import asyncio
import json
import logging
import time
import uuid
from enum import Enum
from functools import partial
from typing import Any, Callable, Dict, Optional, Tuple
from aiormq.abc import ExceptionType
from aio_pika.abc import (
AbstractChannel, AbstractExchange, AbstractIncomingMessage, AbstractQueue,
ConsumerTag, DeliveryMode,
)
from aio_pika.exceptions import MessageProcessError
from aio_pika.exchange import ExchangeType
from aio_pika.message import IncomingMessage, Message
from ..tools import ensure_awaitable
from .base import Base, CallbackType, Proxy, T
log = logging.getLogger(__name__)
class RPCException(RuntimeError):
pass
class RPCMessageType(str, Enum):
ERROR = "error"
RESULT = "result"
CALL = "call"
# This needed only for migration from 6.x to 7.x
# TODO: Remove this in 8.x release
RPCMessageTypes = RPCMessageType # noqa
[docs]class RPC(Base):
__slots__ = (
"channel",
"loop",
"proxy",
"futures",
"result_queue",
"result_consumer_tag",
"routes",
"queues",
"consumer_tags",
"dlx_exchange",
"rpc_exchange",
"host_exceptions",
)
DLX_NAME = "rpc.dlx"
DELIVERY_MODE = DeliveryMode.NOT_PERSISTENT
__doc__ = """
Remote Procedure Call helper.
Create an instance ::
rpc = await RPC.create(channel, host_exceptions=False)
Registering python function ::
# RPC instance passes only keyword arguments
def multiply(*, x, y):
return x * y
await rpc.register("multiply", multiply)
Call function through proxy ::
assert await rpc.proxy.multiply(x=2, y=3) == 6
Call function explicit ::
assert await rpc.call('multiply', dict(x=2, y=3)) == 6
Show exceptions on remote side ::
rpc = await RPC.create(channel, host_exceptions=True)
"""
result_queue: AbstractQueue
result_consumer_tag: ConsumerTag
dlx_exchange: AbstractExchange
rpc_exchange: Optional[AbstractExchange]
def __init__(
self, channel: AbstractChannel,
host_exceptions: bool = False,
) -> None:
self.channel = channel
self.loop = asyncio.get_event_loop()
self.proxy = Proxy(self.call)
self.futures: Dict[str, asyncio.Future] = {}
self.routes: Dict[str, Callable[..., Any]] = {}
self.queues: Dict[Callable[..., Any], AbstractQueue] = {}
self.consumer_tags: Dict[Callable[..., Any], ConsumerTag] = {}
self.host_exceptions = host_exceptions
def __remove_future(
self, correlation_id: str,
) -> Callable[[asyncio.Future], None]:
def do_remove(future: asyncio.Future) -> None:
log.debug("Remove done future %r", future)
self.futures.pop(correlation_id, None)
return do_remove
def create_future(self) -> Tuple[asyncio.Future, str]:
future = self.loop.create_future()
log.debug("Create future for RPC call")
correlation_id = str(uuid.uuid4())
self.futures[correlation_id] = future
future.add_done_callback(self.__remove_future(correlation_id))
return future, correlation_id
def _format_routing_key(self, method_name: str) -> str:
return (
f"{self.rpc_exchange.name}::{method_name}"
if self.rpc_exchange
else method_name
)
async def close(self) -> None:
if not hasattr(self, "result_queue"):
log.warning("RPC already closed")
return
log.debug("Cancelling listening %r", self.result_queue)
await self.result_queue.cancel(self.result_consumer_tag)
del self.result_consumer_tag
log.debug("Unbinding %r", self.result_queue)
await self.result_queue.unbind(
self.dlx_exchange, "",
arguments={"From": self.result_queue.name, "x-match": "any"},
)
log.debug("Cancelling undone futures %r", self.futures)
for future in self.futures.values():
if future.done():
continue
future.set_exception(asyncio.CancelledError)
log.debug("Deleting %r", self.result_queue)
await self.result_queue.delete()
del self.result_queue
del self.dlx_exchange
if self.rpc_exchange:
del self.rpc_exchange
async def initialize(
self, auto_delete: bool = True,
durable: bool = False, exchange: str = "", **kwargs: Any,
) -> None:
if hasattr(self, "result_queue"):
return
self.rpc_exchange = await self.channel.declare_exchange(
exchange,
type=ExchangeType.DIRECT,
auto_delete=True,
durable=durable,
) if exchange else None
self.result_queue = await self.channel.declare_queue(
None, auto_delete=auto_delete, durable=durable, **kwargs,
)
self.dlx_exchange = await self.channel.declare_exchange(
self.DLX_NAME, type=ExchangeType.HEADERS, auto_delete=True,
)
await self.result_queue.bind(
self.dlx_exchange,
"",
arguments={"From": self.result_queue.name, "x-match": "any"},
)
self.result_consumer_tag = await self.result_queue.consume(
self.on_result_message, exclusive=True, no_ack=True,
)
self.channel.close_callbacks.add(self.on_close)
self.channel.return_callbacks.add(self.on_message_returned)
def on_close(
self,
channel: Optional[AbstractChannel],
exc: Optional[ExceptionType] = None,
) -> None:
log.debug("Closing RPC futures because %r", exc)
for future in self.futures.values():
if future.done():
continue
future.set_exception(exc or Exception)
[docs] @classmethod
async def create(cls, channel: AbstractChannel, **kwargs: Any) -> "RPC":
""" Creates a new instance of :class:`aio_pika.patterns.RPC`.
