amq-adapter-python/amqp/router/router_producer.py

"""
* Maps the request to RabbitMQ exchange. Handles the service discovery logic.
*
* Router can be either in 'Master' or 'Service (Consumer)' modes. 'Master' mode is the outward
* facing side that receives the requests and routes it to queue associated with requested service.
* 'Service' mode is consumer side for given service, which receives the message from AMQ and
* forwards it to the application.
"""

from aio_pika import Message
from aio_pika.abc import (
    AbstractIncomingMessage,
    AbstractRobustChannel,
    AbstractRobustConnection,
    AbstractRobustExchange,
    AbstractRobustQueue,
)
from pika.exchange_type import ExchangeType

from amqp.adapter.logging_utils import (
    logging_debug,
    logging_error,
    logging_info,
    logging_warning,
)
from amqp.adapter.service_message_factory import ServiceMessageFactory
from amqp.config.amq_configuration import AMQConfiguration
from amqp.model.model import ServiceMessage
from amqp.model.service_message_type import ServiceMessageType
from amqp.router.router_base import (
    ANY_RECIPIENT,
    CM_C_AMQ_QUEUE,
    CM_P_REPLY_TO,
    CM_P_RESP_QUEUE,
    CM_REQUEST_EXCHANGE,
    CM_RESPONSE_EXCHANGE,
    RouterBase,
)


class RouterProducer(RouterBase):

    def __init__(self, configuration: AMQConfiguration):
        """
        * Initialize router - need to supply the config values and RabbitMQ channel.
        * :param configuration:  adapter's configuration reference.
        """
        super().__init__()
        self.connection: AbstractRobustConnection | None = None
        self.service_message_factory = ServiceMessageFactory(configuration.amq_adapter.service_name)
        self.amq_configuration: AMQConfiguration = configuration
        self.channel: AbstractRobustChannel | None = None
        self.cm_request_exchange: AbstractRobustExchange | None = None
        self.cm_response_exchange: AbstractRobustExchange | None = None

        logging_info(
            "RouterProducer.<init>: %s, route: %s",
            self.amq_configuration.amq_adapter.service_name,
            self.amq_configuration.amq_adapter.route_mapping,
        )

    async def init_internal_routing_paths(self, channel: AbstractRobustChannel | None):
        """
        * Initialize internal routes for ServiceMessages.
        * The logic here sets a producer and listener on CleverMicroRequest/CleverMicroResponse queues
        * created to enable the service discovery.
        * The Producer mode sends out routing data request on CleverMicroRequest and listens
        * on CleverMicroResponse for any service responding with its routing data.
        """

        self.channel = channel
        logging_info(
            "RouterProducer.initRoutingPaths, channel open: %s",
            self.is_open(self.channel),
        )
        if self.is_open(self.channel):
            try:
                # **** set up the service discovery internal exchanges ****
                # 1. declare RequestExchange to where to publish the RoutingData requests
                self.cm_request_exchange = await self.channel.declare_exchange(
                    name=CM_REQUEST_EXCHANGE, type=ExchangeType.fanout
                )
                #
                # 2. declare ResponseExchange where to publish current_availability RoutingData (response to
                #    a RoutingData request)
                self.cm_response_exchange = await self.channel.declare_exchange(
                    name=CM_RESPONSE_EXCHANGE, type=ExchangeType.fanout
                )
                # 2a. declare a Response queue for Routing Data replies from Services
                _cm_response_queue: str = self.get_response_queue_name()
                _response_queue: AbstractRobustQueue = await self.channel.declare_queue(
                    name=_cm_response_queue,
                    durable=True,
                    exclusive=False,
                    auto_delete=False,
                    arguments={},
                )
                # 2b. bind queue to CM_RESPONSE_EXCHANGE w/o any conditions (empty routing key)
                await _response_queue.bind(exchange=CM_RESPONSE_EXCHANGE, routing_key="#")
                # 2c. listen for incoming RoutingData messages
                _c_tag = await _response_queue.consume(
                    callback=self.handle_routing_data_message, no_ack=False
                )
                logging_info(
                    " [%s] Routing master listens for Route updates on %s",
                    _c_tag,
                    _cm_response_queue,
                )
            except Exception as ioe:
                logging_error("RouterProducer FATAL: cannot initialize, %s", ioe)

        else:
            logging_error("RouterProducer FATAL: cannot initialize, RabbitMQ channel is not open.")

