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 aiormq.tools import awaitable
from aio_pika.abc import (
AbstractChannel, AbstractExchange, AbstractIncomingMessage, AbstractQueue,
ConsumerTag, DeliveryMode,
)
from aio_pika.message import Message, ReturnedMessage
from ..tools import create_task
from .base import Base, Proxy
log = logging.getLogger(__name__)
T = TypeVar("T")
class MessageProcessingError(Exception):
pass
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:
`worker.py` ::
master = Master(channel)
worker = await master.create_worker('test_worker', lambda x: print(x))
`master.py` ::
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`
"""
self.channel: AbstractChannel = channel
self.loop: asyncio.AbstractEventLoop = asyncio.get_event_loop()
self.proxy = Proxy(self.create_task)
self.channel.return_callbacks.add(self.on_message_returned)
self._requeue = requeue
self._reject_on_redelivered = reject_on_redelivered
@property
def exchange(self) -> AbstractExchange:
return self.channel.default_exchange
@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 self.channel.declare_queue(channel_name, **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[aiormq.abc.ConfirmationFrameType]:
""" 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 self.exchange.publish(
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))