You should use this method instead of :func:`__init__`,
because :func:`create` returns coroutine and makes async initialize
:param channel: initialized instance of :class:`aio_pika.Channel`
:returns: :class:`RPC`
"""
rpc = cls(channel)
await rpc.initialize(**kwargs)
return rpc
def on_message_returned(
self,
channel: Optional[AbstractChannel],
message: AbstractIncomingMessage,
) -> None:
if message.correlation_id is None:
log.warning(
"Message without correlation_id was returned: %r", message,
)
return
future = self.futures.pop(message.correlation_id, None)
if not future or future.done():
log.warning("Unknown message was returned: %r", message)
return
future.set_exception(
MessageProcessError("Message has been returned", message),
)
async def on_result_message(self, message: AbstractIncomingMessage) -> None:
if message.correlation_id is None:
log.warning(
"Message without correlation_id was received: %r", message,
)
return
future = self.futures.pop(message.correlation_id, None)
if future is None:
log.warning("Unknown message: %r", message)
return
try:
payload = await self.deserialize_message(message)
except Exception as e:
log.error("Failed to deserialize response on message: %r", message)
future.set_exception(e)
return
if message.type == RPCMessageType.RESULT.value:
future.set_result(payload)
elif message.type == RPCMessageType.ERROR.value:
if not isinstance(payload, Exception):
payload = RPCException("Wrapped non-exception object", payload)
future.set_exception(payload)
elif message.type == RPCMessageType.CALL.value:
future.set_exception(
asyncio.TimeoutError("Message timed-out", message),
)
else:
future.set_exception(
RuntimeError("Unknown message type %r" % message.type),
)
async def on_call_message(
self, method_name: str, message: IncomingMessage,
) -> None:
routing_key = self._format_routing_key(method_name)
if routing_key not in self.routes:
log.warning("Method %r not registered in %r", method_name, self)
return
try:
payload = await self.deserialize_message(message)
func = self.routes[routing_key]
result: Any = await self.execute(func, payload)
message_type = RPCMessageType.RESULT
except Exception as e:
result = self.serialize_exception(e)
message_type = RPCMessageType.ERROR
if self.host_exceptions is True:
log.exception(e)
if not message.reply_to:
log.info(
'RPC message without "reply_to" header %r call result '
"will be lost",
message,
)
await message.ack()
return
try:
result_message = await self.serialize_message(
payload=result,
message_type=message_type,
correlation_id=message.correlation_id,
delivery_mode=message.delivery_mode,
)
except asyncio.CancelledError:
raise
except Exception as e:
result_message = await self.serialize_message(
payload=e,
message_type=RPCMessageType.ERROR,
correlation_id=message.correlation_id,
delivery_mode=message.delivery_mode,
)
try:
await self.channel.default_exchange.publish(
result_message, message.reply_to, mandatory=False,
)
except Exception:
log.exception("Failed to send reply %r", result_message)
await message.reject(requeue=False)
return
if message_type == RPCMessageType.ERROR.value:
await message.ack()
return
await message.ack()
[docs] def serialize_exception(self, exception: Exception) -> Any:
""" Make python exception serializable """
return exception
[docs] async def execute(self, func: CallbackType, payload: Dict[str, Any]) -> T:
""" Executes rpc call. Might be overlapped. """
return await func(**payload)
async def deserialize_message(
self, message: AbstractIncomingMessage,
) -> Any:
return self.deserialize(message.body)
async def serialize_message(
self, payload: Any, message_type: RPCMessageType,
correlation_id: Optional[str], delivery_mode: DeliveryMode,
**kwargs: Any,
) -> Message:
return Message(
self.serialize(payload),
content_type=self.CONTENT_TYPE,
correlation_id=correlation_id,
delivery_mode=delivery_mode,
timestamp=time.time(),
type=message_type.value,
**kwargs,
)
[docs] async def call(
self,
method_name: str,
kwargs: Optional[Dict[str, Any]] = None,
*,
expiration: Optional[int] = None,
priority: int = 5,
delivery_mode: DeliveryMode = DELIVERY_MODE,
) -> Any:
""" Call remote method and awaiting result.
