"""The blocking connection adapter module implements blocking semantics on top of Pika's core AMQP driver. While most of the asynchronous expectations are removed when using the blocking connection adapter, it attempts to remain true to the asynchronous RPC nature of the AMQP protocol, supporting server sent RPC commands. The user facing classes in the module consist of the :py:class:`~pika.adapters.blocking_connection.BlockingConnection` and the :class:`~pika.adapters.blocking_connection.BlockingChannel` classes. """ # Suppress too-many-lines # pylint: disable=C0302 # Disable "access to protected member warnings: this wrapper implementation is # a friend of those instances # pylint: disable=W0212 from collections import namedtuple, deque import contextlib import functools import logging import threading import pika.compat as compat import pika.exceptions as exceptions import pika.spec import pika.validators as validators from pika.adapters.utils import connection_workflow # NOTE: import SelectConnection after others to avoid circular depenency from pika.adapters import select_connection from pika.exchange_type import ExchangeType LOGGER = logging.getLogger(__name__) class _CallbackResult(object): """ CallbackResult is a non-thread-safe implementation for receiving callback results; INTERNAL USE ONLY! """ __slots__ = ('_value_class', '_ready', '_values') def __init__(self, value_class=None): """ :param callable value_class: only needed if the CallbackResult instance will be used with `set_value_once` and `append_element`. *args and **kwargs of the value setter methods will be passed to this class. """ self._value_class = value_class self._ready = None self._values = None self.reset() def reset(self): """Reset value, but not _value_class""" self._ready = False self._values = None def __bool__(self): """ Called by python runtime to implement truth value testing and the built-in operation bool(); NOTE: python 3.x """ return self.is_ready() # python 2.x version of __bool__ __nonzero__ = __bool__ def __enter__(self): """ Entry into context manager that automatically resets the object on exit; this usage pattern helps garbage-collection by eliminating potential circular references. """ return self def __exit__(self, *args, **kwargs): """Reset value""" self.reset() def is_ready(self): """ :returns: True if the object is in a signaled state :rtype: bool """ return self._ready @property def ready(self): """True if the object is in a signaled state""" return self._ready def signal_once(self, *_args, **_kwargs): """ Set as ready :raises AssertionError: if result was already signalled """ assert not self._ready, '_CallbackResult was already set' self._ready = True def set_value_once(self, *args, **kwargs): """ Set as ready with value; the value may be retrieved via the `value` property getter :raises AssertionError: if result was already set """ self.signal_once() try: self._values = (self._value_class(*args, **kwargs),) except Exception: LOGGER.error( "set_value_once failed: value_class=%r; args=%r; kwargs=%r", self._value_class, args, kwargs) raise def append_element(self, *args, **kwargs): """Append an element to values""" assert not self._ready or isinstance(self._values, list), ( '_CallbackResult state is incompatible with append_element: ' 'ready=%r; values=%r' % (self._ready, self._values)) try: value = self._value_class(*args, **kwargs) except Exception: LOGGER.error( "append_element failed: value_class=%r; args=%r; kwargs=%r", self._value_class, args, kwargs) raise if self._values is None: self._values = [value] else: self._values.append(value) self._ready = True @property def value(self): """ :returns: a reference to the value that was set via `set_value_once` :rtype: object :raises AssertionError: if result was not set or value is incompatible with `set_value_once` """ assert self._ready, '_CallbackResult was not set' assert isinstance(self._values, tuple) and len(self._values) == 1, ( '_CallbackResult value is incompatible with set_value_once: %r' % (self._values,)) return self._values[0] @property def elements(self): """ :returns: a reference to the list containing one or more elements that were added via `append_element` :rtype: list :raises AssertionError: if result was not set or value is incompatible with `append_element` """ assert self._ready, '_CallbackResult was not set' assert isinstance(self._values, list) and self._values, ( '_CallbackResult value is incompatible with append_element: %r' % (self._values,)) return self._values class _IoloopTimerContext(object): """Context manager for registering and safely unregistering a SelectConnection ioloop-based timer """ def __init__(self, duration, connection): """ :param float duration: non-negative timer duration in seconds :param select_connection.SelectConnection connection: """ assert hasattr(connection, '_adapter_call_later'), connection self._duration = duration self._connection = connection self._callback_result = _CallbackResult() self._timer_handle = None def __enter__(self): """Register a timer""" self._timer_handle = self._connection._adapter_call_later( self._duration, self._callback_result.signal_once) return self def __exit__(self, *_args, **_kwargs): """Unregister timer if it hasn't fired yet""" if not self._callback_result: self._connection._adapter_remove_timeout(self._timer_handle) self._timer_handle = None def is_ready(self): """ :returns: True if timer has fired, False otherwise :rtype: bool """ return self._callback_result.is_ready() class _TimerEvt(object): """Represents a timer created via `BlockingConnection.call_later`""" __slots__ = ('timer_id', '_callback') def __init__(self, callback): """ :param callback: see callback in `BlockingConnection.call_later` """ self._callback = callback # Will be set to timer id returned from the underlying implementation's # `_adapter_call_later` method self.timer_id = None def __repr__(self): return '<%s timer_id=%s callback=%s>' % (self.__class__.__name__, self.timer_id, self._callback) def dispatch(self): """Dispatch the user's callback method""" LOGGER.debug('_TimerEvt.dispatch: invoking callback=%r', self._callback) self._callback() class _ConnectionBlockedUnblockedEvtBase(object): """Base class for `_ConnectionBlockedEvt` and `_ConnectionUnblockedEvt`""" __slots__ = ('_callback', '_method_frame') def __init__(self, callback, method_frame): """ :param callback: see callback parameter in `BlockingConnection.add_on_connection_blocked_callback` and `BlockingConnection.add_on_connection_unblocked_callback` :param pika.frame.Method method_frame: with method_frame.method of type `pika.spec.Connection.Blocked` or `pika.spec.Connection.Unblocked` """ self._callback = callback self._method_frame = method_frame def __repr__(self): return '<%s callback=%s, frame=%s>' % ( self.__class__.__name__, self._callback, self._method_frame) def dispatch(self): """Dispatch the user's callback method""" self._callback(self._method_frame) class _ConnectionBlockedEvt(_ConnectionBlockedUnblockedEvtBase): """Represents a Connection.Blocked notification from RabbitMQ broker`""" class _ConnectionUnblockedEvt(_ConnectionBlockedUnblockedEvtBase): """Represents a Connection.Unblocked notification from RabbitMQ broker`""" class BlockingConnection(object): """The BlockingConnection creates a layer on top of Pika's asynchronous core providing methods that will block until their expected response has returned. Due to the asynchronous nature of the `Basic.Deliver` and `Basic.Return` calls from RabbitMQ to your application, you can still implement continuation-passing style asynchronous methods if you'd like to receive messages from RabbitMQ using :meth:`basic_consume ` or if you want to be notified of a delivery failure when using :meth:`basic_publish `. For more information about communicating with the blocking_connection adapter, be sure to check out the :class:`BlockingChannel ` class which implements the :class:`Channel ` based communication for the blocking_connection adapter. To prevent recursion/reentrancy, the blocking connection and channel implementations queue asynchronously-delivered events received in nested context (e.g., while waiting for `BlockingConnection.channel` or `BlockingChannel.queue_declare` to complete), dispatching them synchronously once nesting returns to the desired context. This concerns all callbacks, such as those registered via `BlockingConnection.call_later`, `BlockingConnection.add_on_connection_blocked_callback`, `BlockingConnection.add_on_connection_unblocked_callback`, `BlockingChannel.basic_consume`, etc. Blocked Connection deadlock avoidance: when RabbitMQ becomes low on resources, it emits Connection.Blocked (AMQP extension) to the client connection when client makes a resource-consuming request on that connection or its channel (e.g., `Basic.Publish`); subsequently, RabbitMQ suspsends processing requests from that connection until the affected resources are restored. See http://www.rabbitmq.com/connection-blocked.html. This may impact `BlockingConnection` and `BlockingChannel` operations in a way that users might not be expecting. For example, if the user dispatches `BlockingChannel.basic_publish` in non-publisher-confirmation mode while RabbitMQ is in this low-resource state followed by a synchronous request (e.g., `BlockingConnection.channel`, `BlockingChannel.consume`, `BlockingChannel.basic_consume`, etc.), the synchronous request will block indefinitely (until Connection.Unblocked) waiting for RabbitMQ to reply. If the blocked state persists for a long time, the blocking operation will appear to hang. In this state, `BlockingConnection` instance and its channels will not dispatch user callbacks. SOLUTION: To break this potential deadlock, applications may configure the `blocked_connection_timeout` connection parameter when instantiating `BlockingConnection`. Upon blocked connection timeout, this adapter will raise ConnectionBlockedTimeout exception`. See `pika.connection.ConnectionParameters` documentation to learn more about the `blocked_connection_timeout` configuration. """ # Connection-closing callback args _OnClosedArgs = namedtuple('BlockingConnection__OnClosedArgs', 'connection error') # Channel-opened callback args _OnChannelOpenedArgs = namedtuple('BlockingConnection__OnChannelOpenedArgs', 'channel') def __init__(self, parameters=None, _impl_class=None): """Create a new instance of the Connection object. :param None | pika.connection.Parameters | sequence parameters: Connection parameters instance or non-empty sequence of them. If None, a `pika.connection.Parameters` instance will be created with default settings. See `pika.AMQPConnectionWorkflow` for more details about multiple parameter configurations and retries. :param _impl_class: for tests/debugging only; implementation class; None=default :raises RuntimeError: """ # Used for mutual exclusion to avoid race condition between # BlockingConnection._cleanup() and another thread calling # BlockingConnection.add_callback_threadsafe() against a closed # ioloop. self._cleanup_mutex = threading.Lock() # Used by the _acquire_event_dispatch decorator; when already greater # than 0, event dispatch is already acquired higher up the call stack self._event_dispatch_suspend_depth = 0 # Connection-specific events that are ready for dispatch: _TimerEvt, # _ConnectionBlockedEvt, _ConnectionUnblockedEvt self._ready_events = deque() # Channel numbers of channels that are requesting a call to their # BlockingChannel._dispatch_events method; See # `_request_channel_dispatch` self._channels_pending_dispatch = set() # Receives on_close_callback args from Connection self._closed_result = _CallbackResult(self._OnClosedArgs) # Perform connection workflow self._impl = None # so that attribute is created in case below raises self._impl = self._create_connection(parameters, _impl_class) self._impl.add_on_close_callback(self._closed_result.set_value_once) def __repr__(self): return '<%s impl=%r>' % (self.