Discarding FIFO queue, with max capacity, in Python?

Question

I need a discarding FIFO queue, that automatically discards items when it becomes full. It doesn't have to be thread-safe. Efficiency if more important. That is, I need to sample signals from a device while being able to retrieve the last n seconds (objects) at semi-random times. I have implemented a (not so thread-safe) buffer myself, but have the feeling I'm re-inventing the wheel here. In addition we are talking about a 100 objects every second. Most will be discarded while e.g. 3000 (= 30 secs of data) will have to be retrieved at a time (say every ten minutes). Is there such a class already in Python standard libs or elsewhere? I've used some goggle-fu but not managed to find anything useful. DiscardingBuffer ``` 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…

Accepted Answer

Use `collections.deque` specifying a `maxlen`,

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

Discarding FIFO queue, with max capacity, in Python?

Solution

Problem