send_receive_sync_helper.py

# Copyright 2021 Ricardo Mendes
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import asyncio


class SendReceiveSyncHelper:
    """Utility class with common features for handling messages/replies synchronization over
    WebSocket communication sessions.

    Attributes:
        __messages_history:
            A ``dict`` containing the full history of messages known by a given
            ``SendReceiveSyncHelper`` instance, represented as ``message-id: method`` items.
            It is automatically fulfilled when new stuff is added to ``__pending_reply_ids``.
        __pending_reply_ids:
            A ``list`` containing the ids of the pending replies, which means the messages
            identified by them were sent but not replied yet.
        __unhandled_replies:
            A ``list`` containing all replies that were received but not handled yet.
        __new_reply_event:
            A signal used by the receiver to notify the sender on the arrival of new replies, so
            the sender can take actions such as sending follow-up messages.
    """

    def __init__(self):
        self.__messages_history = {}
        self.__pending_reply_ids = []
        self.__unhandled_replies = []
        self.__new_reply_event = asyncio.Event()

    def add_pending_reply_id(self, message_id, method):
        self.__pending_reply_ids.append(message_id)
        self.__messages_history[message_id] = method

    def add_pending_reply_ids(self, message_ids, method):
        for message_id in message_ids:
            self.add_pending_reply_id(message_id, method)

    def remove_pending_reply_id(self, message_id):
        self.__pending_reply_ids.remove(message_id)

    def is_pending_reply(self, message_id, method):
        return message_id in self.__pending_reply_ids and self.is_method(message_id, method)

    def is_method(self, message_id, method):
        return method == self.__messages_history.get(message_id)

    def add_unhandled_reply(self, reply):
        self.__unhandled_replies.append(reply)

    def remove_unhandled_reply(self, reply):
        self.__unhandled_replies.remove(reply)

    def get_all_unhandled_replies(self):
        return self.__unhandled_replies

    def were_all_replies_processed(self):
        return not self.__pending_reply_ids and not self.__unhandled_replies

    def notify_new_reply(self):
        self.__new_reply_event.set()

    async def wait_for_replies(self):
        return await self.__new_reply_event.wait()

    def is_there_reply_notification(self):
        return self.__new_reply_event.is_set()

    def clear_reply_notifications(self):
        self.__new_reply_event.clear()