__class__.__name__, self._impl) def __enter__(self): # Prepare `with` context return self def __exit__(self, exc_type, value, traceback): # Close connection after `with` context if self.is_open: self.close() def _cleanup(self): """Clean up members that might inhibit garbage collection """ with self._cleanup_mutex: if self._impl is not None: self._impl.ioloop.close() self._ready_events.clear() self._closed_result.reset() @contextlib.contextmanager def _acquire_event_dispatch(self): """ Context manager that controls access to event dispatcher for preventing reentrancy. The "as" value is True if the managed code block owns the event dispatcher and False if caller higher up in the call stack already owns it. Only managed code that gets ownership (got True) is permitted to dispatch """ try: # __enter__ part self._event_dispatch_suspend_depth += 1 yield self._event_dispatch_suspend_depth == 1 finally: # __exit__ part self._event_dispatch_suspend_depth -= 1 def _create_connection(self, configs, impl_class): """Run connection workflow, blocking until it completes. :param None | pika.connection.Parameters | sequence configs: Connection parameters instance or non-empty sequence of them. :param None | SelectConnection impl_class: for tests/debugging only; implementation class; :rtype: impl_class :raises: exception on failure """ if configs is None: configs = (pika.connection.Parameters(),) if isinstance(configs, pika.connection.Parameters): configs = (configs,) if not configs: raise ValueError('Expected a non-empty sequence of connection ' 'parameters, but got {!r}.'.format(configs)) # Connection workflow completion args # `result` may be an instance of connection on success or exception on # failure. on_cw_done_result = _CallbackResult( namedtuple('BlockingConnection_OnConnectionWorkflowDoneArgs', 'result')) impl_class = impl_class or select_connection.SelectConnection ioloop = select_connection.IOLoop() ioloop.activate_poller() try: impl_class.create_connection( configs, on_done=on_cw_done_result.set_value_once, custom_ioloop=ioloop) while not on_cw_done_result.ready: ioloop.poll() ioloop.process_timeouts() if isinstance(on_cw_done_result.value.result, BaseException): error = on_cw_done_result.value.result LOGGER.error('Connection workflow failed: %r', error) raise self._reap_last_connection_workflow_error(error) else: LOGGER.info('Connection workflow succeeded: %r', on_cw_done_result.value.result) return on_cw_done_result.value.result except Exception: LOGGER.exception('Error in _create_connection().') ioloop.close() self._cleanup() raise @staticmethod def _reap_last_connection_workflow_error(error): """Extract exception value from the last connection attempt :param Exception error: error passed by the `AMQPConnectionWorkflow` completion callback. :returns: Exception value from the last connection attempt :rtype: Exception """ if isinstance(error, connection_workflow.AMQPConnectionWorkflowFailed): # Extract exception value from the last connection attempt error = error.exceptions[-1] if isinstance(error, connection_workflow.AMQPConnectorSocketConnectError): error = exceptions.AMQPConnectionError(error) elif isinstance(error, connection_workflow.AMQPConnectorPhaseErrorBase): error = error.exception return error def _flush_output(self, *waiters): """ Flush output and process input while waiting for any of the given callbacks to return true. The wait is aborted upon connection-close. Otherwise, processing continues until the output is flushed AND at least one of the callbacks returns true. If there are no callbacks, then processing ends when all output is flushed. :param waiters: sequence of zero or more callables taking no args and returning true when it's time to stop processing. Their results are OR'ed together. :raises: exceptions passed by impl if opening of connection fails or connection closes. """ if self.is_closed: raise exceptions.ConnectionWrongStateError() # Conditions for terminating the processing loop: # connection closed # OR # empty outbound buffer and no waiters # OR # empty outbound buffer and any waiter is ready is_done = (lambda: self._closed_result.ready or ((not self._impl._transport or self._impl._get_write_buffer_size() == 0) and (not waiters or any(ready() for ready in waiters)))) # Process I/O until our completion condition is satisfied while not is_done(): self._impl.ioloop.poll() self._impl.ioloop.process_timeouts() if self._closed_result.ready: try: if not isinstance(self._closed_result.value.error, exceptions.ConnectionClosedByClient): LOGGER.error('Unexpected connection close detected: %r', self._closed_result.value.error) raise self._closed_result.value.error else: LOGGER.info('User-initiated close: result=%r', self._closed_result.value) finally: self._cleanup() def _request_channel_dispatch(self, channel_number): """Called by BlockingChannel instances to request a call to their _dispatch_events method or to terminate `process_data_events`; BlockingConnection will honor these requests from a safe context. :param int channel_number: positive channel number to request a call to the channel's `_dispatch_events`; a negative channel number to request termination of `process_data_events` """ self._channels_pending_dispatch.add(channel_number) def _dispatch_channel_events(self): """Invoke the `_dispatch_events` method on open channels that requested it """ if not self._channels_pending_dispatch: return with self._acquire_event_dispatch() as dispatch_acquired: if not dispatch_acquired: # Nested dispatch or dispatch blocked higher in call stack return candidates = list(self._channels_pending_dispatch) self._channels_pending_dispatch.clear() for channel_number in candidates: if channel_number < 0: # This was meant to terminate process_data_events continue try: impl_channel = self._impl._channels[channel_number] except KeyError: continue if impl_channel.is_open: impl_channel._get_cookie()._dispatch_events() def _on_timer_ready(self, evt): """Handle expiry of a timer that was registered via `_adapter_call_later()` :param _TimerEvt evt: """ self._ready_events.append(evt) def _on_threadsafe_callback(self, user_callback): """Handle callback that was registered via `self._impl._adapter_add_callback_threadsafe`. :param user_callback: callback passed to our `add_callback_threadsafe` by the application. """ # Turn it into a 0-delay timeout to take advantage of our existing logic # that deals with reentrancy self.call_later(0, user_callback) def _on_connection_blocked(self, user_callback, _impl, method_frame): """Handle Connection.Blocked notification from RabbitMQ broker :param callable user_callback: callback passed to `add_on_connection_blocked_callback` :param select_connection.SelectConnection _impl: :param pika.frame.Method method_frame: method frame having `method` member of type `pika.spec.Connection.Blocked` """ self._ready_events.append( _ConnectionBlockedEvt(user_callback, method_frame)) def _on_connection_unblocked(self, user_callback, _impl, method_frame): """Handle Connection.Unblocked notification from RabbitMQ broker :param callable user_callback: callback passed to `add_on_connection_unblocked_callback` :param select_connection.SelectConnection _impl: :param pika.frame.Method method_frame: method frame having `method` member of type `pika.spec.Connection.Blocked` """ self._ready_events.append( _ConnectionUnblockedEvt(user_callback, method_frame)) def _dispatch_connection_events(self): """Dispatch ready connection events""" if not self._ready_events: return with self._acquire_event_dispatch() as dispatch_acquired: if not dispatch_acquired: # Nested dispatch or dispatch blocked higher in call stack return # Limit dispatch to the number of currently ready events to avoid # getting stuck in this loop for _ in compat.xrange(len(self._ready_events)): try: evt = self._ready_events.popleft() except IndexError: # Some events (e.g., timers) must have been cancelled break evt.dispatch() def add_on_connection_blocked_callback(self, callback): """RabbitMQ AMQP extension - Add a callback to be notified when the connection gets blocked (`Connection.Blocked` received from RabbitMQ) due to the broker running low on resources (memory or disk). In this state RabbitMQ suspends processing incoming data until the connection is unblocked, so it's a good idea for publishers receiving this notification to suspend publishing until the connection becomes unblocked. NOTE: due to the blocking nature of BlockingConnection, if it's sending outbound data while the connection is/becomes blocked, the call may remain blocked until the connection becomes unblocked, if ever. You may use `ConnectionParameters.blocked_connection_timeout` to abort a BlockingConnection method call with an exception when the connection remains blocked longer than the given timeout value. See also `Connection.add_on_connection_unblocked_callback()` See also `ConnectionParameters.blocked_connection_timeout`. :param callable callback: Callback to call on `Connection.Blocked`, having the signature `callback(connection, pika.frame.Method)`, where connection is the `BlockingConnection` instance and the method frame's `method` member is of type `pika.spec.Connection.Blocked` """ self._impl.add_on_connection_blocked_callback( functools.partial(self._on_connection_blocked, functools.partial(callback, self))) def add_on_connection_unblocked_callback(self, callback): """RabbitMQ AMQP extension - Add a callback to be notified when the connection gets unblocked (`Connection.Unblocked` frame is received from RabbitMQ) letting publishers know it's ok to start publishing again. :param callable callback: Callback to call on Connection.Unblocked`, having the signature `callback(connection, pika.frame.Method)`, where connection is the `BlockingConnection` instance and the method frame's `method` member is of type `pika.spec.Connection.Unblocked` """ self._impl.add_on_connection_unblocked_callback( functools.partial(self._on_connection_unblocked, functools.partial(callback, self))) def call_later(self, delay, callback): """Create a single-shot timer to fire after delay seconds. Do not confuse with Tornado's timeout where you pass in the time you want to have your callback called. Only pass in the seconds until it's to be called. NOTE: the timer callbacks are dispatched only in the scope of specially-designated methods: see `BlockingConnection.process_data_events()` and `BlockingChannel.start_consuming()`. :param float delay: The number of seconds to wait to call callback :param callable callback: The callback method with the signature callback() :returns: Opaque timer id :rtype: int """ validators.require_callback(callback) evt = _TimerEvt(callback=callback) timer_id = self._impl._adapter_call_later( delay, functools.partial(self._on_timer_ready, evt)) evt.timer_id = timer_id return timer_id def add_callback_threadsafe(self, callback): """Requests a call to the given function as soon as possible in the context of this connection's thread. NOTE: This is the only thread-safe method in `BlockingConnection`. All other manipulations of `BlockingConnection` must be performed from the connection's thread. NOTE: the callbacks are dispatched only in the scope of specially-designated methods: see `BlockingConnection.process_data_events()` and `BlockingChannel.start_consuming()`. For example, a thread may request a call to the `BlockingChannel.basic_ack` method of a `BlockingConnection` that is running in a different thread via:: connection.add_callback_threadsafe( functools.partial(channel.basic_ack, delivery_tag=...)) NOTE: if you know that the requester is running on the same thread as the connection it is more efficient to use the `BlockingConnection.call_later()` method with a delay of 0. :param callable callback: The callback method; must be callable :raises pika.exceptions.ConnectionWrongStateError: if connection is closed """ with self._cleanup_mutex: # NOTE: keep in mind that we may be called from another thread and # this mutex only synchronizes us with our connection cleanup logic, # so a simple check for "is_closed" is pretty much all we're allowed # to do here besides calling the only thread-safe method # _adapter_add_callback_threadsafe(). if self.is_closed: raise exceptions.ConnectionWrongStateError( 'BlockingConnection.add_callback_threadsafe() called on ' 'closed or closing connection.') self._impl._adapter_add_callback_threadsafe( functools.partial(self._on_threadsafe_callback, callback)) def remove_timeout(self, timeout_id): """Remove a timer if it's still in the timeout stack :param timeout_id: The opaque timer id to remove """ # Remove from the impl's timeout stack self._impl._adapter_remove_timeout(timeout_id) # Remove from ready events, if the timer fired already for i, evt in enumerate(self._ready_events): if isinstance(evt, _TimerEvt) and evt.timer_id == timeout_id: index_to_remove = i break else: # Not found return del self._ready_events[index_to_remove] def update_secret(self, new_secret, reason): """RabbitMQ AMQP extension - This method updates the secret used to authenticate this connection. It is used when secrets have an expiration date and need to be renewed, like OAuth 2 tokens. :param string new_secret: The new secret :param string reason: The reason for the secret update :raises pika.exceptions.ConnectionWrongStateError: if connection is not open. """ result = _CallbackResult() self._impl.update_secret(new_secret, reason, result.signal_once) self._flush_output(result.is_ready) def close(self, reply_code=200, reply_text='Normal shutdown'): """Disconnect from RabbitMQ. If there are any open channels, it will attempt to close them prior to fully disconnecting. Channels which have active consumers will attempt to send a Basic.Cancel to RabbitMQ to cleanly stop the delivery of messages prior to closing the channel. :param int reply_code: The code number for the close :param str reply_text: The text reason for the close :raises pika.exceptions.ConnectionWrongStateError: if called on a closed connection (NEW in v1.0.0) """ if not self.is_open: msg = '{}.close({}, {!r}) called on closed connection.'.format( self.__class__.__name__, reply_code, reply_text) LOGGER.error(msg) raise exceptions.ConnectionWrongStateError(msg) LOGGER.info('Closing connection (%s): %s', reply_code, reply_text) # Close channels that remain opened for impl_channel in compat.dictvalues(self._impl._channels): channel = impl_channel._get_cookie() if channel.is_open: try: channel.close(reply_code, reply_text) except exceptions.ChannelClosed as exc: # Log and suppress broker-closed channel LOGGER.warning( 'Got ChannelClosed while closing channel ' 'from connection.close: %r', exc) # Close the connection self._impl.close(reply_code, reply_text) self._flush_output(self._closed_result.is_ready) def process_data_events(self, time_limit=0): """Will make sure that data events are processed. Dispatches timer and channel callbacks if not called from the scope of BlockingConnection or BlockingChannel callback. Your app can block on this method. If your application maintains a long-lived publisher connection, this method should be called periodically in order to respond to heartbeats and other data events. See `examples/long_running_publisher.py` for an example. :param float time_limit: suggested upper bound on processing time in seconds. The actual blocking time depends on the granularity of the underlying ioloop. Zero means return as soon as possible. None means there is no limit on processing time and the function will block until I/O produces actionable events. Defaults to 0 for backward compatibility. This parameter is NEW in pika 0.10.0. """ with self._acquire_event_dispatch() as dispatch_acquired: # Check if we can actually process pending events common_terminator = lambda: bool(dispatch_acquired and (self._channels_pending_dispatch or self._ready_events)) if time_limit is None: self._flush_output(common_terminator) else: with _IoloopTimerContext(time_limit, self._impl) as timer: self._flush_output(timer.is_ready, common_terminator) if self._ready_events: self._dispatch_connection_events() if self._channels_pending_dispatch: self._dispatch_channel_events() def sleep(self, duration): """A safer way to sleep than calling time.sleep() directly that would keep the adapter from ignoring frames sent from the broker. The connection will "sleep" or block the number of seconds specified in duration in small intervals. :param float duration: The time to sleep in seconds """ assert duration >= 0, duration deadline = compat.time_now() + duration time_limit = duration # Process events at least once while True: self.process_data_events(time_limit) time_limit = deadline - compat.time_now() if time_limit <= 0: break def channel(self, channel_number=None): """Create a new channel with the next available channel number or pass in a channel number to use. Must be non-zero if you would like to specify but it is recommended that you let Pika manage the channel numbers. :rtype: pika.adapters.blocking_connection.BlockingChannel """ with _CallbackResult(self._OnChannelOpenedArgs) as opened_args: impl_channel = self._impl.channel( channel_number=channel_number, on_open_callback=opened_args.set_value_once) # Create our proxy channel channel = BlockingChannel(impl_channel, self) # Link implementation channel with our proxy channel impl_channel._set_cookie(channel) # Drive I/O until Channel.Open-ok channel._flush_output(opened_args.is_ready) return channel # # Connections state properties # @property def is_closed(self): """ Returns a boolean reporting the current connection state. """ return self._impl.is_closed @property def is_open(self): """ Returns a boolean reporting the current connection state. """ return self._impl.is_open # # Properties that reflect server capabilities for the current connection # @property def basic_nack_supported(self): """Specifies if the server supports basic.nack on the active connection. :rtype: bool """ return self._impl.basic_nack @property def consumer_cancel_notify_supported(self): """Specifies if the server supports consumer cancel notification on the active connection. :rtype: bool """ return self._impl.consumer_cancel_notify @property def exchange_exchange_bindings_supported(self): """Specifies if the active connection supports exchange to exchange bindings. :rtype: bool """ return self._impl.exchange_exchange_bindings @property def publisher_confirms_supported(self): """Specifies if the active connection can use publisher confirmations. :rtype: bool """ return self._impl.publisher_confirms # Legacy property names for backward compatibility basic_nack = basic_nack_supported consumer_cancel_notify = consumer_cancel_notify_supported exchange_exchange_bindings = exchange_exchange_bindings_supported publisher_confirms = publisher_confirms_supported class _ChannelPendingEvt(object): """Base class for BlockingChannel pending events""" class _ConsumerDeliveryEvt(_ChannelPendingEvt): """This event represents consumer message delivery `Basic.Deliver`; it contains method, properties, and body of the delivered message. """ __slots__ = ('method', 'properties', 'body') def __init__(self, method, properties, body): """ :param spec.Basic.Deliver method: NOTE: consumer_tag and delivery_tag are valid only within source channel :param spec.BasicProperties properties: message properties :param bytes body: message body; empty string if no body """ self.method = method self.properties = properties self.body = body class _ConsumerCancellationEvt(_ChannelPendingEvt): """This event represents server-initiated consumer cancellation delivered to client via Basic.Cancel. After receiving Basic.Cancel, there will be no further deliveries for the consumer identified by `consumer_tag` in `Basic.Cancel` """ __slots__ = ('method_frame',) def __init__(self, method_frame): """ :param pika.frame.Method method_frame: method frame with method of type `spec.Basic.Cancel` """ self.method_frame = method_frame def __repr__(self): return '<%s method_frame=%r>' % (self.__class__.