This document describes the current stable version of py-amqp (2.2). For development docs, go here.

Source code for amqp.connection

"""AMQP Connections."""
# 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 __future__ import absolute_import, unicode_literals

import logging
import socket
import uuid
import warnings

from vine import ensure_promise

from . import __version__
from . import sasl
from . import spec
from .abstract_channel import AbstractChannel
from .channel import Channel
from .exceptions import (
    AMQPDeprecationWarning, ChannelError, ResourceError,
    ConnectionForced, ConnectionError, error_for_code,
    RecoverableConnectionError, RecoverableChannelError,
)
from .five import array, items, monotonic, range, values
from .method_framing import frame_handler, frame_writer
from .transport import Transport

try:
    from ssl import SSLError
except ImportError:  # pragma: no cover
    class SSLError(Exception):  # noqa
        pass

W_FORCE_CONNECT = """\
The .{attr} attribute on the connection was accessed before
the connection was established.  This is supported for now, but will
be deprecated in amqp 2.2.0.

Since amqp 2.0 you have to explicitly call Connection.connect()
before using the connection.
"""

START_DEBUG_FMT = """
Start from server, version: %d.%d, properties: %s, mechanisms: %s, locales: %s
""".strip()

__all__ = ['Connection']

AMQP_LOGGER = logging.getLogger('amqp')

#: Default map for :attr:`Connection.library_properties`
LIBRARY_PROPERTIES = {
    'product': 'py-amqp',
    'product_version': __version__,
}

#: Default map for :attr:`Connection.negotiate_capabilities`
NEGOTIATE_CAPABILITIES = {
    'consumer_cancel_notify': True,
    'connection.blocked': True,
    'authentication_failure_close': True,
}


