Source code for aio_pika.patterns.master

import asyncio
import gzip
import json
import logging
from functools import partial
from types import MappingProxyType
from typing import Any, Awaitable, Callable, Mapping, Optional, TypeVar

import aiormq
from import awaitable

from import (
    AbstractChannel, AbstractExchange, AbstractIncomingMessage, AbstractQueue,
    ConsumerTag, DeliveryMode,
from aio_pika.message import Message, ReturnedMessage

from import create_task
from .base import Base, Proxy

log = logging.getLogger(__name__)
T = TypeVar("T")

class MessageProcessingError(Exception):

class NackMessage(MessageProcessingError):
    def __init__(self, requeue: bool = False):
        self.requeue = requeue

class RejectMessage(MessageProcessingError):
    def __init__(self, requeue: bool = False):
        self.requeue = requeue

[docs]class Worker: __slots__ = ( "queue", "consumer_tag", "loop", ) def __init__( self, queue: AbstractQueue, consumer_tag: ConsumerTag, loop: asyncio.AbstractEventLoop, ): self.queue = queue self.consumer_tag = consumer_tag self.loop = loop
[docs] def close(self) -> Awaitable[None]: """ Cancel subscription to the channel :return: :class:`asyncio.Task` """ async def closer() -> None: await self.queue.cancel(self.consumer_tag) return create_task(closer)
[docs]class Master(Base): __slots__ = ( "channel", "loop", "proxy", ) DELIVERY_MODE = DeliveryMode.PERSISTENT __doc__ = """ Implements Master/Worker pattern. Usage example: `` :: master = Master(channel) worker = await master.create_worker('test_worker', lambda x: print(x)) `` :: master = Master(channel) await master.proxy.test_worker('foo') """ def __init__( self, channel: AbstractChannel, requeue: bool = True, reject_on_redelivered: bool = False, ): """ Creates a new :class:`Master` instance. :param channel: Initialized instance of :class:`aio_pika.Channel` """ AbstractChannel = channel self.loop: asyncio.AbstractEventLoop = asyncio.get_event_loop() self.proxy = Proxy(self.create_task) self._requeue = requeue self._reject_on_redelivered = reject_on_redelivered @property def exchange(self) -> AbstractExchange: return @staticmethod def on_message_returned( channel: AbstractChannel, message: ReturnedMessage, ) -> None: log.warning( "Message returned. Probably destination queue does not exists: %r", message, )
[docs] def serialize(self, data: Any) -> bytes: """ Serialize data to the bytes. Uses `pickle` by default. You should overlap this method when you want to change serializer :param data: Data which will be serialized :returns: bytes """ return super().serialize(data)
[docs] def deserialize(self, data: bytes) -> Any: """ Deserialize data from bytes. Uses `pickle` by default. You should overlap this method when you want to change serializer :param data: Data which will be deserialized :returns: :class:`Any` """ return super().deserialize(data)
@classmethod async def execute( cls, func: Callable[..., Awaitable[T]], kwargs: Any, ) -> T: kwargs = kwargs or {} if not isinstance(kwargs, dict): raise RejectMessage(requeue=False) return await func(**kwargs) async def on_message( self, func: Callable[..., Any], message: AbstractIncomingMessage, ) -> None: async with message.process( requeue=self._requeue, reject_on_redelivered=self._reject_on_redelivered, ignore_processed=True, ): try: await self.execute(func, self.deserialize(message.body)) except RejectMessage as e: await message.reject(requeue=e.requeue) except NackMessage as e: await message.nack(requeue=e.requeue) async def create_queue( self, channel_name: str, **kwargs: Any ) -> AbstractQueue: return await, **kwargs)
[docs] async def create_worker( self, channel_name: str, func: Callable[..., Any], **kwargs: Any ) -> Worker: """ Creates a new :class:`Worker` instance. """ queue = await self.create_queue(channel_name, **kwargs) if hasattr(func, "_is_coroutine"): fn = func else: fn = awaitable(func) consumer_tag = await queue.consume(partial(self.on_message, fn)) return Worker(queue, consumer_tag, self.loop)
[docs] async def create_task( self, channel_name: str, kwargs: Mapping[str, Any] = MappingProxyType({}), **message_kwargs: Any ) -> Optional[]: """ Creates a new task for the worker """ message = Message( body=self.serialize(kwargs), content_type=self.CONTENT_TYPE, delivery_mode=self.DELIVERY_MODE, **message_kwargs ) return await message, channel_name, mandatory=True, )
class JsonMaster(Master): SERIALIZER = json CONTENT_TYPE = "application/json" def serialize(self, data: Any) -> bytes: return self.SERIALIZER.dumps(data, ensure_ascii=False).encode() class CompressedJsonMaster(Master): SERIALIZER = json CONTENT_TYPE = "application/json;compression=gzip" COMPRESS_LEVEL = 6 def serialize(self, data: Any) -> bytes: return gzip.compress( self.SERIALIZER.dumps(data, ensure_ascii=False).encode(), compresslevel=self.COMPRESS_LEVEL, ) def deserialize(self, data: bytes) -> Any: return self.SERIALIZER.loads(gzip.decompress(data))