__name__, self.method_frame) @property def method(self): """method of type spec.Basic.Cancel""" return self.method_frame.method class _ReturnedMessageEvt(_ChannelPendingEvt): """This event represents a message returned by broker via `Basic.Return`""" __slots__ = ('callback', 'channel', 'method', 'properties', 'body') def __init__(self, callback, channel, method, properties, body): """ :param callable callback: user's callback, having the signature callback(channel, method, properties, body), where - channel: pika.Channel - method: pika.spec.Basic.Return - properties: pika.spec.BasicProperties - body: bytes :param pika.Channel channel: :param pika.spec.Basic.Return method: :param pika.spec.BasicProperties properties: :param bytes body: """ self.callback = callback self.channel = channel self.method = method self.properties = properties self.body = body def __repr__(self): return ('<%s callback=%r channel=%r method=%r properties=%r ' 'body=%.300r>') % (self.__class__.__name__, self.callback, self.channel, self.method, self.properties, self.body) def dispatch(self): """Dispatch user's callback""" self.callback(self.channel, self.method, self.properties, self.body) class ReturnedMessage(object): """Represents a message returned via Basic.Return in publish-acknowledgments mode """ __slots__ = ('method', 'properties', 'body') def __init__(self, method, properties, body): """ :param spec.Basic.Return method: :param spec.BasicProperties properties: message properties :param bytes body: message body; empty string if no body """ self.method = method self.properties = properties self.body = body class _ConsumerInfo(object): """Information about an active consumer""" __slots__ = ('consumer_tag', 'auto_ack', 'on_message_callback', 'alternate_event_sink', 'state') # Consumer states SETTING_UP = 1 ACTIVE = 2 TEARING_DOWN = 3 CANCELLED_BY_BROKER = 4 def __init__(self, consumer_tag, auto_ack, on_message_callback=None, alternate_event_sink=None): """ NOTE: exactly one of callback/alternate_event_sink musts be non-None. :param str consumer_tag: :param bool auto_ack: the no-ack value for the consumer :param callable on_message_callback: The function for dispatching messages to user, having the signature: on_message_callback(channel, method, properties, body) - channel: BlockingChannel - method: spec.Basic.Deliver - properties: spec.BasicProperties - body: bytes :param callable alternate_event_sink: if specified, _ConsumerDeliveryEvt and _ConsumerCancellationEvt objects will be diverted to this callback instead of being deposited in the channel's `_pending_events` container. Signature: alternate_event_sink(evt) """ assert (on_message_callback is None) != ( alternate_event_sink is None ), ('exactly one of on_message_callback/alternate_event_sink must be non-None', on_message_callback, alternate_event_sink) self.consumer_tag = consumer_tag self.auto_ack = auto_ack self.on_message_callback = on_message_callback self.alternate_event_sink = alternate_event_sink self.state = self.SETTING_UP @property def setting_up(self): """True if in SETTING_UP state""" return self.state == self.SETTING_UP @property def active(self): """True if in ACTIVE state""" return self.state == self.ACTIVE @property def tearing_down(self): """True if in TEARING_DOWN state""" return self.state == self.TEARING_DOWN @property def cancelled_by_broker(self): """True if in CANCELLED_BY_BROKER state""" return self.state == self.CANCELLED_BY_BROKER class _QueueConsumerGeneratorInfo(object): """Container for information about the active queue consumer generator """ __slots__ = ('params', 'consumer_tag', 'pending_events') def __init__(self, params, consumer_tag): """ :params tuple params: a three-tuple (queue, auto_ack, exclusive) that were used to create the queue consumer :param str consumer_tag: consumer tag """ self.params = params self.consumer_tag = consumer_tag #self.messages = deque() # Holds pending events of types _ConsumerDeliveryEvt and # _ConsumerCancellationEvt self.pending_events = deque() def __repr__(self): return '<%s params=%r consumer_tag=%r>' % ( self.__class__.__name__, self.params, self.consumer_tag) class BlockingChannel(object): """The BlockingChannel implements blocking semantics for most things that one would use callback-passing-style for with the :py:class:`~pika.channel.Channel` class. In addition, the `BlockingChannel` class implements a :term:`generator` that allows you to :doc:`consume messages ` without using callbacks. Example of creating a BlockingChannel:: import pika # Create our connection object connection = pika.BlockingConnection() # The returned object will be a synchronous channel channel = connection.channel() """ # Used as value_class with _CallbackResult for receiving Basic.GetOk args _RxMessageArgs = namedtuple( 'BlockingChannel__RxMessageArgs', [ 'channel', # implementation pika.Channel instance 'method', # Basic.GetOk 'properties', # pika.spec.BasicProperties 'body' # str, unicode, or bytes (python 3.x) ]) # For use as value_class with any _CallbackResult that expects method_frame # as the only arg _MethodFrameCallbackResultArgs = namedtuple( 'BlockingChannel__MethodFrameCallbackResultArgs', 'method_frame') # Broker's basic-ack/basic-nack args when delivery confirmation is enabled; # may concern a single or multiple messages _OnMessageConfirmationReportArgs = namedtuple( 'BlockingChannel__OnMessageConfirmationReportArgs', 'method_frame') # For use as value_class with _CallbackResult expecting Channel.Flow # confirmation. _FlowOkCallbackResultArgs = namedtuple( 'BlockingChannel__FlowOkCallbackResultArgs', 'active' # True if broker will start or continue sending; False if not ) _CONSUMER_CANCELLED_CB_KEY = 'blocking_channel_consumer_cancelled' def __init__(self, channel_impl, connection): """Create a new instance of the Channel :param pika.channel.Channel channel_impl: Channel implementation object as returned from SelectConnection.channel() :param BlockingConnection connection: The connection object """ self._impl = channel_impl self._connection = connection # A mapping of consumer tags to _ConsumerInfo for active consumers self._consumer_infos = dict() # Queue consumer generator generator info of type # _QueueConsumerGeneratorInfo created by BlockingChannel.consume self._queue_consumer_generator = None # Whether RabbitMQ delivery confirmation has been enabled self._delivery_confirmation = False # Receives message delivery confirmation report (Basic.ack or # Basic.nack) from broker when delivery confirmations are enabled self._message_confirmation_result = _CallbackResult( self._OnMessageConfirmationReportArgs) # deque of pending events: _ConsumerDeliveryEvt and # _ConsumerCancellationEvt objects that will be returned by # `BlockingChannel.get_event()` self._pending_events = deque() # Holds a ReturnedMessage object representing a message received via # Basic.Return in publisher-acknowledgments mode. self._puback_return = None # self._on_channel_closed() saves the reason exception here self._closing_reason = None # type: None | Exception # Receives Basic.ConsumeOk reply from server self._basic_consume_ok_result = _CallbackResult() # Receives args from Basic.GetEmpty response # http://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get self._basic_getempty_result = _CallbackResult( self._MethodFrameCallbackResultArgs) self._impl.add_on_cancel_callback(self._on_consumer_cancelled_by_broker) self._impl.add_callback( self._basic_consume_ok_result.signal_once, replies=[pika.spec.Basic.ConsumeOk], one_shot=False) self._impl.add_on_close_callback(self._on_channel_closed) self._impl.add_callback( self._basic_getempty_result.set_value_once, replies=[pika.spec.Basic.GetEmpty], one_shot=False) LOGGER.info("Created channel=%s", self.channel_number) def __int__(self): """Return the channel object as its channel number NOTE: inherited from legacy BlockingConnection; might be error-prone; use `channel_number` property instead. :rtype: int """ return self.channel_number def __repr__(self): return '<%s impl=%r>' % (self.__class__.__name__, self._impl) def __enter__(self): return self def __exit__(self, exc_type, value, traceback): if self.is_open: self.close() def _cleanup(self): """Clean up members that might inhibit garbage collection""" self._message_confirmation_result.reset() self._pending_events = deque() self._consumer_infos = dict() self._queue_consumer_generator = None @property def channel_number(self): """Channel number""" return self._impl.channel_number @property def connection(self): """The channel's BlockingConnection instance""" return self._connection @property def is_closed(self): """Returns True if the channel is closed. :rtype: bool """ return self._impl.is_closed @property def is_open(self): """Returns True if the channel is open. :rtype: bool """ return self._impl.is_open @property def consumer_tags(self): """Property method that returns a list of consumer tags for active consumers :rtype: list """ return compat.dictkeys(self._consumer_infos) _ALWAYS_READY_WAITERS = ((lambda: True),) def _flush_output(self, *waiters): """ Flush output and process input while waiting for any of the given callbacks to return true. The wait is aborted upon channel-close or connection-close. Otherwise, processing continues until the output is flushed AND at least one of the callbacks returns true. If there are no callbacks, then processing ends when all output is flushed. :param waiters: sequence of zero or more callables taking no args and returning true when it's time to stop processing. Their results are OR'ed together. An empty sequence is treated as equivalent to a waiter always returning true. """ if self.is_closed: self._impl._raise_if_not_open() if not waiters: waiters = self._ALWAYS_READY_WAITERS self._connection._flush_output(lambda: self.is_closed, *waiters) if self.is_closed and isinstance(self._closing_reason, exceptions.ChannelClosedByBroker): raise self._closing_reason # pylint: disable=E0702 def _on_puback_message_returned(self, channel, method, properties, body): """Called as the result of Basic.Return from broker in publisher-acknowledgements mode. Saves the info as a ReturnedMessage instance in self._puback_return. :param pika.Channel channel: our self._impl channel :param pika.spec.Basic.Return method: :param pika.spec.BasicProperties properties: message properties :param bytes body: returned message body; empty string if no body """ assert channel is self._impl, (channel.channel_number, self.channel_number) assert isinstance(method, pika.spec.Basic.Return), method assert isinstance(properties, pika.spec.BasicProperties), (properties) LOGGER.warning( "Published message was returned: _delivery_confirmation=%s; " "channel=%s; method=%r; properties=%r; body_size=%d; " "body_prefix=%.255r", self._delivery_confirmation, channel.channel_number, method, properties, len(body) if body is not None else None, body) self._puback_return = ReturnedMessage(method, properties, body) def _add_pending_event(self, evt): """Append an event to the channel's list of events that are ready for dispatch to user and signal our connection that this channel is ready for event dispatch :param _ChannelPendingEvt evt: an event derived from _ChannelPendingEvt """ self._pending_events.append(evt) self.connection._request_channel_dispatch(self.channel_number) def _on_channel_closed(self, _channel, reason): """Callback from impl notifying us that the channel has been closed. This may be as the result of user-, broker-, or internal connection clean-up initiated closing or meta-closing of the channel. If it resulted from receiving `Channel.Close` from broker, we will expedite waking up of the event subsystem so that it may respond by raising `ChannelClosed` from user's context. NOTE: We can't raise exceptions in callbacks in order to protect the integrity of the underlying implementation. BlockingConnection's underlying asynchronous connection adapter (SelectConnection) uses callbacks to communicate with us. If BlockingConnection leaks exceptions back into the I/O loop or the asynchronous connection adapter, we interrupt their normal workflow and introduce a high likelihood of state inconsistency. See `pika.Channel.add_on_close_callback()` for additional documentation. :param pika.Channel _channel: (unused) :param Exception reason: """ LOGGER.debug('_on_channel_closed: %r; %r', reason, self) self._closing_reason = reason if isinstance(reason, exceptions.ChannelClosedByBroker): self._cleanup() # Request urgent termination of `process_data_events()`, in case # it's executing or next time it will execute self.connection._request_channel_dispatch(-self.channel_number) def _on_consumer_cancelled_by_broker(self, method_frame): """Called by impl when broker cancels consumer via Basic.Cancel. This is a RabbitMQ-specific feature. The circumstances include deletion of queue being consumed as well as failure of a HA node responsible for the queue being consumed. :param pika.frame.Method method_frame: method frame with the `spec.Basic.Cancel` method """ evt = _ConsumerCancellationEvt(method_frame) consumer = self._consumer_infos[method_frame.method.consumer_tag] # Don't interfere with client-initiated cancellation flow if not consumer.tearing_down: consumer.state = _ConsumerInfo.CANCELLED_BY_BROKER if consumer.alternate_event_sink is not None: consumer.alternate_event_sink(evt) else: self._add_pending_event(evt) def _on_consumer_message_delivery(self, _channel, method, properties, body): """Called by impl when a message is delivered for a consumer :param Channel channel: The implementation channel object :param spec.Basic.Deliver method: :param pika.spec.BasicProperties properties: message properties :param bytes body: delivered message body; empty string if no body """ evt = _ConsumerDeliveryEvt(method, properties, body) consumer = self._consumer_infos[method.consumer_tag] if consumer.alternate_event_sink is not None: consumer.alternate_event_sink(evt) else: self._add_pending_event(evt) def _on_consumer_generator_event(self, evt): """Sink for the queue consumer generator's consumer events; append the event to queue consumer generator's pending events buffer. :param evt: an object of type _ConsumerDeliveryEvt or _ConsumerCancellationEvt """ self._queue_consumer_generator.pending_events.append(evt) # Schedule termination of connection.process_data_events using a # negative channel number self.connection._request_channel_dispatch(-self.channel_number) def _cancel_all_consumers(self): """Cancel all consumers. NOTE: pending non-ackable messages will be lost; pending ackable messages will be rejected. """ if self._consumer_infos: LOGGER.debug('Cancelling %i consumers', len(self._consumer_infos)) if self._queue_consumer_generator is not None: # Cancel queue consumer generator self.cancel() # Cancel consumers created via basic_consume for consumer_tag in compat.dictkeys(self._consumer_infos): self.basic_cancel(consumer_tag) def _dispatch_events(self): """Called by BlockingConnection to dispatch pending events. `BlockingChannel` schedules this callback via `BlockingConnection._request_channel_dispatch` """ while self._pending_events: evt = self._pending_events.popleft() if type(evt) is _ConsumerDeliveryEvt: # pylint: disable=C0123 consumer_info = self._consumer_infos[evt.method.consumer_tag] consumer_info.on_message_callback(self, evt.method, evt.properties, evt.body) elif type(evt) is _ConsumerCancellationEvt: # pylint: disable=C0123 del self._consumer_infos[evt.method_frame.method.consumer_tag] self._impl.callbacks.process(self.channel_number, self._CONSUMER_CANCELLED_CB_KEY, self, evt.method_frame) else: evt.dispatch() def close(self, reply_code=0, reply_text="Normal shutdown"): """Will invoke a clean shutdown of the channel with the AMQP Broker. :param int reply_code: The reply code to close the channel with :param str reply_text: The reply text to close the channel with """ LOGGER.debug('Channel.close(%s, %s)', reply_code, reply_text) self._impl._raise_if_not_open() try: # Cancel remaining consumers self._cancel_all_consumers() # Close the channel self._impl.close(reply_code=reply_code, reply_text=reply_text) self._flush_output(lambda: self.is_closed) finally: self._cleanup() def flow(self, active): """Turn Channel flow control off and on. NOTE: RabbitMQ doesn't support active=False; per https://www.rabbitmq.com/specification.html: "active=false is not supported by the server. Limiting prefetch with basic.qos provides much better control" For more information, please reference: http://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow :param bool active: Turn flow on (True) or off (False) :returns: True if broker will start or continue sending; False if not :rtype: bool """ with _CallbackResult(self._FlowOkCallbackResultArgs) as flow_ok_result: self._impl.flow( active=active, callback=flow_ok_result.set_value_once) self._flush_output(flow_ok_result.is_ready) return flow_ok_result.value.active def add_on_cancel_callback(self, callback): """Pass a callback function that will be called when Basic.Cancel is sent by the broker. The callback function should receive a method frame parameter. :param callable callback: a callable for handling broker's Basic.Cancel notification with the call signature: callback(method_frame) where method_frame is of type `pika.frame.Method` with method of type `spec.Basic.Cancel` """ self._impl.callbacks.add( self.channel_number, self._CONSUMER_CANCELLED_CB_KEY, callback, one_shot=False) def add_on_return_callback(self, callback): """Pass a callback function that will be called when a published message is rejected and returned by the server via `Basic.Return`. :param callable callback: The method to call on callback with the signature callback(channel, method, properties, body), where - channel: pika.Channel - method: pika.spec.Basic.Return - properties: pika.spec.BasicProperties - body: bytes """ self._impl.add_on_return_callback( lambda _channel, method, properties, body: ( self._add_pending_event( _ReturnedMessageEvt( callback, self, method, properties, body)))) def basic_consume(self, queue, on_message_callback, auto_ack=False, exclusive=False, consumer_tag=None, arguments=None): """Sends the AMQP command Basic.Consume to the broker and binds messages for the consumer_tag to the consumer callback. If you do not pass in a consumer_tag, one will be automatically generated for you. Returns the consumer tag. NOTE: the consumer callbacks are dispatched only in the scope of specially-designated methods: see `BlockingConnection.process_data_events` and `BlockingChannel.start_consuming`. For more information about Basic.Consume, see: http://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume :param str queue: The queue from which to consume :param callable on_message_callback: Required function for dispatching messages to user, having the signature: on_message_callback(channel, method, properties, body) - channel: BlockingChannel - method: spec.Basic.Deliver - properties: spec.BasicProperties - body: bytes :param bool auto_ack: if set to True, automatic acknowledgement mode will be used (see http://www.rabbitmq.com/confirms.html). This corresponds with the 'no_ack' parameter in the basic.consume AMQP 0.9.1 method :param bool exclusive: Don't allow other consumers on the queue :param str consumer_tag: You may specify your own consumer tag; if left empty, a consumer tag will be generated automatically :param dict arguments: Custom key/value pair arguments for the consumer :returns: consumer tag :rtype: str :raises pika.exceptions.DuplicateConsumerTag: if consumer with given consumer_tag is already present. """ validators.require_string(queue, 'queue') validators.require_callback(on_message_callback, 'on_message_callback') return self._basic_consume_impl( queue=queue, on_message_callback=on_message_callback, auto_ack=auto_ack, exclusive=exclusive, consumer_tag=consumer_tag, arguments=arguments) def _basic_consume_impl(self, queue, auto_ack, exclusive, consumer_tag, arguments=None, on_message_callback=None, alternate_event_sink=None): """The low-level implementation used by `basic_consume` and `consume`. See `basic_consume` docstring for more info. NOTE: exactly one of on_message_callback/alternate_event_sink musts be non-None. This method has one additional parameter alternate_event_sink over the args described in `basic_consume`. :param callable alternate_event_sink: if specified, _ConsumerDeliveryEvt and _ConsumerCancellationEvt objects will be diverted to this callback instead of being deposited in the channel's `_pending_events` container. Signature: alternate_event_sink(evt) :raises pika.exceptions.DuplicateConsumerTag: if consumer with given consumer_tag is already present. """ if (on_message_callback is None) == (alternate_event_sink is None): raise ValueError( ('exactly one of on_message_callback/alternate_event_sink must ' 'be non-None', on_message_callback, alternate_event_sink)) if not consumer_tag: # Need a consumer tag to register consumer info before sending # request to broker, because I/O might dispatch incoming messages # immediately following Basic.Consume-ok before _flush_output # returns consumer_tag = self._impl._generate_consumer_tag() if consumer_tag in self._consumer_infos: raise exceptions.DuplicateConsumerTag(consumer_tag) # Create new consumer self._consumer_infos[consumer_tag] = _ConsumerInfo( consumer_tag, auto_ack=auto_ack, on_message_callback=on_message_callback, alternate_event_sink=alternate_event_sink) try: with self._basic_consume_ok_result as ok_result: tag = self._impl.basic_consume( on_message_callback=self._on_consumer_message_delivery, queue=queue, auto_ack=auto_ack, exclusive=exclusive, consumer_tag=consumer_tag, arguments=arguments) assert tag == consumer_tag, (tag, consumer_tag) self._flush_output(ok_result.is_ready) except Exception: # If channel was closed, self._consumer_infos will be empty if consumer_tag in self._consumer_infos: del self._consumer_infos[consumer_tag] # Schedule termination of connection.process_data_events using a # negative channel number self.connection._request_channel_dispatch(-self.channel_number) raise # NOTE: Consumer could get cancelled by broker immediately after opening # (e.g., queue getting deleted externally) if self._consumer_infos[consumer_tag].setting_up: self._consumer_infos[consumer_tag].state = _ConsumerInfo.ACTIVE return consumer_tag def basic_cancel(self, consumer_tag): """This method cancels a consumer. This does not affect already delivered messages, but it does mean the server will not send any more messages for that consumer. The client may receive an arbitrary number of messages in between sending the cancel method and receiving the cancel-ok reply. NOTE: When cancelling an auto_ack=False consumer, this implementation automatically Nacks and suppresses any incoming messages that have not yet been dispatched to the consumer's callback. However, when cancelling a auto_ack=True consumer, this method will return any pending messages that arrived before broker confirmed the cancellation. :param str consumer_tag: Identifier for the consumer; the result of passing a consumer_tag that was created on another channel is undefined (bad things will happen) :returns: (NEW IN pika 0.10.0) empty sequence for a auto_ack=False consumer; for a auto_ack=True consumer, returns a (possibly empty) sequence of pending messages that arrived before broker confirmed the cancellation (this is done instead of via consumer's callback in order to prevent reentrancy/recursion. Each message is four-tuple: (channel, method, properties, body) - channel: BlockingChannel - method: spec.Basic.Deliver - properties: spec.BasicProperties - body: bytes :rtype: list """ try: consumer_info = self._consumer_infos[consumer_tag] except KeyError: LOGGER.warning( "User is attempting to cancel an unknown consumer=%s; " "already cancelled by user or broker?", consumer_tag) return [] try: # Assertion failure here is most likely due to reentrance assert consumer_info.active or consumer_info.cancelled_by_broker, ( consumer_info.state) # Assertion failure here signals disconnect between consumer state # in BlockingChannel and Channel assert (consumer_info.cancelled_by_broker or consumer_tag in self._impl._consumers), consumer_tag auto_ack = consumer_info.auto_ack consumer_info.state = _ConsumerInfo.TEARING_DOWN with _CallbackResult() as cancel_ok_result: # Nack pending messages for auto_ack=False consumer if not auto_ack: pending_messages = self._remove_pending_deliveries( consumer_tag) if pending_messages: # NOTE: we use impl's basic_reject to avoid the # possibility of redelivery before basic_cancel takes # control of nacking. # NOTE: we can't use basic_nack with the multiple option # to avoid nacking messages already held by our client. for message in pending_messages: self._impl.basic_reject( message.method.delivery_tag, requeue=True) # Cancel the consumer; impl takes care of rejecting any # additional deliveries that arrive for a auto_ack=False # consumer self._impl.basic_cancel( consumer_tag=consumer_tag, callback=cancel_ok_result.signal_once) # Flush output and wait for Basic.Cancel-ok or # broker-initiated Basic.Cancel self._flush_output( cancel_ok_result.is_ready, lambda: consumer_tag not in self._impl._consumers) if auto_ack: # Return pending messages for auto_ack=True consumer return [(evt.method, evt.properties, evt.body) for evt in self._remove_pending_deliveries(consumer_tag) ] else: # impl takes care of rejecting any incoming deliveries during # cancellation messages = self._remove_pending_deliveries(consumer_tag) assert not messages, messages return [] finally: # NOTE: The entry could be purged if channel or connection closes if consumer_tag in self._consumer_infos: del self._consumer_infos[consumer_tag] # Schedule termination of connection.process_data_events using a # negative channel number self.connection._request_channel_dispatch(-self.channel_number) def _remove_pending_deliveries(self, consumer_tag): """Extract _ConsumerDeliveryEvt objects destined for the given consumer from pending events, discarding the _ConsumerCancellationEvt, if any :param str consumer_tag: :returns: a (possibly empty) sequence of _ConsumerDeliveryEvt destined for the given consumer tag :rtype: list """ remaining_events = deque() unprocessed_messages = [] while self._pending_events: evt = self._pending_events.popleft() if type(evt) is _ConsumerDeliveryEvt: # pylint: disable=C0123 if evt.method.consumer_tag == consumer_tag: unprocessed_messages.append(evt) continue if type(evt) is _ConsumerCancellationEvt: # pylint: disable=C0123 if evt.method_frame.method.consumer_tag == consumer_tag: # A broker-initiated Basic.Cancel must have arrived # before our cancel request completed continue remaining_events.append(evt) self._pending_events = remaining_events return unprocessed_messages def start_consuming(self): """Processes I/O events and dispatches timers and `basic_consume` callbacks until all consumers are cancelled. NOTE: this blocking function may not be called from the scope of a pika callback, because dispatching `basic_consume` callbacks from this context would constitute recursion. :raises pika.exceptions.ReentrancyError: if called from the scope of a `BlockingConnection` or `BlockingChannel` callback :raises ChannelClosed: when this channel is closed by broker. """ # Check if called from the scope of an event dispatch callback with self.connection._acquire_event_dispatch() as dispatch_allowed: if not dispatch_allowed: raise exceptions.ReentrancyError( 'start_consuming may not be called from the scope of ' 'another BlockingConnection or BlockingChannel callback') self._impl._raise_if_not_open() # Process events as long as consumers exist on this channel while self._consumer_infos: # This will raise ChannelClosed if channel is closed by broker self._process_data_events(time_limit=None) def stop_consuming(self, consumer_tag=None): """ Cancels all consumers, signalling the `start_consuming` loop to exit. NOTE: pending non-ackable messages will be lost; pending ackable messages will be rejected. """ if consumer_tag: self.basic_cancel(consumer_tag) else: self._cancel_all_consumers() def consume(self, queue, auto_ack=False, exclusive=False, arguments=None, inactivity_timeout=None): """Blocking consumption of a queue instead of via a callback. This method is a generator that yields each message as a tuple of method, properties, and body. The active generator iterator terminates when the consumer is cancelled by client via `BlockingChannel.cancel()` or by broker. Example: :: for method, properties, body in channel.consume('queue'): print(body) channel.basic_ack(method.delivery_tag) You should call `BlockingChannel.cancel()` when you escape out of the generator loop. If you don't cancel this consumer, then next call on the same channel to `consume()` with the exact same (queue, auto_ack, exclusive) parameters will resume the existing consumer generator; however, calling with different parameters will result in an exception. :param str queue: The queue name to consume :param bool auto_ack: Tell the broker to not expect a ack/nack response :param bool exclusive: Don't allow other consumers on the queue :param dict arguments: Custom key/value pair arguments for the consumer :param float inactivity_timeout: if a number is given (in seconds), will cause the method to yield (None, None, None) after the given period of inactivity; this permits for pseudo-regular maintenance activities to be carried out by the user while waiting for messages to arrive. If None is given (default), then the method blocks until the next event arrives. NOTE that timing granularity is limited by the timer resolution of the underlying implementation. NEW in pika 0.10.0. :yields: tuple(spec.Basic.Deliver, spec.BasicProperties, str or unicode) :raises ValueError: if consumer-creation parameters don't match those of the existing queue consumer generator, if any. NEW in pika 0.10.0 :raises ChannelClosed: when this channel is closed by broker. """ self._impl._raise_if_not_open() params = (queue, auto_ack, exclusive) if self._queue_consumer_generator is not None: if params != self._queue_consumer_generator.params: raise ValueError( 'Consume with different params not allowed on existing ' 'queue consumer generator; previous params: %r; ' 'new params: %r' % (self._queue_consumer_generator.params, (queue, auto_ack, exclusive))) else: LOGGER.debug('Creating new queue consumer generator; params: %r', params) # Need a consumer tag to register consumer info before sending # request to broker, because I/O might pick up incoming messages # in addition to Basic.Consume-ok consumer_tag = self._impl._generate_consumer_tag() self._queue_consumer_generator = _QueueConsumerGeneratorInfo( params, consumer_tag) try: self._basic_consume_impl( queue=queue, auto_ack=auto_ack, exclusive=exclusive, consumer_tag=consumer_tag, arguments=arguments, alternate_event_sink=self._on_consumer_generator_event) except Exception: self._queue_consumer_generator = None raise LOGGER.info('Created new queue consumer generator %r', self._queue_consumer_generator) while self._queue_consumer_generator is not None: # Process pending events if self._queue_consumer_generator.pending_events: evt = self._queue_consumer_generator.pending_events.popleft() if type(evt) is _ConsumerCancellationEvt: # pylint: disable=C0123 # Consumer was cancelled by broker self._queue_consumer_generator = None break else: yield (evt.method, evt.properties, evt.body) continue if inactivity_timeout is None: # Wait indefinitely for a message to arrive, while processing # I/O events and triggering ChannelClosed exception when the # channel fails self._process_data_events(time_limit=None) continue # Wait with inactivity timeout wait_start_time = compat.time_now() wait_deadline = wait_start_time + inactivity_timeout delta = inactivity_timeout while (self._queue_consumer_generator is not None and not self._queue_consumer_generator.pending_events): self._process_data_events(time_limit=delta) if not self._queue_consumer_generator: # Consumer was cancelled by client break if self._queue_consumer_generator.pending_events: # Got message(s) break delta = wait_deadline - compat.time_now() if delta <= 0.0: # Signal inactivity timeout yield (None, None, None) break def _process_data_events(self, time_limit): """Wrapper