[docs]class Connection(AbstractChannel): """AMQP Connection. The connection class provides methods for a client to establish a network connection to a server, and for both peers to operate the connection thereafter. GRAMMAR:: connection = open-connection *use-connection close-connection open-connection = C:protocol-header S:START C:START-OK *challenge S:TUNE C:TUNE-OK C:OPEN S:OPEN-OK challenge = S:SECURE C:SECURE-OK use-connection = *channel close-connection = C:CLOSE S:CLOSE-OK / S:CLOSE C:CLOSE-OK Create a connection to the specified host, which should be a 'host[:port]', such as 'localhost', or '1.2.3.4:5672' (defaults to 'localhost', if a port is not specified then 5672 is used) Authentication can be controlled by passing one or more `amqp.sasl.SASL` instances as the `authentication` parameter, or by using the userid and password parameters (for AMQPLAIN and PLAIN). The 'ssl' parameter may be simply True/False, or for Python >= 2.6 a dictionary of options to pass to ssl.wrap_socket() such as requiring certain certificates. The "socket_settings" parameter is a dictionary defining tcp settings which will be applied as socket options. """ Channel = Channel #: Mapping of protocol extensions to enable. #: The server will report these in server_properties[capabilities], #: and if a key in this map is present the client will tell the #: server to either enable or disable the capability depending #: on the value set in this map. #: For example with: #: negotiate_capabilities = { #: 'consumer_cancel_notify': True, #: } #: The client will enable this capability if the server reports #: support for it, but if the value is False the client will #: disable the capability. negotiate_capabilities = NEGOTIATE_CAPABILITIES #: These are sent to the server to announce what features #: we support, type of client etc. library_properties = LIBRARY_PROPERTIES #: Final heartbeat interval value (in float seconds) after negotiation heartbeat = None #: Original heartbeat interval value proposed by client. client_heartbeat = None #: Original heartbeat interval proposed by server. server_heartbeat = None #: Time of last heartbeat sent (in monotonic time, if available). last_heartbeat_sent = 0 #: Time of last heartbeat received (in monotonic time, if available). last_heartbeat_received = 0 #: Number of successful writes to socket. bytes_sent = 0 #: Number of successful reads from socket. bytes_recv = 0 #: Number of bytes sent to socket at the last heartbeat check. prev_sent = None #: Number of bytes received from socket at the last heartbeat check. prev_recv = None _METHODS = { spec.method(spec.Connection.Start, 'ooFSS'), spec.method(spec.Connection.OpenOk), spec.method(spec.Connection.Secure, 's'), spec.method(spec.Connection.Tune, 'BlB'), spec.method(spec.Connection.Close, 'BsBB'), spec.method(spec.Connection.Blocked), spec.method(spec.Connection.Unblocked), spec.method(spec.Connection.CloseOk), } _METHODS = {m.method_sig: m for m in _METHODS} connection_errors = ( ConnectionError, socket.error, IOError, OSError, ) channel_errors = (ChannelError,) recoverable_connection_errors = ( RecoverableConnectionError, socket.error, IOError, OSError, ) recoverable_channel_errors = ( RecoverableChannelError, ) def __init__(self, host='localhost:5672', userid='guest', password='guest', login_method=None, login_response=None, authentication=(), virtual_host='/', locale='en_US', client_properties=None, ssl=False, connect_timeout=None, channel_max=None, frame_max=None, heartbeat=0, on_open=None, on_blocked=None, on_unblocked=None, confirm_publish=False, on_tune_ok=None, read_timeout=None, write_timeout=None, socket_settings=None, frame_handler=frame_handler, frame_writer=frame_writer, **kwargs): self._connection_id = uuid.uuid4().hex channel_max = channel_max or 65535 frame_max = frame_max or 131072 if authentication: if isinstance(authentication, sasl.SASL): authentication = (authentication,) self.authentication = authentication elif login_method is not None and login_response is not None: self.authentication = (sasl.RAW(login_method, login_response),) elif userid is not None and password is not None: self.authentication = (sasl.GSSAPI(userid, fail_soft=True), sasl.AMQPLAIN(userid, password), sasl.PLAIN(userid, password)) else: raise ValueError("Must supply authentication or userid/password") self.client_properties = dict( self.library_properties, **client_properties or {} ) self.locale = locale self.host = host self.virtual_host = virtual_host self.on_tune_ok = ensure_promise(on_tune_ok) self.frame_handler_cls = frame_handler self.frame_writer_cls = frame_writer self._handshake_complete = False self.channels = {} # The connection object itself is treated as channel 0 super(Connection, self).__init__(self, 0) self._frame_writer = None self._on_inbound_frame = None self._transport = None # Properties set in the Tune method self.channel_max = channel_max self.frame_max = frame_max self.client_heartbeat = heartbeat self.confirm_publish = confirm_publish self.ssl = ssl self.read_timeout = read_timeout self.write_timeout = write_timeout self.socket_settings = socket_settings # Callbacks self.on_blocked = on_blocked self.on_unblocked = on_unblocked self.on_open = ensure_promise(on_open) self._avail_channel_ids = array('H', range(self.channel_max, 0, -1)) # Properties set in the Start method self.version_major = 0 self.version_minor = 0 self.server_properties = {} self.mechanisms = [] self.locales = [] self.connect_timeout = connect_timeout def __enter__(self): self.connect() return self def __exit__(self, *eargs): self.close()
[docs] def then(self, on_success, on_error=None): return self.on_open.then(on_success, on_error)
def _setup_listeners(self): self._callbacks.update({ spec.Connection.Start: self._on_start, spec.Connection.OpenOk: self._on_open_ok, spec.Connection.Secure: self._on_secure, spec.Connection.Tune: self._on_tune, spec.Connection.Close: self._on_close, spec.Connection.Blocked: self._on_blocked, spec.Connection.Unblocked: self._on_unblocked, spec.Connection.CloseOk: self._on_close_ok, })
