This document describes the current stable version of Kombu (4.0). 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 io import BytesIO
from vine import ensure_promise
from . import __version__
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 .serialization import _write_table
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,
}
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)
If login_response is not specified, one is built up for you from
userid and password if they are present.
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='AMQPLAIN', login_response=None,
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 (login_response is None) \
and (userid is not None) \
and (password is not None):
login_response = BytesIO()
_write_table({'LOGIN': userid, 'PASSWORD': password},
login_response.write, [])
# Skip the length at the beginning
login_response = login_response.getvalue()[4:]
self.client_properties = dict(
self.library_properties, **client_properties or {}
)
self.login_method = login_method
self.login_response = login_response
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()
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(' ')
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)
self.send_method(
spec.Connection.StartOk, argsig,
(client_properties, self.login_method,
self.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:
self.transport.close()
temp_list = [x for x in values(self.channels) 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 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 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 {}
