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[nepi.git] / src / nepi / execution / scheduler.py

diff --git a/src/nepi/execution/scheduler.py b/src/nepi/execution/scheduler.py
index 1b35362..e07ba75 100644 (file)
--- a/src/nepi/execution/scheduler.py
+++ b/src/nepi/execution/scheduler.py
@@ -3,9 +3,8 @@
 #    Copyright (C) 2013 INRIA
 #
 #    This program is free software: you can redistribute it and/or modify
-#    it under the terms of the GNU General Public License as published by
-#    the Free Software Foundation, either version 3 of the License, or
-#    (at your option) any later version.
+#    it under the terms of the GNU General Public License version 2 as
+#    published by the Free Software Foundation;
 #
 #    This program is distributed in the hope that it will be useful,
 #    but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -17,20 +16,32 @@
 #
 # Author: Alina Quereilhac <alina.quereilhac@inria.fr>
 
+from six import next
+
 import itertools
 import heapq
 
 class TaskStatus:
+    """ Execution state of the Task
+    """
     NEW = 0
     DONE = 1
     ERROR = 2
 
-
 class Task(object):
-    """ This class is to define a task, that is represented by an id,
-    an execution time 'timestamp' and an action 'callback """
+    """ A Task represents an operation to be executed by the 
+    ExperimentController scheduler
+    """
 
     def __init__(self, timestamp, callback):
+        """
+        :param timestamp: Future execution date of the operation
+        :type timestamp: str
+
+        :param callback: A function to invoke in order to execute the operation
+        :type callback: function
+
+        """ 
         self.id = None 
         self.timestamp = timestamp
         self.callback = callback
@@ -38,13 +49,15 @@ class Task(object):
         self.status = TaskStatus.NEW
 
 class HeapScheduler(object):
-    """ Create a Heap Scheduler.
+    """ Create a Heap Scheduler
 
     .. note::
 
-    This class is thread safe.
-    All calls to C Extensions are made atomic by the GIL in the CPython implementation.
-    heapq.heappush, heapq.heappop, and list access are therefore thread-safe """
+        This class is thread safe.
+        All calls to C Extensions are made atomic by the GIL in the CPython implementation.
+        heapq.heappush, heapq.heappop, and list access are therefore thread-safe.
+
+    """
 
     def __init__(self):
         super(HeapScheduler, self).__init__()
@@ -52,33 +65,43 @@ class HeapScheduler(object):
         self._valid = set()
         self._idgen = itertools.count(1)
 
+    @property
+    def pending(self):
+        """ Returns the list of pending task ids """
+        return self._valid
+
     def schedule(self, task):
-        """ Add the task 'task' in the heap of the scheduler
+        """ Add a task to the queue ordered by task.timestamp and arrival order
 
-        :param task: task that need to be schedule
+        :param task: task to schedule
         :type task: task
         """
         if task.id == None:
-            task.id = self._idgen.next()
+            task.id = next(self._idgen)
+
         entry = (task.timestamp, task.id, task)
         self._valid.add(task.id)
         heapq.heappush(self._queue, entry)
         return task
 
     def remove(self, tid):
-        """ Remove a task form the heap
+        """ Remove a task form the queue
 
-        :param tid: Id of the task that need to be removed
+        :param tid: Id of the task to be removed
         :type tid: int
+
         """
         try:
             self._valid.remove(tid)
         except:
             pass
 
-    def next(self):
-        """ Get the next task in the scheduler
+    # py3 compat
+    def __next__(self):
+        return self.next()
 
+    def next(self):
+        """ Get the next task in the queue by timestamp and arrival order
         """
         while self._queue:
             try: