import asyncio
import json
import time
from collections.abc import Mapping
from datetime import datetime, timedelta
from enum import IntEnum, unique
from functools import singledispatch
from logging import getLogger
from pprint import pformat
from typing import (
Any, AsyncContextManager, Callable, Dict, Iterable, Optional, Union,
)
from warnings import warn
import aiormq
from aiormq.types import DeliveredMessage
from .exceptions import MessageProcessError
log = getLogger(__name__)
NoneType = type(None)
[docs]@unique
class DeliveryMode(IntEnum):
NOT_PERSISTENT = 1
PERSISTENT = 2
DateType = Union[int, datetime, float, timedelta, None]
MILLISECONDS = 1000
def to_milliseconds(seconds):
return int(seconds * MILLISECONDS)
@singledispatch
def encode_expiration(value) -> Optional[str]:
raise ValueError("Invalid timestamp type: %r" % type(value), value)
@encode_expiration.register(datetime)
def _(value):
now = datetime.now()
return str(to_milliseconds((value - now).total_seconds()))
@encode_expiration.register(int)
@encode_expiration.register(float)
def _(value):
return str(to_milliseconds(value))
@encode_expiration.register(timedelta)
def _(value):
return str(int(value.total_seconds() * 1000))
@encode_expiration.register(type(None))
def _(_):
return None
ZERO_TIME = datetime.utcfromtimestamp(0)
@singledispatch
def decode_expiration(t) -> Optional[float]:
raise ValueError("Invalid expiration type: %r" % type(t), t)
@decode_expiration.register(time.struct_time)
def _(t: time.struct_time) -> float:
return (datetime(*t[:7]) - ZERO_TIME).total_seconds()
@decode_expiration.register(str)
def _(t: str) -> float:
return float(t)
@singledispatch
def encode_timestamp(value) -> Optional[time.struct_time]:
raise ValueError("Invalid timestamp type: %r" % type(value), value)
@encode_timestamp.register(time.struct_time)
def _(value):
return value
@encode_timestamp.register(datetime)
def _(value):
return value.timetuple()
@encode_timestamp.register(float)
@encode_timestamp.register(int)
def _(value):
return datetime.utcfromtimestamp(value).timetuple()
@encode_timestamp.register(timedelta)
def _(value):
return datetime.utcnow() + value
@encode_timestamp.register(type(None))
def _(_):
return None
@singledispatch
def decode_timestamp(value) -> Optional[datetime]:
raise ValueError("Invalid timestamp type: %r" % type(value), value)
@decode_timestamp.register(datetime)
def _(value):
return value
@decode_timestamp.register(float)
@decode_timestamp.register(int)
def _(value):
return datetime.utcfromtimestamp(value)
@decode_timestamp.register(time.struct_time)
def _(value: time.struct_time):
return datetime(*value[:6])
@decode_timestamp.register(type(None))
def _(_):
return None
def optional(value, func: Callable[[Any], Any] = str, default=None):
return func(value) if value else default
class HeaderProxy(Mapping):
def __init__(self, headers: Dict[str, bytes]):
self._headers = headers # type: Dict[str, bytes]
self._cache = {} # type: Dict[str, Any]
def __getitem__(self, k):
if k not in self._headers:
raise KeyError(k)
if k not in self._cache:
value = self._headers[k]
if isinstance(value, bytes):
self._cache[k] = value.decode()
else:
self._cache[k] = value
return self._cache[k]
def __setitem__(self, key, value):
self._headers[key] = header_converter(value)
self._cache.pop(key, None)
def __len__(self) -> int:
return len(self._headers)
def __iter__(self):
for key in self._headers:
yield key
@singledispatch
def header_converter(value: Any) -> bytes:
return json.dumps(
value, separators=(",", ":"), ensure_ascii=False, default=repr,
).encode()
@header_converter.register(bytes)
@header_converter.register(datetime)
@header_converter.register(NoneType)
@header_converter.register(list)
@header_converter.register(int)
def _(v: bytes):
return v
@header_converter.register(bytearray)
def _(v: bytes):
return bytes(v)
@header_converter.register(str)
def _(v):
return v.encode()
@header_converter.register(set)
@header_converter.register(tuple)
@header_converter.register(frozenset)
def _(v: Iterable):
return header_converter(list(v))
def format_headers(d: Dict[str, Any]) -> Dict[str, bytes]:
ret = {}
if not d:
return ret
for key, value in d.items():
ret[key] = header_converter(value)
return ret
[docs]class Message:
""" AMQP message abstraction """
__slots__ = (
"app_id",
"body",
"body_size",
"content_encoding",
"content_type",
"correlation_id",
"delivery_mode",
"expiration",
"_headers",
"headers_raw",
"message_id",
"priority",
"reply_to",
"timestamp",
"type",
"user_id",
"__lock",
)
def __init__(
self,
body: bytes,
*,
headers: dict = None,
content_type: str = None,
content_encoding: str = None,
delivery_mode: DeliveryMode = None,
priority: int = None,
correlation_id=None,
reply_to: str = None,
expiration: DateType = None,
message_id: str = None,
timestamp: DateType = None,
type: str = None,
user_id: str = None,
app_id: str = None
):
""" Creates a new instance of Message
:param body: message body
:param headers: message headers
:param headers_raw: message raw headers
:param content_type: content type
:param content_encoding: content encoding
:param delivery_mode: delivery mode
:param priority: priority
:param correlation_id: correlation id
:param reply_to: reply to
:param expiration: expiration in seconds (or datetime or timedelta)
:param message_id: message id
:param timestamp: timestamp
:param type: type
:param user_id: user id
:param app_id: app id
"""
self.__lock = False
self.body = body if isinstance(body, bytes) else bytes(body)
self.body_size = len(self.body) if self.body else 0
self.headers_raw = format_headers(headers)
self._headers = HeaderProxy(self.headers_raw)
self.content_type = content_type
self.content_encoding = content_encoding
self.delivery_mode = DeliveryMode(
optional(
delivery_mode, func=int, default=DeliveryMode.NOT_PERSISTENT,
),
).value
self.priority = optional(priority, int, 0)
self.correlation_id = optional(correlation_id)
self.reply_to = optional(reply_to)
self.expiration = expiration
self.message_id = optional(message_id)
self.timestamp = encode_timestamp(timestamp)
self.type = optional(type)
self.user_id = optional(user_id)
self.app_id = optional(app_id)
@property
def headers(self):
return self._headers
@headers.setter
def headers(self, value: dict):
self.headers_raw = format_headers(value)
@staticmethod
def _as_bytes(value):
if isinstance(value, bytes):
return value
elif isinstance(value, str):
return value.encode()
elif isinstance(value, NoneType):
return b""
else:
return str(value).encode()
[docs] def info(self) -> dict:
""" Create a dict with message attributes
::
{
"body_size": 100,
"headers": {},
"content_type": "text/plain",
"content_encoding": "",
"delivery_mode": DeliveryMode.NOT_PERSISTENT,
"priority": 0,
"correlation_id": "",
"reply_to": "",
"expiration": "",
"message_id": "",
"timestamp": "",
"type": "",
"user_id": "",
"app_id": "",
}
"""
return {
"body_size": self.body_size,
"headers": self.headers_raw,
"content_type": self.content_type,
"content_encoding": self.content_encoding,
"delivery_mode": self.delivery_mode,
"priority": self.priority,
"correlation_id": self.correlation_id,
"reply_to": self.reply_to,
"expiration": self.expiration,
"message_id": self.message_id,
"timestamp": decode_timestamp(self.timestamp),
"type": str(self.type),
"user_id": self.user_id,
"app_id": self.app_id,
}
@property
def locked(self) -> bool:
""" is message locked
:return: :class:`bool`
"""
return bool(self.__lock)
@property
def properties(self) -> aiormq.spec.Basic.Properties:
""" Build :class:`aiormq.spec.Basic.Properties` object """
return aiormq.spec.Basic.Properties(
content_type=self.content_type,
content_encoding=self.content_encoding,
headers=self.headers_raw,
delivery_mode=self.delivery_mode,
priority=self.priority,
correlation_id=self.correlation_id,
reply_to=self.reply_to,
expiration=encode_expiration(self.expiration),
message_id=self.message_id,
timestamp=self.timestamp,
message_type=self.type,
user_id=self.user_id,
app_id=self.app_id,
)
def __repr__(self):
return "{name}:{repr}".format(
name=self.__class__.__name__, repr=pformat(self.info()),
)
def __setattr__(self, key, value):
if not key.startswith("_") and self.locked:
raise ValueError("Message is locked")
return super().__setattr__(key, value)
def __iter__(self):
return iter(self.body)
[docs] def lock(self):
""" Set lock flag to `True`"""
self.__lock = True
def __copy__(self):
return Message(
body=self.body,
headers=self.headers._headers,
content_encoding=self.content_encoding,
content_type=self.content_type,
delivery_mode=self.delivery_mode,
priority=self.priority,
correlation_id=self.correlation_id,
reply_to=self.reply_to,
expiration=self.expiration,
message_id=self.message_id,
timestamp=self.timestamp,
type=self.type,
user_id=self.user_id,
app_id=self.app_id,
)
[docs]class IncomingMessage(Message):
""" Incoming message is seems like Message but has additional methods for
message acknowledgement.
