timeBasedProcessingQueue.py

#!/usr/bin/env python

import threading
import time

# Uses earliest allowed processing timestamp to sort items in the queue
# Queued item will not be processed until its earliest allowed processing 
# timestamp has passed
class TimeBasedProcessingQueue:

    def __init__(self):
        self.lock = threading.RLock()
        self.queue = []
        self.itemPopTimeList = []

    def push(self, item, itemProcessingWaitTime=0):
        self.lock.acquire()
        try:
            earliestPopTime = time.time() + itemProcessingWaitTime
            popIndex = 0
            for t in self.itemPopTimeList:
                if earliestPopTime <= t:
                    break
                popIndex += 1
            self.itemPopTimeList.insert(popIndex, earliestPopTime)
            self.queue.insert(popIndex,item)
        finally:
            self.lock.release()

    def pop(self):
        # Return None if work queue is empty.
        self.lock.acquire()
        try:
            item = None
            if len(self.queue):
                if self.itemPopTimeList[0] <= time.time():
                    del self.itemPopTimeList[0]
                    item = self.queue[0]
                    del self.queue[0]
            return item
        finally:
            self.lock.release()

    def getLength(self):
        return len(self.queue)

    def isEmpty(self):
        return len(self.queue) == 0

####################################################################
# Testing

if __name__ == '__main__':
    import random
    q = TimeBasedProcessingQueue()
    for i in range(0,10000000):
        waitTime = random.uniform(0,10)
        q.push(i, waitTime)
        #print 'Added: ', i, '; Processing wait: ', waitTime

    print "Sleeping..."
    time.sleep(60)
    print "Removing..."
    while not q.isEmpty():
        i = q.pop() 
        #print 'Got: ', i
        #time.sleep(1)
    print "Sleeping..."
    time.sleep(60)