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# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of logilab-common.
#
# logilab-common is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option) any
# later version.
#
# logilab-common 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with logilab-common. If not, see <http://www.gnu.org/licenses/>.
"""Prioritized tasks queue"""
__docformat__ = "restructuredtext en"
from bisect import insort_left
from Queue import Queue
LOW = 0
MEDIUM = 10
HIGH = 100
PRIORITY = {
'LOW': LOW,
'MEDIUM': MEDIUM,
'HIGH': HIGH,
}
REVERSE_PRIORITY = dict((values, key) for key, values in PRIORITY.iteritems())
class PrioritizedTasksQueue(Queue):
def _init(self, maxsize):
"""Initialize the queue representation"""
self.maxsize = maxsize
# ordered list of task, from the lowest to the highest priority
self.queue = []
def _put(self, item):
"""Put a new item in the queue"""
for i, task in enumerate(self.queue):
# equivalent task
if task == item:
# if new task has a higher priority, remove the one already
# queued so the new priority will be considered
if task < item:
item.merge(task)
del self.queue[i]
break
# else keep it so current order is kept
task.merge(item)
return
insort_left(self.queue, item)
def _get(self):
"""Get an item from the queue"""
return self.queue.pop()
def __iter__(self):
return iter(self.queue)
def remove(self, tid):
"""remove a specific task from the queue"""
# XXX acquire lock
for i, task in enumerate(self):
if task.id == tid:
self.queue.pop(i)
return
raise ValueError('not task of id %s in queue' % tid)
class Task(object):
def __init__(self, tid, priority=LOW):
# task id
self.id = tid
# task priority
self.priority = priority
def __repr__(self):
return '<Task %s @%#x>' % (self.id, id(self))
def __cmp__(self, other):
return cmp(self.priority, other.priority)
def __lt__(self, other):
return self.priority < other.priority
def __eq__(self, other):
return self.id == other.id
def merge(self, other):
pass
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