(TestCase):
     def test_get_counter(self):
         results = win_pdh.get_counter("Processor", "*", "% Processor Time")
         self.assertTrue("\\Processor(*)\\% Processor Time" in results)
+
+    @patch("win32pdh.CollectQueryData")
+    def test_get_counters_no_data_to_return(self, mock_query):
+        mock_query.side_effect = pywintypes.error(
+            -2147481643, "CollectQueryData", "No data to return."
+        )
+        counter_list = [
+            ("Memory", None, "Available Bytes"),
+            ("Paging File", "*", "% Usage"),
+            ("Processor", "*", "% Processor Time"),
+            ("Server", None, "Work Item Shortages"),
+            ("Server Work Queues", "*", "Queue Length"),
+            ("System", None, "Context Switches/sec"),
+        ]
+        results = win_pdh.get_counters(counter_list)
+        assert results == {}