Fixed nasty concurrency bug in EC

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

diff --git a/src/nepi/execution/scheduler.py b/src/nepi/execution/scheduler.py
index 0060926..53a7530 100644 (file)
--- a/src/nepi/execution/scheduler.py
+++ b/src/nepi/execution/scheduler.py
@@ -1,3 +1,22 @@
+#
+#    NEPI, a framework to manage network experiments
+#    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.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# Author: Alina Quereilhac <alina.quereilhac@inria.fr>
+
 import itertools
 import heapq
 
@@ -8,6 +27,9 @@ class TaskStatus:
 
 
 class Task(object):
+    """ This class is to define a task, that is represented by an id,
+    an execution time 'timestamp' and an action 'callback """
+
     def __init__(self, timestamp, callback):
         self.id = None 
         self.timestamp = timestamp
@@ -16,9 +38,15 @@ class Task(object):
         self.status = TaskStatus.NEW
 
 class HeapScheduler(object):
-    """ 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 """
+    """ 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.
+
+    """
 
     def __init__(self):
         super(HeapScheduler, self).__init__()
@@ -27,20 +55,34 @@ class HeapScheduler(object):
         self._idgen = itertools.count(1)
 
     def schedule(self, task):
+        """ Add the task 'task' in the heap of the scheduler
+
+        :param task: task that need to be schedule
+        :type task: task
+        """
         if task.id == None:
             task.id = self._idgen.next()
+
         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
+
+        :param tid: Id of the task that need to be removed
+        :type tid: int
+        """
         try:
             self._valid.remove(tid)
         except:
             pass
 
     def next(self):
+        """ Get the next task in the scheduler
+
+        """
         while self._queue:
             try:
                 timestamp, tid, task = heapq.heappop(self._queue)