Python 可迭代队列

2022-01-21 00:00:00 python queue iteration

问题描述

我需要知道队列何时关闭并且不会有更多项目，以便我可以结束迭代.

I need to know when a Queue is closed and wont have more items so I can end the iteration.

我通过在队列中放置一个哨兵来做到这一点:

I did it by putting a sentinel in the queue:

from Queue import Queue

class IterableQueue(Queue): 

    _sentinel = object()

    def __iter__(self):
        return self

    def close(self):
        self.put(self._sentinel)

    def next(self):
        item = self.get()
        if item is self._sentinel:
            raise StopIteration
        else:
            return item

鉴于这是队列的一种非常常见的用途，难道没有任何内置实现吗?

Given that this is a very common use for a queue, isn't there any builtin implementation?

解决方案

sentinel 是生产者发送没有更多队列任务即将到来的消息的合理方式.

A sentinel is a reasonable way for a producer to send a message that no more queue tasks are forthcoming.

FWIW，您的代码可以使用 iter():

FWIW, your code can be simplified quite a bit with the two argument form of iter():

from Queue import Queue

class IterableQueue(Queue): 

    _sentinel = object()

    def __iter__(self):
        return iter(self.get, self._sentinel)

    def close(self):
        self.put(self._sentinel)

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