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"""
kombu.transport.base
====================
Base transport interface.
:copyright: (c) 2009 - 2010 by Ask Solem.
:license: BSD, see LICENSE for more details.
"""
from kombu import serialization
from kombu.compression import decompress
from kombu.exceptions import MessageStateError
ACKNOWLEDGED_STATES = frozenset(["ACK", "REJECTED", "REQUEUED"])
class Message(object):
"""Base class for received messages."""
_state = None
MessageStateError = MessageStateError
#: The channel the message was received on.
channel = None
#: Delivery tag used to identify the message in this channel.
delivery_tag = None
#: Content type used to identify the type of content.
content_type = None
#: Content encoding used to identify the text encoding of the body.
content_encoding = None
#: Additional delivery information.
delivery_info = None
#: Message headers
headers = None
#: Application properties
properties = None
#: Raw message body (may be serialized), see :attr:`payload` instead.
body = None
def __init__(self, channel, body=None, delivery_tag=None,
content_type=None, content_encoding=None, delivery_info={},
properties=None, headers=None, postencode=None,
**kwargs):
self.channel = channel
self.body = body
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"
compression = self.headers.get("compression")
if compression:
self.body = decompress(self.body, compression)
if postencode and isinstance(self.body, unicode):
self.body = self.body.encode(postencode)
def ack(self):
"""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.acknowledged:
raise self.MessageStateError(
"Message already acknowledged with state: %s" % self._state)
self.channel.basic_ack(self.delivery_tag)
self._state = "ACK"
def reject(self):
"""Reject this message.
The message will be discarded by the server.
:raises MessageStateError: If the message has already been
acknowledged/requeued/rejected.
"""
if self.acknowledged:
raise self.MessageStateError(
"Message already acknowledged with state: %s" % self._state)
self.channel.basic_reject(self.delivery_tag, requeue=False)
self._state = "REJECTED"
def requeue(self):
"""Reject this message and put it back on the queue.
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.acknowledged:
raise self.MessageStateError(
"Message already acknowledged with state: %s" % self._state)
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."""
return serialization.decode(self.body, self.content_type,
self.content_encoding)
@property
def acknowledged(self):
"""Set to true if the message has been acknowledged."""
return self._state in ACKNOWLEDGED_STATES
@property
def payload(self):
"""The decoded message body."""
if not self._decoded_cache:
self._decoded_cache = self.decode()
return self._decoded_cache
class Transport(object):
"""Base class for transports."""
#: The :class:`~kombu.connection.BrokerConnection` owning this instance.
client = None
#: Default port used when no port has been specified.
default_port = None
#: Tuple of errors that can happen due to connection failure.
connection_errors = ()
#: Tuple of errors that can happen due to channel/method failure.
channel_errors = ()
def __init__(self, client, **kwargs):
self.client = client
def establish_connection(self):
raise NotImplementedError("Subclass responsibility")
def close_connection(self, connection):
raise NotImplementedError("Subclass responsibility")
def create_channel(self, connection):
raise NotImplementedError("Subclass responsibility")
def close_channel(self, connection):
raise NotImplementedError("Subclass responsibility")
def drain_events(self, connection, **kwargs):
raise NotImplementedError("Subclass responsibility")
|
