from queue import Queue
from typing_extensions import Buffer
[docs]
class Outbox:
"""Stores messages to be sent to a particular receiver.
An Outbox is a queue of messages, which may be deposited and
then retrieved in the same order.
"""
def __init__(self) -> None:
"""Create an empty Outbox.
"""
self.__queue: Queue[Buffer] = Queue()
[docs]
def is_empty(self) -> bool:
"""Returns True iff the outbox is empty.
"""
return self.__queue.empty()
[docs]
def deposit(self, message: Buffer) -> None:
"""Put a message in the Outbox.
The message will be placed at the back of a queue, and may be
retrieved later via :py:meth:`retrieve`.
Args:
message: The message to store.
"""
self.__queue.put(message)
[docs]
def retrieve(self) -> Buffer:
"""Retrieve a message from the Outbox.
The message will be removed from the front of the queue, and
returned to the caller. Blocks if the queue is empty, until a
message is deposited.
Returns:
The next message.
"""
return self.__queue.get()