python之在 Python 中丢弃具有最大容量的 FIFO 队列

我需要一个丢弃 FIFO 队列，当它变满时自动丢弃项目。它不必是线程安全的。效率如果更重要的话。

也就是说，我需要对来自设备的信号进行采样，同时能够在半随机时间检索最后 n 秒(对象)。

我自己实现了一个(不是那么线程安全的)缓冲区，但感觉我正在重新发明轮子。此外，我们每秒谈论 100 个对象。大多数将被丢弃，例如必须一次检索 3000(= 30 秒的数据)(比如每十分钟一次)。

Python 标准库或其他地方是否已经存在这样的类？我使用了一些 goggle-fu，但未能找到任何有用的东西。

丢弃缓冲区

from Queue import Queue, Full, Empty 
import logging 
 
 
class DiscardingBuffer(): 
    def __init__(self, capacity=0): 
        self._queue = Queue(maxsize=capacity) 
 
    def put(self, item): 
        while True: 
            try: 
                self._queue.put(item, block=False) 
                logging.debug('Put item: {0}'.format(item)) 
                break 
            except Full: 
                discarded_item = self._queue.get(block=False) 
                logging.debug('Buffer is full. Discarding: {0}'.format(discarded_item)) 
 
    def flush(self): 
        items = [] 
 
        while True: 
            try: 
                items.append(self._queue.get(block=False)) 
            except Empty: 
                logging.debug('Buffer is now empty.') 
                break 
 
        return items 
 
 
def main(): 
    buf = DiscardingBuffer(5) 
 
    for i in xrange(10): 
        buf.put(i) 
 
    logging.debug('Remaining items: {0}'.format(buf.flush())) 
    logging.debug('Verify it is empty: {0}'.format(buf.flush())) 
 
 
if __name__ == '__main__': 
    logging.basicConfig(level=logging.DEBUG, 
                        format='[%(levelname)1.1s %(asctime)s %(name)s (%(process)d):%(lineno)d] %(message)s', 
                        datefmt='%Y-%m-%d %H:%M:%S') 
    main() 

输出

[D 2013-08-22 10:13:58 root (4164):13] Put item: 0 
[D 2013-08-22 10:13:58 root (4164):13] Put item: 1 
[D 2013-08-22 10:13:58 root (4164):13] Put item: 2 
[D 2013-08-22 10:13:58 root (4164):13] Put item: 3 
[D 2013-08-22 10:13:58 root (4164):13] Put item: 4 
[D 2013-08-22 10:13:58 root (4164):17] Buffer is full. Discarding: 0 
[D 2013-08-22 10:13:58 root (4164):13] Put item: 5 
[D 2013-08-22 10:13:58 root (4164):17] Buffer is full. Discarding: 1 
[D 2013-08-22 10:13:58 root (4164):13] Put item: 6 
[D 2013-08-22 10:13:58 root (4164):17] Buffer is full. Discarding: 2 
[D 2013-08-22 10:13:58 root (4164):13] Put item: 7 
[D 2013-08-22 10:13:58 root (4164):17] Buffer is full. Discarding: 3 
[D 2013-08-22 10:13:58 root (4164):13] Put item: 8 
[D 2013-08-22 10:13:58 root (4164):17] Buffer is full. Discarding: 4 
[D 2013-08-22 10:13:58 root (4164):13] Put item: 9 
[D 2013-08-22 10:13:58 root (4164):26] Buffer is now empty. 
[D 2013-08-22 10:13:58 root (4164):38] Remaining items: [5, 6, 7, 8, 9] 
[D 2013-08-22 10:13:58 root (4164):26] Buffer is now empty. 
[D 2013-08-22 10:13:58 root (4164):39] Verify it is empty: [] 

请您参考如下方法:

使用collections.deque指定一个 maxlen,

>>> q = deque(maxlen=2) 
>>> q.extend([1, 2, 3]) 
>>> q 
deque([2, 3], maxlen=2)