9 from vstf.common import message
10 from vstf.rpc_frame_work import constant
12 LOGGER = logging.getLogger(__name__)
15 class VstfConsumer(object):
16 """This is an example consumer that will handle unexpected interactions
17 with RabbitMQ such as channel and connection closures.
19 If RabbitMQ closes the connection, it will reopen it. You should
20 look at the output, as there are limited reasons why the connection may
21 be closed, which usually are tied to permission related issues or
24 If the channel is closed, it will indicate a problem with one of the
25 commands that were issued and that should surface in the output as well.
29 def __init__(self, agent,
35 """Create a new instance of the consumer class, passing in the AMQP
36 URL used to connect to RabbitMQ.
38 :param str user: The user name of RabbitMQ server
39 :param str passwd: The passwd of RabbitMQ server
40 :param str host: The ip of RabbitMQ server
41 :param str port: connection's port
44 self._connection = None
47 self._consumer_tag = None
52 self.agent_id = agent_id
53 self.url = 'amqp://' + self.user + ':' + self.passwd + '@' + self.srv + ':' + self.port + '/%2F'
55 # load the agent_funcs
57 self.agent_ops = stevedore.driver.DriverManager(
58 namespace="agent.plugins",
61 except Exception as e:
62 LOGGER.error(message.dumpstrace())
65 super(VstfConsumer, self).__init__()
68 """This method connects to RabbitMQ, returning the connection handle.
69 When the connection is established, the on_connection_open method
70 will be invoked by pika.
72 :rtype: pika.SelectConnection
75 LOGGER.info('Connecting to %s:%s', self.srv, self.port)
76 return pika.SelectConnection(pika.URLParameters(self.url),
77 self.on_connection_open,
78 stop_ioloop_on_close=False)
80 # return pika.SelectConnection(pika.ConnectionParameters(host="%s:%s" %(self.srv,self.port)),
81 # self.on_connection_open,
82 # stop_ioloop_on_close=False)
84 def on_connection_open(self, unused_connection):
85 """This method is called by pika once the connection to RabbitMQ has
86 been established. It passes the handle to the connection object in
87 case we need it, but in this case, we'll just mark it unused.
89 :type unused_connection: pika.SelectConnection
92 LOGGER.info('Connection opened')
93 self.add_on_connection_close_callback()
96 def add_on_connection_close_callback(self):
97 """This method adds an on close callback that will be invoked by pika
98 when RabbitMQ closes the connection to the publisher unexpectedly.
101 LOGGER.info('Adding connection close callback')
102 self._connection.add_on_close_callback(self.on_connection_closed)
104 def on_connection_closed(self, connection, reply_code, reply_text):
105 """This method is invoked by pika when the connection to RabbitMQ is
106 closed unexpectedly. Since it is unexpected, we will reconnect to
107 RabbitMQ if it disconnects.
109 :param pika.connection.Connection connection: The closed connection obj
110 :param int reply_code: The server provided reply_code if given
111 :param str reply_text: The server provided reply_text if given
116 self._connection.ioloop.stop()
118 LOGGER.warning('Connection closed, reopening in 2 seconds: (%s) %s',
119 reply_code, reply_text)
120 self._connection.add_timeout(2, self.reconnect)
123 """Will be invoked by the IOLoop timer if the connection is
124 closed. See the on_connection_closed method.
127 # This is the old connection IOLoop instance, stop its ioloop
128 # Sometimes the broken connection may be exception
130 self._connection.ioloop.stop()
134 while not self._closing:
135 # Create a new connection
137 self._connection = self.connect()
139 LOGGER.error(message.dumpstrace())
144 # There is now a new connection, needs a new ioloop to run
145 self._connection.ioloop.start()
147 def open_channel(self):
148 """Open a new channel with RabbitMQ by issuing the Channel.Open RPC
149 command. When RabbitMQ responds that the channel is open, the
150 on_channel_open callback will be invoked by pika.
153 LOGGER.info('Creating a new channel')
154 self._connection.channel(on_open_callback=self.on_channel_open)
156 def on_channel_open(self, channel):
157 """This method is invoked by pika when the channel has been opened.
158 The channel object is passed in so we can make use of it.
160 Since the channel is now open, we'll declare the exchange to use.
162 :param pika.channel.Channel channel: The channel object
165 LOGGER.info('Channel opened')
166 self._channel = channel
167 self.add_on_channel_close_callback()
168 self.setup_exchanges()
170 def add_on_channel_close_callback(self):
171 """This method tells pika to call the on_channel_closed method if
172 RabbitMQ unexpectedly closes the channel.
175 LOGGER.info('Adding channel close callback')
176 self._channel.add_on_close_callback(self.on_channel_closed)
178 def on_channel_closed(self, channel, reply_code, reply_text):
179 """Invoked by pika when RabbitMQ unexpectedly closes the channel.
