# ***** BEGIN LICENSE BLOCK ***** # # For copyright and licensing please refer to COPYING. # # ***** END LICENSE BLOCK ***** import types from warnings import warn import pika.channel as channel import pika.credentials import pika.frame import pika.log import pika.simplebuffer as simplebuffer import pika.spec as spec from pika.callback import CallbackManager from pika.exceptions import * from pika.heartbeat import HeartbeatChecker from pika.reconnection_strategies import NullReconnectionStrategy PRODUCT = "Pika Python AMQP Client Library" class ConnectionParameters(object): """ Connection parameters object that is passed into the connection adapter upon construction. The following parameters are passed and are used to negotiate communication with RabbitMQ: - host: Hostname or IP Address to connect to, defaults to localhost. - port: TCP port to connect to, defaults to 5672 - virtual_host: RabbitMQ virtual host to use, defaults to / - credentials: A instance of a credentials class to authenticate with. Defaults to PlainCredentials for the guest user. - channel_max: Maximum number of channels to allow, defaults to 0 for None - frame_max: The maximum byte size for an AMQP frame. Defaults to 131072 - heartbeat: Turn heartbeat checking on or off. Defaults to False. """ def __init__(self, host='localhost', port=spec.PORT, virtual_host='/', credentials=None, channel_max=0, frame_max=spec.FRAME_MAX_SIZE, heartbeat=False): # Validate the host type if not isinstance(host, str): raise TypeError("Host must be a str") # Validate the port coming in if not isinstance(port, int): raise TypeError("Port must be an int") # Define the default credentials if not credentials: credentials = pika.credentials.PlainCredentials('guest', 'guest') # Validate that the credentials are our supported type else: # Loop through the credential types in the credentials module valid_types = [] for credential_type in pika.credentials.VALID_TYPES: # Found a valid credential type if isinstance(credentials, credential_type): valid_types = None break else: valid_types.append(credentials.__class__.__name__) # Allow for someone to extend VALID_TYPES with custom types if valid_types: if len(pika.credentials.VALID_TYPES) > 1: message = 'credentials must be an object of type: %s' % \ ', '.join(valid_types) else: message = 'credentials must be an instance of %s' % \ valid_types[0] raise TypeError(message) if not isinstance(channel_max, int): raise TypeError("max-channels must be an int") # Validate the frame_max type coming in if not isinstance(frame_max, int): raise TypeError("frame_max must be an int") # Validate the FRAME_MAX isn't less than min frame size if frame_max < spec.FRAME_MIN_SIZE: raise InvalidFrameSize("AMQP Minimum Frame Size is %i Bytes" % \ spec.FRAME_MIN_SIZE) # Validate the frame_max isn't greater than the max frame size elif frame_max > spec.FRAME_MAX_SIZE: raise InvalidFrameSize("AMQP Maximum Frame Size is %i Bytes" % \ spec.FRAME_MAX_SIZE) # Validate the frame_max type coming in if not isinstance(frame_max, int): raise TypeError("frame_max must be an int") # Validate the heartbeat parameter: if not isinstance(heartbeat, bool): raise TypeError("heartbeat must be a bool") # Assign our values self.host = host self.port = port self.virtual_host = virtual_host self.credentials = credentials self.channel_max = channel_max self.frame_max = frame_max self.heartbeat = int(heartbeat) class Connection(object): """ Pika Connection Class This is the core class that implements communication with RabbitMQ. This class should not be invoked directly but rather through the use of an adapter such as SelectConnection or BlockingConnection. """ def __init__(self, parameters=None, on_open_callback=None, reconnection_strategy=None): """ Connection initialization expects a ConnectionParameters object and a callback function to notify when we have successfully connected to the AMQP Broker. A reconnection_strategy of None will use the NullReconnectionStrategy """ self._buffer = '' # Define our callback dictionary self.callbacks = CallbackManager() # On connection callback if on_open_callback: self.add_on_open_callback(on_open_callback) # Set our configuration options self.parameters = parameters or ConnectionParameters() # If we did not pass in a reconnection_strategy, setup the default self.reconnection = reconnection_strategy or NullReconnectionStrategy() # Validate that we don't have erase_credentials enabled with a non # Null reconnection strategy if self.parameters.credentials.erase_on_connect and \ not isinstance(self.reconnection, NullReconnectionStrategy): # Warn the developer warn("%s was initialized to erase credentials but you have \ specified a %s. Reconnections will fail.", self.parameters.credentials.__class__.__name__, self.reconnection.__class__.