Depending on the acknowledgement mode used, RabbitMQ can consider a
message to be successfully delivered either immediately after it is sent
out (written to a TCP socket) or when an explicit ("manual") client
acknowledgement is received. Manually sent acknowledgements can be
positive or negative and use one of the following protocol methods:
* basic.ack is used for positive acknowledgements
* basic.nack is used for negative acknowledgements (note: this is a RabbitMQ
extension to AMQP 0-9-1)
* basic.reject is used for negative acknowledgements but has one limitations
compared to basic.nack
Positive acknowledgements simply instruct RabbitMQ to record a message as
delivered. Negative acknowledgements with basic.reject have the same effect.
The difference is primarily in the semantics: positive acknowledgements
assume a message was successfully processed while their negative
counterpart suggests that a delivery wasn't processed but still should
be deleted.
"""
__slots__ = (
"_loop",
"__channel",
"cluster_id",
"consumer_tag",
"delivery_tag",
"exchange",
"routing_key",
"redelivered",
"__no_ack",
"__processed",
"message_count",
)
def __init__(self, message: DeliveredMessage, no_ack: bool = False):
""" Create an instance of :class:`IncomingMessage` """
self.__channel = message.channel
self.__no_ack = no_ack
self.__processed = False
expiration = None
if message.header.properties.expiration:
expiration = decode_expiration(
message.header.properties.expiration,
)
super().__init__(
body=message.body,
content_type=message.header.properties.content_type,
content_encoding=message.header.properties.content_encoding,
headers=message.header.properties.headers,
delivery_mode=message.header.properties.delivery_mode,
priority=message.header.properties.priority,
correlation_id=message.header.properties.correlation_id,
reply_to=message.header.properties.reply_to,
expiration=expiration / 1000.0 if expiration else None,
message_id=message.header.properties.message_id,
timestamp=decode_timestamp(message.header.properties.timestamp),
type=message.header.properties.message_type,
user_id=message.header.properties.user_id,
app_id=message.header.properties.app_id,
)
self.cluster_id = message.header.properties.cluster_id
self.consumer_tag = None
self.delivery_tag = None
self.redelivered = None
self.message_count = None
if isinstance(message.delivery, aiormq.spec.Basic.GetOk):
self.message_count = message.delivery.message_count
self.delivery_tag = message.delivery.delivery_tag
self.redelivered = message.delivery.redelivered
elif isinstance(message.delivery, aiormq.spec.Basic.Deliver):
self.consumer_tag = message.delivery.consumer_tag
self.delivery_tag = message.delivery.delivery_tag
self.redelivered = message.delivery.redelivered
self.routing_key = message.delivery.routing_key
self.exchange = message.delivery.exchange
if no_ack or not self.delivery_tag:
self.lock()
self.__processed = True
@property
def channel(self):
return self.__channel
[docs] def process(
self,
requeue=False,
reject_on_redelivered=False,
ignore_processed=False,
) -> AsyncContextManager:
""" Context manager for processing the message
>>> async def on_message_received(message: IncomingMessage):
... async with message.process():
... # When exception will be raised
... # the message will be rejected
... print(message.body)
Example with ignore_processed=True
>>> async def on_message_received(message: IncomingMessage):
... async with message.process(ignore_processed=True):
... # Now (with ignore_processed=True) you may reject
... # (or ack) message manually too
... if True: # some reasonable condition here
... await message.reject()
... print(message.body)
:param requeue: Requeue message when exception.
:param reject_on_redelivered:
When True message will be rejected only when
message was redelivered.