for `BlockingConnection.process_data_events()` with common channel-specific logic that raises ChannelClosed if broker closed this channel. NOTE: We need to raise an exception in the context of user's call into our API to protect the integrity of the underlying implementation. BlockingConnection's underlying asynchronous connection adapter (SelectConnection) uses callbacks to communicate with us. If BlockingConnection leaks exceptions back into the I/O loop or the asynchronous connection adapter, we interrupt their normal workflow and introduce a high likelihood of state inconsistency. See `BlockingConnection.process_data_events()` for documentation of args and behavior. :param float time_limit: """ self.connection.process_data_events(time_limit=time_limit) if self.is_closed and isinstance(self._closing_reason, exceptions.ChannelClosedByBroker): LOGGER.debug('Channel close by broker detected, raising %r; %r', self._closing_reason, self) raise self._closing_reason # pylint: disable=E0702 def get_waiting_message_count(self): """Returns the number of messages that may be retrieved from the current queue consumer generator via `BlockingChannel.consume` without blocking. NEW in pika 0.10.0 :returns: The number of waiting messages :rtype: int """ if self._queue_consumer_generator is not None: pending_events = self._queue_consumer_generator.pending_events count = len(pending_events) if count and type(pending_events[-1]) is _ConsumerCancellationEvt: # pylint: disable=C0123 count -= 1 else: count = 0 return count def cancel(self): """Cancel the queue consumer created by `BlockingChannel.consume`, rejecting all pending ackable messages. NOTE: If you're looking to cancel a consumer issued with BlockingChannel.basic_consume then you should call BlockingChannel.basic_cancel. :returns: The number of messages requeued by Basic.Nack. NEW in 0.10.0: returns 0 :rtype: int """ if self._queue_consumer_generator is None: LOGGER.warning('cancel: queue consumer generator is inactive ' '(already cancelled by client or broker?)') return 0 try: _, auto_ack, _ = self._queue_consumer_generator.params if not auto_ack: # Reject messages held by queue consumer generator; NOTE: we # can't use basic_nack with the multiple option to avoid nacking # messages already held by our client. pending_events = self._queue_consumer_generator.pending_events # NOTE `get_waiting_message_count` adjusts for `Basic.Cancel` # from the server at the end (if any) for _ in compat.xrange(self.get_waiting_message_count()): evt = pending_events.popleft() self._impl.basic_reject( evt.method.delivery_tag, requeue=True) self.basic_cancel(self._queue_consumer_generator.consumer_tag) finally: self._queue_consumer_generator = None # Return 0 for compatibility with legacy implementation; the number of # nacked messages is not meaningful since only messages consumed with # auto_ack=False may be nacked, and those arriving after calling # basic_cancel will be rejected automatically by impl channel, so we'll # never know how many of those were nacked. return 0 def basic_ack(self, delivery_tag=0, multiple=False): """Acknowledge one or more messages. When sent by the client, this method acknowledges one or more messages delivered via the Deliver or Get-Ok methods. When sent by server, this method acknowledges one or more messages published with the Publish method on a channel in confirm mode. The acknowledgement can be for a single message or a set of messages up to and including a specific message. :param int delivery_tag: The server-assigned delivery tag :param bool multiple: If set to True, the delivery tag is treated as "up to and including", so that multiple messages can be acknowledged with a single method. If set to False, the delivery tag refers to a single message. If the multiple field is 1, and the delivery tag is zero, this indicates acknowledgement of all outstanding messages. """ self._impl.basic_ack(delivery_tag=delivery_tag, multiple=multiple) self._flush_output() def basic_nack(self, delivery_tag=0, multiple=False, requeue=True): """This method allows a client to reject one or more incoming messages. It can be used to interrupt and cancel large incoming messages, or return untreatable messages to their original queue. :param int delivery_tag: The server-assigned delivery tag :param bool multiple: If set to True, the delivery tag is treated as "up to and including", so that multiple messages can be acknowledged with a single method. If set to False, the delivery tag refers to a single message. If the multiple field is 1, and the delivery tag is zero, this indicates acknowledgement of all outstanding messages. :param bool requeue: If requeue is true, the server will attempt to requeue the message. If requeue is false or the requeue attempt fails the messages are discarded or dead-lettered. """ self._impl.basic_nack( delivery_tag=delivery_tag, multiple=multiple, requeue=requeue) self._flush_output() def basic_get(self, queue, auto_ack=False): """Get a single message from the AMQP broker. Returns a sequence with the method frame, message properties, and body. :param str queue: Name of queue from which to get a message :param bool auto_ack: Tell the broker to not expect a reply :returns: a three-tuple; (None, None, None) if the queue was empty; otherwise (method, properties, body); NOTE: body may be None :rtype: (spec.Basic.GetOk|None, spec.BasicProperties|None, bytes|None) """ assert not self._basic_getempty_result validators.require_string(queue, 'queue') # NOTE: nested with for python 2.6 compatibility with _CallbackResult(self._RxMessageArgs) as get_ok_result: with self._basic_getempty_result: self._impl.basic_get( queue=queue, auto_ack=auto_ack, callback=get_ok_result.set_value_once) self._flush_output(get_ok_result.is_ready, self._basic_getempty_result.is_ready) if get_ok_result: evt = get_ok_result.value return evt.method, evt.properties, evt.body else: assert self._basic_getempty_result, ( "wait completed without GetOk and GetEmpty") return None, None, None def basic_publish(self, exchange, routing_key, body, properties=None, mandatory=False): """Publish to the channel with the given exchange, routing key, and body. For more information on basic_publish and what the parameters do, see: http://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.publish NOTE: mandatory may be enabled even without delivery confirmation, but in the absence of delivery confirmation the synchronous implementation has no way to know how long to wait for the Basic.Return. :param str exchange: The exchange to publish to :param str routing_key: The routing key to bind on :param bytes body: The message body; empty string if no body :param pika.spec.BasicProperties properties: message properties :param bool mandatory: The mandatory flag :raises UnroutableError: raised when a message published in publisher-acknowledgments mode (see `BlockingChannel.confirm_delivery`) is returned via `Basic.Return` followed by `Basic.Ack`. :raises NackError: raised when a message published in publisher-acknowledgements mode is Nack'ed by the broker. See `BlockingChannel.confirm_delivery`. """ if self._delivery_confirmation: # In publisher-acknowledgments mode with self._message_confirmation_result: self._impl.basic_publish( exchange=exchange, routing_key=routing_key, body=body, properties=properties, mandatory=mandatory) self._flush_output(self._message_confirmation_result.is_ready) conf_method = ( self._message_confirmation_result.value.method_frame.method) if isinstance(conf_method, pika.spec.Basic.Nack): # Broker was unable to process the message due to internal # error LOGGER.warning( "Message was Nack'ed by broker: nack=%r; channel=%s; " "exchange=%s; routing_key=%s; mandatory=%r; ", conf_method, self.channel_number, exchange, routing_key, mandatory) if self._puback_return is not None: returned_messages = [self._puback_return] self._puback_return = None else: returned_messages = [] raise exceptions.NackError(returned_messages) else: assert isinstance(conf_method, pika.spec.Basic.Ack), (conf_method) if self._puback_return is not None: # Unroutable message was returned messages = [self._puback_return] self._puback_return = None raise exceptions.UnroutableError(messages) else: # In non-publisher-acknowledgments mode self._impl.basic_publish( exchange=exchange, routing_key=routing_key, body=body, properties=properties, mandatory=mandatory) self._flush_output() def basic_qos(self, prefetch_size=0, prefetch_count=0, global_qos=False): """Specify quality of service. This method requests a specific quality of service. The QoS can be specified for the current channel or for all channels on the connection. The client can request that messages be sent in advance so that when the client finishes processing a message, the following message is already held locally, rather than needing to be sent down the channel. Prefetching gives a performance improvement. :param int prefetch_size: This field specifies the prefetch window size. The server will send a message in advance if it is equal to or smaller in size than the available prefetch size (and also falls into other prefetch limits). May be set to zero, meaning "no specific limit", although other prefetch limits may still apply. The prefetch-size is ignored if the no-ack option is set in the consumer. :param int prefetch_count: Specifies a prefetch window in terms of whole messages. This field may be used in combination with the prefetch-size field; a message will only be sent in advance if both prefetch windows (and those at the channel and connection level) allow it. The prefetch-count is ignored if the no-ack option is set in the consumer. :param bool global_qos: Should the QoS apply to all channels on the connection. """ with _CallbackResult() as qos_ok_result: self._impl.basic_qos( callback=qos_ok_result.signal_once, prefetch_size=prefetch_size, prefetch_count=prefetch_count, global_qos=global_qos) self._flush_output(qos_ok_result.is_ready) def basic_recover(self, requeue=False): """This method asks the server to redeliver all unacknowledged messages on a specified channel. Zero or more messages may be redelivered. This method replaces the asynchronous Recover. :param bool requeue: If False, the message will be redelivered to the original recipient. If True, the server will attempt to requeue the message, potentially then delivering it to an alternative subscriber. """ with _CallbackResult() as recover_ok_result: self._impl.basic_recover( requeue=requeue, callback=recover_ok_result.signal_once) self._flush_output(recover_ok_result.is_ready) def basic_reject(self, delivery_tag=0, requeue=True): """Reject an incoming message. This method allows a client to reject a