180 Channels are usually closed if you attempt to do something that
181 violates the protocol, such as re-declare an exchange or queue with
182 different parameters. In this case, we'll close the connection
183 to shutdown the object.
185 :param pika.channel.Channel: The closed channel
186 :param int reply_code: The numeric reason the channel was closed
187 :param str reply_text: The text reason the channel was closed
190 LOGGER.warning('Channel %i was closed: (%s) %s',
191 channel, reply_code, reply_text)
192 self._connection.close()
194 def setup_exchanges(self):
195 """Setup the exchange on RabbitMQ by invoking the Exchange.Declare RPC
196 command. When it is complete, the on_exchange_declareok method will
199 :param str|unicode exchange_name: The name of the exchange to declare
202 LOGGER.info('Declaring %s exchange %s', constant.DIRECT, constant.exchange_d)
203 self._channel.exchange_declare(self.on_direct_exchange_declareok,
207 # LOGGER.info('Declaring %s exchange %s', constant.FAN, constant.fan_exchange)
208 # self._channel.exchange_declare(self.on_fan_exchange_declareok,
209 # constant.fan_exchange,
212 def on_fan_exchange_declareok(self, unused_frame):
213 """Invoked by pika when RabbitMQ has finished the Exchange.Declare RPC
216 :param pika.Frame.Method unused_frame: Exchange.DeclareOk response frame
219 LOGGER.info('Exchange declared')
222 def on_direct_exchange_declareok(self, unused_frame):
223 queue_name = constant.queue_common + self.agent_id
224 self.setup_queue(queue_name, self.on_direct_queue_declareok)
226 def setup_queue(self, queue_name, next_ops):
227 """Setup the queue on RabbitMQ by invoking the Queue.Declare RPC
228 command. When it is complete, the on_queue_declareok method will
231 :param str|unicode queue_name: The name of the queue to declare.
234 LOGGER.info('Declaring queue %s', queue_name)
235 self._channel.queue_declare(next_ops,
239 def on_direct_queue_declareok(self, method_frame):
240 """Method invoked by pika when the Queue.Declare RPC call made in
241 setup_queue has completed. In this method we will bind the queue
242 and exchange together with the routing key by issuing the Queue.Bind
243 RPC command. When this command is complete, the on_bindok method will
246 :param pika.frame.Method method_frame: The Queue.DeclareOk frame
249 queue_name = constant.queue_common + self.agent_id
250 LOGGER.info('Binding %s to %s with %s',
251 queue_name, constant.exchange_d, queue_name)
252 self._channel.queue_bind(self.on_bindok, queue_name,
253 constant.exchange_d, queue_name)
255 def on_bindok(self, unused_frame):
256 """Invoked by pika when the Queue.Bind method has completed. At this
257 point we will start consuming messages by calling start_consuming
258 which will invoke the needed RPC commands to start the process.
260 :param pika.frame.Method unused_frame: The Queue.BindOk response frame
263 LOGGER.info('Queue bound')
264 self.start_consuming()
266 def start_consuming(self):
267 """This method sets up the consumer by first calling
268 add_on_cancel_callback so that the object is notified if RabbitMQ
269 cancels the consumer. It then issues the Basic.Consume RPC command
270 which returns the consumer tag that is used to uniquely identify the
271 consumer with RabbitMQ. We keep the value to use it when we want to
272 cancel consuming. The on_message method is passed in as a callback pika
273 will invoke when a message is fully received.
276 queue_name = constant.queue_common + self.agent_id
277 LOGGER.info('Issuing consumer related RPC commands')
278 self.add_on_cancel_callback()
279 self._consumer_tag = self._channel.basic_consume(self.on_message,
282 def add_on_cancel_callback(self):
283 """Add a callback that will be invoked if RabbitMQ cancels the consumer
284 for some reason. If RabbitMQ does cancel the consumer,
285 on_consumer_cancelled will be invoked by pika.
