python---RabbitMQ（5）消息RPC（远程过程调用）

服务器端：

import pika

#创建socket
connection = pika.BlockingConnection(pika.ConnectionParameters(
    host='localhost'))

#获取通道
channel = connection.channel()

#生成队列
channel.queue_declare(queue='rpc_queue')


def fib(n):
    '''用于获取斐波那契数列'''
    if n == 0:
        return 0
    elif n == 1:
        return 1
    else:
        return fib(n - 1) + fib(n - 2)


def on_request(ch, method, props, body):
    '''获取数据的回调函数'''
    n = int(body)

    print(" [.] fib(%s)" % n)
    response = fib(n)

    ch.basic_publish(exchange='',
                     routing_key=props.reply_to,
                     properties=pika.BasicProperties(correlation_id= 
                                                         props.correlation_id),
                     body=str(response))
    ch.basic_ack(delivery_tag=method.delivery_tag)

#设置为空闲的客户端减少压力
channel.basic_qos(prefetch_count=1)
#预备开始消费
channel.basic_consume(on_request, queue='rpc_queue')

print(" [x] Awaiting RPC requests")
#开始消费，从客户端获取
channel.start_consuming()

客户端：

import pika
import uuid


class FibonacciRpcClient(object):
    def __init__(self):
        #生成socket连接
        self.connection = pika.BlockingConnection(pika.ConnectionParameters(
            host='localhost'))
        #生成管道连接
        self.channel = self.connection.channel()
        #获取一个唯一队列名
        result = self.channel.queue_declare(exclusive=True)
        self.callback_queue = result.method.queue
        #预备消费，设置回调函数，队列名
        self.channel.basic_consume(self.on_response, no_ack=True,
                                   queue=self.callback_queue)　　
　　　　 
        #注意，在这里不使用start_consuming去获取数据，因为这样会堵塞再这里，我们使用了另一种方法self.connection.process_data_events()

    def on_response(self, ch, method, props, body):
        print("on_response")
        if self.corr_id == props.correlation_id:
            self.response = body

    def call(self, n):
        self.response = None
        #生成一个唯一标识符
        self.corr_id = str(uuid.uuid4())
        #先向服务器端发送数据，传递属性有：唯一队列名和唯一标识符
        self.channel.basic_publish(exchange='',
                                   routing_key='rpc_queue',
                                   properties=pika.BasicProperties(
                                       reply_to=self.callback_queue,
                                       correlation_id=self.corr_id,
                                   ),
                                   body=str(n))

        while self.response is None:
            print("process_data_events start")
            self.connection.process_data_events()
            print("process_data_events end")
        return int(self.response)


fibonacci_rpc = FibonacciRpcClient()

print(" [x] Requesting fib(30)")
response = fibonacci_rpc.call(30)
print(" [.] Got %r" % response)

注意：

self.connection.process_data_events()会去队列中获取处理数据事件，当数据来临的时候，会直接去调用回调函数去处理数据

process_data_events start
process_data_events end
process_data_events start
process_data_events end
process_data_events start
process_data_events end
process_data_events start
process_data_events end
process_data_events start
process_data_events end
process_data_events start
process_data_events end
process_data_events start
process_data_events end
process_data_events start
process_data_events end
process_data_events start
process_data_events end
process_data_events start
process_data_events end
process_data_events start
process_data_events end
process_data_events start　　#事件到来
on_response　　#调用回调函数去处理数据
process_data_events end　　#事件结束
 [.] Got 832040