Add ability to cancel Threads and ThreadGroups

Change-Id: I4d5eb361fd1820b4fe8501df6fe2a03c49e816b3
Partial-Bug: #1536451

oslo_service/tests/test_threadgroup.py

@@ -93,6 +93,35 @@ class ThreadGroupTestCase(test_base.BaseTestCase):
         self.assertEqual(0, len(self.tg.threads))
         self.assertTrue(end_time - start_time >= 1)
 
+    def test_cancel_early(self):
+
+        def foo(*args, **kwargs):
+            time.sleep(1)
+        self.tg.add_thread(foo, 'arg', kwarg='kwarg')
+        self.tg.cancel()
+
+        self.assertEqual(0, len(self.tg.threads))
+
+    def test_cancel_late(self):
+
+        def foo(*args, **kwargs):
+            time.sleep(0.3)
+        self.tg.add_thread(foo, 'arg', kwarg='kwarg')
+        time.sleep(0)
+        self.tg.cancel()
+
+        self.assertEqual(1, len(self.tg.threads))
+
+    def test_cancel_timeout(self):
+
+        def foo(*args, **kwargs):
+            time.sleep(0.3)
+        self.tg.add_thread(foo, 'arg', kwarg='kwarg')
+        time.sleep(0)
+        self.tg.cancel(timeout=0.2, wait_time=0.1)
+
+        self.assertEqual(0, len(self.tg.threads))
+
     def test_stop_timers(self):
 
         def foo(*args, **kwargs):

oslo_service/threadgroup.py

@@ -13,6 +13,7 @@
 #    under the License.
 import logging
 import threading
+import time
 
 import eventlet
 from eventlet import greenpool
@@ -58,6 +59,9 @@ class Thread(object):
     def link(self, func, *args, **kwargs):
         self.thread.link(func, *args, **kwargs)
 
+    def cancel(self, *throw_args):
+        self.thread.cancel(*throw_args)
+
 
 class ThreadGroup(object):
     """The point of the ThreadGroup class is to:
@@ -154,3 +158,31 @@ class ThreadGroup(object):
         self._perform_action_on_threads(
             lambda x: x.wait(),
             lambda x: LOG.exception(_LE('Error waiting on thread.')))
+
+    def _any_threads_alive(self):
+        current = threading.current_thread()
+        for x in self.threads[:]:
+            if x.ident == current.ident:
+                # Don't check current thread.
+                continue
+            if not x.thread.dead:
+                return True
+        return False
+
+    def cancel(self, *throw_args, **kwargs):
+        self._perform_action_on_threads(
+            lambda x: x.cancel(*throw_args),
+            lambda x: LOG.exception(_LE('Error canceling thread.')))
+
+        timeout = kwargs.get('timeout', None)
+        if timeout is None:
+            return
+        wait_time = kwargs.get('wait_time', 1)
+        start = time.time()
+        while self._any_threads_alive():
+            run_time = time.time() - start
+            if run_time < timeout:
+                eventlet.sleep(wait_time)
+                continue
+            LOG.debug("Cancel timeout reached, stopping threads.")
+            self.stop()