bpo-32025: Add time.thread_time() (#4410)

* bpo-32025: Add time.thread_time()

* Add missing #endif

* Add NEWS blurb

* Add docs and whatsnew

* Address review comments

* Review comments

1 files changed, 57 insertions, 0 deletions

diff --git a/Lib/test/test_time.py b/Lib/test/test_time.py
index b44646d..eda3885 100644
--- a/Lib/test/test_time.py
+++ b/Lib/test/test_time.py
@@ -47,6 +47,12 @@ ROUNDING_MODES = (
 )
 
 
+def busy_wait(duration):
+    deadline = time.monotonic() + duration
+    while time.monotonic() < deadline:
+        pass
+
+
 class TimeTestCase(unittest.TestCase):
 
     def setUp(self):
@@ -81,6 +87,10 @@ class TimeTestCase(unittest.TestCase):
         check_ns(time.process_time(),
                  time.process_time_ns())
 
+        if hasattr(time, 'thread_time'):
+            check_ns(time.thread_time(),
+                     time.thread_time_ns())
+
         if hasattr(time, 'clock_gettime'):
             check_ns(time.clock_gettime(time.CLOCK_REALTIME),
                      time.clock_gettime_ns(time.CLOCK_REALTIME))
@@ -486,10 +496,57 @@ class TimeTestCase(unittest.TestCase):
         # on Windows
         self.assertLess(stop - start, 0.020)
 
+        # process_time() should include CPU time spent in any thread
+        start = time.process_time()
+        busy_wait(0.100)
+        stop = time.process_time()
+        self.assertGreaterEqual(stop - start, 0.020)  # machine busy?
+
+        t = threading.Thread(target=busy_wait, args=(0.100,))
+        start = time.process_time()
+        t.start()
+        t.join()
+        stop = time.process_time()
+        self.assertGreaterEqual(stop - start, 0.020)  # machine busy?
+
         info = time.get_clock_info('process_time')
         self.assertTrue(info.monotonic)
         self.assertFalse(info.adjustable)
 
+    def test_thread_time(self):
+        if not hasattr(time, 'thread_time'):
+            if sys.platform.startswith(('linux', 'win')):
+                self.fail("time.thread_time() should be available on %r"
+                          % (sys.platform,))
+            else:
+                self.skipTest("need time.thread_time")
+
+        # thread_time() should not include time spend during a sleep
+        start = time.thread_time()
+        time.sleep(0.100)
+        stop = time.thread_time()
+        # use 20 ms because thread_time() has usually a resolution of 15 ms
+        # on Windows
+        self.assertLess(stop - start, 0.020)
+
+        # thread_time() should include CPU time spent in current thread...
+        start = time.thread_time()
+        busy_wait(0.100)
+        stop = time.thread_time()
+        self.assertGreaterEqual(stop - start, 0.020)  # machine busy?
+
+        # ...but not in other threads
+        t = threading.Thread(target=busy_wait, args=(0.100,))
+        start = time.thread_time()
+        t.start()
+        t.join()
+        stop = time.thread_time()
+        self.assertLess(stop - start, 0.020)
+
+        info = time.get_clock_info('thread_time')
+        self.assertTrue(info.monotonic)
+        self.assertFalse(info.adjustable)
+
     @unittest.skipUnless(hasattr(time, 'clock_settime'),
                          'need time.clock_settime')
     def test_monotonic_settime(self):