:param method_name: Name of method
:param kwargs: Methos kwargs
:param expiration:
If not `None` messages which staying in queue longer
will be returned and :class:`asyncio.TimeoutError` will be raised.
:param priority: Message priority
:param delivery_mode: Call message delivery mode
:raises asyncio.TimeoutError: when message expired
:raises CancelledError: when called :func:`RPC.cancel`
:raises RuntimeError: internal error
"""
future, correlation_id = self.create_future()
message = await self.serialize_message(
payload=kwargs or {},
message_type=RPCMessageType.CALL,
correlation_id=correlation_id,
delivery_mode=delivery_mode,
reply_to=self.result_queue.name,
headers={"From": self.result_queue.name},
priority=priority,
)
if expiration is not None:
message.expiration = expiration
routing_key = self._format_routing_key(method_name)
log.debug("Publishing calls for %s(%r)", routing_key, kwargs)
exchange = self.rpc_exchange or self.channel.default_exchange
await exchange.publish(
message, routing_key=routing_key,
mandatory=True,
)
log.debug("Waiting RPC result for %s(%r)", routing_key, kwargs)
return await future
[docs] async def register(
self, method_name: str, func: CallbackType, **kwargs: Any,
) -> Any:
""" Method creates a queue with name which equal of
`method_name` argument. Then subscribes this queue.
:param method_name: Method name
:param func:
target function. Function **MUST** accept only keyword arguments.
:param kwargs: arguments which will be passed to `queue_declare`
:raises RuntimeError:
Function already registered in this :class:`RPC` instance
or method_name already used.
"""
arguments = kwargs.pop("arguments", {})
arguments.update({"x-dead-letter-exchange": self.DLX_NAME})
func = ensure_awaitable(func)
kwargs["arguments"] = arguments
routing_key = self._format_routing_key(method_name)
queue = await self.channel.declare_queue(routing_key, **kwargs)
if self.rpc_exchange:
await queue.bind(
self.rpc_exchange,
routing_key,
)
if func in self.consumer_tags:
raise RuntimeError("Function already registered")
if routing_key in self.routes:
raise RuntimeError(
"Method name already used for %r" % self.routes[routing_key],
)
self.consumer_tags[func] = await queue.consume(
partial(self.on_call_message, method_name),
)
self.routes[routing_key] = func
self.queues[func] = queue
[docs] async def unregister(self, func: CallbackType) -> None:
""" Cancels subscription to the method-queue.
:param func: Function
"""
if func not in self.consumer_tags:
return
consumer_tag = self.consumer_tags.pop(func)
queue = self.queues.pop(func)
await queue.cancel(consumer_tag)
self.routes.pop(queue.name)
class JsonRPCError(RuntimeError):
pass
class JsonRPC(RPC):
SERIALIZER = json
CONTENT_TYPE = "application/json"
def serialize(self, data: Any) -> bytes:
return self.SERIALIZER.dumps(
data, ensure_ascii=False, default=repr,
).encode()
def serialize_exception(self, exception: Exception) -> Any:
return {
"error": {
"type": exception.__class__.__name__,
"message": repr(exception),
"args": exception.args,
},
}
async def deserialize_message(
self, message: AbstractIncomingMessage,
) -> Any:
payload = await super().deserialize_message(message)
if message.type == RPCMessageType.ERROR:
payload = JsonRPCError("RPC exception", payload)
return payload
__all__ = (
"JsonRPC",
"RPC",
"RPCException",
"RPCMessageType",
)