    async def handle_routing_data_message(self, message: AbstractIncomingMessage):
        """
        * Handler for CLEVER_MICRO_RESPONSE queue messages. Used in Master mode to handle receipt of
        * routing data, invokes addRoute or removeRoute depending on the type of the message.
        """
        logging_info(
            "[%s] Received ROUTING DATA: [%s], msgId=%s",
            message.delivery_tag,
            message.body,
            message.message_id,
        )
        await message.ack(multiple=False)
        cm_message: ServiceMessage = self.service_message_factory.from_bytes(message.body)
        # ignore the message if it comes from ourselves (even if from different instance)
        logging_debug(
            "******[%s] ROUTING_DATA, msg=%s, routeMap=[%s] sn=%s, replyTo=%s",
            message.delivery_tag,
            self.service_message_factory.to_string(cm_message),
            self.amq_configuration.amq_adapter.route_mapping,
            self.amq_configuration.amq_adapter.service_name,
            cm_message.reply_to,
        )
        if (
            cm_message.is_valid()
            and not self.amq_configuration.amq_adapter.service_name == cm_message.reply_to
        ):
            if cm_message.message_type == ServiceMessageType.ROUTING_DATA:
                self.add_routes(cm_message.message)
            if cm_message.message_type == ServiceMessageType.ROUTING_DATA_REMOVE:
                self.remove_routes(cm_message.message)

    async def request_routes_from_adapters(self):
        """
        * Send a broadcast message prompting all listening adapters to reply with own routing data.
        """
        logging_info(
            "RouterProducer.requestRoutesFromAdapters, queue name: %s",
            CM_REQUEST_EXCHANGE,
        )
        try:
            serviceMessage: ServiceMessage = self.service_message_factory.of(
                ServiceMessageType.ROUTING_DATA_REQUEST, "", ANY_RECIPIENT
            )
            if not await self.publish_service_message(serviceMessage, self.cm_request_exchange):
                logging_warning(
                    "RouterProducer could not request route data: %s channel is not open.",
                    CM_REQUEST_EXCHANGE,
                )

        except Exception as ioe:
            logging_error("RouterProducer failed request routing data: %s", ioe)

    async def publish_service_message(
        self, message: ServiceMessage, exchange: AbstractRobustExchange
    ) -> bool:
        """
        * Publishes a service message to the service queue and logs success log entry.
        *
        * :param message:   Service Message to be sent
        * :param exchange: target exchange name where to publish the message
        * :return True if channel is open, False otherwise
        * @throws IOException if something else goes wrong
        """
        if self.is_open(self.channel):
            binary_content: bytes = self.service_message_factory.serialize(message)
            pika_message: Message = Message(
                body=binary_content,
                content_encoding="utf-8",
                delivery_mode=2,
                content_type="application/octet-stream",
                headers=None,
                priority=0,
                correlation_id=None,
            )
            await exchange.publish(message=pika_message, routing_key="")
            logging_info(
                "Service Message Published to %s, msg: %s",
                exchange.name,
                str(binary_content),
            )
            return True
        return False

    def get_reply_to_queue_name(self) -> str:
        """
        * self should create a unique name for self process and also when there's several instances.
        * @return unique reply-to queue name.
        """
        return self.amq_configuration.amq_adapter.adapter_prefix() + CM_P_REPLY_TO

    def get_response_queue_name(self) -> str:
        """
        * self should create a unique name for self process and also when there's several instances.
        * @return unique reply-to queue name.
        """
        return self.amq_configuration.amq_adapter.adapter_prefix() + CM_P_RESP_QUEUE

    def get_consume_queue_name(self) -> str:
        """
        * self should create a unique name for self process and also when there's several instances.
        * @return unique reply-to queue name.
        """
        return self.amq_configuration.amq_adapter.adapter_prefix() + CM_C_AMQ_QUEUE

    def is_open(self, _channel: AbstractRobustChannel) -> bool:
        """
        * Test if the channel is usable (opened).
        * :param _channel: the channel
        * :return True if the channel is opened.
        """
        return _channel is not None and not _channel.is_closed