[docs] def connect(self, callback=None): # Let the transport.py module setup the actual # socket connection to the broker. # if self.connected: return callback() if callback else None self.transport = self.Transport( self.host, self.connect_timeout, self.ssl, self.read_timeout, self.write_timeout, socket_settings=self.socket_settings, ) self.transport.connect() self.on_inbound_frame = self.frame_handler_cls( self, self.on_inbound_method) self.frame_writer = self.frame_writer_cls(self, self.transport) while not self._handshake_complete: self.drain_events(timeout=self.connect_timeout)
def _warn_force_connect(self, attr): warnings.warn(AMQPDeprecationWarning( W_FORCE_CONNECT.format(attr=attr))) @property def transport(self): if self._transport is None: self._warn_force_connect('transport') self.connect() return self._transport @transport.setter def transport(self, transport): self._transport = transport @property def on_inbound_frame(self): if self._on_inbound_frame is None: self._warn_force_connect('on_inbound_frame') self.connect() return self._on_inbound_frame @on_inbound_frame.setter def on_inbound_frame(self, on_inbound_frame): self._on_inbound_frame = on_inbound_frame @property def frame_writer(self): if self._frame_writer is None: self._warn_force_connect('frame_writer') self.connect() return self._frame_writer @frame_writer.setter def frame_writer(self, frame_writer): self._frame_writer = frame_writer def _on_start(self, version_major, version_minor, server_properties, mechanisms, locales, argsig='FsSs'): client_properties = self.client_properties self.version_major = version_major self.version_minor = version_minor self.server_properties = server_properties self.mechanisms = mechanisms.split(b' ') self.locales = locales.split(' ') AMQP_LOGGER.debug( START_DEBUG_FMT, self.version_major, self.version_minor, self.server_properties, self.mechanisms, self.locales, ) # Negotiate protocol extensions (capabilities) scap = server_properties.get('capabilities') or {} cap = client_properties.setdefault('capabilities', {}) cap.update({ wanted_cap: enable_cap for wanted_cap, enable_cap in items(self.negotiate_capabilities) if scap.get(wanted_cap) }) if not cap: # no capabilities, server may not react well to having # this key present in client_properties, so we remove it. client_properties.pop('capabilities', None) for authentication in self.authentication: if authentication.mechanism in self.mechanisms: login_response = authentication.start(self) if login_response is not NotImplemented: break else: raise ConnectionError( "Couldn't find appropriate auth mechanism " "(can offer: {0}; available: {1})".format( b", ".join(m.mechanism for m in self.authentication if m.mechanism).decode(), b", ".join(self.mechanisms).decode())) self.send_method( spec.Connection.StartOk, argsig, (client_properties, authentication.mechanism, login_response, self.locale), ) def _on_secure(self, challenge): pass def _on_tune(self, channel_max, frame_max, server_heartbeat, argsig='BlB'): client_heartbeat = self.client_heartbeat or 0 self.channel_max = channel_max or self.channel_max self.frame_max = frame_max or self.frame_max self.server_heartbeat = server_heartbeat or 0 # negotiate the heartbeat interval to the smaller of the # specified values if self.server_heartbeat == 0 or client_heartbeat == 0: self.heartbeat = max(self.server_heartbeat, client_heartbeat) else: self.heartbeat = min(self.server_heartbeat, client_heartbeat) # Ignore server heartbeat if client_heartbeat is disabled if not self.client_heartbeat: self.heartbeat = 0 self.send_method( spec.Connection.TuneOk, argsig, (self.channel_max, self.frame_max, self.heartbeat), callback=self._on_tune_sent, ) def _on_tune_sent(self, argsig='ssb'): self.send_method( spec.Connection.Open, argsig, (self.virtual_host, '', False), ) def _on_open_ok(self): self._handshake_complete = True self.on_open(self)
[docs] def Transport(self, host, connect_timeout, ssl=False, read_timeout=None, write_timeout=None, socket_settings=None, **kwargs): return Transport( host, connect_timeout=connect_timeout, ssl=ssl, read_timeout=read_timeout, write_timeout=write_timeout, socket_settings=socket_settings, **kwargs)
@property def connected(self): return self._transport and self._transport.connected
[docs] def collect(self): try: if self._transport: self._transport.close() temp_list = [x for x in values(self.channels or {}) if x is not self] for ch in temp_list: ch.collect() except socket.error: pass # connection already closed on the other end finally: self._transport = self.connection = self.channels = None
def _get_free_channel_id(self): try: return self._avail_channel_ids.pop() except IndexError: raise ResourceError( 'No free channel ids, current={0}, channel_max={1}'.format( len(self.channels), self.channel_max), spec.Channel.Open) def _claim_channel_id(self, channel_id): try: return self._avail_channel_ids.remove(channel_id) except ValueError: raise ConnectionError('Channel %r already open' % (channel_id,))
[docs] def channel(self, channel_id=None, callback=None): """Create new channel. Fetch a Channel object identified by the numeric channel_id, or create that object if it doesn't already exist. """ if self.channels is not None: try: return self.channels[channel_id] except KeyError: channel = self.Channel(self, channel_id, on_open=callback) channel.open() return channel raise RecoverableConnectionError('Connection already closed.')
[docs] def is_alive(self): raise NotImplementedError('Use AMQP heartbeats')
[docs] def drain_events(self, timeout=None): # read until message is ready while not self.blocking_read(timeout): pass
[docs] def blocking_read(self, timeout=None): with self.transport.having_timeout(timeout): frame = self.transport.read_frame() return self.on_inbound_frame(frame)
