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"""Prioritized tasks queue
:organization: Logilab
:copyright: 2008 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
"""
__docformat__ = "restructuredtext en"
from bisect import insort_left
from Queue import Queue
LOW = 0
MEDIUM = 10
HIGH = 100
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 __eq__(self, other):
return self.id == other.id
def merge(self, other):
pass
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