nova/vendor/amqplib/client_0_8/abstract_channel.py
2010-05-27 23:05:26 -07:00

115 lines
3.2 KiB
Python

"""
Code common to Connection and Channel objects.
"""
# Copyright (C) 2007-2008 Barry Pederson <bp@barryp.org>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
from serialization import AMQPWriter
__all__ = [
'AbstractChannel',
]
class AbstractChannel(object):
"""
Superclass for both the Connection, which is treated
as channel 0, and other user-created Channel objects.
The subclasses must have a _METHOD_MAP class property, mapping
between AMQP method signatures and Python methods.
"""
def __init__(self, connection, channel_id):
self.connection = connection
self.channel_id = channel_id
connection.channels[channel_id] = self
self.method_queue = [] # Higher level queue for methods
self.auto_decode = False
def __enter__(self):
"""
Support for Python >= 2.5 'with' statements.
"""
return self
def __exit__(self, type, value, traceback):
"""
Support for Python >= 2.5 'with' statements.
"""
self.close()
def _send_method(self, method_sig, args='', content=None):
"""
Send a method for our channel.
"""
if isinstance(args, AMQPWriter):
args = args.getvalue()
self.connection.method_writer.write_method(self.channel_id,
method_sig, args, content)
def close(self):
"""
Close this Channel or Connection
"""
raise NotImplementedError('Must be overriden in subclass')
def wait(self, allowed_methods=None):
"""
Wait for a method that matches our allowed_methods parameter (the
default value of None means match any method), and dispatch to it.
"""
method_sig, args, content = self.connection._wait_method(
self.channel_id, allowed_methods)
if content \
and self.auto_decode \
and hasattr(content, 'content_encoding'):
try:
content.body = content.body.decode(content.content_encoding)
except Exception:
pass
amqp_method = self._METHOD_MAP.get(method_sig, None)
if amqp_method is None:
raise Exception('Unknown AMQP method (%d, %d)' % method_sig)
if content is None:
return amqp_method(self, args)
else:
return amqp_method(self, args, content)
#
# Placeholder, the concrete implementations will have to
# supply their own versions of _METHOD_MAP
#
_METHOD_MAP = {}