:param ignore_processed: Do nothing if message already processed
"""
return ProcessContext(
self,
requeue=requeue,
reject_on_redelivered=reject_on_redelivered,
ignore_processed=ignore_processed,
)
[docs] def ack(self, multiple: bool = False) -> asyncio.Task:
""" Send basic.ack is used for positive acknowledgements
.. note::
This method looks like a blocking-method, but actually it just
sends bytes to the socket and doesn't require any responses from
the broker.
:param multiple: If set to True, the message's delivery tag is
treated as "up to and including", so that multiple
messages can be acknowledged with a single method.
If set to False, the ack refers to a single message.
:return: None
"""
if self.__no_ack:
raise TypeError('Can\'t ack message with "no_ack" flag')
if self.__processed:
raise MessageProcessError("Message already processed")
task = asyncio.ensure_future(
self.__channel.basic_ack(
delivery_tag=self.delivery_tag, multiple=multiple,
),
)
self.__processed = True
if not self.locked:
self.lock()
return task
[docs] def reject(self, requeue: bool = False) -> asyncio.Task:
""" When `requeue=True` the message will be returned to queue.
Otherwise message will be dropped.
.. note::
This method looks like a blocking-method, but actually it just
sends bytes to the socket and doesn't require any responses from
the broker.
:param requeue: bool
"""
if self.__no_ack:
raise TypeError('This message has "no_ack" flag.')
if self.__processed:
raise MessageProcessError("Message already processed")
task = asyncio.ensure_future(
self.__channel.basic_reject(
delivery_tag=self.delivery_tag, requeue=requeue,
),
)
self.__processed = True
if not self.locked:
self.lock()
return task
def nack(
self, multiple: bool = False, requeue: bool = True,
) -> asyncio.Task:
if not self.__channel.connection.basic_nack:
raise RuntimeError("Method not supported on server")
if self.__no_ack:
raise TypeError('Can\'t nack message with "no_ack" flag')
if self.__processed:
raise MessageProcessError("Message already processed")
task = asyncio.ensure_future(
self.__channel.basic_nack(
delivery_tag=self.delivery_tag,
multiple=multiple,
requeue=requeue,
),
)
self.__processed = True
if not self.locked:
self.lock()
return task
[docs] def info(self) -> dict:
""" Method returns dict representation of the message """
info = super(IncomingMessage, self).info()
info["cluster_id"] = self.cluster_id
info["consumer_tag"] = self.consumer_tag
info["delivery_tag"] = self.delivery_tag
info["exchange"] = self.exchange
info["redelivered"] = self.redelivered
info["routing_key"] = self.routing_key
return info
@property
def processed(self):
return self.__processed
class ReturnedMessage(IncomingMessage):
pass
class ProcessContext(AsyncContextManager):
def __init__(
self,
message: IncomingMessage,
*,
requeue,
reject_on_redelivered,
ignore_processed
):
self.message = message
self.requeue = requeue
self.reject_on_redelivered = reject_on_redelivered
self.ignore_processed = ignore_processed
async def __aenter__(self):
return self.message
async def __aexit__(self, exc_type, exc_val, exc_tb):
if not exc_type:
if not self.ignore_processed or not self.message.processed:
await self.message.ack()
return
if not self.ignore_processed or not self.message.processed:
if self.reject_on_redelivered and self.message.redelivered:
if not self.message.channel.is_closed:
log.info(
"Message %r was redelivered and will be rejected",
self.message,
)
await self.message.reject(requeue=False)
return
log.warning(
"Message %r was redelivered and reject is not sent "
"since channel is closed",
self.message,
)
else:
if not self.message.channel.is_closed:
await self.message.reject(requeue=self.requeue)
return
log.warning("Reject is not sent since channel is closed")
def __enter__(self):
warn('Use "async with message.process()" instead', DeprecationWarning)
return self.message
def __exit__(self, exc_type, exc_val, exc_tb):
if not exc_type:
if not self.ignore_processed or not self.message.processed:
self.message.ack()
return
if not self.ignore_processed or not self.message.processed:
if self.reject_on_redelivered and self.message.redelivered:
if not self.message.channel.is_closed:
log.info(
"Message %r was redelivered and will be rejected",
self.message,
)
self.message.reject(requeue=False)
return
log.warning(
"Message %r was redelivered and reject is not sent "
"since channel is closed",
self.message,
)
else:
if not self.message.channel.is_closed:
self.message.reject(requeue=self.requeue)
return
log.warning("Reject is not sent since channel is closed")
__all__ = "Message", "IncomingMessage", "ReturnedMessage", "DeliveryMode"
