I've a queue that is populated by different threads. I've a thread where I get items from the queue and I send them to another destination. When the last operation fails I want to put again the elements in the queue, but in the bottom of the queue because I want that the dequeuer Thread dequeue them as first priority. Is there a way to do that? Maybe using other class instead of Queue.queue?
How about a deque ?
Deques support thread-safe, memory efficient appends and pops from either side of the deque with approximately the same O(1) performance in either direction.
Here's an implementation -- it's basically Queue.put
method with self._put(item)
replaced by self.queue.appendleft(item)
from Queue import Queue
class MyQueue(Queue):
def putleft(self, item, block=True, timeout=None):
self.not_full.acquire()
try:
if self.maxsize > 0:
if not block:
if self._qsize() == self.maxsize:
raise Full
elif timeout is None:
while self._qsize() == self.maxsize:
self.not_full.wait()
elif timeout < 0:
raise ValueError("'timeout' must be a non-negative number")
else:
endtime = _time() + timeout
while self._qsize() == self.maxsize:
remaining = endtime - _time()
if remaining <= 0.0:
raise Full
self.not_full.wait(remaining)
self.queue.appendleft(item)
self.unfinished_tasks += 1
self.not_empty.notify()
finally:
self.not_full.release()
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