pyinfra/pyinfra/queue/queue_manager/pika_queue_manager.py

import json
import logging

import pika

from pyinfra.config import CONFIG
from pyinfra.exceptions import ProcessingFailure
from pyinfra.queue.queue_manager.queue_manager import QueueHandle, QueueManager

logger = logging.getLogger("pika")
logger.setLevel(logging.WARNING)

logger = logging.getLogger(__name__)
logger.setLevel(CONFIG.service.logging_level)


def monkey_patch_queue_handle(channel, queue) -> QueueHandle:

    empty_message = (None, None, None)

    def is_empty_message(message):
        return message == empty_message

    queue_handle = QueueHandle()
    queue_handle.empty = lambda: is_empty_message(channel.basic_get(queue))

    def produce_items():

        while True:
            message = channel.basic_get(queue)

            if is_empty_message(message):
                break

            method_frame, properties, body = message
            channel.basic_ack(method_frame.delivery_tag)
            yield json.loads(body)

    queue_handle.to_list = lambda: list(produce_items())

    return queue_handle


def get_connection():

    credentials = pika.PlainCredentials(username=CONFIG.rabbitmq.user, password=CONFIG.rabbitmq.password)

    kwargs = {"host": CONFIG.rabbitmq.host, "port": CONFIG.rabbitmq.port, "credentials": credentials}

    parameters = pika.ConnectionParameters(**kwargs)

    connection = pika.BlockingConnection(parameters=parameters)

    return connection


def get_n_previous_attempts(props):
    return 0 if props.headers is None else props.headers.get("x-retry-count", 0)


def attempts_remain(n_attempts, max_attempts):
    return n_attempts < max_attempts


class PikaQueueManager(QueueManager):
    def __init__(self, input_queue, output_queue, dead_letter_queue=None):
        super().__init__(input_queue, output_queue)

        self.connection = get_connection()
        self.channel = self.connection.channel()

        if not dead_letter_queue:
            dead_letter_queue = CONFIG.rabbitmq.queues.dead_letter

        args = {"x-dead-letter-exchange": "", "x-dead-letter-routing-key": dead_letter_queue}

        self.channel.queue_declare(input_queue, arguments=args, auto_delete=False)
        self.channel.queue_declare(output_queue, arguments=args, auto_delete=False)

    def republish(self, body, n_current_attempts, frame):
        self.channel.basic_publish(
            exchange="",
            routing_key=self._input_queue,
            body=body,
            properties=pika.BasicProperties(headers={"x-retry-count": n_current_attempts}),
        )
        self.channel.basic_ack(delivery_tag=frame.delivery_tag)

    def publish_request(self, request):
        logger.debug(f"Publishing {request}")
        self.channel.basic_publish("", self._input_queue, json.dumps(request).encode())

    def reject(self, body, frame):
        logger.exception(f"Adding to dead letter queue: {body}")
        self.channel.basic_reject(delivery_tag=frame.delivery_tag, requeue=False)

    def publish_response(self, message, callback, max_attempts=3):

        logger.debug(f"Publishing response for {message}.")

        frame, properties, body = message

        n_attempts = get_n_previous_attempts(properties) + 1

        try:
            response = json.dumps(callback(json.loads(body)))
            self.channel.basic_publish("", self._output_queue, response.encode())
            self.channel.basic_ack(frame.delivery_tag)
        except ProcessingFailure:

            logger.error(f"Message failed to process {n_attempts}/{max_attempts} times: {body}")

            if attempts_remain(n_attempts, max_attempts):
                self.republish(body, n_attempts, frame)
            else:
                self.reject(body, frame)

    def pull_request(self):
        return self.channel.basic_get(self._input_queue)

    def consume(self):
        logger.debug("Consuming")
        return self.channel.consume(self._input_queue)

    def consume_and_publish(self, visitor):

        logger.info(f"Consuming with callback {visitor.callback.__name__}")

        for message in self.consume():
            self.publish_response(message, visitor)

    def clear(self):
        self.channel.queue_purge(self._input_queue)
        self.channel.queue_purge(self._output_queue)

    @property
    def input_queue(self) -> QueueHandle:
        return monkey_patch_queue_handle(self.channel, self._input_queue)

    @property
    def output_queue(self) -> QueueHandle:
        return monkey_patch_queue_handle(self.channel, self._output_queue)