288 LOGGER.info('Adding consumer cancellation callback')
289 self._channel.add_on_cancel_callback(self.on_consumer_cancelled)
291 def on_consumer_cancelled(self, method_frame):
292 """Invoked by pika when RabbitMQ sends a Basic.Cancel for a consumer
295 :param pika.frame.Method method_frame: The Basic.Cancel frame
298 LOGGER.info('Consumer was cancelled remotely, shutting down: %r',
301 self._channel.close()
303 def on_message(self, respone_chanl, basic_deliver, properties, body):
304 """Invoked by pika when a message is delivered from RabbitMQ. The
305 channel is passed for your convenience. The basic_deliver object that
306 is passed in carries the exchange, routing key, delivery tag and
307 a redelivered flag for the message. The properties passed in is an
308 instance of BasicProperties with the message properties and the body
309 is the message that was sent.
311 :param pika.channel.Channel unused_channel: The channel object
312 :param pika.Spec.Basic.Deliver: basic_deliver method
313 :param pika.Spec.BasicProperties: properties
314 :param str|unicode body: The message body
317 LOGGER.info('Received message # %s from %s: %s',
318 basic_deliver.delivery_tag, properties.app_id, body)
320 msg = message.decode(body)
321 head = message.get_context(msg)
322 main_body = message.get_body(msg)
324 LOGGER.debug("recive the msg: head:%(h)s, body:%(b)s",
328 func = getattr(self.agent_ops.driver, main_body.get('method'))
329 response = func(**main_body.get('args'))
330 except Exception as e:
331 LOGGER.error(message.dumpstrace())
332 LOGGER.error("request happend error")
333 response = {'exception': {'name': e.__class__.__name__,
334 'message': e.message,
337 response = message.add_context(response, **head)
338 LOGGER.debug("response the msg: head:%(h)s, body:%(b)s",
339 {'h': response.get('head'), 'b': response.get('body')})
341 respone_chanl.basic_publish(exchange=constant.exchange_d,
342 routing_key=properties.reply_to,
343 properties=pika.BasicProperties(correlation_id=properties.correlation_id),
344 body=message.encode(response)
346 # no matter what happend, tell the mq-server to drop this msg.
348 self.acknowledge_message(basic_deliver.delivery_tag)
350 def acknowledge_message(self, delivery_tag):
351 """Acknowledge the message delivery from RabbitMQ by sending a
352 Basic.Ack RPC method for the delivery tag.
354 :param int delivery_tag: The delivery tag from the Basic.Deliver frame
357 LOGGER.info('Acknowledging message %s', delivery_tag)
358 self._channel.basic_ack(delivery_tag)
360 def stop_consuming(self):
361 """Tell RabbitMQ that you would like to stop consuming by sending the
362 Basic.Cancel RPC command.
366 LOGGER.info('Sending a Basic.Cancel RPC command to RabbitMQ')
367 self._channel.basic_cancel(self.on_cancelok, self._consumer_tag)
369 def on_cancelok(self, unused_frame):
370 """This method is invoked by pika when RabbitMQ acknowledges the
371 cancellation of a consumer. At this point we will close the channel.
372 This will invoke the on_channel_closed method once the channel has been
373 closed, which will in-turn close the connection.
375 :param pika.frame.Method unused_frame: The Basic.CancelOk frame
378 LOGGER.info('RabbitMQ acknowledged the cancellation of the consumer')
381 def close_channel(self):
382 """Call to close the channel with RabbitMQ cleanly by issuing the
383 Channel.Close RPC command.
386 LOGGER.info('Closing the channel')
387 self._channel.close()
390 """Run the example consumer by connecting to RabbitMQ and then
391 starting the IOLoop to block and allow the SelectConnection to operate.
395 self._connection = self.connect()
396 except Exception as e:
397 LOGGER.error(message.dumpstrace())
398 self._connection.ioloop.start()
401 """Cleanly shutdown the connection to RabbitMQ by stopping the consumer
402 with RabbitMQ. When RabbitMQ confirms the cancellation, on_cancelok
403 will be invoked by pika, which will then closing the channel and
404 connection. The IOLoop is started again because this method is invoked
405 when CTRL-C is pressed raising a KeyboardInterrupt exception. This
406 exception stops the IOLoop which needs to be running for pika to
407 communicate with RabbitMQ. All of the commands issued prior to starting
408 the IOLoop will be buffered but not processed.
411 LOGGER.info('Stopping')
413 self.stop_consuming()
414 self._connection.ioloop.stop()
415 self.close_connection()
416 LOGGER.info('Stopped')
418 def close_connection(self):
419 """This method closes the connection to RabbitMQ."""
420 LOGGER.info('Closing connection')
421 self._connection.close()