__name__) # Add our callback for if we close by being disconnected if not isinstance(self.reconnection, NullReconnectionStrategy): self.add_on_close_callback(self.reconnection.on_connection_closed) # Set all of our default connection state values self._init_connection_state() # Connect to the AMQP Broker self._connect() def _init_connection_state(self): """ Initialize or reset all of our internal state variables for a given connection. If we disconnect and reconnect, all of our state needs to be wiped """ # Outbound buffer for buffering writes until we're able to send them self.outbound_buffer = simplebuffer.SimpleBuffer() # Connection state, server properties and channels all change on # each connection self.server_properties = None self._channels = dict() # Data used for Heartbeat checking and backpressure detection self.bytes_sent = 0 self.bytes_received = 0 self.frames_sent = 0 self.heartbeat = None # Default backpressure multiplier value self._backpressure = 10 # AMQP Lifecycle States self.closed = True self.closing = False self.open = False # Our starting point once connected, first frame received self.callbacks.add(0, spec.Connection.Start, self._on_connection_start) def _adapter_connect(self, host, port): """ Subclasses should override to set up the outbound socket connection """ raise NotImplementedError('%s needs to implement this function' %\ self.__class__.__name__) def _adapter__disconnect(self): """ Subclasses should override this to cause the underlying transport (socket) to close. """ raise NotImplementedError('%s needs to implement this function' %\ self.__class__.__name__) def _connect(self): """ Call the Adapter's connect method after letting the ReconnectionStrategy know that we're going to do so. """ # Let our RS know what we're up to self.reconnection.on_connect_attempt(self) # Try and connect and send the first frame self._adapter_connect(self.parameters.host, self.parameters.port or spec.PORT) def _reconnect(self): """ Called by the Reconnection Strategy classes or Adapters to disconnect and reconnect to the broker """ # We're already closing but it may not be from reconnect, so first # Add a callback that won't be duplicated if self.closing: self.add_on_close_callback(self._reconnect) return # If we're open, we want to close normally if we can, then actually # reconnect via callback that can't be added more than once if self.open: self.add_on_close_callback(self._reconnect) self._ensure_closed() return # We're not closing and we're not open, so reconnect self._init_connection_state() self._connect() def _on_connected(self): """ This is called by our connection Adapter to let us know that we've connected and we can notify our connection strategy """ # Start the communication with the RabbitMQ Broker self._send_frame(pika.frame.ProtocolHeader()) # Let our reconnection_strategy know we're connected self.reconnection.on_transport_connected(self) def _on_connection_open(self, frame): """ This is called once we have tuned the connection with the server and called the Connection.Open on the server and it has replied with Connection.Ok. """ self.known_hosts = frame.method.known_hosts # Add a callback handler for the Broker telling us to disconnect self.callbacks.add(0, spec.Connection.Close, self._on_remote_close) # We're now connected at the AMQP level self.open = True # Call our initial callback that we're open self.callbacks.process(0, '_on_connection_open', self, self) def _on_connection_start(self, frame): """ This is called as a callback once we have received a Connection.Start from the server. """ # We're now connected to the broker self.closed = False # We didn't expect a FrameProtocolHeader, did we get one? if isinstance(frame, pika.frame.ProtocolHeader): raise ProtocolVersionMismatch(pika.frame.ProtocolHeader, frame) # Make sure that the major and minor version matches our spec version if (frame.method.version_major, frame.method.version_minor) != spec.PROTOCOL_VERSION[0:2]: raise ProtocolVersionMismatch(pika.frame.ProtocolHeader(), frame) # Get our server properties for use elsewhere self.server_properties = frame.method.server_properties # Build our StartOk authentication response from the credentials obj authentication_type, response = \ self.parameters.credentials.response_for(frame.method) # Server asked for credentials for a method we don't support so raise # an exception to let the implementing app know if not authentication_type: raise LoginError("No %s support for the credentials" %\ self.parameters.credentials.TYPE) # Erase the credentials if the credentials object wants to self.parameters.credentials.erase_credentials() # Add our callback for our Connection Tune event self.callbacks.add(0, spec.Connection.Tune, self._on_connection_tune) # Send our Connection.StartOk method = spec.Connection.StartOk(client_properties={"product": PRODUCT}, mechanism=authentication_type, response=response) self._send_method(0, method) def _combine(self, a, b): """ Pass in two values, if a is 0, return b otherwise if b is 0, return a. If neither case matches return the smallest value. """ return min(a, b) or (a or b) def _on_connection_tune(self, frame): """ Once the Broker sends back a Connection.Tune, we will set our tuning variables that have been returned to us and kick off the Heartbeat monitor if required, send our TuneOk and then the Connection. Open rpc call on channel 0 """ cmax = self._combine(self.parameters.channel_max, frame.method.channel_max) fmax = self._combine(self.parameters.frame_max, frame.method.frame_max) hint = self._combine(self.parameters.heartbeat, frame.method.heartbeat) # If we have a heartbeat interval, create a heartbeat checker if hint: self.heartbeat = HeartbeatChecker(self, hint) # Update our connection state with our tuned values self.parameters.channel_max = cmax self.parameters.frame_max = fmax # Send the TuneOk response with what we've agreed upon self._send_method(0, spec.Connection.TuneOk(channel_max=cmax, frame_max=fmax, heartbeat=hint)) # Send the Connection.Open RPC call for the vhost cmd = spec.Connection.Open(virtual_host=self.parameters.virtual_host, insist=True) self._rpc(0, cmd, self._on_connection_open, [spec.Connection.OpenOk]) def close(self, code=200, 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. """ if self.closing or self.closed: warn("%s.Close invoked while closing or closed" % \ self.__class__.__name__) return # Carry our code and text around with us self.closing = code, text # Remove the reconnection strategy callback for when we close self.callbacks.remove(0, '_on_connection_close', self.reconnection.on_connection_closed) # If we're not already closed for channel_number in self._channels.keys(): self._channels[channel_number].close(code, text) # If we already dont have any channels, close out if not self._channels: self._on_close_ready() def _on_close_ready(self): """ On a clean shutdown we'll call this once all of our channels are closed Let the Broker know we want to close """ if self.closed: warn("%s.on_close_ready invoked while closed" %\ self.__class__.__name__) return self._rpc(0, spec.Connection.Close(self.closing[0], self.closing[1], 0, 0), self._on_connection_closed, [spec.Connection.CloseOk]) def _on_connection_closed(self, frame, from_adapter=False): """ Let both our RS and Event object know we closed """ # Set that we're actually closed self.closed = True self.closing = False self.open = False # Call any callbacks registered for this self.callbacks.process(0, '_on_connection_closed', self, self) pika.log.info("Disconnected from RabbitMQ at %s:%i", self.parameters.host, self.parameters.port) # Disconnect our transport if it didn't call on_disconnected if not from_adapter: self._adapter_disconnect() def _on_remote_close(self, frame): """ We've received a remote close from the server """ self.close(frame.method.reply_code, frame.method.reply_text) def _ensure_closed(self): """ If we're not already closed, make sure we're closed """ # We carry the connection state and so we want to close if we know if self.is_open and not self.closing: self.close() @property def is_open(self): """ Returns a boolean reporting the current connection state """ return self.open and (not self.closing and not self.closed) def add_on_close_callback(self, callback): """ Add a callback notification when the connection has closed """ self.callbacks.add(0, '_on_connection_closed', callback, False) def add_on_open_callback(self, callback): """ Add a callback notification when the connection has opened """ self.callbacks.add(0, '_on_connection_open', callback, False) def add_backpressure_callback(self, callback): """ Add a callback notification when we think backpressue is being applied due to the size of the output buffer being exceeded. """ self.callbacks.add(0, 'backpressure', callback, False) def set_backpressure_multiplier(self, value=10): """ Alter the backpressure multiplier value. We set this to 10 by default. This value is used to raise warnings and trigger the backpressure callback. """ self._backpressure = value def add_timeout(self, delay_sec, callback): """ Adapters should override to call the callback after the specified number of seconds have elapsed, using a timer, or a thread, or similar. """ raise NotImplementedError('%s needs to implement this function ' %\ self.__class__.__name__) def remove_timeout(self, callback): """ Adapters should override to call the callback after the specified number of seconds have elapsed, using a timer, or a thread, or similar. """ raise NotImplementedError('%s needs to implement this function' %\ self.__class__.__name__) # Channel related functionality def channel(self, on_open_callback, 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. """ # If the user didn't specify a channel_number get the next avail if not channel_number: channel_number = self._next_channel_number() # Add the channel spec.Channel.CloseOk callback for _on_channel_close self.callbacks.add(channel_number, spec.Channel.CloseOk, self._on_channel_close) # Add it to our Channel dictionary self._channels[channel_number] = channel.Channel(self, channel_number, on_open_callback) # Add the callback for our Channel.Close event in case the Broker # wants to close us for some reason self.callbacks.add(channel_number, spec.Channel.Close, self._on_channel_close) def _next_channel_number(self): """ Return the next available channel number or raise on exception """ # Our limit is the the Codec's Channel Max or MAX_CHANNELS if it's None limit = self.parameters.channel_max or channel.MAX_CHANNELS # We've used all of our channels if len(self._channels) == limit: raise NoFreeChannels() # Get