libasynctasks: fixed a bug with delayed tasks which caused them to lay in the task manager's queue forever

Author: cmarshall108

src/libasynctasks.pyx

@@ -189,12 +189,14 @@ class TaskScheduler(threading.Thread):
 
     __slots__ = (
         '_task_manager',
+        '_mutex_lock',
         '_shutdown',
         '_task_queue'
     )
 
     def __init__(self, task_manager):
         self._task_manager = task_manager
+        self._mutex_lock = threading.RLock()
 
         self._shutdown = False
         self._task_queue = collections.deque()
@@ -300,21 +302,23 @@ class TaskScheduler(threading.Thread):
             return
         elif result == TASK_WAIT:
             task.can_delay = True
+            # since this task is delayed, we need to keep it on it's original
+            # thread; otherwise our thread will be killed and the task will
+            # float in oblivion forever...
+            self._task_queue.append(task)
         elif result == TASK_CONT:
             task.can_delay = False
+            # add this task back to the task manager's queue so it can
+            # be ran on another thread if another one is available and has
+            # even less currently running tasks on it...
+            self._task_manager.task_queue.append(task)
         else:
             # check to see if we got any other result than what we
             # are expecting, tasks do not return values when they are called
             # like a normal function... So we should never expect this to be the case.
             raise TaskError('Got invalid result <%r> when running task <%s>!' % (
                 result, task.name))
 
-        # the task want's to be placed back into the queue,
-        # instead of waiting for a new scheduler to be created,
-        # let's just add this task back to our own scheduler so we
-        # can save time between each execution...
-        self._task_manager.task_queue.append(task)
-
         # finally let's check to see if we have any tasks remaining
         # in the task queue, if we do not; then this means we have
         # served our purpose and is no longer needed...
@@ -329,16 +333,20 @@ class TaskScheduler(threading.Thread):
         """
 
         while not self._shutdown:
-            try:
-                self.update()
-            except (KeyboardInterrupt, SystemExit):
-                break
+            # acquire the mutex lock so we don't change the queue
+            # during it's iteration on the other thread...
+            with self._mutex_lock:
+                try:
+                    self.update()
+                except (KeyboardInterrupt, SystemExit):
+                    break
 
             thread_wait()
 
         self._task_manager.remove_scheduler(self)
 
     def __del__(self):
+        self._mutex_lock = None
         self._task_queue = None