new clock() using internal Python API

PyMPDATA/impl/clock.py

@@ -1,17 +1,7 @@
-""" CPU-time returning clock() function which works from within njit-ted code """
+""" CPU-time returning clock() function which works from within njit-ted code,
+    no time unit guaranteed, returned value only for relative time measurements """
 import ctypes
-import platform
 
-if platform.system() == "Windows":
-    from ctypes.util import find_msvcrt
-
-    __LIB = find_msvcrt()
-    if __LIB is None:
-        __LIB = "msvcrt.dll"
-else:
-    from ctypes.util import find_library
-
-    __LIB = find_library("c")
-
-clock = ctypes.CDLL(__LIB).clock
+clock = ctypes.pythonapi._PyTime_GetSystemClock
 clock.argtypes = []
+clock.restype = ctypes.c_int64

tests/smoke_tests/olesik_et_al_2022/test_wall_time.py

@@ -1,10 +1,6 @@
 # pylint: disable=missing-module-docstring,missing-class-docstring,missing-function-docstring
-import os
-
-import pytest
 from PyMPDATA_examples.Olesik_et_al_2022 import wall_time
 
 
-@pytest.mark.xfail(condition=os.name == "nt")
 def test_wall_time():
     wall_time.test_wall_time()

tests/unit_tests/test_clock.py

@@ -33,13 +33,16 @@ def test():
     @staticmethod
     def test_clock_value():
         # Arrange
-        sec_expected = 2
+        factor = 3
+        base = 0.01
         start = clock()
+        time.sleep(base)
+        sec_one = clock() - start
 
         # Act
-        time.sleep(sec_expected)
-        stop = clock()
+        start = clock()
+        time.sleep(base * factor)
+        sec_two = clock() - start
 
         # Assert
-        sec_actual = (stop - start) / 1000
-        assert (sec_actual - sec_expected) / sec_expected < 0.1
+        assert abs(sec_two / sec_one - factor) < 0.1