a list of all of our keys, all should be numeric channel ids channel_numbers = self._channels.keys() # We don't start with any open channels if not channel_numbers: return 1 # Our next channel is the max key value + 1 return max(channel_numbers) + 1 def _on_channel_close(self, frame): """ RPC Response from when a channel closes itself, remove from our stack """ channel_number = frame.channel_number # If we have this channel number in our channels: if channel_number in self._channels: # If our server called Channel.Close on us remotely if isinstance(frame.method, spec.Channel.Close): # Call the channel.close() function letting it know it came # From the server. self._channels[channel_number].close(frame.method.reply_code, frame.method.reply_text, True) # Forced close # Remove the channel from our dict del(self._channels[channel_number]) # If we're closing and don't have any channels, go to the next step if self.closing and not self._channels: self._on_close_ready() # Data packet and frame handling functions def _on_data_available(self, data_in): """ This is called by our Adapter, passing in the data from the socket As long as we have buffer try and map out frame data """ # Append the data self._buffer += data_in # Loop while we have a buffer and are getting frames from it while self._buffer: # Try and build a frame consumed_count, frame = pika.frame.decode_frame(self._buffer) # Remove the frame we just consumed from our data self._buffer = self._buffer[consumed_count:] # If we don't have a frame, exit if not frame: break # Increment our bytes received buffer for heartbeat checking self.bytes_received += consumed_count # If we have a Method Frame and have callbacks for it if isinstance(frame, pika.frame.Method) and \ self.callbacks.pending(frame.channel_number, frame.method): # Process the callbacks for it self.callbacks.process(frame.channel_number, # Prefix frame.method, # Key self, # Caller frame) # Args # We don't check for heartbeat frames because we can not count # atomic frames reliably due to different message behaviors # such as large content frames being transferred slowly elif isinstance(frame, pika.frame.Heartbeat): continue elif frame.channel_number > 0: # Call our Channel Handler with the frame self._channels[frame.channel_number].transport.deliver(frame) def _rpc(self, channel_number, method, callback=None, acceptable_replies=None): """ Make an RPC call for the given callback, channel number and method. acceptable_replies lists out what responses we'll process from the server with the specified callback. """ # Validate that acceptable_replies is a list or None if acceptable_replies and not isinstance(acceptable_replies, list): raise TypeError("acceptable_replies should be list or None") # Validate that the callback is a function, instancemethod or None if callback and not isinstance(callback, types.FunctionType) and \ not isinstance(callback, types.MethodType): raise TypeError("callback should be None, a function or method.") # If we were passed a callback, add it to our stack if callback: for reply in acceptable_replies: self.callbacks.add(channel_number, reply, callback) # Send the rpc call to RabbitMQ self._send_method(channel_number, method) def _send_frame(self, frame): """ This appends the fully generated frame to send to the broker to the output buffer which will be then sent via the connection adapter """ marshalled_frame = frame.marshal() self.bytes_sent += len(marshalled_frame) self.frames_sent += 1 #pika.frame.log_frame(frame.name, marshalled_frame) self.outbound_buffer.write(marshalled_frame) self._flush_outbound() avg_frame_size = self.bytes_sent / self.frames_sent if self.outbound_buffer.size > (avg_frame_size * self._backpressure): est_frames_behind = self.outbound_buffer.size / avg_frame_size message = "Pika: Write buffer exceeded warning threshold" + \ " at %i bytes and an estimated %i frames behind" warn(message % (self.outbound_buffer.size, est_frames_behind)) self.callbacks.process(0, 'backpressure', self) def _flush_outbound(self): """ Adapters should override to flush the contents of outbound_buffer out along the socket. """ raise NotImplementedError('%s needs to implement this function ' %\ self.__class__.__name__) def _send_method(self, channel_number, method, content=None): """ Constructs a RPC method frame and then sends it to the broker """ self._send_frame(pika.frame.Method(channel_number, method)) if isinstance(content, tuple): props = content[0] body = content[1] else: props = None body = content if props: length = 0 if body: length = len(body) self._send_frame(pika.frame.Header(channel_number, length, props)) if body: max_piece = (self.parameters.frame_max - \ spec.FRAME_HEADER_SIZE - \ spec.FRAME_END_SIZE) body_buf = simplebuffer.SimpleBuffer(body) while body_buf: piece_len = min(len(body_buf), max_piece) piece = body_buf.read_and_consume(piece_len) self._send_frame(pika.frame.Body(channel_number, piece)) @property def _suggested_buffer_size(self): """ Return the suggested buffer size from the connection state/tune or the default if that is None """ return self.parameters.frame_max or spec.FRAME_MAX_SIZE