Got it. New PickleQueue class should be as follows:
import Queue
import cPickle
class PickleQueue(Queue.Queue):
"""A multi-producer, multi-consumer, persistent queue."""
def __init__(self, filename, maxsize=0):
"""Initialize a persistent queue with a filename and maximum
size.
The filename is used as a persistent data store for the
queue.
If maxsize <= 0, the queue size is infinite.
"""
self.filename = filename
Queue.Queue.__init__(self, maxsize)
print self.queue
def _init(self, maxsize):
# Implements Queue protocol _init for persistent queue.
# Sets up the pickle files.
self.maxsize = maxsize
try:
self.readfile = file(self.filename, 'r')
self.queue = cPickle.load(self.readfile)
self.readfile.close()
except IOError, err:
if err.errno == 2:
# File doesn't exist, continue ...
self.queue = Queue.deque()
else:
# Some other I/O problem, reraise error
raise err
except EOFError:
# File was null? Continue ...
self.queue = Queue.deque()
# Rewrite file, so it's created if it doesn't exist,
# and raises an exception now if we aren't allowed
self.writefile = file(self.filename, 'w')
cPickle.dump(self.queue, self.writefile, 1)
def __sync(self):
# Writes the queue to the pickle file.
self.writefile.seek(0)
cPickle.dump(self.queue, self.writefile, 1)
self.writefile.flush()
def _put(self, item):
# Implements Queue protocol _put for persistent queue.
self.queue.append(item)
self.__sync()
def _get(self):
# Implements Queue protocol _get for persistent queue.
item = self.queue.popleft()
self.__sync()
return item
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