taskiq-aio-pika

AioPika broker for taskiq

This lirary provides you with aio-pika broker for taskiq.

Usage:

from taskiq_aio_pika import AioPikaBroker

broker = AioPikaBroker()

@broker.task
async def test() -> None:
    print("nothing")

Non-obvious things

You can send delayed messages and set priorities to messages using labels.

Delays

Default retries

To send delayed message, you have to specify delay label. You can do it with task decorator, or by using kicker. In this type of delay we are using additional queue with expiration parameter and after with time message will be deleted from delay queue and sent to the main taskiq queue. For example:

broker = AioPikaBroker()

@broker.task(delay=3)
async def delayed_task() -> int:
    return 1

async def main():
    await broker.startup()
    # This message will be received by workers
    # After 3 seconds delay.
    await delayed_task.kiq()

    # This message is going to be received after the delay in 4 seconds.
    # Since we overriden the `delay` label using kicker.
    await delayed_task.kicker().with_labels(delay=4).kiq()

    # This message is going to be send immediately. Since we deleted the label.
    await delayed_task.kicker().with_labels(delay=None).kiq()

    # Of course the delay is managed by rabbitmq, so you don't
    # have to wait delay period before message is going to be sent.

Retries with rabbitmq-delayed-message-exchange plugin

To send delayed message you can install rabbitmq-delayed-message-exchange plugin https://github.com/rabbitmq/rabbitmq-delayed-message-exchange.

And you need to configure you broker. There is delayed_message_exchange_plugin AioPikaBroker parameter and it must be True to turn on delayed message functionality.

The delay plugin can handle tasks with different delay times well, and the delay based on dead letter queue is suitable for tasks with the same delay time. For example:

broker = AioPikaBroker(
    delayed_message_exchange_plugin=True,
)

@broker.task(delay=3)
async def delayed_task() -> int:
    return 1

async def main():
    await broker.startup()
    # This message will be received by workers
    # After 3 seconds delay.
    await delayed_task.kiq()

    # This message is going to be received after the delay in 4 seconds.
    # Since we overriden the `delay` label using kicker.
    await delayed_task.kicker().with_labels(delay=4).kiq()

Priorities

You can define priorities for messages using priority label. Messages with higher priorities are delivered faster. But to use priorities you need to define max_priority of the main queue, by passing max_priority parameter in broker's init. This parameter sets maximum priority for the queue and declares it as the prority queue.

Before doing so please read the documentation about what downsides you get by using prioritized queues.

broker = AioPikaBroker(max_priority=10)

# We can define default priority for tasks.
@broker.task(priority=2)
async def prio_task() -> int:
    return 1

async def main():
    await broker.startup()
    # This message has priority = 2.
    await prio_task.kiq()

    # This message is going to have priority 4.
    await prio_task.kicker().with_labels(priority=4).kiq()

    # This message is going to have priority 0.
    await prio_task.kicker().with_labels(priority=None).kiq()

Configuration

AioPikaBroker parameters:

• url - url to rabbitmq. If None, "amqp://guest:guest@localhost:5672" is used.
• result_backend - custom result backend.
• task_id_generator - custom task_id genertaor.
• exchange_name - name of exchange that used to send messages.
• exchange_type - type of the exchange. Used only if declare_exchange is True.
• queue_name - queue that used to get incoming messages.
• routing_key - that used to bind that queue to the exchange.
• declare_exchange - whether you want to declare new exchange if it doesn't exist.
• max_priority - maximum priority for messages.
• delay_queue_name - custom delay queue name. This queue is used to deliver messages with delays.
• dead_letter_queue_name - custom dead letter queue name. This queue is used to receive negatively acknowleged messages from the main queue.
• qos - number of messages that worker can prefetch.
• declare_queues - whether you want to declare queues even on client side. May be useful for message persistance.