message. It can be used to interrupt and cancel large incoming messages, or return untreatable messages to their original queue. :param int delivery_tag: The server-assigned delivery tag :param bool requeue: If requeue is true, the server will attempt to requeue the message. If requeue is false or the requeue attempt fails the messages are discarded or dead-lettered. """ self._impl.basic_reject(delivery_tag=delivery_tag, requeue=requeue) self._flush_output() def confirm_delivery(self): """Turn on RabbitMQ-proprietary Confirm mode in the channel. For more information see: https://www.rabbitmq.com/confirms.html """ if self._delivery_confirmation: LOGGER.error( 'confirm_delivery: confirmation was already enabled ' 'on channel=%s', self.channel_number) return with _CallbackResult() as select_ok_result: self._impl.confirm_delivery( ack_nack_callback=self._message_confirmation_result. set_value_once, callback=select_ok_result.signal_once) self._flush_output(select_ok_result.is_ready) self._delivery_confirmation = True # Unroutable messages returned after this point will be in the context # of publisher acknowledgments self._impl.add_on_return_callback(self._on_puback_message_returned) def exchange_declare(self, exchange, exchange_type=ExchangeType.direct, passive=False, durable=False, auto_delete=False, internal=False, arguments=None): """This method creates an exchange if it does not already exist, and if the exchange exists, verifies that it is of the correct and expected class. If passive set, the server will reply with Declare-Ok if the exchange already exists with the same name, and raise an error if not and if the exchange does not already exist, the server MUST raise a channel exception with reply code 404 (not found). :param str exchange: The exchange name consists of a non-empty sequence of these characters: letters, digits, hyphen, underscore, period, or colon. :param str exchange_type: The exchange type to use :param bool passive: Perform a declare or just check to see if it exists :param bool durable: Survive a reboot of RabbitMQ :param bool auto_delete: Remove when no more queues are bound to it :param bool internal: Can only be published to by other exchanges :param dict arguments: Custom key/value pair arguments for the exchange :returns: Method frame from the Exchange.Declare-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Exchange.DeclareOk` """ validators.require_string(exchange, 'exchange') with _CallbackResult( self._MethodFrameCallbackResultArgs) as declare_ok_result: self._impl.exchange_declare( exchange=exchange, exchange_type=exchange_type, passive=passive, durable=durable, auto_delete=auto_delete, internal=internal, arguments=arguments, callback=declare_ok_result.set_value_once) self._flush_output(declare_ok_result.is_ready) return declare_ok_result.value.method_frame def exchange_delete(self, exchange=None, if_unused=False): """Delete the exchange. :param str exchange: The exchange name :param bool if_unused: only delete if the exchange is unused :returns: Method frame from the Exchange.Delete-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Exchange.DeleteOk` """ with _CallbackResult( self._MethodFrameCallbackResultArgs) as delete_ok_result: self._impl.exchange_delete( exchange=exchange, if_unused=if_unused, callback=delete_ok_result.set_value_once) self._flush_output(delete_ok_result.is_ready) return delete_ok_result.value.method_frame def exchange_bind(self, destination, source, routing_key='', arguments=None): """Bind an exchange to another exchange. :param str destination: The destination exchange to bind :param str source: The source exchange to bind to :param str routing_key: The routing key to bind on :param dict arguments: Custom key/value pair arguments for the binding :returns: Method frame from the Exchange.Bind-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Exchange.BindOk` """ validators.require_string(destination, 'destination') validators.require_string(source, 'source') with _CallbackResult(self._MethodFrameCallbackResultArgs) as \ bind_ok_result: self._impl.exchange_bind( destination=destination, source=source, routing_key=routing_key, arguments=arguments, callback=bind_ok_result.set_value_once) self._flush_output(bind_ok_result.is_ready) return bind_ok_result.value.method_frame def exchange_unbind(self, destination=None, source=None, routing_key='', arguments=None): """Unbind an exchange from another exchange. :param str destination: The destination exchange to unbind :param str source: The source exchange to unbind from :param str routing_key: The routing key to unbind :param dict arguments: Custom key/value pair arguments for the binding :returns: Method frame from the Exchange.Unbind-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Exchange.UnbindOk` """ with _CallbackResult( self._MethodFrameCallbackResultArgs) as unbind_ok_result: self._impl.exchange_unbind( destination=destination, source=source, routing_key=routing_key, arguments=arguments, callback=unbind_ok_result.set_value_once) self._flush_output(unbind_ok_result.is_ready) return unbind_ok_result.value.method_frame def queue_declare(self, queue, passive=False, durable=False, exclusive=False, auto_delete=False, arguments=None): """Declare queue, create if needed. This method creates or checks a queue. When creating a new queue the client can specify various properties that control the durability of the queue and its contents, and the level of sharing for the queue. Use an empty string as the queue name for the broker to auto-generate one. Retrieve this auto-generated queue name from the returned `spec.Queue.DeclareOk` method frame. :param str queue: The queue name; if empty string, the broker will create a unique queue name :param bool passive: Only check to see if the queue exists and raise `ChannelClosed` if it doesn't :param bool durable: Survive reboots of the broker :param bool exclusive: Only allow access by the current connection :param bool auto_delete: Delete after consumer cancels or disconnects :param dict arguments: Custom key/value arguments for the queue :returns: Method frame from the Queue.Declare-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Queue.DeclareOk` """ validators.require_string(queue, 'queue') with _CallbackResult(self._MethodFrameCallbackResultArgs) as \ declare_ok_result: self._impl.queue_declare( queue=queue, passive=passive, durable=durable, exclusive=exclusive, auto_delete=auto_delete, arguments=arguments, callback=declare_ok_result.set_value_once) self._flush_output(declare_ok_result.is_ready) return declare_ok_result.value.method_frame def queue_delete(self, queue, if_unused=False, if_empty=False): """Delete a queue from the broker. :param str queue: The queue to delete :param bool if_unused: only delete if it's unused :param bool if_empty: only delete if the queue is empty :returns: Method frame from the Queue.Delete-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Queue.DeleteOk` """ with _CallbackResult(self._MethodFrameCallbackResultArgs) as \ delete_ok_result: self._impl.queue_delete( queue=queue, if_unused=if_unused, if_empty=if_empty, callback=delete_ok_result.set_value_once) self._flush_output(delete_ok_result.is_ready) return delete_ok_result.value.method_frame def queue_purge(self, queue): """Purge all of the messages from the specified queue :param str queue: The queue to purge :returns: Method frame from the Queue.Purge-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Queue.PurgeOk` """ with _CallbackResult(self._MethodFrameCallbackResultArgs) as \ purge_ok_result: self._impl.queue_purge( queue=queue, callback=purge_ok_result.set_value_once) self._flush_output(purge_ok_result.is_ready) return purge_ok_result.value.method_frame def queue_bind(self, queue, exchange, routing_key=None, arguments=None): """Bind the queue to the specified exchange :param str queue: The queue to bind to the exchange :param str exchange: The source exchange to bind to :param str routing_key: The routing key to bind on :param dict arguments: Custom key/value pair arguments for the binding :returns: Method frame from the Queue.Bind-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Queue.BindOk` """ validators.require_string(queue, 'queue') validators.require_string(exchange, 'exchange') with _CallbackResult( self._MethodFrameCallbackResultArgs) as bind_ok_result: self._impl.queue_bind( queue=queue, exchange=exchange, routing_key=routing_key, arguments=arguments, callback=bind_ok_result.set_value_once) self._flush_output(bind_ok_result.is_ready) return bind_ok_result.value.method_frame def queue_unbind(self, queue, exchange=None, routing_key=None, arguments=None): """Unbind a queue from an exchange. :param str queue: The queue to unbind from the exchange :param str exchange: The source exchange to bind from :param str routing_key: The routing key to unbind :param dict arguments: Custom key/value pair arguments for the binding :returns: Method frame from the Queue.Unbind-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Queue.UnbindOk` """ with _CallbackResult(self._MethodFrameCallbackResultArgs) as \ unbind_ok_result: self._impl.queue_unbind( queue=queue, exchange=exchange, routing_key=routing_key, arguments=arguments, callback=unbind_ok_result.set_value_once) self._flush_output(unbind_ok_result.is_ready) return unbind_ok_result.value.method_frame def tx_select(self): """Select standard transaction mode. This method sets the channel to use standard transactions. The client must use this method at least once on a channel before using the Commit or Rollback methods. :returns: Method frame from the Tx.Select-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Tx.SelectOk` """ with _CallbackResult(self._MethodFrameCallbackResultArgs) as \ select_ok_result: self._impl.tx_select(select_ok_result.set_value_once) self._flush_output(select_ok_result.is_ready) return select_ok_result.value.method_frame def tx_commit(self): """Commit a transaction. :returns: Method frame from the Tx.Commit-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Tx.CommitOk` """ with _CallbackResult(self._MethodFrameCallbackResultArgs) as \ commit_ok_result: self._impl.tx_commit(commit_ok_result.set_value_once) self._flush_output(commit_ok_result.is_ready) return commit_ok_result.value.method_frame def tx_rollback(self): """Rollback a transaction. :returns: Method frame from the Tx.Commit-ok response :rtype: `pika.frame.Method` having `method` attribute of type `spec.Tx.CommitOk` """ with _CallbackResult(self._MethodFrameCallbackResultArgs) as \ rollback_ok_result: self._impl.tx_rollback(rollback_ok_result.set_value_once) self._flush_output(rollback_ok_result.is_ready) return rollback_ok_result.value.method_frame