[docs] def on_inbound_method(self, channel_id, method_sig, payload, content): return self.channels[channel_id].dispatch_method( method_sig, payload, content, )
[docs] def close(self, reply_code=0, reply_text='', method_sig=(0, 0), argsig='BsBB'): """Request a connection close. This method indicates that the sender wants to close the connection. This may be due to internal conditions (e.g. a forced shut-down) or due to an error handling a specific method, i.e. an exception. When a close is due to an exception, the sender provides the class and method id of the method which caused the exception. RULE: After sending this method any received method except the Close-OK method MUST be discarded. RULE: The peer sending this method MAY use a counter or timeout to detect failure of the other peer to respond correctly with the Close-OK method. RULE: When a server receives the Close method from a client it MUST delete all server-side resources associated with the client's context. A client CANNOT reconnect to a context after sending or receiving a Close method. PARAMETERS: reply_code: short The reply code. The AMQ reply codes are defined in AMQ RFC 011. reply_text: shortstr The localised reply text. This text can be logged as an aid to resolving issues. class_id: short failing method class When the close is provoked by a method exception, this is the class of the method. method_id: short failing method ID When the close is provoked by a method exception, this is the ID of the method. """ if self._transport is None: # already closed return return self.send_method( spec.Connection.Close, argsig, (reply_code, reply_text, method_sig[0], method_sig[1]), wait=spec.Connection.CloseOk, )
def _on_close(self, reply_code, reply_text, class_id, method_id): """Request a connection close. This method indicates that the sender wants to close the connection. This may be due to internal conditions (e.g. a forced shut-down) or due to an error handling a specific method, i.e. an exception. When a close is due to an exception, the sender provides the class and method id of the method which caused the exception. RULE: After sending this method any received method except the Close-OK method MUST be discarded. RULE: The peer sending this method MAY use a counter or timeout to detect failure of the other peer to respond correctly with the Close-OK method. RULE: When a server receives the Close method from a client it MUST delete all server-side resources associated with the client's context. A client CANNOT reconnect to a context after sending or receiving a Close method. PARAMETERS: reply_code: short The reply code. The AMQ reply codes are defined in AMQ RFC 011. reply_text: shortstr The localised reply text. This text can be logged as an aid to resolving issues. class_id: short failing method class When the close is provoked by a method exception, this is the class of the method. method_id: short failing method ID When the close is provoked by a method exception, this is the ID of the method. """ self._x_close_ok() raise error_for_code(reply_code, reply_text, (class_id, method_id), ConnectionError) def _x_close_ok(self): """Confirm a connection close. This method confirms a Connection.Close method and tells the recipient that it is safe to release resources for the connection and close the socket. RULE: A peer that detects a socket closure without having received a Close-Ok handshake method SHOULD log the error. """ self.send_method(spec.Connection.CloseOk, callback=self._on_close_ok) def _on_close_ok(self): """Confirm a connection close. This method confirms a Connection.Close method and tells the recipient that it is safe to release resources for the connection and close the socket. RULE: A peer that detects a socket closure without having received a Close-Ok handshake method SHOULD log the error. """ self.collect() def _on_blocked(self): """Callback called when connection blocked. Notes: This is an RabbitMQ Extension. """ reason = 'connection blocked, see broker logs' if self.on_blocked: return self.on_blocked(reason) def _on_unblocked(self): if self.on_unblocked: return self.on_unblocked()
[docs] def send_heartbeat(self): self.frame_writer(8, 0, None, None, None)
[docs] def heartbeat_tick(self, rate=2): """Send heartbeat packets if necessary. Raises: ~amqp.exceptions.ConnectionForvced: if none have been received recently. Note: This should be called frequently, on the order of once per second. Keyword Arguments: rate (int): Previously used, but ignored now. """ AMQP_LOGGER.debug('heartbeat_tick : for connection %s', self._connection_id) if not self.heartbeat: return # treat actual data exchange in either direction as a heartbeat sent_now = self.bytes_sent recv_now = self.bytes_recv if self.prev_sent is None or self.prev_sent != sent_now: self.last_heartbeat_sent = monotonic() if self.prev_recv is None or self.prev_recv != recv_now: self.last_heartbeat_received = monotonic() now = monotonic() AMQP_LOGGER.debug( 'heartbeat_tick : Prev sent/recv: %s/%s, ' 'now - %s/%s, monotonic - %s, ' 'last_heartbeat_sent - %s, heartbeat int. - %s ' 'for connection %s', self.prev_sent, self.prev_recv, sent_now, recv_now, now, self.last_heartbeat_sent, self.heartbeat, self._connection_id, ) self.prev_sent, self.prev_recv = sent_now, recv_now # send a heartbeat if it's time to do so if now > self.last_heartbeat_sent + self.heartbeat: AMQP_LOGGER.debug( 'heartbeat_tick: sending heartbeat for connection %s', self._connection_id) self.send_heartbeat() self.last_heartbeat_sent = monotonic() # if we've missed two intervals' heartbeats, fail; this gives the # server enough time to send heartbeats a little late if (self.last_heartbeat_received and self.last_heartbeat_received + 2 * self.heartbeat < monotonic()): raise ConnectionForced('Too many heartbeats missed')
@property def sock(self): return self.transport.sock @property def server_capabilities(self): return self.server_properties.get('capabilities') or {}