#
# 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 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
# 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 .
#
# Author: Alina Quereilhac
from six import next
import itertools
import heapq
class TaskStatus:
""" Execution state of the Task
"""
NEW = 0
DONE = 1
ERROR = 2
class Task(object):
""" 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
self.result = None
self.status = TaskStatus.NEW
class HeapScheduler(object):
""" 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__()
self._queue = list()
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 a task to the queue ordered by task.timestamp and arrival order
:param task: task to schedule
:type task: task
"""
if task.id == None:
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 queue
:param tid: Id of the task to be removed
:type tid: int
"""
try:
self._valid.remove(tid)
except:
pass
# 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:
timestamp, tid, task = heapq.heappop(self._queue)
if tid in self._valid:
self.remove(tid)
return task
except IndexError:
# heap empty
pass
return None