Python dict with max size constraint

fifoDict.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# [email protected]

from collections import OrderedDict

class fifoDict:
    """OrderedDict with FIFO size constraint"""
    def __init__(self, size=1000, reducePc=0.2):
        self.od = OrderedDict()
        self.sz = size
        self.reducePc=0.5

    def add(self, item):
        if item not in self.od:
            self.od[item] = 0

    def getNew(self):
        newData = []
        markAsFetched = []
        for key, val in self.od.iteritems():
            if val == 0:
                newData.append( key )
        for key in newData:
            self.od[key] = 1
        #Reduce size of dict by reducePc % :
        if len(self.od) > self.sz:
            for i in range(int(self.reducePc * self.sz)):
                try:
                    self.od.popitem(last = False)
                except KeyError:
                    pass
        return newData