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"""Message class."""
from __future__ import annotations
import sys
from .compression import decompress
from .exceptions import MessageStateError, reraise
from .serialization import loads
from .utils.functional import dictfilter
__all__ = ('Message',)
ACK_STATES = {'ACK', 'REJECTED', 'REQUEUED'}
IS_PYPY = hasattr(sys, 'pypy_version_info')
class Message:
"""Base class for received messages.
Keyword Arguments:
-----------------
channel (ChannelT): If message was received, this should be the
channel that the message was received on.
body (str): Message body.
delivery_mode (bool): Set custom delivery mode.
Defaults to :attr:`delivery_mode`.
priority (int): Message priority, 0 to broker configured
max priority, where higher is better.
content_type (str): The messages content_type. If content_type
is set, no serialization occurs as it is assumed this is either
a binary object, or you've done your own serialization.
Leave blank if using built-in serialization as our library
properly sets content_type.
content_encoding (str): The character set in which this object
is encoded. Use "binary" if sending in raw binary objects.
Leave blank if using built-in serialization as our library
properly sets content_encoding.
properties (Dict): Message properties.
headers (Dict): Message headers.
"""
MessageStateError = MessageStateError
errors = None
if not IS_PYPY: # pragma: no cover
__slots__ = (
'_state', 'channel', 'delivery_tag',
'content_type', 'content_encoding',
'delivery_info', 'headers', 'properties',
'body', '_decoded_cache', 'accept', '__dict__',
)
def __init__(self, body=None, delivery_tag=None,
content_type=None, content_encoding=None, delivery_info=None,
properties=None, headers=None, postencode=None,
accept=None, channel=None, **kwargs):
delivery_info = {} if not delivery_info else delivery_info
self.errors = [] if self.errors is None else self.errors
self.channel = channel
self.delivery_tag = delivery_tag
self.content_type = content_type
self.content_encoding = content_encoding
self.delivery_info = delivery_info
self.headers = headers or {}
self.properties = properties or {}
self._decoded_cache = None
self._state = 'RECEIVED'
self.accept = accept
compression = self.headers.get('compression')
if not self.errors and compression:
try:
body = decompress(body, compression)
except Exception:
self.errors.append(sys.exc_info())
if not self.errors and postencode and isinstance(body, str):
try:
body = body.encode(postencode)
except Exception:
self.errors.append(sys.exc_info())
self.body = body
def _reraise_error(self, callback=None):
try:
reraise(*self.errors[0])
except Exception as exc:
if not callback:
raise
callback(self, exc)
def ack(self, multiple=False):
"""Acknowledge this message as being processed.
This will remove the message from the queue.
Raises
------
MessageStateError: If the message has already been
acknowledged/requeued/rejected.
"""
if self.channel is None:
raise self.MessageStateError(
'This message does not have a receiving channel')
if self.channel.no_ack_consumers is not None:
try:
consumer_tag = self.delivery_info['consumer_tag']
except KeyError:
pass
else:
if consumer_tag in self.channel.no_ack_consumers:
return
if self.acknowledged:
raise self.MessageStateError(
'Message already acknowledged with state: {0._state}'.format(
self))
self.channel.basic_ack(self.delivery_tag, multiple=multiple)
self._state = 'ACK'
def ack_log_error(self, logger, errors, multiple=False):
try:
self.ack(multiple=multiple)
except BrokenPipeError as exc:
logger.critical("Couldn't ack %r, reason:%r",
self.delivery_tag, exc, exc_info=True)
raise
except errors as exc:
logger.critical("Couldn't ack %r, reason:%r",
self.delivery_tag, exc, exc_info=True)
def reject_log_error(self, logger, errors, requeue=False):
try:
self.reject(requeue=requeue)
except errors as exc:
logger.critical("Couldn't reject %r, reason: %r",
self.delivery_tag, exc, exc_info=True)
def reject(self, requeue=False):
"""Reject this message.
The message will be discarded by the server.
Raises
------
MessageStateError: If the message has already been
acknowledged/requeued/rejected.
"""
if self.channel is None:
raise self.MessageStateError(
'This message does not have a receiving channel')
if self.acknowledged:
raise self.MessageStateError(
'Message already acknowledged with state: {0._state}'.format(
self))
self.channel.basic_reject(self.delivery_tag, requeue=requeue)
self._state = 'REJECTED'
def requeue(self):
"""Reject this message and put it back on the queue.
Warning:
-------
You must not use this method as a means of selecting messages
to process.
Raises
------
MessageStateError: If the message has already been
acknowledged/requeued/rejected.
"""
if self.channel is None:
raise self.MessageStateError(
'This message does not have a receiving channel')
if self.acknowledged:
raise self.MessageStateError(
'Message already acknowledged with state: {0._state}'.format(
self))
self.channel.basic_reject(self.delivery_tag, requeue=True)
self._state = 'REQUEUED'
def decode(self):
"""Deserialize the message body.
Returning the original python structure sent by the publisher.
Note:
----
The return value is memoized, use `_decode` to force
re-evaluation.
"""
if not self._decoded_cache:
self._decoded_cache = self._decode()
return self._decoded_cache
def _decode(self):
return loads(self.body, self.content_type,
self.content_encoding, accept=self.accept)
@property
def acknowledged(self):
"""Set to true if the message has been acknowledged."""
return self._state in ACK_STATES
@property
def payload(self):
"""The decoded message body."""
return self._decoded_cache if self._decoded_cache else self.decode()
def __repr__(self):
return '<{} object at {:#x} with details {!r}>'.format(
type(self).__name__, id(self), dictfilter(
state=self._state,
content_type=self.content_type,
delivery_tag=self.delivery_tag,
body_length=len(self.body) if self.body is not None else None,
properties=dictfilter(
correlation_id=self.properties.get('correlation_id'),
type=self.properties.get('type'),
),
delivery_info=dictfilter(
exchange=self.delivery_info.get('exchange'),
routing_key=self.delivery_info.get('routing_key'),
),
),
)
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