Merge "Add a timeout object that can be interrupted"

taskflow/engines/worker_based/executor.py

@@ -42,7 +42,7 @@ class WorkerTaskExecutor(executor.TaskExecutorBase):
                                   self._on_wait, **kwargs)
         self._proxy_thread = None
         self._notify_thread = None
-        self._notify_event = threading.Event()
+        self._notify_timeout = misc.Timeout(pr.NOTIFY_PERIOD)
 
     def _make_thread(self, target):
         thread = threading.Thread(target=target)
@@ -167,9 +167,9 @@ class WorkerTaskExecutor(executor.TaskExecutorBase):
     def _notify_topics(self):
         """Cyclically publish notify message to each topic."""
         LOG.debug("Notify thread started.")
-        while not self._notify_event.is_set():
+        while not self._notify_timeout.is_stopped():
             self._proxy.publish(pr.Notify(), self._topics, reply_to=self._uuid)
-            self._notify_event.wait(pr.NOTIFY_PERIOD)
+            self._notify_timeout.wait()
 
     def execute_task(self, task, task_uuid, arguments,
                      progress_callback=None):
@@ -199,7 +199,7 @@ class WorkerTaskExecutor(executor.TaskExecutorBase):
         """Stop proxy, so its thread would be gracefully terminated."""
         if self._proxy_thread is not None:
             if self._proxy_thread.is_alive():
-                self._notify_event.set()
+                self._notify_timeout.interrupt()
                 self._notify_thread.join()
                 self._proxy.stop()
                 self._proxy_thread.join()

taskflow/utils/misc.py

@@ -25,6 +25,7 @@ import logging
 import os
 import string
 import sys
+import threading
 import time
 import traceback
 
@@ -210,6 +211,31 @@ class AttrDict(dict):
         self[name] = value
 
 
+class Timeout(object):
+    """An object which represents a timeout.
+
+    This object has the ability to be interrupted before the actual timeout
+    is reached.
+    """
+    def __init__(self, timeout):
+        if timeout < 0:
+            raise ValueError("Timeout must be >= 0 and not %s" % (timeout))
+        self._timeout = timeout
+        self._event = threading.Event()
+
+    def interrupt(self):
+        self._event.set()
+
+    def is_stopped(self):
+        return self._event.is_set()
+
+    def wait(self):
+        self._event.wait(self._timeout)
+
+    def reset(self):
+        self._event.clear()
+
+
 class ExponentialBackoff(object):
     """An iterable object that will yield back an exponential delay sequence
     provided an exponent and a number of items to yield. This object may be