zeroMQ初体验-6.多模式数据来源处理方案(multi sockets)

asia 2011-03-24

之前已经讲过,zeroMQ是可以多对多的,但需要成对匹配才行,即多个发布端都是同一种模式,而这里要涉及到的是,多个发布端模式不统一的情况。

文中先给出了一个比较"脏"的处理方式:

import zmq
import time

context = zmq.Context()

receiver = context.socket(zmq.PULL)
receiver.connect("tcp://localhost:5557")

subscriber = context.socket(zmq.SUB)
subscriber.connect("tcp://localhost:5556")
subscriber.setsockopt(zmq.SUBSCRIBE, "10001")

while True:

    while True:
        try:
            rc = receiver.recv(zmq.NOBLOCK)#这是非阻塞模式
        except zmq.ZMQError:
            break

    while True:
        try:
            rc = subscriber.recv(zmq.NOBLOCK)
        except zmq.ZMQError:
            break

显然,如此做既不优雅,还有出现单来源循环不止,另一来源又得不到响应的状况。

自然,官方也做了相应的封装,给了一个相对优雅的实现:

import zmq

context = zmq.Context()

receiver = context.socket(zmq.PULL)
receiver.connect("tcp://localhost:5557")

subscriber = context.socket(zmq.SUB)
subscriber.connect("tcp://localhost:5556")
subscriber.setsockopt(zmq.SUBSCRIBE, "10001")

poller = zmq.Poller()
poller.register(receiver, zmq.POLLIN)
poller.register(subscriber, zmq.POLLIN)

while True:
    socks = dict(poller.poll())

    if receiver in socks and socks[receiver] == zmq.POLLIN:
        message = receiver.recv()

    if subscriber in socks and socks[subscriber] == zmq.POLLIN:
        message = subscriber.recv()

这种方式采用了平衡兼顾的原则,实现了类似于同一模式多发布端推送的"平衡队列"功能。

(未完待续)

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